Letetresgene Autoleucel in Advanced/Metastatic Myxoid/Round Cell Liposarcoma.

Purpose: The cancer/testis antigen New York esophageal squamous cell carcinoma 1 (NY-ESO-1) is a promising target in myxoid/round cell liposarcoma (MRCLS).

Methods: In this pilot study, we assessed the adoptive T-cell therapy NY-ESO-1c²⁵⁹T letetresgene autoleucel (lete-cel) in patients with human leukocyte antigen (HLA)-A*02:01-, HLA-A*02:05-, and/or HLA-A*02:06-positive advanced/metastatic NY-ESO-1-expressing MRCLS. Patients underwent a reduced-dose (cohort 1) or standard-dose (cohort 2) lymphodepletion regimen (LDR). The primary end point was investigator-assessed overall response rate (ORR). Safety was assessed through adverse event (AE) reports. Correlative biomarker analyses were performed post hoc. The trial is registered at ClinicalTrials.gov (identifier: NCT02992743).

Results: Of 23 enrolled patients, 10 in cohort 1 and 10 in cohort 2 received lete-cel. Investigator-assessed ORR was 20% (95% CI, 2.5 to 55.6) and 40% (95% CI, 12.2 to 73.8), median duration of response was 5.3 months (95% CI, 1.9 to 8.7) and 7.5 months (95% CI, 6.0 to not estimable [NE]), and median progression-free survival was 5.4 months (95% CI, 2.0 to 11.5) and 8.7 months (95% CI, 0.9 to NE) in cohorts 1 and 2, respectively. AEs included cytokine release syndrome and cytopenias, consistent with T-cell therapy/LDR. Post hoc correlative biomarkers showed T-cell expansion and persistence in both cohorts.

Conclusion: To our knowledge, this study is the first demonstrating the clinical promise of lete-cel in HLA-/NY-ESO-1-positive patients with advanced MRCLS.