Merck Announces Positive Phase 3 KEYNOTE-177 Results for Pembrolizumab in First-Line MSI-H/dMMR Metastatic Colorectal Cancer at ASCO20

KENILWORTH, N.J., June 18, 2020 /PRNewswire/ -- MSD (MSD is the business name of Merck & Co., Inc., Kenilworth, New Jersey, USA)May 28The results of the Phase III clinical trial KEYNOTE-177 were announced for the first time. This study aimed to evaluate the efficacy of Merck’s PD-1 inhibitor pembrolizumab as a first-line treatment for patients with unresectable or metastatic colorectal cancer characterized by high microsatellite instability (MSI-H) or mismatch repair deficiency (dMMR).

Colorectal cancer is one of the most prevalent malignant tumors in China. According to the latest statistical data from the National Cancer Center, in 2015, the incidence and mortality rates of colorectal cancer ranked third and fifth, respectively, among all malignant tumors in China, with 388,000 new cases and 187,000 deaths.^[1]Microsatellite instability (MSI) refers to the erroneous repetition and accumulation of microsatellites (short repetitive DNA sequences) during genetic replication in the DNA of certain cells (e.g., tumor cells). This phenomenon may result from a defect in the ability to repair DNA replication errors during cell division, a condition also known as mismatch repair deficiency (dMMR). The incidence of high microsatellite instability (MSI-H) varies significantly across different cancer types, at approximately 12-15% of colorectal cancers exhibit microsatellite instability-high (MSI-H) or mismatch repair deficiency (dMMR)^[2]。

Dr. Roy Baynes, Senior Vice President of Global Clinical Research and Head of Development, Chief Medical Officer at MSD Laboratories, stated, “Patients with MSI-H colorectal cancer require novel first-line treatment regimens capable of delivering durable disease remission and sustained efficacy, yet this need has remained unmet. We are deeply grateful for the opportunity to present these trial results, which have the potential to transform clinical practice, at this year’s ASCO Plenary Session.”

The results of the KEYNOTE-177 study (Abstract #LBA4) were announced on Sunday, May 31, 2020, during the plenary session and press conference of the American Society of Clinical Oncology (ASCO) Virtual Scientific Program. At this conference, Merck Sharp & Dohme (MSD) presented more than 80 research abstracts covering its oncology products and investigational pipeline, spanning nearly 20 types of solid tumors and hematologic malignancies.

To date, the indications for pembrolizumab approved by the National Medical Products Administration (NMPA) of China include: treatment of unresectable or metastatic melanoma after failure of first-line therapy; first-line treatment of metastatic non-squamous non-small cell lung cancer (NSCLC) in combination with pemetrexed and platinum-based chemotherapy for patients with negative EGFR/ALK gene mutations; first-line monotherapy for locally advanced or metastatic NSCLC in patients with PD-L1 positive expression (TPS ≥ 1%) as assessed by an NMPA-approved test and negative EGFR/ALK gene mutations; and first-line treatment of metastatic squamous NSCLC in combination with carboplatin and paclitaxel. The indication for pembrolizumab in the treatment of colorectal cancer has not yet been approved by the NMPA.

[1] Zheng Rongshou, Sun Kexin, Zhang Siwei, et al. Analysis of the epidemiology of malignant tumors in China in 2015. Chinese Journal of Oncology [J], 2019, 41(1)

[2] Yuan Ying. Chinese expert consensus on microsatellite instability testing in colorectal cancer and other related solid tumors[J]. Journal of Practical Oncology, 2019(5)