Cancer Therapy: Preclinical Toll-like Receptor Agonist Imiquimod Facilitates Antigen-Specific CD8þ T-cell Accumulation in the Genital Tract Leading to Tumor Control through IFNg

Purpose: Imiquimod is a Toll-like receptor 7 agonist used topically to treat external genital warts and basal cell carcinoma. We examined the combination of topical imiquimod with intramuscular administration of CRT/E7, a therapeutic human papillomavirus (HPV) vaccine comprised of a naked DNA vector expressing calreticulin fused to HPV16 E7. Experimental Design: Using an orthotopic HPV16 E6/E7þ syngeneic tumor, TC-1, as a model of highgrade cervical/vaginal/vulvar intraepithelial neoplasia, we assessed if combining CRT/E7 vaccination with cervicovaginal deposition of imiquimod could result in synergistic activities promoting immune-mediated tumor clearance. Results: Imiquimod induced cervicovaginal accumulation of activated E7-specific CD8þ T cells elicited by CRT/E7 vaccination. Recruitment was not dependent upon the specificity of the activated CD8þ T cells, butwas significantly reduced inmice lacking the IFNg receptor. Intravaginal imiquimoddeposition induced upregulation of CXCL9 and CXCL10mRNA expression in the genital tract, which are produced in response to IFNg receptor signaling and attract cells expressing their ligand, CXCR3. The T cells attracted by imiquimod to the cervicovaginal tract expressed CXCR3 as well as CD49a, an integrin involved in homing and retentionofCD8þT cells atmucosal sites.Our results indicate that intramuscular CRT/E7 vaccination in conjunction with intravaginal imiquimod deposition recruits antigen-specific CXCR3þ CD8þ T cells to the