Clinical pharmacology strategies to accelerate the development of polatuzumab vedotin and summary of key findings

The favorable benefit-risk profile of polatuzumab vedotin, as demonstrated in a pivotal Phase Ib/II randomized study (GO29365; NCT02257567), coupled with the need for effective therapies in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), prompted the need to accelerate polatuzumab vedotin development. An integrated, fit-for-purpose clinical pharmacology package was designed to support regulatory approval. To address key clinical pharmacology questions without dedicated clinical pharmacology studies, we leveraged non-clinical and clinical data for polatuzumab vedotin, published clinical data for brentuximab vedotin, a similar antibody-drug conjugate, and physiologically based pharmacokinetic and population pharmacokinetic modeling approaches. We review strategies and model-informed outcomes that contributed to regulatory approval of polatuzumab vedotin plus bendamustine and rituximab in R/R DLBCL. These strategies made polatuzumab vedotin available to patients earlier than previously possible; depending on the strength of available data and the regulatory/competitive environment, they may also prove useful in accelerating the development of other agents.

Bioavailability Evaluation of Venetoclax Lower-Strength Tablets and Oral Powder Formulations to Establish Interchangeability with the 100 mg Tablet

Background and Objective

Venetoclax is an approved BCL-2 inhibitor, currently under evaluation in different hematological malignancies in adult and pediatric populations. Venetoclax is available as 10, 50, and 100 mg tablets. To provide an alternative to patients who find taking the commonly prescribed 100 mg tablet a challenge, the interchangeability of lower-strength tablets with the 100 mg tablet was investigated. Additionally, newly developed oral suspension powder formulations to facilitate dosing in pediatrics were evaluated.

Methods

Pharmacokinetic data from 80 healthy female participants from three phase I studies were utilized to evaluate the bioavailability of (1) 10 and 50 mg tablets relative to a 100 mg tablet; (2) 0.72 and 7.2% (drug to total weight) oral powder formulations relative to the 100 mg tablet; and (3) oral powder formulations administered using different vehicles (apple juice, apple sauce, and yogurt) relative to water under fed conditions.

Results

Bioavailability assessments at a 100 mg dose of venetoclax demonstrated bioequivalence across the 10, 50, and 100 mg tablet strengths. Oral powder formulations met the bioequivalence criteria (0.80–1.25) with respect to area under the concentration–time curve to time of the last measurable concentration (AUC_t) and to infinite time (AUC_∞) but exhibited a slightly lower maximum plasma concentration (C_max). Exposure–response analyses were utilized to demonstrate that the lower C_max observed with the powder formulations is not clinically meaningful. The delivery vehicles tested did not affect the bioavailability of venetoclax oral powder formulations.

Conclusions

The smaller-sized tablets (10 and 50 mg) and the newly developed oral powder formulations of venetoclax can be used interchangeably with the 100 mg tablets to improve the patients’ experience, while maintaining adequate exposure.

Clinical Trials Identifiers

NCT01682616, 11 September 2012; NCT02005471, 9 December 2013; NCT02242942, 17 September 2014; NCT02203773, 30 July 2014; NCT02287233, 10 November 2014; NCT02993523, 15 December 2016; NCT03069352, 3 March 2017.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-022-01172-4.

Pharmacokinetics and Exposure-Response Analysis of Venetoclax + Obinutuzumab in Chronic Lymphocytic Leukemia: Phase 1b Study and Phase 3 CLL14 Trial

INTRODUCTION

This study aims to investigate pharmacokinetics (PK) and exposure-response parameters of the 400 mg once-daily venetoclax dose regimen in combination with obinutuzumab, which was approved for the first-line (1L) treatment of chronic lymphocytic leukemia (CLL) based on data from the phase 3 CLL14 study and the phase 1b dose-finding GP28331 study.

METHODS

Parameter estimates and uncertainty, which were estimated by a previously developed population PK (popPK) model, were used as informative priors for this analysis. They were re-estimated, and then used to evaluate additional covariate effects, describe venetoclax PK when administered with obinutuzumab, and provide empirical Bayes estimates of PK parameters and exposure. Exposure-progression-free survival (PFS) and exposure-safety relationships were assessed using data from CLL14, with steady-state nominal venetoclax exposure (C_{meanSS,nominal}) as the predictor variable. Exposure-safety analyses were conducted using logistic regression for selected treatment-emergent grade ≥ 3 adverse events (AEs) and serious AEs (SAEs). Dose intensities were summarized by tertiles of C_{meanSS,nominal}.

RESULTS

PK data from 274 patients (CLL14, n = 194; GP28331, n = 80) were included. The final model provided good fit of the observed data. Obinutuzumab co-administration, history of prior treatments, and disease severity at baseline had no appreciable influence on venetoclax steady-state exposure. No significant correlations were observed between venetoclax exposure and PFS, or between venetoclax exposure and the probability of treatment-emergent grade ≥ 3 neutropenia, grade ≥ 3 thrombocytopenia, grade ≥ 3 infections, and SAEs. Median dose intensities for venetoclax and obinutuzumab remained similar across venetoclax exposure tertiles.

CONCLUSION

PopPK and exposure-efficacy, exposure-safety, and exposure-tolerability analyses support the 400 mg once-daily venetoclax dose plus obinutuzumab for 1L treatment in patients with CLL.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifiers NCT02242942 and NCT02339181.

