Ra Pharma puts its best foot forward with PhII Soliris rival, but shares crash after comparison to Alexion’s next-gen drug

Early this morning, investigators for Cambridge, MA-based Ra Pharmaceuticals $RARX put their best foot forward when they rolled out interim Phase II data for their rival to Soliris, Alexion’s $ALXN powerfully pricey therapy for paroxysmal nocturnal hemoglobinuria, or PNH.

Douglas Treco, Ra Pharma CEO

The data looked good for the patients who were Soliris-naive, with 8 of 10 staying on therapy. In a tiny group of 5 patients in the transfusion-independent group who switched from Soliris to RA101495, LDH levels were stable with no episodes of breakthrough hemolysis. Seven of the 11 hard-to-treat Soliris patients did experience hemolysis, though, when they converted to the experimental drug and switched back.

For a drug that is self-injected at home versus infused very two weeks at a center, Jefferies thought the Phase II data cut looked fine; approvable and reimbursable.

Investors, though, were anything but pleased by the numbers, and the stock cratered badly, plunging 37% in a rout.

So what went wrong?

Geoffrey Porges at Leerink, taking the bear perspective, says it looks like Alexion is about to whip Ra at beating out Soliris. The new team at Alexion have put considerable emphasis behind their next-gen program for ALXN1210, which Porges says can be approved in H1 2019 or before.

Geoffrey Porges, Leerink

Overall Ra’s data looked mixed, said Porges, leaving Alexion in the driver’s seat for wrapping better results earlier than Ra — which is looking at a Phase III start in the second half of next year. Notes Porges:

ALXN1210 is moving the bar of lactate dehydrogenase (LDH), a biomarker of hemolysis activity, from 1.5x the upper limit of normal (ULN), to 1x ULN, which RA101495 does not appear likely to match. Instead, Ra are producing equivalent data to Soliris in treatment-naïve PNH patients. The drug is also only addressing the small population of inadequately controlled patients that have intolerance to Soliris, but may actually be inferior in patients for whom Soliris does not fully work.

And those daily subcutaneous injections, he says, won’t look so good to patients happy to get an infusion every 8 weeks.

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Recursion Pharmaceuticals Salt Lake City, UT
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Atlas Venture Cambridge, MA

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