An exploration of trifluridine/tipiracil in combination with irinotecan in patients with pretreated advanced gastric cancer

Trifluridine/tipiracil (FTD/TPI) and irinotecan are treatment options for heavily pretreated patients with advanced gastric cancer, but their efficacies are limited. We investigated the combination of FTD/TPI and irinotecan for such patients.Patients who were refractory to fluoropyrimidine, platinum and taxane were enrolled into four cohorts (Level 1A/1B/2A/2B) and treated with irinotecan (100 [Level 1] or 125 [Level 2] mg/m2 on days 1 and 15) and FTD/TPI (35 mg/m2/dose, twice daily, on days 1-5 and 8-12 [Level A] or on days 1-5 and days 15-19 [Level B]) of a 28-day cycle. The primary endpoints were the maximum tolerated dose, dose-limiting toxicities (DLTs), and recommended phase II dose (RP2D); the secondary endpoint was the disease control rate (DCR).Eleven patients were enrolled: 2 at Level 1A, 3 at Level 1B, and 6 at Level 2B. DLTs occurred in 2/2 patients at Level 1A and 2/6 patients at Level 2B. Grade 3 or higher treatment-related adverse events were neutropenia (90.9%), leukopenia (54.5%), anemia (45.5%) and febrile neutropenia (18.2%). One patient at Level 2B achieved a partial response, and the DCR was 72.7% (95% CI, 39.0%-94.0%). The median progression-free survival and overall survival periods were 3.0 months (95% CI, 0.92-not reached) and 10.2 months (95% CI, 2.2-not reached), respectively.The RP2D of FTD/TPI combined with irinotecan was determined to be Level 1B; this level was associated with manageable hematologic toxicities and feasible non-hematologic toxicities. Further evaluation of the efficacy of RP2D treatment is necessary.