© 2019 The Authors Background: While prophylactic human papillomavirus (HPV) vaccination exists, women are still developing cervical intraepithelial neoplasia (CIN) grade 2 or 3 for which an immunotherapeutic, non-surgical, approach may be effective. The primary aim was to assess the efficacy of tipapkinogen sovacivec (TS) vaccine in achieving histologic resolution of CIN2/3 associated with high risk (HR) HPV types. Methods: Women 18 years and older who had confirmed CIN2/3 were enrolled in a randomized, double blind, placebo-controlled phase II trial and assigned to drug in a 2:1 ratio (vaccine:placebo). The primary endpoint occurred at month 6 when the excisional therapy was performed; cytology and HR HPV typing were performed at months 3, 6 and every six months through month 30. The safety population included all patients who received at least one dose of study drug. Results: Of the 129 women randomized to vaccine and 63 to placebo, complete resolution was significantly higher in the vaccine group than placebo for CIN 2/3 regardless of the 13 HR HPV types assayed (24% vs. 10%, p < 0.05); as well as for only CIN 3 also regardless of HR HPV type (21% vs. 0%, p < 0.01). Irrespective of baseline HPV infection, viral DNA clearance was higher in the vaccine group compared to placebo (p < 0.01). The vaccine was well tolerated with the most common adverse events being injection site reactions. Conclusions: The TS vaccine provides histologic clearance of CIN 2/3 irrespective of HR HPV type in one third of subjects and is generally safe through 30 months.