- Sales of Alnylam Pharmaceuticals' rare disease drug Onpattro more than doubled between the fourth quarter of last year and the first three months of 2019, outstripping expectations and helping to ease worries of a slow start for the therapy.
- By the end of the first quarter, more than 400 patients were on commercial treatment with Onpattro, which last year became the first RNA interference therapeutic to win U.S. approval. That figure was double what Alnylam reported at the end of 2018.
- Onpattro remains in the early phases of its launch, however, and investors appeared cautious on how well Alnylam can identify new patients with hereditary ATTR amyloidosis, the disease Onpattro treats. A new competitor looms as well: Pfizer expects to win Food and Drug Administration approval this July for tafamidis, a potential rival.
As first-to-market with a new type of drug, Alnylam has had to build a market for Onpattro (patisiran).
While Onpattro has been commercially available for less than a year, first quarter results suggest Alnylam has had some success at accomplishing that task.
"We're ... very pleased with the overall and continued global demand this quarter even with competition from recent market entrants and the availability of investigational drugs through a very large expanded access program and clinical trials," said Alnylam president Barry Greene, speaking on the company's first quarter conference call.
Greene's referring to Ionis Pharmaceuticals and Akcea Therapeutics' Tegsedi (inotersen), which launched with a similar indication several months after Onpattro, and tafamidis, an experimental drug from Pfizer that treats a related phenotype of ATTR amyloidosis.
Tafamidis could win approval by July, potentially making the amyloidosis market more competitive.
Alnylam's results from the first three months of 2019 help to build confidence the biotech can maintain its lead.
Sales of Onpattro totaled $26.3 million, up from $12.1 million in the fourth quarter. While start forms submitted to the company through its Alnylam Assist program fell, the company highlighted that prescriptions outside that program now account for 20% to 25% of demand for the drug — a sign of increasing physician comfort, Alnylam said.
Alnylam also noted signs that some doctors are switching patients to Onpattro from other products, including tafamidis.
"A number of patients in Europe, specifically France and Germany, are patients that a physician has deemed progressing on tafamidis and need to add or switch to Onpattro," Greene said. Tafamidis has been approved in Europe for familial amyloid polyneuropathy, a related indication.
Yet while first quarter numbers beat Wall Street expectations, Alnylam still has its work cut out for it. Initial sales were boosted by a bolus of patients coming onto commercial drug from the clinical development program.
To sustain growth, Alnylam will need to continue identifying new patients. To do that, the biotech has set up a genetic screening program called Alnylam Act. More than 13,000 patient samples have been submitted so far, yielding 850 positive tests for the pathogenic TTR mutation.