The addition of nivolumab and docetaxel to androgen deprivation therapy (ADT) induced antitumor activity in patients with metastatic castration-resistant prostate cancer (mCRPC) regardless of prior novel antiandrogen therapy (NAT) use, according to final analysis results from arm B of the phase 2 CheckMate 9KD trial presented at the 2021 Genitourinary Cancers Symposium.

Nivolumab monotherapy has had limited efficacy against mCRPC, but docetaxel may enhance antitumor responses. Arm B of the CheckMate9KD trial (NCT03338790) tested this combination in patients who had and had not received prior NAT.

Arm B enrolled 84 patients with chemotherapy-naïve mCRPC who were receiving ADT and had received no more than 2 prior NATs. The coprimary end points were objective response rate (ORR) and prostate-specific antigen response rate (PSA-RR), defined as a 50% or greater PSA reduction. Secondary end points included radiographic progression-free survival (rPFS), overall survival (OS), and safety.

At baseline, the median age was 71 years. Measurable disease and visceral disease were present in 54% and 27% of patients, respectively. The median number of docetaxel cycles was 8; the median number of nivolumab doses was 11.


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At a median follow-up of 15.2 months, the ORR was 40.0% (95% CI, 25.7-55.7). The ORR was similar in patients who received prior NAT (38.7%) and those who did not (42.9%). A complete response was achieved by 2.2% of patients and a partial response, by 37.8% of the 45 patients with measurable disease.

The median rPFS was 9.0 months, which was also similar between patients who had and had not received prior NAT (8.5 vs 12.0 months). The median OS was 18.2 months. Among patients who had prior NAT, the median OS was 16.2 months. The median OS had not been reached in patients with no history of NAT.

The confirmed PSA-RR was achieved by 46.9% of patients overall, including 39.6% of patients who had prior NAT and 60.7% of patients who did not.

Grade 3 to 4 treatment-related adverse events (TRAEs) presented in 47.6% of patients. The most common TRAE was neutropenia (16.7%). TRAEs led 29.8% of patients to discontinue treatment.

Gastrointestinal (35.7%) and skin-related (26.2%) events were the most common immune-related AEs. One case of nivolumab-related pneumonitis and 2 cases of pneumonia due to docetaxel resulted in a total of 3 deaths.

“Nivolumab plus docetaxel has encouraging clinical activity in patients with chemotherapy-naïve mCRPC, regardless of prior NAT, with a safety profile consistent with those of the individual agents,” concluded Karim Fizazi, MD, PhD, who presented the findings.

Disclosures: Some of the study authors disclosed financial relationships with the pharmaceutical industry and/or the medical device industry. For a full list of disclosures, please refer to the original study. This clinical trial was supported by Bristol Myers Squibb.

Reference

Fizazi K, Mella PG, Castellano D, et al. CheckMate 9KD Arm B final analysis: Efficacy and safety of nivolumab plus docetaxel for chemotherapy-naïve metastatic castration-resistant prostate cancer. Presented at: 2021 Genitourinary Cancers Symposium; February 11-13, 2021. Abstract 12.

This article originally appeared on Cancer Therapy Advisor