How I treat plasma cell leukemia

Plasma cell leukemia with soft tissue involvement; reporting a rare case

Plasma cell leukemia (PCL) is a rare aggressive variant of multiple myeloma. PCL is diagnosed when clonal plasma cells constitute more than 20 % of the total circulating leukocytes or when the absolute plasma cell count exceeds 2 × 109 /L. Extramedullary involvement including cavity effusion is frequently seen at the time of diagnosis. However, soft tissue involvement is rarely encountered with only one published case in the English literature. We report a 74-year-old man, who presented with progressive shortness of breath over a few months. Laboratory studies showed leukocytosis (32 × 109 /L) with 26 % peripheral plasmacytoid cells and significantly elevated lactate dehydrogenase (> 2500 U/L). Serum protein electrophoresis detected a monoclonal IgG lambda band. A 7.4 cm left hilar mass, bilateral pleural effusion, and multiple fluorodeoxyglucose (FDG)-avid subcutaneous nodules in the pelvic and gluteal regions were demonstrated on imaging. Gluteal nodule biopsy revealed diffuse infiltrative CD138+ and MUM1+ cells with aberrant CD4, CD30, and BCL2 expression. The Ki-67 proliferation index was 70 %. Bone marrow biopsy showed sheets of atypical plasma cells with lambda-restriction and CD138 and MUM1 expression without cyclin D1 and CD20 expression. These cells comprise approximately 70-80 % of the bone marrow cellularity. A similar immunophenotype was demonstrated in peripheral and bone marrow flow cytometry. Molecular and cytogenetics showed an abnormal clone with a complex karyotype including monosomy 13 and 14q deletion. Overall, these findings are consistent with a plasma cell neoplasm. Our case study illustrates soft tissue involvement in PCL, which is rarely seen.

Treatment of primary plasma cell leukaemia with carfilzomib and lenalidomide-based therapy (EMN12/HOVON-129): final analysis of a non-randomised, multicentre, phase 2 study

BACKGROUND

Primary plasma cell leukaemia is a rare and aggressive plasma cell disorder with a poor prognosis. The aim of the EMN12/HOVON-129 study was to improve the outcomes of patients with primary plasma cell leukaemia by incorporating carfilzomib and lenalidomide in induction, consolidation, and maintenance therapy.

METHODS

The EMN12/HOVON-129 study is a non-randomised, phase 2, multicentre study conducted at 19 academic centres and hospitals in seven European countries (Belgium, Czech Republic, Denmark, Italy, Norway, The Netherlands, and the UK) for previously untreated patients with primary plasma cell leukaemia aged 18 years or older. Inclusion criteria were newly diagnosed primary plasma cell leukaemia (defined as >2 ×109 cells per L circulating monoclonal plasma cells or plasmacytosis >20% of the differential white cell count) and WHO performance status 0-3. Patients aged 18-65 years (younger patients) and 66 years or older (older patients) were treated in age-specific cohorts and were analysed separately. Younger patients were treated with four 28-day cycles of carfilzomib (36 mg/m2 intravenously on days 1, 2, 8, 9, 15, and 16), lenalidomide (25 mg orally on days 1-21), and dexamethasone (20 mg orally on days 1, 2, 8, 9, 15, 16, 22, and 23). Carfilzomib-lenalidomide-dexamethasone (KRd) induction was followed by double autologous haematopoietic stem-cell transplantation (HSCT), four cycles of KRd consolidation, and then maintenance with carfilzomib (27 mg/m2 intravenously on days 1, 2, 15, and 16 for the first 12 28-day cycles, and then 56 mg/m2 on days 1 and 15 in all subsequent cycles) and lenalidomide (10 mg orally on days 1-21) until progression. Patients who were eligible for allogeneic HSCT, could also receive a single autologous HSCT followed by reduced-intensity conditioning allogeneic HSCT and then carfilzomib-lenalidomide maintenance. Older patients received eight cycles of KRd induction followed by maintenance therapy with carfilzomib and lenalidomide until progression. The primary endpoint was progression-free survival. The primary analysis population was the intention-to-treat population, irrespective of the actual treatment received. Data from all participants who received any study drug were included in the safety analyses. The trial was registered at www.trialregister.nl (until June 2022) and https://trialsearch.who.int/ as NTR5350; recruitment is complete and this is the final analysis.

FINDINGS

Between Oct 23, 2015, and Aug 5, 2021, 61 patients were enrolled and received KRd induction treatment (36 patients aged 18-65 years [20 (56%) were male and 16 (44%) female], and 25 aged ≥66 years [12 (48%) were male and 13 (52%) female]). With a median follow-up of 43·5 months (IQR 27·7-67·8), the median progression-free survival was 15·5 months (95% CI 9·4-38·4) for younger patients. For older patients, median follow-up was 32·0 months (IQR 24·7-34·6), and median progression-free survival was 13·8 months (95% CI 9·2-35·5). Adverse events were most frequently observed directly after treatment initiation, with infections (two of 36 (6%) younger patients and eight of 25 (32%) older patients) and respiratory events (two of 36 [6%] younger patients and four of 25 [16%] older patients) being the most common grade 3 or greater events during the first four KRd cycles. Treatment-related serious adverse events were reported in 26 (72%) of 36 younger patients and in 19 (76%) of 25 older patients, with infections being the most common. Treatment-related deaths were reported in none of the younger patients and three (12%) of the older patients (two infections and one unknown cause of death).

INTERPRETATION

Carfilzomib and lenalidomide-based therapy provides improved progression-free survival compared with previously published data. However, results remain inferior in primary plasma cell leukaemia compared with multiple myeloma, highlighting the need for new studies incorporating novel immunotherapies.

FUNDING

Dutch Cancer Society, Celgene (a BMS company), and AMGEN.

Plasma Cell Leukemia-Clinicopathological Profile from a Tertiary Care Center in Western India

Poornima ManimaranIntroduction  Plasma cell leukemia (PCL) is very uncommon and aggressive neoplasm constituting 2 to 4% of all plasma cell dyscrasias. By definition, clonal plasma cells should make up 20% of peripheral blood or have an absolute plasma cell count of 2 × 10 9 cells/cu.mm. PCL can be primary or secondary. In this study, the clinicohematological features of PCL, and correlation of immunophenotypic profile and conventional therapies with overall survival was analyzed. Materials and Methods  This retrospective study involved PCL patients who were diagnosed across a 12-year period, from 2010 to 2021, at a tertiary care center in western India. Clinical, biochemical, peripheral smear, bone marrow aspirate, immunophenotyping, and molecular analysis were performed. Results  Total 39 PCL patients were included in the study among which 36 were primary PCL patients. Splenomegaly (10/27), hepatomegaly (6/26), and lymphadenopathy (5/23) were noted. At presentation, all patients had anemia (<11g/dL), thrombocytopenia (33/39), hypercalcemia (>11mg/dl) 10/33 (30.3%) and lytic lesions was noted in 18/26 (69.2%). Immunophenotype of these patients showed CD 38 positivity, CD 138 positivity, CD56 positivity, and CD 117 negativity were 100, 62, 41.6, and 89%, respectively. Overall survival of our patients was 4.1 months and overall survival of patients treated with VTD (bortezomib, thalidomide, dexamethasone) and VCD (bortezomib, cyclophosphamide, dexamethasone) regimen was 3.4 and 4.1 months, respectively, which was not statically significant ( p -value 0.816). CD117 and CD56 markers were also not having any prognostic significance ( p -value 1.000 and 0.873, respectively). Conclusion  Because of rarity of the disease, prospective studies are very limited and hence management and outcome of the disease are difficult to analyze. The current treatment protocols have no survival advantage and hence newer therapeutic approach is mandatory to attain better outcome.

