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Oct. 6. Patisiran is currently under review in Europe. The main differences between the two drugs are the dosing method and their safety track record.
Transthyretin normally helps ferry vitamin A and thyroid hormone around the body. The flurry of activity to treat the misfolded version falls into two camps. Alnylam and Akcea have drugs that cut off the protein’s production. They are called gene silencers. The Pfizer and Eidos experimental drugs prevent transthyretin from misfolding and causing damage. They are called stabilizers. The generic anti-inflammatory diflunisal is also used as a stabilizer.
Pfizer’s lack of detailed data for tamafidis in hereditary ATTR seemed to boost Alnylam shares, which were up more than 16 percent to $112.57 in late trading Monday. Akcea shares were up a more modest 1.5 percent to $33.12. With a stabilizer drug like tamafidis that’s yet to clear Phase 2, Eidos shares were punished today by investors, dropping more than 30 percent to $14.10.
It makes sense to combine the two types of drug if enough options are eventually available, but much will depend on price. “If you’re Pfizer and don’t have a lot of business savvy and you price at $200,000 a year for a 20 mg pill, [a patient] cannot combine an expensive silencer with a stabilizer,” said Berk.
The “expensive silencer” he’s referring to is patisiran. Alnylam has set an annual cost of $450,000 but estimates that discounts will knock an average of $100,000 off the price per patient. Alnylam officials also promised to give money back if patisiran doesn’t perform as advertised.
[The original story said Pfizer omitted certain details from the study. A Pfizer representative says Pfizer never intended to release the details at this time, therefore it is not an omission. The headline and text have been adjusted.]
Image of amyloidosis by Yale Rosen via Creative Commons 2.0.