Shares of Prelude Therapeutics gained after the company recorded a narrower loss in the second quarter and shared plans to start a trial for a potential breast cancer treatment.

The stock rose 13% to $6.55 on Thursday. Shares have more than doubled year to date.

The clinical-stage oncology company posted a second-quarter loss of $13.9 million, or 14 cents a share, compared with a loss of $31.2 million, or 41 cents a share, a year earlier. Analysts polled by FactSet expected a loss of 20 cents a share.

Revenue was $5.7 million, compared with $0 a year ago.

Prelude said it has made progress on its three core programs, and expects to initiate the first clinical trial of PRT13722 in hormone receptor-positive breast cancer in the fourth quarter. The start of the Phase 1 study is pending clearance of the company's investigational new drug application.