Gaithersburg, MD, USA and Suzhou BioBay, China, June 15, 2022 — Sirnaomics Ltd. (“Sirnaomics”, stock code: 2257.HK), a leading biopharmaceutical company in discovery and development of RNAi therapeutics, announced the peer-reviewed publication of Phase IIa clinical study results of its lead therapeutic candidate, STP705, for the treatment of skin cancer, in the May 2022 issue of the Journal of Drugs in Dermatology (the “JDD”). The study, titled “Safety and Efficacy of TGF-β1/COX-2 Silencing Therapeutic in Adults with Cutaneous Squamous Cell Carcinoma In Situ,” showed that STP705 was safe and well-tolerated in patients with Cutaneous Squamous Cell Carcinoma In Situ (isSCC).

The key results from the publication indicate that this single-center, open label, dose escalation cohort study evaluated the safety and efficacy of various doses of intralesional injections of STP705, a therapeutic of TGF-β1/COX-2 combined with histidine-lysine polypeptide (siRNA/HKP) nanoparticle silencing, in patients with cutaneous cell carcinoma. The primary endpoint was the proportion of patients with complete histological clearance. Twenty-five patients received STP705 where nineteen of them (76%) achieved histological clearance. In the 30 µg/treatment group and 60 µg/treatment group, 80% and 100% of them achieved histological clearance, respectively. As a result of the study, STP705 appears to be noninvasive, safe and efficacious in treating cutaneous in situ squamous cell carcinoma. The recommended doses for future study of the investigational product are 30 µg/treatment and 60 µg/treatment.

At last fall’s Clinical Dermatology Conference 2021, Brian Berman, MD, PhD, Professor of Dermatology at The University of Miami Miller School of Medicine, a member of the Board of Directors of the American Academy of Dermatology, and the principal investigator of the clinical study of STP705 for treatment of isSCC, gave a presentation on the details of the clinical development and study results. Following his presentation, an audience survey was conducted among 2000+ clinical dermatologists, with questions about whether STP705 fulfilled a need for clinical practices for the treatment of isSCC. The survey results provided a strong favorable opinion regarding the clinical application potential of STP705. Through the Gore Range Capital Skin Health Innovation Competition during the conference, Sirnaomics STP705 was selected as one of the top three finalists.

“A limited number of approved, non-surgical treatments for isSCC currently exist. Our results suggest that STP705 has the potential to be a viable option for patients with skin lesions due to this form of non-melanoma skin cancer, and publication and survey results further validated the clinical application potential of this novel siRNA therapeutic,” said Michael Molyneaux M.D., Executive Director and Chief Medical Officer at Sirnaomics and lead author of the study. “The overexpression of TGF-β1 and COX-2 genes are strongly associated with SCC development, with TGF-β1 having a prominent role in tumor progression. By using RNAi based therapeutics such as STP705 that silence these genes, we have the potential to block the proliferation of isSCC through non-invasive means. This study supports this thesis, and we plan to continue to evaluate 30 µg and 60 µg doses in future studies.”

“The peer-reviewed publication of our Phase IIa STP705 clinical study results for treating isSCC in the JDD, together with strong favorable opinion among the clinical dermatologists, further strengthens our confidence in moving forward with STP705 clinical studies for applications in various types of the non-melanoma skin cancers.” said Patrick Lu, Ph.D., founder, Chairman of the Board, Executive Director, President and CEO of Sirnaomics. “This is a prevalent type of cancer, with over five million new diagnoses in the U.S. each year, and after surgical removal patients can have an increased risk of tumor progression, metastasis, and recurrence as well as risk of infection, hematoma, and scarring. These patients need an alternative, non-invasive treatment option, which is why we are evaluating STP705.”

About Non-melanoma Skin Cancer and Squamous Cell Carcinoma In Situ

Non-melanoma skin cancers (NMSC) are the most common forms of human neoplasia. NMSC constitute a large group of skin cancers that are not melanoma, including squamous cell carcinoma (SCC), basal cell carcinoma (BCC), Extramammary Paget’s Disease (EMPD), Merkel cell carcinoma (MCC), and skin adnexal carcinomas. Among these, BCC and SCC account for the majority of NMSC with more than 5 million newly diagnosed cases estimated to occur in the U.S. every year. Squamous cell carcinoma in situ, also called Bowen disease, is the earliest form of SCC. Along with BCC, SCC is one of two major subtypes of NMSC.

According to Incidence Estimate of Non-melanoma Skin Cancer (Keratinocyte Carcinomas) in the U.S. Population, 2012, the number of new cases of isSCC in the U.S. was 1.3 million in 2020 and is projected to increase to 3.4 million in 2030. In China, according to Chinese Society of Clinical Oncology, the number of new cases of isSCC is 11 thousand in 2020 and is projected to increase to 26 thousand in 2030.

A World Health Organization authorized report from “International Agency for Research on Cancer” (2019) has demonstrated that the number of deaths in 2018 globally for both men and women from NMSC is 65,155, where the mortality of NMSC patients in Asia represents 41.9% of the global total, significantly more than other individual areas.

Surgery is the currently the most common treatment option for the treatment of NMSC. The various forms of surgical modalities carry significant cutaneous adverse events, risk of scar, infection and bleeding. Surgery can also have a significant recurrence rate. As a result, there is a high unmet need for an U.S. Food and Drug Administration (FDA) approved local injection therapy that is safe and effective.

About STP705

Sirnaomics’ leading product candidate, 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. The product candidate has received multiple IND approvals from both the U.S. FDA and Chinese National Medical Products Administration, including treatments of cholangiocarcinoma, non-melanoma skin cancer and hypertrophic scar. STP705 has also received Orphan Drug Designation for treatment of cholangiocarcinoma and primary sclerosing cholangitis. STP705 is currently in five clinical trials for different indications: a Phase IIa for isSCC, a Phase II for BCC, a Phase I/II for keloid scarring, a Phase I/II for hypertrophic scar, and a Phase I for liver cancer (basket).

About Sirnaomics

Sirnaomics is an RNA therapeutics biopharmaceutical company with product candidates in preclinical and clinical stages that focuses on the discovery and development of innovative drugs for indications with medical needs and large market opportunities. Sirnaomics is the first clinical-stage RNA therapeutics company to have a strong presence in both China and the United States, and also the first company to achieve positive Phase IIa clinical outcomes in oncology for an RNAi therapeutics for its core product, STP705. Learn more atwww.sirnaomics.com.

CONTACT:

Michael Molyneaux, MD, MBA

Executive Director and Chief Medical Officer, Sirnaomics

Email: MichaelMolyneaux@sirnaomics.com

Investor Relations:

Nigel Yip

Chief Financial Officer, China, Sirnaomics

Email: NigelYip@sirnaomics.com

US Media Contact:

Alexis Feinberg

Tel: +1 203 939 2225

Email: Alexis.Feinberg@westwicke.com

Asia Media Contact:

Bunny Lee

Tel: +852 3150 6707

Email: sirnaomics.hk@pordahavas.com