Cisplatin/5-FU (CF) +/- panitumumab (P) for patients (pts) with non-resectable, advanced, or metastatic esophageal squamous cell cancer (ESCC): An open-label, randomized AIO/TTD/BDGO/EORTC phase III trial (POWER).

Abstract

4011 Background: Most ESCC pts have advanced disease at time of diagnosis. Chemotherapy (CTX) is used to improve quality of life (QoL) and overall survival (OS), but still with limited impact. Prior studies suggested increased efficacy of EGFR antibodies (AB) combined with CF (Lorenzen, Ann Oncol 2009). Methods: This open-label, randomized (1:1), multicenter, multinational phase III included pts with non-resectable, advanced or metastatic ESCC (RECIST1.1), not radiochemotherapy (RCTX) eligible and ECOG 0-1. Previous CTX in metastatic setting, concurrent RCTX and exposure to EGFR-AB were excluded. Pts received CF (C 100 mg/m² d1 + F 1000 mg/m²/d, d1-4) or CFP (9 mg/kg d1) q3 weeks until disease progression. Due to more Gr3-4 SAEs in the first 60 Pts with CFP, C was reduced to 80mg/m²d1 Tumor assessment was performed q9 weeks. Primary objective was OS: superiority of CFP (9 months [mo]) over CF (6 mo) with 300 pts (90% power). Results: Between 6.2012-5.2015, 146/155 pts were randomized. After interim analysis for futility, the trial was stopped. 60(83%) of CFP and 55(79%) of CF pts had any AE, mostly diarrhea, hypokalemia, hypomagnesaemia, rash, and hand-foot syndrome. Main Gr≥3 AEs were low neutrophils 21/ 24% and anemia 13/16 % for CFP vs CF, respectively. Gr 3-4 skin reactions and rash were higher in CFP (10%) vs CF (0%). Overall, 51/72 (71%) of CFP and 36/70 (51%) of CF had SAE. Main SAE were dysphagia, acute kidney injury, diarrhea, fevers and febrile neutropenia in 6/6%, 7/4%, 7/3%, 3/6% and 6/1% for CFP vs CF, respectively. For all CFP vs CF pts, median OS was 9.4 vs. 10.2 mo (hazard ratio (HR) 1.17, 95%CI 0.79-1.75; P=0.43). For 56 pts treated with cisplatin 100mg/m²d1, OS was 9.4 vs. 12.9 mo (HR 1.83, 95 % CI 0.98-3.42; P=0.06). After C was reduced (80mg/m²), OS (85 pts) favored CFP vs CF, with 9.8 vs. 8.3 mo (HR 0.84, 95%CI 0.49-1.43; P=0.51). Median PFS for all CFP vs CF pts, was 5.3 vs. 5.8 mo. (HR 1.21, 95%CI 0.85-1.73; P=0.29) respectively. Conclusions: Addition of Panitumumab to CF provided no additional benefit to chemotherapy alone as first-line treatment of ESCC. Biomarker program is going on for further analyses. Clinical trial information: NCT1627379.