OctoPlus Commences United States Phase IIa Study with Locteron for the Treatment of Hepatitis C

OctoPlus N.V. ("OctoPlus" or the "Company") (Euronext: OCTO), the drug delivery and development company, announces today the commencement of patient dosing in a Phase IIa study in the United States with Locteron, its controlled-release formulation of alfa interferon for treatment of chronic hepatitis C (HCV). This study will expand upon the favorable results of the recently completed SELECT-1 Phase IIa study in Europe, which were presented at the Annual Meeting of the American Association for the Study of Liver Diseases (AASLD) conference in November. The study is being conducted under an Investigational New Drug (IND) application filed with the US Food and Drug Administration.

Joost Holthuis, CEO of OctoPlus, comments: "The results presented in November demonstrate Locteron's favorable combination of efficacy and improved tolerability at relatively high doses and we are pleased to expand on these results with this U.S. study. Generating clinical and regulatory experience with Locteron in the United States and making a direct comparison with the current standard of care in HCV will enable us to confidently progress with the clinical development of a best-in-class therapeutic for chronic hepatitis C patients."

Design of the United States Phase IIa study

The United States Phase IIa "PLUS" trial will evaluate up to 56 patients with chronic hepatitis C. The PLUS trial will evaluate safety, tolerability, pharmacokinetics and viral kinetics of Locteron and will provide U.S. investigators first-hand experience with the product. Locteron doses to be evaluated in the trial include 320 mcg, the lowest dose in the SELECT-1 study to show favorable viral response, and 640 mcg, the highest dose of Locteron studied to date.

The first phase of the PLUS trial will involve four weeks of treatment and will compare the 320 mcg dose of Locteron to PegIntron, each in combination with daily ribavirin, in a total of 16 chronic hepatitis C patients who have failed prior treatment. The second phase of the trial will also include four weeks of treatment and will compare the 640 mcg dose of Locteron to PegIntron, each in combination with daily ribavirin, in a total of 16 patients who have failed prior treatment. The final phase will evaluate 12 weeks of treatment of 24 treatment-naive patients with the genotype-1 variant of the virus, with patients randomized to receive either the 320 mcg dose of Locteron, the 640 mcg dose of Locteron, or PegIntron, each in combination with daily ribavirin.

Locteron clinical overview

Locteron is designed to be a best-in-class therapeutic for patients with chronic hepatitis C, with the potential to reduce side effects, improve patient compliance, and provide a more convenient once-every-two-week dosing schedule compared with current therapies.

The SELECT-1 Phase IIa study results presented in November 2007 show a strong anti-viral response and patients receiving Locteron experienced side effects that were less frequent and less severe than those previously reported in clinical trials for the currently marketed pegylated interferons and for a development-stage product, Albuferon. Successful completion of the PLUS trial will prepare for dosing of Locteron for longer durations and in previously underserved patient populations.

OctoPlus and its co-development partner Biolex Therapeutics plan to commence SELECT-2, a Phase IIb trial with Locteron, in the fourth quarter of 2008. The 12-week results of the Phase IIb trial will be used as the basis for dose selection for the commencement of the Phase III development program.

About Locteron

Locteron combines OctoPlus' proprietary PolyActive(TM) drug delivery technology with BLX-883, a recombinant alfa interferon produced by OctoPlus' co-development partner Biolex Therapeutics in its patented LEX SystemSM. Locteron is produced in OctoPlus' cGMP manufacturing facilities in Leiden, the Netherlands.