Copanlisib population pharmacokinetics from phase I-III studies and exposure-response relationships in combination with rituximab

CHRONOS-4: phase 3 study of copanlisib plus rituximab-based immunochemotherapy in relapsed indolent B-cell lymphoma

ABSTRACT

Copanlisib, a pan-class I phosphatidylinositol 3-kinase inhibitor with predominant activity against the α and δ isoforms, previously demonstrated durable responses as monotherapy and improved progression-free survival (PFS) in combination with rituximab in patients with relapsed indolent non-Hodgkin lymphoma (iNHL). CHRONOS-4 was a phase 3, randomized, double-blind, placebo-controlled study to investigate the efficacy and safety of copanlisib in combination with standard immunochemotherapy in patients with relapsed iNHL. Patients (n = 524) were randomized (1:1) to copanlisib (60 mg IV) plus immunochemotherapy (rituximab and bendamustine [R-B] or placebo plus R-B). Copanlisib/placebo were administered with R-B (days 1, 8, and 15 of each 28-day cycle) for ≤6 cycles and as monotherapy from cycle 7 up to 12 months. The primary study end point was PFS. Median exposure was 8.5 months (0.2-12.9) for copanlisib plus R-B and 11.4 months (0.1-12.6) for placebo plus R-B. Median PFS was 32.9 months (95% confidence interval [CI], 24.4-38.6) for copanlisib plus R-B and 33.3 months (95% CI, 27.8-42.8) for placebo plus R-B (hazard ratio, 1.13; 95% CI, 0.88-1.44; P = .83). No differences between treatment arms were observed in overall survival (data not yet mature), objective response rate, and duration of response for the overall population or individual histology types. Overall, copanlisib plus R-B was associated with higher rates of serious treatment-emergent adverse events (TEAEs), grade 4 and 5 TEAEs, and treatment discontinuation. A number of serious TEAEs were infections. Overall, copanlisib plus R-B did not provide clinical benefit vs placebo plus R-B and was associated with worse tolerability in patients with relapsed iNHL. This trial was registered at www.ClinicalTrials.gov as #NCT02626455.

Model-Based Benefit/Risk Analysis for the Copanlisib Intermittent Dosing Regimen

Copanlisib is an intravenously administered phosphatidylinositol 3-kinase (PI3K) inhibitor, which is approved as monotherapy for relapsed follicular lymphoma in adult patients who have received at least two systemic therapies. In an April 2022 US Food and Drug Administration (FDA) Oncology Drug Advisory Committee (ODAC), the benefit-risk profile of the class PI3K inhibitors were scrutinized for use in hematological malignancies. Specifically, their unique toxicities may contribute to the high incidences in reported serious and high-grade treatment emergent adverse events (TEAEs), thereby reducing their overall tolerability and potentially limiting their successful use. These tolerability concerns may be contributed by or compounded by inadequate dose optimization. The recommended dosing regimen of copanlisib 60 mg administered on days 1, 8, and 15 of a 28-day cycle was selected as the maximal tolerated dose (MTD) during phase I. Thus, this analysis sought to justify the copanlisib dose regimen selection. Copanlisib exposure-efficacy relationships were considered from its large phase III trial, CHRONOS-3, whereas copanlisib safety was investigated by pooling data across its two large clinical trials to comprehensively assess its exposure-safety relationships. Results demonstrated a statistically significant positive linear exposure-efficacy relationship at the MTD. Exposure-safety analyses revealed a borderline significant linear relationship for grade ≥3 TEAEs and no significant exposure-safety relationships for other investigated safety end points. The model-based benefit/risk framework considered the established exposure-response models and defined clinical utility function which confirmed the appropriateness of the copanlisib dosing regimen across the range of its achieved exposures.

Copanlisib population pharmacokinetics from phase I-III studies and exposure-response relationships in combination with rituximab

Copanlisib dose selection was established under the maximum tolerated dose paradigm, and no dedicated dose-finding studies have investigated copanlisib dose selection when used in combination with rituximab. In CHRONOS-3, copanlisib plus rituximab demonstrated significantly improved progression-free survival versus placebo plus rituximab in patients with relapsed indolent non-Hodgkin lymphoma (iNHL). We conducted a comprehensive investigation of copanlisib population pharmacokinetics (PopPK) from a pooled analysis of 712 patients across nine copanlisib phase I-III studies and exposure-response (ER) relationships for efficacy and safety from the 1-year follow-up of CHRONOS-3. PopPK analyses examined the impact of demographic, laboratory, and comedication covariates on copanlisib between-patient PK variability. Individual static and time-varying exposure estimates were derived to investigate exposure-efficacy and exposure-safety relationships. Multivariate Cox proportional hazards and logistic regression analyses examined ER relationships with consideration of predefined potentially prognostic demographic-, laboratory-, and/or disease-related baseline covariates. Copanlisib PK were best described by a three-compartment model with first-order elimination. Individual identified covariates had modest effects on copanlisib PK and were generally in line with known copanlisib disposition properties. In CHRONOS-3, ER analyses showed a significant relationship between time-varying exposure estimates and progression-free survival, and no significant exposure-safety relationships. Thus, lower copanlisib doses may result in reduced efficacy but not necessarily improved safety or tolerability. These outcomes substantiate the current intermittent dosing regimen of copanlisib 60 mg on days 1, 8, and 15 of a 28-day cycle and support the observed clinical results of copanlisib in combination with rituximab in the iNHL population.