The relationship between antitumor effects and relative dose intensity of gemcitabine plus nab-paclitaxel for unresectable pancreatic cancer.

Abstract

419 Background: Gemcitabine plus nab-paclitaxel (GEM+nab-PTX) is the standard first-line chemotherapy for unresectable pancreatic cancer, but the relationship between antitumor effects and relative dose intensity (RDI) remains unclear. Methods: A retrospective analysis of pancreatic cancer patients treated with GEM+nab-PTX as first-line chemotherapy between January 2015 and July 2016 at Cancer Institute Hospital of JFCR was performed. The RDI of GEM+nab-PTX was calculated as the delivered dose intensity divided by standard dose intensity. The patients were divided into two groups by median RDI. Kaplan Meier curves were constructed in order to analyze progression-free survival (PFS), time to treatment failure (TTF) and overall survival (OS), and differences between the two groups were compared with a log-rank test. Results: A total of 102 patients (52 male, a median age of 66 years) were enrolled. Eighty-two (80%) had metastatic disease. The best overall response was partial response in 30 (29%) and stable disease in 53 (52%). The median PFS, TTF and OS of the total cohort was 188 days (95% confidence interval: CI, 162 to 224), 161 days (95% CI, 146 to 183) and 369 days (95% CI, 309 to 440) respectively. The median RDI were 77% (range 30-100). In the RDI < 77% (n = 50) and the RDI ≥ 77% (n = 52) groups, the median PFS was 196 and 183 days (p = 0.33), the median TTF was 162 and 160 days (p = 0.186) and the median OS were 410 and 312 days (p = 0.10), respectively. Twenty-nine (28%) were eventually administered GEM+nab-PTX biweekly. The median RDI of biweekly regimen was 63% (range 29-86). The TTF of biweekly regimen and original weekly regimen was 196 and 160 days (p = 0.004) respectively. Conclusions: RDI is not a significant predictor of antitumor effects, and an appropriate dose reduction and extension of dosing interval may be permitted in pancreatic cancer patients treated with GEM+nab-PTX.