Long-Term Follow-up Study of Cantharidin (YCANTH [VP-102/TO-208]) in Patients With Common Warts (Verruca Vulgaris)

Inclusion Criteria: Candidates will be included in the study if they: 1. Meet ≥ 1 of the following criteria: 1. Completed the Day 84 visit in the parent study and have ≥ 1 treatable common warts. 2. Completed the Day 105 visit in the parent study and have ≥ 1 treatable common warts. 3. Completed the Day 147 visit in the parent study. 2. Provide written informed consent or assent in a manner approved by the Institutional Review Board (IRB) and/or have a parent/guardian provide written informed consent as evidenced by the signature on an IRB approved assent/consent form. Subjects who turn 18 years of age (or legal age per state or country) during the study may be required to re consent to remain on the study (follow the state or country regulatory requirements). 3. Agree to refrain from swimming, bathing, or prolonged immersion in water or any liquids until the study drug is removed after each treatment. 4. Have the ability, or have a parent/guardian with the ability, to follow study instructions and the willingness to complete all study requirements. 5. Agree not to use any wart-removing product (prescription or over-the-counter) other than the study drug during the course of the study with the exception of circumstances for excluded wart types. Excluded warts include common warts located in excluded areas that will not be treated or evaluated during the study as well as genital, plantar, or anal warts: a. If treatment of these excluded wart types is required during the study, it should be limited to destructive therapy such as cryosurgery and warts cannot be within 10mm of any warts that are under study. 6. Provide written authorization for use and disclosure of protected health information (per state and/or country requirements). 7. If participating in the optional photographic assessment, agree to allow photographs of treatable common warts to be taken at selected visits by the research team. Exclusion Criteria: Candidates will be excluded from the study if they: 1. Are unable to cooperate with the requirements or visits of the study, as determined by the Investigator. 2. Have any warts present at study entry in an allowed anatomic location that the subject, parent/guardian, or Investigator is unwilling to treat. 3. Are systemically immunosuppressed or have taken required systemic immunosuppressive or immunomodulatory medication (including oral or parenteral corticosteroids) within 30 days before enrollment or such treatment is planned to be required during the course of the study. Routine use of local (eg, topical, inhaled, intranasal) corticosteroids and episodic use of systemic medications to treat conditions arising during the study is allowed. 4. Have any chronic or acute medical condition that, in the opinion of the Investigator, may interfere with the study results or place the subject at undue risk (eg, human immunodeficiency virus, systemic lupus erythematosus, viral hepatitis, uncontrolled diabetes). 5. Have had any previous treatment (including an investigational agent in a clinical trial) of common warts, including but not limited to the use of cantharidin, imiquimod, antivirals, retinoids, topical salicylic acid, lactic acid, hydrogen peroxide, trichloroacetic acid, pulse dye laser, iodine-based or nitric oxide-based therapies, oral cimetidine, coix seed, intralesional immunotherapy, curettage, or freezing of warts in the 30 days before treatment. 6. Immunizations (eg, flu shots) may be administered throughout the study, but not within 5 days before or after any treatment with study drug. 7. Have received any investigational product as part of a clinical trial NOT related to the treatment of common warts within 30 days before the first application of the study drug. 8. Have epidermodysplasia verruciformis. 9. Have an active malignancy or are undergoing treatment for any malignancy. 10. Have a clinically significant medical, psychiatric, emotional condition, or abnormality that, in the opinion of the Investigator, would compromise the safety of the subject or the quality of the data. 11. Have a hypersensitivity or an idiosyncratic reaction to YCANTH (VP-102/TO-208) or related compounds, or drug product excipients (acetone, ethyl alcohol, nitrocellulose, hydroxypropyl cellulose, castor oil, camphor, gentian violet, and denatonium benzoate). 12. Have a condition or situation that may interfere significantly with the subject's participation in the study (eg, subjects who require hospitalization for an acute or chronic condition including alcohol or drug abuse), at the determination of the Investigator. 13. Are sexually active or may become sexually active and are unwilling to practice responsible birth control methods (eg., combination of condoms and foam, birth control pills, intrauterine device, patch, shot and vaginal ring). Withdrawal is not an acceptable method of birth control. Females who have reached menarche must have a negative urine pregnancy test at each visit before treatment with YCANTH (VP-102/TO-208). 14. Are pregnant or breastfeeding.