Survival outcomes of plasmablastic lymphoma according to immune status.

7088 Background: Plasmablastic lymphoma (PBL) is a rare, aggressive subtype of NHL associated with HIV, but also reported in other immunosuppressed states. Outcomes of PBL patients with non–HIV-related immunosuppression remain poorly defined. We compared clinicopathological features and survival outcomes among patients with HIV-associated immunosuppression (IS-HIV), and non–HIV-related immunosuppression (IS) and those without HIV or history of immunosuppression (IC). Methods: We retrospectively analyzed 35 patients with pathologically confirmed PBL, including 14 IC, 16 IS-HIV, and 5 IS patients. Associations between immune status and clinical characteristics were assessed using chi-square analysis. Progression-free survival (PFS) and overall survival (OS) were evaluated using Kaplan–Meier analysis with log-rank testing and multivariable Cox proportional hazards regression. Results: Median ages were 49, 45, and 56 years for IC, IS-HIV, and IS groups, with male predominance across all groups (71.4%, 93.8%, and 100%), respectively. Epstein–Barr virus positivity was significantly higher in IS-HIV (93.8%) and IS (40.0%) compared with IC patients (14.3%; p < 0.01). IS patients had lower rates of extranodal involvement than IC and IS-HIV patients (80.0% vs 100%; p = 0.04). Immune status was not associated with age, sex, ethnicity, ECOG performance status, stage, IPI score, radiation therapy, CNS prophylaxis, or autologous stem cell transplantation. Rates of primary refractory disease and relapse did not differ significantly among IC (14.3%, 21.4%), IS-HIV (31.3%, 12.5%), and IS (40.0%, 0%) groups (p = .42 and p = .48, respectively). Response rates following first-line therapy were numerically lower in IS patients but did not differ significantly ( p = 0.23). Median follow-up was 30, 21, and 4 months for IC, IS-HIV, and IS groups, respectively. Median PFS was 60.5 months, not reached, and 4 months for IC, IS-HIV, and IS groups, respectively ( p = 0.03). One- and two-year OS rates were 78.6% and 64.3% (IC), 74.0% and 65.8% (IS-HIV), and 0% and 0% (IS; p = 0.02). On multivariable analysis, IS status was associated with inferior PFS (HR 3.6, p = 0.03) and OS (HR 3.9, p = 0.03), whereas IS-HIV was not. Conclusions: PBL patients with non–HIV-related immunosuppression experienced significantly inferior PFS and OS compared with IC and IS-HIV patients. Although lower response rates and higher primary refractory disease were observed in IS patients, these differences did not reach statistical significance, likely due to small sample size. Consistent with prior reports, HIV-associated immunosuppression was not associated with worse survival. Larger studies are needed to better define disease biology and optimize therapeutic strategies for this high-risk population.