Transplantation Strategies in Treatment of Primary Plasma Cell Leukemia in Germany-A Multi-Center Analysis.

OBJECTIVES

Primary plasma cell leukemia (pPCL) is a rare disease with poor outcomes. As data on randomized phase-III trials are lacking, treatment recommendations are predominately based on retrospective analyses incorporating time periods with outdated therapies. Thus, the optimal consolidation strategy remains to be defined.

METHODS

We conducted a retrospective, multi-center analysis with 49 transplant-eligible patients diagnosed with pPCL between 2011 and 2025 focusing on different stem cell transplantation (SCT) strategies as consolidation treatment in first remission: single autologous (auto) or single allogeneic (allo) SCT versus patients with tandem cell therapy strategies (auto-auto, allo-auto, auto-chimeric antigen receptor therapy).

RESULTS

The median follow-up after first SCT was 31 months. The cumulative incidence of initiating next treatment was lower after tandem cell therapy compared to single SCT (at 12 months: 42% vs. 57%, p = 0.006). Moreover, in a multivariable analysis incorporating cytogenetic risk and response to induction therapy, tandem transplantation strategies tended to be the only independent predictor for prolonged time to next treatment (TTNT, p = 0.077). Noteworthy, differences in TTNT between patients with a single SCT and patients with tandem cell therapy did not translate into an improved overall survival, possibly due to potent salvage therapies.

CONCLUSIONS

Our data support recent recommendations advising treating patients with tandem transplantation regimes.