A Pfizer cancer drug partner in China is considering a sale as the biotech’s commercial path in the U.S. looks uncertain and competition in its home country intensifies.

CStone Pharmaceuticals is exploring strategic options including a sale, Bloomberg reports, citing people familiar with the company.

The news comes just one month after the company’s Pfizer-partnered PD-L1 inhibitor Cejemly (sugemalimab) got an expanded approval in China for unresectable stage 3 non-small cell lung cancer (NSCLC) that hasn’t progressed following chemoradiotherapy. The drug earned its initial go-ahead late December for use alongside chemotherapy in newly diagnosed metastatic NSCLC.

Pfizer had signed on to help develop and lead marketing of Cejemly in China back in 2020. The deal saw the drugmaker make a $200 million equity investment to take a 9.9% stake in CStone. The pair also set up a strategic partnership to bring additional oncology assets to the Chinese market.

Shortly after that China agreement, CStone transferred ex-China rights to Cejemly and its PD-1 inhibitor nofazinlimab, or CS1003, to U.S. firm EQRx.

Besides those PD-1/L1 deals, CStone also serves as Blueprint Medicines’ partner in China for RET inhibitor Gavreto and KIT inhibitor Ayvakit as well as the Chinese seller of Servier’s IDH inhibitor Tibsovo.