Findings demonstrated disappointing efficacy of palbociclib monotherapy for patients with advanced well-differentiated liposarcoma (WDLPS) and dedifferentiated liposarcoma (DDLPS). While palbociclib could have been administered to delay surgery, there was no obvious advantage from treatment and prolonged tumor control was achieved in few cases.

• In early phase trials, palbociclib has been assessed for WDLPS and DDLPS, with documented median progression-free survival (PFS) of 18 weeks.

• A retrospective review of 61 consecutive patients with retroperitoneal WDLPS (n = 14) or DDLPS (n = 47) treated with palbociclib monotherapy was performed to determine real-world use and surgical outcomes associated with palbociclib treatment.

• A median PFS of 9.2 (WDLPS IQR 3.9-21.9) and 2.6 months (DDLPS IQR 2.0-6.1) was achieved, with median time on treatment of 7.4 months (WDLPS IQR 3.5-14.2) and 2.7 months (DDLPS IQR 2.0-5.7).

• Surgical resection was required in 12 cases.

• Resections were macroscopically complete (R0/R1) in half (n = 6/12), among whom only one patient had relapse post-resection (median follow-up 7.5 months).

• Progression post-surgery was evident in all patients who had macroscopically incomplete resections, and the median time to progression was 3.3 months (IQR 2.3-4.4).

• Surgery after palbociclib use was not linked with improved overall survival.