With two weeks to go before hearing on whether the preterm birth prevention drug can stay on the market or be withdrawn, the lack of clarity on who will make the ultimate decision may stem from the lengthy duration of the dispute and multiple transitions within FDA’s senior leadership.

The new ALS product is a fixed-dose combo of two ingredients – sodium phenylbutyrate and taurursodiol – that some patients currently are compounding. Amylyx says it will explore ‘all options’ in addressing that, noting its strong IP for Relyvrio, but also committing to access.

A Pink Sheet timeline shows the regulatory highs and lows of AMX0035's path to US approval for treatment of amyotrophic lateral sclerosis.

The single positive Phase II CENTAUR study, along with confirmatory evidence of benefit on long-term survival in the open-label extension, demonstrate substantial evidence of effectiveness, the agency says, acknowledging a level of uncertainty that is acceptable in the disease context.

Launched in part to help resurrect AMX0035’s regulatory prospects, the multiregional PHOENIX study is winding down in the US. There still may be some risk of potential dropouts, however.

In concluding benefits do not outweigh risks in the drug’s current indication, US FDA advisory committee members cite concerns about survival data from the Phase III DUO trial, as well as the drug’s toxicities, safety issues with the PI3K inhibitor class, and the changing treatment landscape for chronic lymphocytic leukemia and small lymphocytic lymphoma.