Immune responses in a phase 2 clinical trial of peptide-based therapeutic human papillomavirus vaccine, PepCan, versus Candida adjuvant alone in treating cervical intraepithelial neoplasia 2/3.

person Mayumi Nakagawa University of Arkansas for Medical Sciences, Little Rock, AR info_outline Mayumi Nakagawa, Teresa Evans, Milan Bimali, Hannah Coleman, Jasmine Crane, Nadia Darwish, Yong-Chen Lu, Intawat Nookaew, Keanna Marsh, Michael Scott Robeson, Takeo Shibata, David Ussery, William Greenfield

Authors person Mayumi Nakagawa University of Arkansas for Medical Sciences, Little Rock, AR info_outline Mayumi Nakagawa, Teresa Evans, Milan Bimali, Hannah Coleman, Jasmine Crane, Nadia Darwish, Yong-Chen Lu, Intawat Nookaew, Keanna Marsh, Michael Scott Robeson, Takeo Shibata, David Ussery, William Greenfield Organizations University of Arkansas for Medical Sciences, Little Rock, AR Abstract Disclosures Research Funding National Instites of Health Background: A non-surgical alternative for treating cervical intraepithelial neoplasia (CIN2/3) would be desirable due to a risk of cervical incompetency in subsequent pregnancies. PepCan consists of four HPV 16 E6 peptides and a Candida skin testing reagent (Candin, Nielsen Biosciences),because of Candida ’s ability to regress common warts in humans, and to promote T cell proliferation and interleukin-12 secretion in vitro . We previously demonstrated safety and efficacy of Candida alone in comparison to a historical placebo for regressing CIN2/3 to no CIN ( p =0.0004 for intention-to-treat and p =0.0002 for per-protocol analyses). Methods: In this single center, randomized, double-blind Phase II study (NCT02481414), four intradermal injections of PepCan or Candida were given 3 weeks apart which were followed with two visits 6 months apart. Immune responses were assessed using interferon-g enzyme-linked immunospot (ELISPOT) assay for human papillomavirus (HPV), fluorescent-activated cell sorter (FACS) analysis for peripheral immune cells, and plasma measurements of 51 cytokines and metabolomics in patients who completed the 6-month visit (n=76). Cervical microbiome was also examined. For subjects who were HPV 16, 18, 35, or 52-positive at entry, epitope spreading was examined (n=32). In patients with sustained ELISPOT responses, bulk T cell receptor (TCR) b deep sequencing was performed (n=15). If the sustained ELISPOT responses were significant, single-cell RNA-seq and TCR sequencing were performed (n=5) for vaccine-induced HPV-specific T cells. Results: Following vaccination, new CD3 T cell responses to at least one region of the HPV 16 E6 protein were detected in 18 of 33 patients (54.5%) in the PepCan group and in 17 of 38 (44.7%) patients in the Candida group. Therefore, exogenous HPV antigens were not necessary to induce anti-HPV T cell responses. The histological responders demonstrated new E6 response in 14 of 31 (45.2%) and non-responders had it in 21 of 40 (52.5%). Pre-existing E6 responses were present in 12 of 31 (38.7%) of responders and 8 of 40 (20%) of non-responders. Epitope spreading was demonstrated in 7 of 18 patients (38.9%) in the PepCan group, in 8 of 14 (57.1%) patients in the Candida group, 6 of 10 (60%) histological responders and 9 of 22 (40.9%) histological non-responders. Plasma RANTES/CCL5 level was significantly and consistently decreased after vaccination ( p =0.004). Single-cell RNA-seq revealed increased expression of granzymes, CCR5, and EOMES in a histological responder, compared to non-responders. Conclusions: Administration of immune-enhancing adjuvant alone is sufficient for inducing anti-HPV immune responses. Consistent systemic decrease in RANTES/CCL5 was demonstrated suggesting possible mechanism in which Candida works through reducing RANTES/CCL5. Clinical trial information: NCT02481414.

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