Background: We assessed RAM or MER plus standard of care GEM+CIS as first-line treatment for BTC. Methods: Patients (pts) with BTC, ECOG PS 0/1, and measurable disease were randomized 2:1:2:1 to oral MER 80 mg QD, oral PL QD, IV RAM 8 mg/kg days 1 and 8 Q3W or IV PL days 1 and 8 Q3W. Pts also received up to 8 cycles IV GEM 1000 mg/m² + CIS 25 mg/m² days 1 and 8 Q3W. RAM, MER, or PL could continue until disease progression. Primary endpoint: progression-free survival (PFS). Secondary endpoints: overall survival (OS), objective response rate (ORR), and safety. PFS and hazard ratios (HRs) were compared using stratified log-rank tests and Cox regression models, respectively. NCT02711553. Results: 309 pts were randomized to RAM (106), MER (102), or pooled PL (101). More pts in the RAM (54.7%) and MER (49.0%) groups had baseline ECOG PS 1 vs PL (38.6%). Efficacy endpoints are in Table. Fewer pts received post-discontinuation systemic therapy in the RAM group (RAM 37.5%, MER 50.0%, PL 52.0%). The most common grade ≥3 treatment-emergent adverse events were: RAM vs PL: neutropenia (49.0% vs 33.0%), thrombocytopenia (34.6% vs 17.0%), and anemia (26.9% vs 19.0%); MER vs PL: neutropenia (47.1% vs 33.0%), thrombocytopenia (18.6% vs 17.0%), and alanine aminotransferase increased (10.8% vs 5.0%). Conclusions: PFS, OS, and ORR were not improved with the addition of RAM or MER to GEM+CIS. Treatment was well tolerated, with safety profiles consistent with known profiles for RAM, MER, and GEM+CIS. Translational studies are ongoing. Clinical trial information: NCT02711553.