BridgeBio Pharma, Inc. (BBIO) has secured FDA approval for Attruby (acoramidis) for the treatment of adult patients with transthyretin amyloid cardiomyopathy (ATTR-CM). This approval marks a significant advancement in the treatment of this progressive and often fatal disease, offering a new therapeutic option for patients. The FDA decision, based on the positive results from the Phase 3 ATTRibute-CM study, has led to a surge in BridgeBio's stock price.
Clinical Trial Success
The approval of Attruby was primarily based on the Phase 3 ATTRibute-CM study, which demonstrated a statistically significant reduction in all-cause mortality and cardiovascular-related hospitalizations. The study, involving 632 participants, met its primary endpoint with a Win Ratio of 1.8, indicating a substantial treatment effect. Patients treated with Attruby also experienced improvements in quality of life, as measured by the Kansas City Cardiomyopathy Questionnaire and a 6-minute walk test.
Mechanism of Action and Tolerability
Attruby is an orally administered, near-complete stabilizer of transthyretin (TTR). By stabilizing TTR, Attruby prevents the misfolding and aggregation of the protein, which leads to the formation of amyloid deposits in the heart. The drug was generally well-tolerated in clinical trials, with the most common side effects being mild and including diarrhea and abdominal pain that typically resolved without the need for drug discontinuation.
Impact on the ATTR-CM Treatment Landscape
ATTR-CM, once considered a rare disease, is now estimated to affect over 400,000 people worldwide. The condition results from the accumulation of misfolded TTR protein in the heart, leading to progressive heart failure and, without treatment, death within five years of diagnosis. Attruby is the first and only approved product with a label specifying near-complete stabilization of TTR.
Market Dynamics and Future Plans
While Attruby represents a significant advancement, it will face competition from existing therapies, such as Pfizer's Vyndaqel and Vyndamax (tafamidis). Citi analyst David Lebowitz noted that Attruby is priced at $225,000 per year, which is below the $270,000 per year for tafamidis. BridgeBio has also submitted a Marketing Authorization Application to the European Medicines Agency, with a decision expected in 2025. The company has granted exclusive rights to Bayer to commercialize acoramidis for ATTR-CM in Europe. Scotiabank analyst Greg Harrison raised the price target on BridgeBio Pharma to $48.00 from $45.00, maintaining a Sector Outperform rating.
