As Alnylam’s Amvuttra sales disappointed, revenue from BridgeBio’s rival transthyretin amyloidosis (ATTR) drug Attruby came in above analysts’ expectations.
With Attruby’s $222 million in second-quarter U.S. sales beating Wall Street consensus by 6%, Jefferies analysts expect the ATTR stabilizer could surpass the $1 billion mark in annual global sales this year. In Europe, where the drug is sold by Bayer under the brand name Beyonttra, the German pharma didn’t break down its specific sales number in its recent quarterly report.
BridgeBio’s earnings report comes a few days after Alnylam’s $1.01 billion quarterly haul from its silencer drug Amvuttra undershot analysts’ projections by 4% despite its 106% year-over-year growth.
Despite their divergent second-quarter performance against consensus estimates, the two companies are now targeting the same population—first-line ATTR-cardiomyopathy patients—as the silencer-vs-stabilizer debate drags on.
As AstraZeneca and Ionis’ fellow silencer Wainua failed the phase 3 CARDIO-TTRansform trial in ATTR-CM, BridgeBio sees the market shaping up to be “a stabilizer-first market,” CEO Neil Kumar, Ph.D., said on the company’s earnings call Monday.
The overall ATTR-CM market grew 19% in the second quarter, “substantially outstripping the market growth observed in the last three quarters,” Kumar observed.
“Consistent with these numbers is the growth in frontline patients, where stabilizers have dominated share, a trend that we think will strengthen as we learn more from CARDIO-TTRansform’s important results,” he added.
In CARDIO-TTransform, 57% of patients in each arm received a stabilizer treatment at baseline, and another 24% started a stabilizer midway into the trial, according to Ionis. These data suggest stabilizers are indeed the go-to first-line choice, and the trial’s failure suggests that combining a silencer with a stabilizer “offers no meaningful additive benefit,” Jefferies analysts wrote in an Aug. 10 note.
For its part, Alnylam has pointed to its Helios-B trial, in which Amvuttra showed a roughly 41% reduction in the risk of all-cause mortality up to 42 months among patients who were already on a stabilizer at baseline, although that subgroup analysis was not statistically powered.
Both BridgeBio and Alnylam have noted some weaknesses in second-line uptake, as they touted launch progress in the first-line setting.
For Attruby, Kumar suggested a front-line share gain of 2 to 3 percentage points, although he acknowledged that inventory dynamics from Pfizer’s first-to-market stabilizer, Vyndamax, made it difficult to calculate the exact numbers.
As for Amvuttra, Alnylam’s chief commercial officer Tolga Tanguler highlighted during a recent call that the siRNA therapy represents more than 50% of new patient starts among physicians who have prescribed it before, suggesting that doctors prefer Amvuttra once they’ve developed experience.
BridgeBio has been targeting about 30% to 40% of the overall ATTR-CM market share. But that was before Wainua’s surprise fail. Now, the California biotech plans to update its peak share guidance after analyzing detailed CARDIO-TTRansform results slated to be presented at the European Society of Cardiology Congress 2026 in Munich at the end of August.
The company’s current market share goal equates to more than $4 billion in peak sales.