Journal articles: 'Drug-reduced regimens' – Grafiati (2024)

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ABSTRACTUnderstanding the relationship between antibiotic exposure and amplification of bacterial subpopulations with reduced drug susceptibility over time is important for evaluating the adequacy of dosing regimens. We utilized a hollow-fiber infection model to identify the fosfomycin intravenous dosing regimens that prevented the amplification ofEscherichia colibacterial subpopulations with reduced fosfomycin susceptibility. The challenge isolate wasE. coliATCC 25922 (agar MIC with glucose-6-phosphate, 1 mg/liter; agar MIC without glucose-6-phosphate, 32 mg/liter). The fosfomycin dosing regimens studied were 1 to 12 g every 8 h for 10 days to approximate that planned for clinical use. The studies included a no-treatment control regimen. Two bacterial subpopulations were identified, one with reduced susceptibility with agar MIC values ranging from 32 to 128 mg/liter and the other resistant with agar MIC values of 256 to >1,024 mg/liter on plates containing 5× and 256× the baseline MIC value, respectively. An inverted-U-shaped function best described the relationship between the amplification of the two bacterial subpopulations and drug exposure. The lowest fosfomycin dosing regimen that did not amplify a bacterial subpopulation with reduced susceptibility was 4 g administered every 8 h. Nearly immediate amplification of bacterial subpopulations with reduced susceptibility was observed with fosfomycin dosing regimens consisting of 1 to 2 g every 8 h. These data will be useful to support the selection of fosfomycin dosing regimens that minimize the potential for on-therapy amplification of bacterial subpopulations with reduced susceptibility.

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Purpose To identify the cost and reasons of returned parenteral chemotherapy regimens at a tertiary hospital in Kuala Lumpur, Malaysia. Methods Data were retrospectively extracted from all the Chemotherapy Return Forms in 2016, which is a compulsory documentation accompanying each return of parenteral chemotherapy regimen. The following data were extracted: patient’s diagnosis, gender, location of treatment (i.e. ward/daycare clinic), start date of chemotherapy regimen, type of cytotoxic drug returned, dose of cytotoxic drug returned, number of cytotoxic drug preparations returned and reason for return as well as whether the returned cytotoxic drug preparations could be re-dispensed. The cost of wastage was calculated based on the cost per mg (or per unit) of the particular returned cytotoxic drug. Results One hundred and fifty-nine cases of returned chemotherapy regimen comprising of 231 parenteral cytotoxic drug preparations were analysed. The total cost of returned chemotherapy regimen for 2016 was €3632, with €756 (20.8%) worth of chemotherapy regimens returned due to preventable reasons and €2876 (79.2%) worth of chemotherapy regimens returned due to non-preventable reasons. Approximately 50% of cases returned chemotherapy regimen were due to deterioration of patient’s clinical condition and another 24.5% of cases of returned chemotherapy regimen were attributed to adverse drug reactions. Conclusion Wastage associated to non-preventable reasons such as adverse drug reactions and preventable causes like refusal of patients can be further reduced by using newer healthcare innovations and establishment of written institutional protocols or standard operating procedures as references for in-charge healthcare personnel when cytotoxic drug-related issues occur. Adoption of cost-saving strategies that have been proven by studies could further improve current cost containment strategies.

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ABSTRACTShortening the lengthy treatment duration for tuberculosis patients is a major goal of current drug development efforts. The common marmoset develops human-like disease pathology and offers an attractive model to better understand the basis for relapse and test regimens for effective shorter duration therapy. We treatedMycobacterium tuberculosis-infected marmosets with two drug regimens known to differ in their relapse rates in human clinical trials: the standard four-drug combination of isoniazid, rifampin, pyrazinamide, and ethambutol (HRZE) that has very low relapse rates and the combination of isoniazid and streptomycin that is associated with higher relapse rates. As early as 2 weeks, the more sterilizing regimen significantly reduced the volume of lung disease by computed tomography (P= 0.035) and also significantly reduced uptake of [18F]-2-fluoro-2-deoxyglucose by positron emission tomography (P= 0.049). After 6 weeks of therapy, both treatments caused similar reductions in granuloma bacterial load, but the more sterilizing, four-drug regimen caused greater reduction in bacterial load in cavitary lesions (P= 0.009). These findings, combined with the association in humans between cavitary disease and relapse, suggest that the basis for improved sterilizing activity of the four-drug combination is both its faster disease volume resolution and its stronger sterilizing effect on cavitary lesions. Definitive data from relapse experiments are needed to support this observation.

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Abstract Background Characterizing the mutations selected by the integrase strand transfer inhibitor (INSTI) dolutegravir and their effects on susceptibility is essential for identifying viruses less likely to respond to dolutegravir therapy and for monitoring persons with virological failure (VF) on dolutegravir therapy. Methods We systematically reviewed dolutegravir resistance studies to identify mutations emerging under dolutegravir selection pressure, the effect of INSTI resistance mutations on in vitro dolutegravir susceptibility, and the virological efficacy of dolutegravir in antiretroviral-experienced persons. Results and conclusions We analysed 14 studies describing 84 in vitro passage experiments, 26 studies describing 63 persons developing VF plus INSTI resistance mutations on a dolutegravir-containing regimen, 41 studies describing dolutegravir susceptibility results, and 22 clinical trials and 16 cohort studies of dolutegravir-containing regimens. The most common INSTI resistance mutations in persons with VF on a dolutegravir-containing regimen were R263K, G118R, N155H and Q148H/R, with R263K and G118R predominating in previously INSTI-naive persons. R263K reduced dolutegravir susceptibility ∼2-fold. G118R generally reduced dolutegravir susceptibility >5-fold. The highest levels of reduced susceptibility occurred in viruses containing Q148 mutations in combination with G140 and/or E138 mutations. Dolutegravir two-drug regimens were highly effective for first-line therapy and for virologically suppressed persons provided dolutegravir’s companion drug was fully active. Dolutegravir three-drug regimens were highly effective for salvage therapy in INSTI-naive persons provided one or more of dolutegravir’s companion drugs was fully active. However, dolutegravir monotherapy in virologically suppressed persons and functional dolutegravir monotherapy in persons with active viral replication were associated with a non-trivial risk of VF plus INSTI resistance mutations.

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ABSTRACTNew regimens based on two or more novel agents are sought to shorten or simplify treatment of tuberculosis (TB). Pretomanid (PMD) is a nitroimidazole in phase 3 trials that has significant bactericidal activity alone and in combination with bedaquiline (BDQ) and/or pyrazinamide (PZA). We previously showed that the novel combination of BDQ+PMD plus the oxazolidinone sutezolid (SZD) had sterilizing activity superior to that of the first-line regimen in a murine model of TB. The present experiments compared the activity of different oxazolidinones in combination with BDQ+PMD with or without PZA in the same model. The 3-drug regimen of BDQ+PMD plus linezolid (LZD) had sterilizing activity approaching that of BDQ+PMD+SZD and superior to that of the first-line regimen. The addition of PZA further enhanced activity. Reducing the duration of LZD to 1 month did not significantly affect the activity of the regimen. Halving the LZD dose or replacing LZD with RWJ-416457 modestly reduced activity over the first month but not after 2 months. AZD5847 and tedizolid also increased the bactericidal activity of BDQ+PMD, but they were less effective than the other oxazolidinones. These results provide optimism for safe, short-course oral regimens for drug-resistant TB that may also be superior to the current first-line regimen for drug-susceptible TB.

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ABSTRACTStudies were conducted to determine if there is a mechanistic basis for reports of suboptimal virologic responses and concerns regarding the safety of regimens containing the combination of tenofovir (TFV) disoproxil fumarate (TDF) and didanosine (ddI) by assessing the pharmaco*kinetic consequences of coadministration of these drugs on intracellular nucleotides. This was a prospective and longitudinal study in HIV-1-infected patients of adding either TDF or ddI to a stable antiretroviral regimen containing the other drug. Intracellular concentrations of the nucleotide analogs TFV diphosphate (TFV-DP) and ddATP and the endogenous purine nucleotides dATP and 2′-dGTP in peripheral blood mononuclear cells were measured. A total of 16 patients were enrolled into the two study arms and a study extension. Intracellular TFV-DP concentrations (median, 120 fmol/106cells) and ddATP concentrations (range, 1.50 to 7.54 fmol/106cells in two patients) were unaffected following addition of ddI or TDF to a stable regimen containing the other drug. While coadministration of ddI and TDF for 4 weeks did not appear to impact dATP or dGTP concentrations, cross-sectional analysis suggested that extended therapy with ddI-containing regimens, irrespective of TDF coadministration, may decrease dATP and ddATP concentrations. Addition of TDF or ddI to a stable regimen including the other drug, in the context of ddI dose reduction, did not adversely affect the concentration of dATP, dGTP, TFV-DP, or ddATP. The association between longer-term ddI therapy and reduced intracellular nucleotide concentrations and this observation's implication for the efficacy and toxicity of ddI-containing regimens deserve further study.

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Aim. To evaluate the clinical efficacy and safety of antiviral drug riamilovir in patients with acute respiratory viral infections (ARVI) of non-coronavirus (SARS-CoV-2) etiology with different dosing regimens. Materials and methods. The study included 150 patients with ARVI aged 18–27 years (50 patients received riamilovir in the regimen of 250 mg 3 times a day for 5 days, 50 patients received riamilovir in the off label regimen of 250 mg 5 times a day for 5 days, 50 patients received only pathogenetic treatment). Results. The use of riamilovir in both treatment regimens led to a reduction in the duration of inpatient treatment. The shortest periods of hospitalization were noted in patients who received the study drug at higher daily dosages. The use of riamilovir reduced the duration and severity of general infectious manifestations of the disease, while the shortest total duration of fever and a number of respiratory tract syndromes was registered among people who received riamilovir in the regimen of 1250 mg per day for 5 days, no adverse events were registered, additionally, 100% elimination of ARVI pathogens was noted in 1250 mg per day group. Conclusion. Riamilovir has shown clinical efficacy and a good safety profile in in both treatment regimens. The dosage regimen of 1250 mg per day led to more significant clinical effects and to 100% elimination of ARVI pathogens in the study group by the 6th day of hospitalization.

