On February 23, 2022 Sirnaomics Ltd. ("Sirnaomics", stock code: 2257.HK), a leading biopharmaceutical company in discovery and development of RNAi therapeutics, reported interim data from a Phase II clinical trial of STP705, a siRNA (small interfering RNA) therapeutic, for the treatment of cutaneous basal cell carcinoma (BCC) (Press release, Sirnaomics, FEB 23, 2022, View Source [SID1234608921]). The interim data, which examines results from three cohorts with 15 total subjects, shows a dose response with complete response, as well as improved or stable cosmetic result with no significant cutaneous skin reactions. Interim data also suggests a favorable safety profile as there are no drug related adverse events (AEs) or serious adverse events (SAEs).
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The Phase II open label, dose escalation study is designed to evaluate the safety, tolerability and efficacy of various doses of STP705 administered as localized injection in patients with BCC. The primary endpoint is to determine the proportion of participants with a complete response of treated BCC at the end of treatment, which is defined as the absence of detectable evidence of BCC tumor cell nests. The secondary endpoints are to determine the safe and effective recommended dose of STP705, and an analysis of biomarkers common to BCC formation pathway, including TGF-β1 and COX-2.
The interim analysis is comprised of three dose escalation cohorts ranging from 30μg to 90μg with five patients in each group, for a total of 15 patients enrolled in the trial so far. Participants received injections of STP705 once a week for up to six weeks. In cohorts B and C, which received doses of STP705 at 60µg and 90µg respectively, three out of five patients achieved a complete response. Cohort A, which received a 30µg dose, saw a complete response in one out of five participants.
"This interim data indicates that STP705 achieved therapeutic responses from patients with BCC, in addition to the positive readouts from patients with SCC, which further demonstrates our leadership in developing RNAi-based treatments for skin cancers," said Patrick Lu, Ph.D., the founder, Chairman of the Board, Executive Director, President and CEO of Sirnaomics. "We look forward to seeing the results of our next data readout in this Phase II study with the rest of participant cohorts, which will give us more insights into the efficacy of STP705 as we seek to move this important therapeutic candidate forward."
"These encouraging interim results from the Phase II clinical trial of STP705 suggest that we are on a path to potentially offer a treatment for patients with BCC that would be an alternative to surgical excision of these lesions," said Michael Molyneaux, M.D., Executive Director and Chief Medical Officer at Sirnaomics. "There is an unmet need for non-surgical treatments for various types of nonmelanoma skin cancers that reduce scarring and achieve high rates of complete response, which we have begun to see in this arm of the study."
The remaining portion of the Phase II study will include two additional cohorts of five subjects with dosing of 120μg and 180ug, for a total of 25 participants in the clinical trial. Additional information about this clinical trial is available at clinicaltrials.gov using the identifier: NCT04669808.
About Basal Cell Carcinoma
BCC is a type of nonmelanoma skin cancer (NMSC) that is associated with exposure to ultraviolet radiation from the sun. BCC usually does not spread to other parts of the body therefore the vast majority is pre-metastatic. According to a China Insights Consultancy report, the estimated metastasis rate of BCC ranges from 0.0029% to 0.55%, and common metastatic sites are regional lymph nodes, lungs, bones, skin, and liver. Standard treatments for BCC are standard surgical excision, Mohs micrographic surgery, topical cream treatments, cryosurgery, laser therapy, electro-desiccation and radiation therapy. Various forms of surgical modalities carry significant cutaneous adverse events, risk of scar, infection, and bleeding. Currently, there are two drugs approved by U.S. FDA for premetastatic BCC patients, which can cause skin reactions in some patients.
Treatment of BCC with STP705 shows benefits in cosmetic appearance, especially for patients with lesions on the head, face or neck, and clinical results demonstrate that STP705 has a high complete response compared with currently available topical treatments.
About STP705
Sirnaomics’ core product candidate, STP705, is a dual TGF-β1/COX-2 inhibitor. TGF-β1 and COX-2 are known as gatekeeper targets for oncology and fibrosis disease drug development. TGF-β1 regulates a broad range of cellular processes, including cell proliferation, differentiation, apoptosis, extracellular matrix production, angiogenesis, inflammation and immune response, while COX-2 is a proinflammatory and proliferative mediator. STP705 leverages our PNP delivery platform in a locally administered formulation for direct administration to diseased tissue. Sirnaomics is developing STP705 for non-melanoma skin cancer, including squamous cell carcinoma in situ (isSCC), skin BCC, dermal fibrosis, and solid liver tumors.