Select protease inhibitors (PI) have been found to be effective in decreasing human papillomavirus oncoprotein expression. This study evaluated whether the topical PI, Saquinavir (SQV), promotes viral clearance in an infectious mouse model with Mus musculus papillomavirus I (MmuPV1). NOD scid gamma (NSG) mice were anally infected with similar to 4 x 10(8) viral genome equivalents of MmuPV1 and 120 days post-infection (when majority have high-grade anal dysplasia), began topical treatments: control (mock), 7,12-dimethylbenz(a)anthracene (DMBA) only, once weekly to promote carcinogenesis, 1% SQV only, daily (Monday - Friday), and SQV + DMBA. Viral MmuPV1 load was analyzed from anal lavages pre and post-treatment. Anal tissue was harvested, processed, and evaluated for drug absorption, grade of anal disease, and anal viral RNA. Results suggest that topical SQV promotes decreased viral shedding in female mice treated with SQV.

Anal cancer is a major health problem. This study seeks to determine if the topical protease inhibitor Saquinavir (SQV), is effective at the prevention of anal cancer in transgenic mice with established anal dysplasia. K14E6/E7 mice were entered into the study when the majority spontaneously developed high-grade anal dysplasia. To ensure carcinoma development, a subset of the mice was treated with a topical carcinogen: 7,12-Dimethylbenz[a]anthracene (DMBA). Treatment groups included: no treatment, DMBA only, and topical SQV with/without DMBA. After 20 weeks of treatment, anal tissue was harvested and evaluated histologically. SQV was quantified in the blood and anal tissue, and tissue samples underwent analysis for E6, E7, p53, and pRb. There was minimal systemic absorption of SQV in the sera despite high tissue concentrations. There were no differences in tumor-free survival between SQV-treated and respective control groups but there was a lower grade of histological disease in the mice treated with SQV compared to those untreated. Changes in E6 and E7 levels with SQV treatment suggest that SQV may function independently of E6 and E7. Topical SQV decreased histological disease progression in HPV transgenic mice with or without DMBA treatment without local side effects or significant systemic absorption.

Low-grade anal dysplasia is a disease that can progress to high-grade anal dysplasia and eventually anal cancer if left untreated. Research has shown that low-grade anal dysplasia is marked by significant autophagic dysfunction. We hypothesized that systemic induction of autophagy, via phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibition, would be effective in preventing anal cancer development in human papillomavirus (HPV) mice (K14E6/E7) with established low-grade anal dysplasia. Mice began treatment at 15 weeks of age, when 75% of mice spontaneously develop low-grade anal dysplasia, and were divided into the following groups: no treatment, systemic LY3023414 (4.5 mg/kg, dual PI3K/mTOR inhibitor) alone, topical 7,12 dimethylbenz[a]anthracene (DMBA) alone, or systemic LY3023414 and topical DMBA. Groups were compared for final histology, PI3K activity, mTOR activity, autophagic induction (light chain 3B (LC3β)), autophagic function (p62 protein), and tumor-free survival. Untreated mice or mice treated with LY3023414 alone did not progress to cancer. There was a statistically significant decrease in the number of mice that developed histologic evidence of cancer when comparing mice that received systemic LY3203414 with topical DMBA versus those that received topical DMBA alone (p = 0.0003). PI3K and mTOR activity decreased in groups treated with systemic LY3023414 and topical DMBA as compared with those treated with topical DMBA alone (p = 0.0005 and p = 0.0271, respectively). LC3β and p62 expression was not statistically altered with systemic LY3023414 treatment. Mice developed less overt tumors and had increased tumor-free survival when treated with systemic LY3023414 in the presence of topical DMBA compared to topical DMBA alone (p = 0.0016 and p < 0.001, respectively). Systemic LY3023414 treatment is effective in anal cancer prevention in the setting of established low-grade anal dysplasia in an HPV-associated mouse model of anal cancer.

Patients with immunodeficiencies and older age are at an increased risk of anal cancer. Transgenic K14E6/E7 mice with established high-grade anal dysplasia were treated topically at the anus with the protease inhibitor saquinavir (SQV) in the setting of CD4+ T-cell depletion to mimic immunodeficiency. To ensure tumor development, specific groups were treated with a topical carcinogen (7,12-Dimethylbenz[a]anthracene (DMBA)). The treatment groups included the vehicle (control), DMBA only, topical SQV, and topical SQV with DMBA, as well as the same four groups with CD4 depletion. The mice were monitored weekly for tumor development. Upon reaching 20 weeks of treatment, the mice were sacrificed, and their anal tissue was harvested for histological analysis. None of the mice in the SQV or control groups developed overt anal tumors, except three mice that were CD4-depleted. The CD4-depleted mice treated with DMBA had significantly increased tumor-free survival and overall survival as well as decreased tumor-volume growth over time when treated with SQV. These data suggest that topical SQV, in the setting of CD4 depletion and high-grade anal dysplasia, can increase tumor-free and overall survival; thus, it may represent a viable topical therapy to decrease the risk of progression of anal dysplasia to anal cancer.