Phase 1 Clinical Trial of Intralesional Injection of Candida Antigen for the Treatment of Warts

Warts are benign epidermal tumors caused by human papillomaviruses (HPVs). There are more than 100 distinct HPV types that have been isolated from cutaneous and mucosal lesions, of which the closely related HPV types 2, 27, and 57 predominantly cause common warts.¹

It is well established that cell-mediated immune response plays a major role in controlling HPV infections.² Therefore, treatment techniques such as immunotherapy have been used to activate the immunologic response to HPV. One method of immunotherapy is the intralesional injection of skin test antigens such as Candida, mumps, and/or Trichophyton. Studies have shown that such therapies resolve not only the treated warts but also distant, untreated warts.³

To our knowledge, little work has been done to elucidate the immunologic mechanisms behind skin test antigens immunotherapy. Herein, we report immunologic response data from patients undergoing Candida injection immunotherapy for the treatment of warts, measured by an ex vivo interferon γ–enzyme-linked immunospot (IFN-γ ELISPOT) assay.

The study protocol was approved by the institutional review board of the University of Arkansas for Medical Sciences (UAMS), and the clinicaltrials.gov identifier is NCT00569231. Patients were recruited during the period between February 2007 and May 2009 from the outpatient Dermatology Clinic at UAMS. Informed consent was obtained from all participants.

Eighteen patients, each with at least 2 cutaneous, nongenital, nonfacial warts and no previous Candida antigens treatment for warts were enrolled into the study. Each patient received an intralesional injection of 0.3 mL of Candida antigen (Candin; Allermed Laboratories, San Diego, California) into their largest wart at the baseline visit and then at each visit every 3 weeks thereafter. The clinical responses and adverse events were assessed.

The sequences of antigens used in the ex vivo IFN-γ ELISPOT assay were chosen from HPV-57 since HPV-2a, -27, and -57 were the most common HPV types detected in the warts of patients previously recruited in our clinics.³ The peptide sequences that contained HLA class I A2 hot spots and HLA class II DR hot spots and that were similar among HPV-2a, -27, and -57 were chosen using the predictive engines of MULTIPRED⁴: HPV-57 E1-peptide-(231-260 and 251-286), E2-peptide-(188-208), E4-peptide-(10-30), E6-peptide-(17-55), and L1-peptide-(380-412). The IFN-γ ELISPOT assay protocol was performed as previously described,⁵ except 300 000 peripheral blood mononuclear cells were presented with 10 μM of each of the HPV-57 peptides, and the incubation period was extended to 40 hours.

Eighteen patients were enrolled, and 11 completed the study (Table). Of the 11 patients who completed the study, 9 had complete resolution of their treated warts (82%), 1 had partial resolution (9%), and 1 had no response (9%). Complete resolution of the first distant untreated warts was observed in 6 of 8 patients (75%), while that of the second distant warts were observed in 6 of 6 patients (100%). The median number of injections required for complete resolution was 4. None of the 18 patients experienced vaccine-related adverse events higher than grade 2 (moderate). Typical adverse events were injection site pain and mild erythema.

The IFN-γ ELISPOT assay was performed on only 10 of the 11 patients who completed the study (Table) because the sample from the 11th patient was lost to improper thawing. A positive response to HPV-57 L1-peptide-(380-412) was the response most commonly detected (6 of 10, 60%). One patient demonstrated a response to HPV-57 E4-peptide-(10-30) (10%) (data not shown). No responses were detected to the other peptides or to the Candida antigen. All samples tested positive against phytohemagglutinin-positive control. In relation to the clinical response, 6 of 9 responders had a positive response to the L1-peptide (67%), suggesting that L1-specific T cells may play a role in wart regression. The 1 nonresponder had no positive results.

In this study, serial injections of Candida antigen were shown to be a safe treatment for warts and resulted in good clinical responses. Among the 6 HPV-57 peptides examined, the immune response to HPV-57 L1-peptide-(380-412) was most commonly detected, and all of the patients with this response demonstrated at least partial resolution of their wart(s). These results suggest that L1-specific T cells may be involved in wart regression. To our knowledge, this is the first demonstration of HPV-57 L1-specific immune response. One implication of this finding is that incorporating the HPV-57 L1-peptide-(380-412) with Candida antigens may represent a new treatment option for common warts. However, more definitive evidence that HPV-57 L1-specific T cells play a role in wart regression needs to be obtained by comparing the T-cell responses between a Candida antigen–treated group and a placebo group in a study with a larger number of patients. In short, serial injections of Candida antigen is a safe treatment for common warts that may work through enhancing anti-HPV T-cell responses.

Correspondence: Mr Kim, 4301 W Markham St, Slot 852, Little Rock, AR 72205 (khkim@uams.edu).

Accepted for Publication: July 21, 2010

Author Contributions: Mr Kim and Dr Nakagawa had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Kim, Horn, Pharis, and Nakagawa. Acquisition of data: Kim, Pharis, Kincannon, Jones, O’Bryan, Myers, and Nakagawa. Analysis and interpretation of data: Kim, Horn, and Nakagawa. Drafting of the manuscript: Kim, Horn, and Nakagawa. Critical revision of the manuscript for important intellectual content: Kim, Pharis, Kincannon, Jones, O’Bryan, Myers, and Nakagawa. Obtained funding: Nakagawa. Administrative, technical, and material support: Kim, Horn, Pharis, Jones, O’Bryan, and Myers. Study supervision: Horn, Kincannon, and Nakagawa.

Financial Disclosure: A patent application was filed based on the results of this study, and Mr Kim and Drs Horn and Nakagawa were named as the inventors. While Dr Horn has not received payment to perform the work for this study, he has a significant ownership interest in Type IV Technologies LLC, a company formed through the University of Arkansas for Medical Sciences Biotechnology Center. This company was created to market a product based on use of the antigen used in this article.

Funding/Support: This study was supported by the University of Arkansas for Medical Sciences College of Medicine Intramural Grant for an Individual Pilot Study (Dr Nakagawa).

Role of the Sponsors: The sponsor had no role in the design and conduct of the study; in the collection, analysis, and interpretation of data; or in the preparation, review, or approval of the manuscript.

Additional Contributions: The Candin used in this study was provided without charge by Allermed Laboratories Inc.