CheckMate 649: A randomized, multicenter, open-label, phase III study of nivolumab (NIVO) + ipilimumab (IPI) or nivo + chemotherapy (CTX) versus CTX alone in patients with previously untreated advanced (Adv) gastric (G) or gastroesophageal junction (GEJ) cancer.

TPS192 Background: Pts with adv G/GEJ cancer have an OS of ≈ 1 y, indicating an unmet medical need for new first-line treatments. Expression of PD-L1 is observed in up to 40% of pts with G/GEJ cancer and is associated with poor prognosis. In the randomized phase 3 ATTRACTION-2 study, NIVO demonstrated superior overall survival vs placebo with a 38% reduction of the risk of death (median OS, 5.3 vs 4.1 mo; HR, 0.62 P< 0.0001) and increased the OS rate at 12 mo (27% vs 12%; Boku N et al ESMO 2017) in pts with adv CTX-R (≥ 2 lines) G/GEJ cancer. In the phase 1/2 CheckMate-032 study in pts with CTX-R G/GEJ/esophageal cancer (79% ≥ 2 prior Tx lines), NIVO 1 mg/kg + IPI 3 mg/kg had a manageable safety profile and resulted in 24% ORR (40% ORR in pts with PD-L1+ tumors), a median OS of 6.9 mo, and a 35% OS rate at 12 mo (Janjigian Y et al ASCO 2017). In the phase 1 CheckMate-012 trial, NIVO + CTX had clinical activity and manageable safety in pts with NSCLC (Rizvi NA et al J Clin Oncol 2016). These positive results support investigation of NIVO, NIVO + IPI, and NIVO + CTX in earlier lines of treatment for G/GEJ cancer. The open-label, phase 3 CheckMate 649 trial will evaluate NIVO + IPI and NIVO + CTX vs CTX alone as first-line treatment for pts with adv G/GEJ cancer (NCT02872116). Methods: 1266 pts aged ≥ 18 y with untreated, inoperable adv/metastatic G/GEJ cancer (histologically confirmed adenocarcinoma) regardless of PD-L1 status will be randomized to receive either NIVO + IPI, NIVO + CTX (capecitabine/oxaliplatin [XELOX] or fluorouracil/leucovorin/oxaliplatin [FOLFOX]), or investigator choice of XELOX or FOLFOX. Tumor tissue for determination of PD-L1 status (Dako assay) must be provided from ≤ 6 mo before study treatment. No prior systemic treatment, including HER2 inhibitors, are allowed. Pts with known HER2+ status, suspected autoimmune disease, grade > 1 peripheral neuropathy, or active infection are excluded. Primary endpoint is OS in pts with PD-L1+ (≥ 1%) tumors. Other endpoints include OS in all pts; PFS and time to symptom deterioration in all pts and in pts with PD-L1+ tumors; and safety. Clinical trial information: NCT02872116.