Colorectal Cancer treatment landscape

First-line therapy of pembrolizumab versus standard of care (SOC) in microsatellite instability-high/mismatch repair deficient metastatic colorectal cancer: The phase III, KEYNOTE-177 study.

Abstract No : LBA4

Abstract Type : Plenary Session, Sun, 1:00 PM-4:00 PM

Indication : Colorectal Cancer

Intervention : pembrolizumab versus standard of care (SOC)

Company : Merck

Technology : Monoclonal antibody


At data cutoff, 153 pts were randomized to pembro and 154 to chemo. Median (range) study follow-up was 28.4 mo (0.2-48.3) with pembro vs 27.2 mo (0.8-46.6) with chemo. Pembro was superior to chemo for PFS (median 16.5 mo vs 8.2 mo; HR 0.60; 95% CI, 0.45-0.80; P=0.0002). The 12- and 24-mo PFS rates were 55.3% and 48.3% with pembro vs 37.3% and 18.6% with chemo. Confirmed ORR was 43.8% vs 33.1%; median (range) duration of response was not reached (2.3+ to 41.4+) with pembro vs 10.6 mo (2.8 to 37.5+) with chemo. Grade 3-5 treatment-related adverse event (AE) rates were 22% vs 66% for pembro vs chemo. One pt in the chemo arm died due to a treatment-related AE.


Pembro provided a clinically meaningful and statistically significant improvement in PFS versus chemo as first-line therapy for pts with MSI-H/dMMR mCRC, with fewer treatment-related AEs observed and should be the new standard of care for these pts.


Such an outstanding data of KEYNOTE-177 will place Pembrolizumab as the new standard of care as first-line therapy in patients with microsatellite instability-high (MSI-H) metastatic colorectal cancer. Doubling of PFS with Pembro over chemo with limited toxicity is compelling data.

Refer to Colorectal Cancer Market report for detailed Insights.