SAN FRANCISCO—The first phase 3 study in metastatic adenocarcinoma of the pancreas to report 3-year survival rates found overall survival (OS) to be sustained over time with nab-paclitaxel plus gemcitabine versus gemcitabine alone, investigators reported at the 2014 Gastrointestinal Cancers Symposium.
“These results may encourage efforts to build upon this well-tolerated backbone to further extend survival,” noted David Goldstein, MD, of the Department of Medical Oncology, Prince of Wales Hospital, New South Wales, Australia.
The multicenter study randomly assigned 861 patients 1:1 to receive nab-paclitaxel 125 mg/m2 plus gemcitabine 1,000 mg/m2 on days 1, 8, and 15 of a 28-day cycle (n = 431) or gemcitabine alone, given at 1,000 mg/m2 weekly for 7 weeks followed by 1 week of rest (cycle 1), followed by days 1, 8, and 15 of a 28-day cycle for cycle 2 and beyond (n = 430).
Previously, data from the phase 3 MPACT trial based on a database cut-off of September 17, 2012, at which time 80% of patients had died, found that nab-paclitaxel plus gemcitabine significantly improved median OS—the primary endpoint—compared with gemcitabine alone (8.5 vs. 6.7 months; hazard ratio [HR], 0.72; 95% CI: 0.617-0.835; P < 0.001). The combination also significantly improved progression-free survival (median, 5.5 vs. 3.7 months; HR, 0.69; 95% CI: 0.581-0.821; P < 0.001) and overall response rate (23% vs. 7%; P < 0.001). The 1-year survival rates for nab-paclitaxel plus gemcitabine compared with gemcitabine alone were 35% versus 22%.
In reporting the updated OS analysis (post hoc) from MPACT—for which data were collected through April 1, 2013—Dr. Goldstein noted that 88% of patients in the nab-paclitaxel plus gemcitabine and 92% in the gemcitabine alone arm had died.
Updated median OS was 8.7 months in the nab-paclitaxel plus gemcitabine arm versus 6.6 months in the gemcitabine alone arm (HR, 0.72; 95% CI: 0.620-0.825; P < 0.0001).
In the intent-to-treat population, the combination continued to result in a superior OS, “and the longer follow-up allowed an estimate of the 3-year survival rates,” he noted. One-year OS was 35% in the nab-paclitaxel plus gemcitabine arm versus 22% in the gemcitabine arm; 2-year OS was 10% versus 5%, and 3-year OS, 4% versus 0%.
The 2014 Gastrointestinal Cancers Symposium is sponsored by the American Gastroenterological Association (AGA) Institute, the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Surgical Oncology (SSO).