The news marks a second setback for GSK's oncology portfolio this week, after the company on Monday revealed its blood cancer drug Blenrep failed to outperform an older therapy in a key study, calling into question Blenrep's existing U.S. approval. Zejula belongs to a family of drugs called PARP inhibitors - which include AstraZeneca (AZN.L) and Merck's (MRK.N) Lynparza and Clovis Oncology's (CLVS.O) Rubraca. In September, GSK withdrew the use of Zejula in certain ovarian cancer patients who had previously undergone three or more chemotherapy regimens. For GSK, Zejula's use in the first-line setting - as a therapy designed to keep cancer at bay in ovarian cancer patients who have partially or fully benefited from platinum-based chemotherapy, remains a priority. Zejula - which GSK acquired through its $5.1 billion acquisition of U.S. cancer specialist Tesaro in 2018 - generated a total of 120 million pounds ($141.4 million) last quarter.

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