Prediction of Disease Progression and Clinical Response in Systemic Sclerosis: Experience From a Proof-of-Concept Trial.

OBJECTIVE: Using the modified Rodnan skin score (mRSS) as a surrogate for disease activity, a phase 2a study in patients with systemic sclerosis (SSc) measured efficacy of the autotaxin inhibitor ziritaxestat. Mathematical modeling of mRSS was used to predict disease progression, examine candidate trial designs, and predict the probability of successfully discriminating treatment effect. METHODS: Patients with SSc receiving 600 mg of ziritaxestat or placebo for 24 weeks were included, in addition to data up to week 52 of the open-label extension (OLE). Longitudinal mRSS data were described using a disease progression model; drug effect was a binary variable. Parameters used to predict the OLE mRSS outcome were estimated using data from the 24-week double-blind phase and validated with observed data. Three trial designs were simulated to identify which had the highest probability of detecting a treatment effect. Power to detect a treatment effect was quantified using the simulations. RESULTS: Maximum decreases from baseline in mRSS were 50.4% (ziritaxestat) and 34.7% (placebo). Study designs based on 300 patients randomized 2:1 or 1:1 to 600 mg of ziritaxestat or placebo had similar probabilities of detecting a significant treatment effect. Power to detect a treatment effect was >80% for all simulations. CONCLUSION: Disease progression and drug effect could be predicted beyond the range of observed data. This modeling and simulation approach may inform future trial design, including study duration, and predict the probability of success.

Population Pharmacokinetics of Sacituzumab Govitecan in Patients with Metastatic Triple-Negative Breast Cancer and Other Solid Tumors.

BACKGROUND AND OBJECTIVE: Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an antibody with affinity for Trop-2 coupled to SN-38 via hydrolyzable linker. SG is approved for patients with metastatic triple-negative breast cancer (mTNBC) who have received two or more prior chemotherapies (at least one in a metastatic setting) and for patients with pretreated hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer. METHODS: In these analyses, the pharmacokinetics of SG, free SN-38, and total antibody (tAB) were characterized using data from 529 patients with mTNBC or other solid tumors across two large clinical trials (NCT01631552; ASCENT, NCT02574455). Three population pharmacokinetic models were constructed using non-linear mixed-effects modeling; clinically relevant covariates were evaluated to assess their impact on exposure. Models for SG and tAB were developed independently whereas free SN-38 was sequentially generated via a first-order release process from SG. RESULTS: Pharmacokinetics of the three analytes were each described by a two-compartment model with estimated body weight-based scaling exponents for clearance and volume. Typical parameter estimates for clearance and steady-state volume of distribution were 0.133 L/h and 3.68 L for SG and 0.0164 L/h and 4.26 L for tAB, respectively. Mild-to-moderate renal impairment, mild hepatic impairment, age, sex, baseline albumin level, tumor type, UGT1A1 genotype, or Trop-2 expression did not have a clinically relevant impact on exposure for any of the three analytes. CONCLUSIONS: These analyses support the approved SG dosing regimen of 10 mg/kg as intravenous infusion on days 1 and 8 of 21-day cycles and did not identify a need for dose adjustment based on evaluated covariates or disease characteristics.

Dose Titration of Ixazomib Maintenance Therapy in Transplant-Ineligible Multiple Myeloma: Exposure-Response Analysis of the TOURMALINE-MM4 Study.

Ixazomib has been approved in several countries as single-agent maintenance therapy in newly diagnosed multiple myeloma, in both posttransplant and transplant-ineligible settings, based on two phase III studies. In these maintenance studies, patients were initially administered 3 mg ixazomib, escalating to 4 mg if the initial dose level was well tolerated through Cycles 1-4. Here, we report the results of exposure-response analyses of TOURMALINE-MM4, wherein relationships between exposure and clinical response, dose adjustments, and selected adverse events were evaluated. Similar progression-free survival benefits were observed across the range of ixazomib exposures achieved in the study. Moreover, increased ixazomib exposures corresponded to a higher probability of maintaining complete response. Exposure was not a significant predictor (P > 0.05) of hematological adverse events (anemia, neutropenia, thrombocytopenia) and peripheral neuropathy; however, higher exposures did correlate to increased probabilities of experiencing diarrhea, vomiting, nausea, rash, and fatigue. While ixazomib exposure was not predictive of dose reductions, lower apparent clearance values (corresponding to higher systemic exposures) were correlated with a reduced likelihood of escalating to the 4 mg dose. Thus, the dose titration approach balanced patient benefit and risk; it ensured that only patients for whom the 3 mg dose was safe/tolerable escalated to the higher dose, while maximizing the fraction of patients (85%) who were able to derive additional clinical benefit at 4 mg. Collectively, these results highlight the value of safety-driven personalized dosing to maximize patient benefit/risk.