IgE Plasma Cell Leukemia Harboring t(11;14) and 1q Amplification

IgE plasma cell neoplasm is the rarest subtype of plasma cell neoplasms and is known for its poor prognosis and high incidence of t(11;14). However, t(11;14) has been classified as a standard-risk rather than high-risk cytogenetic abnormality in multiple myeloma. We have been unable to explain the discrepancy that the hallmark of IgE plasma cell neoplasm with a poor prognosis is a standard-risk cytogenetic abnormality. Here, we report a case of IgE primary plasma cell leukemia with extramedullary lesions of the liver, stomach, and lymph nodes. Plasma cell infiltration was pathologically confirmed in each organ. Cytogenetic analysis of plasma cells revealed t(11;14) and amplification of 1q21. Chemotherapy, with immunomodulatory imide drugs, proteasome inhibitors, and CD38 antibodies, was unsuccessful. In IgE plasma cell neoplasm, coexistence of other cytogenetic abnormalities with t(11;14) may be important. Investigating the presence of cytogenetic abnormalities coexisting with t(11;14) is not only useful for evaluating prognosis but also important for understanding the pathogenesis of the disease. Recently, venetoclax, an oral BCL2 inhibitor, has demonstrated promising efficacy in plasma cell neoplasm patients harboring t(11;14). Development of an effective venetoclax-based regimen for treating aggressive IgE plasma cell neoplasm with t(11;14) is expected.

How We Manage Newly Diagnosed Multiple Myeloma With Circulating Tumor Cells

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.Careful evaluation of peripheral blood for the presence of circulating plasma cells by morphologic assessment or by flow cytometric analysis is an essential component of the diagnostic workup in all patients with newly diagnosed multiple myeloma (MM) to timely differentiate between MM and primary plasma cell leukemia (pPCL), which is the most aggressive plasma cell dyscrasia. The improvement in survival over time is more modest in pPCL, compared with what has been achieved in MM. pPCL is currently defined by the presence of ≥ 5% circulating plasma cells. However, this cutoff is now challenged by new data, from three large cohorts of patients with newly diagnosed MM, showing that a threshold of 2% circulating tumor cells (CTCs) by flow cytometry can be used to identify a subset of patients with ultra-high-risk MM with comparable prognosis as patients with pPCL. These patients may benefit from more intensified first-line therapies, or from enrollment into specific clinical trials, designed for ultra-high-risk MM and pPCL. Apart from differentiating MM from pPCL, the quantification of CTCs is also useful for risk stratification in MM. The detection of CTCs above a threshold of 0.01%-0.07% (much lower than the threshold to define pPCL) appears to be an independent predictor of poor clinical outcomes in newly diagnosed MM. Additional studies, including transplant-ineligible patients or with incorporation of novel immunotherapies, are needed to identify a definitive prognostic CTC cutoff. The next step will be the incorporation of CTC detection into existing staging systems to improve risk stratification and treatment personalization.

Clinicopathological and laboratory parameters of plasma cell leukemia among Indian population

BACKGROUND

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell neoplasm distinguished by extensive clonal expansion of plasma cells in the bone marrow (BM) and peripheral blood (PB). PCL is divided into two subtypes: primary (pPCL) originates de novo without preceding multiple myeloma, while secondary (sPCL) comprises a leukemic modification that occurs as a late manifestation from previous multiple myeloma (MM). pPCL and sPCL are clinically and biologically two different entities. The molecular mechanisms of the development of PCL, either primary or secondary, remain poorly understood. We aim to present 5 years of data on clinical profiles and treatment outcomes of pPCL and sPCL patients treated at our cancer hospital in India and to find a predictive parameter of the development of PCL in cases of MM.

METHODS

In this study, we retrospectively reviewed and evaluated the clinicopathological features, laboratory parameters, immunophenotypic profile, and patient outcomes of 17 PCL cases diagnosed among 180 plasma cell dyscrasia patients during the study period to establish a correlation between pPCL & sPCL for diagnosis and management of PCL.

RESULTS

A total of 17 PCL patients were diagnosed among 180 plasma cell dyscrasia patients during the study period. Among PCL patients, 9 cases had pPCL (52.94% of all PCL patients), and 8 cases had sPCL (47.06% of all PCL patients). Peculiar differences were seen between the two PCL types. Both types of PCL had a younger age at the time of diagnosis, having elevated BM plasma cell infiltration percentage, frequent anemia, thrombocytopenia, elevated beta-2-microglobulin (B2M) levels, raised LDH levels, and positive M-protein in both serum and urine. In addition, SFLC assay and Immunofixation assay showed higher κ and lower λ in pPCL compared with sPCL (P<0.05). Higher Renal insufficiency was also observed in pPCL compared to sPCL (P=0.335). The survival and response to treatment of PCL patients remain considerably poor, sPCL exhibit shorter overall survival (OS) than pPCL with (median 1.75 months vs. 7 months respectively, P=0.1682). Plasma cell leukemia (PCL) needs to be diagnosed early and requires prompt initiation of treatment before patients get complications.

CONCLUSION

Our study characterizes the clinical and laboratory features of pPCL and sPCL and may aid physicians in prognosticating the course of disease of their patients. However, future multicentre studies are the need of the hour to develop accurate diagnostic criteria and establish the efficacy of therapeutic regimens.

The clinical characteristics and prognosis of patients with primary plasma cell leukemia (pPCL) according to the new IMWG definition criteria

Recently, the definition of primary plasma cell leukemia (pPCL) has been revised as the presence of circulating plasma cells (CPCs) ≥5% in peripheral blood smear. Consequently, the clinical features and prognosis of this aggressive disease can be truly identified by the larger patient cohort. Herein, we identified 158 new-defined pPCL patients among 2,266 MM patients (7.0%), and such prevalence doubled the previous estimate. Our study firstly provided solid support for the application of the new definition. We also found that cytopenias and adverse prognostic biomarkers were more common in new-defined pPCL compared with MM (p < 0.05). Besides, the patients receiving proteasome inhibitors based regimen in combination with stem cell transplantation could experience a considerable survival benefit. Strikingly, we showed that the presence of conventional high-risk cytogenetic abnormalities in pPCL didn't exert a great prognostic effect like MM, while elevated LDH reflecting tumor cells proliferation rate was the only independent predictor.

