Reports that a potential blockbuster drug for multiple sclerosis, Tysabri, could be back on shelves later this year appear to have given a boost to Melbourne company Antisense Therapeutics (ASX:ANP), which is also developing an MS drug.

A safety study for Tysabri, developed by Irish company Elan Pharmaceuticals and US company Biogen Idec, has found no new confirmed cases of the brain disease that prompted the drug to be pulled off the shelf in February.

Antisense Therapeutics' share price jumped from AUD$0.044 on Tuesday to $0.06 yesterday, prompting a 'please explain' to the Melbourne company from the Australian Stock Exchange.

"It is likely that the reason for the increase in price and trading volume of Antisense Therapeutics'; shares is [the positive Tysabri news], which has likely been interpreted as positive news for the prospects of Antisense Therapeutics' MS drug ATL1102," the company told the ASX.

Antisense halted a phase IIa trial of ATL1102 after Tysabri was pulled from the market. The Antisense drug is different from Tysabri, which is a monoclonal antibody, but targets the same immune system protein as Tysabri.

The company said it was examining the Tysabri safety study and would weigh its options for ATL1102 accordingly.

Antisense's shares are currently in a trading halt pending an announcement.