(Yicai) Jan. 24 -- US pharma giant Pfizer’s new antiviral therapy for the respiratory syncytial virus, which is a common infection of the respiratory tract, has been given the nod to start clinical trials in China this week, following the granting of a similar permission to UK rival GSK last year.

Pfizer has launched an international multi-center Phase II/III clinical study of sisunatovir, an oral fusion inhibitor, that includes China, according to latest information posted on the China Drug Clinical Trial Registration and Information Publicity Platform on Jan. 22.

Cao Bin from the China-Japan Friendship Hospital is the principal investigator in the study, which plans to enroll 408 researchers in China and 2,715 internationally.

There are no antiviral drugs for the illness currently available, Wang Xinyu, deputy director of the Department of Infectious Diseases at Fudan University's Huashan Hospital, told Yicai. Existing treatments are mainly aimed at relieving symptoms, he added.

New York-based Pfizer acquired the rights to sisunatovir, which was granted Fast Track designation by the US’ Food and Drugs Administration in 2020, when it acquired US biopharma firm ReViral in 2022 for around USD525 million.

A number of multinationals, including London-based GSK, Sanofi, AstraZeneca and Moderna are developing RSV vaccines and treatments, and the market is expected to reach nearly USD5 billion by 2030.

Last year, Pfizer and GSK’s RSV vaccines were approved by the FDA but the two jabs have not yet been granted permission to go to market in China.

Moderna is also developing a RSV vaccine, based on the mRNA platform, that is expected to be given the greenlight from the FDA this year. The Cambridge, Massachusetts-based company said last year that it is building a factory in China and that its respiratory jabs, including RSV, should be the first to be launched in China.

Editor: Kim Taylor