PTC Therapeutics, Inc. received authorization from the U.S. FDA to begin a Phase II/III trial to investigate PTC299, an oral, dihydroorotate dehydrogenase (DHODH) inhibitor, as a potential treatment for COVID-19. PTC299 has a novel dual-mechanism of action that has the potential to address the high viral replication and the uncontrolled inflammatory response that ensues after infection. PTC will initiate the study in the U.S. in the coming days with additional sites planned globally.

PTC299 is a small molecule tablet that inhibits the cellular enzyme DHODH which is used to produce the RNA building blocks for the production of SARS-CoV-2. PTC299 has demonstrated potent inhibition of viral replication in SARS-CoV-2 cell based assays, which has led to PTC moving rapidly into the clinic. A number of RNA viruses require the same building blocks, which explains why in preclinical tests PTC299 has shown broad-spectrum antiviral activity.

The study will evaluate the efficacy and safety of PTC299 in two stages, the first stage consisting of 40 patients, followed by a larger cohort of approximately 340 patients. The primary objective is clinical efficacy of PTC299 compared with placebo assessed by time to respiratory improvement in adult individuals hospitalized with COVID-19.

PTC299 is also being developed in oncology indications and has been studied in nine clinical trials in over 300 people, including both oncology patients and healthy volunteers.