Codiak BioSciences, Inc. announced the initiation of patient dosing in its Phase 1 clinical trial of exoASO-STAT6, an engineered exosome precision medicine candidate designed to selectively deliver antisense oligonucleotides to disrupt STAT6 signaling in tumor associated macrophages (TAMs) and induce an anti-tumor immune response. exoASO-STAT6 is Codiak's third clinical program and the first to evaluate a systemically administered exosome-based drug candidate.
The Phase 1 clinical trial will evaluate the safety, tolerability, biomarkers and preliminary anti-tumor activity of exoASO-STAT6 in patients with advanced hepatocellular carcinoma (HCC), patients with liver metastases from primary gastric cancer and colorectal cancer (CRC). The study is anticipated to enroll patients across four cohorts at sequentially escalating dose levels, with subjects in the initial cohorts receiving biweekly exoASO-STAT6 administered intravenously over the course of 28 days. Ultimately the trial may enroll up to 30 patients. Initial Phase 1 data are expected in the first half of 2023. TAMs promote tumor growth by exhibiting an immune suppressive M2 phenotype. Reprogramming TAMs toward a pro-inflammatory M1 phenotype may be a compelling approach to induce anti-tumor immunity. The M2 phenotype is controlled by key transcription factors such as STAT6, which have proven difficult to drug selectively in TAMs using prior approaches. Codiak plans to initially develop exoASO-STAT6 for primary cancers of the liver, where STAT6 expression has been correlated with poor survival.
In multiple in vivo preclinical studies, exoASO-STAT6 demonstrated potent single agent activity, including >90% tumor growth inhibition and 50-80% complete responses. In HCC models, exoASO-STAT6 induced significant knockdown of STAT6 mRNA, attenuated tumor growth and induced complete remission of tumor lesions in 50% of mice. This anti-tumor activity was enhanced (75% complete remissions) when exoASO-STAT6 was administered with anti-PD1 antibodies. The monotherapy activity was accompanied by remodeling of the tumor microenvironment including significant expansion of M1-like macrophages and induction of an adaptive anti-tumor immune response, enabling tumor elimination. Codiak's proprietary engEx Platform is designed to enable the development of engineered exosome therapeutics for a wide spectrum of diseases and to manufacture them reproducibly and at scale to pharmaceutical standards. By leveraging the inherent biology, function and tolerability profile of exosomes, Codiak is developing engEx exosomes designed to carry and protect potent drug molecules, provide selective delivery and elicit the desired pharmacology at the desired tissue and cellular sites. Through its engEx Platform, Codiak seeks to direct tropism and distribution by engineering exosomes to carry on their surface specific targeting drug moieties, such as proteins, antibodies/fragments, and peptides, individually or in combination. Codiak scientists have identified two exosomal proteins that serve as surface and luminal scaffolds. By engineering the exosome surface or lumen and optimizing the route of administration, Codiak aims to deliver engEx exosomes to the desired cell and tissue to more selectively engage the drug target, potentially enhancing the therapeutic index by improving potency and reducing toxicity.