Validation of the revised diagnostic criteria for primary plasma cell leukemia by the Korean Multiple Myeloma Working Party

The International Myeloma Working Group has recently revised the diagnostic criteria for primary plasma cell leukemia (PCL) to circulating plasma cells (CPCs) ≥ 5% in a peripheral blood smear. The present study validated new criteria in patients with multiple myeloma or PCL diagnosed using the previous diagnostic criteria, who were administered immunomodulatory drugs or proteasome inhibitors as induction therapy. We analyzed the medical records of 1357 patients from eight hospitals in South Korea. The median age of the all patients was 64 years, and 187 (13.8%) had CPCs at diagnosis. Only 79 (5.8%) of the patients had ≥ 5% CPCs. The median overall survival (OS) of patients with CPCs ≥ 5% and ≥ 20% was similar, but had significantly inferior median progression-free survival (PFS) and median OS than those with CPCs < 5% (13.1 vs. 21.5 months, P < 0.001, and 21.5 vs. 60.9 months, P < 0.001, respectively). Primary PCL diagnosed using the revised criteria presented with higher total calcium levels and serum creatinine levels, lower platelet counts and frequent organomegaly and plasmacytoma at diagnosis. Univariate and multivariate analyses demonstrated that the presence of plasmacytoma and elevated serum β2-microglobulin were significantly associated with OS in primary PCL. In conclusion, the revised criterion of CPCs ≥ 5% in a peripheral blood smear is appropriate for PCL diagnosis.

Update on primary plasma cell leukemia

Plasma cell leukemia (PCL) is a rare and highly aggressive plasma cell neoplasm developing in 0.5?4% of patients with multiple myeloma (MM). The diagnostic criteria were recently revised from 20% to ≥5% of circulating plasma cells in peripheral blood smears. PCL is classified as primary or secondary; primary PCL is when it presents in patients with no MM. Primary PCL shows clinical and laboratory features at presentation that differ from MM and exhibits a dismal prognosis even with the use of effective agents against MM. Therefore, intensive chemotherapy should be initiated immediately after diagnosis, and autologous stem cell transplantation is recommended for transplant-eligible patients. Maintenance therapy after transplantation may reduce the rate of early relapses. We reviewed the definitions of PCL, revised diagnostic criteria, clinical features, and appropriate initial treatments for primary PCL.

Identification of High-Risk Multiple Myeloma With a Plasma Cell Leukemia-Like Transcriptomic Profile

Primary plasma cell leukemia (pPCL) is an aggressive subtype of multiple myeloma, which is distinguished from newly diagnosed multiple myeloma (NDMM) on the basis of the presence of ≥ 20% circulating tumor cells (CTCs). A molecular marker for pPCL is currently lacking, which could help identify NDMM patients with high-risk PCL-like disease, despite not having been recognized as such clinically.

Primary plasma cell leukemia: consensus definition by the International Myeloma Working Group according to peripheral blood plasma cell percentage

Primary plasma cell leukemia (PCL) has a consistently ominous prognosis, even after progress in the last decades. PCL deserves a prompt identification to start the most effective treatment for this ultra-high-risk disease. The aim of this position paper is to revisit the diagnosis of PCL according to the presence of circulating plasma cells in patients otherwise meeting diagnostic criteria of multiple myeloma. We could identify two retrospective series where the question about what number of circulating plasma cells in peripheral blood should be used for defining PCL. The presence of ≥5% circulating plasma cells in patients with MM had a similar adverse prognostic impact as the previously defined PCL. Therefore, PCL should be defined by the presence of 5% or more circulating plasma cells in peripheral blood smears in patients otherwise diagnosed with symptomatic multiple myeloma.

LncRNAs LY86-AS1 and VIM-AS1 Distinguish Plasma Cell Leukemia Patients from Multiple Myeloma Patients

Long non-coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides. Due to modern genomic techniques, the involvement of lncRNAs in tumorigenesis has been revealed; however, information concerning lncRNA interplay in multiple myeloma (MM) and plasma cell leukemia (PCL) is virtually absent. Herein, we aimed to identify the lncRNAs involved in MM to PCL progression. We investigated representative datasets of MM and PCL patients using next-generation sequencing. In total, 13 deregulated lncRNAs (p < 0.00025) were identified; four of them were chosen for further validation in an independent set of MM and PCL patients by RT-qPCR. The obtained results proved the significant downregulation of lymphocyte antigen antisense RNA 1 (LY86-AS1) and VIM antisense RNA 1 (VIM-AS1) in PCL compared to MM. Importantly, these two lncRNAs could be involved in the progression of MM into PCL; thus, they could serve as promising novel biomarkers of MM progression.

Correlation of CD38 expression with the progression of hemorrhagic fever with renal syndrome

To assess the relationship between the expression of CD38 and the progression of hemorrhagic fever with renal syndrome (HFRS), we determined the levels of CD38 during different phases of HFRS and evaluated the relationship between changes in CD38 expression and the progression of HFRS. The expression of CD38 in 68 patients with HFRS was analyzed by flow cytometry, and this method was also used to determine the levels of CD4⁺T, CD8⁺T, and B lymphocytes and NK cells. Furthermore, creatinine (Cr), uric acid (UA), and urea in serum at each stage of HFRS were measured using commercial kits. The basic clinical reference values for leukocytes, platelets (PLT), and red blood cells were determined by conventional methods. The colloidal gold method was used to measure HFRS antibody levels in the patients. A significant change in CD38 expression was observed from the fever phase to the recovery phase in patients with HFRS. Moreover, the expression of CD38 was proportionally correlated with the levels of Cr, UA, and urea in serum. In contrast, there was an inverse correlation between CD38 and PLT. Interestingly, an increase in CD38 expression correlated with an increase in CD8⁺T lymphocytes, B cells, and NK cells, but with a decrease in CD4⁺T lymphocytes. The expression of CD38 is associated with the progression of HFRS, suggesting that it may be a potent indicator of the stages of this disorder.

Preclinical activity and determinants of response of the GPRC5DxCD3 bispecific antibody talquetamab in multiple myeloma

Cell surface expression levels of GPRC5D, an orphan G protein-coupled receptor, are significantly higher on multiple myeloma (MM) cells, compared with normal plasma cells or other immune cells, which renders it a promising target for immunotherapeutic strategies. The novel GPRC5D-targeting T-cell redirecting bispecific antibody, talquetamab, effectively kills GPRC5D+ MM cell lines in the presence of T cells from both healthy donors or heavily pretreated MM patients. In addition, talquetamab has potent anti-MM activity in bone marrow (BM) samples from 45 patients, including those with high-risk cytogenetic aberrations. There was no difference in talquetamab-mediated killing of MM cells from newly diagnosed, daratumumab-naïve relapsed/refractory (median of 3 prior therapies), and daratumumab-refractory (median of 6 prior therapies) MM patients. Tumor cell lysis was accompanied by T-cell activation and degranulation, as well as production of pro-inflammatory cytokines. High levels of GPRC5D and high effector:target ratio were associated with improved talquetamab-mediated lysis of MM cells, whereas an increased proportion of T cells expressing PD-1 or HLA-DR, and elevated regulatory T-cell (Treg) counts were associated with suboptimal killing. In cell line experiments, addition of Tregs to effector cells decreased MM cell lysis. Direct contact with bone marrow stromal cells also impaired the efficacy of talquetamab. Combination therapy with daratumumab or pomalidomide enhanced talquetamab-mediated lysis of primary MM cells in an additive fashion. In conclusion, we show that the GPRC5D-targeting T-cell redirecting bispecific antibody talquetamab is a promising novel antimyeloma agent. These results provide the preclinical rationale for ongoing studies with talquetamab in relapsed/refractory MM.