CAMMA 3: A multicenter phase Ib trial evaluating the safety, pharmacokinetics, and activity of subcutaneous cevostamab monotherapy in patients with relapsed or refractory multiple myeloma

TPS8070

Background: Multiple myeloma (MM) remains an incurable disease. Although new treatment paradigms have increased survival, most patients relapse and treatment in later lines remains a challenge. Prognosis for patients refractory to immunomodulatory drugs, proteasome inhibitors and anti-CD38 antibodies is extremely poor, with an estimated survival of < 1 year (Gandhi et al. 2019). Therefore, patients with relapsed/refractory (R/R) disease represent a high unmet need, and new targets and treatment modalities are needed. Cevostamab is an IgG1-based T-cell-dependent bispecific antibody engineered to target the most membrane-proximal domain of fragment crystallizable receptor-like 5 (FcRH5) on myeloma cells, and cluster of differentiation 3 (CD3) on T cells. This dual binding results in efficient immunological synapse formation and T-cell-mediated killing of myeloma cells. In the ongoing first-in-human Phase I GO39775 study, intravenous (IV) administration of cevostamab monotherapy continues to show clinically meaningful activity and durable responses in patients with heavily pre-treated R/R MM (Trudel et al. ASH 2021), and uses Cycle (C) 1 step-up dosing for the mitigation of cytokine release syndrome (CRS). Subcutaneous (SC) delivery of antibody therapies has been shown to be effective and well tolerated and offers several advantages over IV administration in regards to improved healthcare utilization, including ease of administration, reduced treatment burden and reduced hospitalization. The slower absorption rate observed with SC versus IV antibody therapies may also support the potential for SC cevostamab to provide a further improved CRS profile (Bartlett et al. ASH 2021). CAMMA 3 (GO43227; ISRCTN26168155) is an open-label, multicenter, Phase Ib dose-escalation and dose-expansion trial evaluating the safety, tolerability, pharmacokinetics (PK) and preliminary activity of SC cevostamab monotherapy in patients with R/R MM. Methods: For inclusion, patients must be aged ≥18 years and must have R/R MM for which no established therapies are available or appropriate. Cevostamab is administered by SC injection in 28-day cycles, with step-up dosing in C1, q2w dosing in C2–6, and q4w dosing in C7–13. Patients may receive up to 13 cycles unless there is disease progression or unacceptable toxicity. Patients who respond to cevostamab but develop recurrent or progressive disease after 13 cycles may be eligible for cevostamab re-treatment. Primary objectives are to evaluate the safety and tolerability (including the maximum tolerated dose and dose-limiting toxicities) of SC cevostamab and to identify a recommended Phase II dose. Secondary objectives include assessment of PK, activity, and immunogenicity, and identification of biomarkers associated with response and resistance. Clinical trial information: 26168155.

CAMMA 1: A multicenter phase Ib trial evaluating the safety, pharmacokinetics, and activity of cevostamab-containing regimens in patients with relapsed or refractory multiple myeloma

TPS8069

Background: Treatment of relapsed/refractory (R/R) multiple myeloma (MM) is challenging, especially in later lines where drug resistance reduces therapeutic options and remission duration. Prognosis is poor (estimated survival: < 1 year) for patients with MM who have received > 3 prior lines of therapy and are triple refractory to immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs) and anti-CD38 agents (Gandhi et al. 2019). Thus R/R MM constitutes a significant unmet medical need. Fragment crystallizable receptor-like 5 (FcRH5) is expressed on myeloma cells with near 100% prevalence (Li et al. 2017), constituting a novel therapeutic target. Cevostamab is an IgG1-based T-cell-engaging bispecific antibody engineered to target the most membrane-proximal domain of FcRH5 on myeloma cells and cluster of differentiation 3 (CD3) on T-cells, resulting in T-cell killing of myeloma cells. Clinical data from the first-in-human Phase I study (GO39775) suggest that cevostamab monotherapy is highly active in heavily pretreated patients with R/R MM, with an overall response rate of 56.7% at the 132–198mg dose level (Trudel et al. ASH 2021 Oral presentation). Thus, cevostamab’s activity and safety profile support further development. Due to their stimulatory effects on T-cell activity, combination of cevostamab with anti-myeloma agents (pomalidomide [P] or daratumumab [D]) may be synergistic, offering the potential to further improve efficacy. CAMMA 1 (NCT04910568) is an open-label, multicenter Phase Ib trial evaluating the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of cevostamab-containing combination regimens (Arm B: cevostamab plus P and dexamethasone [d] [Pd]; Arm C: cevostamab plus Dd) in patients with R/R MM. A modified weekly schedule for cevostamab is also under investigation (Arm A: cevostamab monotherapy). Methods: Patients must be aged ≥18 years, have an ECOG performance status of 0 or 1 and a life expectancy of > 12 weeks. Patients in all arms have R/R MM; Arms B and C include patients with prior IMiD and PI exposure. Patients with prior CAR-T therapy may enroll with a washout period of 12 weeks post-CAR-T infusion. Cevostamab is administered by intravenous infusion q1w (C1–2)/q2w (C3–6)/q4w (C7–13) in Arm A, q2w (C1–6)/q4w (C7+) in Arm B, and q3w (C1–8)/q4w (C9+) in Arm C. Each arm consists of a safety run-in and an expansion cohort. Enrolment for Arm A is ongoing, with patients receiving up to 13 treatment cycles. Arms B and C are planned; patients will receive treatment until disease progression or unacceptable toxicity. The primary objective is to evaluate the safety and tolerability of cevostamab plus Pd, cevostamab plus Dd and cevostamab monotherapy. Secondary objectives include assessment of activity, PK, immunogenicity, and pharmacodynamic biomarkers. Clinical trial information: NCT04910568.

Anti-CD79B Antibody-Drug Conjugate DCDS0780A in Patients with B-Cell Non-Hodgkin Lymphoma: Phase 1 Dose-Escalation Study

PURPOSE

Targeting CD79B using antibody-drug conjugates (ADC) is an effective therapeutic strategy in B-cell non-Hodgkin lymphoma (B-NHL). We investigated DCDS0780A, an anti-CD79B ADC with THIOMAB technology (TDC) that consistently conjugates two anti-neoplastic molecules per antibody, in contrast with ADCs with heterogeneous loads.

