| 1. |
- Clewe, Oskar, et al.
(författare)
-
A model-based analysis identifies differences in phenotypic resistance between in vitro and in vivo : implications for translational medicine within tuberculosis.
- 2020
-
Ingår i: Journal of Pharmacokinetics and Pharmacodynamics. - : Springer Science and Business Media LLC. - 1567-567X .- 1573-8744. ; 47:5, s. 421-430
-
Tidskriftsartikel (refereegranskat)abstract
- Proper characterization of drug effects on Mycobacterium tuberculosis relies on the characterization of phenotypically resistant bacteria to correctly establish exposure-response relationships. The aim of this work was to evaluate the potential difference in phenotypic resistance in in vitro compared to murine in vivo models using CFU data alone or CFU together with most probable number (MPN) data following resuscitation with culture supernatant. Predictions of in vitro and in vivo phenotypic resistance i.e. persisters, using the Multistate Tuberculosis Pharmacometric (MTP) model framework was evaluated based on bacterial cultures grown with and without drug exposure using CFU alone or CFU plus MPN data. Phenotypic resistance and total bacterial number in in vitro natural growth observations, i.e. without drug, was well predicted by the MTP model using only CFU data. Capturing the murine in vivo total bacterial number and persisters during natural growth did however require re-estimation of model parameter using both the CFU and MPN observations implying that the ratio of persisters to total bacterial burden is different in vitro compared to murine in vivo. The evaluation of the in vitro rifampicin drug effect revealed that higher resolution in the persister drug effect was seen using CFU and MPN compared to CFU alone although drug effects on the other bacterial populations were well predicted using only CFU data. The ratio of persistent bacteria to total bacteria was predicted to be different between in vitro and murine in vivo. This difference could have implications for subsequent translational efforts in tuberculosis drug development.
|
|
| 2. |
- De Jager, Veronique, et al.
(författare)
-
Early Bactericidal Activity of Meropenem plus Clavulanate (with or without Rifampin) for Tuberculosis : The COMRADE Randomized, Phase 2A Clinical Trial
- 2022
-
Ingår i: American Journal of Respiratory and Critical Care Medicine. - : American Thoracic Society. - 1073-449X .- 1535-4970. ; 205:10, s. 1228-1235
-
Tidskriftsartikel (refereegranskat)abstract
- Rationale: Carbapenems are recommended for treatment of drug-resistant tuberculosis. Optimal dosing remains uncertain.Objectives: To evaluate the 14-day bactericidal activity of meropenem, at different doses, with or without rifampin.Methods: Individuals with drug-sensitive pulmonary tuberculosis were randomized to one of four intravenous meropenem-based arms: 2 g every 8 hours (TID) (arm C), 2 g TID plus rifampin at 20 mg/kg once daily (arm D), 1 g TID (arm E), or 3 g once daily (arm F). All participants received amoxicillin/clavulanate with each meropenem dose. Serial overnight sputum samples were collected from baseline and throughout treatment. Median daily fall in colony-forming unit (CFU) counts per milliliter of sputum (solid culture) (EBA(CFU0-14)) and increase in time to positive culture (TTP) in liquid media were estimated with mixed-effects modeling. Serial blood samples were collected for pharmacokinetic analysis on Day 13.Measurements and Main Results: Sixty participants enrolled. Median EBA(CFU0-14) counts (2.5th-97.5th percentiles) were 0.22 (0.12-0.33), 0.12 (0.057-0.21), 0.059 (0.033-0.097), and 0.053 (0.035-0.081); TTP increased by 0.34 (0.21-0.75), 0.11 (0.052-037), 0.094 (0.034-0.23), and 0.12 (0.04-0.41) (log(10) h), for arms C-F, respectively. Meropenem pharmacokinetics were not affected by rifampin coadministration. Twelve participants withdrew early, many of whom cited gastrointestinal adverse events.Conclusions: Bactericidal activity was greater with the World Health Organization-recommended total daily dose of 6 g daily than with a lower dose of 3 g daily. This difference was only detectable with solid culture. Tolerability of intravenous meropenem, with amoxicillin/clavulanate, though, was poor at all doses, calling into question the utility of this drug in second-line regimens.
|
|
| 3. |
- Faraj, Alan, et al.