Clinical Characteristics and Outcomes of Patients With Primary Plasma Cell Leukemia in the Era of Novel Agent Therapy

OBJECTIVE

To evaluate the clinical outcomes of patients with primary plasma cell leukemia (pPCL) defined by 5% or greater clonal circulating plasma cells on peripheral blood smear and treated with novel agent induction therapies.

PATIENTS AND METHODS

A cohort of 68 patients with pPCL diagnosed at the Mayo Clinic in Rochester, Minnesota, from January 1, 2000, to December 31, 2019, and treated with novel agent induction therapies was evaluated.

RESULTS

The median follow-up was 46 (95% CI, 41 to 90) months. The median bone marrow plasma cell content was 85% (range, 10% to 100%) and median clonal circulaitng plasma cell percentage on the peripheral blood smear was 26% (range, 5% to 93%). There was a preponderance of t(11;14) primary cytogenetic abnormality in this cohort. The median time to next therapy (TTNT) and overall survival (OS) for all patients with pPCL patients in this cohort was 13 (95% CI, 9 to 17) and 23 (95% CI, 19 to 38) months, respectively. However, when stratified by cytogenetic risk, the median TTNT and OS were 16 and 51 months for standard risk vs 9 and 19 months for high risk (P=.01 for OS).

CONCLUSION

Primary plasma cell leukemia remains an aggressive disease with poor prognosis despite novel agent-based therapies. Some patients have better than expected survival and this phenomenon may be influenced by the absence of high-risk cytogenetics. Newer treatment regimens are needed to improve the prognosis of this devastating disease.

A clinical perspective on plasma cell leukemia; current status and future directions

Primary plasma cell leukemia (pPCL) is an aggressive plasma cell disorder with a guarded prognosis. The diagnosis is confirmed when peripheral blood plasma cells (PCs) exceed 20% of white blood cells or 2000/μL. Emerging data demonstrates that patients with lower levels of circulating (PCs) have the same adverse prognosis, challenging the clinical disease definition, but supporting the adverse impact of circulating PCs. The cornerstone of treatment consists of combination therapy incorporating a proteasome inhibitor, an immunomodulatory agent, steroids, and/or anthracyclines and alkylators as part of more-intensive chemotherapy, followed by consolidative autologous hematopoietic cell transplantation in eligible patients and then maintenance therapy. Monoclonal antibodies are also currently being evaluated in this setting with a strong rationale for their use based on their activity in multiple myeloma (MM). Due to limited therapeutic studies specifically evaluating pPCL, patients with pPCL should be considered for clinical trials. In contrast to MM, the outcomes of patients with pPCL have only modestly improved with novel therapies, and secondary PCL arising from MM in particular is associated with a dismal outlook. Newer drug combinations, immunotherapy, and cellular therapy are under investigation, and these approaches hopefully will demonstrate efficacy to improve the prognosis of pPCL.

Multiple myeloma

Multiple myeloma is the second most common haematological malignancy in high-income countries, and typically starts as asymptomatic precursor conditions-either monoclonal gammopathy of undetermined significance or smouldering multiple myeloma-in which initiating genetic abnormalities, such as hyperdiploidy and translocations involving the immunoglobulin heavy chain, are already present. The introduction of immunomodulatory drugs, proteasome inhibitors, and CD38-targeting antibodies has extended survival, but ultimately the majority of patients will die from their disease, and some from treatment-related complications. Disease progression and subsequent relapses are characterised by subclonal evolution and increasingly resistant disease. Patients with multiple myeloma usually have hypercalcaemia, renal failure, anaemia, or osteolytic bone lesions-and a detailed diagnostic investigation is needed to differentiate between symptomatic multiple myeloma that requires treatment, and precursor states. Risk stratification using both patient-specific (eg, performance status) and disease-specific (eg, presence of high-risk cytogenetic abnormalities) is important for prognosis and to define the best treatment strategy. Current research strategies include the use of minimal residual disease assays to guide therapy, refining immunotherapeutic approaches, and intercepting disease early in smouldering multiple myeloma.

CD38: targeted therapy in multiple myeloma and therapeutic potential for solid cancers

INTRODUCTION

CD38 is expressed by some cells of hematological malignancies and tumor-related immunosuppressive cells, including regulatory T cells, regulatory B cells, and myeloid-derived suppressor cells. CD38 is an effective target in some hematological malignancies such as multiple myeloma (MM). Daratumumab (Dara), a CD38-targeting antibody, can eliminate CD38^high immune suppressor cells and is regarded as a standard therapy for MM because of its outstanding clinical efficacy. Other CD38 monospecific antibodies, such as isatuximab, MOR202, and TAK079, showed promising effects in clinical trials.

AREA COVERED

This review examines the expression, function, and targeting of CD38 in MM and its potential to deplete immunosuppressive cells in solid cancers. We summarize the distribution and biological function of CD38 and discuss the application of anti-CD38 drugs in hematological malignancies. We also analyz the role of CD38⁺ immune cells in the tumor microenvironment to encourage additional investigations that target CD38 in solid cancers. PubMed and ClinicalTrials were searched to identify relevant literature from the database inception to 30 April 2020.

EXPERT OPINION

There is convincing evidence that CD38-targeted immunotherapeutics reduce CD38⁺ immune suppressor cells. This result suggests that CD38 can be exploited to treat solid tumors by regulating the immunosuppressive microenvironment.

Plasma Cell Leukemia - Facts and Controversies: More Questions than Answers?

Plasma cell leukemia (PCL) is an aggressive hematological malignancy characterized by an uncontrolled clonal proliferation of plasma cells (PCs) in the bone marrow and peripheral blood. PCL has been defined by an absolute number of circulating PCs exceeding 2.0 × 10⁹/L and/or >20% PCs in the total leucocyte count. It is classified as primary PCL, which develops de novo, and secondary PCL, occurring at the late and advanced stages of multiple myeloma (MM). Primary and secondary PCL are clinically and biologically two distinct entities. After the diagnosis, treatment should be immediate and should include a proteasome inhibitor and immunomodulator-based combination regimens as induction, followed by stem cell transplantation (SCT) in transplant-eligible individuals who have cleared the peripheral blood of circulating PCs. Due to the rarity of the condition, there have been very few clinical trials. Furthermore, virtually all of the myeloma trials exclude patients with active PCL. The evaluation of response has been defined by the International Myeloma Working Group and consists of both acute leukemia and MM criteria. With conventional chemotherapy, the prognosis of primary PCL has been ominous, with reported overall survival (OS) ranging from 6.8 to 12.6 months. The use of novel agents and autologous SCT appears to be associated with deeper response and an improved survival, although it still remains low. The PCL prognostic index provides a simple score to risk-stratify PCL. The prognosis of secondary PCL is extremely poor, with OS of only 1 month.

Secondary Plasma Cell Leukemia: A Case Report

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma and has a poor prognosis. It needs prompt recognition in order to institute timely treatment. Given its relatively low incidence, it is an evolving area of research as well. This case report describes a patient with PCL in the setting of a previously treated myeloma. The report also reviews the clinicopathologic, cytogenetic, and immunophenotypic characteristics of PCL and its management.

