New Therapeutic Cancer Vaccine with Lenalidomide Induces Potent T Cell Immunity and Inhibits HPV E6/E7-Expressing Tumor Growth in Mice.

Abstract

Current prophylactic human papillomavirus (HPV) vaccines prevent infection but have limited therapeutic benefit in established HPV-driven malignancies. To address this unmet need, we developed VTX-067, a modular self-assembling therapeutic cancer vaccine consisting of a recombinant Mycobacterium tuberculosis heat shock protein 70-avidin fusion (MAV) noncovalently bound to biotinylated HPV E6/E7 MHC class I- and II-restricted peptide concatemers. MAV is produced in CHO cells with minimal endotoxin. Assembled VTX-067 is designed to elicit both CD4⁺ and CD8⁺ T-cell responses against HPV-associated tumors. In multiple tumor models expressing HPV E6/E7, intradermal vaccination with VTX-067 induced potent and dose-dependent HPV E6/E7-specific CD8⁺ and CD4⁺ T-cell responses without evidence of local reactogenicity. Therapeutic vaccination significantly delayed subcutaneous tumor progression, extended survival, and provided durable protection against tumor rechallenge. VTX-067 treatment increased intratumoral CD8⁺ T-cell infiltration, elevated the CD8:Treg ratio, and upregulated a Th1/cytotoxic transcriptional program including Ifnγ, Tbx21, Stat1, and Gzmb. Depletion of CD8⁺ T cells eliminated vaccine efficacy, while adoptive transfer of VTX-067-primed CD8⁺ T cells conferred tumor protection in recipient mice. In a cervicovaginal orthotopic model, both intradermal and intramucosal administration generated systemic E6/E7-specific effector responses and sustained control of mucosal tumors. Notably, combining a suboptimal VTX-067 dose with the immunomodulatory agent lenalidomide further enhanced tumor control and survival, demonstrating a potential dose-sparing strategy. These findings establish VTX-067 as a safe, highly immunogenic therapeutic vaccine with CD8⁺ T-cell-dependent antitumor activity, and support its clinical development alone or in combination with immune-modulating agents for HPV-associated cancers.