(författare)
-
Difference in persistent tuberculosis bacteria between in vitro and sputum from patients : implications for translational predictions
- 2020
-
Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate the number of persistent bacteria in sputum from tuberculosis patients compared to in vitro and to suggest a model-based approach for accounting for the potential difference. Sputum smear positive patients (n=25) provided sputum samples prior to onset of chemotherapy. The number of cells detected by conventional agar colony forming unit (CFU) and most probable number (MPN) with Rpf supplementation were quantified. Persistent bacteria was assumed to be the difference between MPNrpf and CFU. The difference in persistent bacteria between in vitro and human sputum prior to chemotherapy was quantified using different model-based approaches. The persistent bacteria in sputum was 17% of the in vitro levels, suggesting a difference in phenotypic resistance, whereas no difference was found for multiplying bacterial subpopulations. Clinical trial simulations showed that the predicted time to 2 log fall in MPNrpf in a Phase 2a setting using in vitro pre-clinical efficacy information, would be almost 3 days longer if drug response was predicted ignoring the difference in phenotypic resistance. The discovered phenotypic differences between in vitro and humans prior to chemotherapy could have implications on translational efforts but can be accounted for using a model-based approach for translating in vitro to human drug response.
|
|
| 4. |
- Faraj, Alan, et al.
(författare)
-
Drug effect of clofazimine on persisters explain an unexpected increase in bacterial load from patients
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Tuberculosis (TB) drug development is dependent on informative trials to secure development of new antibiotics and combination regimens. Clofazimine (CFZ) and pyrazinamid (PZA) are important components of recommended standard multi-drug treatments of TB. Paradoxically, in a Phase IIa trial aiming to define the early bactericidal activity (EBA) of CFZ and PZA monotherapy over the first 14 days of treatment, no significant drug effect was demonstrated for the two drugs using traditional statistical analysis. Using a model-based analysis we characterized statistically significant exposure-response relationships for both drugs that could explain the original findings of increase in colony forming units (CFU) with CFZ treatment and no effect with PZA. Sensitive analyses are crucial for exploring drug effects in early clinical trials to make right decisions for advancement to further development. We propose that this quantitative semi-mechanistic approach provides a rational framework for analysing Phase IIa EBA studies, and can accelerate anti-TB drug development.
|
|
| 5. |
- Faraj, Alan, et al.
(författare)
-
Drug Effect of Clofazimine on Persisters Explains an Unexpected Increase in Bacterial Load in Patients
- 2020
-
Ingår i: Antimicrobial Agents and Chemotherapy. - : AMER SOC MICROBIOLOGY. - 0066-4804 .- 1098-6596. ; 64:5
-
Tidskriftsartikel (refereegranskat)abstract
- Antituberculosis (anti-TB) drug development is dependent on informative trials to secure the development of new antibiotics and combination regimens. Clofazimine (CLO) and pyrazinamide (PZA) are important components of recommended standard multidrug treatments of TB. Paradoxically, in a phase IIa trial aiming to define the early bactericidal activity (EBA) of CLO and PZA monotherapy over the first 14 days of treatment, no significant drug effect was demonstrated for the two drugs using traditional statistical analysis. Using a model-based analysis, we characterized the statistically significant exposure-response relationships for both drugs that could explain the original findings of an increase in the numbers of CFU with CLO treatment and no effect with PZA. Sensitive analyses are crucial for exploring drug effects in early clinical trials to make the right decisions for advancement to further development. We propose that this quantitative semimechanistic approach provides a rational framework for analyzing phase IIa EBA studies and can accelerate anti-TB drug development.
|
|
| 6. |
- Faraj, Alan, et al.