Characterization and management of adverse events observed with mobocertinib (TAK-788) treatment for EGFR exon 20 insertion-positive non-small cell lung cancer.

BACKGROUND: Mobocertinib has demonstrated durable clinical benefit in platinum-pretreated patients (PPP) with epidermal growth factor receptor exon 20 insertion-positive non-small cell lung cancer (NSCLC). RESEARCH DESIGN AND METHODS: Pooled safety analysis of two studies included patients with NSCLC (N = 257) treated with the recommended phase 2 dose (RP2D) of mobocertinib (160 mg once daily). We report overall safety (treatment-emergent adverse events [TEAEs]) in the RP2D population; characterization of GI and skin-related events in 114 PPP from a phase 1/2 study (NCT02716116); and clinical activity in PPP with and without dose reductions due to TEAEs. RESULTS: In the RP2D population (N = 257), the most common TEAEs were diarrhea (93%), nausea (47%), rash (38%), and vomiting (37%). In PPP (N = 114), median times to diarrhea onset and resolution were 5 and 2 days, respectively. Median times to onset and resolution of skin-related events were 9 and 78 days, respectively. Among PPP with (n = 29) or without (n = 85) dose reductions due to TEAEs, overall response rates were 21% and 31% and median durations of response were 5.7 and 17.5 months, respectively. CONCLUSIONS: GI and skin-related events are common with mobocertinib; minimizing dose reductions with proactive management may improve clinical outcomes. TRIAL REGISTRATION: NCT02716116; NCT03807778.

Mobocertinib is a treatment for patients with a certain type of lung cancer. We analyzed the safety of mobocertinib in 257 patients with lung cancer. The most common side effects with mobocertinib were diarrhea, nausea, vomiting, and skin rash. In 114 patients with lung cancer who were treated in the past with chemotherapy that included platinum-based drugs, diarrhea started after about 5 days of mobocertinib treatment and went away in about 2 days. Skin-related side effects started after about 9 days and went away in about 2.5 months. One-fifth of patients who had to receive a smaller amount of mobocertinib because of side effects responded to treatment compared with one-third of patients who received the recommended mobocertinib amount. Managing side effects quickly can better help patients with lung cancer who are treated with mobocertinib.

Population pharmacokinetic/pharmacodynamic joint modeling of ixazomib efficacy and safety using data from the pivotal phase III TOURMALINE-MM1 study in multiple myeloma patients.

Ixazomib is an oral proteasome inhibitor approved in combination with lenalidomide and dexamethasone for the treatment of relapsed/refractory multiple myeloma (MM). Approval in the United States, Europe, and additional countries was based on results from the phase III TOURMALINE-MM1 (C16010) study. Here, joint population pharmacokinetic/pharmacodynamic time-to-event (TTE) and discrete time Markov models were developed to describe key safety (rash and diarrhea events, and platelet counts) and efficacy (myeloma protein [M-protein] and progression-free survival [PFS]) outcomes observed in TOURMALINE-MM1. Models reliably described observed safety and efficacy results; prior immunomodulatory drug therapy and race were significant covariates for diarrhea and rash events, respectively, whereas M-protein dynamics were sufficiently characterized using TTE models of relapse and dropout. Moreover, baseline M-protein was identified as a significant covariate for observed PFS. The developed framework represents an integrated approach to describing safety and efficacy with MM therapy, enabling the simulation of prospective trials and potential alternate dosing regimens.