PATIENTS AND METHODS

This phase 1 study enrolled 60 patients with histologically confirmed B-NHL that had relapsed/failed to respond following ≥1 prior treatment regimens; 41 (68%) had diffuse large B-cell lymphoma (DLBCL). Fifty-one patients received DCDS0780A monotherapy once every 3 weeks (0.3-4.8 mg/kg); 9 received combination therapy (3.6-4.8 mg/kg) with rituximab.

RESULTS

Fifty-four (90%) patients experienced adverse events related to study drug, the most common of which were blurred vision, fatigue, corneal deposits, neutropenia, nausea, and peripheral neuropathy. 4.8 mg/kg was the highest dose tested and the recommended phase II dose. The pharmacokinetic profile was linear at doses ≥1.2 mg/kg. Response rate in all-treated patients (N = 60) was 47% (n = 28), including 17 complete responses (28%) and 11 partial responses (18%). The median duration of response (15.2 months) was the same for all responders (n = 28) and patients with DLBCL (n = 20).

CONCLUSIONS

DCDS0780A as the TDC format for CD79B was tested at higher doses than its ADC counterpart investigated earlier, leading to deep responses. However, dose intensity was limited by ocular toxicities seen at the higher doses indicating that the TDC format was unable, in the current study, to expand the therapeutic index for the CD79B target. The encouraging antitumor activity advocates continuation of investigations into novel ADC technologies.

Population Pharmacokinetics and Exposure-Response Analyses for Venetoclax in Combination with R-CHOP in Relapsed/Refractory and Previously Untreated Patients with Diffuse Large B Cell Lymphoma

Introduction

Outcomes remain poor in patients with diffuse large B cell lymphoma (DLBCL) who overexpress BCL-2 protein. We present population pharmacokinetics (PopPK) and exposure–response (ER) analyses for venetoclax (a selective BCL-2 inhibitor) administered with rituximab-cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with relapsed/refractory (R/R) and previously untreated (1L) non-Hodgkin lymphoma (NHL) from the phase 1b/2 CAVALLI study, to confirm dose selection for future studies.

Methods

Analyses included 216 patients with R/R or 1L NHL treated for eight 21-day cycles with 400–800 mg venetoclax (cycle 1: days 4–10; cycles 2–8: days 1–10) in combination with R for eight cycles and CHOP for 6–8 cycles. A legacy PopPK model for venetoclax was used to describe the observed data and provide post hoc PK parameters. Venetoclax steady-state exposure (AUC_ss) was used to predict clinical efficacy, safety, or tolerability. To isolate the effect of venetoclax, ER analyses referenced data from the R-CHOP arm of a historical control study, GOYA, in 1L DLBCL.

Results

There was no significant association between venetoclax AUC_ss and progression-free survival or complete response either for all-comers or the BCL-2-immunohistochemistry-positive subpopulation. No statistically significant trends were observed with venetoclax AUC_ss and the key grade ≥ 3 adverse events and serious adverse events. Similar dose intensities were observed for venetoclax and R-CHOP components across venetoclax exposures, suggesting venetoclax did not impact delivery of the R-CHOP backbone.

Conclusions

The PopPK and ER analyses, in addition to the positive benefit–risk observed in the clinical data, support the selection of 800 mg venetoclax given with R-CHOP for future studies in BCL-2-immunohistochemistry-positive patients with 1L DLBCL.

Trial Registration

ClinicalTrials.gov Identifier NCT02055820.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01919-z.

Impact of Physiologically Based Pharmacokinetics, Population Pharmacokinetics and Pharmacokinetics/Pharmacodynamics in the Development of Antibody-Drug Conjugates

Antibody‐drug conjugates are important molecular entities in the treatment of cancer, with 8 antibody‐drug conjugates approved by the US Food and Drug Administration since 2000 and many more in early‐ and late‐stage clinical development. These conjugates combine the target specificity of monoclonal antibodies with the potent anticancer activity of small‐molecule therapeutics. The complex structure of antibody‐drug conjugates poses unique challenges to pharmacokinetic (PK) and pharmacodynamic (PD) characterization because it requires a quantitative understanding of the PK and PD properties of multiple different molecular species (eg, conjugate, total antibody, and unconjugated payload) in different tissues. Quantitative clinical pharmacology using mathematical modeling and simulation provides an excellent approach to overcome these challenges, as it can simultaneously integrate the disposition, PK, and PD of antibody‐drug conjugates and their components in a quantitative manner. In this review, we highlight diverse quantitative clinical pharmacology approaches, ranging from system models (eg, physiologically based pharmacokinetic [PBPK] modeling) to mechanistic and empirical models (eg, population PK/PD modeling for single or multiple analytes, exposure‐response modeling, platform modeling by pooling data across multiple antibody‐drug conjugates). The impact of these PBPK and PK/PD models to provide insights into clinical dosing justification and inform drug development decisions is also highlighted.

Abstract 641: Clinical assessment of the bioavailability of venetoclax tablet and powder formulations

