SY-5609 + fulvestrant

SY-5609 + fulvestrant is an investigational combination therapy for advanced solid tumors, particularly hormone receptor-positive (HR+), HER2-negative breast cancer. SY-5609 is a highly selective, potent, oral small molecule inhibitor of cyclin-dependent kinase 7 (CDK7), a key regulator of cell cycle progression and transcription. Fulvestrant is a selective estrogen receptor degrader (SERD) that antagonizes and degrades the estrogen receptor. The combination aims to target both cell cycle control/transcription_al regulation via CDK7 inhibition and hormonal signaling via estrogen receptor degradation. Early-phase clinical trials have shown acceptable safety profiles and preliminary evidence of anti-tumor activity in heavily pretreated patients with advanced HR+, HER2-negative breast cancer[1][2][8].