Alnylam’s now-approved Onpattro therapy opens new class of drugs

The FDA approval of Onpattro (patisiran) infusion, from Alnylam Pharmaceuticals, while expected, nevertheless is generating considerable buzz in pharmaceutical circles. The therapy is intended for a rare condition called hATTR (hereditary transthyretin-mediated amyloidosis); it addresses the polyneuropathy caused by the condition, and is the first such treatment. It is also the first FDA approval of a new class of drugs called small interfering ribonucleic acid (siRNA) treatment; more generally called RNA inhibitors, that alter the genetic drivers of a disease.

Such siRNAs work by silencing a portion of RNA involved in causing the disease, according to the FDA approval announcement. More specifically, Onpattro encases the siRNA into a lipid nanoparticle to deliver the drug directly into the liver, in an infusion treatment, to alter or halt the production of disease-causing proteins. As such, they have the potential to provide a cure, and not just addressing the symptoms of the disease.

The clinical trials that led to Onpattro approval provided the drug to patients every three weeks over an 18-month span. Relative to placebo, patients showed a meaningful improvement measured by several criteria: neuropathy impairment; a walk test; and nutritional status. According to press reports, the drug will cost $475,000 (presumably annually); it’s not clear how long patients need to be on therapy. Value-based contracting, presumably basing the reimbursement on patient outcomes, is in the works; ther are some 3,000 patients in the US currently, and over 10,000 as yet undiagnosed.

At least one of the specialty pharmacies that will be handling the drug issued its own press release: US Bioservices, a unit of AmerisourceBergen. The higher level of patient support of specialty pharmacies generally seems eminently appropriate in this case: administration of the drug requires pre-treatment with infusion of three or four other drugs to reduce the risk of “infusion related reaction,” then warming Onpattro, filtering it, and infusing. The drug is stored under refrigerated condition: 2-8°C.

US Bioservices offers home-based care as well as delivery to infusion clinics. “Patients prescribed Onpattro who receive services from US Bioservices will have access to its national team of in-home nurses …” says a company statement. “The company’s telephonic nurses will be available to provide 24/7 clinical support to patients on therapy. In-home and telephonic nurses work in a clinically-coordinated way with the prescribing physician and other members of the patient’s care team to improve access, adherence and outcomes,” says a company statement.