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ABSTRACTThe repurposing of existing drugs is being pursued as a means by which to accelerate the development of novel regimens for the treatment of drug-susceptible and drug-resistant tuberculosis (TB). In the current study, we assessed the activity of the antipsychotic drug thioridazine (TRZ) in combination with the standard regimen in a well-validated murine TB model. Single-dose and steady-state pharmaco*kinetic studies were performed in BALB/c mice to establish human-equivalent doses of TRZ. To determine the bactericidal activity of TRZ against TB in BALB/c mice, three separate studies were performed, including a dose-ranging study of TRZ monotherapy and efficacy studies of human-equivalent doses of TRZ with and without isoniazid (INH) or rifampin (RIF). Therapeutic efficacy was assessed by the change in mycobacterial load in the lung. The human-equivalent dose of thioridazine was determined to be 25 mg/kg of body weight, which was well tolerated in mice. TRZ was found to accumulate at high concentrations in lung tissue relative to serum levels. We observed modest synergy during coadministration of TRZ with INH, and the addition of TRZ reduced the emergence of INH-resistant mutants in mouse lungs. In conclusion, this study further illustrates the opportunity to reevaluate the contribution of TRZ to the sterilizing activity of combination regimens to prevent the emergence of drug-resistantM. tuberculosis.

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A brief therapeutic regimen of praziquantel, reduced to a single day, has been effective for treatment of neurocysticercosis. To study its pharmaco*kinetic characteristics, levels of praziquantel in plasma were determined for eight healthy volunteers after the administration of three oral doses of 25 mg/kg of body weight given at 2-h intervals, alone and with the simultaneous administration of cimetidine. Each volunteer received both regimens in a randomized crossover design. Blood samples were taken during a period of 12 h, and praziquantel concentration was measured by high-performance liquid chromatography. Levels of praziquantel in plasma remained above 300 ng/ml during a period of 12 h; they increased 100% when cimetidine was jointly administered. Compared with other regimens, the high levels obtained and the longer duration of action seem to be advantageous in prolonging the exposure of the parasites to the drug and support previous clinical experience showing that the treatment of neurocysticercosis with praziquantel can be reduced from 2 weeks to 1 day with the drug still retaining its cysticidal properties. Moreover, simultaneous administration of praziquantel and cimetidine could improve further the efficacy of the single-day therapy for cysticercosis and other parasitic diseases, such as schistosomiasis.

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Fragility scales are intended to help in therapeutic decisions. Here, we asked if the fragility assessment in MM patients ≥ 75 years old qualified for treatment by the local physician correlates with the choice of treatment: a two- or three-drug regimens. Between 7/2018 and 12/2019, we prospectively enrolled 197 MM patients at the start of treatment from the 13 Polish Myeloma Group centers. The data to assess fragility were prospectively collected, but centrally assessed fragility was not disclosed to the local center. The activity of daily living (ADL) could be assessed in 192 (97.5%) and was independent in 158 (80.2%), moderately impaired in 23 (11.7%), and 11 (5.6%) in completely dependent. Patients with more than three comorbidities made up 26.9% (53 patients). Thus, according to the Palumbo calculator, 43 patients were in the intermediate fitness group (21.8%), and the rest belonged to the frailty group (153, 77.7%). Overall, 79.7% of patients (157) received three-drug regimens and 20.3% (40) received two-drug regimens. In each ECOG group, more than three out of four patients received three-drug regimens. According to the ADL scale, 82.3% of the independent 65.2% of moderately impaired, and 81.8% of the dependent received three-drug regimens. Out of 53 patients with at least four comorbidities, 71.7% received three-drug regimens, and the rest received two-drug regimens. Thirty-four patients from the intermediate fit group (79.0%), and 123 (79.9%) from the frail group received three-drug regimens. Early mortality occurred in 25 patients (12.7%). No one discontinued treatment due to toxicity. To conclude, MM patients over 75 are mainly treated with triple-drug regimens, not only in reduced doses, regardless of their frailty scores. However, the absence of prospective fragility assessment did not negatively affect early mortality and the number of treatment discontinuations, which brings into question the clinical utility of current fragility scales in everyday practice.

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Abstract Abstract 1840 Background: We have recently identified clonogenic malignant stem cell populations in human mantle cell lymphoma (MCL), is a particularly deadly subtype of Non-Hodgkin's Lymphoma (NHL). We have discovered that CD45+CD19-MCL cells, which we termed MCL-initiating cells (MCL-ICs), are highly tumorigenic and display self-renewal capacities in vivo; in contrast, CD45+CD19+ MCL cells, which constitute the vast majority of cells within the tumors, show no self-renewal capacities and display greatly reduced tumorigenicity. Given the newly appreciated roles of cancer stem cells in the drug resistance of some cancers, it is critical to investigate whether MCL-ICs play roles in drug resistance of human MCL. Methods: CD45+CD19- and CD45+CD19+ cells isolated from MCL patients was tested for functional roles of MCL-ICs in drug-resistance of MCL using clinically-relevant chemotherapeutic regimens: R-CHOP, R-hyperCVAD, R-DHAP, R-HAD+B, and fludarabine-based regimen. We compared the cytotoxic effects and IC50 values of above regimens between two cell groups. To understand molecular mechanisms of drug resistance of MCL-ICs, we examined the cell cycle status of MCL-ICs using Rhodamine 123. Results: Cytotoxicity assay showed that MCL-ICs are more resistant to clinically relevant combined chemotherapeutic regimens in vitro as compared to bulk MCL tumor cells. Annexin V apoptosis assay supported this finding. IC50 values of chemotherapeutic agents that can induce the effective cytotoxicity of CD45+CD19-MCL-ICs were significantly higher than those of CD45+CD19+ MCL cells in most regimens. In contrast with CD45+CD19+ MCL cells, no significant growth inhibition was noted in CD45+CD19-MCL-ICs with combined drug treatments as well as a single agent. Rhodamine 123 efflux activity tests showed that MCL-ICs are maintained in a quiescent status. Conclusions: We have discovered MCL-ICs were more resistant to various clinically relevant chemotherapeutic agents in combination or in a single regimen compared to CD45+CD19+ MCL cells. The resistance of MCL-ICs to drugs was largely due to quiescent properties with enriched ABC drug transporters. In conclusion, designing novel therapies that can kill MCL-ICs may prevent relapse and increase patient survival. Disclosures: No relevant conflicts of interest to declare.

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ABSTRACTExtensively drug-resistant (XDR)Acinetobacterspp. have emerged as a cause of nosocomial infections, especially under conditions of intensive care. Unfortunately, resistance to colistin is increasing and there is a need for new therapeutic options. We aimed to study the effect of some novel combinations against XDRAcinetobacter baumanniiin anin vitropharmaco*kinetics-pharmacodynamics (PK/PD) model. Three nonrelated clinical strains of XDRA. baumanniiwere investigated. Antibiotic-simulated regimens were colistin at 3 MU every 8 h (q8h) (first dose, 6 MU), daptomycin at 10 mg/kg of body weight q24h, imipenem at 1 g q8h, and ertapenem at 1 g q24h. Combination regimens included colistin plus daptomycin, colistin plus imipenem, and imipenem plus ertapenem. Samples were obtained at 0, 1, 2, 4, 8, and 24 h. Among the single-agent regimens, only the colistin regimen resulted in significant reductions in log10CFU per milliliter compared to the control for all the strains tested. Although colistin achieved bactericidal activity at 4 h, it was not able to reach the limit of detection (1 log10CFU/ml). One strain had significant regrowth at 24 h without the emergence of resistance. Daptomycin-colistin combinations led to a significant reduction in levels of log10CFU per milliliter that were better than those achieved with colistin as a single-agent regimen, reaching the limit of detection at 24 h against all the strains. The combination of imipenem plus ertapenem outperformed the colistin regimen, although the results did not reach the limit of detection, with significant regrowth at 24 h. Similarly, colistin-plus-imipenem combinations reduced the levels of log10CFU per milliliter at 8 h, with significant regrowth at 24 h but with development of resistance to colistin. We have shown some potentially useful alternatives for the treatment of extensively drug-resistantA. baumannii. Among them, the daptomycin-colistin combination was the most effective and should be investigated in future studies.

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4564 Background: Pazopanib has been licensed for advanced soft tissue sarcoma and metastatic renal cell carcinoma in a fixed oral daily dose of 800mg taken fasted. We hypothesized that ingesting pazopanib with food may improve patients’ comfort and reduce gastro-intestinal adverse events. Moreover, a food intervention, resulting in a better absorption, can lead to a lower dose, which could significantly reduce treatment costs. Methods: Part 1 of the study was performed to determine whether 600mg pazopanib taken with a continental breakfast was bioequivalent to 800mg pazopanib taken fasted. In part 2, differences in GI-toxicity and patient satisfaction were assessed by the cancer-therapy-satisfaction-questionnaire after both intake regimens. Finally, patient’s preference for either intake regimen was asked. Results: 16 patients were included in the bioequivalence study. The geometric mean ratio (fed/fasted) of the area under the plasma concentration time curve was 1.10 (90% CI 1.00-1.19), maximum peak concentration was 1.12 (90% CI 1.02-1.22) and pazopanib trough concentration was 1.10 (90% CI 1.02-1.18). In part 2, 60 patients were included. No differences were seen in the occurrence of GI-toxicities under both intake regimens. Patients seem to be more positive about their feelings about side effects (72.3(95% CI 68.1-76.5) vs 68·2 (62.7-73.6); p=.092) and satisfaction with therapy scores were higher (84.7(95% CI 81.4-87.9) vs 81.9 (78.7-85.2); p= .059) when pazopanib was taken with food. 41 (68%) of the patients preferred the intake with continental breakfast. Conclusions: Intake of 600mg pazopanib with food results in bioequivalent exposure and was preferred over a standard pazopanib dose without food. Moreover, with this simple food intervention a large cost reduction can be realized in patients treated with pazopanib. Clinical trial information: NCT02138526.

