FDA’s Approval of Keytruda for PD-L1 Positive Head and Neck Cancer Patients Signals a Clear Pathway for CEL-SCI’s Multikine to Address a Major Unmet Need in PD-L1 Negative Cancer Patients

On June 18, 2025 CEL-SCI Corporation (NYSE American: CVM) reported the U.S. Food and Drug Administration’s (FDA) approval of Merck’s KEYTRUDA (pembrolizumab), an anti-PD-1 therapy, for the treatment of adult patients with resectable locally advanced head and neck squamous cell carcinoma (HNSCC) whose tumors express PD-L1 (Combined Positive Score [CPS] ≥1) as determined by an FDA-approved test (Press release, Cel-Sci, JUN 18, 2025, View Source [SID1234653997]). Merck’s application was granted the FDA’s priority review on February 25, 2025, and regulatory approval was granted on June 13, 2025, based on interim results from Keytruda’s Phase 3 KEYNOTE-689 trial.

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Last week the FDA approved Keytruda as a perioperative (before and after surgery) treatment for resectable locally advanced head and neck cancer patients whose tumors express PD-L1 at a positive level. In Merck’s Phase 3 KEYNOTE-689 trial, Keytruda reduced the risk of recurrence and progression by 30%, compared with standard of care, in patients whose tumors expressed PD-L1 (CPS ≥1). The study did not show an improvement in overall survival. Patients with low to zero levels of PD-L1 did not benefit from Keytruda.

In contrast to the results of the KEYNOTE-689, CEL-SCI’s Phase 3 study showed that Multikine* treated patients whose tumors expressed low (Tumor Proportion Score [TPS <10]) to zero PD-L1, had their risk of death reduced by 66% (hazard ratio 0.34, 95% CI [0.18, 0.65], p=0.0012) and extended the 5-year overall survival to 73% compared to 45% in the standard of care, log rank p=0.0015. About 70% of the patients in CEL-SCI’s Phase 3 study had low to zero levels of PD-L1.

"It is encouraging for CEL-SCI that Merck’s Keytruda application received the FDA’s priority review and that marketing approval was given based on a Phase 3 study’s first pre-specified interim analysis. CEL-SCI has received the FDA’s go-ahead for a confirmatory Registration Study with 212 patients based on results from the completed Multikine Phase 3 study in head and neck cancer patients. The patients in the Phase 3 study that benefited from Multikine pre-surgery treatment showed an almost 4-year median overall survival advantage over control, and pre-surgery tumor responses to Multikine predicted survival benefit. The Keytruda approval based on pre-specified interim results strongly implies that Multikine has the potential for accelerated regulatory approval based on favorable post-surgical tumor responses," stated CEL-SCI’s CEO, Geert Kersten.