Role of obinutuzumab exposure on clinical outcome of follicular lymphoma treated with first-line immunochemotherapy

Aims: Obinutuzumab (G) is a humanized type II, Fc-glycoengineered anti-CD20 monoclonal antibody used in various indications, including patients with previously untreated front-line follicular lymphoma. We investigated sources of variability in G exposure and association of progression-free survival (PFS) with average concentration over induction (C meanIND ) in front-line follicular lymphoma patients treated with G plus chemotherapy (bendamustine, CHOP, or CVP) in the GALLIUM trial. Methods: Individual exposures (C meanIND ) were obtained from a previously established population pharmacokinetic model updated with GALLIUM data. Multivariate Cox proportional hazard models and univariate Kaplan–Meier plots investigated relationships of PFS with exposure and other potential prognostic factors. Results: Overall, G exposure was lower in high body-weight patients and in males, and slightly lower in patients with high baseline tumour burden. Analysis of clinical outcomes showed that variability in G exposure did not impact PFS in G-bendamustine-treated patients; PFS was inferior in males and patients with FCGR2a/2b T232 T low-affinity receptor variant, and superior in patients with FCGR2a/2b I232T variant. In G-CHOP/CVP arms, PFS improved with increasing C meanIND (hazard ratio = 1.74 and 0.394 at 5 th and 95 th percentile compared to median C meanIND ) and was inferior in patients with high baseline tumour size and B symptoms. Conclusions: It remains unclear whether for G-CHOP/CVP patients lower G exposure is a consequence of adverse disease biology and/or resistance to chemotherapy backbone (higher clearance in nonresponder patients, as demonstrated for rituximab) rather than being the cause of poorer clinical outcome. A study with &gt;1 dose level of G could help resolve this uncertainty. </p

Exposure‐safety and exposure‐efficacy analyses for tisotumab vedotin for patients with locally advanced or metastatic solid tumors

Abstract The antibody‐drug conjugate (ADC) tisotumab vedotin (TV) received accelerated approval from the US Food and Drug Administration for treatment of adults with recurrent or metastatic cervical cancer (r/mCC) with disease progression on or after chemotherapy. A population pharmacokinetic (PK) model, developed using dosing data from four clinical TV studies, was used to estimate individual exposure and explore safety and efficacy exposure‐response (ER) relationships. Because PK analysis showed no appreciable accumulation of TV and monomethyl auristatin E (MMAE) with repeated dosing, cycle 1 exposure metrics and predicted average concentrations from time zero until end of the cycle in which an event occurred (CavgLast) were used for ER analyses. The probability of achieving objective response increased significantly as the ADC cycle 1 maximum serum concentration (Cmax) increased. The probability of treatment‐related adverse events (AEs) leading to dose modification increased significantly as ADC cycle 1 area under the concentration‐time curve (AUC) increased. Number of grade 2+ ocular AEs increased significantly as ADC cycle 1 AUC, Cmax, and ADC CavgLast increased. MMAE cycle 1 AUC predicted risk of serious treatment‐related AEs. The relationship between ADC exposure and efficacy end points suggests ADC treatment was associated with clinically meaningful response across the observed exposures; greater exposure was associated with increased efficacy. The relationship between ADC and MMAE exposure and safety end points suggests increased exposure was associated with increased AE risk. These results align with clinical findings showing TV 2 mg/kg (≤200 mg for patients ≥100 kg) every 3 weeks is efficacious and tolerable for patients with r/mCC