Real‐world use of palbociclib monotherapy in retroperitoneal liposarcomas at a large volume sarcoma center

Abstract

Palbociclib has been evaluated in early phase trials for well‐differentiated liposarcoma (WDLPS) and dedifferentiated liposarcoma (DDLPS) patients, with reported median progression‐free survival (PFS) of 18 weeks. Here, we report on real‐world use and surgical outcomes associated with palbociclib treatment. We retrospectively reviewed 61 consecutive patients with retroperitoneal WDLPS (n = 14) or DDLPS (n = 47) treated with palbociclib monotherapy between 1 March 2016 and 28 February 2021 at The University of Texas MD Anderson Cancer Center. At palbociclib initiation, median age was 64 (interquartile range [IQR] 56‐72). In WDLPS and DDLPS cohorts, the median number of prior systemic treatments was 0 (IQR 0‐0) and 2 (IQR 0‐4), respectively. Median number of prior surgeries was 2 (WDLPS IQR 1‐2.75) and 2 (DDLPS IQR 1‐3). Median PFS was 9.2 (WDLPS IQR 3.9‐21.9) and 2.6 months (DDLPS IQR 2.0‐6.1), 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). Twelve patients ultimately underwent surgical resection. Resections were macroscopically complete (R0/R1) in half (n = 6/12), among whom only one patient experienced relapse after resection (median follow‐up 7.5 months). All patients who underwent macroscopically incomplete resections progressed after surgery with median time to progression of 3.3 months (IQR 2.3‐4.4). Surgery after palbociclib treatment was not associated with improved overall survival. Efficacy of palbociclib monotherapy for patients with advanced WDLPS and DDLPS is disappointing. While palbociclib may have been used to delay surgery, there was no clear benefit from treatment and few patients achieved prolonged tumor control.

Predictive factors and a novel nomogram for recurrence of primary retroperitoneal liposarcoma: Comprehensive analysis of 128 cases

“…The therapeutic effect and application time of radiotherapy and chemotherapy on RPLS still require to be further explored. At present, surgical resection remains the method of choice for PRPLS cases with indications to obtain potential cure opportunities (5)(6)(7)14,15). In the present study, the tumor was completely resected under the condition of conforming to the standard of safe resection margin (8).…”

Marked Response to Larotrectinib in Pelvic Spindle Cell Sarcoma With Concurrent TPM3-NTRK1 Fusion and CDK4/MDM2 Amplification: A Case Report

“…The efficacy of CDK4 inhibitors such as palbociclib and abemaciclib in advanced liposarcoma with MDM2/CDK4 amplification is modest in early trials and real-world settings, 4 - 6 suggesting a cytostatic rather than cytotoxic effect. NTRK inhibitors exhibited more promising and durable responses in sarcoma harboring NTRK fusion.…”

Correlation Analysis Between Demographic, Surgical, and Pathological Characteristics with Local Recurrence‐Free Survival for Surgical Resected Retroperitoneal Liposarcoma

“…As a rare soft tissue sarcoma, RPLS has a poor prognosis and poses a serious threat to human health. At present, surgical resection is still the main treatment method for PRPLS, and is also the best way for patients with indications to obtain potential cure opportunities [5, 6, 15, 16]. Within the scope of surgical indications and on the premise of ensuring safety, in this study, we completely resected the tumor (R0 resection) as far as possible under the condition of conforming to the standard of safe resection margin [8].…”