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Abstract The identification of JAK-STAT pathway mutations in the majority of patients with the myeloproliferative neoplasms (MPN) polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF) led the to clinical development of JAK inhibitors, and the resultant approval of ruxolitinib for the treatment of PMF. However, despite this important therapeutic advance, there are significant limitations to JAK inhibitor therapy both with respect to efficacy and toxicity. First, although JAK inhibitors reduce splenomegaly, ameliorate symptoms, and improve long-term outcome, they do not achieve molecular or pathologic remission at currently utilized dosing strategies. Second, JAK2 has a role in hematopoiesis and other biological processes, and JAK inhibition leads to significant hematologic toxicities including anemia and thrombocytopenia. We recently used genetic and pharmacologic studies to demonstrate that JAK inhibitor persistent cells which survive JAK inhibitor therapy in vitro and in vivo remain JAK2 dependent, consistent with incomplete target inhibition. As such, we hypothesized that alternate dosing regimens which allow for intermittent, maximal target inhibition might increase efficacy and reduce toxicity. We therefore used experimental and modeling approaches to investigate the potential efficacy of alternate dosing regimens. We first explored the effects of chronic vs intermittent dosing in vitro by altering the treatment regimen in cell lines. To this end, we treated the JAK2 V617F mutant cell line, SET-2, and JAK2-wild-type (control) cell lines with ruxolitinib (1µM vs 0.5 µM) on a chronic or intermittent (alternating 1 week on and 1 week off the drug) basis. We then performed cell viability assays using flow cytometry to estimate the effect of the drug on the cell division and death rates of each cell population. Using this data, we developed a mathematical model to predict responses to varying dose therapy. Cell proliferation was described using an exponential growth model (pt2 = pt1 e(birth rate-death rate)Dt, p=population size). Birth and death rates as a function of the drug concentration was fitted using a simple iterative least squares estimation from the in vitro collected data, where death(c) = 0.0046log(1.5014 + 30.4910c) and birth(c) = 0.0098 + 0.0051e-1.2946c. Treatment cycles were modeled by ton + toff for pulsitile versus chronic (toff = 0) regimens for time on and off drug. We also added a toxicity constraint based on preclinical testing and the mathematical model T(c) = (α/c) –β, where α = 539 and β=5.2, which will inform our in vivo studies. Inputting these rates into a mathematical model to predict optimal treatment schedule, our in silico analysis suggest that high dose pulse treatment of INCB18424 has the same efficacy as chronic dosing and is associated with reduced toxicity. We are currently testing our dosing and administration schedules using in vivo models of MPN, and we will present these data at the meeting. Preliminary studies suggest intermittent JAK inhibition shows similar efficacy as chronic JAK inhibition, with reduced toxicity, suggesting our in silico models inform the development of more optimal dosing regimens. We are now testing higher doses of JAK inhibitors in an intermittent administration regimen in order to maximize efficacy and mitigate hematologic and non-hematologic toxicity. In conclusion, our proof-of-principle studies show that intermittent treatment with JAK kinase inhibitors demonstrates equivalent efficacy in vitro and our in silico data suggests that we will see reduced toxicity with intermittent dosing in the mouse models. Our in vivo data will inform further clinical optimization of treatment regiments for patients with myeloproliferative neoplasms Disclosures Koppikar: Amgen: Employment. Levine:Novartis: Consultancy, Grant support Other.

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Nevirapine (NVP) was the first nonnucleoside reverse transcriptase inhibitor (NNRTI) approved by the US Food and Drug Administration (FDA) in 1996, for the treatment of HIV infection. Current treatment guidelines include NVP as a component of a recommended alternative NNRTI regimen, which may be the preferred regimen for patients with established cardiovascular risk factors since NVP has minimal untoward effects on serum lipids. Two randomized and controlled clinical trials established the noninferior virologic efficacy of twice-daily NVP versus ritonavir-boosted atazanavir (ATV/r), a protease inhibitor with limited effects on serum lipids, each drug on a background regimen of once-daily (QD) tenofovir (TDF)/emtricitabine (FTC). An extended-release (XR) formulation of NVP was developed since QD dosing and reduced pill burdens have been shown to improve regimen adherence. This formulation (Viramune XR 400 mg) was recently FDA approved based on the results of 2 randomized, controlled clinical trials. The XR formulation will provide additional treatment options for patients who may benefit from NVP-based regimens.

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ABSTRACTIncreasing evidence suggests that colistin monotherapy is suboptimal at currently recommended doses. We hypothesized that front-loading provides an improved dosing strategy for polymyxin antibiotics to maximize killing and minimize total exposure. Here, we utilized anin vitropharmacodynamic model to examine the impact of front-loaded colistin regimens against a high bacterial density (108CFU/ml) ofPseudomonas aeruginosa. The pharmaco*kinetics were simulated for patients with hepatic (half-life [t1/2] of 3.2 h) or renal (t1/2of 14.8 h) disease. Front-loaded regimens (n= 5) demonstrated improvement in bacterial killing, with reduced overall free drug areas under the concentration-time curve (fAUC) compared to those with traditional dosing regimens (n= 14) with various dosing frequencies (every 12 h [q12h] and q24h). In the renal failure simulations, front-loaded regimens at lower exposures (fAUC of 143 mg · h/liter) obtained killing activity similar to that of traditional regimens (fAUC of 268 mg · h/liter), with an ∼97% reduction in the area under the viable count curve over 48 h. In hepatic failure simulations, front-loaded regimens yielded rapid initial killing by up to 7 log10within 2 h, but considerable regrowth occurred for both front-loaded and traditional regimens. No regimen eradicated the high bacterial inoculum ofP. aeruginosa. The current study, which utilizes anin vitropharmacodynamic infection model, demonstrates the potential benefits of front-loading strategies for polymyxins simulating differential pharmaco*kinetics in patients with hepatic and renal failure at a range of doses. Our findings may have important clinical implications, as front-loading polymyxins as a part of a combination regimen may be a viable strategy for aggressive treatment of high-bacterial-burden infections.

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After a decade of dolutegravir (DTG) use in various antiretroviral therapy combinations and in diverse populations globally, it is critical to identify HIV strains with reduced drug susceptibility and monitor emergent resistance in people living with HIV who experience virologic failure while on DTG-based regimens. We searched the PubMed, Embase, and Cochrane databases to identify studies that reported DTG resistance-associated mutations (RAMs) emerging under selection pressure. Our review showed that RAMs conferring resistance to DTG were rare in 2-drug and 3-drug regimens used in real-world cohorts, corroborating data from clinical trials. The potency of DTG in maintaining virologic suppression was demonstrated, even in cases of pre-existing resistance to companion drugs in the regimen. Estimates of DTG RAMs depended on the population and certain risk factors, including monotherapy, baseline resistance or lack of genotypic testing, treatment history and prior virologic failure, and suboptimal treatment adherence. The RAMs detected after virologic failure, often in heavily treatment-experienced individuals with prior exposure to integrase strand transfer inhibitors, were G118R, E138K, G140A/C/R/S, Q148H/K/R, N155H, and R263K. Overall, these data highlight the durable effectiveness and high barrier to resistance of DTG as part of combination antiretroviral therapy in a wide variety of settings.

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ABSTRACTSafe, effective concomitant treatment regimens for tuberculosis (TB) and HIV infection are urgently needed. Bedaquiline (BDQ) is a promising new anti-TB drug, and efavirenz (EFV) is a commonly used antiretroviral. Due to EFV's induction of cytochrome P450 3A4, the metabolic enzyme responsible for BDQ biotransformation, the drugs are expected to interact. Based on data from a phase I, single-dose pharmaco*kinetic study, a nonlinear mixed-effects model characterizing BDQ pharmaco*kinetics and interaction with multiple-dose EFV was developed. BDQ pharmaco*kinetics were best described by a 3-compartment disposition model with absorption through a dynamic transit compartment model. Metabolites M2 and M3 were described by 2-compartment models with clearance of BDQ and M2, respectively, as input. Impact of induction was described as an instantaneous change in clearance 1 week after initialization of EFV treatment and estimated for all compounds. The model predicts average steady-state concentrations of BDQ and M2 to be reduced by 52% (relative standard error [RSE], 3.7%) with chronic coadministration. A range of models with alternative structural assumptions regarding onset of induction effect and fraction metabolized resulted in similar estimates of the typical reduction and did not offer a markedly better fit to data. Simulations to investigate alternative regimens mitigating the estimated interaction effect were performed. The results suggest that simple adjustments of the standard regimen during EFV coadministration can prevent reduced exposure to BDQ without increasing exposures to M2. However, exposure to M3 would increase. Evaluation in clinical trials of adjusted regimens is necessary to ensure appropriate dosing for HIV-infected TB patients on an EFV-based regimen.

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Abstract Allogeneic stem cell transplantation is an increasingly important treatment option in patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Although there has been substantial progress in reducing transplantation-related mortality (TRM), little progress has been made in reducing the risk of disease relapse, which continues to represent the major cause of treatment failure in patients allografted for AML and MDS. Experience with myeloablative conditioning regimens has demonstrated that, although intensification of the preparative regimen reduces relapse risk, any survival benefit is blunted by a concomitant increase in TRM. A similar inverse correlation between relapse risk and TRM is observed in patients allografted using a reduced-intensity conditioning regimen. However, the markedly lower toxicity of such regimens has permitted the design of novel conditioning strategies aimed at maximizing antitumor activity without excessive transplant toxicity. Coupled with recent advances in drug delivery and design, this has allowed the development of a spectrum of new conditioning regimens in patients with high-risk AML and MDS. At the same time, the optimization of a graft-versus-leukemia (GVL) effect by minimizing posttransplantation immunosuppression, with or without the infusion of donor lymphocytes, is essential if the risk of disease relapse is to be reduced. Recently, the delivery of adjunctive posttransplantation therapies has emerged as a promising method of augmenting antileukemic activity, either through a direct antitumor activity or consequent upon pharmacological manipulation of the alloreactive response. Taken together these advances present a realistic possibility of delivering improved outcome in patients allografted for high-risk AML or MDS.

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Drug-drug interaction is an event that occurs when the effects of one drug modified by another drug or food when taken concurrently or concomitantly. This interaction either reduced the effect or no effect or increased drug effect. Patient in intensive care unit (ICU) are highly susceptible to drug interactions because of the complexity of the drugs regimens they receive. Drugs may affect the Pharmaco*kinetics of the critical ill patients and subsequently altered the pharmacological response, which potentially lead to serious adverse drug events. Drug-drug interaction (DDI) are considered predictable and thus avoidable and manageable.

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ABSTRACTHere we describe an experimental murine model that allows for aerosolized antituberculosis drug efficacy testing. Intrapulmonary aerosol delivery of isoniazid, capreomycin, and amikacin to mice with pulmonary infection ofMycobacterium tuberculosisdemonstrated efficacy in reducing pulmonary bacterial loads similar to that seen by standard drug delivery methods, even when lower concentrations of drugs and fewer doses were used in the aerosolized drug regimens. Interestingly, intrapulmonary delivery of isoniazid also reduced the bacterial load in the spleen.

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Information on drug absorption and disposition in infants and children has increased considerably over the past 2 decades. However, the impact of specific age-related effects on pharmaco*kinetics, pharmacodynamics, and dose requirements remains poorly understood. Absorption can be affected by the differences in gastric pH and stomach emptying time that have been observed in the pediatric population. Low plasma protein concentrations and a higher body water composition can change drug distribution. Metabolic processes are often immature at birth, which can lead to a reduced clearance and a prolonged half-life for those drugs for which metabolism is a significant mechanism for elimination. Renal excretion is also reduced in neonates due to immature glomerular filtration, tubular secretion, and reabsorption. Limited data are available on the pharmacodynamic behavior of drugs in the pediatric population. Understanding these age effects provide a mechanistic way to identify initial doses for the pediatric population. The various factors that impact pharmaco*kinetics and pharmacodynamics mature towards adult values at different rates, thus requiring continual modification of drug dose regimens in neonates, infants, and children. In this paper, the age-related changes in drug absorption, distribution, metabolism, and elimination in infants and children are reviewed, and the age-related dosing regimens for this population are discussed.

