Antisense to resume MS phase IIa trial

Melbourne's Antisense Therapeutics (ASX:ANP) has been granted approval to restart the phase IIa trial of its antisense compound ATL1102 for patients with relapsing remitting multiple sclerosis.

Antisense has received ethics committee approval from the University of Essen in Germany, the primary trial site for the trial, and patient enrolment and dosing are expected to commence in February/March.

Another eight trial centres in Germany will be initiated in the coming months. The treatment and patient monitoring stages of the 80-patient trial are expected to be completed by the end of 2006, assuming patient recruitment proceeds at the anticipated rate.

"We are very pleased," said Antisense CEO Mark Diamond. "The whole team has worked really hard to get the compound back into clinical trials and we are now back on track."

In March 2005, Antisense voluntarily halted its Phase IIa trial of ATL1102 in MS patients, in the wake of a decision by Biogen Idec and Elan Corp to halt trials of their MS drug Tysabri after two patients were reported to have developed a specific type of viral infection leading to a rare, deadly disease of the central nervous system, progressive multifocal leukoencephalopathy (PML).

Antisense's drug has a different mechanism to Tysabri, but has the same target. The Melbourne company convened an advisory group of relevant experts to consider the potential development paths for ATL1102 in this disease, in light of safety issues associated with of Biogen Idec and Elan Corp's decision to halt the trial.

At the end of August 2005 the Antisense advisory board found that "the risk of PML developing in patients exposed to ATL1102 in the proposed eight-week phase IIa dosing clinical trial is considered to be minimal". It recommended stepping up monitoring of trial patients "to further minimise any risk potential that may exist for the development of PML to help gain a better understanding of the drug's safety profile."

The phase IIa trial of ATL1102 will assess the activity and safety of the drug in MS patients. Apart from the addition of the suggested safety parameters, the trial design and clinical assessment remains the same as the initial phase IIa trial which commenced in December 2004.

ATL1102 is a second-generation antisense inhibitor of an immune system protein called VLA-4 and is designed to block the synthesis of VLA-4 which is known to play a part in both the onset and progression of multiple sclerosis. ATL1102's mechanism of action in blocking VLA-4 is different to other drugs in development that target VLA-4 (including the monoclonal antibody Tysabri) and represents novel therapeutic approach to the treatment of MS.

Safety evaluation

Following the suspension of Tysabri in February 2005, Biogen and Elan launched a safety evaluation of more than 3000 Tysabri patients. In October the companies completed the safety evaluation and findings "yielded no new confirmed cases of PML beyond the three previously reported". The firms presented the FDA with new safety and efficacy data as well as a revised label and risk management plan. The FDA is expected to rule on the application by the end of March.

"Both companies' share prices have risen significantly based on the positive news of the sBLA being accepted," noted Antisense CEO Mark Diamond.

"We hope that the resumption of our trials will have a similar effect. We were around 12-13 cents per share prior to our decision to halt the trials -- we have a long way to go to bring the share price back to that value, but the response from the market today has been very pleasing."

Antisense shares opened today at 0.037 cents and rose to 0.055 cents in morning trade. At time of writing shares were trading at 0.048 up 50 per cent