The response-based addition of ipilimumab to nivolumab in the treatment of advanced renal cell carcinoma (RCC) resulted in few responses among patients who did not achieve a response with nivolumab alone, according to results of a phase 2 trial. These findings were presented at the ASCO20 Virtual Scientific Program.
“We hypothesized that the addition of CTLA-4 blockade may not be required for all patients,” reported Rana R. McKay, MD, of the University of California San Diego, and lead author and presenter of the study. “Furthermore, the optimal duration of nivolumab maintenance in responding patients is unknown.”
In the phase 2 OMNIVORE trial, 69 patients were treated with nivolumab monotherapy and then allocated to 1 of 2 arms based on their response. Patients with confirmed partial (PR) or complete response (CR) within 6 months discontinued nivolumab and underwent observation, whereas patients with stable or progressive disease at 6 months received 2 doses of ipilimumab. Those who developed progressive disease (PD) after discontinuation of nivolumab were retreated with nivolumab, and ipilimumab was subsequently added if PD persisted.
The primary endpoint for the arm with patients who responded to initial treatment with nivolumab was the proportion of patients who achieved PR or CR at 1 year post treatment discontinuation. The primary endpoint for the arm with patients who required the addition of ipilimumab was the proportion of patients who converted to a PR or CR.
At baseline, the median age of patients was 61 and 96% had clear cell histology. Prior treatment had been given to 49% of patients and 67% of patients were classified as intermediate/poor risk.
During a median follow-up of 19.5 months, 14% of patients receiving nivolumab monotherapy achieved a response, all of which were PRs. These patients subsequently discontinued nivolumab, and 42% remained off therapy for more than 1 year. Nivolumab was restarted in 4 patients after 6 months, 2 of whom required the addition of ipilimumab.
Patients who did not experience an initial response to nivolumab (86%), received ipilimumab, which resulted in conversion to a response in 4%, all of which were PRs.
Overall, the 18-month OS among both arms was 79%.
Grade 3-4 treatment-related adverse events developed in 7% of patients during nivolumab monotherapy and in 25% of patients who went on to receive ipilimumab.
Given that the response-based addition of ipilimumab to nivolumab resulted in low PR/CR conversion rates, Dr McKay said that “Currently, we cannot recommend a strategy of nivolumab followed by response-based addition of ipilimumab.”
Disclosure: Research funding for this study was provided by BMS. For a complete list of author disclosures please refer to the reference.
McKay RR, Xie W, McGregor BA, et al. Optimized management of nivolumab (Nivo) and ipilimumab (Ipi) in advanced renal cell carcinoma (RCC): A response-based phase II study (OMNIVORE). Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr 5005.
This article originally appeared on Cancer Therapy Advisor