Allogeneic transplantation of unmanipulated peripheral blood stem cells in patients with multiple myeloma

Role of Stem Cell Transplantation in Multiple Myeloma

Autologous stem cell transplantation (auto-SCT) has been the standard of care in eligible newly diagnosed multiple myeloma (MM) patients. Outcomes of patients with MM have improved significantly due to the advent of several novel drugs. Upfront use of these drugs in induction therapy has significantly increased the rate and depth of responses that have translated into longer remission and survival. This has now raised a debate regarding the role and relevance of auto-SCT in the management of myeloma. However, clinical trials have confirmed the utility of auto-SCT even in the era of novel drugs. Tandem auto-SCT followed by maintenance has shown a progression-free survival (PFS) benefit in high-risk MM, and hence can be considered in young and fit patients with high-risk disease. Auto-SCT has the advantages of resetting the bone marrow microenvironment, short-lived toxicity compared to the long-term physical and financial toxicities of continued chemotherapy in the absence of SCT, very low transplant-related mortality (TRM) in high volume centers, and providing longer disease-free survival when followed by maintenance therapy. Allogeneic SCT is one potentially curative option for MM, albeit with an increased risk of death due to high TRM. Strategies to modulate the graft-versus-host disease (GVHD) while maintaining or improving the graft-versus-myeloma (GVM) effect could place allogeneic SCT back in the treatment armamentarium of MM.

Unrelated stem cell transplantation for patients with multiple myeloma

PURPOSE OF REVIEW

The role of allogeneic stem cell transplantation (SCT) in treatment of myeloma patients is still controversial. Meanwhile, the numbers of unrelated SCT for hematological diseases in Europe are higher than for human leukocyte antigen (HLA)-identical sibling transplantations, but in multiple myeloma only 39% of the allogeneic transplantations are performed from unrelated donors and only a minority were done within prospective clinical trials.

RECENT FINDINGS

The few published data of unrelated SCT in multiple myeloma reported a higher treatment-related mortality for standard myeloablative conditioning in comparison to reduced-intensity conditioning. Despite the heterogeneous patient selection in the trial, lower nonrelapse mortality and improved survival can be achieved by careful donor selection (10/10 HLA-alleles, male donor). Natural killer-alloreactivity might play a role, but conclusive data are lacking. Transplantation in more advanced or refractory patients is associated with an inferior outcome. The results of an unrelated SCT seem to be comparable to those of HLA-identical siblings, but a direct comparison is lacking so far.

SUMMARY

Unrelated SCT in multiple myeloma is feasible, but prospective clinical trials using unrelated stem cell donors are urgently needed to define the role of an unrelated SCT in multiple myeloma in the era of novel agents.

Long-term follow-up of an intensified myeloablative conditioning regimen with in vivo T cell depletion followed by allografting in patients with advanced multiple myeloma

We report long-term results after a median follow-up of 105 months in 18 patients with multiple myeloma who received an intensified myeloablative conditioning regimen regimen consisting of modified total body irradiation, busulfan, cyclophosphamide, and antithymocyte globulin, followed by allogeneic stem cell transplantation (SCT). Grade II-IV acute graft-versus-host disease occurred in 7 patients (44%), and treatment-related mortality was 17%. Complete remission (CR) with negative immunofixation after allogeneic SCT occurred in 53% of the patients. For all patients, the estimated overall survival at 12 years was 50% (95% confidence interval [CI], 26%-74%), and the estimated event-free survival (EFS) was 35% (95% CI, 23%-57%). Those patients who achieved CR after SCT had a 12-year estimated PFS of 60%, whereas none of the patients without CR remained progression-free. Our data indicate that an intensified myeloablative conditioning regimen followed by allogeneic SCT can produce long-term survival and freedom from disease in patients with multiple myeloma who achieve CR.

Is there still a role for allogeneic stem-cell transplantation in multiple myeloma?

Despite significant improvements in survival for multiple myeloma patients through autologous stem-cell transplantation (SCT) and the introduction of novel drugs, the disease remains incurable for all but a small fraction of patients. Only allogeneic SCT is potentially curative, due in part to a graft-versus-myeloma effect. High transplant-related mortality with allogeneic SCT is currently the major limitation to wider use of this potentially curative modality. Mortality can be reduced through the use of lower-intensity conditioning regimens which allow engraftment of allogeneic stem cells, but this comes at a cost of higher rates of disease progression and relapse. Promising studies to improve outcomes of allogeneic transplants include the use of more intensive non-myeloablative conditioning regimens, tandem transplants, peripheral blood cells, graft engineering to improve the graft-versus-myeloma activity while reducing graft-versus-host disease (GVHD), post-transplant maintenance, and targeted conditioning therapies such as bone-seeking radioisotopes.

