CheckMate-8HW Trial

Design — Phase 3, randomized; nivolumab (Opdivo) + ipilimumab (Yervoy) vs chemotherapy (1L) and vs nivolumab monotherapy, MSI-H/dMMR metastatic colorectal cancer (NCT04008030). (ASCO GI 2024/2025; ESMO 2025)

PFS (1L, primary vs chemo) — Median not reached vs 5.8 months (HR 0.21; 95% CI 0.14-0.32) — profound first-line benefit. (ASCO GI 2024/2025)

Overall survival — Descriptive analysis of NIVO+IPI vs NIVO monotherapy HR 0.61 (95% CI 0.45-0.83); medians not reached; OS still maturing. (ESMO 2025, Lonardi)

Safety — Grade >=3 adverse events 22.0% (NIVO+IPI) vs 14.0% (NIVO monotherapy); manageable and consistent with the checkpoint-inhibitor class; no new signals. (ASCO GI / ESMO)

Regulatory — FDA APPROVED — NIVO+IPI for MSI-H/dMMR unresectable/metastatic CRC; CheckMate-8HW supported the April 2025 first-line approval; not indicated for MSS disease. (FDA.gov)

Sponsor / Drug — Bristol Myers Squibb with Ono Pharmaceutical; nivolumab (Opdivo, anti-PD-1) + ipilimumab (Yervoy, anti-CTLA-4). (FDA label)

Compiled and reviewed by the KOL Pulse research team, led by Brian Shields, Founder, KOL Pulse. Last updated July 21, 2026.

Progression-Free Survival (PFS) — Primary Endpoint (NIVO+IPI vs. Chemo, 1L)

Median: not reached (NIVO + IPI, 95% CI 38.4-NE) vs. 5.8 months (chemotherapy, 95% CI 4.4-7.8). HR 0.21 (95% CI 0.14-0.32), P<0.0001 Median PFS not reached (95% CI: 38.4 to NE) with NIVO+IPI vs. 5.8 months (95% CI: 4.4-7.8) with chemotherapy — a 79% reduction in risk of progression or death. Analysis conducted in 255 patients with centrally confirmed MSI-H/dMMR status (of 303 based on local testing).

Overall Survival (OS)

Median: not reached (NIVO + IPI) vs. not reached (NIVO monotherapy). HR 0.61 (95% CI 0.45-0.83) ESMO 2025 (Sara Lonardi) descriptive OS analysis of NIVO+IPI vs. NIVO monotherapy across all lines in centrally confirmed MSI-H/dMMR mCRC: HR 0.61 (95% CI 0.45-0.83). Median OS not reached in either arm. OS data remain immature — 168 of ~243 expected deaths observed (~69% event maturity). The prespecified statistical boundary for significance at this interim was 0.0007 (hierarchical alpha allocation across co-primary endpoints), which was not crossed. Median follow-up 55.1 months (range 24.7-68.5). FDA approval (April 2025) was based on PFS alone; OS data were not available at time of interim PFS analysis per FDA approval document.

Safety & Tolerability

Grade ≥3 adverse events: 22.0% (nivo_ipi) vs. 14.0% (nivo_mono). Higher Grade ≥3 TRAE rate with NIVO+IPI than NIVO monotherapy but well-managed and consistent with established checkpoint inhibitor combinations. No new safety signals identified.

Clinical Implications

✅ New 1L SOC for MSI-H/dMMR mCRC. CheckMate-8HW establishes NIVO+IPI as a 1L standard for MSI-H/dMMR mCRC, building on KEYNOTE-177 (pembrolizumab monotherapy) benchmark. Superior PFS vs. both chemotherapy and NIVO alone. FDA approved April 2025. Choice between NIVO+IPI and pembrolizumab monotherapy in MSI-H mCRC balances efficacy depth vs. IR AE burden.

What is the CheckMate-8HW trial?

CheckMate-8HW (NCT04008030) is a Phase 3, randomized trial of nivolumab (Opdivo) plus ipilimumab (Yervoy) in microsatellite-instability-high or mismatch-repair-deficient (MSI-H/dMMR) metastatic colorectal cancer. It compares the combination against chemotherapy in the first-line setting and against nivolumab monotherapy, and was sponsored by Bristol Myers Squibb with Ono Pharmaceutical.

What were the CheckMate-8HW results?

In the first-line setting, nivolumab plus ipilimumab dramatically improved progression-free survival versus chemotherapy, with median PFS not reached versus 5.8 months (HR 0.21; 95% CI 0.14-0.32). A descriptive comparison of the combination versus nivolumab monotherapy showed an overall-survival HR of 0.61 (95% CI 0.45-0.83), with medians not reached and overall survival still maturing.

Is nivolumab plus ipilimumab FDA approved for MSI-H/dMMR colorectal cancer?

Yes. Nivolumab (Opdivo) plus ipilimumab (Yervoy) is FDA approved for MSI-H/dMMR unresectable or metastatic colorectal cancer, with CheckMate-8HW supporting the April 2025 first-line approval of the combination. It is indicated specifically for MSI-H/dMMR disease and is not indicated for microsatellite-stable (MSS) colorectal cancer.

How does CheckMate-8HW change first-line treatment of MSI-H/dMMR colorectal cancer?

CheckMate-8HW establishes nivolumab plus ipilimumab as a first-line standard for MSI-H/dMMR metastatic colorectal cancer, building on the pembrolizumab-monotherapy benchmark from KEYNOTE-177. The combination showed superior progression-free survival versus both chemotherapy and nivolumab alone, giving clinicians a highly active dual-checkpoint option for this biomarker-selected population.

What are the safety considerations with nivolumab plus ipilimumab in CheckMate-8HW?

Grade 3 or higher adverse events occurred in about 22.0% of patients on nivolumab plus ipilimumab versus 14.0% on nivolumab monotherapy — a higher rate with the combination but consistent with the established dual-checkpoint profile and considered manageable, with no new safety signals identified. Immune-related adverse events require standard monitoring and management.