A Study to Evaluate Safety, Efficacy of Intralesional Injection of STP705 in Patients With isSCC

This is a two-part, double-blind, randomized, placebo-controlled study designed to evaluate safety and efficacy of various doses of STP705 administered as an intralesional injection in subjects with isSCC. A total of up to 100 eligible subjects will be enrolled. Enrolled subjects will be randomly allocated to receive STP705 or placebo injection once weekly for 6 weeks. After 6 weeks, the lesion will be excised. In part 1 (dose ranging study): 40 subjects will be randomized to receive 1 of the 3 STP705 doses or placebo. An interim analysis will be done after all subjects have completed end of treatment (EOT) visits to determine 2 selected dose levels of STP705 to be used in part of the study. In part 2: 60 additional subjects will be randomized to receive 1 of the 2 selected doses (from part 1) or placebo. In both parts at the End of Treatment (EOT), the lesion will be excised.