Hematopoietic Stem Cell Transplantation in Multiple Myeloma

High-dose therapy and autologous hematopoietic stem cell transplantation are standard early treatment of patients with multiple myeloma. Tandem transplantation appears to provide additional benefit, particularly in patients with limited response to initial transplantation. Myeloablative allogeneic transplantation provides the only potential for cure, but has been largely abandoned because of high mortality rates. Newer and better induction regimens, rigorous analysis of results with autologous and allogeneic transplantation, and the development of risk-adapted stratification provide the impetus for this critical evaluation of the role of hematopoietic stem cell transplantation in multiple myeloma.

Mini-Midi-Maxi? How to harness the graft-versus-myeloma effect and target molecular remission after allogeneic stem cell transplantation

Allogeneic stem cell transplantation in multiple myeloma after standard myeloablative conditioning induces a high rate of complete remissions, but long-term freedom from disease is achieved in 30-40% of the cases only. The therapeutic effect of allogeneic stem cell transplantation is due to cytotoxicity of high-dose chemotherapy and immune-mediated graft-versus-myeloma effect by donor T cells. Retrospective studies clearly suggest that both (a) reducing the intensity of high-dose chemotherapy by using reduced-intensity or non-myeloablative conditioning regimen or (b) reducing the immunotherapy of donor T cells by using T-cell depletion result in lower treatment-related morbidity and mortality, but also in higher rate of relapse. Therefore, this review will focus on potential strategies of how treatment-related morbidity and mortality might be kept low without an increased risk of relapse and how remission status after transplantation can be enhanced by using the newly established donor immunosystems after allografting as a platform for post-transplant treatment strategies with new drugs (thalidomide, lenalidomide, bortezomib) or immunotherapy (donor lymphocyte infusion, vaccination, tumor-specific T cells) in order to achieve remission on a molecular level, which seems to be a 'conditio sine qua non' to cure myeloma patients.

The current status of reduced-intensity allogeneic hematopoietic stem cell transplantation for multiple myeloma

Of all the treatment modalities employed to control multiple myeloma, only allogeneic hematopoietic stem cell transplantation is potentially curative, due in large part to a graft-versus-myeloma (GVM) effect. Whereas patients who receive either allogeneic or autologous stem cell transplants for multiple myeloma have similar 3-5-year survival, only allograft recipients appear to enjoy long-term disease-free survival. High transplant-related mortality (TRM) associated with allogeneic stem cell transplantation is currently the major limitation to wider use of this potentially curative modality. This high mortality has been the major impetus for exploration of reduced intensity conditioning (RIC) regimens designed to allow engraftment of allogeneic stem cells. With follow-up now extending to 7 years, it is clear that when compared to myeloablative transplants, RIC allografts are associated with lower TRM; however, reduced mortality comes at a cost of higher rates of disease progression and relapse. Strategies designed to improve the therapeutic index of allografts include the use of more intensive, yet still non-myeloablative conditioning regimens, tandem autologous plus RIC allografts, peripheral blood cells rather than bone marrow, graft engineering to improve the GVM activity while reducing graft-versus-host disease, post-transplant maintenance and targeted conditioning therapies such as bone-seeking radioisotopes.

Myeloablative allogeneic stem cell transplantation for advanced stage multiple myeloma: very long-term follow up of a single center experience

We aimed to review the long-term outcome of myeloablative allogeneic stem cell transplantation (SCT) performed for multiple myeloma (MM) at our institution. Records of all patients who received standard myeloablative allogeneic SCT for MM were retrospectively reviewed. Overall survival (OS), progression-free survival (PFS), and event-free survival (EFS) were calculated using the Kaplan-Meier method. In total 37 transplants had been performed. Median follow up post-SCT was 108 months (range: 33-148). The majority of patients suffered advanced stage disease and/or had received multiple prior therapies prior to SCT. Transplant-related mortality (TRM) at 100 days was 32%. Grades 2-4 acute graft-vs.-host disease (GVHD) occurred in 18 patients (49%), and extensive stage chronic GVHD in seven (28%) of 25 patients surviving greater than day 100. Median OS, PFS, and EFS were 28 months, 66 months and 13 months, respectively, with 5 year OS, PFS, and EFS 40%, 54% and 24%. Our results suggest that allogeneic SCT, even when performed in advanced stage, heavily pretreated MM, still results in long-term EFS in a significant minority of patients. Efforts should continue on alternative allogeneic SCT approaches to reduce the high early TRM rate associated with myeloablative conditioning.

