Intradermal vaccination of HPV-16 E6 synthetic peptides conjugated to an optimized Toll-like receptor 2 ligand shows safety and potent T cell immunogenicity in patients with HPV-16 positive (pre-)malignant lesions

Speetjens, F.M.; Welters, M.J.P.; Slingerland, M.; Poelgeest, M.I.E. van; Steenwijk, P.J.D. van; Roozen, I.; ... ; Ossendorp, F. (2022)

Article / Letter to editor

Background: Amplivant is a molecularly optimized Toll-like receptor 2 ligand that can be covalently conjugated to tumor peptide antigens. In preclinical models, amplivant-adjuvanted synthetic long peptides (SLPs) strongly enhanced antigen presentation by dendritic cells, T cell priming and induction of effective antitumor responses. The current study is a first-in-human trial to investigate safety and immunogenicity of amplivant conjugated to human papillomavirus (HPV) 16-SLP. Methods: A dose escalation phase I vaccination trial was performed in 25 patients treated for HPV16 positive (pre-) malignant lesions. Amplivant was conjugated to two SLPs derived from the two most immunodominant regions of the HPV16 E6 oncoprotein. The vaccine, containing a mix of these two conjugates in watery solution without any other formulation, was injected intradermally three times with a 3-week interval in four dose groups (1, 5, 20 or 50 mu g per conjugated peptide). Safety data were collected during the study. Peptide-specific T cell immune responses were determined in blood samples taken before, during and after vaccination using complementary immunological assays. Results: Toxicity after three amplivant-conjugated HPV16-SLP vaccinations was limited to grade 1 or 2, observed as predominantly mild skin inflammation at the vaccination site and sometimes mild flu-like symptoms. Adverse events varied from none in the lowest dose group to mild/moderate vaccine-related inflammation in all patients and flu-like symptoms in three out of seven patients in the highest dose group, after at least one injection. In the lowest dose group, vaccine-induced T cell responses were observed in the blood of three out of six vaccinated persons. In the highest dose group, all patients displayed a strong HPV16-specific T cell response after vaccination. These HPV16-specific T cell responses lasted until the end of the trial. Conclusions: Amplivant-conjugated SLPs can safely be used as an intradermal therapeutic vaccine to induce robust HPV16-specific T cell immunity in patients previously treated for HPV16 positive (pre-) malignancies. Increased vaccine dose was associated with a higher number of mild adverse events and with stronger systemic T cell immunity.

• All authors: Speetjens, F.M.; Welters, M.J.P.; Slingerland, M.; Poelgeest, M.I.E. van; Steenwijk, P.J.D. van; Roozen, I.; Boekestijn, S.; Loof, N.M.; Zom, G.G.; Valentijn, A.R.P.M.; Krebber, W.J.; Meeuwenoord, N.J.; Janssen, C.A.H.; Melief, C.J.M.; Marel, G.A. van der; Filippov, D.V.; Burg, S.H. van der; Gelderblom, H.; Ossendorp, F.
• Date: 2022-10-01
• Journal: Journal for ImmunoTherapy of Cancer
• Volume: 10
• Issue: 10
• DOI: doi:10.1136/jitc-2022-005016