CHICAGO -- Patients who skipped maintenance therapy after a complete response to upfront treatment with a PD-1 inhibitor lived just as long as those who had 3 years of maintenance, data from a cohort study that compared nonsurgical colorectal cancer (CRC) options showed.
After more than 3 years of follow-up, patients who entered surveillance had a disease-free survival (DFS) of 96.4% versus 98.2% for patients who continued the PD-1 inhibitor. Every patient in the observation group was alive at 3 years, as were 98.4% of the patients who received maintenance pembrolizumab (Keytruda).
Patients who received maintenance therapy had a dramatically higher rate of immune-related adverse events (irAEs) during follow-up after clinical complete response (cCR), reported Xiaohang Gao, MD, of Sun Yat-sen University Cancer Center in Guangzhou, China, at the American Society of Clinical Oncology meeting.
"PD-1 inhibitor therapy induced cCR in 60% of patients with [deficient mismatch repair/microsatellite-high, dMMR/MSI-H] colorectal cancer, supporting non-operative management as a feasible organ-preservation strategy," she said. "After cCR, observation achieved comparable survival to maintenance with markedly less toxicity. These findings support treatment discontinuation after cCR with close surveillance, particularly during the first 2 years, pending prospective randomized validation."
