Patient Characteristics and Outcomes in Plasmablastic Neoplasms: An Institutional Retrospective Study

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.6272-6272
• Main Authors: Kolawa, Adam, McLain, Julian Hardy, Siddiqi, Imran, Mohrbacher, Ann
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-185129

Introduction: Plasmablastic myeloma (PBM) and plasmablastic lymphoma (PBL) are rare hematologic neoplasms that are pathologically difficult to distinguish. PBM represents less than 5% of all myelomas and is characterized by neoplastic proliferation of atypical plasmablasts in the bone marrow and extramedullary sites. Immunophenotypically, the neoplastic cells lack CD45 expression and exhibit plasma cell markers (CD38, CD138), with MYC overexpression and high proliferative index. PBLs are commonly seen in immunocompromised patients and account for ~2% of all HIV-related lymphomas. Histologically, they resemble diffuse large B cell lymphoma (DLBCL), but have a distinctly immunoblastic or plasmablastic morphology. Similar to PBMs, the neoplastic cells of PBLs are positive for plasma cell markers but negative for conventional B-cell markers (CD20, PAX5). Clinically, plasmablastic neoplasms respond poorly to therapy and have an aggressive clinical course, with median overall survival in some studies ranging from 8 to 15 months. There is no established standard of care for these disorders, and further characterization of this complex patient population is needed. Methods: Patients were identified from the pathology database at Los Angeles General Medical Center and Norris Comprehensive Cancer Center. Patient demographics, treatment, and clinical outcomes were collected for each patient. Overall survival was calculated for the total cohort, as well as patient subgroups including disease type, and HIV status. Results: We retrospectively identified 54 patients diagnosed with plasmablastic neoplasms including PBM (31%, N=17) and PBL (63%, N=34) between January 2017 and May 2022. The median age at diagnosis was 54 years (range 17-91 years) and 78% were male. Hispanic patients represented 70% (N=36) of our total study population. Predisposing immunosuppression was identified in 65% (N=34), including 33% (N=17) on immunosuppressive drugs and 52% (N=27) with non-iatrogenic causes; 38% (N=18) of patients were HIV-positive. Pathologic analysis showed EBER positivity of 44% (N=24), CD138 positivity of 90%, and c-myc positivity of 87%. The most common initial regimens were EPOCH (17%, N=9) and V-EPOCH (33%, N=18). There was no superiority when comparing V-EPOCH versus all other treatment regimens. Seven patients received subsequent consolidation with high-dose chemotherapy followed by autologous hematopoietic transplant. Seven patients were lost to follow-up prior to initia