According to the Zhongtong Finance APP, on June 25th, the National Medical Products Administration (NMPA) of China announced on its official website that Merck's (MRK.US) anti-PD-1 monoclonal antibody pembrolizumab has obtained approval for a new indication. According to Merck's press release, the approved indication for this drug is: used as first-line treatment for patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma verified by a fully validated tumor expression of PD-L1 (CPS≥1), in combination with trastuzumab, fluoropyrimidine, and platinum-containing chemotherapy. Thus far, the drug has been approved for 14 indications in China.

It is reported that the approval of pembrolizumab's new indication is based on data from the global Phase 3 clinical trial KEYNOTE-811. According to publicly available information from Merck, KEYNOTE-811 is a randomized, double-blind Phase 3 trial that enrolled approximately 732 patients. The dual primary endpoints were progress-free survival (PFS) and overall survival (OS) as independently assessed by a blinded central review based on RECIST v1.1 criteria. Secondary endpoints included objective response rate (ORR), duration of response, and safety.

In 2023, the mid-term analysis results published in the prestigious medical journal The Lancet showed that the KEYNOTE-811 study achieved one of its primary endpoints - significantly prolonging the PFS of patients. At a median follow-up time of about 28 months, the PFS of the pembrolizumab combination therapy group was 10 months, while the corresponding value for patients receiving only trastuzumab and chemotherapy was 8.1 months. Adding pembrolizumab reduced the risk of disease progression or death by 28%.

In May of this year, Merck announced that another major endpoint was reached in KEYNOTE-811, significantly prolonging the OS of patients. It is reported that this positive data is expected to support the conversion of accelerated approval of pembrolizumab by the FDA into full approval.

According to Dr. Li Zhengqing, Global Senior Vice President and President of China R&D Center at Merck, there have been few new treatment options in the first-line treatment of HER2-positive advanced gastric cancer in the past decade. Last year, pembrolizumab was approved in China for first-line treatment of locally advanced unresectable or metastatic HER2-negative gastric or gastroesophageal junction adenocarcinoma in combination with chemotherapy. This approval will further bring personalized treatment options for HER2-positive gastric cancer patients with PD-L1 expression (CPS≥1).