RHB-107 (INN: upamostat), an investigational drug, is a first-in-class, once-daily, orally administered inhibitor of serine proteases targeting multiple potential indications, including viral infections such as COVID-19 and influenza, oncology and inflammatory gastrointestinal diseases.
Viral Infections:
RHB-107 is a potentially broad-acting, host-directed antiviral that targets host cell factors involved in preparing the spike protein for viral entry into target cells and has the potential to remain effective against emerging viral variants with spike protein mutations.
RHB-107 successfully completed a Phase 2 study in non-hospitalized symptomatic COVID-19 patients, which evaluated the safety and tolerability profile of RHB-107, along with efficacy signals. The study’s positive results were published in the peer-reviewed International Journal of Infectious Diseases.
RHB-107 was included in the U.S. Government-supported PROTECT study, which was a Phase 2 adaptive, randomized, double-blind, placebo-controlled platform trial to evaluate the safety and efficacy of RHB-107 for early outpatient COVID-19 treatment. The study was conducted as part of a master protocol evaluating promising investigational products for safety and efficacy as early outpatient treatment and post-exposure prophylaxis for COVID-19. RHB-107 was the first and only drug to enter the platform and was evaluated in the early treatment arm of the study. The study was planned for a duration of approximately 18 months, but due to challenges to enrollment and U.S. Government funding limitations, enrollment was discontinued after a total of only 92 of the planned 300 participants were enrolled. While a benefit in time to resolution of symptoms and time to viral clearance were observed regarding the efficacy of RHB-107 in this study it did not reach statistical significance. Whether the lack of significant results were due to true lack of efficacy or accrual of fewer than one third of the planned number of patients is unknown.
Preclinical evaluation of RHB-107 in influenza is planned.
RHB-107 completed several Phase 1 studies and two Phase 2 proof-of-concept studies in cancer patients. The first Phase 2 study was in locally advanced, non-metastatic pancreatic cancer and the second study was in metastatic breast cancer in combination with first-line chemotherapeutic agents.
RHB-107 was granted FDA Orphan Drug Designation for the adjuvant treatment of pancreatic cancer.
The clinical studies with RHB-107 are registered on www.ClinicalTrials.gov, a web-based service by the U.S. National Institute of Health, which provides public access to information on publicly and privately supported clinical studies.