Dedifferentiated Liposarcomas Treated with Immune Checkpoint Blockade: The MD Anderson Experience

Madeline B Torres^1,2Cheuk Hong Leung³Marianne Zoghbi⁴Rossana Lazcano⁵Davis Ingram⁵Khalida Wani⁵Emily Keung¹M Alejandra Zarzour⁴Christopher P Scally¹Kelly K Hunt¹Anthony Paul Conley⁴Andrew J Bishop⁶B. Ashleigh Guadagnolo⁶Ahsan Farooqi⁶Devarati Mitra⁶Alison K Yoder⁶Michael Nakazawa⁴Dejka Araujo⁴J Andrew Livingston⁴Ravin Ratan⁴Shreyaskumar Patel⁴Vinod Ravi⁴Alexander J Lazar^5,7Christina Roland¹Neeta Somaiah⁴Elise F. Nassif Haddad^4,8*

• ¹Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, United States
• ²Department of Surgery, Cooper University Hospital, Cooper Medical School of Rowan University, Camden, United States
• ³Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, United States
• ⁴Department of Sarcoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, United States
• ⁵Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States
• ⁶Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Ohio, United States
• ⁷Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, United States
• ⁸Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, United States

Background: Dedifferentiated liposarcoma (DDLPS) is one of the most common types of soft tissue sarcoma (STS) characterized by liposarcomatous differentiation and a predilection for the retroperitoneum. Despite the growing number of histology-specific immune checkpoint blockade (ICB) trials in STS, it is still difficult to identify the radiographic objective response rate (ORR) for DDLPS in the real world setting. This study aimed to evaluate the ORR and survival of patients with DDLPS treated with ICB at a single center. Methods: We conducted a retrospective study of 31 patients with pathologically confirmed DDLPS treated with ICB at MD Anderson Cancer Center between 2018 and 2023. Patient demographics, disease characteristics, treatment history, and response to ICB were analyzed. Immunohistochemical analysis was performed on tumor samples to assess immune-related markers. Results: ORR by RECIST 1.1 was 3.2% (n=1/31). Among all patients (n=31), 6% achieved partial radiographic response, while 39% had stable disease, and 55% showed progressive disease. Median progression-free survival (PFS) was 3.5 (95%CI:1.9, 4.7) months, and overall survival (OS) after ICB initiation was 19.7 (95%CI: 8.8, not reached) months. Patients without prior systemic therapy demonstrated better OS (p=0.004). Immunohistochemistry revealed no relationship between pre- or post-ICB expression of CD8, CD20, CD21 and PDL-1 and response. Conclusion: While the response to ICB in DDLPS remains limited, specific immune markers may influence treatment outcomes. CD20/21 post-ICB appear more important for prognosis. Further research is warranted to identify predictive factors for ICB efficacy in DDLPS.