Flex Pharma Inc. said Wednesday it will lay off more than half its employees, as it ends its phase 2 clinical trial of FLX-787 in amyotrophic lateral sclerosis and Charcot-Marie-Tooth due to oral tolerability concerns. The biopharmaceutical company’s stock was halted for news until 7:30 a.m. ET. The company said trial data shows that FLX-787 has clear potential to reduce cramps and spasms in patients with multiple sclerosis and ALS. “However, recent observations of oral intolerability at the current dose and formulation, in a subset of patients, in both studies, indicate that more formulation and dose-ranging studies are required, which is challenging for the Company based upon our current resources,” said Chief Executive Bill McVicar. The company said it has decided its best path forward is to assess strategic alternatives, including the potential sale of the company. Flex Pharma said it will reduce its workforce by about 60% as part of a restructuring to cut costs. The stock had climbed 20% year to date through Tuesday, while the iShares Nasdaq Biotechnology ETF had gained 3.9% and the S&P 500 had advanced 4.2%.