Despite Failed Phase 3 Study, FDA Staff Says Biogen's ALS Drug May Have Clinical Benefit

FDA's Peripheral and Central Nervous System Drugs Advisory Committee will virtually meet on Wednesday, March 22, to discuss Biogen Inc's BIIB ALS drug tofersen.
FDA staff, citing a briefing document, said Biogen's investigational ALS drug might have a "clinical benefit" on a rare and aggressive form of the disease, despite failing a broader late-stage clinical trial last year.
"Despite the notable limitations of a failed study and the many post hoc exploratory analyses conducted after [the Phase III trial], the Division considers that the data may suggest a treatment effect of tofersen in SOD1-ALS," the FDA wrote. "This is a very rare and devastating disease; therefore, it is of utmost importance that we give full consideration to all available data."
Tofersen did not achieve the primary goal of its Phase 3 VALOR trial, failing to prove it could slow SOD1-ALS patients' functional decline better than a placebo. Biogen said the p-value for the primary endpoint was p=0.97.
"This is a situation where there is a negative clinical study that failed to show a statistically significant treatment effect in the prespecified primary analysis population," the report says.
It notes, however, that the study was limited in its ability to determine whether the drug affected the overall population because of how it was designed.
At the same time, the data indicate that targeted drug use was shown to reduce "a biomarker that is correlated with disease progression and prognosis in patients with ALS."
The FDA accepted Biogen's application for full approval of tofersen in July. Last October, the agency extended its application review by three months, with a PDUFA date of April 25.
Price Action: BIIB shares closed at $267.91 on Monday.