Already sky high after the success of its limb-girdle muscular dystrophy therapy, reported on Monday, BridgeBio’s shares rose nearly 8% more as encaleret balanced calcium levels in patients with a genetic thyroid disorder.
Two days after BridgeBio reported the success of a limb-girdle muscular dystrophy therapy, the genetic disease biotech is back with Phase III results showing that the small molecule therapy encaleret corrected calcium levels in patients with another rare disease called autosomal dominant hypocalcemia type 1.
The main goal of the study was to reach serum and urine calcium levels within a target range. BridgeBio reported on Wednesday that 76% of patients who received encaleret reached the target at week 24 compared to 4% who received standard of care.
Analaysts at Mizuho said the results have exceeded investor and the company’s expectations, writing in a note to investors on Wednesday morning that “Encaleret comfortably achieved the upside case scenario.” The results also bested previous Phase II results that showed a 69% achievement of target serum and calcium levels—a major achievement as Phase III results are typically worse than Phase II, Mizuho noted.
Already sky high after the success of BBP-418 in limb-girdle muscular dystrophy (LGMD) reported on Monday, BridgeBio’s shares rose nearly 8% more to just under $70 apiece in pre-market trading Wednesday. The company’s stock has risen 18% in five days.
Autosomal dominant hypocalcemia type 1 (ADH1) is an inherited type of hypoparathyroidism caused by a variant in the calcium-sensing receptor (CASR) gene, leading to an imbalance in calcium in the bloodstream and urine. The condition can cause muscle cramping and spasms, seizures and kidney failure.
Patients are typically treated with calcium supplements and active vitamin D. The Phase III CALIBRATE study of 70 adult patients tested whether encaleret could increase calcium in the blood and maintain levels of endogenous parathyroid hormone (PTH), which is decreased in hypoparathyroidism. The drug did both, while also decreasing levels of calcium in the urine.
On a key secondary endpoint, 91% of patients taking encaleret achieved intact PTH at week 24.
Mizuho also noted that encaleret acted quickly, with 71% of participants achieving target values by day three after receiving the drug. That number reached 98% by week 20.
BridgeBio said that encaleret was well tolerated with no discontinuations; 97% of participants opted to continue on into a long-term extension of the study. Mizuho said the majority of treatment-emergent adverse events were mild to moderate, with most of the serious cases appearing in the standard of care arm. Analysts at Jefferies, writing in their own note Tuesday, said there were “no surprises” from the safety data.
The company plans to take the therapy to the FDA for an approval application in the first half of 2026. Jefferies believes this filing plan could suggest an approval in early 2027 and, given that BridgeBio has already held multiple meetings with the FDA, an indication covering patients 16 years and older is likely.
While that application proceeds, BridgeBio will continue studying the medicine in chronic hypoparathyroidism and pediatric ADH1.
Mizuho expects encaleret to bring in about $750 million in peak sales in ADH1, while Jefferies puts the figure higher at $1 billion or more. BridgeBio has said that the population of symptomatic patients is about 9,000 in the U.S., with about 3,000 of those diagnosed.
A Good Week For BridgeBio
The results are BridgeBio’s second Phase II win of the week. On Monday, the California biotech announced that the oral small molecule BBP-418 doubled a key biomarker in LGMD that indicates muscle stabilization. A secondary endpoint showed that the drug reduced another biomarker that indicates muscle damage. Just like with encaleret, analysts heralded the results as better than expected.
Elsewhere, BridgeBio is marketing Attruby, which was approved in November 2024 to treat transthyretin amyloid cardiomyopathy (ATTR-CM). The therapy landed in a crowded market that includes Pfizer’s Vyndaqel and Alnylam’s Amvuttra.
But the biotech’s oral offering has held its own, notching $71.5 million in sales in the second quarter thanks to 3,751 unique patient prescriptions in the U.S. Analysts are expecting to see growth when BridgeBio reports third quarter numbers on Wednesday afternoon. Jefferies predicts sales of $102 million.
Jefferies also suggests that Attruby could become “a first-line $4 billion+ pill.” BridgeBio believes the therapy is tapping into a $20 billion market opportunity, according to slides from the company’s second quarter earnings presentation.
