Study details
Patients in GAMMA-1 were randomized evenly to receive the mFOLFOX-6 regimen plus either placebo or andecaliximab given intravenously every 2 weeks.
Median overall survival, the primary outcome, was 12.5 months with the antibody and 11.8 months with placebo, a nonsignificant difference (hazard ratio, 0.93; P = .56), Dr. Shah reported at the symposium, which is sponsored by the American Gastroenterological Association, the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Surgical Oncology.
However, exploratory analyses showed benefit increased with quartile of age, and the difference in overall survival was significant for those 65 years and older at 13.9 months versus 10.5 months (HR, 0.64; P = .029).
The pattern was similar for progression-free survival, with only a trend among all patients (7.5 vs. 7.1 months; HR, 0.84; P = .10) but a significant reduction in risk for the older subgroup (8.7 vs 5.6 months; HR, 0.5; P less than .001).
Overall response rate was better with andecaliximab than with placebo in the entire trial population (51% vs. 41%; odds ratio, 1.47; P = .049). The rate of complete response was 8.3% and 4.7%, respectively.
“There were no meaningful differences in the safety profile of andecaliximab versus placebo in the groups treated,” Dr. Shah said. Rates and types of treatment-emergent adverse events of any grade and of grade 3 or higher were similar, with gastrointestinal and hematologic events predominating.
“We were intrigued with this phenomenon by age,” he said, and the investigators therefore assessed factors differing by age. “We looked at chemotherapy treatment and toxicity, things like that, and it didn’t appear that we could find any factor that was really associated. We did find that older patients actually received more treatment, but that’s likely because they had somewhat of a benefit with andecaliximab.”
Dr. Shah reported receiving research funding from Boston Biomedical, Gilead Sciences, Merck, and Oncolys BioPharma. The trial was sponsored by Gilead Sciences.
SOURCE: Shah MA et al. GI Cancers Symposium 2019, Abstract 4.
This article was updated 1/24/19.