Isis rolls into Phase III with an orphan drug as it waits on Biogen

Isis Pharmaceuticals ($ISIS) has kicked off a Phase III trial on ISIS-SMNrx, a treatment for the rare spinal muscular atrophy, moving forward with the orphan drug as partner Biogen Idec ($BIIB) considers whether to take the plunge on the program.

The drug is an antisense treatment designed to boost the production of the protein SMN, a lack of which imperils the nerve cells responsible for muscle growth and function, leading to the deadly SMA. The company is now recruiting about 110 infants with disease in a Phase III study, planning to test how well ISIS-SMNrx can improve survival and forestall the need for ventilation, and the biotech said it's on schedule to launch a second late-stage trial this year on older children with SMA.

The treatment is one of four antisense drugs covered by a $299 million pact with Biogen signed in 2012. Under the agreement, Isis handles discovery and early development, while Biogen has the option to buy into each program until it reaches a certain stage of development. For ISIS-SMNrx, the deadline is the completion of a Phase III trial, giving the Big Biotech about 13 months to make up its mind.

For now, Isis is pointing to new data from an open-label Phase II study on ISIS-SMNrx, in which infants getting a 6 mg dose of the drug recorded a median event-free age of 14 months and those getting 12 mg lived an median of 11.6 months before enduring any complications. The median for untreated patients is 10.5 months, according to Isis.

In Phase II results unveiled earlier this year, the orphan therapy was well-tolerated and charted dose-dependent increases in muscle function, Isis said. At 9 months, patients on the highest dose improved their muscle function by an average of 3.7 points on the Hammersmith Functional Motor Scale-Expanded, which measures changes in function in SMA sufferers, according to the company.

Isis Senior VP C. Frank Bennett

"The consistency of the increases in muscle function scores across different SMA patient populations, including both children and infants with SMA, and the dose- and time-dependency of these increases is encouraging," Isis Senior Vice President C. Frank Bennett said in a statement. "The observation of increases in SMN protein in the spinal cord in tissues analyzed from ISIS-SMNRx-treated infants suggest that ISIS-SMNRx is acting by the mechanism of action through which it was designed to act."

- read the statement

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