Zevra Therapeutics Inc. will acquire Acer Therapeutics Inc. in a $91 million deal that combines two companies with expertise in rare diseases. Acer has struggled since its hot flash drug, ACER-801 (osanetant), failed to hit statistical significance in a phase IIa proof-of-concept study in March 2023. The stumble came amidst the launch of Acer’s Olpruva, a sodium phenylbutyrate for oral suspension therapy approved by the U.S. FDA in late December 2022 for treating urea cycle disorders. The day before the Zevra merger was announced, Acer reacquired the worldwide development, commercialization and economic rights to Olpruva from its development partner, Relief Therapeutics Inc.