Secondary Plasma Cell Leukemia in a Recurrent Multiple Myeloma: Rare Case Scenario

Plasma cell leukemia (PCL) is an aggressive hematological condition characterized by the presence of plasma cells in the peripheral smear. It presents as de novo or may arise from multiple myeloma (MM), and hence is diagnosed as primary or secondary PCL, respectively. We report a case of 79-year-old patient diagnosed with MM two years prior to the admission to our institution with prior treatment with bortezomib, lenalidomide and dexamethasone (VRD) and daratumumab, pomalidomide and dexamethasone. Morphologic examination and flow cytometry studies performed on the peripheral smear demonstrated 45%-55% small to medium atypical plasma cells showing a kappa restriction and dim CD138 expression on flow cytometry analysis. The patient was started on brentuximab vedotin, etoposide, cytoxan and dexamethasone, which resulted in near complete elimination of the atypical plasma cells from the peripheral smear one week after the completion of two cycles. He received three cycles of brentuximab vedotin with a gradual decrease in serum free light chain. However, he eventually developed lethargy, weakness and seizures. The involvement of the central nervous system (CNS) by MM was confirmed with MRI, flow cytometry and cytology of cerebrospinal fluid. The treatment with whole brain radiation and ibrutinib was initiated. Our case report highlights the rare case of aggressive clinical course of MM leading to the development of plasmacytoma of kidney, secondary PCL and eventually spreading to the CNS.

Primary Plasma Cell Leukemia: Real-World Retrospective Study of 46 Patients From a Single-Center Study in China

BACKGROUND

Primary plasma cell leukemia (PPCL) is a rare and aggressive plasma cell disorder. The use of novel agents, together with autologous stem cell transplantation, has improved survival outcome in PPCL. However, the prognosis is still very poor, and the optimal treatment remains an unmet clinical need.

PATIENTS AND METHODS

We studied the efficacy and prognostic impact of novel agents in 46 patients with PPCL patients at the Blood Diseases Hospital in China. We examined the impact of clinical and laboratory features, as well as therapies (bortezomib- and/or immunomodulatory drug-based therapies, chemotherapy) on survival and extent of clinical response, including progression-free survival and overall survival (OS). Progression-free survival and OS were assessed by the Kaplan-Meier method, and survival distributions were compared by log-rank test.

RESULTS

In our cohort of 46 PPCL patients, the median age at the time of diagnosis was 54 years. Overall response rate was 54% (25/46). The median (95% confidence interval) progression-free survival time was 6 (0-12.5) months, and OS time was 14 (4.6-23.4) months. The OS time was significantly longer in patients treated with bortezomib-based versus non-bortezomib-based therapies (median [95% confidence interval], 19 [9-28.9] vs. 5 [4-24] months; P = .019).

CONCLUSION

This large single-center study of PPCL supports the use of bortezomib-based therapies as frontline treatment in PPCL patients.

Preclinical Activity of JNJ-7957, a Novel BCMA×CD3 Bispecific Antibody for the Treatment of Multiple Myeloma, Is Potentiated by Daratumumab

PURPOSE

Multiple myeloma (MM) patients with disease refractory to all available drugs have a poor outcome, indicating the need for new agents with novel mechanisms of action.

EXPERIMENTAL DESIGN

We evaluated the anti-MM activity of the fully human BCMA×CD3 bispecific antibody JNJ-7957 in cell lines and bone marrow (BM) samples. The impact of several tumor- and host-related factors on sensitivity to JNJ-7957 therapy was also evaluated.

RESULTS

We show that JNJ-7957 has potent activity against 4 MM cell lines, against tumor cells in 48 of 49 BM samples obtained from MM patients, and in 5 of 6 BM samples obtained from primary plasma cell leukemia patients. JNJ-7957 activity was significantly enhanced in patients with prior daratumumab treatment, which was partially due to enhanced killing capacity of daratumumab-exposed effector cells. BCMA expression did not affect activity of JNJ-7957. High T-cell frequencies and high effector:target ratios were associated with improved JNJ-7957-mediated lysis of MM cells. The PD-1/PD-L1 axis had a modest negative impact on JNJ-7957 activity against tumor cells from daratumumab-naïve MM patients. Soluble BCMA impaired the ability of JNJ-7957 to kill MM cells, although higher concentrations were able to overcome this negative effect.

CONCLUSIONS

JNJ-7957 effectively kills MM cells ex vivo, including those from heavily pretreated MM patients, whereby several components of the immunosuppressive BM microenvironment had only modest effects on its killing capacity. Our findings support the ongoing trial with JNJ-7957 as single agent and provide the preclinical rationale for evaluating JNJ-7957 in combination with daratumumab in MM.

A case of IgE myeloma transformed into IgE-producing plasma cell leukaemia

This is a case report of a challenging diagnosis of IgE monoclonal gammopathy of undetermined significance, which transformed into myeloma, then transformed into IgE-producing plasma cell leukaemia in a 71-year-old male who was followed in Brest, France, from 2015 to 2019. The IgE-producing variant is the rarest sub-type of multiple myeloma, and plasma cell leukaemia is considered to be the rarest and the most aggressive of human monoclonal gammopathies. In November 2015, hypogammaglobulinemia was detected during a systematic check-up. A kappa light chain monoclonal gammopathy was first diagnosed due to an increase of the free kappa/lambda light chains ratio. No monoclonal immunoglobulin was detected by either serum protein electrophoresis (Capillarys 2, Sebia, Issy-les-Moulineaux, France) or immunofixation (Hydrasys 2, Sebia, Issy-les-Moulineaux, France). In June 2018, a blood smear led to the diagnosis of plasma cell leukaemia. A monoclonal peak was detected and identified as IgE-kappa. Analysis of an archival sample taken three years earlier, revealed the presence of a monoclonal IgE, which had been missed at diagnosis. Chemotherapy with bortezomib and dexamethasone was introduced. The patient survived 10 months after the diagnosis of leukaemia. This case shows that an abnormal free light chain ratio should be considered as a possible marker of IgE monoclonal gammopathy even in the absence of a solitary light chain revealed by immunofixation. In addition, the use of an undiluted serum may increase the sensitivity of the immunofixation for the detection of IgE monoclonal gammopathies compared to the 1:3 dilution recommended by the manufacturer.

Bortezomib-based Regimens Improve the Outcome of Patients with Primary or Secondary Plasma Cell Leukemia: A Retrospective Cohort Study

Objective:

The management experience for plasma cell leukemia (PCL) is still limited by PCL’s rare incidence and aggressive course. The goal of this study was to further identify the efficacy of bortezomib-containing regimens for PCL in Chinese patients.

Materials and Methods:

In this study, 56 consecutive PCL patients [14 primary PCL (pPCL) and 42 secondary PCL (sPCL) cases] were retrospectively enrolled and 42/56 patients received bortezomib-based regimens (BBRs), including 10/14 pPCL and 32/42 sPCL patients. The patients’ survival data, clinical information, and safety data were collected and analyzed.

