On April 27, 2025 Merck (NYSE: MRK), known as MSD outside of the United States and Canada, reported results from the Phase 3 KEYNOTE-689 trial evaluating KEYTRUDA (pembrolizumab), Merck’s anti-PD-1 therapy, as a perioperative treatment regimen for patients with stage III or IVA, resected, locally advanced head and neck squamous cell carcinoma (LA-HNSCC) (Press release, Merck & Co, APR 27, 2025, View Source [SID1234652189]). Results at the first interim analysis of the trial showed KEYTRUDA significantly improved event-free survival (EFS) as part of a perioperative treatment regimen with adjuvant standard of care (SOC) radiotherapy with or without cisplatin compared to adjuvant standard of care (SOC) radiotherapy with or without cisplatin alone in patients with resectable LA-HNSCC. These data are being presented for the first time today during a Plenary Session at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2025 (Abstract #CT001) and were selected for the AACR (Free AACR Whitepaper) press program.
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After a median follow-up of 38.3 months (range, 9.0-66.5), treatment with KEYTRUDA before surgery (neoadjuvant), then continued in combination with standard of care radiotherapy (with or without cisplatin) after surgery followed by KEYTRUDA alone (adjuvant), reduced the risk of EFS events by 34% (HR=0.66 [95% CI, 0.49-0.88]; p=.0022) in the combined positive score (CPS) ≥10 population, by 30% (HR=0.70 [95% CI, 0.55-0.89; p=.0014) in the CPS ≥1 population and by 27% (HR=0.73 [95% CI 0.58-0.92]; p=.0041) in the intent-to-treat (ITT) population, compared to adjuvant radiotherapy (with or without cisplatin) alone in the ITT population. Among the CPS ≥10 population, median EFS was 59.7 months in the KEYTRUDA plus SOC group (95% CI, 41.1-not reached) versus 26.9 months (95% CI, 18.3-51.5) in the SOC group. Among the CPS ≥1 population, median EFS was 59.7 months (95% CI, 37.9-not reached) in the KEYTRUDA plus SOC group versus 29.6 months (95% CI, 19.5-41.9) in the SOC group. In the ITT population, median EFS was 51.8 months (95% CI, 37.5-not reached) in the KEYTRUDA plus SOC group versus 30.4 months (95% CI, 21.8-50.1) in the SOC group. The safety profile of KEYTRUDA was consistent with that observed in previously reported studies; no new safety signals were identified.
"As the first positive trial in over two decades for patients with resectable, locally advanced head and neck squamous cell carcinoma, the presentation of these landmark results marks an important moment for these patients and those who care for them," said Dr. Ravindra Uppaluri, the study’s co-principal investigator, director of Head and Neck Surgical Oncology, Brigham and Women’s Hospital and Dana-Farber Cancer Institute. "KEYNOTE-689 represents a meaningful development with a potential to provide an option that helps certain patients with LA-HNSCC reduce the risk of recurrence and disease progression earlier in their treatment journey."
"The addition of immunotherapy using KEYTRUDA to standard of care surgery and adjuvant (chemo)radiotherapy resulted in a significant reduction in the risk of event-free survival events by 27%, compared with standard of care therapy alone," said study co-principal investigator Dr. Douglas Adkins, Professor, Division of Oncology, Washington University School of Medicine in St. Louis. "These results are notable as they mark the first time an anti-PD-1 therapy has demonstrated a statistically significant and clinically meaningful improvement in event-free survival in the neoadjuvant and adjuvant setting in earlier stages of head and neck squamous cell carcinoma."
The study also showed a statistically significant improvement in major pathological response (mPR) rate, a key secondary endpoint, in patients with CPS ≥10 (difference in mPR rates: 13.7% [95% CI, 9.7-18.7]; p<0.00001), CPS ≥1 (9.8% [95% CI, 7.0-13.3]; p<0.00001) and in the ITT population (9.3% [95% CI, 6.7–12.8, P<.00001), compared to adjuvant radiotherapy alone.
A trend toward improvement in overall survival (OS), another key secondary endpoint, was observed in patients with CPS ≥10 (HR=0.72 [95% CI, 0.52-0.98]) at the time of this interim analysis for the KEYTRUDA plus standard of care regimen versus standard of care alone. The OS results did not reach statistical significance at the time of this interim analysis. Due to the statistical testing hierarchy, formal testing was not performed in the CPS ≥1 and ITT populations. OS will be evaluated at the next interim analysis.
