Methylmalonic and Propionic Acidemias Treatment with HSTS5040: The HERO Study – Phase II

Methylmalonic and Propionic Acidemias Treatment with HSTS5040: The HERO Study – Phase II

Protocol Description

The goal of this multi-center investigation is to see if the drug HST5040 will help in the treatment of methylmalonic acidemia (MMA) and propionic acidemia (PA), while also studying its safety and side effects. MMA and PA are rare genetic diseases, which impair the proper digestion of fats and proteins, leading to a buildup of toxic acidic substances in the blood and altered energy metabolism.

Study Level: Phase II

Eligibility Criteria

Subject to certain exclusion criteria, this study is accepting people with MMA and PA ages 2 and older.
Males and Females: Ages 2 years and older


In this 3-part study, the drug is taken orally or via gastronomy tube twice daily. In the first part of the study, participants are monitored without treatment for 4 weeks before starting the drug therapy. Thereafter, the dosage level will be increased every 4 weeks until an optimal dose is achieved. In the second part of the study, participants will be randomly divided to either continue with their optimal dose of the study drug or take a placebo for roughly the first half of the 7-month study period. Then they will switch to the placebo or study drug, respectively, for the second half. In the final part of the study, which may extend for 5 years, participants will continue to receive their optimal dose, as determined by results from the first two parts of the study.
Visits: Up to 30, some of which may be home health visits
Duration: Up to 6 years

Status: Open to Enrollment

Source(s) of Support

HemoShear Therapeutics

Primary Investigator

Gerard Vockley, MD, PhD

Contact Information

For more information about the study or enrollment, please contact:
Lead Clinical Research Coordinator
Elizabeth McCracken, MS, CGC