Results:

In pPCL and sPCL patients, the overall response rate in the bortezomib group was 90.0% and 25.0%, respectively. The median progression-free survival from PCL diagnosis for pPCL and sPCL was 8.3 months vs. 2.9 months (p=0.043) and median overall survival (OS) from PCL diagnosis was 23.3 months vs. 4.0 months. The OS for patients receiving BBRs was significantly longer for both pPCL (8.3 vs. 1.2 months, p=0.002) and sPCL (4.3 vs. 1.1 months, p<0.001). In multivariate COX analysis, BBR treatment [p=0.008, hazard ratio (HR)=0.38, 95% confidence interval (CI)=0.19-0.77] and very good partial response or better (≥VGPR) (p=0.035, HR=0.19, 95% CI=0.04-0.74) were independent predictors of OS for sPCL patients. For pPCL patients, BBR predicted OS (p=0.029, HR=0.056, 95% CI=0.004-0.745) instead of ≥VGPR (p=0.272, HR=3.365, 95% CI=0.38-29.303).

Conclusion:

It was found that BBRs could significantly improve OS for both pPCL and sPCL patients.

Transcriptome analysis reveals significant differences between primary plasma cell leukemia and multiple myeloma even when sharing a similar genetic background

Primary plasma cell leukemia (pPCL) is a highly aggressive plasma cell dyscrasia characterised by short remissions and very poor survival. Although the 17p deletion is associated with poor outcome and extramedullary disease in MM, its presence does not confer the degree of aggressiveness observed in pPCL. The comprehensive exploration of isoform expression and RNA splicing events may provide novel information about biological differences between the two diseases. Transcriptomic studies were carried out in nine newly diagnosed pPCL and ten MM samples, all of which harbored the 17p deletion. Unsupervised cluster analysis clearly distinguished pPCL from MM samples. In total 3584 genes and 20033 isoforms were found to be deregulated between pPCL and MM. There were 2727 significantly deregulated isoforms of non-differentially expressed genes. Strangely enough, significant differences were observed in the expression of spliceosomal machinery components between pPCL and MM, in respect of the gene, isoform and the alternative splicing events expression. In summary, transcriptome analysis revealed significant differences in the relative abundance of isoforms between pPCL and MM, even when they both had the 17p deletion. The mRNA processing pathway including RNA splicing machinery emerged as one of the most remarkable mechanisms underlying the biological differences between the two entities.

Primary plasma cell leukemia: A case report and review of the literature

Due to the rarity and fulminant nature of the condition, there are limited data driving dialogue for optimal treatment strategies for plasma cell leukemia (PCL). Additionally, the current diagnostic definition of PCL has not been prospectively studied which may result in delays to initiating early aggressive treatment due to underdiagnosis.

High-Risk Multiple Myeloma: Integrated Clinical and Omics Approach Dissects the Neoplastic Clone and the Tumor Microenvironment

Multiple myeloma (MM) is a genetically heterogeneous disease that includes a subgroup of 10–15% of patients facing dismal survival despite the most intensive treatment. Despite improvements in biological knowledge, MM is still an incurable neoplasia, and therapeutic options able to overcome the relapsing/refractory behavior represent an unmet clinical need. The aim of this review is to provide an integrated clinical and biological overview of high-risk MM, discussing novel therapeutic perspectives, targeting the neoplastic clone and its microenvironment. The dissection of the molecular determinants of the aggressive phenotypes and drug-resistance can foster a better tailored clinical management of the high-risk profile and therapy-refractoriness. Among the current clinical difficulties in MM, patients’ management by manipulating the tumor niche represents a major challenge. The angiogenesis and the stromal infiltrate constitute pivotal mechanisms of a mutual collaboration between MM and the non-tumoral counterpart. Immuno-modulatory and anti-angiogenic therapy hold great efficacy, but variable and unpredictable responses in high-risk MM. The comprehensive understanding of the genetic heterogeneity and MM high-risk ecosystem enforce a systematic bench-to-bedside approach. Here, we provide a broad outlook of novel druggable targets. We also summarize the existing multi-omics-based risk profiling tools, in order to better select candidates for dual immune/vasculogenesis targeting.

Germline Risk Contribution to Genomic Instability in Multiple Myeloma

Genomic instability, a well-established hallmark of human cancer, is also a driving force in the natural history of multiple myeloma (MM) - a difficult to treat and in most cases fatal neoplasm of immunoglobulin producing plasma cells that reside in the hematopoietic bone marrow. Long recognized manifestations of genomic instability in myeloma at the cytogenetic level include abnormal chromosome numbers (aneuploidy) caused by trisomy of odd-numbered chromosomes; recurrent oncogene-activating chromosomal translocations that involve immunoglobulin loci; and large-scale amplifications, inversions, and insertions/deletions (indels) of genetic material. Catastrophic genetic rearrangements that either shatter and illegitimately reassemble a single chromosome (chromotripsis) or lead to disordered segmental rearrangements of multiple chromosomes (chromoplexy) also occur. Genomic instability at the nucleotide level results in base substitution mutations and small indels that affect both the coding and non-coding genome. Sometimes this generates a distinctive signature of somatic mutations that can be attributed to defects in DNA repair pathways, the DNA damage response (DDR) or aberrant activity of mutator genes including members of the APOBEC family. In addition to myeloma development and progression, genomic instability promotes acquisition of drug resistance in patients with myeloma. Here we review recent findings on the genetic predisposition to myeloma, including newly identified candidate genes suggesting linkage of germline risk and compromised genomic stability control. The role of ethnic and familial risk factors for myeloma is highlighted. We address current research gaps that concern the lack of studies on the mechanism by which germline risk alleles promote genomic instability in myeloma, including the open question whether genetic modifiers of myeloma development act in tumor cells, the tumor microenvironment (TME), or in both. We conclude with a brief proposition for future research directions, which concentrate on the biological function of myeloma risk and genetic instability alleles, the potential links between the germline genome and somatic changes in myeloma, and the need to elucidate genetic modifiers in the TME.

An update on biology, diagnosis and treatment of primary plasma cell leukemia

INTRODUCTION

Primary plasma cell leukemia (PPCL) is one of the most aggressive hematological malignancies. The prognosis of PPCL patients remains poor, although some improvements have been made in recent years. Areas covered: In this review recent clinical and biological advances in PPCL are reported. Some recommendations for the practical management of these patients are provided, with a particular focus on the role of novel agents and transplant procedures. A brief description of the currently ongoing clinical trials with new drugs is also enclosed. Expert opinion: PPCL still represents a difficult challenge for all hematologists. Here the authors provide a personal view on how the current, generally unsatisfactory results in this neoplastic disorder could be improved. In particular, dedicated studies exploring alternative therapies are necessary and eagerly awaited. Such studies should possibly be based on new biological information that could be of help in identifying novel genetic biomarkers for risk stratification and new actionable molecular targets.

The Impact of Tumor Heterogeneity on Diagnostics and Novel Therapeutic Strategies in Multiple Myeloma

Myeloma is characterized by extensive inter-patient genomic heterogeneity due to multiple different initiating events. A recent multi-region sequencing study demonstrated spatial differences, with progression events, such as TP53 mutations, frequently being restricted to focal lesions. In this review article, we describe the clinical impact of these two types of tumor heterogeneity. Target mutations are often dominant at one site but absent at other sites, which poses a significant challenge to personalized therapy in myeloma. The same holds true for high-risk subclones, which can be locally restricted, and as such not detectable at the iliac crest, which is the usual sampling site. Imaging can improve current risk classifiers and monitoring of residual disease, but does not allow for deciphering the molecular characteristics of tumor clones. In the era of novel immunotherapies, the clinical impact of heterogeneity certainly needs to be re-defined. Yet, preliminary observations indicate an ongoing impact of spatial heterogeneity on the efficacy of monoclonal antibodies. In conclusion, we recommend combining molecular tests with imaging to improve risk prediction and monitoring of residual disease. Overcoming intra-tumor heterogeneity is the prerequisite for curing myeloma. Novel immunotherapies are promising but research addressing their impact on the spatial clonal architecture is highly warranted.