Venetoclax is a first in class BCL-2 inhibitor that is approved for treatment of CLL and AML. It is currently under evaluation in other indications in adult and pediatric populations. Venetoclax is available as 10 mg, 50 mg, and 100 mg film-coated tablets. While the 100 mg tablet is most commonly used, the smaller size of the lower strength tablets is preferred by patients experiencing difficulty swallowing large tablets. Moreover, two powder formulations for suspension (0.72% and 7.2%) to be mixed with delivery vehicles were developed. In this abstract we present data from clinical studies that evaluated the bioavailability of the different venetoclax formulations relative to the commercially available 100 mg tablet. Three open-label, single-dose, crossover bioavailability studies in healthy female subjects were conducted. The first study evaluated the bioavailability of the commercially available 10 and 50 mg tablets relative to the 100 mg tablet. Forty subjects received a 100 mg dose of venetoclax (1x100 mg tablet, 2x50 mg tablets or 10x10 mg tablets) at the start of each period after a low-fat breakfast. The second study evaluated the bioavailability of the two powder formulations relative to the 100 mg tablet. Sixteen subjects received a 100 mg dose of venetoclax (1x100 mg film-coated tablet; 100 mg 0.72% powder formulation; 100 mg 7.2% powder formulation; and 4x25 mg dispersible tablets for oral suspension used in the Phase 1 study) in each of the 4 periods after a high fat breakfast. The third study evaluated the bioavailability of the two powder formulations when administered with different dosing vehicles relative to water. Twenty-four subjects (12 per cohort) received 100 mg of venetoclax (0.72% powder formulation or the 7.2% powder formulation) with either water, apple juice, apple sauce or yogurt in each of the 4 periods after a moderate fat breakfast. Bioavailability assessment of the commercial tablets demonstrated that ten 10 mg tablets were bioequivalent to one 100 mg tablet, two 50 mg tablets were bioequivalent to one 100 mg tablet, and two 50 mg tablets were bioequivalent to ten 10 mg tablets. The two powder formulations for oral suspension (0.72% and 7.2%) met the bioequivalence criteria (0.80-1.25) to the commercial 100 mg tablet with respect to AUCt and AUC∞, but the lower bound of the 90% CI of the Cmax extended slightly below 0.80. The delivery vehicles (water, apple juice, apple sauce and yogurt) did not affect the bioavailability of venetoclax 0.72% or 7.2% oral suspensions

Citation Format: Mohamed Badawi, Bo Tong, Xin Chen, Tammy Palenski, Su Young Kim, Divya Samineni, David Hoffman, Rajeev Menon, Ahmed Hamed Salem. Clinical assessment of the bioavailability of venetoclax tablet and powder formulations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 641.

Model-Informed Therapeutic Dose Optimization Strategies for Antibody-Drug Conjugates in Oncology: What Can We Learn From US Food and Drug Administration-Approved Antibody-Drug Conjugates?

Antibody–drug conjugates (ADCs) combine the specificity of an antibody with the cytotoxicity of a chemical agent. They represent a rapidly evolving area of oncology drug development and hold significant promise. There are currently nine ADCs on the market, more than half of which gained US Food and Drug Administration approval more recently, since 2019. Despite their enormous promise, the therapeutic window for these ADCs remains relatively narrow, especially when compared with other oncology drugs, such as targeted therapies or checkpoint inhibitors. In this review, we provide a detailed overview of the five dosing regimen optimization strategies that have been leveraged to broaden the therapeutic window by mitigating the safety risks while maintaining efficacy. These include body weight cap dosing; treatment duration capping; dose schedule (e.g., dosing frequency and dose fractionation); response‐guided dosing recommendations; and randomized dose‐finding. We then discuss how the lessons learned from these studies can inform ADC development going forward. Informed application of these dosing strategies should allow researchers to maximize the safety and efficacy for next‐generation ADCs.

A phase 2 study of venetoclax plus R-CHOP as first-line treatment for patients with diffuse large B-cell lymphoma

The phase 2 CAVALLI (NCT02055820) study assessed efficacy and safety of venetoclax, a selective B-cell lymphoma-2 (Bcl-2) inhibitor, with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in first-line (1L) diffuse large B-cell lymphoma (DLBCL), including patients demonstrating Bcl-2 protein overexpression by immunohistochemistry (Bcl-2 IHC+). Eligible patients were ≥18 years of age and had previously untreated DLBCL, Eastern Cooperative Oncology Group performance status ≤2, and International Prognostic Index 2 to 5. Venetoclax 800 mg (days 4-10, cycle 1; days 1-10, cycles 2-8) was administered with rituximab (8 cycles) and cyclophosphamide, doxorubicin, vincristine, and prednisone (6-8 cycles) in 21-day cycles. Primary end points were safety, tolerability, and research_plete response (CR) at end of treatment (EOT). Secondary end points were progression-free survival (PFS) and overall survival. Comparative analyses used covariate-adjusted R-CHOP controls from the GOYA/BO21005 study, an appropriate contemporary benchmark for safety and efficacy. Safety and efficacy analyses included 206 patients. CR rate at EOT was 69% in the overall population and was maintained across Bcl-2 IHC+ subgroups. With a median follow-up of 32.2 months, trends were observed for improved investigator-assessed PFS for venetoclax plus R-CHOP in the overall population (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.43-0.87) and Bcl-2 IHC+ subgroups (HR, 0.55; 95% CI, 0.34-0.89) vs R-CHOP. Despite a higher incidence of grade 3/4 hematologic adverse events (86%), related mortality was not increased (2%). Chemotherapy dose intensity was similar in CAVALLI vs GOYA. The addition of venetoclax to R-CHOP in 1L DLBCL demonstrates increased, but manageable, myelosuppression and the potential of improved efficacy, particularly in high-risk Bcl-2 IHC+ patient subgroups.

Clinical pharmacology of vc-MMAE antibody-drug conjugates in cancer patients: learning from eight first-in-human Phase 1 studies

