Pembrolizumab Approval Expansion: MSI-High Colorectal and Triple-Negative Breast Cancer

FDA Approval Announcement

• August 31, 2021

On August 25, 2021, MSD announced FDA approval of pembrolizumab for two additional cancer indications: MSI-high unresectable colorectal cancer and PD-L1+ triple-negative breast cancer.

MSI-High Colorectal Cancer Approval

Evidence Base: KEYNOTE-177 Phase III trial (n=307 untreated, unresectable, MSI-high colorectal cancer)

Efficacy Results:

• Significant progression-free survival improvement with pembrolizumab vs chemotherapy
• 40% disease progression/mortality risk reduction

Triple-Negative Breast Cancer Approval

Evidence Base: KEYNOTE-355 Phase III trial (n=847; n=323 PD-L1+)

Trial Design: Treatment-naive recurrent/locally advanced triple-negative breast cancer

Efficacy Results:

• Significant progression-free survival improvement with pembrolizumab + chemotherapy vs placebo + chemotherapy
• 35% disease progression/mortality risk reduction in PD-L1+ subgroup

Clinical Significance

These approvals expand pembrolizumab indication scope to early-stage disease settings and biomarker-defined populations, supporting earlier intervention in immune-responsive cancers.

Data Source

MSD Product Announcement: https://www.msd.co.jp/newsroom/msd-archive/2021/product_news_0825.xhtml

Medical Supporter was formerly certified as an international medical visa guarantor by Japan's Ministry of Foreign Affairs and the Ministry of Economy, Trade and Industry (B-066).

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