A randomized pilot study of HPV16 L2E7E6 fusion protein vaccination site post-treatment for HPV16+ cervical cancer

Since anti-tumor immunity is enhanced by vaccination of mice adjacent to human papillomavirus type 16 (HPV16+) tumors, we examined whether HPV16 L2E7E6 fusion protein (TA-CIN) vaccination in the thigh of HPV16+ cervical cancer patients would be more immunogenic than their arm.

HPV16+ cervical cancer (stage IB1-IVA) patients, who had completed standard-of-care treatment within the past year and absent evidence of disease (NED), were enrolled in a pilot study (NCT02405221). Participants were randomized 1:1 to receive three 100 μg TA-CIN monthly intramuscular immunizations either in the arm or thigh and followed for two years for safety (CTCAEv4.0), immune response, and recurrence.

Fifteen patients were enrolled (median age 44, range 35-83 years); one patient experienced a non-vaccine-related adverse event after one vaccination and withdrew. Treatment-related adverse events (n = 8) were grade 1, primarily at the injection site, and self-resolved. No recurrence was observed. TA-CIN-specific antibody titers tended to be higher in thigh-vaccinated patients. Bulk TCRseq revealed significant increases in expanded and de novo T cell clones following thigh-vaccination compared with the arm. No correlation with prior treatment modality was observed. E6-, E7-, and L2-specific TCR clones expanded, although L2-specific T cell responses were predominant. One month post-vaccination, scRNAseq revealed significant expansion of MAIT and cytotoxic CD8+ T cells, and both expanded and novel TCR clonotypes were identified in the latter.

Thigh or arm vaccination with TA-CIN was well tolerated, but the former elicited higher CD8 T cell and antibody responses in HPV16+ cervical cancer patients with NED after primary therapy.