vc-MMAE antibody–drug conjugates (ADCs) consist of a monoclonal antibody (mAb) covalently bound with a potent anti-mitotic toxin (MMAE) through a protease-labile valine-citrulline (vc) linker. The objective of this study was to characterize the pharmacokinetics (PK) and explore exposure–response relationships of eight vc-MMAE ADCs, against different targets and for diverse tumor indications, using data from eight first-in-human Phase 1 studies. PK parameters of the three analytes, namely antibody-conjugated MMAE (acMMAE), total antibody, and unconjugated MMAE, were estimated using non-compartmental approaches and compared across the eight vc-MMAE ADCs. Relationships between analytes were assessed by linear regression. Exposure–response relationships were explored with key efficacy (objective response rate) and safety (Grade 2+ peripheral neuropathy) endpoints. PK profiles of acMMAE, total antibody and unconjugated MMAE following the first dose of 2.4 mg/kg were comparable across the eight ADCs; the exposure differences between molecules were small relative to the inter-subject variability. acMMAE exposure was strongly correlated with total antibody exposure for all the eight ADCs, but such correlation was less evident between acMMAE and unconjugated MMAE exposure. For multiple ADCs evaluated, efficacy and safety endpoints appeared to correlate well with acMMAE exposure, but not with unconjugated MMAE over the doses tested. PK of vc-MMAE ADCs was well characterized and demonstrated remarkable similarity at 2.4 mg/kg across the eight ADCs. Results from analyte correlation and exposure–response relationship analyses suggest that measurement of acMMAE analyte alone might be adequate for vc-MMAE ADCs to support the clinical pharmacology strategy used during late-stage clinical development.

Physiologically Based Pharmacokinetic Model-Informed Drug Development for Polatuzumab Vedotin: Label for Drug-Drug Interactions Without Dedicated Clinical Trials

Model-informed drug development (MIDD) has become an important approach to improving clinical trial efficiency, optimizing drug dosing, and proposing drug labeling in the absence of dedicated clinical trials. For the first time, we developed a physiologically based pharmacokinetic (PBPK) model-based approach to assess CYP3A-mediated drug-drug interaction (DDI) risk for polatuzumab vedotin (Polivy), an anti-CD79b-vc-monomethyl auristatin E (MMAE) antibody-drug conjugate (ADC). The model was developed and verified using data from the existing clinical DDI study for brentuximab vedotin, a similar vc-MMAE ADC. Analogous to the brentuximab vedotin clinical study, polatuzumab vedotin at the proposed labeled dose was predicted to have a limited drug interaction potential with strong CYP3A inhibitor and inducer. Polatuzumab vedotin was also predicted to neither inhibit nor induce CYP3A. The present work demonstrated a high-impact application using a PBPK MIDD approach to predict the CYP3A-mediated DDI to enable drug labeling in the absence of any dedicated clinical DDI study. The key considerations for the PBPK report included in the Biologics License Application/Marketing Authorization Application submission, as well as the strategy and responses to address some of the critical and challenging questions from the health authorities following the submission are also discussed. Our experience and associated perspective using a PBPK approach to ultimately enable a drug interaction label claim for polatuzumab vedotin in lieu of a dedicated clinical DDI study, as well as the interactions with the regulatory agencies, further provides confidence in applying MIDD to accelerate the registration and approval of new drug therapies.

Abstract 3024: Relationship between venetoclax concentrations and undetectable MRD in patients with chronic lymphocytic leukemia

Minimal residual disease (MRD) is an important clinical endpoint in chronic lymphocytic leukemia (CLL) because it correlates with progression free survival and overall survival. The objective of this work is to investigate the impact of venetoclax (VEN) exposures on undetectable MRD rates in blood and bone marrow (BM) in relapsed/refractory (R/R) CLL patients receiving VEN monotherapy or combination therapy with rituximab (RTX).

Data from a total of 708 patients from four VEN monotherapy studies and one combination Phase 1b study (VEN + 6-9 cycles of RTX) in R/R CLL patients were utilized to perform this analysis. The median number of prior therapies in these studies was 3, 42% of the patients had 17p chromosomal deletion and 28% had prior B-Cell Receptor inhibitor (BCRi) therapy. Blood and BM MRD assessments were available for 70% and 38%, respectively, of patients included in the analysis. Absence of an MRD measurement was assumed as detectable MRD for the purposes of this analysis.

The average concentration (Cavg) of VEN was computed for each patient by fitting a population pharmacokinetic model to the observed VEN concentration data. The model was used to calculate area under the curve and compute Cavg accounting for VEN dose ramp-ups, reductions and interruptions. The relationships between venetoclax Cavg and undetectable MRD rates were assessed by using quartile plots. Logistic regression analyses were also conducted to quantify the exposure-response relationship.

With VEN monotherapy, the undetectable MRD rates in blood and BM increased with the increase in VEN exposures. With VEN + RTX combination treatment, the undetectable MRD rates in blood and BM showed an increase with increasing VEN average concentration, but the benefit saturated with limited increase at exposures beyond 400mg.

Logistic regression analyses indicated statistically significant (p&lt;0.01) relationships between VEN average concentrations and undetectable MRD rates in both blood and BM.

These results demonstrate that higher venetoclax concentrations are associated with higher undetectable MRD rates in both blood and BM. When VEN is combined with RTX, an increase in VEN dose beyond 400mg is unlikely to result in higher undetectable MRD rates.

Citation Format: Sathej Gopalakrishnan, Rajeev Menon, Brenda Chyla, Divya Samineni, Amanda Jacobson, Su Young Kim, Sven Mensing, Ahmed Hamed Salem. Relationship between venetoclax concentrations and undetectable MRD in patients with chronic lymphocytic leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3024.

Phase 1b study of anti-NaPi2b antibody-drug conjugate lifastuzumab vedotin (DNIB0600A) in patients with platinum-sensitive recurrent ovarian cancer

OBJECTIVE

This study investigated the safety and tolerability of lifastuzumab vedotin (DNIB0600A) (LIFA), an antibody-drug conjugate, in patients with recurrent platinum-sensitive ovarian cancer (PSOC).

METHODS

In this open-label, multicenter phase 1b study, LIFA was administered intravenously once every 3 weeks (Q3W) with starting dose 1.2 mg/kg in a 3 + 3 dose-escalation scheme. All patients received carboplatin at dose AUC 6 mg/mL·min (AUC6) Q3W for up to 6 cycles. Dose expansion cohorts were enrolled ± bevacizumab 15 mg/kg Q3W.

