S-1 (Teysuno) and gemcitabine in Caucasian patients with unresectable pancreatic adenocarcinoma.

Purpose: Gemcitabine has been standard of care in advanced pancreatic adenocarcinomas (PC) for almost two decades. Randomized, primarily Japanese, studies have shown promising efficacy when combined with S-1 (GemS-1); however, no data are published in Caucasian patients. We report the first study with a combination of GemS-1 in an unselected cohort of Caucasian PC patients.

Methods: In this observational cohort study, we analyzed efficacy and toxicity prospectively.

Results: From July 2012 to July 2014, 64 patients received at least one cycle of GemS-1. 16 patients started therapy with gemcitabine and capecitabine (GemCap) but switched to GemS-1 after median 3 cycles of GemCap due to toxicity (hand-foot syndrome). 48 patients received GemS-1 as initial therapy. For the complete cohort, median age was 68 years (range 44-80); 22 patients (34%) had locally advanced PC; 42 patients (66%) had metastatic disease. Five patients had received prior adjuvant therapy with gemcitabine and 9 pts had received prior first-line therapy. The most common adverse event was fatigue (86%), however, only grade 3 in 3%. Five patients (8%) developed febrile neutropenia. Median PFS was 8.1 (95% CI 6.9-9.0) months and median OS was 11.7 (95% CI 10.7-13.1) months in the whole GemS-1 population. In the 48 patients starting with GemS-1, median PFS was 7.7 (95% CI 6.7-8.9) months and median OS was 11.5 (95% CI 9.7-12.3) months.

Conclusions: The combination of gemcitabine and S-1 is safe and associated with promising efficacy in a Caucasian population; however, this needs to be confirmed in prospective clinical trials.