Posted: Tuesday, February 21, 2023
During the 2023 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract 22), Padmanee Sharma, MD, PhD, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues presented additional results from the CheckMate 650 study, which administered alternative doses of nivolumab plus ipilimumab versus ipilimumab alone versus cabazitaxel in patients with resistant metastatic castration-resistant prostate cancer after chemotherapy. The results of this trial support the use of this immunotherapy combination for some patients in this population, although more expansive biomarker analyses are warranted.
A total of 259 newly enrolled patients who were previously treated with docetaxel for metastatic castration-resistant prostate cancer were the focus. Participants were randomly assigned to receive one of the following regimens: 3 mg/kg of nivolumab plus 1 mg/kg of ipilimumab (group 1, n = 73); 1 mg/kg of nivolumab plus 3 mg/kg of ipilimumab (group 2, n = 74); 3 mg/kg of ipilimumab (group 3, n = 38); 20 or 25 mg/m2 of cabazitaxel (group 4, n = 74). Crossover from cohorts 3 and 4 to cohort 1 was allowed upon radiographic progressive disease.
The median follow-up for overall survival was 23.3 months, with objective response rates of 9%, 15%, 4%, and 11% for cohorts 1, 2, 3, and 4, respectively. In group 1, the median duration of therapy was 2.8 months; the median therapy duration in cohort 2 was 2.4 months. The median numbers of ipilimumab doses in groups 1 and 2 were four and two, respectively.
Approximately one-third of patients in groups 3 and 4 crossed over to group 1. In groups 1 and 2, 15% and 26% of patients discontinued study treatment because of toxicity, respectively; two patients died of study drug toxicity. However, multiple patients in cohorts 1 and 2 demonstrated notable reductions in prostate-specific antigen and tumor size.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
2023 ASCO GU Cancers Symposium