RESULTS

Patients received LIFA at 1.2, 1.8, and 2.4 mg (n = 4, 5, and 20, respectively) with carboplatin. The maximum tolerated dose was not reached. The recommended phase 2 dose (RP2D) was LIFA 2.4 mg/kg + carboplatin AUC6 (cycles 1-6), with or without bevacizumab 15 mg/kg. Twelve patients received RP2D with bevacizumab. All patients experienced ≥1 adverse event (AE). The most common treatment-related AEs were neutropenia, peripheral neuropathy, thrombocytopenia, nausea, fatigue, anemia, diarrhea, vomiting, hypomagnesaemia, aspartate aminotransferase increased, alanine aminotransferase increased, and alopecia. Thirty-four (83%) patients experienced grade ≥ 3 AEs, the most frequent of which were neutropenia and thrombocytopenia. Nine (22%) patients experienced serious AEs. Pulmonary toxicities (34%), considered a potential risk of LIFA, included one patient who discontinued study treatment due to grade 2 pneumonitis. The median duration of progression-free survival was 10.71 months (95% CI: 8.54, 13.86) with confirmed complete/partial responses in 24 (59%) patients. Pharmacokinetics of mono-therapy LIFA was similar in combination therapy.

CONCLUSION

LIFA in combination with carboplatin ± bevacizumab demonstrated acceptable safety and encouraging activity in PSOC patients.

Time-to-Event Modeling of Peripheral Neuropathy: Platform Analysis of Eight Valine-Citrulline-Monomethylauristatin E Antibody-Drug Conjugates

Peripheral neuropathy (PN) is a common long-term debilitating toxicity of antimicrotubule agents. PN was the most frequent adverse event resulting in dose modifications and/or discontinuation of treatment for valine-citrulline-monomethylauristatin E antibody-drug conjugates (ADCs) developed at Genentech. A pooled time-to-event analysis across eight ADCs (~700 patients) was performed to evaluate the relationship between the ADC exposure and the risk for developing a clinically significant (grade ≥ 2) PN. In addition, the impact of demographic and pathophysiological risk factors on the risk for PN was explored. The time-to-event analysis suggested that the development of PN risk increased with ADC exposure, treatment duration, body weight, and previously reported PN. This model can be used to inform clinical strategies such as adaptations to dosing regimen and/or treatment duration as well as inform clinical eligibility to reduce the incidence of grade ≥ 2 PN.

Prediction of Human Pharmacokinetics of Antibody-Drug Conjugates From Nonclinical Data

Prediction of human pharmacokinetics (PK) based on preclinical information for antibody–drug conjugates (ADCs) provide important insight into first‐in‐human (FIH) study design. This retrospective analysis was conducted to identify an appropriate scaling method to predict human PK for ADCs from animal PK data in the linear range. Different methods for projecting human clearance (CL) from animal PK data for 11 ADCs exhibiting linear PK over the tested dose ranges were examined: multiple species allometric scaling (CL vs. body weight), allometric scaling with correction factors, allometric scaling based on rule of exponent, and scaling from only cynomolgus monkey PK data. Two analytes of interest for ADCs, namely total antibody and conjugate (measured as conjugated drug or conjugated antibody), were assessed. Percentage prediction errors (PEs) and residual sum of squares (RSS) were compared across methods. Human CL was best estimated using cynomolgus monkey PK data alone and an allometric scaling exponent of 1.0 for CL. This was consistently observed for both conjugate and total antibody analytes. Other scaling methods either underestimated or overestimated human CL, or produced larger average absolute PEs and RSS. Human concentration‐time profiles were also reasonably predicted from the cynomolgus monkey data using species‐invariant time method with a fixed exponent of 1.0 for CL and 1.0 for volume of distribution. In conclusion, results from this retrospective analysis of 11 ADCs indicate that allometric scaling of CL with an exponent of 1.0 using cynomolgus monkey PK data alone can successfully project human PK profiles of an ADC within linear range.

Phase I study of the anti-FcRH5 antibody-drug conjugate DFRF4539A in relapsed or refractory multiple myeloma

FcRH5 is a cell surface marker enriched on malignant plasma cells when compared to other hematologic malignancies and normal tissues. DFRF4539A is an anti-FcRH5 antibody-drug conjugated to monomethyl auristatin E (MMAE), a potent anti-mitotic agent. This phase I study assessed safety, tolerability, maximum tolerated dose (MTD), anti-tumor activity, and pharmacokinetics of DFRF4539A in patients with relapsed/refractory multiple myeloma. DFRF4539A was administered at 0.3-2.4 mg/kg every 3 weeks or 0.8-1.1 mg/kg weekly as a single-agent by intravenous infusion to 39 patients. Exposure of total antibody and antibody-conjugate-MMAE analytes was linear across the doses tested. There were 37 (95%) adverse events (AEs), 8 (21%) serious AEs, and 15 (39%) AEs ≥ grade 3. Anemia (n = 10, 26%) was the most common AE considered related to DFRF4539A. Two cases of grade 3 acute renal failure were attributed to DFRF4539A. There were no deaths; the MTD was not reached. DFRF4539A demonstrated limited activity in patients at the doses tested with 2 (5%) partial response, 1 (3%) minimal response, 18 (46%) stable disease, and 16 (41%) progressive disease. FcRH5 was confirmed to be expressed and occupied by antibody post-treatment and thus remains a valid myeloma target. Nevertheless, this MMAE-based antibody-drug-conjugate targeting FcRH5 was unsuccessful for myeloma.