(författare)
-
Model-based approaches to prospectively power pediatric pharmacokinetic trials with limited sample size
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Rare disease studies in pediatric subjects are challenging due to small sample sizes. Pharmacokinetic (PK) information in pediatric subjects is important and often used for matching strategy towards adults informing pediatric development program. Prior to studying PK in children, it is important to optimize the sparse sampling schedule and show that the study is designed to estimate key PK parameters with sufficient certainty. In this work, the sampling schedule in children was optimized for marzeptacog alfa activated (MarzAA) and dalcinonacog alfa (DalcA), two drugs in development for treatment of hemophilia. Subsequently, evaluation of different model-based approaches to calculate the power to estimate clearance (CL) and volume of distribution (V) using a fixed sample size (n=24) was performed. Usage of Bayesian priors (up to 2x inflation of the adult priors) performed well (power 80 %), but with lower power with decreasing informativeness (5x and 10x inflation of the adult priors), in particular for DalcA. Reusing the full adult model or a simplified model for standalone analysis of the pediatric data did not perform well (<80% power). Fixing the adult PK parameters except for CL and V performed well when pooling adult and pediatric data (power 100 %). In general, the power to estimate V alone or CL together with V was lower than for CL, indicating that the sampling schedules were more informative for CL. Although Bayesian prior approaches were shown to perform well without need of pooling data, other approaches that require less technical expertise and no need for simplification of the adult model were found to be good alternatives when pooling of data is possible.
|
|
| 7. |
- Faraj, Alan, et al.
(författare)
-
Model-informed pediatric dose selection of marzeptacog alfa (activated) : An exposure matching strategy
- 2023
-
Ingår i: CPT. - : John Wiley & Sons. - 2163-8306. ; 12:7, s. 977-987
-
Tidskriftsartikel (refereegranskat)abstract
- Marzeptacog alfa (activated) (MarzAA) is an activated recombinant human rFVII variant intended for subcutaneous (s.c.) administration to treat or prevent bleeding in individuals with hemophilia A (HA) or B (HB) with inhibitors, and other rare bleeding disorders. The s.c. administration provides benefits over i.v. injections. The objective of the study was to support the first-in-pediatric dose selection for s.c. MarzAA to treat episodic bleeding episodes in children up through 11 years in a registrational phase III trial. Assuming the same exposure-response relationship as in adults, an exposure matching strategy was used with a population pharmacokinetics model. A sensitivity analysis evaluating the impact of doubling in absorption rate and age-dependent allometric exponents on dose selection was performed. Subsequently, the probability of trial success, defined as the number of successful trials for a given pediatric dose divided by the number of simulated trials (n = 1000) was studied. A successful trial was defined as outcome where four, three, or two out of 24 pediatric subjects per trial were allowed to fall outside the adult exposures after s.c. administration of 60 mu g/kg. A dose of 60 mu g/ kg in children with HA/HB was supported by the clinical trial simulations to match exposures in adults. The sensitivity analyses further supported selection of the 60 mu g/kg dose level in all age groups. Moreover, the probability of trial success evaluations given a plausible design confirmed the potential of a 60 mu g/kg dose level. Taken together, this work demonstrates the utility of model-informed drug development and could be helpful for other pediatric development programs for rare diseases.
|
|
| 8. |
- Faraj, Alan, et al.
(författare)
-
Model-Informed Support of Dose Selection for Prophylactic Treatment with Dalcinonacog Alfa in Adult and Paediatric Hemophilia B Patients
- 2023
-
Ingår i: Advances in Therapy. - : Springer Nature. - 0741-238X .- 1865-8652. ; 40:9, s. 3739-3750
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionDalcinonacog alfa (DalcA), a novel subcutaneously administered recombinant human factor IX (FIX) variant is being developed for adult and paediatric patients with hemophilia B (HB). DalcA has been shown to raise FIX to clinically meaningful levels in adults with HB. This work aimed to support dosing regimen selection in adults and perform first-in-paediatric dose extrapolations using a model-based pharmacokinetic (PK) approach.MethodsA population PK model was built using adult data from two clinical trials (NCT03186677, NCT03995784). With allometry in the model, clinical trial simulations were performed to study alternative dosing regimens in adults and children. Steady-state trough levels and the time-to-reach target were derived to inform dose selection.ResultsAlmost 90% of the adults were predicted to achieve desirable FIX levels, i.e. 10% FIX activity, following daily 100 IU/kg dosing, with 90% of the subjects reaching target within 1.6-7.1 days. No every-other-day regimen met the target. A dose of 125 IU/kg resulted in adequate FIX levels down to 6 years, whereas a 150 IU/kg dose was needed below 6 down to 2 years of age. For subjects down to 6 years that did not reach target with 125 IU/kg, a dose escalation to 150 IU/kg was appropriate. The children below 6 to 2 years were shown to need a dose escalation to 200 IU/kg if 150 IU/kg given daily was insufficient.ConclusionThis study supported the adult dose selection for DalcA in the presence of sparse data and enabled first-in-paediatric dose selection to achieve FIX levels that reduce risk of spontaneous bleeds.