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We carried out a cohort retrospective study to justify the possibilities to continue the main TB treatment course in adolescents with determined drug susceptibility during treatment (without return to treatment commencement) in order to reduce the total duration of treatment. Out of 123 patients who completed treatment in 2019–2022 we selected 31 patients with drug susceptibility test (DST) results obtained by only cultural studies using BACTEC MGIT 960 after 1.5-2 months of treatment. We established that DST results obtained using BACTEC MGIT 960 during treatment would determine further treatment tactics. We compared two groups of patients. Group 1 included 17 patients susceptible to at least 3 TB drugs and positive clinical and X-ray dynamics; their treatment regimens were corrected without return to the intensive phase. Group 2 included 14 patients susceptible to 1-2 TB drugs of the administered regimen without positive clinical and X-ray dynamics; after treatment correction they received the intensive phase of treatment again. The comparison of the main chemotherapy course duration showed that the patients of group 2 received treatment for a significantly longer period of time as compared to the patients of group 1 (the Mann–Whitney U test – 30.5, the critical value 67; р < 0.05).

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The review covers reduced kidney function in the context of renal cell carcinoma. According to international studies, some patients already have chronic kidney disease at time of disease onset. Surgical treatment leads to a decrease in the total number of functioning nephrons. Drug therapy causes several adverse events including nephrotoxicity. The review discusses the problem of using combination regimens in patients with solitary kidney.

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Background: Patients living with HIV (PLWH) with multi-drug resistance (MDR) and prior episodes of virologic failure have few therapeutic options remaining. These patients are often prescribed ‘salvage’ antiretroviral therapy (ART) regimens with high pill burdens, leading to potential decreased medication adherence and increased side effects and drug–drug interactions. Materials & Methods: In this retrospective, observational cohort study, we included adult patients with a diagnosis of HIV-1 who received care at our institution’s Ryan White Clinic and who received ‘salvage’ ART, defined as three of more antiretroviral agents from at least three different HIV drug classes. Patients were grouped into two cohorts, simplified ART cohort and non-simplified ART cohort, based on whether their ART regimen was reduced by at least one tablet daily. The primary outcome was the percentage of patients who had their viral load suppressed (HIV-1 RNA <50 copies/ml) at their most recent clinic visit. Secondary outcomes were virologic failure (HIV-1 RNA ⩾200 copies/ml), percentage of time patients were virologically suppressed over the past 2 years, and the emergence of new treatment-resistant mutations. Results: There were 50 patients included in the final analysis, 28 in the simplified ART cohort and 22 in the non-simplified ART cohort. The percentage of patients who had their HIV-1 viral load suppressed at their most recent clinic visit was n = 24 (86%) in the simplified ART cohort and n = 16 (73%) in the non-simplified ART cohort ( p = 0.302). There were no statistically significant differences between the two cohorts in terms of the secondary outcomes. Conclusion: Our study found that simplification of ART regimens based on HIV genotype in PLWH with a history of MDR and prior virologic failures, regardless of the presence of HIV-1 viremia at the time of simplification, resulted in similar rates of virologic suppression and virologic failure as non-simplified ART regimens.

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Objective: to systematize data on cost-effectiveness evaluation of new multidrug and extensively drug-resistant tuberculosis (MDR/XDR-TB) chemotherapy regimens.Material and methods. An analysis of 19 publications devoted to the economic evaluation of the treatment of active MDR/XDR-TB was carried out. The literature search was performed in the electronic databases PubMed/MEDLINE, Google Scholar, eLibrary for the period from January 2015 to February 2022 inclusively.Results. Economic efficiency was studied in high-, middleand low-income countries. All publications contained calculation of treatment costs, and a third of the studies also estimated additional costs. Bedaquiline, delamanid, and pretomanid regimens were included in treatment alone or compared with a background regimen. The most commonly used economic model was the Markov one. To compare primary outcomes, most studies assessed disabilityand quality-adjusted life years. The overall cost of MDR/XDR-TB treatment varied by country income level. In all cases, bedaquiline-based regimens represented a cost-effective alternative to previous treatment, showed high efficacy in MDR/XDR-TB therapy, and were more cost-effective than delamanid regimens.Conclusion. Cost-effective interventions for active MDR/XDR-TB therapy should include the introduction of new chemotherapy regimens, reduced hospital stays and decentralized treatment, which is especially relevant in countries with high tuberculosis burden.

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Background Emerging evidence suggests that shortened, simplified treatment regimens for rifampicin-resistant tuberculosis (RR-TB) can achieve comparable end-of-treatment (EOT) outcomes to longer regimens. We compared a 6-month regimen containing bedaquiline, pretomanid, linezolid, and moxifloxacin (BPaLM) to a standard of care strategy using a 9- or 18-month regimen depending on whether fluoroquinolone resistance (FQ-R) was detected on drug susceptibility testing (DST). Methods and findings The primary objective was to determine whether 6 months of BPaLM is a cost-effective treatment strategy for RR-TB. We used genomic and demographic data to parameterize a mathematical model estimating long-term health outcomes measured in quality-adjusted life years (QALYs) and lifetime costs in 2022 USD ($) for each treatment strategy for patients 15 years and older diagnosed with pulmonary RR-TB in Moldova, a country with a high burden of TB drug resistance. For each individual, we simulated the natural history of TB and associated treatment outcomes, as well as the process of acquiring resistance to each of 12 anti-TB drugs. Compared to the standard of care, 6 months of BPaLM was cost-effective. This strategy was estimated to reduce lifetime costs by $3,366 (95% UI: [1,465, 5,742] p < 0.001) per individual, with a nonsignificant change in QALYs (−0.06; 95% UI: [−0.49, 0.032] p = 0.790). For those stopping moxifloxacin under the BPaLM regimen, continuing with BPaL plus clofazimine (BPaLC) provided more QALYs at lower cost than continuing with BPaL alone. Strategies based on 6 months of BPaLM had at least a 93% chance of being cost-effective, so long as BPaLC was continued in the event of stopping moxifloxacin. BPaLM for 6 months also reduced the average time spent with TB resistant to amikacin, bedaquiline, clofazimine, cycloserine, moxifloxacin, and pyrazinamide, while it increased the average time spent with TB resistant to delamanid and pretomanid. Sensitivity analyses showed 6 months of BPaLM to be cost-effective across a broad range of values for the relative effectiveness of BPaLM, and the proportion of the cohort with FQ-R. Compared to the standard of care, 6 months of BPaLM would be expected to save Moldova’s national TB program budget $7.1 million (95% UI: [1.3 million, 15.4 million] p = 0.002) over the 5-year period from implementation. Our analysis did not account for all possible interactions between specific drugs with regard to treatment outcomes, resistance acquisition, or the consequences of specific types of severe adverse events, nor did we model how the intervention may affect TB transmission dynamics. Conclusions Compared to standard of care, longer regimens, the implementation of the 6-month BPaLM regimen could improve the cost-effectiveness of care for individuals diagnosed with RR-TB, particularly in settings with a high burden of drug-resistant TB. Further research may be warranted to explore the impact and cost-effectiveness of shorter RR-TB regimens across settings with varied drug-resistant TB burdens and national income levels.

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Background Globally, drug resistant tuberculosis (DR-TB) continues to be a public health threat. Nigeria, which accounts for a significant proportion of the global burden of rifampicin/multi-drug resistant-TB (RR/MDR-TB) had a funding gap of $168 million dollars for TB treatment in 2018. Since 2010, Nigeria has utilized five different models of care for RR/MDR-TB (Models A-E); Models A, B and C based on a standardized WHO-approved treatment regimen of 20–24 months, were phased out between 2015 and 2019 and replaced by Models D and E. Model D is a fully ambulatory model of 9–12 months during which a shorter treatment regimen including a second-line injectable agent is utilized. Model E is identical to Model D but has patients hospitalized for the first four months of care while Model F which is to be introduced in 2020, is a fully ambulatory, oral bedaquiline-containing shorter treatment regimen of 9–12 months. Treatment models for RR/MDR-TB of 20–24 months duration have had treatment success rates of 52–66% while shorter treatment regimens have reported success rates of 85% and above. In addition, replacing the second-line injectable agent in a shorter treatment regimen with bedaquiline has been found to further improve treatment success in patients with fluoroquinolone-susceptible RR/MDR-TB. Reliable cost data for RR/MDR-TB care are limited, specifically costs of models that utilize shorter treatment regimens and which are vital to guide Nigeria through the provision of RR/MDR-TB care at scale. We therefore conducted a cost analysis of shorter treatment regimens in use and to be used in Nigeria (Models D, E and F) and compared them to three models of longer duration utilized previously in Nigeria (Models A, B and C) to identify any changes in cost from transitioning from Models A-C to Models D-F and opportunities for cost savings. Methods We obtained costs for TB diagnostic and monitoring tests, in-patient and out-patient care from a previous study, inflated these costs to 2019 NGN and then converted to 2020 USD. We obtained other costs from the average of six health facilities and drug costs from the global drug facility. We modeled treatment on strict adherence to two Nigerian National guidelines for programmatic and clinical management of drug-resistant tuberculosis. Results We estimated that the total costs of care from the health sector perspective for Models D, E and F were $4,334, $7,705 and $3,420 respectively. This is significantly lower than the costs of Models A, B and C which were $14,781, $12, 113, $7,572 respectively. Conclusion Replacing Models A–C with Models D and E reduced the costs of RR/MDR-TB care in Nigeria by approximately $5,470 (48%) per patient treated and transitioning from Models D and E to Model F would result in further cost savings of $914 to $4,285 (21 to 56%) for every patient placed on Model F. If the improved outcomes of patients managed using bedaquiline-containing shorter treatment regimens in other countries can be attained in Nigeria, Model F would be the recommended model for the scale up of RR/MDR-TB care in Nigeria.

