US-based pharmaceutical company Pfizer has signed a research collaboration and exclusive license agreement with Clear Creek Bio, to develop an oral treatment for Covid-19.

The partnership is focused on discovering and developing potential inhibitors of the SARS-CoV-2 papain-like protease (PLpro) to treat Covid-19.

SARS-CoV-2 has two essential proteases, the main protease (Mpro) and the PLpro, which help process the viral polyprotein and support virus replication.

Under the terms of the agreement, the two companies will jointly identify a PLpro candidate to progress into the clinical trials.

Clear Creek Bio will receive an undisclosed upfront payment and will be eligible to receive additional potential milestone payments plus royalties on future product sales.

Pfizer will carry out further development and commercialisation of the candidate.

Pfizer anti-infectives chief scientific officer and head of medicine design Charlotte Allerton said: “Covid-19 has proven to be a devastating and highly unpredictable disease, one with the potential to remain a global health concern for years to come.

“It is critical that we try to stay ahead of the virus, continuing to advance clinical development opportunities for our current oral therapy as well as innovating through our internal programmes and strategic partnerships to bring forward additional monotherapy and/or combination treatment candidates that we believe may play a role in the ongoing fight against Covid-19.”

Pfizer said that the partnership will expand its anti-infective pipeline and, will complement its existing portfolio of Covid-19 products with direct-acting antiviral agents.

Clear Creek Bio is a private biotechnology company that develops therapeutics for global unmet needs, from small molecule discovery through early clinical development.

In addition to the PLpro programme, the company is also evaluating brequinar, a potent oral inhibitor of dihydroorotate dehydrogenase (DHODH), against a wide range of RNA viruses.

Clear Creek Bio chief executive officer Vikram Sheel Kumar said: “As Covid-19 continues to evolve, there is a significant need for oral antivirals with novel mechanisms of action.

“We explored the druggable SARS-CoV-2 genome and identified PLpro as a promising and untapped target. Leveraging our team’s expertise and success in bringing novel drugs from idea to approval, we internally developed highly potent PLpro inhibitors.

“We look forward to working with Pfizer, a global leader in antiviral development, to advance a new class of oral antivirals for Covid-19.”

This year, Pfizer announced acquisitions of Biohaven Pharmaceutical for $11.6bn, and Global Blood Therapeutics for $5.4bn, and has formed a new company with Roivant Sciences.