Open Label, Dose Escalation Study for the Safety and Efficacy of STP705 in Adult Patients With isSCC

Inclusion Criteria: * 1\. Male or female adult ≥ 18 years of age. * 2\. Primary, histologically confirmed trunk or extremity (non-peri-orbital/-anogenital/-facial/-scalp) isSCC lesion suitable for excision with a minimum diameter of 0.5cm and with a maximum diameter of 2.0cm. * 3\. Histological diagnosis made no more than 6 months prior to the screening visit. * 4\. Histological biopsy removed ≤25% of the original area of the target lesion. * 5\. No other dermatological disease in the isSCC target site or surrounding area, which in the opinion of the investigator, could interfere with the study. * 6\. Willing to refrain from using non-approved lotions or creams on the target site and surrounding area during the treatment period. * 7\. Willing to refrain from exposure to excessive direct sunlight or ultraviolet light and to avoid the use of tanning parlors for the duration of the study. * 8\. Laboratory values for the tests (listed in the Study Schedule) within the reference ranges as defined by the central laboratory, or "out of range" test results that is clinically acceptable to the investigator. Acceptable "out of range" values are generally those within 2 standard deviations of the mean or explainable due to concurrent medications or disease processes. * 9\. Ability to follow study instructions and likely to complete all study requirements. * 10\. Written informed consent obtained, including consent for tissue to be examined and stored by the Central Histology Lab. * 11\. Written consent to allow photographs of the target isSCC lesion to be used as part of the study data and documentation. * 12\. 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: * 1\. Pregnant or lactating. * 2\. Presence of known or suspected systemic cancer. * 3\. Histological evidence of nBCC, sBCC, invasive SCC, or any other non-isSCC tumor in the biopsy specimen. * 4\. Histological evidence of severe squamous metaplasia, infiltrative, desomoplastic or micronodular growth patterns in the biopsy specimen. * 5\. History of recurrence of the target isSCC lesion. * 6\. Prior exposure to STP705. * 7\. Evidence of dermatological disease or confounding skin condition in the treatment area, e.g., BCC, actinic keratosis, rosacea, psoriasis, atopic dermatitis, eczema, xeroderma pigmentosa. * 8\. Concurrent disease or treatment that suppresses the immune system; * 9\. Patients with baseline QTC \> 480 msec using Frederica's formula * 10\. 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. * 11\. Known sensitivity to any of the ingredients in the study medication. * 12\. Use of a tanning beds or other excessive or prolonged exposure to ultraviolet light or direct sunlight during the study. * 13\. Treatment with systemic chemotherapeutic agents within the 6 months prior to the screening visit. * 14\. Use of systemic retinoids within the 6 months prior to the screening period. * 15\. Treatment with systemic immunomodulators or immunosuppressants within the 6 months prior to the screening period. * 16\. Use of topical immunomodulators within 2cm of the target isSCC lesion within the 4 weeks prior to the screening period. * 17\. Treatment with the following topical agents within 2cm of the target isSCC lesion within the 4 weeks prior to the screening visit: amino-levulanic acid, 5-fluorouracil, corticosteroids, retinoids, diclofenac, ingenol mebutate, or imiquimod. * 18\. Treatment with liquid nitrogen, surgical excision (excluding diagnostic incisional biopsy) or curettage within 2cm of the target isSCC lesion during the 4 weeks prior to the screening visit. * 19\. Elective surgery within 4 weeks prior to the screening visit, during the study, or 4 weeks after the study period. * 20\. Evidence of current chronic alcohol or drug abuse. * 21\. Current enrollment in an investigational drug or device study or participation in such a study within 4 weeks of the screening visit. * 22\. In the investigator's opinion, evidence of unwillingness, or inability to follow the restrictions and requirements of the protocol and complete the study. * 23\. Taking any investigational product within 1 month of first dose of STP705.