Benoit Rousseau, MD, PhD, of Memorial Sloan Kettering Cancer Center, New York, called the findings of the phase II GERCOR NIPICOL trial “interesting and convincing.” Long-term follow-up showed the 3-year progression-free survival rate to be 70% after just 1 total year of treatment with nivolumab plus ipilimumab in patients with chemotherapy-resistant metastatic colorectal cancer whose tumors were microsatellite instability–high or mismatch repair–deficient (MSI-H/dMMR).

During the 2022 ASCO Gastrointestinal Cancers Symposium, several attendees asked if 1 year of immunotherapy should become the standard of care. “It’s a good question, but the data are limited,” Dr. Rousseau said.

He emphasized that this study assessed the doublet of ipilimumab plus nivolumab, which yielded a response rate of about 60%—higher than the 25% to 45% reported for single-agent anti–PD-1 in the second line or greater. Pembrolizumab is now more likely to be used in the first line, as it has recently become a standard of care for these patients. “It’s difficult to compare monotherapy and the doublet, as the mechanism of action and responses are different with the anti–CTLA-4 agent [ipilimumab],” he said.

Benoit Rousseau, MD, PhD

Patient Discussion

Dr. Rousseau said he might consider shortening the treatment duration of nivolumab plus ipilimumab, however, if patients requested it—as they sometimes do when they are doing well. “In my opinion, if discussed with the patient, it might be considered an option. Reintroduction of an anti–PD-1 agent also seems to be a legitimate strategy, but, again, the data are limited by the low number of patients in the trial, and the profile of patients more at risk to experience late disease progression needs to be better defined,” he added.

“As a consequence, these results could not be translated to anti–PD-1 monotherapy, and further studies should be performed in that setting to ensure its safety,” Dr. Rousseau said. “MSI-H is also an agnostic biomarker, and this study was only conducted in metastatic colorectal cancer. Responses and duration of responses may be different in other tumor types, so I would be careful about considering these data outside of colorectal cancer.” 

DISCLOSURE: Dr. Rousseau reported financial relationships with Bayer, Roche, NeoPhore, Servier, Astellas, and Gilead.