Xuanzhu Biopharmaceutical (HKG:2575) showed positive interim phase 3 data for its CDK2/4/6 inhibitor Bireociclib, used in combination with letrozole or anastrozole for the first-line treatment of HR+/HER2- advanced breast cancer, according to a Wednesday Hong Kong bourse filing.

The results showed that the Bireociclib regimen reduced the risk of disease progression or death by 47% compared with endocrine therapy plus placebo.

The study, known as BRIGHT-3, enrolled 397 patients across 58 centers in China.

Median progression-free survival in the Bireociclib group had not yet been reached after a median follow-up of 20.7 months, compared with 18.4 to 19.6 months for the control group, the filing said.

Xuanzhu reported that the therapy demonstrated a 63.5% objective response rate, compared with 42.5% in the control arm, with most adverse events being reported as manageable and of low grade.