|
|
| 9. |
- Faraj, Alan
(författare)
-
Pharmacometric models to inform dose selection and study design : Applied in hemophilia and tuberculosis
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- While tuberculosis is a global pandemic, hemophilia is a rare disease which many have not heard of. Due to tuberculosis mainly being a problem in developing countries and hemophilia being a rare disease, they are not as heard of as other diseases such as cancer or metabolic diseases which are on the rise in Western societies. The quality of life for patients suffering from these diseases is notably impaired and novel drugs are warranted to further improve the treatment and management of both diseases. As market incentives are a limiting factor, it is important that the efforts that are taken to develop novel drugs are carried out in an informative manner. One strategy to incorporate as much information as possible to inform decision making in drug development is to use pharmacometric methods. Such strategies enable simultaneous analysis of different types of data that are generated during drug development programs. In this thesis, the aim was to develop and apply pharmacometric models to facilitate dose selection and study designs in clinical programs that aim at developing new drugs for tuberculosis and hemophilia. A standardized analysis approach of early clinical trials studying drugs against tuberculosis was presented including power calculations that showed the number of patients needed to detect drug effects. Such efforts are important as showing drug effect in early trials will aid decision making into significantly longer and costlier late trials. The approach was used to analyze a clinical trial studying if the current dose of meropenem can be lowered without negatively impacting drug effects and improving the already poor tolerability of the drug. The study found that lowering the dose may lower activity without any improvement of the tolerability properties. Furthermore, population pharmacokinetic models were developed for two novel hemostatic drugs in development for prophylactic and on-demand treatment of hemophilia. Based on the models, clinical trials in adult and pediatric subjects were supported. One of the trials were performed and it was showed with a model-based analysis that the new drug which is given subcutanously has similar efficacy as current intravenously given standard of care alternatives. Using the developed models, different strategies for designing pharmacokinetic trials in children was also presented. In conclusion, the work performed within this thesis has contributed to the development of new drugs against tuberculosis and hemophilia.
|
|
| 10. |
- Faraj, Alan, et al.
(författare)
-
Phase III dose selection of marzeptacog alfa (activated) informed by population pharmacokinetic modeling : A novel hemostatic drug
- 2022
-
Ingår i: CPT. - : John Wiley & Sons. - 2163-8306. ; 11:12, s. 1628-1637
-
Tidskriftsartikel (refereegranskat)abstract
- Marzeptacog alfa (activated) (MarzAA) is an activated recombinant human FVII (rFVIIa) variant developed as subcutaneous (s.c.) administration for the treatment or prevention of bleeding episodes in patients with hemophilia A (HA) or hemophilia B (HB) with inhibitors and other rare bleeding disorders. Population pharmacokinetic (PK) modeling was applied for dose selection for a pivotal phase III clinical trial evaluating s.c. MarzAA for episodic treatment of spontaneous or traumatic bleeding episodes. The population PK model used MarzAA intravenous and s.c. data from previously completed clinical trials in patients with HA/HB with or without inhibitors. Based on the model, clinical trial simulations were performed to predict MarzAA exposure after different dosing regimens. The exposure target was identified using an exposure-matching strategy with a wild-type rFVIIa but adjusting for the difference in potency between the two compounds. Simulations demonstrated a sufficient absorption rate and prolonged exposure following a single 60 μg/kg dose leading to 51% and 70% of the population reaching levels above the target after 3 and 6 h, respectively. According to the phase III protocol, if a second dose was required after 3 h because of a lack of efficacy, 90% of the population was observed to be above target 6 h after the initial dose. The model-informed drug development approach integrated information from several trials and guided dose selection in the pivotal phase III clinical trial for episodic treatment of an acute bleeding event in individuals with HA or HB with inhibitors without the execution of a phase II trial for that indication.
|
|
| 11. |
- Faraj, Alan, et al.
