Arrowhead Issues Phase 1 Data on ARC-520 at HepDART '13

Arrowhead Research Corporation (NASDAQ: ARWR), a biopharmaceutical companydeveloping targeted RNAi therapeutics, today announced that COO and Head ofR&D, Bruce Given, M.D., presented data on the Phase 1 clinical study ofARC-520, the company's clinical candidate for the treatment of chronichepatitis B infection, at the HepDART 2013 conference being held on The BigIsland, Hawaii. New data including pharmacokinetics (PK) and adverse event(AE) attribution presented today in a poster and in an oral presentationtomorrow, support the previous findings that ARC-520 appears to be generallysafe and well-tolerated at all six dose levels studied.The Phase 1 study was designed to characterize the safety profile of ARC-520across 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 adultvolunteers. 36 subjects have been enrolled in 6 groups randomized at a ratioof 2:1 to receive ARC-520 or placebo: Placebo (n=12), ARC-520 0.01 mg/kg(n=4), 0.1 mg/kg (n=4), 0.3 mg/kg (n=4), 0.6 mg/kg (n=4), 1.2 mg/kg (n=4), and2.0 mg/kg (n=4). The placebo group included 7 male and 5 female subjects withaverage of 28.1 +/- 9.6 years. The treatment group included 12 male and 12female subjects with average age of 26.9 +/- 6.7 years. Subjects were admittedto the unit overnight pre-dose and vital signs, telemetry, ECGs, safety labs,PK, and adverse events were monitored for 24 hours post-dose. Return visitsoccurred for repeat safety evaluations and recording of adverse events at 48hrs, 72 hours, day 7, day 14 and day 28 post dosing.Preliminary results from the phase 1 clinical study of ARC-520 indicate thatto date there have been no serious AEs, no dose limiting toxicities, nodiscontinuations, and a modest occurrence rate of AEs with no dose relatedincrease in frequency or severity, with the possible exception of mildlightheadedness which occurred in two subjects in the 2 mg/kg dose group.There were no general differences observed or findings rated clinicallysignificant on vital signs, ECGs, physical examinations, or clinicallaboratories in the ARC-520 groups relative to placebo. Adverse eventfrequency and severity did not differ between placebo and ARC-520, with 75% ofboth treated and placebo subjects reporting mild or moderate AEs. There was alow occurrence rate of abnormal laboratory tests, with no observedrelationship to timing or dose. PK results appear to indicate that C[0](equivalent to C[Max]) and AUC[0-∞] increase linearly with dose (r^2=0.984).The Phase 1 study has thus demonstrated that a single intravenousadministration of ARC-520 appears to be safe and well tolerated up to andincluding a dose of 2 mg/kg, the highest dose tested. A copy of the posterpresentation is available on the Presentations and Events page of Arrowheadwebsite at http://www.arrowheadresearch.com/presentations.