Relapse to prior autograft and chronic graft-versus-host disease are the strongest prognostic factors for outcome of melphalan/fludarabine-based dose-reduced allogeneic stem cell transplantation in patients with multiple myeloma

We evaluated prognostic factors of melphalan/fludarabine-based dose-reduced allografts in patients with multiple myeloma. From 1998 to 2002, 120 patients with multiple myeloma were treated with melphalan/fludarabine followed by allogeneic stem cell transplantation. The cumulative risk at 1 year for treatment-related mortality (TRM) was 18% (95% confidence interval [CI], 12%-28%). In a multivariate analysis, relapse after prior high-dose chemotherapy was the most significant risk factor for TRM (hazard ratio [HR], 2.80; 95% CI, 1.16-6.74; P =.02), relapse (HR, 4.14; 95% CI, 2.04-8.38; P <.001), event-free survival (HR, 3.11; 95% CI, 1.77-5.46; P <.001), and overall survival (HR, 2.69; 95% CI, 1.35-5.35; P =.005). In addition, relapse was also significantly diminished by chronic graft-versus-host disease (GVHD) in a time-dependent Cox model (HR, 0.37; 95% CI, 0.16-0.87; P =.02). At transplantation, 8% of the patients were in complete remission, whereas 27% had progressive disease. After allografting, 49% achieved complete remission, and 38% achieved partial remission. In a subgroup of patients with chemosensitivity at transplantation and no relapse after prior high-dose chemotherapy who underwent transplantation with peripheral blood stem cells (n = 46), the cumulative risk of TRM at 1 year was only 8% (95% CI, 1%-54%). The 2-year estimated event-free and overall survival was 60% (95% CI, 42%-78%) and 75% (95% CI, 59%-91%), respectively, for related donors (n = 34) and was 81% (95% CI, 59%-100%) and 92% (95% CI, 76%-100%), respectively, for unrelated donors (n = 12).

Autografting followed by a reduced-intensity conditioning unrelated donor cord blood transplantation for a patient with refractory multiple myeloma: successful engraftment with minimal toxicity

We report on a 59-yr-old man with recurrent multiple myeloma. To reduce treatment-related mortality, while retaining the cytoreductive effects of high-dose chemotherapy, as well as graft vs. myeloma effect, we used a reduced-intensity conditioning umbilical cord blood (CB) transplantation following high-dose chemotherapy with autologous stem cell transplantation support. This patient was engrafted rapidly and extramedullary toxicities were acceptable. Although he had local recurrence in the right calf on day +130 after the CB transplantation, the tumor was successfully treated with radiation therapy, and he is alive and well at present (day +480).

Progress in allogeneic bone marrow and peripheral blood stem cell transplantation for multiple myeloma: a comparison between transplants performed 1983-93 and 1994-98 at European Group for Blood and Marrow Transplantation centres

Out of 690 allogeneic matched sibling donor transplants for multiple myeloma reported to the European Group for Blood and Marrow Transplantation (EBMT) registry, 334 were performed during the period 1983-93 (all with bone marrow) and 356 during 1994-98 [223 with bone marrow and 133 with peripheral blood stem cells (PBSCs)]. The median overall survival was 10 months for patients transplanted during the earlier time period and 50 months for patients transplanted with hone marrow during the later period. The use of PBSCs was associated with earlier engraftment but no significant survival benefit compared to bone marrow transplants during the same time period. The improvement in survival since 1994 with the result of a significant reduction in transplant-related mortality, which was 38%, 21% and 25% at 6 months and 46%, 30% and 37% at 2 years during the earlier period, and the later period with bone marrow and PBSCs respectively. Reasons for the reduced transplant-related mortality appeared to be fewer deaths owing to bacterial and fungal infections and interstitial pneumonitis, in turn a result of earlier transplantation and less prior chemotherapy. Better supportive treatment and more frequent use of cytokines may also play a role. The improvement in survival was not directly related to the increased use of PBSCs.

