Delayed stem cell transplantation for the management of relapsed or refractory multiple myeloma

The changing landscape of relapsed and/or refractory multiple myeloma (MM): fundamentals and controversies

The increase in the number of therapeutic alternatives for both newly diagnosed and relapsed/refractory multiple myeloma (RRMM) patients has widened the clinical scenario, leading to a level of complexity that no algorithm has been able to cover up to date. At present, this complexity increases due to the wide variety of clinical situations found in MM patients before they reach the status of relapsed/refractory disease. These different backgrounds may include primary refractoriness, early relapse after completion of first-line therapy with latest-generation agents, or very late relapse after chemotherapy or autologous transplantation. It is also important to bear in mind that many patient profiles are not fully represented in the main randomized clinical trials (RCT), and this further complicates treatment decision-making. In RRMM patients, the choice of previously unused drugs and the number and duration of previous therapeutic regimens until progression has a greater impact on treatment efficacy than the adverse biological characteristics of MM itself. In addition to proteasome inhibitors, immunomodulatory drugs, anti-CD38 antibodies and corticosteroids, a new generation of drugs such as XPO inhibitors, BCL-2 inhibitors, new alkylators and, above all, immunotherapy based on conjugated anti-BCMA antibodies and CAR-T cells, have been developed to fight RRMM. This comprehensive review addresses the fundamentals and controversies regarding RRMM, and discusses the main aspects of management and treatment. The basis for the clinical management of RRMM (complexity of clinical scenarios, key factors to consider before choosing an appropriate treatment, or when to treat), the arsenal of new drugs with no cross resistance with previously administered standard first line regimens (main phase 3 clinical trials), the future outlook including the usefulness of abandoned resources, together with the controversies surrounding the clinical management of RRMM patients will be reviewed in detail.

Therapy for Relapsed Multiple Myeloma: Guidelines From the Mayo Stratification for Myeloma and Risk-Adapted Therapy

Life expectancy in patients with multiple myeloma is increasing because of the availability of an increasing number of novel agents with various mechanisms of action against the disease. However, the disease remains incurable in most patients because of the emergence of resistant clones, leading to repeated relapses of the disease. In 2015, 5 novel agents were approved for therapy for relapsed multiple myeloma. This surfeit of novel agents renders management of relapsed multiple myeloma more complex because of the occurrence of multiple relapses, the risk of cumulative and emergent toxicity from previous therapies, as well as evolution of the disease during therapy. A group of physicians at Mayo Clinic with expertise in the care of patients with multiple myeloma regularly evaluates the evolving literature on the biology and therapy for multiple myeloma and issues guidelines on the optimal care of patients with this disease. In this article, the latest recommendations on the diagnostic evaluation of relapsed multiple myeloma and decision trees on how to treat patients at various stages of their relapse (off study) are provided together with the evidence to support them.

First line vs delayed transplantation in myeloma: Certainties and controversies

Since the middle of 1990s autologous stem cell transplantation has been the cornerstone for the treatment of young patients with multiple myeloma (MM). In the last decade the introduction of novel agents such as immunomodulatory drugs (IMiDs) and proteasome inhibitors (PI), has dramatically changed the therapeutic scenario of this yet incurable disease. Due to the impressive results achieved with IMiDs and PI both in terms of response rates and in terms of progression free and overall survival, and to the toxicity linked to high dose therapy and autologous stem cell transplantation (ASCT), a burning question nowadays is whether all young patients should be offered autotransplantation up front or if this should be reserved for the time of relapse. This article provides a review of the data available regarding ASCT in MM and of the current opinion of the scientific community regarding its optimal timing.

Treatment strategies in relapsed and refractory multiple myeloma: a focus on drug sequencing and 'retreatment' approaches in the era of novel agents

Treatment of multiple myeloma has evolved over the last decade, most notably with the introduction of highly effective novel agents. It is now possible to aim for deep disease responses in a greater number of patients in an attempt to prolong remission duration and survival. Initially introduced in the relapsed setting, the novel agents, namely thalidomide, bortezomib and lenalidomide, are now being increasingly incorporated into upfront treatment strategies, raising questions about the feasibility of 'retreatment' with such agents. Also, in a disease that is characterized by multiple relapses, the 'sequencing' of the different effective options is an important question. In the frontline setting, the first remission is likely to be the period during which patients will enjoy the best quality of life. Thus, the goal should be to achieve a first remission that is the longest possible by using the most effective treatment upfront. At relapse, the challenge is to select the optimal treatment for each patient while balancing efficacy and toxicity. The decision will depend on both disease- and patient-related factors. This review aimed to assess the available research data addressing 'retreatment' approaches, drug 'sequencing' and the long-term impact of upfront therapy with novel drugs.

