CEL-SCI Corporation announced new data from a biomarker analysis of its pivotal Phase 3 study in newly diagnosed locally advanced squamous cell carcinoma of the head and neck (SCCHN) at the American Head and Neck Cancer Society’s (AHNS) 11th Annual International Conference on Head and Neck Cancer on July 10, 2023 in Montreal, Canada, in the presentation titled “Tumor cell PD-L1 biomarker confirms Leukocyte Interleukin Injection (LI) treatment (Tx) survival outcome advantage in naïve locally advanced primary head & neck squamous cell carcinoma (SCCHN), the IT-MATTERS Study”. The Leukocyte Interleukin Injection (LI) [aka Multikine*] talk, was delivered by Philip Lavin, PhD, lead biostatistician for over 80 regulatory approvals/clearances who has also served on multiple U.S. Food and Drug Administration (FDA) review panels. Dr. Lavin is the lead biostatistician for CEL-SCI’s IT-MATTERS study.

Tumor cell PD-L1, also known as PD-L1 (Programmed Death-Ligand 1), a protein that plays a crucial role in immune system regulation, is a target pathway for immune checkpoint inhibitors, a major class of oncology drugs. These work by blocking the interaction between tumor cell PD-L1 and the PD-1 receptor. The global PD-L1/PD-1 therapeutics market was valued at $34.8 billion in 2022 and includes two drugs approved for head and neck cancer, specifically unresectable recurrent or metastatic SCCHN, Keytruda and Opdivo.

While pembrolizumab (Keytruda) and nivolumab (Opdivo) are approved for use in recurrent and metastatic head and neck cancer, CEL-SCI’s Phase 3 data showed that Multikine prolonged overall survival in the lower risk for recurrence advanced primary head and neck cancer patients and more so in a subset comprising >70% of the lower-risk patients (all had low levels (defined as TPS<10) of tumor cell PD-L1 expression). The AHNS presentation focused on biomarker analysis, specifically featuring tumor cell PD-L1, from tumor specimens that were collected from nearly half of the patients in CEL-SCI’s pivotal Phase 3 study. In June of 2021, a Multikine study reported a statistically significant 14.1% absolute 5-year overall survival benefit in the intent to treat (ITT; n=923) subjects who were categorized as lower risk for recurrence (LR; n=380) per National Comprehensive Cancer Network (NCCN) guidelines and received Multikine followed by surgery and radiotherapy, as compared to control LR subjects who received only standard of care (SOC) (surgery plus radiotherapy), resulting in a near 4-year median overall survival advantage over control (101.7 vs 55.2 months).

The Company is pursuing paths to marketing approval for Multikine in the treatment of head and neck cancer in the USA, Canada, the UK and the European Union. Highlights of the data they presented at AHNS conference include: A Kaplan-Meier lifetable for low tumor cell PD-L1 (defined as TPS <10) demonstrated a significant log rank test (2-sided p=0.034) favoring the Multikine plus Standard of care (SOC) group vs SOC alone; there was an absolute 20% survival advantage at 5-year favoring both Multikine plus SOC (~60% alive) vs SOC alone (~40% alive). The PD-L1 low subgroup represents >70% of all LR subjects.

Two-way and three-way interaction models for the LR population confirmed statistical significance favoring Multikine treatment regimen plus SOC vs SOC alone with a 0.6 hazard ratio for 3-way interaction and a 0.55 hazard ratio for the 2-way interaction vs 0.68 hazard ratio for the study LR population that contained all patients, not just those with low PD-L1 (TPS <10). The data suggest potential benefits for combining Multikine with checkpoint inhibitors to further improve overall survival outcome in this hard-to-treat patient population.