BridgeBio Pharma Inc's experimental drug for a rare heart disease showed significant improvement in patients in a late-stage study, sending its shares up 60% in premarket trading on Monday.

The drug was 1.8 times better than placebo when measured for preventing death, hospitalization and improvement in 6 minutes walking distance as part of the main goal, the company said.

The drug, acoramidis, also helped improve survival by 81% in patients on the treatment compared to 74% on the placebo, and also reduced frequency of heart disease-related hospitalization by 50%.

No safety concerns were identified, the company said.

BridgeBio plans to submit the data to the U.S. Food and Drug Administration (FDA) by the end of 2023 as part of its marketing application. The company also expects to file in additional markets next year.

Acoramidis is being developed to treat transthyretin amyloid cardiomyopathy, which is characterized by the buildup of abnormal deposits of protein called amyloid that can lead to heart failure.

Alnylam Pharmaceuticals Inc is also seeking approval for its drug, patisiran, for the same condition and the FDA is set to decide by Oct. 8.

Alnylam's drug is already approved to treat polyneuropathy, another symptom of the disease, which causes malfunction of nerves that results in tingling, numbness and kidney dysfunction.

Other drugs that treat symptoms of the disease include Pfizer's tafamidis sold under the brand names, Vyndaqel and Vyndamax, for polyneuropathy and cardiomyopathy, respectively. Ionis Pharmaceuticals' injection, Tegsedi, targets polyneuropathy.

BridgeBio's shares were trading at $28.80 before the bell.