Mobocertinib Dose Rationale in Patients with Metastatic NSCLC with EGFR Exon 20 Insertions: Exposure-Response Analyses of a Pivotal Phase I/II Study.

Mobocertinib is an oral tyrosine kinase inhibitor approved for treatment of patients with locally advanced or metastatic non-small cell lung cancer (mNSCLC) with epidermal growth factor receptor gene (EGFR) exon 20 insertion (ex20ins) mutations previously treated with platinum-based chemotherapy. These exposure-response analyses assessed potential relationships between exposure and efficacy or safety outcomes in platinum-pretreated patients with EGFRex20ins-positive mNSCLC who received mobocertinib 160 mg once daily (q.d.) in a pivotal phase I/II study. A statistically significant relationship between the independent review committee-assessed objective response rate and molar sum exposure to mobocertinib and its active metabolites (AP32960 and AP32914) was not discernable using a longitudinal model of clinical response driven by normalized dynamic molar sum exposure or a static model of best clinical response based on time-averaged molar sum exposure. However, the longitudinal model suggested a trend for decreased probability of response with the change in mobocertinib molar sum exposure between the 160- and 120-mg doses (odds ratio: 0.78; 95% confidence interval: 0.55-1.10; P = 0.156). Time-averaged molar sum exposure was a significant predictor of the rate of grade ≥ 3 treatment-emergent adverse events (AEs). Taken together, these exposure-efficacy and exposure-safety results support a favorable benefit-risk profile for the approved mobocertinib 160-mg q.d. dose and dose modification guidelines for patients experiencing AEs.

Population pharmacokinetics of mobocertinib in healthy volunteers and patients with non-small cell lung cancer.

Mobocertinib is an oral tyrosine kinase inhibitor approved for treatment of patients with locally advanced or metastatic non-small cell lung cancer (mNSCLC) with epidermal growth factor receptor gene (EGFR) exon 20 insertion mutations whose disease has progressed on or after platinum-based chemotherapy. This population pharmacokinetic (PK) analysis describes the PK of mobocertinib and its active metabolites, AP32960, and AP32914, using data from two phase I studies in healthy volunteers (n = 110) and two phase I/II studies in patients with mNSCLC (n = 317), including the pivotal phase I/II study. The plasma PK of mobocertinib, AP32960, and AP32914 were well-characterized by a joint semimechanistic model that included two compartments for mobocertinib with absorption via three transit compartments, two compartments for AP32960, and one compartment for AP32914. The observed time-dependency in PK was described by an enzyme compartment with drug and metabolite concentration-dependent stimulation of enzyme production, resulting in the enzyme increasing the apparent clearance of mobocertinib, AP32960, and AP32914. Effects of healthy volunteer status (vs. patients with mNSCLC) on apparent oral clearance of all three moieties and on apparent central volume of distribution for mobocertinib were included as structural covariates in the final model. No clinically meaningful differences in mobocertinib PK were observed based on age (18-86 years), race, sex, body weight (37.3-132 kg), mild-to-moderate renal impairment (estimated glomerular filtration rate 30-89 ml/min/1.73 m2 by modification of diet in renal disease equation), or mild-to-moderate hepatic impairment, suggesting that no dose adjustment is required based on these covariates in patients with mNSCLC.

Population Pharmacokinetics of Ponatinib in Healthy Adult Volunteers and Patients With Hematologic Malignancies and Model-Informed Dose Selection for Pediatric Development.

The BCR-ABL1 inhibitor ponatinib is approved for the treatment of adults with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia, including those with the T315I mutation. We report a population pharmacokinetic model-based analysis for ponatinib and its application to inform dose selection for pediatric development. Plasma concentration-time data were collected from 260 participants (86 healthy volunteers; 174 patients with hematologic malignancies) enrolled across 7 clinical trials. Data were analyzed using nonlinear mixed-effects modeling. Ponatinib pharmacokinetics were described by a 2-compartment model with first-order elimination from the central compartment. The final model included body weight and age as covariates on the apparent central volume of distribution; however, exposure variability explained by these covariates was small compared with overall variability in the population. None of the covariates evaluated, including sex, age (19-85 years), race, body weight (40.7-152.0 kg), total bilirubin (0.1-3.16 mg/dL), alanine aminotransferase (6-188 U/L), albumin (23.0-52.5 g/L), and creatinine clearance (≥28 mL/min) had clinically meaningful effects on apparent oral clearance. Simulations based on the final model predicted that daily doses of 15 to 45 mg result in steady-state average concentrations that are in the pharmacological range for BCR-ABL1 inhibition and approximate or exceed concentrations associated with suppression of T315I mutant clones. The final model was adapted using allometric scaling to inform dose selection for pediatric development. Clinicaltrials.gov identifier: NCT00660920; NCT01667133; NCT01650805.

