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

FDA priority review and approval based on interim results sets a positive precedent, paving the path for future Multikine approval

Multikine reduced the risk of death by 66% compared to standard of care in the target population of patients with low and zero PD-L1, while Keytruda reduced the risk of recurrence and progression (EFS) by 30% compared with standard of care in patients whose tumors expressed higher PD-L1 without demonstrating improvement in overall survival

Pre-operative treatments from CEL-SCI and Merck have the potential to offer clinical benefit for locally advanced resectable head and neck cancer patients across the PD-L1 expression spectrum

CEL-SCI Corporation (NYSE:CVM) today applauded 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. 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.

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.

About CEL-SCI Corporation

CEL-SCI believes that boosting a patient's immune system before surgery, radiotherapy and chemotherapy have damaged it should provide the greatest possible impact on survival. Multikine is designed to help the immune system "target" the tumor at a time when the immune system is still relatively intact and thereby thought to be better able to mount an attack on the tumor.

Multikine (Leukocyte Interleukin, Injection), given right after diagnosis and before surgery, has been dosed in over 740 patients and received Orphan Drug designation from the FDA for neoadjuvant therapy in patients with squamous cell carcinoma (cancer) of the head and neck. Based on the data from the completed randomized controlled Phase 3 study, the FDA concurred with CEL-SCI's target patient selection criteria and gave the go-ahead to conduct a confirmatory Registration Study. The study will enroll 212 newly diagnosed locally advanced primary treatment naïve resectable head and neck cancer patients.

The Company has operations in Vienna, Virginia, and near/in Baltimore, Maryland.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. When used in this press release, the words "intends," "believes," "anticipated," "plans" and "expects," and similar expressions, are intended to identify forward-looking statements. Such statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected. Factors that could cause or contribute to such differences include an inability to duplicate the clinical results demonstrated in clinical studies, timely development of any potential products that can be shown to be safe and effective, receiving necessary regulatory approvals, difficulties in manufacturing any of the Company's potential products, inability to raise the necessary capital, inability to finalize a partnering agreement and the risk factors set forth from time to time in CEL-SCI's filings with the Securities and Exchange Commission, including but not limited to its report on Form 10-K for the year ended September 30, 2024. The Company undertakes no obligation to publicly release the result of any revision to these forward-looking statements which may be made to reflect the events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.

* Multikine (Leukocyte Interleukin, Injection) is the trademark that CEL-SCI has registered for this investigational therapy. This proprietary name is subject to FDA review in connection with the Company's future anticipated regulatory submission for approval. Multikine has not been licensed or approved for sale, barter or exchange by the FDA or any other regulatory agency. Similarly, its safety or efficacy has not been established for any use.

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COMPANY CONTACT:

Gavin de Windt

CEL-SCI Corporation

(703) 506-9460