(P 409) RETROSPECTIVE ANALYSIS OF PROGNOSTIC FACTORS INCLUDING HLA GENOTYPE IN MYXOID LIPOSARCOMA

Objective: Myxoid liposarcomas (MLPS) can express HLA-A*02-restricted cancer-testis antigens (NY-ESO-1, MAGE-A4) that are targets for adoptive T cell therapy. However, the impact of HLA status on MLPS outcomes is unknown. We conducted a retrospective analysis of MLPS patients who underwent genomic profiling with Memorial Sloan Kettering Integrated Molecular Profiling of Actionable Cancer Targets (MSK-IMPACT) to evaluate associations between clinical data and outcomes and to test the hypothesis that HLA status does not predict survival.

Methods: HLA genotype was inferred via MSK-IMPACT. Patients were considered HLA-A*02+ if they carried HLA-A*02:01, *02:05, or *02:06. Analyses were conducted separately in two cohorts: Cohort 1 (resectable disease) assessed overall survival (OS), metastatic free survival (MFS), and local recurrence free survival (LRFS); Cohort 2 (metastatic disease) assessed OS from metastasis and time to treatment failure on first-line therapy.

Results: Cohort 1 consisted of 70 patients (53% HLA-A*02+); HLA-A*02 status was not significantly associated OS, MFS, or LRFS. Increasing tumor size was associated with a shorter OS [HR =1.08, p = 0.06] and MFS [HR = 1.08, p = < 0.001]. A round cell component >=5% was associated with shorter OS, [HR = 7.1, p = 0.06] while intraabdominal primary tumor location was associated with a shorter LRFS [HR = 8.1, p = < 0.001]. Female gender correlated with a significantly longer OS [HR 0.26, p = 0.04]. Cohort 2 consisted of 54 patients (46% HLA-A*02+); HLA-A*02 status was not significantly associated with OS or time to treatment failure. Female gender again predicted significantly longer OS [HR = 0.20, p = 0.04] and a round cell component >=5% was linked to worse OS [HR = 6.0, p = 0.02].

Conclusion: HLA-A*02 status was not significantly associated with clinical outcomes in either MLPS cohort. The known high-risk features of larger tumors and round cell component were linked to worse survival, and intraabdominal primary tumors had an increased risk of local recurrence. In contrast, female gender was associated with improved survival in both cohorts. Given the small sample size, further study is needed to clarify the prognostic impact of gender and tumor location to guide individualized treatment approaches.