BridgeBio Celebrates Double Success with Promising Results in Rare Diseases

BridgeBio Pharma, Inc. has reported significant breakthroughs in two rare disease treatments, sending its stock soaring and potentially reshaping the landscape for patients with autosomal dominant hypocalcemia type 1 (ADH1) and limb-girdle muscular dystrophy (LGMD).

Encaleret Exceeds Expectations in ADH1 Phase III Trial

BridgeBio's small molecule therapy, encaleret, has demonstrated remarkable efficacy in balancing calcium levels for patients with ADH1, a genetic thyroid disorder. In the Phase III CALIBRATE study involving 70 adult patients, encaleret achieved its primary endpoint with 76% of treated patients reaching target serum and urine calcium levels at week 24, compared to just 4% in the standard of care group.

The drug's performance surpassed both investor expectations and previous Phase II results, where 69% of patients achieved target levels. Mizuho analysts noted that encaleret "comfortably achieved the upside case scenario," with the therapy showing rapid efficacy – 71% of participants reached target values by day three, increasing to 98% by week 20.

Importantly, encaleret also met key secondary endpoints, with 91% of patients achieving intact parathyroid hormone (PTH) levels at week 24. The treatment was well-tolerated, with no discontinuations and 97% of participants opting to continue into a long-term extension study.

BBP-418 Shows Promise in LGMD Treatment

Earlier in the week, BridgeBio announced positive Phase II results for BBP-418, an oral small molecule aimed at treating LGMD. The drug doubled a key biomarker indicating muscle stabilization and reduced another biomarker associated with muscle damage. These results, like those of encaleret, exceeded analyst expectations.

Market Impact and Future Prospects

The successive positive trial results have had a significant impact on BridgeBio's market performance. The company's shares rose nearly 8% following the encaleret news, reaching just under $70 in pre-market trading. This increase comes on top of an 18% rise over five days, largely attributed to the BBP-418 results.

BridgeBio plans to submit an approval application for encaleret to the FDA in the first half of 2026, with analysts at Jefferies projecting potential approval in early 2027. The company is also continuing studies of encaleret in chronic hypoparathyroidism and pediatric ADH1.

Market analysts are optimistic about encaleret's potential, with Mizuho projecting peak sales of about $750 million in ADH1, while Jefferies estimates $1 billion or more. BridgeBio estimates the U.S. patient population for ADH1 at around 9,000 symptomatic individuals, with approximately 3,000 diagnosed.

These developments add to BridgeBio's growing portfolio, which includes Attruby, approved in November 2024 for transthyretin amyloid cardiomyopathy (ATTR-CM). Despite entering a competitive market, Attruby has performed well, with $71.5 million in sales in the second quarter of 2025 and expectations of continued growth.