Project 2: Hepatocyte-targeted HCC chemoprevention with Anillin knockdown

PROJECT 2 SUMMARY Hepatocellular carcinoma (HCC) is the fastest growing cause of cancer-related death in the U.S. and a leading cause of death in patients with cirrhosis. Once HCC develops in a cirrhotic liver, it is difficult to cure due to its refractory nature and frequent recurrence after treatment, with 5-year survival under 20% and an incidence-to-mortality ratio near one. Locoregional therapies, including chemoembolization, radioembolization and local ablation, are the most common treatments in practice; however, recurrence rates approach 50-70% within 2 years even among those with durable responses. This is because a “field defect” from cirrhosis results in frequent de novo tumor formation. Treatments for recurrent HCC have decreased objective responses and increased risk of liver dysfunction, leading to short median survival. Therefore, tertiary prevention of HCC recurrence would be an ideal approach to reduce mortality from HCC, but this remains an unmet need. To identify novel de novo HCC prevention strategies, we have focused on physiologic mechanisms that naturally exist to suppress liver cancer. Incomplete cytokinesis is a normal physiologic mechanism that drives the polyploidization of hepatocytes, a cellular state that is widespread even in healthy livers. We discovered that knockdown or deletion of a cytoskeletal scaffolding protein called Anillin (ANLN) can suppress hepatocyte cytokinesis and induce polyploidization. Mouse genetic studies using transient ANLN knockdown allowed us to discover that increasing the number of polyploid hepatocytes (containing whole number genome duplications) protects the liver from malignant transformation. In addition, siRNA studies of long-term ANLN knockdown, performed in partnership with our industry partner Alnylam, have shown that prolonged cytokinesis inhibition is also protective against HCC development in multiple mouse liver cancer models. Importantly, ANLN inhibition does not disrupt liver function or regeneration, even when confronted with the kind of chronic liver injury seen in cirrhosis patients. Given that a large fraction of normal human hepatocytes are polyploid, it is likely an evolutionarily selected mechanism of stress adaptation against carcinogenesis. We seek to establish clinical use of ANLN mRNA silencing (siRNAs) to prevent recurrence of de novo tumors in cirrhotic HCC patients after locoregional therapies. By leveraging a clinically established siRNA strategy, we aim to clinically translate an innovative approach based on the basic science discovery connecting ANLN inhibition and HCC development. Toward this goal, we will establish pharmacodynamic biomarker assays (Aim 1), perform late-stage preclinical assessments in humans tissues and mouse models (Aim 2), and initiate a phase 1 clinical trial testing safety and dosing of ANLN siRNA in the context of locoregional HCC treatments (Aim 3).