Brigatinib Dose Rationale in Anaplastic Lymphoma Kinase-Positive Non-Small Cell Lung Cancer: Exposure-Response Analyses of Pivotal ALTA Study.

Brigatinib is a kinase inhibitor indicated for patients with advanced anaplastic lymphoma kinase-positive non-small cell lung cancer who progressed on or are intolerant to crizotinib. Approval was based on results from a randomized, dose-ranging phase II study (ALK in Lung Cancer Trial of AP26113 (ALTA)). Despite an apparent dose-response relationship for efficacy in ALTA, an exposure-response relationship was not discernable using static models driven by time-averaged exposure. However, exposure-response modeling using daily time-varying area under the concentration curve as the predictor in time-to-event models predicted that increasing the dose of brigatinib (range, 30 mg once daily (q.d.) to 240 mg q.d.) would result in clinically meaningful improvements in progression-free survival (PFS), intracranial PFS, and overall survival. Grade ≥ 2 rash and amylase elevation were predicted to significantly increase with brigatinib exposure. These results provided support for a favorable benefit-risk profile with the approved dosing regimen (180 mg q.d. with 7-day lead-in at 90 mg) versus 90 mg q.d.

Meta-Analyses of Clinical Efficacy of Risankizumab and Adalimumab in Chronic Plaque Psoriasis: Supporting Evidence of Risankizumab Superiority.

Risankizumab, an anti-interleukin-23 monoclonal antibody, achieved significantly (P < 0.001) greater Psoriasis Area and Severity Index (PASI) and static Physician Global Assessment (sPGA) clear or almost clear (0/1) responses than adalimumab in a phase III trial in patients with moderate-to-severe psoriasis. Meta-analyses of the PASI 50, PASI 75, PASI 90, PASI 100, and sPGA0/1 responses after 16 weeks of treatment from eight (three for risankizumab and five for adalimumab) randomized, placebo-controlled trials were conducted to estimate the efficacy difference between risankizumab and adalimumab. For PASI 75, PASI 90, PASI 100, and sPGA0/1 responses, the estimated effect differences (95% confidence interval) between risankizumab and adalimumab were 15.2% (10.1%, 20.4%), 23.7% (15.7%, 31.2%), 20.8% (13.0%, 28.7%), and 20.1% (13.7%, 26.1%), respectively. These results were consistent with the observed efficacy difference from the head-to-head phase III trial, which was not included in the meta-analyses, providing independent, confirmatory evidence of the superior efficacy of risankizumab compared with adalimumab for treatment of moderate-to-severe psoriasis.

Operating characteristics of stepwise covariate selection in pharmacometric modeling.

Stepwise covariate modeling (SCM) is a widely used tool in pharmacometric analyses to identify covariates that explain between-subject variability (BSV) in exposure and exposure-response relationships. However, this approach has several potential weaknesses, including over-estimated covariate effect and incorrect selection of covariates due to collinearity. In this work, we investigated the operating characteristics (i.e., accuracy, precision, and power) of SCM in a controlled setting by simulating sixteen scenarios with up to four covariate relationships. The SCM analysis showed a decrease in the power to detect the true covariates as model complexity increased. Furthermore, false highly correlated covariates were frequently selected in place of or in addition to the true covariates. Relative root mean square errors (RMRSE) ranged from 1 to 51% for the fixed effects parameters, increased with the number of covariates included in the model, and were slightly higher than the RMRSE obtained with a simple re-estimation exercise with the true model (i.e., stochastic simulation and estimation). RMRSE for BSV increased with the number of covariates included in the model, with a covariance parameter RMRSE of almost 135% in the most complex scenario. Loose boundary conditions on the continuous covariate power relation appeared to have an impact on the covariate model selection in SCM. A stricter boundary condition helped achieve high power (> 90%), even in the most complex scenario. Finally, reducing the sample size in terms of number of subjects or number of samples proved to have an impact on the power to detect the correct model.