Revised diagnostic criteria for plasma cell leukemia: results of a Mayo Clinic study with comparison of outcomes to multiple myeloma

The current definition of plasma cell leukemia (PCL)- ≥ 20% circulating plasma cells (CPCs) on peripheral smear and plasma cell count ≥ 2 × 10⁹/L-may be too stringent. We reviewed outcomes of 176 multiple myeloma (MM) patients diagnosed between 1971 and 2016, and who had CPCs detectable at diagnosis, to determine whether a lower threshold could be used to diagnose PCL. Median overall survival (mOS) was 1.1 years (95% CI 0.8-1.4) and was similar between patients with < 5% (n = 54, mOS = 1.4 years [0.7-2.0]), 5-19% (n = 63, mOS = 1.1 years [0.7-1.4]), and ≥ 20% CPCs (n = 59, mOS = 1.1 years [0.7-1.5], p = 0.349). As survival was similar between those with 5-19% and ≥ 20% CPCs, we stratified patients by < 5% (mOS = 1.4 years [0.7-2.0]) and ≥ 5% CPCs (mOS = 1.1 years [0.8-1.4], p = 0.154). Outcomes of those with ≥ 5% CPCs were much poorer when compared with a cohort of MM patients diagnosed between 1971 and 2016, who did not have CPCs at diagnosis (n = 9724, mOS = 4.4 yrs [4.3-4.5], p < 0.001); survival was also lower in patients diagnosed after 2001 with ≥ 5% CPCs (n = 62, mOS = 1.4 years [0.8-2.5]) compared with patients with standard risk (n = 1326, mOS = 7.5 years [7.0-8.7]) and high-risk MM (n = 381, mOS = 4.3 years [3.5-4.9], p < 0.001). We therefore propose that the definition of PCL be revised to patients with ≥ 5% CPCs on peripheral blood smear, who otherwise meet diagnostic criteria for MM.

Diffraction limited mid-infrared reflectance microspectroscopy with a supercontinuum laser

Chemical mapping was demonstrated with a mid-infrared (MIR) microspectroscopy setup based on a supercontinuum source (SC) emitting in the spectral range from 1.55 to 4.5 µm and a MEMS-based Fabry-Pérot filter spectrometer. Diffraction limited spatial resolution in reflection geometry was achieved. A multilayer film consisting of different polymers and mixtures thereof was measured and results were compared to those gained with a conventional FTIR microscope equipped with a thermal MIR source. Results show that compared to thermal sources, the application of the SC source results in higher signal-to-noise ratios together with better spatial resolution and faster scanning. Furthermore, diffraction limited imaging of red blood cells was demonstrated for the first time in the MIR spectral region in reflection mode. The distinctive characteristics of the MIR spectral region in conjunction with the high brightness, spatial coherence and broadband nature of supercontinuum radiation show the potential for improving infrared microscopy significantly.

Rare and unusual case of anti-factor XI antibodies in patient with plasma cell leukemia

Background

The acquired inhibitors of coagulation have been observed in very rare cases of monoclonal gammopathies. We report a very rare case of anti-factor XI antibodies in patient with plasma cell leukemia (PCL).

Case presentation

This is a 59-year-old male patient without pathological history, admitted to the nephrology department for management of renal insufficiency and anemia syndrome. The history and physical examination revealed stigmata of hemorrhagic syndrome including hemothorax and hemoptysis. The hemostasis assessment showed an isolated prolonged activated partial thromboplastin time (APTT) with APTT ratio = 2.0.The index of circulating anticoagulant (37.2%) revealed the presence of circulating anticoagulants. The normalized dilute Russell viper venom time ratio of 0.99 has highlighted the absence of lupus anticoagulants. The coagulation factors assay objectified the decrease of the factor XI activity corrected by the addition of the control plasma confirming the presence of anti-factor XI autoantibodies. In addition, the blood count showed bicytopenia with non-regenerative normocytic normochromic anemia and thrombocytopenia. The blood smear demonstrated a plasma cell count of 49% (2842/mm3) evoking PCL. The bone marrow was invaded up to 90% by dystrophic plasma cells. The biochemical assessment suggested downstream renal and electrolyte disturbances from exuberant light chain production with abnormalities including hyperuricemia, hypercalcemia, elevated lactate dehydrogenase, non nephrotic-range proteinuria and high level of C reactive protein. The serum protein electrophoresis showed the presence of a monoclonal peak. The serum immunofixation test detects the presence of monoclonal free lambda light chains. He was treated with velcade, thalidomide and dexamethasone. The patient died after 2 weeks despite treatment.

Conclusion

Both PCL and anti-factor XI inhibitors are two very rare entities. To the best of our knowledge, this is the first reported case of a factor XI inhibitor arising in the setting of PCL. Factor inhibitors should be suspected in patients whose monoclonal gammopathies are accompanied by bleeding manifestations.

Retrospective analysis of primary plasma cell leukemia in Kansai Myeloma Forum registry

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The prevalence of pPCL was 1.2%.

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Treatment with novel agents and transplantation may yield a better prognosis.

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Hypercalcemia at diagnosis was suggested to predict worse outcomes.

We retrospectively analyzed twenty-six patients with primary plasma cell leukemia (pPCL) registered from May 2005 until April 2015 by the Kansai Myeloma Forum. Twenty patients received novel agents (bortezomib or lenalidomide), and their median survival of was 34 months. The median survival of patients who underwent autologous stem cell transplantation (SCT) was 40 months, those undergoing allogeneic SCT 55 months, and those undergoing both types of SCT (auto–allo) 61 months; whereas for those who did not undergo SCT it was 28 months (p = 0.845). The only statistically significant risk factor identified by multivariate analysis was hypercalcemia.

Prognostic indicators in primary plasma cell leukaemia: a multicentre retrospective study of 117 patients

We report a multicentre retrospective study that analysed clinical characteristics and outcomes in 117 patients with primary plasma cell leukaemia (pPCL) treated at the participating institutions between January 2006 and December 2016. The median age at the time of pPCL diagnosis was 61 years. Ninety-eight patients were treated with novel agents, with an overall response rate of 78%. Fifty-five patients (64%) patients underwent upfront autologous stem cell transplantation (ASCT). The median follow-up time was 50 months (95% confidence interval [CI] 33; 76), with a median overall survival (OS) for the entire group of 23 months (95% CI 15; 34). The median OS time in patients who underwent upfront ASCT was 35 months (95% CI 24·3; 46) as compared to 13 months (95% CI 6·3; 35·8) in patients who did not receive ASCT (P = 0·001). Multivariate analyses identified age ≥60 years, platelet count ≤100 × 10⁹ /l and peripheral blood plasma cell count ≥20 × 10⁹ /l as independent predictors of worse survival. The median OS in patients with 0, 1 or 2-3 of these risk factors was 46, 27 and 12 months, respectively (P < 0·001). Our findings support the use of novel agents and ASCT as frontline treatment in patients with pPCL. The constructed prognostic score should be independently validated.