Development and Translational Application of an Integrated, Mechanistic Model of Antibody-Drug Conjugate Pharmacokinetics

Antibody drug conjugates (ADC), in which small molecule cytotoxic agents are non-specifically linked to antibodies, can enable targeted delivery of chemotherapeutics to tumor cells. ADCs are often produced and administered as a mixture of conjugated antibodies with different drug to antibody ratios (DAR) resulting in complex and heterogeneous disposition kinetics. We developed a mechanism-based platform model that can describe and predict the complex pharmacokinetic (PK) behavior of ADCs with protease-cleavable valine-citrulline (VC) linker linked to Monomethylmonomethyl auristatin F/E by incorporating known mechanisms of ADC disposition. The model includes explicit representation of all DAR species; DAR-dependent sequential deconjugation of the drug, resulting in the conversion of higher DAR to lower DAR species; and DAR-dependent antibody/ADC clearance. PK profiles of multiple analytes (total antibody, drug-conjugated antibody, and/or antibody-conjugated drug) for different ADC molecules and targets in rodents and cynomolgus monkeys were used for model development. The integrated cross-species model was successful in capturing the multi-analyte PK profiles after administration of purified ADCs with defined DAR species and ADCs with mixtures of DAR. Human PK predictions for DSTP3086S (anti-STEAP1-vc-MMAE) with the platform model agreed well with PK (total antibody and antibody-conjugated drug concentrations) measurements in the dose-ranging phase I clinical study. The integrated model is applicable to various other ADCs with different formats, conjugated drugs, and linkers, and provides a valuable tool for the exploration of mechanisms governing disposition of ADCs and enables translational predictions.

A randomized trial of the efficacy and safety of quilizumab in adults with inadequately controlled allergic asthma

Background

Quilizumab, a humanized IgG1 monoclonal antibody, targets the M1-prime segment of membrane-expressed IgE, leading to depletion of IgE-switched and memory B cells. In patients with mild asthma, quilizumab reduced serum IgE and attenuated the early and late asthmatic reaction following whole lung allergen challenge. This study evaluated the efficacy and safety of quilizumab in adults with allergic asthma, inadequately controlled despite high-dose inhaled corticosteroids (ICS) and a second controller.

Methods

Five hundred seventy-eight patients were randomized to monthly or quarterly dosing regimens of subcutaneous quilizumab or placebo for 36 weeks, with a 48-week safety follow-up. Quilizumab was evaluated for effects on the rate of asthma exacerbations, lung function, patient symptoms, serum IgE, and pharmacokinetics. Exploratory analyses were conducted on biomarker subgroups (periostin, blood eosinophils, serum IgE, and exhaled nitric oxide).

Results

Quilizumab was well tolerated and reduced serum total and allergen-specific IgE by 30–40 %, but had no impact on asthma exacerbations, lung function, or patient-reported symptom measures. At Week 36, the 300 mg monthly quilizumab group showed a 19.6 % reduction (p = 0.38) in the asthma exacerbation rate relative to placebo, but this was neither statistically nor clinically significant. Biomarker subgroups did not reveal meaningful efficacy benefits following quilizumab treatment.

Conclusions

Quilizumab had an acceptable safety profile and reduced serum IgE. However, targeting the IgE pathway via depletion of IgE-switched and memory B cells was not sufficient for a clinically meaningful benefit for adults with allergic asthma uncontrolled by standard therapy.

Trial registration

ClinicalTrials.gov NCT01582503

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0347-2) contains supplementary material, which is available to authorized users.

Phase I Study of DMOT4039A, an Antibody-Drug Conjugate Targeting Mesothelin, in Patients with Unresectable Pancreatic or Platinum-Resistant Ovarian Cancer

DMOT4039A, a humanized anti-mesothelin mAb conjugated to the antimitotic agent monomethyl auristatin E (MMAE), was given to patients with pancreatic and ovarian cancer every 3 weeks (0.2-2.8 mg/kg; q3w) or weekly (0.8-1.2 mg/kg). A 3+3 design was used for dose escalation followed by expansion at the recommended phase II dose (RP2D) to evaluate safety and pharmacokinetics. Antitumor response was evaluated per RECIST 1.1 and serum CA19-9 or CA125 declines. Tumor mesothelin expression was determined by IHC. Seventy-one patients (40 pancreatic cancer; 31 ovarian cancer) were treated with DMOT4039A. For the q3w schedule (n = 54), the MTD and RP2D was 2.4 mg/kg, with dose-limiting toxicities of grade 3 hyperglycemia and grade 3 hypophosphatemia at 2.8 mg/kg. For the weekly schedule (n = 17), the maximum assessed dose was 1.2 mg/kg, with further dose escalations deferred because of toxicities limiting scheduled retreatment in later cycles, and therefore the RP2D level for the weekly regimen was determined to be 1 mg/kg. Across both schedules, the most common toxicities were gastrointestinal and constitutional. Treatment-related serious adverse events occurred in 6 patients; 4 patients continued treatment following dose reductions. Drug exposure as measured by antibody-conjugated MMAE and total antibody was generally dose proportional over all dose levels on both schedules. A total of 6 patients had confirmed partial responses (4 ovarian; 2 pancreatic) with DMOT4039A at 2.4 to 2.8 mg/kg i.v. q3w. DMOT4039A administered at doses up to 2.4 mg/kg q3w and 1.0 mg/kg weekly has a tolerable safety profile and antitumor activity in both pancreatic and ovarian cancer.

