Despite FDA Delay, Advocates Hopeful for New Genentech MS Drug

Xconomy San Francisco — 

Of the 15 FDA-approved therapies for multiple sclerosis, none work on a rare form of the disorder that leads to a steady and sometimes rapid decline. Genentech is awaiting FDA action on its experimental drug for this “primary progressive” form of the disease, and a new study published today may strengthen its case for approval.

If Genentech, a division of Swiss pharma giant Roche, gets the nod, it would bring to market the first approved drug for the more severe form of MS.

An FDA decision on the drug that was expected in late December has been pushed out to March. New clinical trial results published online Wednesday in the New England Journal of Medicine may bolster Genentech’s chances.

“This is the first drug to show a significant effect in slowing disability progression in a phase 3 trial in primary progressive multiple sclerosis, and therefore the trial represents a landmark study in the field,” the Journal said in an editorial.

Though MS affects the body’s nerves, it is caused by the immune system. For reasons that aren’t fully understood, the body’s immune cells attack myelin, the fatty substance that covers nerve cells. The MS treatments already approved for treating MS dampen this attack by targeting the body’s T cells. Genentech’s drug ocrelizumab (Ocrevus) works in a different way by targeting the immune system’s B cells.

Genentech studied its drug in three Phase 3 clinical trials. Two trials enrolled patients who have relapsing-remitting form of the disease, in which patients partially recover but then go on to experience additional attacks. Compared against a group of patients treated with interferon beta-1a, the standard of care for this form of MS, the relapse rate for patients treated with the Genentech drug was lower by 46 percent in one trial and 47 percent in the other.

A third trial studied patients who have the primary progressive form of MS. According to those trial results, the disability progression of this form of the disease was 25 percent lower in patients who received the Genentech drug compared against those who were given a placebo. Furthermore, the drug also reduced the volume of brain lesions, according to trial results. Genentech is seeking FDA approval on ocrelizumab in both the relapsing and the progressive forms of MS. While the Journal acknowledged the promise shown by the trial results, it also cautioned that like any drug that suppresses the immune system, ocrelizumab may make patients more susceptible to infections.

Tim Coetzee, chief advocacy, services and research officer for the National MS Society, says the study is important because it validates the B cell approach. (Genentech is one of the drug companies that are corporate sponsors of the National MS Society.) Coetzee recalls just one other company, EMD Serono, taking a B cell-targeting therapeutic into clinical trials. That drug failed, though Coetzee says other B cell MS therapies are in earlier stages of development.

For patients, the Genentech drug may offer a more convenient way to receive treatment for MS. Ocrelizumab is dosed every six months, unlike some MS drugs that must be administered daily or three times a week. Many patients with the relapsing-remitting form of MS need to try different therapies before finding the one that works, Coetzee says. This drug might offer them one more choice, and a first choice for patients who have the progressive form of MS.

“It’s the first indication that there is an agent that can modify the disease and potentially be a treatment for primary progressive MS,” Coetzee says. “For individuals with this form of the disease, it’s a tremendous source of hope.”

Genentech says the FDA extended the approval timeline after the company submitted additional information about the drug’s manufacturing process. The regulator needs more time to review that information, Genetech says. The delay has nothing to do with ocrelizumab’s safety or efficacy, according to the company.

The new target date for an FDA decision on the drug is March 28.

Photo of Genentech sign by Rajiv Patel used under a Creative Commons license.