Liposarcoma, a common subtype of soft tissue sarcoma, includes dedifferentiated liposarcoma (DDLPS) with high MDM2 amplification. Brigimadlin, an MDM2-p53 antagonist, showed stable disease in 75% of patients in a phase 1a/1b study. A phase 2/3 Brightline-1 trial compares brigimadlin to doxorubicin in advanced DDLPS, aiming to identify optimal dosing and assess progression-free survival.