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PURPOSE The combination of suramin and hydrocortisone has shown clinical benefit in patients with androgen-independent prostate cancer. Widespread use was limited by the complex dose schedules and the need for pharmacologic monitoring. This study reports three sequential pharmaco*kinetically derived treatment regimens that simplified the administration of suramin and hydrocortisone with reduced toxicity. PATIENTS AND METHODS Three cohorts of patients with advanced prostate cancer that progressed despite castrate levels of testosterone received oral hydrocortisone plus suramin administered in the following manners: (1) a loading dose of suramin followed by a continuous infusion using an adaptive control program (cohort A); (2) an intermittent schedule using a simplified adaptive control schedule (cohort B); and (3) an empiric dosing regimen (cohort C). Drug concentrations were monitored along with the toxicities associated with each regimen. Efficacy was assessed using measurable-disease criteria, radionuclide scans, and posttherapy changes in prostate-specific antigen (PSA) levels. RESULTS Fifty-six patients were treated and plasma suramin concentrations were similar for each regimen. A partial response was observed in 4% (one of 28; 95% confidence interval, 0% to 18.4%) of patients with measurable disease, while 12% (six of 50; 95% confidence interval, 4.5% to 24.3%) had a greater than 80% decline in the baseline PSA level. The median duration of response was 12 months. No responses on radionuclide scans were seen. Anemia and lymphocytopenia were the most common toxicities, while 7% of patients developed a sensory or motor neurotoxicity. In the sequential regimens, the frequency of renal insufficiency (P = .04) and coagulopathy (P < .0001) decreased, while transaminase elevations (P = .05) were more common using intermittent infusions (cohorts B and C) versus continuous infusion schedules (cohort A). CONCLUSION The administration of suramin was simplified and the drug concentrations were maintained. In this cohort of patients with advanced prostate cancer, the clinical activity of suramin using these dosing schedules was limited. Pharmacodynamic issues, patients selection, and criteria to assess efficacy could have effected the clinical outcome.

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Abstract The combination of high-dose busulfan (16 mg/kg) and 200 mg/kg cyclophosphamide is gaining increasing significance as a preparative regimen prior to autologous, syngeneic, or allogeneic marrow transplantation. A new regimen of high-dose busulfan in conjunction with a reduced dose of 120 mg/kg cyclophosphamide has recently been described as a preparative regimen prior to allogeneic transplantation. To determine the drug-related nonhematologic toxic effects of this new regimen without confounding factors associated with allogeneic transplantation, we conducted a pilot study using this new regimen in 20 patients with acute myeloid leukemia (AML) in first remission prior to autologous unpurged marrow transplantation. All patients experienced transient non-life-threatening acute drug-related toxicity with skin reactions in 20 (100%), nausea and vomiting in 20 (100%), oral mucositis in 18 (90%), hepatic functional impairment in 17 (85%), hemorrhagic cystitis in three (15%), and generalized seizures in two (10%) of these patients, respectively. Two procedural, fatal complications resulted from infectious causes that were not directly related to the speed of hematopoietic reconstitution or the toxicity of the preparative regimen. The 3-year event-free survival estimate (55% +/- 11%) and probability of leukemic recurrence (38% +/- 11%) attained with this new regimen in recipients of autografts in first remission of AML are promising and challenge comparisons with preparative regimens employing combinations of cytotoxic agents or total body irradiation (TBI).

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The combination of high-dose busulfan (16 mg/kg) and 200 mg/kg cyclophosphamide is gaining increasing significance as a preparative regimen prior to autologous, syngeneic, or allogeneic marrow transplantation. A new regimen of high-dose busulfan in conjunction with a reduced dose of 120 mg/kg cyclophosphamide has recently been described as a preparative regimen prior to allogeneic transplantation. To determine the drug-related nonhematologic toxic effects of this new regimen without confounding factors associated with allogeneic transplantation, we conducted a pilot study using this new regimen in 20 patients with acute myeloid leukemia (AML) in first remission prior to autologous unpurged marrow transplantation. All patients experienced transient non-life-threatening acute drug-related toxicity with skin reactions in 20 (100%), nausea and vomiting in 20 (100%), oral mucositis in 18 (90%), hepatic functional impairment in 17 (85%), hemorrhagic cystitis in three (15%), and generalized seizures in two (10%) of these patients, respectively. Two procedural, fatal complications resulted from infectious causes that were not directly related to the speed of hematopoietic reconstitution or the toxicity of the preparative regimen. The 3-year event-free survival estimate (55% +/- 11%) and probability of leukemic recurrence (38% +/- 11%) attained with this new regimen in recipients of autografts in first remission of AML are promising and challenge comparisons with preparative regimens employing combinations of cytotoxic agents or total body irradiation (TBI).

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Abstract Background Antiretroviral therapy (ART) is critical for ending the HIV epidemic. Tenofovir-containing ART is the first-line regimen in many countries including South Africa, with limited access to second-line ART. High levels of drug resistance have been reported among patients after virologic failure on tenofovir-containing first-line regimens (TenoRes Study, Lancet Infect Dis 2016). We assessed drug resistance at the population level using mathematical modeling. Methods We developed a stochastic individual-based model of the heterosexual HIV epidemic in KwaZulu-Natal South Africa, and compared drug resistance from scenarios of tenofovir-containing ART scale-up, either CD4-based (threshold &lt; 500 cells/mL) or Fast-track (80% coverage by 2020). The model represents details of HIV transmission and disease progression, demography, sexual behavior, condom use, circumcision, treatment interventions and drug resistance dynamics including key mutations (M184V, K65R and non-nucleoside reverse transcriptase inhibitor (NNRTI)). Using an initial population of 2.5 million, we performed 100 simulations from 1978 to 2030. We examined the prevalence of (majority) transmitted and acquired resistance by 2030. Results The total resistance (proportion of HIV-infected persons with drug resistance) reached 34% from CD4-based ART by 2030, with 30% relative contribution from transmitted resistance and 70% from acquired resistance. In contrast, Fast-track ART reduced the total resistance to 22%; though, there was an increased relative contribution from transmitted resistance (~ 50%). In both scenarios, NNRTI mutations were the most prevalent, followed by M184V and K65R mutations. About 48% of persons with acquired drug- resistance harbored dual drug mutations, 44.7% had triple mutations and 7.3% just single mutations, from CD4-based ART. The respective estimates from Fast-track ART were similar; 49% for dual, 44.1% for triple and 6.9% for single mutations. In both scenarios, NNRTI mutations comprised about 80% of prevalent transmitted resistance. Conclusion Current WHO-recommended first-line ART could lead to substantial drug resistance. Effective surveillance for resistance transmission and access to second-line regimens would be crucial. Disclosures All authors: No reported disclosures.

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Abstract Introduction: Rigosertib is a small molecule inhibitor of cellular signaling pathways in cancer cells by acting as a Ras mimetic. The inhibitory effect is mediated by Rigosertib binding to the Ras-binding domain found in many Ras effector proteins (Athuluri-Divakar SK, Cell 2016). Oral administration of Rigosertib was initially evaluated in lower risk MDS patients. The drug, administered as 560 mg BID (q12hr; 2/3 wks), was associated with high rates of transfusion independence but with significant GU AEs (Raza, et al, Blood 2017 130:1689). Subsequently, a reduction in the PM dose to 280 mg led to a decrease in GU AEs, suggesting a causal relationship with nocturnal bladder drug concentration. When oral administration of Rigosertib was tested with standard dose of parenteral Azacitidine in a Phase I/II trial (NCT01926587) at a dose of 560/280 mg (Q12hrs, 3/4 weeks), the ORR was 77%; with 60% for the HMA relapsed/refractory group for the high risk MDS patients. The impressive response rate, in the combination treatment, was also associated with significant GU AEs. Hence, it is important to understand the underlying cause and devise ways to maximize response rates with minimization of GU AEs. Previously, it was established that GU AEs were unlikely to be related to the higher systemic exposure of the drug (Maniar, et al ASH 2018, Abstract submitted) but attributed to the nocturnal dwell time of high drug concentration in the bladder of patients treated with continuous oral administration (3/4 weeks). In this investigation, we developed a pharmaco*kinetic model to simulate the systemic and bladder exposure of Rigosertib after repeated oral dosing. The overall aim was to identify and implement an oral dosing regimen for Rigosertib that would maximize the systemic exposure with minimization of nocturnal bladder concentration, thereby potentially mitigating or eliminating the GU AE's. Methods: A 2-compartment model with 1st order absorption and elimination (Figure 1) was fitted to data collected from patients with solid malignancies at a 560 mg dose (n=25). Model parameter estimates were then used to generate a virtual population of 100 patients. Each virtual patient was randomly assigned parameter values based on the 95% confidence interval for each parameter estimate obtained through the modeling analysis. Model simulations were then performed to evaluate the steady state systemic and urinary exposure of Rigosertib in the virtual population after treatment with different dosing schedules (Figure 2). Besides plasma exposure (Cmax, AUC), the predicted rigosertib bladder concentration during the sleep-cycle was also assessed. From this analysis, optimal dosing regimens were selected for evaluation in a Phase 2 study in HR-MDS patients in combination with Azacitidine. The model was validated by comparing the predicted systemic exposure with observed data using these optimal dosing regimens, and by comparing Grade 3 GU AE's events from the pre- and post-optimization of dosing regimen (NCT01926587). Results: The model-predicted steady state plasma concentration-time profile of Rigosertib for different dosing regimens is shown in Figure 3. The duration of exposure of drug above minimum effective concentration (MEC, 0.175 ug/ml) was not changed by varying the dosing regimen. Importantly, model simulations demonstrated that BID dosing, with the dosing interval of 8 hours, would reduce the bladder concentration of Rigosertib by as much as 70% during sleep without compromising systemic drug exposure (Table 1). As illustrated in Table 2, model simulated Rigosertib exposure (Cmax, AUC) compared favorably with data from patients treated with the novel twice daily dosing regimens (560mg/560mg and 840 mg/280mg, dosing interval of 8 hours), thereby validating the model. Preliminary safety data from the on-going trial demonstrates that the Grade 3 GU AEs were significantly reduced (12%) with the optimized dosing regimen compared to the pre-optimized dosing regimen (29%) despite using a higher total dose of drug (1120 mg vs 840 mg). Conclusions: This study demonstrates the utility of pharmaco*kinetic modeling for designing a dosing regimen directed at reducing the incidence of toxicity. The identified dosing regimen, along with mitigation strategies, successfully reduced the risk of Grade 3 GU AEs of rigosertib without compromising the duration of systemic exposure of Rigosertib above MEC in HR MDS patients. Disclosures Taft: Onconova Therapeutics, Inc: Research Funding. Ren:Onconova Therapeutics, Inc: Employment, Equity Ownership. Zbyszewski:Onconova Therapeutics, Inc: Employment, Equity Ownership. Morgan:Onconova Therapeutics, Inc: Consultancy. Petrone:Onconova Terapeutics Inc.: Employment, Equity Ownership. Fruchtman:Onconova Therapeutic Inc: Employment, Equity Ownership. Maniar:Onconova Therapeutics, Inc: Employment, Equity Ownership.

