What happened

Shares of BridgeBio Pharma (BBIO 0.08%) were skyrocketing 61.2% higher as of 11:55 a.m. ET on Monday. The huge gain came after the company announced positive results from a patient cohort in a phase 2 clinical study evaluating infigratinib in treating children with achondroplasia, a genetic disorder that's the most common cause of short stature.

BridgeBio reported that the highest dose level (0.25 mg/kg once daily) of infigratinib achieved a statistically significant improvement in the mean change in baseline annualized height velocity (AHV). The company said that 80% of children at six months saw their AHV increase by at least 25%. The safety profile for infigratinib also looked good, with no adverse events evaluated as related to the treatment in the patient cohort for which results were announced today.

So what

The spectacular gain for the biotech stock underscored just how good BridgeBio's clinical results were. Infigratinib could set the bar in terms of efficacy in treating achondroplasia. The disease affects around 55,000 people in the U.S. and Europe, including as many as 10,000 young children and adolescents.

Now what

BridgeBio has already begun to enroll children in a pivotal phase 3 clinical trial of infigratinib in treating achondroplasia. The drugmaker also plans to move forward with clinical studies evaluating the experimental therapy in treating hypochondroplasia, a condition that's closely related to achondroplasia. BridgeBio founder and CEO Neil Kumar stated that his company will explore the potential for the experimental drug in treating other skeletal dysplasias as well.