Adoptive immunotherapy with antigen-specific T cells in myeloma: a model of tumor-specific donor lymphocyte infusion

Although partial remissions rates of up to 60% are obtained with conventional therapeutic regimens, multiple myeloma is essentially an incurable disease with a median survival of approximately 30 months. Allogeneic stem cell transplantation (SCT) results in a high percentage of complete remissions (CRs), but it can be associated with significant treatment-related mortality. Recent clinical studies have shown that highly immunosuppressive, yet nonmyeloablative, doses of fludarabine-based chemotherapy can result in alloengraftment. However, even with a reduction in treatment-related mortality, success with allogeneic SCT is limited by the significant risk of relapse. The goal of the strategy described is to transfer tumor antigen-specific immunity induced in the stem cell donor to the allogeneic SCT recipient to reduce relapse. Donors are immunized with a well-defined vaccine, specific for the patient's tumor. The allogeneic SCT is performed with a conditioning regimen consisting of cyclophosphamide and fludarabine, and the stem cell source is blood mobilized with filgrastim, which could potentially enhance the transfer of a larger number of tumor-specific T cells in the allograft, as compared to bone marrow. Donor immunization with myeloma idiotype protein in the setting of a nonmyeloablative SCT may represent a novel strategy for the treatment of myeloma.

Myeloablative intensified conditioning regimen with in vivo T-cell depletion (ATG) followed by allografting in patients with advanced multiple myeloma. A phase I/II study of the German Study-group Multiple Myeloma (DSMM)

We investigated toxicity and efficacy of in vivo T-cell depletion with anti-thymocyte globulin (ATG) as part of an intensified myeloablative conditioning regimen followed by allogeneic stem cell transplantation in patients with advanced multiple myeloma. The conditioning regimen consisted of modified total body irradiation, busulfan and cyclophosphamide (n=15) or in the case of prior dose-limiting radiotherapy of busulfan and cyclophosphamide (n=3). The median age was 44 years (range, 29-53) and the median time from diagnosis to transplant was 12 months (range, 6-144). Grade II-IV acute graft-versus-host disease (GvHD) occurred in six patients (35%). Severe grade III/IV GvHD developed in one patient (6%). Three patients died of therapy-related causes (17%). A complete remission (CR) with negative immunofixation after allogeneic transplantation was seen in eight of the evaluable patients (53%). After a median follow-up of 41 months (range, 8-84), the estimated overall survival at 6 years for all patients is 77% (CI 95%: 58-96%). The estimated progression-free survival at 6 years for all patients is 31% (CI 95%: 2-59%) and 46% (CI 95%: 9-83%) for patients with CR. In vivo T-cell depletion with ATG resulted in a low rate of severe GvHD with low treatment-related mortality, and a substantial number of long-term survivors.

High rate of remission and low rate of disease recurrence in patients with multiple myeloma allografted with PBSC from their HLA-identical sibling donors

A total of 30 multiple myeloma patients (M=23, F=7; age 31-55 years, median 48) were allografted with peripheral blood stem cells (PBSC) from HLA-identical siblings. Time to transplantation was 3-107 months (median 8). Prior chemotherapy lines varied from 1 to 6 (median 1). Four patients were in complete remission (CR), 11 in partial remission (PR), 13 were considered to be nonresponders, and two had progressive disease. Most were conditioned with busulfan-melphalan. PBSC were collected by apheresis after G-CSF or sequential GM-CSF and G-CSF. The patients were grafted with 4.4-24.1 x 10(6)/kg CD34+ (median 7.9) and 0.9-7.9 x 10(8)/kg CD3+ cells (median 2.3). GVHD prophylaxis was methotrexate-cyclosporine. Engraftment was complete and rapid. Grades II-IV acute GVHD (aGVHD) developed in 16 (53%), but was grade III-IV only in five (17%); chronic GVHD (cGVHD) developed in 17 out of the 24 evaluable patients (71%). A total of 18 patients (71%) attained CR after transplantation. TRM was 30% overall, 16% at 100 days. There was only one relapse. Overall survival and event-free survival at 73 months were 60% and 67%, respectively. PCR negativity for IgH-gene rearrangement occurred in all persistently CR patients studied. PBSC allograft can induce long remissions, because of profound suppression of the neoplastic clone that is probably linked to the antitumor effect of cGVHD.

