The randomized, double-blind, placebo-controlled study will evaluate the safety and efficacy of intralesional injection of STP705 in 100 adult patients with squamous cell carcinoma in situ.

Sirnaomics, Inc. is initiating a Phase 2b study of STP705 for the treatment of squamous cell skin cancer.

STP705 is a siRNA (small interfering RNA) therapeutic that takes advantage of a dual-targeted inhibitory property and polypeptide nanoparticle (PNP)-enhanced delivery to directly knock down both TGF-β1 and COX-2 gene expression. It has received multiple IND approvals from both the US FDA and Chinese NMPA, including treatments of cholangiocarcinoma, nonmelanoma skin cancer and hypertrophic scar. STP705 has also received Orphan Drug Designation for treatment of cholangiocarcinoma and primary sclerosing cholangitis.

The randomized, double-blind, placebo-controlled study will evaluate the safety and efficacy of intralesional injection of STP705 in 100 adult patients with squamous cell carcinoma in situ (isSCC). This is a two-part dose escalation trial; in the run-in period, the 30 ug and 60 ug dosing regimens from the Phase 2a study of STP705 will be further evaluated, in addition to a third new dose level. The second part of the trial will further evaluate the two most efficacious dosing regimens. The primary endpoint of this trial is the proportion of participants with histological clearance of treated isSCC lesion at the end of treatment. Histological clearance will be defined as the absence of detectable evidence of isSCC tumor cell nests as determined by central pathology review.

"In the recently concluded Phase 2a clinical trial of STP705 in isSCC, a high rate of patients achieved histological clearance in a dose dependent manner, which is the gold standard for skin cancer," says Patrick Lu, PhD, the founder, President and CEO of Sirnaomics, in a news release. "As we initiate the Phase 2b trial, we are hopeful to learn more about the potential of this non-surgical, non-invasive treatment for common non-melanoma skin cancer, and more broadly the promise of RNAi therapeutics in oncology."  

"isSCC continues to be a disease with high unmet therapeutic need where surgery is still considered the only viable treatment option for many patients," adds Michael Molyneaux MD, Chief Medical Officer of Sirnaomics. "We hope to build on the success we have seen in the Phase 2a study, where we achieved 90% histological clearance rates in the 30 ug and 60 ug dosing groups. We anticipate having an interim data readout late second half of 2021 that will guide our clinical development for this indication."