Current trends in autologous stem-cell transplantation for myeloma in the era of novel therapies

Since the mid 1990s, high-dose therapy followed by autologous stem-cell transplantation (ASCT) has been considered the standard of care for frontline therapy in younger patients with multiple myeloma (MM). During the past 10 years, thalidomide, bortezomib, and lenalidomide have been widely incorporated to the therapeutic armamentarium for the treatment of this disease. These agents show promise for improving the rate of complete remission both before and after ASCT without increasing toxicity. However, it is not clear whether such therapies are superior if they are used as an alternative to transplantation or whether they may reduce the need for and use of transplantation in patients in whom treatment is indicated. Therefore, the role of ASCT itself is a matter of debate: Should it be used upfront or as salvage treatment at the time of progression in patients initially treated with novel agents? This review presents current trends in ASCT for MM in the era of novel therapies.

Treatment of relapsed and refractory multiple myeloma in the era of novel agents

The introduction of the Immunomodulatory drugs (IMiDs) and proteasome inhibitors, used either as a single-agent or combined with classic anti-myeloma therapies, has improved the outcome for patients with relapsed myeloma. However, there is currently no generally accepted standard treatment for relapsed/refractory myeloma patients, partly because of the absence of trials comparing the efficacy of the novel agents in relapsed/refractory myeloma. Choice of a new treatment regimen depends on both patient and disease-specific characteristics. A lenalidomide-based regimen is the first choice in patients with neuropathy, while bortezomib has the highest efficacy in patients with renal insufficiency and is not associated with increased risk of thromboembolism. A second autologous stem cell transplantation (auto-SCT) can be applied in patients with a progression-free period of ≥ 18-24 months after the first auto-SCT. In high-risk relapse such as occurring early after auto-SCT consolidation with allogeneic SCT can be considered. In this review we provide an overview of the various salvage regimens and give recommendations for treatment of patients with relapsed/refractory myeloma in different clinical settings.

A Phase II study of (153)Sm-EDTMP and high-dose melphalan as a peripheral blood stem cell conditioning regimen in patients with multiple myeloma

Multiple myeloma (MM) remains an incurable illness affecting nearly 20,000 individuals in the United States per year. High-dose melphalan (HDM) with autologous hematopoietic stem cell support (ASCT) is one of the mainstays of therapy for younger patients, but little advancement has been made with regards to conditioning regimens. We opted to combine (153)Samarium ethylenediaminetetramethylenephosphonate ((153)Sm-EDTMP), a radiopharmaceutical approved for the palliation of pain caused by metastatic bone lesions, with HDM and ASCT in a Phase II study. Individualized doses of (153)Sm were based on dosimetry and were calculated to deliver 40 Gy to the bone marrow. The therapeutic dose of (153)Sm-EDTMP was followed by HDM and ASCT. Forty-six patients with newly diagnosed or relapsed disease were treated. Study patients were compared to 102 patients contemporaneously treated with HDM and ASCT. Fifty-nine percent of study patients achieved a very good partial response (VGPR) or better. With a median follow-up of 7.1 years, the median overall survival and progression free survival (PFS) from study registration was 6.2 years (95% CI 4.6-7.5 years) and 1.5 years (1.1-2.2 years), respectively, which compared favorably to contemporaneously treated non-study patients. Addition of high-dose (153)Sm-EDTMP to melphalan conditioning appears to be safe, well tolerated, and worthy of further study in the context of novel agents and in the Phase III setting.

Relevant prognostic features of multiple myeloma and the new International Staging System

The new International Staging System should be reported in all future studies of multiple myeloma. However, the system fails to account for recent research findings pertaining to mechanisms of disease progression. This review describes development of the International Staging System and details prognostic factors that may further our understanding of the biology of multiple myeloma.

