PTC Therapeutics announced the initiation of the second stage of the FITE19 clinical trial to assess PTC299 in COVID-19 patients. PTC299 is an oral investigational drug with a novel dual mechanism of action that has the potential to inhibit viral replication and attenuate the uncontrolled inflammatory response that ensues after infection. PTC299 functions by targeting a cellular enzyme, dihydroorotate dehydrogenase (DHODH). By targeting this enzyme instead of a viral protein, it makes it less likely to elicit drug-resistance. Enrollment for the second stage of the trial has been initiated in multiple centers outside of the US.

"Completion of the first stage of the FITE19 trial is an important milestone that triggers the final stage of the trial to begin," said Stuart W. Peltz, Ph.D., Chief Executive Officer, PTC Therapeutics, Inc. "The lack of an effective COVID-19 treatment has significantly hampered our ability to resume our normal lives. PTC299 has a unique mechanism of action that has the potential to be an effective COVID-19 treatment for both at-home and hospitalized patients and should be effective against the wildtype virus as well as viral variants. We are working hard to bring this potential important treatment to patients as rapidly as possible."

The Phase 2/3 clinical trial is a randomized, double-blind, placebo-controlled, multicenter study designed to evaluate the efficacy and safety of PTC299 in patients hospitalized with COVID-19. The study is being completed in two stages: the first stage enrolled a smaller cohort of 40 patients followed by an interim safety analysis before enrolling the larger cohort of approximately 340 participants in the second stage. The primary endpoint of the study is to evaluate the clinical efficacy of PTC299 compared with placebo assessed by time to respiratory improvement in adult individuals hospitalized with COVID-19.

PTC299 is an investigational oral small molecule that inhibits the cellular enzyme dihydroorotate dehydrogenase (DHODH). Recently, DHODH has been independently identified as one of the top-three most promising targets for intervention in COVID-19. PTC299 is being evaluated for the potential treatment of patients with COVID-19. With a novel dual-mechanism of action, PTC299 inhibits DHODH activity which leads to a reduction of pyrimidine biosynthesis and SARS-CoV-2 viral replication, and selectively modulates the immune response by attenuating the stress-induced inflammatory cytokine storm. PTC299 has broad-spectrum antiviral activity and potent inhibition of numerous RNA viruses with low nanomolar potency. PTC299 is also currently being evaluated in an ongoing clinical study in acute myeloid leukemia (AML).