AstraZeneca PLC's application to release cancer drug Imfinzi in China was accepted by regulators Dec. 26, according to the country's Center for Drug Evaluation.

Imfinzi, also known as durvalumab, is an immuno-oncology checkpoint inhibitor that works by blocking the PD-L1 arm on tumor cells from linking up with a partner arm called PD-1 on the surface of immune cells, allowing the immune system to target the tumor.

The drug first received approval from the U.S. Food and Drug Administration in May 2017 as a treatment for patients diagnosed with bladder cancer. In February 2018, the U.S. regulator gave the nod to the drug for treating non-small cell lung cancer that has not spread to other organs but cannot be removed through surgery, followed by approval from the European Medicines Agency for the same in September.

China's National Medical Products Agency, which controls the Center for Drug Evaluation, gave green lights to four PD-1 drugs in 2018 — Bristol-Myers Squibb Co.'s Opdivo, Merck & Co. Inc.'s Keytruda, Shanghai Junshi Biosciences Co. Ltd.'s toripalimab and Innovent Biologics Inc.'s sintilimab.

AstraZeneca has an 8% market share in the Chinese oncology market from drugs like Tagrisso, Iressa and others, according to a presentation by the company in December.