Single autologous stem-cell transplantation followed by maintenance therapy with thalidomide is superior to double autologous transplantation in multiple myeloma: results of a multicenter randomized clinical trial

From April 2003 to December 2006, 195 patients with de novo symptomatic myeloma and younger than 60 years of age were randomly assigned to receive either tandem transplantation up front (arm A, n = 97) or one autologous stem-cell transplantation followed by a maintenance therapy with thalidomide (day + 90, 100 mg per day during 6 months) (arm B, n = 98). Patients included in arm B received a second transplant at disease progression. In both arms, autologous stem-cell transplantation was preceded by first-line therapy with thalidomide-dexamethasone and subsequent collection of peripheral blood stem cells with high-dose cyclophosphamide (4 g/m(2)) and granulocyte colony stimulating factor. Data were analyzed on an intent-to-treat basis. With a median follow-up of 33 months (range, 6-46 months), the 3-year overall survival was 65% in arm A and 85% in arm B (P = .04). The 3-year progression-free survival was 57% in arm A and 85% in arm B (P = .02). Up-front single autologous transplantation followed by 6 months of maintenance therapy with thalidomide (with second transplant in reserve for relapse or progression) is an effective therapeutic strategy to treat multiple myeloma patients and appears superior to tandem transplant in this setting. This study was registered at www.ClinicalTrials.gov as (NCT 00207805).

Serum M-spike and transplant outcome in patients with multiple myeloma

High dose therapy with autologous stem cell transplantation (HDT-ASCT) has prolonged survival in patients with multiple myeloma. Patients who achieve a complete response (CR) benefit the most from this form of therapy. Thus, achieving a CR is an important goal of therapy and it will be beneficial if the probability of achieving CR can be determined for any patient before transplant. Here we report that pretransplant monoclonal protein level (M-spike) was found to be an important predictor. Thus, we used knowledge of the rate of M-protein production by myeloma cells together with the clearance of the protein to estimate the pretransplant disease burden. We show that the pretransplant disease burden, based on the M-spike, is the only predictor for achieving CR. A simple function that describes this probability is presented. We also provide an estimate of the rate of tumor regrowth in patients who obtain a CR and in patients who only get a partial response with HDT-ASCT. The significant expansion of myeloma cells after HDT-ASCT is clearly evident. Clinical trials must be designed that take into account these kinetic aspects of the disease.

In vivo and in silico studies on single versus multiple transplants for multiple myeloma

High-dose therapy and autologous stem cell transplantation (HDT-ASCT) have significantly improved survival in multiple myeloma (MM). However, patients are not cured, responses are variable and only about 40% of patients achieve a complete response (CR). Optimal timing of the procedure and knowledge of the relapse kinetics may assist physicians when they consider this therapeutic modality for their patients. We analyzed myeloma tumor burden and kinetics before and after HDT-ASCT in a cohort of 265 patients. Disease burden was estimated from serial M-spike measurements and the data fitted to the Gompertz function to determine the general parameters for all patients. Functions that couple disease burden and kinetics with time to progression (TTP) were derived and used to determine the optimal timing of transplantation. Patients who achieve CR with the first episode of HDT-ASCT should not be routinely offered tandem transplantation but carefully monitored and transplanted at an optimal disease burden. If CR is not achieved with a first trial of HDT-ASCT, the probability of CR after a tandem second trial is approximately 10%. TTP after tandem transplants (with its higher associated mortality) cannot be superior to TTP achieved with optimally timed serial transplants. Individualized HDT-ASCT for patients with MM is possible and may optimize results.

Prolonged overall survival with second on-demand autologous transplant in multiple myeloma

Between August 1993 and March 2003, 130 consecutive multiple myeloma (MM) patients eligible for high-dose treatment were offered a program including up-front autologous stem cell transplantation (ASCT) after conditioning with 200 mg/m(2) melphalan followed by a second ASCT in case of relapse or progression. A total of 107 (82%) patients completed the first ASCT. The best response obtained after ASCT was complete response (CR) 23%, very good partial response (VGPR) 28%, partial response (PR) 42%, and minimal response (MR) 7%. Median overall survival (OS) and event-free survival (EFS) were 65.4 and 27.7 months, respectively. Relapse or progression occurred in 70 patients; 26 received a second ASCT (with a median time of 20.4 months from first ASCT). A major response (> or =PR) was obtained in 69% of these patients. Median OS and EFS after the second ASCT were 38.1 and 14.8 months. Treatment-related mortality was 1.9% after the first ASCT but no deaths occurred after the second. Our experience suggests that elective up-front single ASCT followed by second ASCT after relapse or progression is a safe and effective global strategy to treat MM patients.

