Randomized Phase IIa Trial of Purified Candida Antigen for Common Warts: Evaluating the Safety and Efficacy Across Multiple Dosing Regimens.

Background: Non-standardized Candida albicans antigens are commonly used for the treatment of common warts (verruca vulgaris); however, clinical studies thus far have not determined optimal dosing. This study assessed three dosing schemes using Candin®, a standardized purified Candida antigen (PCA), for the treatment of common warts.

Methods: This placebo-controlled, randomized phase IIa clinical trial included participants that had 3 to 20 injectable common warts on prespecified anatomical regions. PCA was administered intralesionally for up to 10 injections every 2 weeks, with adjustments to every 3 weeks for local tolerance issues. Three dosing regimens were evaluated: 0.3 or 0.5 mL into a single wart (cohorts 1 and 2, respectively), or 0.3 mL into up to four warts (cohort 3). Total injection volumes in cohorts 2 and 3 were larger than the typical off-label use of C. albicans. The primary outcome was complete resolution of injected warts, while secondary outcomes included safety, tolerability, and the clearance of untreated common warts.

Results: The incidence of clearance of the primary injected wart in placebo participants was 41.9%, compared to 65.9% (relative risk [RR] 1.57; 95% confidence interval [CI] 1.02, 2.42; P = 0.03) in cohort 1, 79.5% (RR 1.89; 95% CI 1.27, 2.82; P = 0.0007) in cohort 2, and 72.5% (RR 1.74; 95% CI 1.19, 2.50; P = 0.005) in cohort 3, and treatment was well tolerated. Injection of 0.5 mL PCA into a single wart also resulted in a significantly higher rate of clearance of untreated common warts compared to placebo (RR 3.2, 95% CI 1.2, 8.0, P = 0.001).

Conclusions: All three dosing regimens of PCA were safe, well tolerated, and resulted in significantly greater clearance of the primary treated wart(s) compared to placebo, but only 0.5 mL injected into a single wart was significantly better than placebo at clearing untreated warts. Typically, a volume of 0.3 mL C. albicans antigen is injected into a single wart; however, these results suggest that a larger volume of 0.5 mL may have greater benefit for patients. A phase III clinical trial is currently underway to confirm these findings. Background: ClinicalTrials.gov NCT02393417.