A phase 1/2a, dose-escalation, safety, and preliminary efficacy study of the RKP00156 vaginal tablet in healthy women and patients with cervical intraepithelial neoplasia 2.

Objective: This study aimed to determine the safety and efficacy of the RKP00156 vaginal tablet, a CDK9 inhibitor, in healthy women and patients with cervical intraepithelial neoplasia grade 2 (CIN2).

Methods: We conducted a phase 1/2a clinical trial of RKP00156. In step 1, RKP00156 at a dose of 10, 25, or 50 mg or a placebo tablet was administered transvaginally to 24 healthy women. In step 2, RKP00156 at a dose of 10, 25, or 50 mg or a placebo tablet was administered once daily for 4 weeks in 62 patients with CIN2. The primary endpoints of this trial were the safety of RKP00156 and the change in the human papillomavirus (HPV) viral load.

Results: A total of 86 patients were enrolled and randomized. RKP00156 administration did not cause serious drug-associated adverse events (AEs). Although no significant difference in the HPV viral load was found between the experimental and placebo groups, a reduction in the HPV viral load was observed in the 25 mg-dose group (-98.61%; 95% confidence interval=-99.83%, 4.52%; p=0.046) after treatment completion in patients with a high HPV viral load, despite a lack of statistical power. No differences in histologic regression and HPV clearance were observed.

Conclusion: The safety of RKP00156 was proved with no serious AEs. Although the study did not show any significance in histologic regression and HPV clearance, our findings indicate that RKP00156 may have a possibility of short-term inhibitory effect on HPV replication in patients with higher viral loads.

Trial Registration: ClinicalTrials.gov Identifier: NCT02139267.