Background: The synthetic long peptide (SLP) vaccine against the human papillomavirus type 16 (HPV16) oncoproteins E6 and E7 applied to high-grade premalignant HPV16-induced lesions of the vulva was safe and resulted in successful clearance of the lesion in half of the patients correlating with strong and broad T-cell responses against the vaccine peptides. However, in HPV16⁺ cervical cancer patients the vaccine responses were less vigorous and not sufficient for tumor regression. A second generation SLP vaccine was formulated, in which two E6 long peptides were conjugated to a synthetic Toll-like receptor 2 (TLR2) ligand called Amplivant. The TLR2 ligand-SLP conjugates were shown to enhance antigen presentation by dendritic cells, thereby improving induction of effective anti-tumor T cells in vitro and in preclinical studies. The two selected E6 peptides are immunodominant peptides containing both CD4⁺ and CD8⁺ T-cell epitopes in natural HPV16 immunity and upon vaccination with HPV16-SLP in previous clinical trials. Methods: In a recently initiated phase I clinical trial the two with Amplivant conjugated E6 peptides as a mixture (the vaccine is called Hespecta; HPV E Six Peptide Conjugated To Amplivant) were administered to HPV16⁺ oropharyngeal cancer patients, who first were treated with curative intent. Four dose escalation levels will be tested in six patients per peptide dose, namely 1, 5, 20 or 50 μg of conjugated peptides. The vaccine is administered intradermally three times with a three-week interval. The decision to start enrolment at the next dose level is made by assessing the safety after 4 out of 6 patients have completed the first follow-up visit after the third vaccination with the previous dose level. The dose escalation phase will be discontinued if in two or more patients a grade 3 or 4 vaccine-related toxicity occurs. The primary objective is to determine the ability of the vaccine to induce HPV16 E6-specific T-cell responses. The secondary objective is to study the safety of Hespecta. Currently, 2 patients have been enrolled. Clinical trial information: 2014-000658-12.