(författare)
-
Subcutaneous Marzeptacog Alfa (Activated) for On‐Demand Treatment of Bleeding Events in Subjects With Hemophilia A or B With Inhibitors
- 2024
-
Ingår i: Clinical Pharmacology and Therapeutics. - : John Wiley & Sons. - 0009-9236 .- 1532-6535. ; 115:3, s. 498-505
-
Tidskriftsartikel (refereegranskat)abstract
- Marzeptacog alfa (MarzAA) is under development for subcutaneous treatment of episodic bleeds in patients with hemophilia A/B and was studied in a phase III trial evaluating MarzAA compared with standard-of-care (SoC) for on-demand use. The work presented here aimed to evaluate MarzAA and SoC treatment of bleeding events on a standardized four-point efficacy scale (poor, fair, good, and excellent). Two continuous-time Markov modeling approaches were explored; a four-state model analyzing all four categories of bleeding improvement and a two-state model analyzing a binarized outcome (treatment failure (poor/fair), and treatment success (good/excellent)). Different covariates impacting improvement of bleeding episodes as well as a putative relationship between MarzAA exposure and improvement of bleeding episodes were evaluated. In the final four-state model, higher baseline diastolic blood pressure and higher age (> 33 years of age) were found to negatively and positively impact improvement of bleeding condition, respectively. Bleeding events occurring in knees and ankles were found to improve faster than bleeding events at other locations. The covariate effects had most impact on early treatment success (≤ 3 hours) whereas at later timepoints (> 12 hours), treatment success was similar for all patients indicating that these covariates might be clinically relevant for early treatment response. A statistically significant relationship between MarzAA zero-order absorption and improvement of bleedings (P < 0.05) were identified albeit with low precision. No statistically significant difference in treatment response between MarzAA and intravenous SoC was identified, indicating the potential of MarzAA for treatment of episodic bleeding events with a favorable subcutaneous administration route.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Mockeliunas, Laurynas, et al.
(författare)
-
Standards for model-based early bactericidal activity analysis and sample size determination in tuberculosis drug development
- 2023
-
Ingår i: Frontiers in Pharmacology. - : Frontiers Media S.A.. - 1663-9812. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Background: A critical step in tuberculosis (TB) drug development is the Phase 2a early bactericidal activity (EBA) study which informs if a new drug or treatment has short-term activity in humans. The aim of this work was to present a standardized pharmacometric model-based early bactericidal activity analysis workflow and determine sample sizes needed to detect early bactericidal activity or a difference between treatment arms.Methods: Seven different steps were identified and developed for a standardized pharmacometric model-based early bactericidal activity analysis approach. Non-linear mixed effects modeling was applied and different scenarios were explored for the sample size calculations. The sample sizes needed to detect early bactericidal activity given different TTP slopes and associated variability was assessed. In addition, the sample sizes needed to detect effect differences between two treatments given the impact of different TTP slopes, variability in TTP slope and effect differences were evaluated.Results: The presented early bactericidal activity analysis approach incorporates estimate of early bactericidal activity with uncertainty through the model-based estimate of TTP slope, variability in TTP slope, impact of covariates and pharmacokinetics on drug efficacy. Further it allows for treatment comparison or dose optimization in Phase 2a. To detect early bactericidal activity with 80% power and at a 5% significance level, 13 and 8 participants/arm were required for a treatment with a TTP-EBA(0-14) as low as 11 h when accounting for variability in pharmacokinetics and when variability in TTP slope was 104% [coefficient of variation (CV)] and 22%, respectively. Higher sample sizes are required for smaller early bactericidal activity and when pharmacokinetics is not accounted for. Based on sample size determinations to detect a difference between two groups, TTP slope, variability in TTP slope and effect difference between two treatment arms needs to be considered.Conclusion: In conclusion, a robust standardized pharmacometric model-based EBA analysis approach was established in close collaboration between microbiologists, clinicians and pharmacometricians. The work illustrates the importance of accounting for covariates and drug exposure in EBA analysis in order to increase the power of detecting early bactericidal activity for a single treatment arm as well as differences in EBA between treatments arms in Phase 2a trials of TB drug development.
|
|
