On December 3, 2020 Sirnaomics, Inc., a biopharmaceutical company engaged in the discovery and development of RNAi therapeutics against cancer and fibrotic diseases, reported that the company has received feedback from the U.S. Food and Drug Administration (FDA) and may now proceed with a planned Phase I clinical study of its leading drug candidate, STP705, for treatment of multiple types of liver cancer (Press release, Sirnaomics, DEC 3, 2020, View Source [SID1234572152]).
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The FDA has provided valuable feedback on the company’s proposed trial design for a "Phase 1 Multicenter, Open-Label, Dose Escalation Study and Dose Expansion Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Anti-Tumor Activity of STP705 Administered Intratumorally in Cholangiocarcinoma, Hepatocellular Carcinoma or Liver Metastases in Subjects With Advanced / Metastatic or Surgically Unresectable Solid Tumors Who Are Refractory to Standard Therapy." The first patient is expected to be enrolled in the study in the first quarter of 2021. STP705 is a small interfering RNA (siRNA) therapeutic that utilizes a proprietary polypeptide nanoparticle (PNP)-enhanced delivery system to inhibit expression of TGF-β1 and COX-2 in targeted tissue and cells. Preclinical animal models have demonstrated its effective anti-tumor activity for treatments of cholangiocarcinoma and hepatocellular carcinoma.
"Receiving the required feedback from the FDA now permits us to proceed with this Phase I study that represents an important step forward in demonstrating the broader clinical utility of our siRNA therapeutic candidates," said Patrick Y. Lu, PhD, Sirnaomics’ Founder and CEO. "Liver cancer treatment remains a critical unmet need globally and especially in Asian countries. Our clinical strategy leveraging STP705’s FDA Orphan Drug designation for the treatment of cholangiocarcinoma and hepatocellular carcinoma will potentially be highly beneficial to patients suffering these life threatening diseases in both the US and Asia. We are anticipating that this clinical study will contribute to the expanding clinical evidence supporting extensive therapeutic potential of STP705 against various cancers."
"Liver cancer continues to be a devastating disease for patients with high mortality and high unmet medical need," stated Michael Molyneaux, MD, Sirnaomics’ Chief Medical Officer. "This disease fits with Sirnaomics mission to bring lifesaving drugs to patients with severe debilitating medical illness. We hope to gain important insight into the potential safety and efficacy of STP705 in this Phase I trial and we expect to build on the data from this study to expand into other oncology indications."
About Liver Cancer
Liver cancer is a global health problem, with liver neoplasms representing the second-most frequent cause of cancer-related death. There are many different types of liver cancers including hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), liver angiosarcoma, hepatoblastoma and others. Additionally, liver is a highly metastasis-permissive organ. It is the most frequently afflicted organ by metastasis and liver metastases are much more common than primary hepatic tumors. The distinctive biology of the liver renders it intrinsically susceptible to metastases. The true prevalence of liver metastasis is unknown, but between 30% and 70% of patients dying of cancer have liver metastases and most patients with liver metastases will die of their disease.
STP705 and Liver Cancer
Over expressions of TGF-β1 and COX-2 have been well-characterized as playing key regulatory roles in tumorigenesis. TGF-β is produced by different liver cells and is demonstrated to induce tumor cell migration and survival. TGF-β has been found to be overexpressed in metastatic HCC tissues. Overexpression of TGF-β is generally accepted to be associated with metastasis and poor prognosis. COX-2 is reported to be highly expressed in cancer stem cells and promotes cell migration in HCC cell lines. Additionally, inhibition of COX-2 suppresses cell migration and induces apoptosis. As such TGF-β1 and COX-2 are excellent therapeutic targets for treatment of liver cancer.
STP705 is composed of two siRNA oligonucleotides targeting TGF-β1 and COX-2 mRNA respectively and formulated in nanoparticles with a proprietary Histidine-Lysine Co-Polymer (HKP) peptide. Each individual siRNA has demonstrated the ability to inhibit the expression of their target mRNA and combining the two siRNAs produces a synergistic effect that diminishes pro-fibrogenic, pro-inflammatory, and pro-tumorigenic factors. Sirnaomics has completed numerous pre-clinical studies that demonstrate that inhibition of TGF-β1 and COX-2 is expected to result in the inhibition of tumor growth and provide an alternative approach for the treatment of various liver cancers. Molecular analyses of the effects of administering the combination demonstrated that the inhibition of these targets had effects on downstream gene products associated with numerous oncology targets. Additional immunohistochemistry and image analyses of the liver and tumor tissues demonstrated that animals treated with STP705 resulted in increased CD4+ and CD8+ T cell infiltration within the tumor microenvironment. Using STP705 for treatments of hepatocellular carcinoma and cholangiocarcinoma have been designated as Orphan Drug indications by U.S. FDA. STP705 has also been evaluated in a Phase IIa clinical trial for treatment of Non-melanoma skin cancer.