The US Food and Drug Administration has cleared the first China-developed cancer drug similar to Merck & Co.’s blockbuster therapy Keytruda, making it a rare success among Chinese biotechnology firms seeking to break into the world’s most lucrative market.

The FDA granted approval for Loqtorzi to Shanghai Junshi Biosciences Ltd and its US partner Coherus BioSciences Inc. to treat nasaopharyngeal cancer, the Chinese company said in a statement on Friday.

Loqtorzi belongs to a class of cancer therapies known as PD-1 inhibitors, which harness patients’ own immune systems to fight tumors. Loqtorzi was the first homegrown PD-1 therapy approved in China at the end of 2018, and it’s one of several cheaper domestic products that compete with Keytruda and Bristol-Myers Squibb Co.’s Opdivo in China.

Despite having been approved in China to treat some of the most common types of cancer, Loqtorzi’s US approval so far is limited to a rare type of tumor affecting tissue at the back of the nose and mouth. Still it’s a milestone for Chinese drugmakers, which have long faced questions over the quality of clinical trials and ability to come up with novel therapies in their push to make inroads in Western markets.

Last year, the FDA rejected cancer therapies from China’s Innovent Biologics Inc. and Hutchmed China Ltd. — which had already been approved for use in their home market — because their data didn’t sufficiently represent non-Chinese patients.

In late 2019, Beijing-based drugmaker Beigene Ltd. made history when its blood cancer medicine Brukinsa became the first China-developed oncology drug to receive FDA approval. Its PD-1 cancer drug was approved for use in the European Union in September, while its application for US approval is still being reviewed by the FDA.

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