Targeted Genetics Corporation has achieved its enrolment target of 120 patients in its ongoing phase I/II clinical trial of tgAAC94. The study is designed to assess the safety and potential efficacy of different doses of tgAAC94 administered directly to affected joints of patients with inflammatory arthritis.

tgAAC94 is an investigational therapy that utilizes an adeno-associated virus (AAV) vector to deliver the gene encoding a soluble form of the receptor for ` (TNFR:Fc). The TNFR:Fc protein is a potent inhibitor of tumour necrosis factor-alpha (TNF-alpha), a key mediator of inflammation.

"We are pleased with the rapid pace of enrolment in this study, and believe that it reflects the substantial unmet medical needs of patients with inflammatory arthritis," said H. Stewart Parker, president and chief executive officer of Targeted Genetics. "Interim data suggest that tgAAC94 reduces tenderness and swelling in treated joints in patients whether or not they are taking concomitant systemic TNF-alpha antagonist therapy. Completing enrolment and initial dosing in this trial is an important step in the development of tgAAC94. We expect to present additional interim data from the trial at multiple scientific venues during 2007, and data from the completed study in mid-2008."

In the ongoing phase I/II study, 120 adults were randomised into three dose levels to receive a single intra-articular injection of either tgAAC94 or placebo into the knee, ankle, wrist, metacarpophalangeal or elbow, followed by an open-label injection of tgAAC94 after 12 to 30 weeks, depending on when arthritis symptoms in the target joint meet criteria for re-injection. Following the second injection, all subjects are followed for an additional 30 weeks.

Interim data from the study were reported in February 2007 on 61 subjects randomised into three dose cohorts. The data support the safety and tolerability of single and repeat intra-articular injections of tgAAC94 to affected joints at doses up to 1x10(13) DNase Resistant Particles per milli-liter (DRP/mL) of joint fluid in subjects with and without systemic TNF-alpha antagonists. The data continue to suggest that treatment with tgAAC94 may lead to improvements in signs and symptoms of arthritis in injected joints.

Interim data from this study were also presented at the American College of Rheumatology Annual Scientific meeting in November 2006. Investigators reported that among the first 41 subjects randomised to the two lower doses of tgAAC94 or placebo, 7 of 10 subjects (70%) who received placebo qualified for open label tgAAC94 prior to 30 weeks, in contrast to 16 of 31 subjects (52%) who received tgAAC94. The median time to second injection was 120, 129 and 145 days for subjects who received placebo, tgAAC94 1x10(11) DRP/mL and tgAAC94 1x10(12) DRP/mL, respectively.

Future clinical study design will be based on results from the ongoing phase I/II clinical study and initiation of the next trial is anticipated for the first half of 2008.