Efficacy of Daratumumab-Based Regimens for the Treatment of Plasma Cell Leukemia

Current Status on Management of Primary Plasma Cell Leukemia

PURPOSEOF REVIEW

Plasma Cell Leukemia (PCL) is a very rare and highly aggressive form of plasma cell dyscrasia. This review seeks to evaluate the outcomes of PCL in the context of combination novel agent therapy and stem cell transplant (SCT) protocols.

RECENT FINDINGS

The diagnostic criteria for PCL have now evolved to include patients with 5% circulating PC. While management remains challenging, the incorporation of novel agent-based induction regimen has significantly improved early mortality and reduced attrition of patients proceeding to SCT. In recent prospective clinical trials, patients with PCL demonstrated an overall response rates of 69% to 86%, with progression-free and overall survival ranging from 13.8 to 15.5 months and 24.8 to 36.3 months, respectively. B-cell lymphoma 2 (BCL2) inhibitors, such as venetoclax present a targeted intervention opportunity for patients with PCL with t(11;14). Dedicated clinical trials tailored to PCL are crucial, integrating newer therapies in the frontline setting to further optimize responses and enhance overall outcomes.

Single-Center Experience of Patients with Plasma Cell Leukemia in the Era of New Therapeutics

INTRODUCTION

Plasma cell leukemia (PCL) can occur de novo as primary PCL (pPCL), or in patients with prior diagnosis of multiple myeloma (MM) as secondary PCL (sPCL). In 2021, the diagnostic criteria have been revised, establishing a new cut-off of ≥5% plasma cells in the peripheral blood. Lacking specific clinical trials, PCL is treated similarly to MM; however, outcome for patients with PCL remains poor. Here, we report outcomes for patients with pPCL and sPCL in the era of novel agents.

METHODS

We performed a retrospective analysis and identified 19 patients (11 pPCL, 8 sPCL) who have been treated for PCL between 2010 and 2022 at University Hospital Essen.

RESULTS

Patients with pPCL had a median overall survival (OS) of 37.8 months (95% CI: [15.4; 52.3] months) from diagnosis, with a median time to next treatment (TTNT) of 18.4 (2.0; 22.9) months. All patients were treated with a proteasome-inhibitor (PI)-based induction therapy, and the majority was consolidated with an autologous stem cell transplantation (SCT). Five of these patients received a tandem transplantation. Patients with sPCL had a median OS of only 1.5 months after diagnosis of PCL. Only 1 patient achieved a remission with daratumumab and subsequent allogenic SCT.

CONCLUSION

With our study, we add evidence for a PI-based induction therapy followed by a consolidating autologous SCT for patients with pPCL and give further evidence that a tandem transplant concept might be beneficial. The diagnosis of sPCL remains devastating and needs new therapeutic approaches.

The Current State of Knowledge About Evolution of Multiple Myeloma to Plasma Cell Leukemia

Plasma cell leukemia is a rare form of multiple myeloma (MM). In contrast to de novo primary plasma cell leukemia (pPCL), which is very uncommon presentation of MM, there is increasing frequency of transformation to secondary plasma cell leukemia (sPCL) with increasing survival of patients (MM). The molecular basis of sPCL remains poorly understood sPCL is particularly aggressive and is associated with an extremely poor prognosis, constituting a major unmet medical need. High-quality data in sPCL regarding presentation, treatment and outcomes is limited. Herein we review the current state of knowledge on sPCL diagnostics, molecular biology, clinical characteristics, prognosis and reported treatment outcomes and the emergence of the new therapeutic strategies.

Case report: Plasma cell leukemia secondary to multiple myeloma successfully treated with anti-BCMA CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy provides an effective salvage treatment for relapsed/refractory multiple myeloma (RRMM) patients. End-stage RRMM with plasma cell leukemia (PCL) transformation is highly aggressive and resistant to conventional therapy. There is an urgent need for new therapeutics and CAR-T therapy may play an important role. We report a case of PCL secondary to RRMM successfully treated with CAR-T cell therapy targeting B-cell maturation antigen (BCMA). A woman was diagnosed as having MM 4 years ago and progressed to secondary PCL (sPCL) of five prior lines of treatment including proteasome inhibitors, an immunomodulatory agent, cytotoxic drugs, and an anti-CD38 monoclonal antibody. After receiving a BCMA CAR-T therapy, she achieved a stringent complete response that lasted 9 months. Then, the patient irregularly took venetoclax 10 mg per day due to a slightly higher λ FLC concentration, which did not meet the criteria for progression. She maintained a complete response for the following 7 months. In conclusion, BCMA CAR-T therapy may be a promising therapeutic approach in PCL patients. More studies are needed to evaluate the benefit of anti-BCMA CAR-T therapy in PCL patients.

Clinical Trial Registration:www.chictr.org.cn, ChiCTR1900024388, Registered 9 July 2019.