Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the Phase 3 KEYNOTE-811 trial evaluating KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with trastuzumab and fluoropyrimidine- and platinum-containing chemotherapy met its dual primary endpoint of overall survival (OS) for the first-line treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive locally advanced unresectable or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma.
Based on results from KEYNOTE-811, KEYTRUDA is approved in combination with trastuzumab and fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-approved test. This indication is approved by the U.S. Food and Drug Administration (FDA) under accelerated approval regulations based on the objective response rate (ORR) and durability of response demonstrated at an earlier analysis. Continued approval of this indication may be contingent upon verification and description of clinical benefit at the final analysis of the KEYNOTE-811 study.
In the final analysis of this trial, KEYTRUDA in combination with trastuzumab and chemotherapy demonstrated a statistically significant and clinically meaningful improvement in OS compared to placebo in combination with trastuzumab and chemotherapy in the intention-to-treat (ITT) study population, with the greatest benefit observed in patients whose tumors expressed PD-L1 (CPS ≥1). The safety profile of KEYTRUDA in this trial was consistent with that observed in previously reported studies; no new safety signals were identified. Results will be presented at an upcoming medical meeting and shared with regulatory authorities worldwide.
“Patients diagnosed with advanced gastric cancer often face a poor prognosis, underscoring the need for treatment options that have the potential to extend patients’ lives,” said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. “These overall survival results from KEYNOTE-811 are encouraging and build on the positive progression-free survival, overall response rate and duration of response data from this study.”
As previously announced, at an earlier interim analysis, KEYNOTE-811 met the other dual primary endpoint of progression-free survival (PFS) and these results were presented at the European Society for Medical Oncology (ESMO) Congress 2023.
In the U.S., KEYTRUDA is also approved for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or GEJ adenocarcinoma, based on results from KEYNOTE-859.
Merck has an extensive clinical development program evaluating KEYTRUDA in gastrointestinal cancers and is continuing to study KEYTRUDA for multiple uses in gastric, hepatobiliary, esophageal and colorectal cancers.
About KEYNOTE-811
KEYNOTE-811 is a randomized, double-blind Phase 3 trial (ClinicalTrials.gov, NCT03615326) evaluating KEYTRUDA in combination with trastuzumab and chemotherapy for the first-line treatment of locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma. The dual primary endpoints are PFS per RECIST v1.1 as assessed by blinded independent central review and OS. Secondary endpoints include ORR, duration of response and safety. The trial enrolled 698 patients who were randomized to receive KEYTRUDA (200 mg every three weeks) in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy (investigator’s choice of 5-fluorouracil plus cisplatin or capecitabine plus oxaliplatin), or placebo in combination with trastuzumab and chemotherapy.
About gastric cancer
Gastric (stomach) cancer tends to develop slowly over many years and rarely causes early symptoms, resulting in most cases going undetected until an advanced stage.More than 70% of patients with gastric cancer develop advanced-stage disease. Most gastric cancers are adenocarcinomas (about 90-95%), which develop from cells in the innermost lining of the stomach (known as the mucosa). Gastric cancer is the fifth most diagnosed cancer and the fifth leading cause of cancer death worldwide, with approximately 969,000 patients diagnosed and 660,000 deaths from the disease globally in 2022.In the U.S., it is estimated there will be approximately 26,890 patients diagnosed with gastric cancer and 10,880 deaths from the disease in 2024. The five-year survival rate for patients diagnosed with gastric cancer at an advanced stage is only 7%.
About KEYTRUDA® (pembrolizumab) injection, 100 mg
KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the body’s immune system to help detect and fight tumor cells. KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD- L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.
Merck has the industry’s largest immuno-oncology clinical research program. There are currently more than 1,600 trials studying KEYTRUDA across a wide variety of cancers and treatment settings. The KEYTRUDA clinical program seeks to understand the role of KEYTRUDA across cancers and the factors that may predict a patient’s likelihood of benefitting from treatment with KEYTRUDA, including exploring several different biomarkers.
Selected Important Safety Information for KEYTRUDA
Gastric Cancer
KEYTRUDA, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-approved test.
This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval of this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.
KEYTRUDA, in combination with fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or gastroesophageal junction (GEJ) adenocarcinoma.