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Background The treatment success rate of conventional anti-tuberculosis (TB) regimens for extensively drug-resistant TB (XDR-TB) is low, resulting in high morbidity and healthcare cost especially in the high TB burden countries. Recent clinical findings reported improved treatment outcomes of XDR-TB with the bedaquiline (BDQ)-based regimens. We aimed to evaluate the cost-effectiveness of BDQ-based treatment for XDR-TB from the perspective of the South Africa national healthcare provider. Methods A 2-year decision-analytic model was designed to evaluate the clinical and economic outcomes of a hypothetical cohort of adult XDR-TB patients with (1) BDQ-based regimen and (2) injectable-based conventional regimen. The model inputs were retrieved from literature and public data. Base-case analysis and sensitivity analysis were performed. The primary model outputs included TB-related direct medical cost and disability-adjusted life years (DALYs). Results In the base-case analysis, the BDQ group reduced 4.4152 DALYs with an incremental cost of USD1,606 when compared to the conventional group. The incremental cost per DALY averted (ICER) by the BDQ group was 364 USD/DALY averted. No influential factor was identified in the sensitivity analysis. In probabilistic sensitivity analysis, the BDQ group was accepted as cost-effective in 97.82% of the 10,000 simulations at a willingness-to-pay threshold of 5,656 USD/DALY averted (1× gross domestic product per capita in South Africa). Conclusion The BDQ-based therapy appeared to be cost-effective and showed a high probability to be accepted as the preferred cost-effective option for active XDR-TB treatment.

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430 Background: Anticancer drug regimens that are approved by accepted drug compendia and also considered high value based on their efficacy, toxicity, and costs are designated as “on-pathway” for a national commercial payer. This study compared quality and cost of cancer care among patients with metastatic solid tumors treated in the first line setting who were prescribed on- vs. off-pathway regimens. Methods: Using administrative claims data and prior authorization data from a national commercial payer, we identified 8,357 commercially insured or Medicare Advantage adult patients with solid tumor cancers including breast, lung, colorectal, pancreatic, melanoma, kidney, bladder, gastric, or uterine cancer, who were prescribed first-line anti-cancer regimens in the metastatic setting from 2018 to 2021. Patients were classified into on- vs. off pathway group based on the initial anticancer regimen that was prescribed. On-pathway status was prospectively defined by a panel of practicing oncologists based on review of curated evidence and general application of relative clinical value frameworks accepted in the field. We compared post–6-month quality-of-care outcomes including chemotherapy-related avoidable hospitalizations, emergency room (ER) visits, immune-related adverse events (IRAEs) such as endocrinopathies owing to immune checkpoint inhibitors, need for supportive drugs such as granulocyte colony stimulating factor, and cost outcomes between groups. Generalized linear models were used to assess the association between on-pathway regimens and outcomes adjusting for key patient demographics, clinical and provider characteristics. Results: A total of 5,453 (65.3%) patients were prescribed on-pathway regimens. Both groups had similar age (60.1 vs. 59.6, p = 0.06) and ECOG performance status (0.63 vs. 0.62, p = 0.40), with more females in the off-pathway group (54.6% vs. 57.3%, p = 0.02). There was no statistically significant difference in chemotherapy-related avoidable hospitalizations, IRAEs and need for supportive drugs between the two groups after modeling adjustment. However, patients treated on-pathway had higher rates of chemotherapy-related avoidable ER visits (18% vs. 15%, adjusted odds ratio: 1.16, 95% confidence interval (CI): 1.01 to 1.33, p = 0.03). Patients in the on-pathway group had significantly lower 6-month anticancer treatment cost (adjusted cost difference: -$10410, 95% CI: -$14935 to -$5886, p < 0.01), resulting in an overall lower total healthcare costs (adjusted cost difference: -$12826, 95% CI: -$18879 to -$6773, p < 0.01). Conclusions: Pathway regimens for metastatic solid tumors were associated with reduced total healthcare costs and similar quality of care compared with off-pathway regimens. These findings support the use of high value, evidence-based regimens for metastatic cancer patients.

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ABSTRACTThe experimental compound TMC207 is showing promise against infections caused byMycobacterium tuberculosisboth in a variety of animal studies and in the field. In this study, we used the guinea pig model, a species that shows several similarities to human tuberculosis, including the hallmark of primary granuloma necrosis, to determine the efficacy of a combination regimen combining TMC207 with rifampin and pyrazinamide. This drug regimen rapidly reduced the bacterial load in the lungs to undetectable levels by 8 weeks of treatment. This reduction was associated with a substantial improvement in lung pathology, but despite this effect areas of residual necrosis still remained. In the draining lymph nodes, however, tissue damage was rapid and not significantly reversed by the drug treatment. Approximately 10 to 11 months after the treatment had ended, the animals began to trigger a Karnovsky scale indicating bacterial regrowth and potential relapse, an event confirmed by the new development of both pulmonary and extrapulmonary granulomatous lesions. Interestingly, a similar rate of relapse was also seen in animals receiving 24 weeks of rifampin, pyrazinamide, and isoniazid standard chemotherapy. These data indicate that TMC207 could be a useful addition to current treatment regimens for tuberculosis.

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Objective Information about the virological response to sequential highly active antiretroviral therapy (HAART) for HIV infection is limited. The virological response to four consecutive therapies was evaluated in the Swiss HIV Cohort. Design Retrospective analysis in an observational cohort. Methods 1140 individuals receiving uninterrupted HAART for 4.8 ±0.6 years were included. The virological response was classified as success (<400 copies/ml), low-level (LF: 400–5000 copies/ml) or high-level failure (HF: >5000 copies/ml). Potential determinants of the virological response, including patient demographics, treatment history and virological response to previous HAART regimens were analysed using survival and logistic regression analyses. Results 40.1% failed virologically on the first (22.0% LF; 18.1% HF), 35.1% on the second (14.2% LF; 20.9% HF), 34.2% on the third (9.9% LF; 24.3% HF) and 32.7% on the fourth HAART regimen (9% LF; 23.7% HF). Nucleoside pre-treatment (OR: 2.34; 95% CI: 1.67–3.29) and low baseline CD4 T-cell count (OR: 0.79/100 cells rise; 95% CI: 0.72–0.88) increased the risk of HF on the first HAART. Virological failure on HAART with HIV-1 RNA levels exceeding 1000 copies/ml predicted a poor virological response to subsequent HAART regimens. A switch from a protease inhibitor- to a non-nucleoside reverse transcriptase inhibitor-containing regimen significantly reduced the risk of HF. Multiple switches of HAART did not affect the recovery of CD4 T lymphocytes. Conclusion Multiple sequential HAART regimens do not per se reduce the likelihood of long-term virological suppression and immunological recovery. However, early virological failure increases significantly the risk of subsequent unfavourable virological responses. The choice of a potent initial antiretroviral drug regimen is therefore critical. This study has been presented in part at the 10th Conference on Retroviruses & Opportunistic Infections. Boston, Mass., USA, 2003. Abstract #571.

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Abstract Precision dosimetry with TBI has facilitated definition of maximal and minimal limits for dose intensity in HSCT preparative regimens assuring more predictable toxicity and therapeutic benefit than high dose chemotherapy preparative regimens, where 3–5 fold variation in drug level achieved with a given dose directly results in more variable outcome in both toxicity and disease control. BU is the most widely used drug in preparative regimens for allogeneic (allo) HSCT and is used in autologous (auto) HSCT as well, despite the fact that at standard doses of the drug given po the range of levels achieved include levels associated with fatal toxicity at the high end and relapse at the low end. It has long been recognized that BU pharmaco*kinetics (PK) are simple; the drug is active only as the parent compound, it is rapidly distributed in total body water, it’s metabolism has a single metabolic pathway, and there are no active metabolites. Thus its PK are fully described as single compartment, first order elimination. However, PK directed therapy has been difficult because the oral preparation has of highly variable absorption between patients and between doses. Use of the iv formulation has permitted the development of limited sampling strategies and improved intra-patient predictability. We have developed a specific limited sampling strategy which provides excellent fit to model and has been validated against historical data. We have identified significant concomitant medication effects. We have now studied 51 consecutive patients (pt) receiving BU based preparative regimens adjusting dose 2 of the standard 16 dose regimen based upon the AUC for the first dose given as a test dose 48 hr prior to the remaining 15 given in the standard Q6h intervals. The pt ranged in age from 18–69 (med 44) and in weight from 47–166 Kg (med 84). The preparative regimens consisted of Bu plus cyclophosphamide (Cy) and etoposide for 18 auto HSCT, and 2 haplo-identical allo HSCT, Bu plus fludarabine for 15 matched related donor allo HSCT, and BuCy for 16 matched unrelated donor allo HSCT. Using a single laboratory, careful monitoring for outliers due to concomitant medications and other sources of error, and a fixed dose in mg for all pt, we have reduced the AUC range from 34–164% of target level for dose 1 to 71–130% of target level for dose 2. After removal of 7 predictable outliers due to concomitant meds (4 pt), capping of dose adjustment at 130% of 0.8mg/Kg (2 pt), and sampling error (1 pt), we achieved a range of 73–121% for dose 2. Thus, excluding outliers, 82% of pt could be adjusted to within 90% of target dose and 95% of pt could be adjusted to within 80% of target dose for dose 2. No pt, including the outliers, had dose 2 Bu level in either the range associated with high risk of regimen related mortality or associated with increased risk of relapse. These studies demonstrate that in a routine clinical practice environment, with careful control of concomitant medications, pt can be treated with Bu based preparative regimens achieving levels within 10% of target for over 80% of pt and within 20% of target for over 95%. We conclude that dosing precision with iv busulfan and HSCT preparative regimens is feasible in routine clinical practice and no patient needs to be out of the acceptable range. This dosing precision will improve safety and greatly facilitate dose intensity research in Phase 2 and comparative trials to better define maxi-dose, mini-dose, and “right dose” Bu for use in HSCT preparative regimens for various transplant situations.

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Background People with radiographic evidence for pulmonary tuberculosis (TB), but negative sputum cultures, have increased risk of developing culture-positive TB. Recent expansion of X-ray screening is leading to increased identification of this group. We set out to synthesise the evidence for treatment to prevent progression to culture-positive disease. Methods We conducted a systematic review and meta-analysis. We searched for prospective trials evaluating the efficacy of TB regimens against placebo, observation, or alternative regimens, for the treatment of adults and children with radiographic evidence of TB but culture-negative respiratory samples. Databases were searched up to 18 Oct 2022. Study quality was assessed using ROB 2·0 and ROBINS-I. The primary outcome was progression to culture-positive TB. Meta-analysis with a random effects model was conducted to estimate pooled efficacy. This study was registered with PROSPERO (CRD42021248486). Findings We included 13 trials (32,568 individuals) conducted between 1955 and 2018. Radiographic and bacteriological criteria for inclusion varied. 19·1% to 57·9% of participants with active x-ray changes and no treatment progressed to culture-positive disease. Progression was reduced with any treatment (6 studies, risk ratio [RR] 0·27, 95%CI 0·13–0·56), although multi-drug TB treatment (RR 0·11, 95%CI 0·05–0·23) was significantly more effective than isoniazid treatment (RR 0·63, 95%CI 0·35–1·13) (p = 0·0002). Interpretation Multi-drug regimens were associated with significantly reduced risk of progression to TB disease for individuals with radiographically apparent, but culture-negative TB. However, most studies were old, conducted prior to the HIV epidemic and with outdated regimens. New clinical trials are required to identify the optimal treatment approach.

