BridgeBio Pharma’s transthyretin amyloidosis medicine Attruby is off to a strong launch, while Alnylam lowered full-year sales guidance for competitor Amvuttra.
In the transthyretin amyloidosis space, BridgeBio Pharma is the clear winner coming out of second quarter earnings season. Sales of its ATTR medicine Attruby, approved in late 2024, more than tripled year-on-year, cleanly outperforming consensus expectations. Meanwhile, a key competing product, Alnylam’s Amvuttra, fell short of expectations, forcing the company to tune down its full-year guidance.
In the second quarter, Attruby brought in $222.4 million, a massive increase from the $71.5 million in sales the drug earned during the same period the year prior, BridgeBio revealed in a Tuesday earnings release. Coming into the Q2 earnings season, analysts had expected $209.2 million in Attruby revenue.
Attruby’s Q2 performance points to a “strong U.S. launch,” Jefferies said, with the analysts suggesting that the product will not slow down in the coming months. The group expects Attruby to hit blockbuster status this year, with 2026 sales projected to top $1 billion.
Analysts at William Blair agreed, telling investors in a Tuesday note that the beat is “especially notable after revenue from competitor Alnylam came in below expectations.” Last month, Alnylam reported $1.01 billion in worldwide earnings for Amvuttra, falling below the consensus of $1.05 billion. Amvuttra had a couple years’ headstart on the market, earning FDA approval in June 2022.
When reporting second quarter earnings, Alnylam lowered its full-year ATTR revenue guidance by $200 million at the midpoint—a downward adjustment that also covers the sales of the company’s other ATTR medicine Onpattro.
Alnylam’s shares crashed more than 28% in the aftermath of the announcement, wiping $10.8 billion off its market cap.
BridgeBio, meanwhile, “continues to execute on driving first-line growth by differentiating Attruby,” helping the product improve market capture, William Blair wrote on Tuesday.
Unlike Alnylam’s asset, a so-called silencer that targets transthyretin mRNA to lower the overall expression levels of the protein—including its healthy and disease-causing forms—Attruby is a transthyretin stabilizer, which works by binding to the protein to prevent misfolding, in turn avoiding the accumulation of disease-causing clumps.
Last month, the stabilizer class got a boost when AstraZeneca and Ionis Pharmaceuticals’ antisense therapy Wainua—a type of silencer that works by lowering transthyretin expression—failed the Phase 3 CARDIO-TTRansform study, unable to show significant cardiovascular benefits in patients with ATTR-cardiomyopathy.
At the time, analysts expected CARDIO-TTRansform’s disappointing outcome to be a boon for BridgeBio, with Mizuho Securities writing in a July 10 note that the Wainua fail “simplifies the ATTR-CM landscape,” removing a key competitor to Attruby.
Even among similar therapies, Attruby appears to be building a strong case for differentiation. In the stabilizer class, Attruby is going up against Pfizer’s Vyndaqel/Vyndamax, a deeply entrenched franchise that in Q2 grew 9% year-on-year to bring in $1.76 billion worldwide.
Recent readouts, however, have suggested a superior product profile for BridgeBio’s Attruby. Phase 3 data released in May pointed to potentially better all-cause mortality outcomes with Attruby versus Vyndaqel/Vyndamax, though no direct head-to-head study comparing the two drugs has been conducted. Last month, additional late-stage findings showed that Attruby could preserve kidney function in ATTR-cardiomyopathy patients, another key benefit that could set it apart from Pfizer’s products.
