Study details
The patients studied were unselected for baseline tumor expression of programmed death–ligand 1, with 27% having expression of 1% or greater and 58% having expression below that threshold.
As of the data cutoff for the update, 47% of patients were still on treatment, Dr. Lenz reported at the symposium, sponsored by the American Gastroenterological Association, American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Surgical Oncology. The most common reason for stopping treatment was disease progression.
The investigator-assessed objective response rate, the primary endpoint, consisted of complete responses in 9% of patients and partial responses in 56%. (The rate as assessed by blinded independent central reviewers was 58%, consisting of complete responses in 18% and partial responses in 40%.)
“The high response rate was consistent among all evaluated subgroups,” Dr. Lenz noted, with no differences detected by presence or absence of Lynch syndrome and/or specific microsatellite-related mutations.
Median time to response was 2.6 months, and median duration of response was not reached. Median progression-free and overall survival were also not reached, but 15-month rates were 75% and 84%, respectively.
The rate of grade 3-4 treatment-related adverse events was 20%, and the rate of grade 3-4 serious treatment-related adverse events was 11%. Only 4% of patients discontinued treatment because of such events.
Ongoing trials may take immunotherapy even further in this patient population, according to Dr. Lenz. “We are all waiting for the treatments with the immunotherapy in combination with chemo and bevacizumab in first line. Will that change the efficacy and toxicity?” he elaborated. “You can imagine, in the MSI-H patients with the immunotherapy alone, we haven’t reached median progression-free and overall survival, so it may take a long time to get this data.”
Dr. Lenz reported receiving honoraria from Bayer, Boehringer Ingelheim, Merck Serono, and Roche; consulting or advising with Bayer, Merck Serono, Pfizer, and Roche; receiving travel expenses from Bayer, Merck Serono, and Roche. The trial was funded by Bristol-Myers Squibb. Dr. Sung reported that he had no relevant conflicts of interest.
SOURCE: Lenz H-J et al. 2020 GI Cancers Symposium, Abstract 11.