At ASCO 2026, a phase 3 trial shows abemaciclib significantly delays progression in advanced dedifferentiated liposarcoma (DDLS), extending median progression-free survival to 9.7 months versus 1.5 months with placebo.

Across nine U.S. centers, the randomized, double-blind study found abemaciclib halted tumor growth for about 10 months, roughly six times longer than placebo, with roughly one-third of patients achieving responses lasting longer than the average.

Funding for the research includes the National Cancer Institute, Cycle for Survival, and philanthropic resources, underscoring government and charity support in rare-disease work.

DDLS most often affects people in their early 60s and typically arises in the retroperitoneum; surgery remains the main treatment, while chemotherapy offers limited or short-lived benefits.

The work builds on decades of CDK4/6 biology linking to DDLS growth, with foundational studies from MSK guiding the current trial.

CDK4 amplification is a defining feature of DDLS, and abemaciclib was chosen for its selective CDK4 inhibition and favorable continuous-dosing profile.

Early signals point to a subset of patients deriving long-term benefit (stable disease or partial responses lasting years), with biomarker work pursuing predictors and resistance mechanisms like cyclin D amplification.

Trial participant Andi Straus described dramatic quality-of-life and functional improvements after dose adjustments, illustrating real-world impact of the therapy.

The study enrolled patients from 2021 to 2024 via the SARC cooperative group, highlighting the infrastructure needed for rare-disease trials.

Toxicities mirror breast cancer data for CDK4/6 inhibitors, with myelosuppression and diarrhea; about 39% required dose reductions, suggesting some patients may benefit from lower starting doses.

DDLS has few effective treatments beyond surgery, making this trial a potentially significant advancement for the disease.

Phase 2 data with palbociclib, followed by abemaciclib, established the groundwork, with abemaciclib offering better CDK4 selectivity and contributing to the Phase 3 success.