A phase 1b multicenter study of trifluridine/tipiracil (FTD/TPI) in combination with irinotecan (IRI) in patients (pts) with metastatic or unresectable gastric and gastroesophageal adenocarcinoma (mGEC) after at least one line of treatment with a fluoropyrimidine and platinum (FP) containing regimen.

Abstract

e16006 Background: FTD/TPI, an antimetabolite, is approved for treatment of refractory mGEC. This study sought to determine whether the combination of FTD/TPI with IRI (“TASIRI”) was safe and effective in mGEC previously treated with FP. Methods: This investigator‐initiated, multicenter, open‐label, single-dose level, single‐arm phase 1b study enrolled pts with mGEC previously treated with at least one line of FP containing regimen. FTD/TPI was given at 25 mg/m2 twice daily on days 1 to 5 with 180 mg/m2 IRI on day 1 of a 14‐day cycle. The primary endpoint was progression-free survival at six months (mo) (PFS-6). The aim was to show an improvement of PFS-6 from 15% to at least 30% based on historical controls. Results: At the time of data-cutoff (03Feb2021), 23 pts were screened and ultimately 20 pts were treated. The study met its primary endpoint. With a median follow-up of 9.8 mo (range 0.7 – 17), 8 pts are still on treatment and 4 pts have died. PFS-6 is 53.9% (lower limit of 95% CI: 28%). Median PFS and overall survival are 6.9 mo and not reached, respectively. At the time of data-cutoff, data were available for 13 pts with measurable disease by RECIST criteria and at least 1 on-treatment scan. Of those, 11 had stable disease and 2 had progressive disease as best response (5 pts had tumor shrinkage < 30%), therefore the disease control rate was 84.6%. The most common any grade (G) treatment related adverse events (TRAE) were nausea (n = 14, 70%), diarrhea (n = 9, 45%), and fatigue (n = 8, 40%). G3-4 TRAE in > 5% of pts were anemia (17%) and neutropenia (9%). 2 serious TRAE were reported: G4 febrile neutropenia (n = 1) and G3 hypotension (n = 1). There was no G5 TRAE. Conclusions: The combination of TASIRI showed encouraging clinical activity with a meaningful improvement in PFS-6 compared to historic controls. TASIRI was well tolerated and no new safety signals were seen. TASIRI warrants further investigation for patients with refractory mGEC and limited treatment options. Updated results with longer follow-up will be presented at the meeting. Clinical trial information: NCT04074343.