Leukemia with Plasma Cells — Case Report

Plasma cell leukemia (PCL) is one of the most aggressive monoclonal gammopathies, being characterized by the presence of more than 20% of plasma cells in the peripheral blood and an absolute number of these cells of more than 2×109, with different morphology, from young elements to mature cells. The incidence of PCL varies between 2–4% among multiple myeloma (MM) patients. In comparison with MM, PCL appears more often in younger patients. The following article describes the case of a 49-year-old female patient diagnosed with PCL which needed urgent control of the clinical manifestations due to its irreversible complications. Urgent autologous stem cell transplantation is recommended in this group of patients.

Carfilzomib resistance due to ABCB1/MDR1 overexpression is overcome by nelfinavir and lopinavir in multiple myeloma

Proteasome inhibitor (PI) carfilzomib (CFZ) has activity superior to bortezomib (BTZ) and is increasingly incorporated in multiple myeloma (MM) frontline therapy and relapsed settings. Most MM patients ultimately experience PI-refractory disease, an unmet medical need with poorly understood biology and dismal outcome. Pharmacologic targeting of ABCB1 improved patient outcomes, including MM, but suffered from adverse drug effects and insufficient plasma concentrations. Proteomics analysis identified ABCB1 overexpression as the most significant change in CFZ-resistant MM cells. We addressed the functional role of ABCB1 overexpression in MM and observed significantly upregulated ABCB1 in peripheral blood malignant plasma cells (PCs) vs untreated patients' bone marrow PC. ABCB1 overexpression reduces the proteasome-inhibiting activity of CFZ due to drug efflux, in contrast to BTZ. Likewise, the cytotoxicity of established anti-MM drugs was significantly reduced in ABCB1-expressing MM cells. In search for potential drugs targeting ABCB1 in clinical trials, we identified the HIV protease inhibitors nelfinavir (NFV) and lopinavir (LPV) as potent functional modulators of ABCB1-mediated drug export, most likely via modulation of mitochondria permeability transition pore. NFV and LPV restored CFZ activity at therapeutically relevant drug levels and thus represent ready-to-use drugs to be tested in clinical trials to target ABCB1 and to re-sensitize PC to established myeloma drugs, in particular CFZ.

The role of frontline autologous stem cell transplantation for primary plasma cell leukemia: a retrospective multicenter study (KMM160)

Primary plasma cell leukemia (pPCL) is a rare and aggressive plasma cell neoplasm, with rapidly progressing clinical course. We evaluated the treatment status and survival outcomes of 69 Korean patients with pPCL. Of them, 59 patients were treated; 15 (25.4%) were treated initially with novel agent-based regimens with upfront autologous stem cell transplantation (ASCT), 7 (11.9%) with conventional chemotherapy with upfront ASCT, 21 (35.6%) with novel agent-based regimens only, and 16 (27.1%) were treated with conventional chemotherapy alone. Overall response rates after initial therapy were significantly higher in patients treated with novel agent-based regimens compared with those treated with conventional chemotherapies (75% vs. 43.4%, P = 0.026). Median progression-free survival (PFS) and overall survival (OS) were 12.2 months and 16.1 months, respectively. The median PFS of the four treatment groups–conventional chemotherapy alone, novel agents alone, conventional chemotherapy with ASCT, and novel agents with ASCT–were 1.2, 9.0, 10.5, and 26.4 months, respectively (P < 0.001); the median OS of the four treatment groups were 2.9, 12.3, 14.1, and 31.1 months, respectively (P < 0.001). The median OS was also significantly better in the patients with novel agents with ASCT versus other patients. In a multivariate analysis, an increased lactate dehydrogenase level, low albumin (< 3.5 g/dL), and non-CR after front-line treatment were independently associated with poor PFS and OS. In conclusion, the use of novel agent-based therapy with ASCT and achieving a deep response to front-line treatment are important in expecting improved PFS and OS in patients with pPCL.

Serial measurements of circulating plasma cells before and after induction therapy have an independent prognostic impact in patients with multiple myeloma undergoing upfront autologous transplantation

Circulating plasma cells at diagnosis, prior to auto-transplant and at relapse have a negative impact on survival in multiple myeloma. However, the impact of kinetics of circulating plasma cells along the course of illness has not been defined. We have analyzed 247 newly diagnosed multiple myeloma patients undergoing early auto-transplant who had paired evaluation of circulating plasma cells at diagnosis and pre-transplant by 6-color flow cytometry. A total of 117 patients had no detectable circulating plasma cells at both time points (CPC−/−), 82 had circulating plasma cells at diagnosis followed by complete eradication after induction (CPC+/−) and 48 had circulating plasma cells at transplant, including persistence of cells (CPC+/+; n=45) or emergence of new cells (CPC−/+; n=3) after induction. The rate of post-transplant stringent complete response was 32% in the CPC−/−, 30% in CPC+/− and 12% in CPC+/+ or −/+ groups (P=0.018). At a median follow up of 58 months from transplantation, the median progression-free survival in the 3 respective groups were 30, 24 and 14 months, and the 5-year overall survival rates were 83%, 70% and 43% (P<0.001 for both comparisons). On a multivariate analysis for overall survival, the risk of mortality was higher in CPC +/− (hazard ratio 2.7, 95%CI: 1.3–5.8; P=0.009) and CPC+/+ or −/+ (hazard ratio 5.7, 95%CI: 2.5–13.1; P<0.001) groups compared to the CPC−/− group. Monitoring for circulating plasma cells before induction therapy and before transplant by 6-color flow cytometry is predictive of survival in newly diagnosed myeloma and should be incorporated into clinical trials.

Prognostic impact of circulating plasma cells in patients with multiple myeloma: implications for plasma cell leukemia definition

The presence of circulating plasma cells in patients with multiple myeloma is considered a marker for highly proliferative disease. In the study herein, the impact of circulating plasma cells assessed by cytology on survival of patients with multiple myeloma was analyzed. Wright-Giemsa stained peripheral blood smears of 482 patients with newly diagnosed myeloma or plasma cell leukemia were reviewed and patients were classified into 4 categories according to the percentage of circulating plasma cells: 0%, 1–4%, 5–20%, and plasma cell leukemia with the following frequencies: 382 (79.2%), 83 (17.2%), 12 (2.5%) and 5 (1.0%), respectively. Median overall survival according to the circulating plasma cells group was 47, 50, 6 and 14 months, respectively. At multivariate analysis, the presence of 5 to 20% circulating plasma cells was associated with a worse overall survival (relative risk 4.9, 95% CI 2.6–9.3) independently of age, creatinine, the Durie-Salmon system stage and the International Staging System (ISS) stage. Patients with ≥5% circulating plasma cells had lower platelet counts (median 86×10⁹/L vs. 214×10⁹/L, P<0.0001) and higher bone marrow plasma cells (median 53% vs. 36%, P=0.004). The presence of ≥5% circulating plasma cells in patients with multiple myeloma has a similar adverse prognostic impact as plasma cell leukemia.