Flow cytometric detection of circulating myeloma cells before transplantation in patients with multiple myeloma: a simple risk stratification system

Detection of circulating myeloma cells (CMCs) by flow cytometry in patients with multiple myeloma (MM) indicates active disease. We hypothesized that detection of CMCs at the time of stem-cell collection prior to autologous stem-cell transplantation (ASCT) identifies patients at high risk of rapid progression. A cohort of patients undergoing ASCT was identified. CMCs were determined by gating on CD38+/CD45- cells using flow cytometry. The impact of CMCs on overall survival (OS) and time to progression (TTP) was evaluated in univariate and multivariate analyses. Of 246 patients undergoing ASCT, 95 had CMCs. Complete response (CR) rates after transplantation were 32% and 36% for patients with and without CMCs, respectively (P = .50). OSs were 33.2 and 58.6 months (P = .01) whereas TTPs were 14.1 and 22 months, respectively (P = .001). On multivariate analysis, CMCs remained independent of cytogenetics and disease status at time of transplantation (P = .03). CMCs and cytogenetics were combined in a new scoring system. Patients with neither, one, or both parameters had a median OS of 55, 48, and 21.5 months and a median TTP of 22, 15.4, and 6.5 months, respectively. CMCs at the time of ASCT is an independent prognostic factor and in combination with cytogenetics provides a powerful scoring system that stratifies patients and guides management.

Bortezomib, a novel proteasome inhibitor, in the treatment of hematologic malignancies

Proteasome inhibition is a novel approach to treating malignancy, and bortezomib is the first proteasome inhibitor in this class to be approved for clinical use. In preclinical studies, bortezomib caused cell cycle arrest and apoptosis in myeloma and lymphoma cell lines as well as in other neoplastic cell types. Phase I clinical trials established an optimal dosing strategy and demonstrated a manageable toxicity profile. Cyclical thrombocytopenia and peripheral neuropathy, which generally abate after cessation of treatment, are the most clinically significant toxicities. Two phase II trials, SUMMIT and CREST, demonstrated impressive activity with bortezomib 1.3 mg/m2 monotherapy in relapsed and refractory myeloma, with an impressive 35% response rate (complete+partial+minimal responses) in SUMMIT and a 50% response rate in CREST, using the rigorous European Group for Blood and Marrow Transplantation criteria. A recently completed phase III trial showed the significant clinical benefits of bortezomib over high-dose dexamethasone in patients with relapsed myeloma. Results of ongoing trials with bortezomib in the first-line treatment of myeloma have been extremely encouraging and have demonstrated the benefit of using bortezomib as part of an induction regimen prior to stem cell transplantation. Importantly, two clinical trials with bortezomib as monotherapy in refractory non-Hodgkin's lymphoma have shown impressive response rates, particularly in aggressive mantle cell lymphoma.

Current status of stem cell transplantation for multiple myeloma

Stem cell transplantation for myeloma has become a standard of care for newly diagnosed patients. Current evidence favors tandem transplants for those patients not achieving a complete or very good partial response (<90%) after the first transplant. Transplantation is safe and has been shown to prolong survival even in patients 65 to 70 years of age. Whether the new agents thalidomide, lenalidomide, and bortezomib will have an impact on the survival advantage of stem cell transplantation is unknown.

Hematopoietic stem cell mobilization with intravenous melphalan and G-CSF in patients with chemoresponsive multiple myeloma: report of a phase II trial

Multiple myeloma (MM) is an incurable hematologic malignancy for which autologous hematopoietic stem cell transplantation (HCT) is a standard therapy. The optimal method of stem cell mobilization is not defined. We evaluated intravenous melphalan (60 mg/m2), the most effective agent for MM, and G-CSF (10 microg/kg/day) for mobilization. End points were safety, adequacy of CD34+ collections, MM response, and contamination of stem cell components (SCC). In total, 32 patients were mobilized. There were no deaths or significant bleeding episodes; 14 patients (44%) required hospitalization for neutropenic fever. Median days of grade 3 or 4 neutropenia or thrombocytopenia were 7 (2-20) and 8 (3-17). Median mobilization days, CD34+ cells/kg and total leukaphereses were 16 (12-30), 12.1 million (2.6-52.8), and 2 (1-5) respectively. Four patients (12.5 %) failed to achieve the target of 4 million CD34+ cells/kg in five leukaphereses. Reduction in myeloma was seen in 11 patients (34%) with 3 (9%) achieving complete response; 15 (47%) maintained prior responses. Estimated MM contamination per SCC (N=48) was 0.0009% (range 0-0.1) and 0.21 x 10(4) cells per kg (range 0-41.2). Increased contamination was associated with increased patient age. This strategy for mobilization is feasible, frequently requires hospitalization and transfusion, and controls disease in most patients.

