Nivolumab plus docetaxel versus placebo plus docetaxel for androgen receptor pathway inhibitor-pretreated and chemotherapy-naive metastatic castration-resistant prostate cancer (CheckMate 7DX): a double-blind, randomised, phase 3 trial.

[BACKGROUND] Androgen receptor pathway inhibitors (ARPIs) and docetaxel are established standards of care for chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC). We aimed to assess the efficacy and safety of adding nivolumab to docetaxel versus docetaxel alone in ARPI-pretreated, chemotherapy-naive mCRPC.

[METHODS] CheckMate 7DX was a double-blind, randomised, phase 3 trial that enrolled adult patients (aged ≥18 years) with histologically confirmed, ARPI-pretreated, and chemotherapy-naive mCRPC at 291 hospitals and cancer centres across 27 countries. Patients had documented progression within 6 months of screening and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients were randomly assigned (1:1) to nivolumab (360 mg), or equivalent placebo, and docetaxel (75 mg/m) intravenously every 3 weeks for up to ten doses, followed by nivolumab (480 mg) or equivalent placebo every 4 weeks. Randomisation, stratified by previous ARPI therapy and visceral disease, was done using interactive response technology in permuted blocks with a block size of six. Patients, investigators, and the trial sponsor were masked to individual patient treatment assignment. The primary endpoints were radiographic progression-free survival by blinded independent central review and overall survival, assessed in all randomly assigned patients. Safety was assessed in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT04100018, and is completed.

[FINDINGS] Between March 11, 2020, and Aug 2, 2022, 1414 patients were screened for eligibility, 1030 of whom were randomly assigned to nivolumab plus docetaxel (n=514) or placebo plus docetaxel (n=516). All participants were male, median age was 70 years (range 34-91), 662 (64%) were White, 240 (23%) were Asian, and 35 (3%) were Black or African American. With a median follow-up of 17·2 months (IQR 13·2-22·0), median radiographic progression-free survival was 9·4 months (95% CI 8·5-10·3) in the nivolumab plus docetaxel group versus 8·7 months (95% CI 8·4-10·0) in the placebo plus docetaxel group (hazard ratio [HR] 0·96 [99% CI 0·77-1·19]; p=0·59) and median overall survival was 18·7 months (95% CI 17·0-21·0) versus 18·9 months (95% CI 17·3-22·0, HR 1·09 [99·41% CI 0·84-1·43]; p=0·36). Grade 3-4 treatment-related adverse events occurred in 223 (44%) of 510 patients in the nivolumab plus docetaxel group and 187 (37%) of 510 in the placebo plus docetaxel group. The most common grade 3-4 events in both treatment groups were neutropenia (37 [7%] in the nivolumab plus docetaxel group and 50 [10%] in the placebo plus docetaxel group) and decreased neutrophil count (41 [8%] and 39 [8%]). Any-grade treatment-related serious adverse events occurred in 107 (21%) patients in the nivolumab plus docetaxel group and 77 (15%) in the placebo plus docetaxel group. 12 deaths were attributed to nivolumab plus docetaxel (three due to sepsis; one each due to Guillain-Barré syndrome, diverticulitis, myocarditis, liver injury, peritonitis, pneumonitis, pneumonia, and diarrhoea; and one due to unknown causes) and one was attributed to placebo plus docetaxel (due to pneumocystis).

[INTERPRETATION] Nivolumab plus docetaxel did not improve progression-free survival or overall survival versus placebo plus docetaxel in patients with ARPI-pretreated, chemotherapy-naive mCRPC. These findings do not support the use of combinations of anti-PD-1 immune checkpoint inhibitors and docetaxel in the treatment of unselected populations of patients with ARPI-pretreated, chemotherapy-naive mCRPC.

[FUNDING] Bristol Myers Squibb.