Model-Informed Drug Development for Ixazomib, an Oral Proteasome Inhibitor.

Model-informed drug development (MIDD) was central to the development of the oral proteasome inhibitor ixazomib, facilitating internal decisions (switch from body surface area (BSA)-based to fixed dosing, inclusive phase III trials, portfolio prioritization of ixazomib-based combinations, phase III dose for maintenance treatment), regulatory review (model-informed QT analysis, benefit-risk of 4 mg dose), and product labeling (absolute bioavailability and intrinsic/extrinsic factors). This review discusses the impact of MIDD in enabling patient-centric therapeutic optimization during the development of ixazomib.

Population Pharmacokinetic Analysis of Ixazomib, an Oral Proteasome Inhibitor, Including Data from the Phase III TOURMALINE-MM1 Study to Inform Labelling.

Ixazomib is an oral proteasome inhibitor, approved in USA, Canada, Australia and Europe in combination with lenalidomide and dexamethasone, for the treatment of patients with multiple myeloma who have received at least one prior therapy. We report a population pharmacokinetic model-based analysis for ixazomib that was pivotal in describing the clinical pharmacokinetics of ixazomib, to inform product labelling. Plasma concentration-time data were collected from 755 patients who received oral or intravenous ixazomib in once- or twice-weekly schedules in ten trials, including the global phase III TOURMALINE-MM1 study. Data were analysed using nonlinear mixed-effects modelling (NONMEM software version 7.2, ICON Development Solutions, Hanover, MD, USA). Ixazomib plasma concentrations from intravenous and oral studies were described by a three-compartment model with linear distribution and elimination kinetics, including first-order linear absorption with a lag time describing the oral dose data. Body surface area on the volume of the second peripheral compartment was the only covariate included in the final model. None of the additional covariates tested including body surface area (1.2-2.7 m2), sex, age (23-91 years), race, mild/moderate renal impairment and mild hepatic impairment were found to impact systemic clearance, suggesting that no dose adjustment is required based on these covariates. The geometric mean terminal disposition phase half-life was 9.5 days, steady-state volume of distribution was 543 L and systemic clearance was 1.86 L/h. The absolute bioavailability of an oral dose was estimated to be 58%.

Modelling the electrical activity of pancreatic alpha-cells based on experimental data from intact mouse islets.

Detailed experimental data from patch clamp experiments on pancreatic alpha-cells in intact mouse islets are used to model the electrical activity associated with glucagon secretion. Our model incorporates L- and T-type Ca(2+) currents, delayed rectifying and A-type K(+) currents, a voltage-gated Na(+) current, a KATP conductance, and an unspecific leak current. Tolbutamide closes KATP channels in the alpha-cell, leading to a reduction of the resting conductance from 1.1 nS to 0.4 nS. This causes the alpha-cell to depolarise from -76 mV to 33 mV. When the basal membrane potential passes the range between -60 and -35 mV, the alpha-cell generates action potentials. At higher voltages, the alpha-cell enters a stable depolarised state and the electrical activity ceases. The effects of tolbutamide are simulated by gradually reducing the KATP conductance (g(K,ATP)) from 500 pS to 0 pS. When g(K,ATP ) is between 72 nS and 303 nS, the model generates action potentials in the same voltage range as the alpha-cell. When g(K,ATP) is lower than 72 nS, the model enters a stable depolarised state, and firing of action potentials is inhibited due to voltage-dependent inactivation of the Na(+) and T-type Ca(2+) currents. This is in accordance with experimental results. Changing the inactivation parameters to those observed in somatostatin-secreting delta-cells abolishes the depolarised inactive state, and leads to beta-cell like electrical activity with action potentials generated even after complete closure of the KATP channels.