MapLight Therapeutics Inc. filed for an initial public offering, becoming one of few biotechnology firms to move forward with a listing in a tough year for the sector.

The Redwood City, California-based clinical-stage biopharmaceutical firm’s lead product candidate consists of two drugs for schizophrenia and Alzheimer’s disease psychosis (ADP) delivered in a fixed-dose combination, according to MapLight’s filing Friday with the US Securities and Exchange Commission.