Ipilimumab with Nivolumab in molecular-Selected patients with castration-resistant PRostate cancer: primary analysis of the Phase 2 INSPIRE trial
Mené sur 69 patients atteints d'un cancer métastatique de la prostate résistant à la castration et présentant une déficience du système de réparation MMR, une charge mutationnelle tumorale supérieure ou égale à 7,1 mutations/Mégabase, une mutation au niveau du gène BRCA2 ou une inactivation bi-allélique du gène CDK12, cet essai de phase II évalue l'efficacité, du point de vue du taux de contrôle de la maladie après 6 mois, et la toxicité d'un traitement combinant ipilimumab et nivolumab
Résumé en anglais
Background: Metastatic castration-resistant prostate cancer (mCRPC) typically exhibits resistance to immune checkpoint inhibitors (ICIs). However, a subset of mCRPC patients displays a more immunogenic profile. This study examines efficacy and safety of dual ICI therapy in molecularly selected mCRPC.
Patients and methods: This single-arm, phase II trial, included 69 molecularly selected mCRPC patients with mismatch repair deficiency (MMRd), non-synonymous tumour mutational burden ≥7.1 muts/Mb (hTMB), a BRCA2 mutation (BRCAm), or biallelic CDK12 inactivation (CDK12i). Efficacy was assessed in ICI-naïve patients (cohort A) with RECIST1.1 (A1) and PCWG3 (A2) measurable disease. Safety was evaluated in cohorts A and B (prior ICI monotherapy). Treatment included nivolumab 3 mg/kg and ipilimumab 1 mg/kg every 3 weeks for 4 cycles, followed by nivolumab 480 mg every 4 weeks for up to 1 year. The primary endpoint was disease control rate beyond 6 months (DCR>6), aiming to surpass a DCR>6 of 22%.
Results: Patients initiated treatment between January 2021 and February 2024. Cohort A included 65 patients. Of these, 21 had MMRd (32%), 8 hTMB (12%), 20 BRCAm (31%), and 16 CDK12i (25%). DCR>6 was achieved in 38% (95% CI 27-51), and was highest in MMRd (81%), followed by hTMB (25%), CDK12i (19%), and BRCAm (15%). Objective and PSA50 response rates in cohort A were 38% (95% CI 22-55) and 47% (95% CI 34-60), respectively. Median progression-free survival was 4.0 months (95% CI 3.5–12.0) in cohort A, and 32.7 months (95% CI 21.8–NR) in MMRd patients. Treatment-related adverse events (TRAEs) led to permanent discontinuation in 14 of 69 patients (20%). Grade ≥3 TRAEs occurred in 48% of patients, with diarrhoea and elevated transaminases each in 10%. There was one treatment-related death due to a bowel perforation and a second following euthanasia after grade 4 toxicity.
Conclusions: This trial of dual ICIs in molecularly selected mCRPC met its primary endpoint, showing DCR>6 in 40% of patients. Dual ICIs exhibited modest responses in the hTMB, BRCAm and CDK12i subgroups, but demonstrated exceptional efficacy in MMRd.
