Candidate: EDP-235


Type: Oral protease inhibitor specifically designed to target conserved regions in the active site of a viral enzyme essential for SARS-CoV-2 replication. As a result, Enanta said, it does not expect mutations in the spike protein to affect the activity of EDP-235.

2021 Status: Poster Presentation–Enanta said Octoober 6 that it plans to present new preclinical data for EDP-235 through a poster at the International Society for Influenza and Other Respiratory Virus Diseases (ISIRV)-World Health Organization Virtual Conference (WHO): COVID-19, Influenza and RSV: Surveillance-Informed Prevention and Treatment. The conference is being held virtually October 19-21, 2021.

CLINICAL CANDIDATE IDENTIFIED–On August 5, Enanta said it identified EDP-235 as its lead oral protease inhibitor specifically designed for the treatment of COVID-19. The company said it plans to advance EDP-235 into the clinic early next year, through a Phase I single and multiple ascending dose study designed to evaluate the safety, tolerability, and pharmacokinetics of EDP-235 in approximately 75 healthy volunteers.

According to Enanta, EDP-235 potently and selectively inhibited SARS-CoV-2 replication in multiple cellular models, including primary human airway epithelial cells, with an EC90 of 33nM. EDP-235 also demonstrated activity against other coronaviruses, providing the opportunity to potentially treat other infections that may emerge in the future.

EDP-235 also retained activity against protease enzymes from currently circulating SARS-CoV-2 variants; showed a clean preclinical safety profile; showed a high barrier to resistance; and showed “excellent” lung distribution in rats, demonstrating properties supportive of once daily oral dosing, Enanta said.

2020 Status: Enanta on March 13 said it had begun a program to discover direct-acting antiviral drug candidates to treat COVID-19, using a two-pronged approach: Testing compounds from its antiviral compound library for potential activity against the virus, and discovering new candidates by using its expertise in direct-acting antiviral mechanisms. Four days later, Baird Equity Research cited that strategy, and the company’s antiviral experience, in upgrading Enanta to “Outperform”: “In our view, Enanta’s core competencies are a perfect fit for tackling the COVID-19 pandemic, head on.”

Enanta also said it will launch a Phase II dose ranging study in pediatric respiratory syncytial virus (RSV) patients and a Phase II study in adult transplant patients with RSV, in addition to its ongoing Phase IIb RSVP study in adult outpatients with community-acquired RSV, noting that patients at higher risk for RSV such as older adults and people with weakened immune systems show a similar patient profile as patients with COVID-19.

COVID-19: 300 Candidates and Counting

To navigate through the >300 potential therapeutic and vaccine options for COVID-19, GEN has grouped the candidates into four broad categories based on their developmental and (where applicable) clinical progress:

FRONT RUNNER – the most promising therapeutics/vaccines based on clinical progress, favorable data or both.

DEFINITELY MAYBE – earlier phases with promising partners, or more advanced candidates in development that have generated uneven data

KEEPING AN EYE ON… – interesting technology, attracting notable partners, or both, but preliminary data.

TOO SOON TO TELL – longshots pending additional experimental and/or clinical data.

GEN has also tagged the most common treatment types:


Previous articleEnzo Biochem
Next articleSecarna Pharmaceuticals