Outcomes of hematopoietic stem cell transplantation in primary plasma cell leukemia: A systematic review and meta-analysis.

BACKGROUND

Hematopoietic stem cell transplantation (HCT) is a pivotal treatment modality for primary plasma cell leukemia (pPCL). We aimed to examine the outcomes of allogeneic (allo) and autologous (auto) HCT in adult pPCL patients.

METHODS

Following PRISMA guidelines, a comprehensive literature search was performed on PubMed, Cochrane, Embase, and Clinicaltrials.gov using relevant MeSH terms and keywords. Twelve original articles reporting outcomes of auto-HCT or allo-HCT in adult pPCL patients were included. The pooled analysis was performed using the 'meta' package in the R program (version 4.3.0).

RESULTS

Our analysis included 1757 pPCL patients (1535 with auto-HCT, 222 with allo-HCT), and 49 % were males. The pooled 3 years overall survival (OS), progression-free survival/event-free survival (PFS/EFS), and relapse rate (RR) in auto-HCT were 51 % (95 % CI 0.4-0.61, I=92 %, p = <0.01), 36 % (95 % CI 0.24-0.52, I 2 =97 %, p < 0.01), and 68 % (95 % CI, 0.65-0.71, I2=0 %, p = 0.42), respectively. Among allo-HCT recipients, the reported OS varied from 71 % at 2.3 years to 31 % at 4 years and EFS/PFS from 29 % at 2.5 years to 19 % at 4 years. The pooled treatment-related mortality (TRM) was 12 % (95 % CI 0.05-0.25, I =35 %, p = 0.22) at a median of 6 months. The pooled incidence of acute and chronic graft versus host disease was 27 % (0.19-0.36, I= 30 %, p = 0.21) and 36 % (0.27-0.45, I= 24 %, p = 0.26), respectively.

CONCLUSION

HCT remains pivotal in treating primary plasma cell leukemia. However, higher relapse rates warrant novel agents and clinical trials to improve transplant-related outcomes in this challenging subgroup.