FCN-437c + letrozole

FCN-437c + letrozole is an investigational combination therapy being studied primarily for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced or metastatic breast cancer. FCN-437c is a novel, orally available small molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), developed to block cell cycle progression by inhibiting phosphorylation of the retinoblastoma protein and thereby arresting tumor cell growth. Letrozole is a well-established aromatase inhibitor that reduces estrogen production, further suppressing hormone-driven tumor proliferation. The combination aims to enhance antitumor activity in HR+/HER2– breast cancer patients who are postmenopausal or have advanced disease[1][7][8]. Clinical studies have shown that this regimen is generally well tolerated and demonstrates promising antitumor activity in this patient population[1][7].