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Determination of the optimal dose is a critical objective in the drug developmental process. An optimal dose prevents over- and under-exposure to the treatment drug thereby facilitating superior patient experience and reduced costs to the healthcare system. In this paper, we present a method for model-based dose optimisation with simultaneous pharmaco*kinetic estimation of the model parameters. Multiple doses of the drug are considered and the objective is to maintain the blood concentration of the drug around a pre-decided target concentration. We consider an adaptive setting wherein the model parameters are estimated from the blood samples collected at D-optimal time points from all subjects enrolled so far in the trial. The estimated parameters are then used to determine the optimal dose regimen for the next cohort. This procedure continues until the condition of a pre-decided stopping rule is met. Simulation studies and sensitivity analysis are undertaken to validate the methodology. We also evaluate the performance of the methodology when carried out in a non-adaptive setting. A two-stage design is then presented which combines the advantages of the adaptive as well as the non-adaptive approach. We demonstrate that our methodology enables pharmaco*kinetic estimation and dose regimen optimisation simultaneously in an ethical and cost-effective manner protecting the subjects from the ill-effects of suboptimal dose regimens and economising the number of subjects required in the trial.

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Background Shorter, safer, and cheaper tuberculosis (TB) preventive treatment (TPT) regimens will enhance uptake and effectiveness. WHO developed target product profiles describing minimum requirements and optimal targets for key attributes of novel TPT regimens. We performed a cost-effectiveness analysis addressing the scale-up of regimens meeting these criteria in Brazil, a setting with relatively low transmission and low HIV and rifampicin-resistant TB (RR-TB) prevalence, and South Africa, a setting with higher transmission and higher HIV and RR-TB prevalence. Methods and findings We used outputs from a model simulating scale-up of TPT regimens meeting minimal and optimal criteria. We assumed that drug costs for minimal and optimal regimens were identical to 6 months of daily isoniazid (6H). The minimal regimen lasted 3 months, with 70% completion and 80% efficacy; the optimal regimen lasted 1 month, with 90% completion and 100% efficacy. Target groups were people living with HIV (PLHIV) on antiretroviral treatment and household contacts (HHCs) of identified TB patients. The status quo was 6H at 2019 coverage levels for PLHIV and HHCs. We projected TB cases and deaths, TB-associated disability-adjusted life years (DALYs), and costs (in 2020 US dollars) associated with TB from a TB services perspective from 2020 to 2035, with 3% annual discounting. We estimated the expected costs and outcomes of scaling up 6H, the minimal TPT regimen, or the optimal TPT regimen to reach all eligible PLHIV and HHCs by 2023, compared to the status quo. Maintaining current 6H coverage in Brazil (0% of HHCs and 30% of PLHIV treated) would be associated with 1.1 (95% uncertainty range [UR] 1.1–1.2) million TB cases, 123,000 (115,000–132,000) deaths, and 2.5 (2.1–3.1) million DALYs and would cost $1.1 ($1.0–$1.3) billion during 2020–2035. Expanding the 6H, minimal, or optimal regimen to 100% coverage among eligible groups would reduce DALYS by 0.5% (95% UR 1.2% reduction, 0.4% increase), 2.5% (1.8%–3.0%), and 9.0% (6.5%–11.0%), respectively, with additional costs of $107 ($95–$117) million and $51 ($41–$60) million and savings of $36 ($14–$58) million, respectively. Compared to the status quo, costs per DALY averted were $7,608 and $808 for scaling up the 6H and minimal regimens, respectively, while the optimal regimen was dominant (cost savings, reduced DALYs). In South Africa, maintaining current 6H coverage (0% of HHCs and 69% of PLHIV treated) would be associated with 3.6 (95% UR 3.0–4.3) million TB cases, 843,000 (598,000–1,201,000) deaths, and 36.7 (19.5–58.0) million DALYs and would cost $2.5 ($1.8–$3.6) billion. Expanding coverage with the 6H, minimal, or optimal regimen would reduce DALYS by 6.9% (95% UR 4.3%–95%), 15.5% (11.8%–18.9%), and 38.0% (32.7%–43.0%), respectively, with additional costs of $79 (−$7, $151) million and $40 (−$52, $140) million and savings of $608 ($443–$832) million, respectively. Compared to the status quo, estimated costs per DALY averted were $31 and $7 for scaling up the 6H and minimal regimens, while the optimal regimen was dominant. Study limitations included the focus on 2 countries, and no explicit consideration of costs incurred before the decision to prescribe TPT. Conclusions Our findings suggest that scale-up of TPT regimens meeting minimum or optimal requirements would likely have important impacts on TB-associated outcomes and would likely be cost-effective or cost saving.

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Abstract. Thyroidal binding of idoide was studied by kinetic analysis of [123I]iodide uptake and its discharge by perchlorate in 80 hyperthyroid subjects receiving antithyroid drug therapy. Five dosage regimens ranging from 5 mg carbimazole twice daily to 15 mg methimazole twice daily were studied. Binding inhibition was estimated at 5–7 h after drug as an index of the mean effect of the 12 hourly regimen. In all cases, except one in the lowest dose group, binding was found to be markedly reduced with mean binding rates ranging from 0.002 to 0.020 min−1 (normal > 0.15 min−1). The net clearance of iodide in the lowest dose group was reduced to a mean value near the upper limit of the euthyroid range, whereas in the highest dose group it lay at the lower limit of the euthyroid range. These results were reflected in the serum thyroid hormone response. There was a reducing incidence of inadequate control of hyperthyroidism and an increasing incidence of hypothyroidism with increasing thiourylene dose. The exit rate constant of free iodide for the various doses showed values from 0.048 to 0.055 min−1. Corresponding mean values for the discharge rate constant after perchlorate were 0.087 to 0.105 min−1. This suggests that perchlorate increases the rate of iodide release from the thyroid gland. Studies at a later interval after drug (12–14 h) showed no change in discharge rate constant. This leads to the conclusion that perchlorate may further inhibit iodide binding in subjects receiving antithyroid drug therapy.

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DISCUSSION INTRODUCTION Anti thymocyte globulin (ATG) based Graft versus Host disease (GVHD) prophylaxis is widely used for unrelated donor allogeneic hematopoietic cell transplantation (HCT) although the optimal dose remains unclear. Recently, registry based and single centre retrospective analyses have suggested superior outcomes with the PTCy based GVHD prophylaxis regimens when compared to ATG based regimens in mismatched unrelated donor (MMUD) allogeneic HCT, however, these studies all used doses of ATG ≥ 5mg/kg. Outcomes following MMUD allogeneic HCT with lower dose ATG based GVHD prophylaxis regimens have not been extensively studied. Thus, we analysed outcomes of HLA 9/10 MMUD allogeneic HCTs using two low dose ATG based regimens as GVHD prophylaxis at our centre. All adult patients undergoing standard of care allogenic hematopoietic cell transplant at The Ottawa Hospital from January 1 st 2015- December 31, 2022 were included. Data regarding demographics, HLA mismatched allele, conditioning regimen, dose of ATG, time to engraftment, and rates of acute and chronic GVHD was collected. The primary outcome evaluated was overall survival (OS) and secondary outcomes were GVHD-free relapse-free survival (GRFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM). Survival outcomes were analyzed using Kaplan Meier analysis. Predictors of survival were identified using Cox-proportional hazards regression model. 77 patients (Males 62.3% (n=48); Median age - 50 years) underwent allogeneic HCT from MMUD. Most common indication for transplant was MDS/AML in 66.2% (n=51) followed by ALL in 11.3% (n=9) patients. Most frequently mismatched locus was HLA A in 37.7% (n= 29) followed by HLA B in 14.3% (n=11). Myeloablative conditioning regimen was received by 76.6% (n=59) while reduced intensity regimens were used in 23.4% (n=18) patients. Rabbit ATG was part of the GVHD prophylaxis regimen in all patients with majority (81%; n=63) receiving 2.5mg/kg and remaining 18.2% (n=14) receiving 4.5mg/kg of the drug. Grade II-IV acute GVHD occurred in 24.7% (n=19) while chronic GVHD occurred in 32.5% (n= 25) patients. After a median follow up of 21 months, relapse occurred in 28.6% (n=22) patients. Two year OS (Fig 1), and GRFS of the whole cohort were 60.6% and 45.3% respectively. 2-year incidence of non-relapse mortality (NRM) and cumulative incidence of relapse (CIR) were 16.9% and 18.2% respectively. Dose of ATG (2.5 mg/kg vs 4.5 mg/kg) was not a predictor of outcomes in either univariate and multivariate analyses. Age more than 50 years, primary diagnosis of lymphoma, reduced intensity conditioning and mismatch in loci other than HLA C were significant predictors of poor OS after univariate analysis. Only primary diagnosis of lymphoma (Hazard Ratio (HR) - 7.76; p=0.045) and mismatch in loci other than HLA C (HR - 9.53; p=0.03) were significant predictors of poor OS after multivariate analysis. When compared to published single centre and registry-based studies using ATG doses ≥ 5 mg/kg, GVHD prophylaxis using ATG doses ≤4.5 mg/kg seems to provide improved outcomes in patients undergoing allogeneic HCT from mismatched unrelated donors (Table 1). Our findings suggest that further studies are needed directly comparing lower dose ATG based regimens to PTCy based regimens to determine the ideal GVHD prophylaxis regimen for patients undergoing allogeneic HCT from HLA mismatched unrelated donors.