"As the 12th positive pivotal trial for a KEYTRUDA-based regimen in earlier-stage cancers, the results from KEYNOTE-689 are a testament to our commitment to address an unmet need in this important area of research," said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. "These compelling results illustrate the potential of this regimen to change the landscape of care for certain patients facing this challenging disease. We are working with the FDA and other global authorities to bring this new option to patients as quickly as possible."
A supplemental Biologics License Application (sBLA) for KEYTRUDA based on data from KEYNOTE-689 is under priority review with the U.S. Food and Drug Administration (FDA), with a Prescription Drug User Fee Act (PDUFA), or target action, date of June 23, 2025.
KEYTRUDA is currently approved as monotherapy and in combination regimens for appropriate patients with metastatic or unresectable, recurrent HNSCC in the U.S., Europe, China, Japan and other countries around the world. For more information, please see the "Selected KEYTRUDA (pembrolizumab) Indications in the U.S." section below.
Study design and additional data from KEYNOTE-689
KEYNOTE-689 is a randomized, active-controlled, open-label Phase 3 trial (ClinicalTrials.gov, NCT03765918) evaluating KEYTRUDA as neoadjuvant treatment and KEYTRUDA in combination with standard of care radiotherapy (with or without cisplatin) as adjuvant treatment in treatment-naïve patients with newly diagnosed, stage III or IVA resectable, locally advanced head and neck squamous cell carcinoma (LA-HNSCC). Efficacy outcomes are classified by programmed cell death ligand 1 (PD-L1) combined positive score (CPS) status. The primary endpoint is EFS, which is defined as the time from randomization to the first occurrence of radiographic disease progression; local or distant progression or recurrence; or death due to any cause. The secondary endpoints include OS, mPR, pathological complete response and safety. The study enrolled 714 patients who were randomized 1:1 to receive:
KEYTRUDA (200 mg intravenously [IV] every three weeks [Q3W] for two cycles) as neoadjuvant therapy prior to surgery, followed by either KEYTRUDA (200 mg IV Q3W for 15 cycles) plus standard of care radiotherapy with cisplatin (100 mg/m2 IV Q3W for three cycles) as adjuvant therapy following surgery for high-risk patients or KEYTRUDA (200 mg IV Q3W for 15 cycles) plus standard of care radiotherapy without cisplatin as adjuvant therapy following surgery for low-risk patients; or
No neoadjuvant therapy prior to surgery, followed by adjuvant standard of care radiotherapy with cisplatin (100 mg/m2 IV Q3W for three cycles) as adjuvant therapy following surgery for high-risk patients or standard of care radiotherapy without cisplatin as adjuvant therapy following surgery for low-risk patients.
The safety profile of KEYTRUDA was consistent with that observed in previously reported studies. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 44.6% of patients receiving KEYTRUDA plus standard of care radiotherapy versus 42.9% of patients receiving standard of care radiotherapy alone. TRAEs led to death in 1.1% of patients receiving the KEYTRUDA regimen (n=4) and 0.3% of patients receiving standard of care radiotherapy (n=1). No new safety concerns were identified. Immune-mediated adverse events (AEs) of any grade occurred in 43.2% of patients receiving the KEYTRUDA regimen, most commonly hypothyroidism (24.7%).
About head and neck cancer
Head and neck cancer describes a number of different tumors that develop in or around the throat, larynx, nose, sinuses and mouth. Most head and neck cancers are squamous cell carcinomas that begin in the flat, squamous cells that make up the thin surface layer of the structures in the head and neck. Locally advanced head and neck squamous cell carcinoma (LA-HNSCC) is cancer that has grown outside the original location, but has not yet spread to distant parts of the body. There are several factors that greatly increase the risk of developing head and neck cancer, including tobacco and alcohol use and human papillomavirus (HPV). It is estimated there were more than 947,200 new cases of head and neck cancer diagnosed and over 482,400 deaths from the disease in 2022 globally. In the U.S., it is estimated there will be approximately 72,680 new cases of head and neck cancer diagnosed and more than 16,680 deaths from the disease in 2025.