Etoposide, methylprednisolone, cytarabine and cisplatin successfully cytoreduces resistant myeloma patients and mobilizes them for transplant without adverse effects

Myeloma remains incurable with a median survival of 4 years, but outcome can be improved by the use of high-dose therapy. We used the etoposide, methylprednisolone, cytarabine and cisplatin (ESHAP) regimen as second-line therapy in 42 newly diagnosed myeloma patients who had failed vincristine, adriamycin and dexamethasone (VAD)- type therapy (n = 36), responded to first-line treatment but persisted in having significant residual marrow plasmacytosis (n = 5) or failed prior stem cell harvesting (n = 1), with the dual aim of improving disease response and mobilizing peripheral blood stem cells. Fourteen of 21 (67%) patients with no change or progressive disease after VAD responded to ESHAP; seven of 12 (58%) patients with minor response converted to partial response. Marrow plasmacytosis fell from a median of 52% at diagnosis to 23.5% after primary therapy and to15% after ESHAP. ESHAP chemotherapy was well-tolerated. There were 11 admissions due to febrile neutropenia (n = 7), nausea and vomiting (n = 2), pneumonia (n = 1) and perforated bowel (n = 1). Renal function deteriorated in 13 of 42 patients after ESHAP, but none required renal support. ESHAP mobilization was performed in 32 patients of whom 87% achieved a CD34(+) yield >2 x 10(6)/kg. In all, 38 patients proceeded to high-dose therapy. The overall survival for all patients was 62% at 4 years following ESHAP. We conclude that ESHAP has acceptable toxicity and efficient stem cell mobilizing capability, effectively cytoreduced this chemoresistant group of patients, and did not appear to adversely affect transplant outcome.

Benefit and Timing of Second Transplantations in Multiple Myeloma: Clinical Findings and Methodological Limitations in a European Group for Blood and Marrow Transplantation Registry Study

Purpose

To use European Group for Blood and Marrow Transplantation registry data to assess the benefit and optimal timing of a double-autologous transplantation strategy for patients with myeloma.

Patients and Methods

7,452 transplantation patients described as being either in a multiple graft program (“planned”) or not, were analyzed on an intention-to-treat basis. Subsequent multivariate analyses concentrated on the real occurrence of second transplantation, survival, relapse, and transplant-related mortality.

Results

Although the transplantation rate in the planned group failed to reach 60%, the median survival from transplantation is 60 months for the planned, compared with 51 months for the remainder group. While the hazard ratio of the planned group is 0.89 (95% CI, 0.79 to 1.00; P =.05) before approximately 70 months, this “effect” is reversed after 70 months, with the hazard ratio estimated as 3.01 (95% CI, 1.07 to 8.46; P = .04). A time-dependent multivariate Cox analysis shows that, taking patients without a second transplantation as a reference group, those receiving a second transplantation in first remission (ie, before relapse) show an increased probability of transplant-related mortality, especially if the transplantation is performed more than 12 months after the first, and the reduction of the risk of relapse is less than when the transplantation is performed earlier. Performing a second transplantation after relapse does not seem to prolong survival, though a second transplantation before relapse is associated with a higher probability of mortality.

Conclusion

To improve survival of tandem autologous transplantation in multiple myeloma, the second transplantation should preferably be performed before relapse and within 6 to 12 months of the first transplantation.

DTPACE: an effective, novel combination chemotherapy with thalidomide for previously treated patients with myeloma

PURPOSE

To improve outcome in previously treated patients (at least two cycles of standard therapy) with multiple myeloma, thalidomide was combined with cytotoxic chemotherapy as induction therapy.

PATIENTS AND METHODS

The regimen consisted of 4-days of oral dexamethasone, daily thalidomide, and 4 days of continuous-infusion cisplatin, doxorubicin, cyclophosphamide, and etoposide (DTPACE). Response to two cycles of DTPACE for induction was evaluated in 236 patients. Before being treated with DTPACE, 148 patients (63%) had shown progressive disease while receiving standard chemotherapy, and 55 patients (23%) had chromosome 13 abnormalities.

