Approval based on progression-free survival benefit demonstrated in Phase 3 KEYNOTE-811 trial

KEYTRUDA is the first immunotherapy approved in the EU for the first-line treatment of this patient population

RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the European Commission (EC) has approved KEYTRUDA, Merck’s anti-PD-1 therapy, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma in adults whose tumors express PD-L1 (Combined Positive Score [CPS] ≥1).

This approval by the EC follows the positive recommendation from the Committee for Medicinal Products for Human Use received in July 2023 and was based on results from the Phase 3 KEYNOTE-811 trial. In the study, KEYTRUDA plus trastuzumab and chemotherapy significantly improved progression-free survival (PFS), and objective response rate (ORR), compared to trastuzumab and chemotherapy alone in this patient population. In the study, more than 80% of patients had tumors that were PD-L1 positive.

There was a trend toward improvement in overall survival (OS), the trial’s other primary endpoint, in the ITT population for patients who received the KEYTRUDA combination versus placebo in combination with trastuzumab and chemotherapy; however, these results did not meet statistical significance per the pre-specified statistical analysis plan. OS analysis for this trial is ongoing.

Results from KEYNOTE-811 will be presented at the upcoming 2023 European Society for Medical Oncology (ESMO) Annual Meeting.

“Patients in the EU diagnosed with HER2-positive advanced gastric cancer face an aggressive disease associated with a poor prognosis, underscoring the need for additional first-line treatment options for these patients,” said Dr. Scot Ebbinghaus, vice president, global clinical development, Merck Research Laboratories. “With today’s approval of KEYTRUDA, we’re proud that patients whose tumors express PD-L1 with a combined positive score ≥1 and healthcare providers in the EU will have an option that includes immunotherapy for this difficult-to-treat disease.”

This approval allows marketing of this KEYTRUDA regimen in all 27 European Union (EU) member states plus Iceland, Lichtenstein, Norway and Northern Ireland.

In May 2021, KEYTRUDA was approved in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma in the U.S. This indication was approved by the FDA under accelerated approval based on ORR data from KEYNOTE-811, and continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials. Merck is working with the FDA to update this indication to patients whose tumors are PD-L1 positive.

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 an estimated 732 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 patients presenting with advanced stage disease. Overall, more than 70% of patients with gastric cancer develop advanced-stage disease. Most gastric cancers are adenocarcinomas (about 90% to 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 fourth leading cause of cancer death worldwide, with approximately 1.1 million patients diagnosed and 768,000 patient deaths from the disease globally in 2020.In Europe, it is estimated that there were approximately 136,000 patients diagnosed with gastric cancer and 97,000 patient deaths from the disease in 2020. The five-year survival rate for patients diagnosed with gastric cancer at an advanced stage is only 6%.

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 KEYTRUDA® (pembrolizumab) Indications in the U.S.

Gastric Cancer

KEYTRUDA, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma.

This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

See additional selected KEYTRUDA indications in the U.S. after the Selected Important Safety Information.

Selected Important Safety Information for KEYTRUDA

Severe and Fatal Immune-Mediated Adverse Reactions

KEYTRUDA is a monoclonal antibody that belongs to a class of drugs that bind to either the PD-1 or the PD-L1, blocking the PD-1/PD-L1 pathway, thereby removing inhibition of the immune response, potentially breaking peripheral tolerance and inducing immune-mediated adverse reactions. Immune-mediated adverse reactions, which may be severe or fatal, can occur in any organ system or tissue, can affect more than one body system simultaneously, and can occur at any time after starting treatment or after discontinuation of treatment. Important immune-mediated adverse reactions listed here may not include all possible severe and fatal immune-mediated adverse reactions.

Monitor patients closely for symptoms and signs that may be clinical manifestations of underlying immune-mediated adverse reactions. Early identification and management are essential to ensure safe use of anti–PD-1/PD-L1 treatments. Evaluate liver enzymes, creatinine, and thyroid function at baseline and periodically during treatment. For patients with TNBC treated with KEYTRUDA in the neoadjuvant setting, monitor blood cortisol at baseline, prior to surgery, and as clinically indicated. In cases of suspected immune-mediated adverse reactions, initiate appropriate workup to exclude alternative etiologies, including infection. Institute medical management promptly, including specialty consultation as appropriate.

Withhold or permanently discontinue KEYTRUDA depending on severity of the immune-mediated adverse reaction. In general, if KEYTRUDA requires interruption or discontinuation, administer systemic corticosteroid therapy (1 to 2 mg/kg/day prednisone or equivalent) until improvement to Grade 1 or less. Upon improvement to Grade 1 or less, initiate corticosteroid taper and continue to taper over at least 1 month. Consider administration of other systemic immunosuppressants in patients whose adverse reactions are not controlled with corticosteroid therapy.

Immune-Mediated Pneumonitis

KEYTRUDA can cause immune-mediated pneumonitis. The incidence is higher in patients who have received prior thoracic radiation. Immune-mediated pneumonitis occurred in 3.4% (94/2799) of patients receiving KEYTRUDA, including fatal (0.1%), Grade 4 (0.3%), Grade 3 (0.9%), and Grade 2 (1.3%) reactions. Systemic corticosteroids were required in 67% (63/94) of patients. Pneumonitis led to permanent discontinuation of KEYTRUDA in 1.3% (36) and withholding in 0.9% (26) of patients. All patients who were withheld reinitiated KEYTRUDA after symptom improvement; of these, 23% had recurrence. Pneumonitis resolved in 59% of the 94 patients.

Pneumonitis occurred in 8% (31/389) of adult patients with cHL receiving KEYTRUDA as a single agent, including Grades 3-4 in 2.3% of patients. Patients received high-dose corticosteroids for a median duration of 10 days (range: 2 days to 53 months). Pneumonitis rates were similar in patients with and without prior thoracic radiation. Pneumonitis led to discontinuation of KEYTRUDA in 5.4% (21) of patients. Of the patients who developed pneumonitis, 42% interrupted KEYTRUDA, 68% discontinued KEYTRUDA, and 77% had resolution.

Pneumonitis occurred in 7% (41/580) of adult patients with resected NSCLC who received KEYTRUDA as a single agent for adjuvant treatment of NSCLC, including fatal (0.2%), Grade 4 (0.3%), and Grade 3 (1%) adverse reactions. Patients received high-dose corticosteroids for a median duration of 10 days (range: 1 day to 2.3 months). Pneumonitis led to discontinuation of KEYTRUDA in 26 (4.5%) of patients. Of the patients who developed pneumonitis, 54% interrupted KEYTRUDA, 63% discontinued KEYTRUDA, and 71% had resolution.

Immune-Mediated Colitis

KEYTRUDA can cause immune-mediated colitis, which may present with diarrhea. Cytomegalovirus infection/reactivation has been reported in patients with corticosteroid-refractory immune-mediated colitis. In cases of corticosteroid-refractory colitis, consider repeating infectious workup to exclude alternative etiologies. Immune-mediated colitis occurred in 1.7% (48/2799) of patients receiving KEYTRUDA, including Grade 4 (