Results of the JAVELIN Gastric 100 phase 3 trial: avelumab maintenance following first-line (1L) chemotherapy (CTx) vs continuation of CTx for HER2− advanced gastric or gastroesophageal junction cancer (GC/GEJC).

Abstract

278 Background: We report the primary analysis of JAVELIN Gastric 100, which compared avelumab (anti–PD-L1) maintenance after 1L CTx vs continued CTx in patients (pts) with GC/GEJC. Methods: In this global, open-label, phase 3 trial (NCT02625610), eligible pts had previously untreated, unresectable, locally advanced/metastatic (LA/M) HER2− GC/GEJC. Pts without progressive disease (PD) after 12 weeks of 1L oxaliplatin/fluoropyrimidine induction were randomized 1:1 to avelumab 10 mg/kg Q2W switch maintenance or continued CTx, stratified by region (Asia vs non-Asia). Primary endpoint was overall survival (OS) post induction in all randomized or PD-L1+ (≥1% of tumor cells, 73-10 assay) pts. Results: 805 pts received induction CTx and 499 pts were randomized (avelumab, n = 249; CTx, n = 250). At data cutoff (Sep 13, 2019), minimum follow-up was 18 months. In the avelumab and CTx arms, median OS post induction/randomization was 10.4 months (95% CI 9.1-12.0) vs 10.9 months (95% CI 9.6-12.4), hazard ratio (HR) 0.91 (95% CI 0.74-1.11; p = 0.1779); 24-month OS rates were 22.1% (95% CI 16.8-28.0) vs 15.5% (95% CI 10.8-20.9), respectively. The HR for OS in PD-L1+ pts (n = 54) was 1.13 (95% CI 0.57-2.23). No OS trend was seen in Asian pts (n = 114; HR 0.90 [95% CI 0.59-1.36]) or other subgroups, except for a potential benefit with avelumab in pts with no metastatic sites at randomization (n = 60; HR 0.52 [95% CI 0.28-0.98]). Progression-free survival was similar between arms (HR 1.04 [95% CI 0.85-1.28]). In the avelumab vs CTx arms, objective response rates (post randomization only) were 13.3% (95% CI 9.3-18.1) vs 14.4% (95% CI 10.3-19.4), and 12-month rates for duration of response were 62.3% (95% CI 40.9-77.9) vs 28.4% (95% CI 13.2-45.7), respectively. Treatment-related adverse event rates (all grades/grade ≥3) were 61.3%/12.8% with avelumab and 77.3%/32.8% with CTx. Conclusions: Avelumab maintenance showed clinical activity and favorable safety vs continued CTx in pts with LA/M GE/GEJC; however, JAVELIN Gastric 100 did not meet its primary objective of demonstrating superior OS in the randomized or PD-L1+ population. Clinical trial information: NCT02625610.