INCY, MIRM Slip Into FDA’s Weekend Decision Date On Shared Rare-Disease Pill

• Zilurgisertib is meant to quiet ALK2, a signal that is overactive in fibrodysplasia ossificans progressiva, or FOP.
• For Mirum, an approval would add another commercial product.
• For Incyte, built on Jakafi and the skin cream Opzelura, an approval would mean a milestone payment and royalties.

Shares of Incyte (INCY) and Mirum Pharmaceuticals (MIRM) both eased on Friday after opening higher as traders waited for a weekend ruling from U.S. regulators on their shared rare-disease pill zilurgisertib.

INCY opened up about 1% at about $126, and later traded in the low-$123s, leaving the roughly $25 billion company modestly lower. After a mid-September bounce to $127.62, the stock has given back some of those gains heading into the decision. The stock is up about 1% this month.

Mirum, the smaller company that now owns the commercial rights to the drug, opened near $90 and later traded in the high-$88s. The $5.8 billion stock has already given back a mid-September bounce and sits well below its roughly $130 52-week high. The stock is on track for clocking its third week in the red, if the losses hold.

What The FDA Will Decide On Saturday

The Food and Drug Administration’s target date is Saturday, September 26, for zilurgisertib, a once-daily pill for fibrodysplasia ossificans progressiva, or FOP, in patients 12 and older. The review is on a priority basis. FOP is an ultra-rare genetic disease in which muscle and other soft tissue slowly turn into bone, locking joints and cutting mobility. Roughly 400 people in the United States and about 900 worldwide have a diagnosis.

The filing rests on a mid-stage study. Sixty-three teens and adults took a 100 mg daily pill or a dummy tablet for 24 weeks. One person on the drug formed a new extra bone growth (3.1%), versus five on placebo (16.7%). That 81% drop missed the usual statistical cutoff. A second measure was clearer: the total size of new growths fell by more than 99% versus placebo.

Leerink said in June that the volume result may still be enough for a September 26 approval even though the main count missed.

What It Means For MIRM, INCY

Mirum licensed worldwide rights from Incyte in April for $16 million upfront, plus extra payments if regulatory and sales goals are met and a mid- to high-single-digit cut of future sales.

For Mirum, an approval would add another commercial product despite competition. Ipsen’s Sohonos, approved in 2023, is already on the U.S. market. Regeneron’s garetosmab (Pasatru) was granted approval in August for the same indication.

For Incyte, built on Jakafi and the skin cream Opzelura, an approval would mean a milestone payment and royalties.

How Did MIRM, INCY Retail Traders React?

On Stocktwits, retail sentiment around INCY stock remained ‘neutral’ at the time of writing and was ‘extremely bullish’ on Mirum.

While INCY stock has gained 25% year-to-date, MIRM has added 12%. 

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