- GlaxoSmithKline has decided against moving forward with a phase 3 outcome study of co-development partner Ionis' drug for a rare organ condition, Ionis said Thursday.
- The FDA placed a clinical hold on the drug, known as Ionis-TTR, back in April over safety concerns tied to sharp drops in patients' platelet counts.
- Ionis shares plunged on the news, falling nearly 40% compared to Wednesday's close.
Ionis said GSK would consider its options for the drug once further clinical data from ongoing studies became available.
Data from an ongoing phase 3 study in patients with TTR familial amyloid polyneuropathy is expected in the first half of 2017, while results from an investigator-initiated study in a related condition are due to be presented in July.
GSK has the option to exclusively license Ionis-TTR under its development partnership with Ionis. The phase 3 study which GSK opted out of planned to study the drug against TTR amyloid cardiomyopathy.
Both amyloid cardiomyopathy and amyloid polyneuropathy are forms of TTR amyloidosis, a progressive disease caused by the accumulation of a defective TT proteins in tissues and organs. The buildup of TTR can lead to organ failure, and eventually death.
GSK's decision certainly doesn't bold well for Ionis' valuation, especially since the transthyretin amyloidosis program comprises roughly 36% of its valuation, according to analysis from Leerink cited by The Wall Street Journal.
But Ionis' loss may be Alnylam Pharmaceuticals' win. Alnylam has a rival candidate in development and still has strong cash reserves from its $450 million IPO in January 2015. Alnylam's stock was up more than 10% on the news of GSK's decision.