The purpose of this study is to determine the safety and tolerability of pharmaceutical compound 31510 in a topical cream when applied to in situ cutaneous squamous cell carcinoma and to obtain preliminary efficacy data for the treatment of in situ cutaneous squamous cell carcinoma by Compound 31510 topical cream.

Inclusion Criteria:

• Male or female adults > 18 years of age
• Primary, histologically confirmed SCCIS with a minimum area of 0.5 cm2 and with a maximum diameter of 2.0 cm target SCCIS lesion suitable for excision
• Histological diagnosis made no more than 4 weeks prior to the screening visit
• Histological biopsy removed 25% or less of the target lesion
• No other dermatological disease in the SCCIS target site or surrounding area
• Willing to refrain from using non-approved lotions or creams on the target site and surrounding area during the treatment period. Willing to refrain from washing the treated area for at least 8 hours following the application of study medication
• Willing to refrain from exposure to direct sunlight or ultraviolet light and to avoid the use of tanning parlors for the duration of the study
• Laboratory values for the tests listed in the Study Schedule on page 2 within the reference ranges as defined by the central laboratory, or "out of range" test results that are clinically acceptable to the investigator.
• Ability to follow study instructions and likely to complete all study requirements
• Written informed consent obtained, including consent for tissue to be examined and stored by the central dermatopathologist.
• Written consent to allow photographs of the target SCCIS lesion to be used as part of the study data
• For females of childbearing potential, a negative pregnancy test at screening and using an acceptable form of birth control (oral/implant/injectable/transdermal contraceptives, intrauterine device, condom, diaphragm, abstinence, or a monogamous relationship with a partner who has had a vasectomy)

Exclusion Criteria:

• Pregnant or lactating
• Presence of known or suspected systemic cancer
• Histological evidence of nBCC, sBCC, or any other tumor in the biopsy specimen
• Histological evidence of severe squamous metaplasia, infiltrative, desmoplastic or micronodular growth patterns in the biopsy specimen
• History of recurrence of the target SCCIS lesion
• Evidence of dermatological disease or confounding skin condition in the treatment area, e.g., BCC, actinic keratosis, rosacea, psoriasis, atopic dermatitis, eczema, xeroderma pigmentosa
• Concurrent disease or treatment that suppresses the immune system
• Chronic medical condition that in the judgment of the investigator(s) would interfere with the performance of the study or would place the patient at undue risk
• Known sensitivity to any of the ingredients in the study medication
• Use of a tanning parlor or other excessive or prolonged exposure to ultraviolet light or direct sunlight during the course of the study
• Treatment with systemic chemotherapeutic agents within the 6 months prior to the screening visit
• Use of systemic retinoids within the 6 months prior to the screening period
• Treatment with systemic immunomodulators or immunosuppressants within the 6 months prior to the screening period
• Use of topical immunomodulators within 2 cm of the target SCCIS lesion within the 4 weeks prior to the screening period
• Treatment with the following topical agents within the 4 weeks prior to the screening visit; levulinic acid, 5-fluorouracil, corticosteroids, retinoids, diclofenac, hyaluronic acid, imiquimod
• Undergone a facial resurfacing procedure, i.e., chemical peel, laser resurfacing, dermabrasion, within the 6 months prior to the screening visit, if the target SCCIS lesion is on the face
• Treatment with liquid nitrogen, surgical excision or curettage within 2cm of the target SCCIS lesion during the 4 weeks prior to the screening visit
• Elective surgery within 4 weeks prior to the screening visit, during the study, or 4 weeks after the treatment period
• Evidence of current chronic alcohol or drug abuse
• Current enrollment in an investigational drug or device or participation in such a study within 4 weeks of the screening visit
• In the investigator's opinion, evidence of unwillingness, or inability to follow the restrictions of the protocol and complete the study

All subjects in this study were treated with a formulation of CoQ10 3% topical cream that was applied twice daily for 6 weeks. The mean duration (SD) of treatment was 41.4 days (6.7) and ranged from 21 to 47 days.