Factors associated with treatment response and survival outcomes in plasmablastic lymphoma: A retrospective study in a predominantly Hispanic population.

Abstract

e19099 Background: Plasmablastic lymphoma (PBL) is a rare, aggressive NHL with historically poor outcomes and a median overall survival (OS) of 9-15 months. We evaluated clinicopathologic characteristics and factors associated with response and survival in a predominantly Hispanic cohort of patients with PBL. Methods: We retrospectively analyzed 35 patients with pathologically confirmed PBL diagnosed between December 2012 and June 2025. Factors associated with response were assessed by chi-square and multivariable logistic regression. Survival outcomes were evaluated by Kaplan-Meier method with log-rank test and multivariable Cox regression. Results: Median age was 49 years; 85.7% were male, and 74.3% were Hispanic. Interim overall response rate (ORR) and complete response rate (CRR) with first-line therapy were 62.9% and 54.3%, respectively. On univariate analysis, female sex (p=.03) and LDH <220 U/L ( p <. 01) were associated with achieving CR. On multivariate analysis, LDH <220 U/L (OR .05, 95% CI .005–.54, p=.01) remained independently associated with CR after adjusting for ethnicity, age >40, ECOG >2, advanced stage, IPI ≥3, and Ki-67 >80%. With a median follow-up of 17 months, median progression-free survival (PFS) and OS were 20 and 60 months, respectively. Estimated 1-, 2-, and 5-year PFS were 59.3%, 49.2%, and 43.7%, and OS were 67.9%, 54.8%, and 46.0%, respectively. On univariate analysis, female sex (HR .29, 95% CI .09-.89, p=.03; HR .28, 95% CI .08-.96, p=.04) and achieving CR (HR .12, 95% CI .04-.34, p<.01; HR .11, 95% CI .04-.31, p<.01) were associated with improved PFS and OS. IPI ≥3 (HR 2.8, 95% CI 1.1-7.3, p=.03) and LDH ≥220 U/L (HR 2.7, 95% CI 1.0-6.9, p=.04) were associated with worse OS, but not PFS. On multivariate analysis, age >40 (HR 4.7, 95% CI 1.2-19.3, p=.03) was associated with worse PFS, but not OS. High/high-intermediate IPI scores (IPI ≥3; HR 7.4, 95% CI 1.2-47.1, p=.03; HR 12.7, 95% CI 1.4-118.6, p=.03) were independently associated with inferior PFS and OS, while achieving CR (HR .04, 95% CI .01-.38, p<.01; HR .03, 95% CI .003-.31, p<.01) was associated with improved PFS and OS, independent of LDH ≥220 U/L, interim response, disease stage, immunocompromised status, EBV status, CNS prophylaxis, radiation therapy, and autologous stem cell transplantation. Conclusions: In this predominantly Hispanic cohort, only half of patients achieved complete response following first-line therapy, with survival outcomes comparable to contemporary reports. Normal LDH at diagnosis was associated with higher CR rates, while high/high-intermediate IPI scores and failure to achieve CR after first-line therapy were associated with inferior survival. These findings underscore the need for more effective first-line treatment strategies to improve CR rates and long-term outcomes, particularly in patients with high-risk disease.