RESULTS

The partial remission rate (PR) after two cycles of DTPACE was 32%, with 16% attaining a complete remission (CR) or near-CR (nCR; defined as only immunofixation electrophoresis-positive). Patients with high lactate dehydrogenase (LDH; n = 98) showed a better response than those with normal LDH (n = 138): PR or better, 43% v 27% (P =.01); CR + nCR, 25% v 11% (P =.01). Patients with chromosome 13 abnormalities (n = 55) responded equally well as the other patients (n = 181): PR or better, 35% v 33% (P =.84); CR + nCR, 17% v 15% (P =.73). Patients who received 100% dose of DTPACE for two cycles (n = 115) achieved higher response rates than those with less than 100% dose (n = 121): PR or better, 49% v 17% (P <.0001); CR + nCR, 27% v 6% (P <.0001).

CONCLUSION

Combination therapy of oral dexamethasone and thalidomide with infusional chemotherapy is effective as induction therapy before autotransplantation, especially in patients with high-risk features.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of multiple myeloma: an evidence-based review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of multiple myeloma (MM) is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published medical literature and for grading the quality of the evidence, the strength of the evidence, and the strength of the treatment recommendations. Treatment recommendations based on the evidence presented in the review were made unanimously by a panel of MM experts. Recommendations for SCT as an effective therapy for MM include the following: SCT is preferred to standard chemotherapy as de novo therapy; SCT is preferred as de novo rather than salvage therapy; autologous peripheral blood stem cell transplantation (PBSCT) is preferred to bone marrow transplantation (BMT); and melphalan is preferred to melphalan plus total body irradiation as the conditioning regimen for autologous SCT. Recommendations that SCT is not effective include the following: current purging techniques of bone marrow. Recommendations of equivalence include the following: PBSCT using CD34+ selected or unselected stem cells. No recommendation is made for indications or transplantation techniques that have not been adequately studied, including the following: SCT versus standard chemotherapy as salvage therapy, tandem autologous SCT, autologous or allogeneic SCT as a high-dose sequential regimen, allogeneic BMT versus PBSCT, a preferred allogeneic myeloablative or non-myeloablative conditioning regimen, and maintenance therapy post-autologous SCT with interferon alpha post-SCT. The priority area of needed future research is maintenance therapy posttransplantation with nothing versus interferon alpha versus other agents such as corticosteroids or thalidomide or its derivatives.

Controversy in multiple myeloma transplants: tandem autotransplants and mini-allografts

Autologous stem cell transplantation appears to enhance outcome in multiple myeloma patients. To improve upon these results, various groups have utilized tandem autografts, as well as used reduced-conditioning allogeneic stem cell transplantation. These two approaches, discussed herein, have been promising. Inherent patient selection, however, appears to play a role and much of the data have not yet been subjected to peer-review scrutiny. At present, these strategies remain investigational and cannot be considered the standard-of-care for multiple myeloma patients.

A therapeutic strategy for isolated plasmacytoma of bone

Two cases of solitary plasmacytoma of bone (SPB) were diagnosed. The first case was a 41-year-old woman, complaining of fatigue from her lumbar region to her legs. The second case was a 56-year-old man complaining of poor gait and severe lumbago with numbness in the toes of both feet. Magnetic resonance imaging showed the osteolytic lesion in the 12th thoracic bone in the first patient and around the 2nd, 3rd and 4th lumbar bones in the second patient. In both patients serum analysis revealed the monoclonal component of immunoglobulin G (IgG) protein with kappa-light chain, and considering this and other findings SPB was diagnosed. Both patients were first treated with irradiation around the involved bone and then with a course of chemotherapy. In the first patient the tumour region of the bone was surgically removed and replaced with a ceramic spacer. The symptoms of both patients were ameliorated, and the patients remained in good condition for around 3 years without conversion to multiple myeloma. In view of the overall effectiveness of treatments for SPB, our therapeutic strategy deserves careful evaluation.

Plasma cell leukemia

Plasma cell leukemia (PCL) is a rare aggressive variant of multiple myeloma (MM) characterized by a fulminant course and poor prognosis. The median survival is measured in months. Therapy and prognosis partially depend on whether the disease presents de novo or as a secondary process involving the leukemic transformation of a previously diagnosed MM. Secondary PCL represents a terminal event for refractory/relapsed MM and is usually not responsive to any treatment modality. The optimal regimens for the treatment of primary PCL have not been firmly established. Induction with combination chemotherapy, followed by high-dose chemotherapy (preferably within the setting of a clinical trial), is the current recommended approach for eligible patients.