Arrowhead Research Corporation (NASDAQ: ARWR), a biopharmaceutical company developing targeted RNAi therapeutics, today announced that it completed enrollment in a Phase 1 clinical trial of ARC-520, its RNAi-based candidate against chronic hepatitis B virus infection. Initial data indicate that ARC-520 is generally safe and well tolerated at all six dose levels studied, enabling the company to proceed with plans to initiate a Phase 2a pilot efficacy study in chronic HBV patients. “We are very pleased with these results and the pace at which we were able to complete the Phase 1 study. This positive readout on safety and tolerability of ARC-520 and the Dynamic Polyconjugate (DPC) delivery platform has broad implications for Arrowhead. It gives us additional confidence as we move into an upcoming Phase 2a study and we believe it represents a key de-risking event for expanding our pipeline of RNAi therapeutics based on the DPC platform,” said Christopher Anzalone, Ph.D., President and Chief Executive Officer. The Phase 1 trial was designed to characterize the safety profile of ARC-520 across a range of doses and evaluate pharmacokinetics. It is a single-center, randomized, double-blind, placebo-controlled, single dose-escalation, first-in-human study of ARC-520 administered intravenously to healthy adult volunteers. All subjects have been dosed and received either placebo or ARC-520 in doses ranging from 0.01 mg/kg to 2 mg/kg. The study was planned to enroll 36 subjects in six cohorts of six subjects each, with 2 subjects receiving placebo and 4 receiving ARC-520. The study successfully enrolled all 36 subjects (24 received ARC-520, 12 placebo) at a single center in Melbourne, Australia. All subjects received their full, assigned dose and there were no discontinuations for adverse events or otherwise. Based on pre-clinical studies, including GLP toxicology, it is expected that if any clinically significant or dose-limiting toxicities were to occur, they would be observed within the first 24-48 hours after administration, and would be apparent in elevations in blood chemistries. The anticipated organs of interest for potential toxicity and the resultant chemistries are liver (ALT), kidney (creatinine, urea), and muscle (CK, AST, LDH, Troponin I). In this Phase 1 study, laboratory results have not indicated any organ toxicity involving the liver, kidney, or muscle in any subject.