Quantification of human hepatocyte cytochrome P450 enzymes and transporters induced by HIV protease inhibitors using newly validated LC-MS/MS cocktail assays and RT-PCR

Human immunodeficiency virus (HIV) protease inhibitors (PIs) produce profound and unpredictable drug-drug interactions (DDIs) that cannot be explained fully by their inhibition/inactivation of CYP3A enzymes. Delineating and quantifying the CYPs and transporters inducible by PIs are crucial in developing an integrative mechanistic understanding and prediction of PI-based DDIs. To do so, two LC-MS/MS cocktail assays were modified and validated simultaneously to quantify the CYP activity of CYP3A, 2B6, 2C8, 2C9, 2C19, 1A, 2E1, 2A6 and 2D6 enzymes. These new assays were applied to evaluate the induction potential of eight PIs in microsomes isolated from PI-treated human hepatocytes. The mRNA expression of these CYPs and transporters (OATP1B1, OATP1B3, OATP1A2, MDR1, MRP2 and MRP4) was also evaluated using relative RT-PCR. The majority of PIs were net inducers of CYP3As and 2B6 at both the mRNA and activity level (> 2-fold), while ritonavir, saquinavir, nelfinavir or lopinavir did not induce CYP3A activity (< 2-fold), presumably due to CYP3A inactivation. OATP1B1 and MDR1 were the only two hepatic transporters induced (> 2-fold) by the PIs. Amprenavir was the most potent net inducer. In conclusion, our validated cocktail assays can be implemented to comprehensively quantify CYP activities in human liver microsomes and hepatocyte studies. The results also provide the much needed data on the net induction potential of the PIs for hepatic CYPs and transporters. A qualitative agreement was observed between our results and published PI-based DDIs, suggesting that human hepatocytes are a useful platform for more extensive and quantitative in vitro-in vivo prediction of PI-based DDIs.

Brain distribution and elimination of recombinant human TIMP-1 after cerebral ischemia and reperfusion in rats

OBJECTIVE

To investigate recombinant human TIMP-1 ((125)I-rhTIMP-1) half-life in blood and its distribution in rat brain tissue after cerebral ischemia/reperfusion as part of a therapeutic development paradigm.

METHOD

A suture model of the middle cerebral artery occlusion was used. (125)I-labeled rhTIMP-1 at 60 μg/kg (11.23 μCi/μg) was administered to rats intravenously at the beginning of reperfusion. Blood and brain tissue were collected. The radioactivity was detected with a gamma counter and analyzed by autoradiography.

RESULTS

The blood half-life T(1/2) of (125)I-rhTIMP-1 was 42.2 hours. Thirty minutes after (125)I-rhTIMP-1 administration, an increased accumulation of (125)I-rhTIMP-1 in the ischemic hemisphere was observed. The maximum brain tissue concentration C(max) was 26.1 ng/g at 1.5 hours in the striatum and 13.9 ng/g at 5 hours in the cortex when the uptake percentage of brain tissue to blood was 6.1±0.4 and 6.7±2.1%, respectively. The cortex and striatum elimination half-lives T(1/2) were 45.3 and 39.2 hours, respectively. Electrophoretic analysis of ischemic samples for (125)I-rhTIMP-1 showed a clear 28 kDa band 1.5 hours after (125)I-rhTIMP-1 administration in the cortex and striatum. The intensity of the 28 kDa band decreased after 3.0 hours of the administration. Some (125)I-rhTIMP-1 maintained its molecular integrity for 8.5 hours in ischemic striatum after reperfusion.

DISCUSSION

(125)I-labeled rhTIMP-1 was distributed quickly into ischemic brain tissue and had a slow elimination in both blood and brain tissue. These results, along with other studies suggesting therapeutic benefits, will aid in the development of TIMP-1 for protecting ischemic stroke.

Steady-state pharmacokinetic interactions of darunavir/ritonavir with lipid-lowering agent rosuvastatin

HIV-1 protease inhibitors often cause dyslipidemia, necessitating the use of lipid-lowering agents such as rosuvastatin. However, when given concomitantly, these therapeutic agents often exhibit adverse drug interactions. In this study (phase I open-label trial, n = 12 HIV-1 seronegative participants), the authors assessed the drug interactions between darunavir/ritonavir given in combination with rosuvastatin. Participants were randomized to receive rosuvastatin (10 mg/day) or darunavir/ritonavir (600/100 mg twice daily) alone for 7 days in a crossover design followed by combination therapy for 7 days with intervening 7-day washout periods. Intensive blood sampling for pharmacokinetics and fasting lipids was performed on days 7, 21, and 35. The geometric mean AUC(0-24 h) of rosuvastatin increased from 109 to 161 ng·h/mL (P < .005) and C(max) increased 6.7 to 16.3 ng/mL (P < .001) when coadministered with darunavir/ritonavir. In the presence of darunavir/ritonavir and rosuvastatin, total cholesterol and triglyceride levels increased by 10% (P = .007) and 56% (P = .011), whereas the high-density lipoprotein cholesterol levels decreased by 13% (P = .006) relative to rosuvastatin administration alone. There were no significant adverse events attributable to the coadministration of these drugs. Rosuvastatin levels increase in the presence of darunavir/ritonavir coadministration, whereas the lipid-lowering benefits are blunted. The clinical significance of these changes requires further investigation.

Fenofibrate in the treatment of dyslipidemia associated with HIV infection

IMPORTANCE TO THE FIELD

Dyslipidemia is common among HIV-infected patients receiving antiretroviral therapy. A higher risk of coronary heart disease (CHD) is associated with specific antiretroviral medications. The aging of HIV infected people and the intersection of other CHD risk factors have led to the need for developing effective interventions to lower the risk of CHD events.

AREAS COVERED IN THIS REVIEW

The authors review current literature on the use of fenofibrate and related derivatives in HIV-infected people with dyslipidemia using antiretroviral therapy.

WHAT THE READER WILL GAIN

Fibrates have been demonstrated to reduce the risk of CHD events in HIV seronegative individuals with mixed results on survival benefits. There are no published studies of CHD outcomes using fibrates in people with HIV infection. Several studies conducted in HIV infected people demonstrate the ability of fenofibrate to lower triglycerides and increase high-density lipoprotein cholesterol levels with few adverse events. The authors review the pharmacology and clinical efficacy/safety of the use of fenofibrate in people with HIV infection.

TAKE HOME MESSAGE

Fenofibrate is a generally safe and useful agent for the treatment of mixed dyslipidemia and hypertriglyceridemia in people with HIV infection though limited data are available particularly on clinical outcomes.