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Introduction: Patients with newly diagnosed multiple myeloma (NDMM) who are ineligible for autologous stem cell transplant (ASCT) tend to have comorbidities and/or advanced age that make this subset of patients difficult to manage with current drug regimens. Methods: A comprehensive literature search of PubMed, Embase, Clinicaltrials.gov and Web of Science was performed from inception and completed on 07/17/2019. Studies focusing on efficacy and tolerability of 3-drug regimens in patients with NDMM were included for the review. Results: Out of 3579 studies, a total of 10 (08 phase II and 03 phase III) clinical trials in last ten years (2010-2019) using 3-drug regimens in NDMM elderly pts (893M/807F) ineligible for ASCT (determined by investigators) were selected. A total of 1703/1740 NDMM pts were evaluated. Proteasome inhibitors (PIs) such as carfilzomib (C), bortezomib (V) and ixazomib (I) showed promising results in elderly transplant-ineligible NDMM pts. CLARION trial (phase III, n=955) compared two PIs (C and V) with melphalan (M) and prednisone. There was no statistically significant difference in progression-free survival (PFS) between two groups (median: 22.3 vs 22.1 months; HR: 0.91; 95% CI, 0.75-1.10, p = 0.159) as well as overall survival (OS) (HR: 1.08; 95% CI: 0.82-1.43). Difference in the least square means of the HR-QoL (Health related- quality of life) was 4.99 (p<.0001) favoring C-group. M may not be an ideal drug to combine with carfilzomib in this setting given more AEs.(Facon et al 2019). V as 3-drug regimen in combination with lenalidomide (L) in 242 pts achieved statistically significant prolonged PFS (median 43 mo) and OS (median 75 mo) with great efficacy and acceptable risk-benefit profile. (Durie et al 2017; phase III). Multinational phase II trial (n=70) by Dimopoulos et al (2019) evaluated I, with different fixed doses of cyclophosphamide (Cy). Median duration was 19 cycles, indicating the long-term tolerability of regimen. With favorable toxicity profile and maintained QoL scores, trial concluded that this therapy is tolerable in elderly transplant-ineligible NDMM pts. Tuchman et al (2017) in phase II trial (n=14) investigated (V-Cy-d) and achieved ORR of 64%, with ≥VGPR of 57%. Low dose V showed great efficacy with M yielding ORR of 86% and VGPR or better of 49% in phase II trial (n=101) that also evaluated Cy as 3-drug combination but results were more productive with M with longer PFS and OS which reduced when impact of frailty was examined on outcomes. Since toxicity was higher with M, trial suggested that 2-drug combination should be preferred in elderly frail patients. (Larocca et al 2015). Efficacy was quite promising when Bringhen et al (2014) trialed C with Cy-d; 87% OS and 76% PFS at 1 y in phase II trial (n=58) with much favorable safety profile. Monoclonal antibodies (mAb) such as elotuzumab (E) and pembrolizumab (Pe) are also tested in elderly. First study conducted on NDMM pts using humanized mAb; E, in phase II trial (n=40) by Takezako et al (2017) attained primary endpoint of the study (ORR) of (88%) and VGPR or better of 45% in Japanese pts with tolerable toxicities in elderly. No subjects on this study experienced severe peripheral neuropathy. KEYNOTE-185; a phase III multinational trial by Usmani et al (2019) evaluated Pe with Ld in 151 pts. FDA halted this study due to unfavorable benefit-risk profile; 19 deaths, 6 due to disease progression (PD), and 13 due to treatment-related AEs. Median PFS and median OS were not reached in either group. Immunomodulators such as L achieved one of the longest PFS reported in a trial of transplant ineligible patients (35 mo) by using LVd regimen in phase II multicenter trial (n=50). (O'Donnell et al 2018) Alkylating agents like bendamustine (ben) and M have been tested in different novel regimens. Decreasing intensity and increasing duration of ben resulted in better outcomes in phase II trial (n=59) by Berdeja et al (2016) and can be given as first line treatment. Ben yielded great results with low dose dexa as compared to high dose achieving 92% ORR. Original regimen was effective but relatively more toxic. Incidence of herpes and neuropathy decreased dramatically with the treatment modifications. Conclusion: Three-drug regimens having PIs, mABs, immunomodulators and alkylating agents have shown desirable results in NDMM transplant (ASCT)-ineligible elderly patients and are likely the emerging standard of care for NDMM. Disclosures Anwer: In-Cyte: Speakers Bureau; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees.

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ABSTRACT The T69D mutation in the human immunodeficiency virus type 1 reverse transcriptase (RT) gene has been associated with reduced susceptibility to dideoxycytosine (ddC); however, several other mutations at codon 69 have been observed in antiretroviral drug-treated patients. The Stanford HIV RT and Protease Sequence Database was interrogated and showed that 23% of patients treated with nucleoside RT inhibitors (NRTI) had mutations at codon 69. These variants included T69N, -S, -A, -G, -E, -I, and -K mutations that were present in patients treated with NRTI but not in drug-naive patients. Treatment history information showed that a substantial percentage of these codon 69 changes occurred in patients administered non-ddC-containing regimens. Different and specific patterns of other RT gene mutations were associated with the various codon 69 mutations. Drug susceptibility assays showed that viral constructs containing codon 69 variants could have reduced susceptibility to ddC and other RT inhibitors. These results suggest that the T69D mutation is not the only codon 69 variant associated with drug resistance and that ddC is not the only drug affected.

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This study aimed to predict the impacts of shorter duration treatment regimens for multidrug-resistant tuberculosis (MDR-TB) on both MDR-TB percentage among new cases and overall MDR-TB cases in the WHO Southeast Asia Region. A deterministic compartmental model was constructed to describe both the transmission of TB and the MDR-TB situation in the Southeast Asia region. The population-level impacts of short-course treatment regimens were compared with the impacts of conventional regimens. Multi-way analysis was used to evaluate the impact by varying programmatic factors (eligibility for short-course MDR-TB treatment, treatment initiation, and drug susceptibility test (DST) coverage). The model predicted that overall TB incidence will be reduced from 246 (95% credible intervals (CrI), 221–275) per 100,000 population in 2020 to 239 (95% CrI, 215–267) per 100,000 population in 2035, with a modest reduction of 2.8% (95% CrI, 2.7%–2.9%). Despite the slight reduction in overall TB infections, the model predicted that the MDR-TB percentage among newly notified TB infections will remain steady, with 2.4% (95% CrI, 2.1–2.9) in 2020 and 2.5% (95% CrI, 2.3–3.1) in 2035, using conventional MDR-TB treatment. With the introduction of short-course regimens to treat MDR-TB, the development of resistance can be slowed by 38.6% (95% confidence intervals (CI), 35.9–41.3) reduction in MDR-TB case number, and 37.6% (95% CI, 34.9–40.3) reduction in MDR-TB percentage among new TB infections over the 30-year period compared with the baseline using the standard treatment regimen. The multi-way analysis showed eligibility for short-course treatment and treatment initiation greatly influenced the impacts of short-course treatment regimens on reductions in MDR-TB cases and percentage resistance among new infections. Policies which promote the expansion of short-course regimens and early MDR-TB treatment initiation should be considered along with other interventions to tackle antimicrobial resistance in the region.

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Abstract Background Patients with cystic fibrosis (CF) experience recurrent bacterial pulmonary exacerbations. The management of these infections becomes increasingly complex due to decreased antimicrobial susceptibility and inadequate pharmaco*kinetic/pharmacodynamic (PK/PD) characterization of the most commonly used antimicrobial agents in this population. Methods One hundred fifty-five pediatric and adult participants receiving cefepime (n=82), meropenem (n=42), or piperacillin-tazobactam (n=31) were enrolled. Opportunistic blood samples were obtained during hospitalization. Population PK (PopPK) analysis was conducted using nonlinear mixed effects modeling in NONMEM, and clinical and demographic characteristics were evaluated as potential covariates. Monte Carlo simulations evaluated the probability of PK/PD target attainment (PTA) for different dosing regimens. Multiple targets, defined as percentage of a 24-h time period that the free drug concentration exceeds the MIC (fT&gt; MIC), were selected based on prior studies of beta-lactam antibiotics. Results Preliminary PopPK modeling results show that lean body weight, creatinine clearance, daily dose, mode of administration (standard vs. extended infusion), and age affect PK parameters, with varying effects by drug. As anticipated, extended or continuous infusions resulted in higher PTA (Table 1). In the cefepime group, the 3-h infusion regimen achieved higher PTAs than the 0.5-h regimen across all age groups. Estimated breakpoints (in which ≥ 90% of patients are expected to achieve a PK/PD target) were 2-4 fold higher in pediatric participants receiving a 3-h infusion vs. 0.5-h infusion, based on age and target fT&gt; MIC. In the meropenem group, increased creatinine clearance led to reduced PTA, and in the piperacillin-tazobactam group, total daily dose and interval were the principal drivers of PTA. Conclusions To our knowledge, this is the largest PopPK study to date of these antimicrobials in individuals with CF. Clinicians should incorporate local antibiograms with these PopPK models to determine optimal dosing in patients with CF, since standard dosing regimens may fail to achieve specific PK/PD targets. This population may also benefit from beta-lactam therapeutic drug monitoring.

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ABSTRACT Mutations selected or deselected during passage of human immunodeficiency virus strain HXB2 or resistant variants with tenofovir (TFV), abacavir (ABC), and lamivudine (3TC) differed depending on the drug combination and virus genotype. In the wild-type virus, TFV-ABC and TFV-3TC selected K65R (with reduced susceptibility to all three inhibitors) and then Y115F. TFV-containing regimens might increase K65R selection, which confers multiple nucleoside reverse transcriptase inhibitor resistance.

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The article discusses the influence of external factors on the degree of risk of infection with flea allergic dermatitis among pets. Studied modern veterinary drugs that can be used to treat and prevent flea allergic dermatitis caused by flea lesions. Also, effective regimens for the treatment and prevention of flea allergic dermatitis have been drawn up. It was found that the preparation in the form of a collar is less effective than preparations in the form of "Spot-on". A flea collar is also less effective in dogs with thick coats. The drug in the form of "Spot-on" contact action begins to act after 12 hours, in contrast to the collar, which begins to act in full force after two days. The peculiarity of the form of release of the drug "Spot-on" allows it to evenly disperse on the skin of the animal and prevent a flea bite. This leads to rapid relief of itching and excludes new scratching. The tablet form does not fully protect against flea bites, which leads to a new outbreak of dietary supplements in the animal. The use of Spot-on drops in one of the group of subjects and the collar in the other group increased the effect of protection against flea bites and reduced the risk of developing dietary supplements in dogs. For cats, it is recommended to regularly treat fleas with the Spot-on contact action drug, the effectiveness of which has been proven by a decrease in the number of fleas in animals after the first day of treatment, in contrast to the form of release of the drug in the form of a collar. Droplet formulations in cats have also been shown to reduce itching and scratching.

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Antiretroviral therapy has markedly reduced morbidity and mortality for persons living with human immunodeficiency virus (HIV). Individual tailoring of antiretroviral regimens has the potential to further improve the long-term management of HIV through the mitigation of treatment failure and drug-induced toxicities. While the mechanisms underlying anti-HIV drug adverse outcomes are multifactorial, the application of drug-specific pharmacogenomic knowledge is required in order to move toward the personalization of HIV therapy. Thus, detailed understanding of the metabolism and transport of antiretrovirals and the influence of genetics on these pathways is important. To this end, this review provides an up-to-date overview of the metabolism of anti-HIV therapeutics and the impact of genetic variation in drug metabolism and transport on the treatment of HIV. Future perspectives on and current challenges in pursuing personalized HIV treatment are also discussed.