Recent developments in hematopoietic stem cell transplantation for multiple myeloma

Multiple myeloma (MM) is often successfully controlled with conventional chemotherapy; however, complete remissions are uncommon, and cure is rare. High-dose therapy followed by administration of autologous or allogeneic stem cells, used for the treatment of MM in the past 15 years, is promising as a means of increasing remission rates and improving survival. Autologous transplantation has not always demonstrated survival benefits in randomized studies because most of the patients receiving transplants have relapses, whereas patients given conventional therapy can receive salvage transplants when relapse occurs. Efforts to improve the results of autologous transplantation include targeted radiation, tandem transplantation, and posttransplantation immunotherapy. Only allogeneic hematopoietic stem cell transplantation is potentially curative, owing to a graft-versus-myeloma effect. Although patients who receive either allogeneic or autologous stem cell transplants for MM have similar 3- to 5-year survival rates, only allograft recipients appear to enjoy long-term disease-free survival. High transplantation-related mortality associated with allogeneic stem cell transplantation is currently the major limitation to wider use of this potentially curative modality. Strategies designed to improve the therapeutic index of allografts include the use of nonablative conditioning regimens, peripheral blood cells rather than bone marrow, graft engineering, and targeted conditioning therapies, such as bone-seeking radioisotopes.

Allogeneic stem cell transplantation after reduced-intensity conditioning in lymphoid malignancies

Allogeneic stem cell transplantation (allo-SCT) is an effective therapeutic option for a wide range of hematological malignancies. The toxicity of the conditioning regimen and graft-versus-host disease (GVHD) occurring after the infusion of the graft remain the most important factors leading to high morbidity and mortality. Reduced-intensity conditioning regimens have recently been developed in an effort to reduce the toxicity associated with conventional allo-SCT while preserving the curative potential of the graft-versus-tumor (GVT) effect. Most patients with lymphoproliferative disorders are not ideal candidates for allo-SCT due to higher age at diagnosis, which together with the advanced stage of disease at the time of transplantation can lead to a high transplant-related mortality (TRM). Preliminary experience indicates that reduced-intensity allo-SCT is feasible in such patients. The immediate TRM is low in comparison with conventional procedures and overall results seem promising, thus indicating the existence of a GVT effect. Nevertheless, all series are still low in numbers and follow-up is too short to draw definitive conclusions. Acute and chronic GVHD remain a significant problem with incidences comparable to the conventional setting in some series. Thus, therapeutic strategies must be sought to decrease GVHD without abrogating the GVT effect.

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.

Unrelated stem cell transplantation in multiple myeloma after a reduced-intensity conditioning with pretransplantation antithymocyte globulin is highly effective with low transplantation-related mortality

We investigated the feasibility of unrelated stem cell transplantation in 21 patients with advanced stage II/III multiple myeloma after a reduced-intensity conditioning regimen consisting of fludarabine (150 mg/m(2)), melphalan (100-140 mg/m(2)), and antithymocyte globulin (ATG; 10 mg/kg on 3 days). The median patient age was 50 years (range, 32-61 years). All patients had received at least one prior autologous transplantation, in 9 cases as part of an autologous-allogeneic tandem protocol. No graft failure was observed. At day 40 complete donor chimerism was detected in all patients. Grade II to IV acute graft-versus-host disease (GVHD) was seen in 8 patients (38%), and severe grade III/IV GVHD was observed in 4 patients (19%). Six patients (37%) developed chronic GVHD, but only 2 patients (12%) experienced extensive chronic GVHD. The estimated probability of nonrelapse mortality at day 100 was 10% and at 1 year was 26%. After allografting, 40% of the patients achieved a complete remission, and 50% achieved a partial remission, resulting in an overall response rate of 90%. After a median follow-up of 13 months, the 2-year estimated overall and progression-free survival rates are 74% (95% CI, 54%-94%) and 53% (95% CI, 29%-87%), respectively. A shorter progression-free survival was seen in patients who already experienced relapse to prior autograft (26% versus 86%, P =.04). Dose-reduced conditioning with pretransplantation ATG followed by unrelated stem cell transplantation provides durable engraftment and donor chimerism, reduces substantially the risk of transplant-related organ toxicity, and induces high remission rates.

Autologous stem cell transplantation followed by a dose-reduced allograft induces high complete remission rate in multiple myeloma

We evaluated toxicity, engraftment, chimerism, graft-versus-host disease (GVHD), and response to a dose-reduced allograft after cytoreductive autografting in 17 patients with advanced stage II/III multiple myeloma (MM). After autografting with melphalan (200 mg/m2) the patients received after a median interval of 119 days (range 60-210) a dose-reduced regimen consisting of fludarabine (180 mg/m2), melphalan (100 mg/m2), and antithymocyte globulin (3 x 10 mg/kg) followed by allografting from related (n = 7), mismatched related (n = 2), or unrelated (n = 8) donors to induce a graft-versus-myeloma effect. After dose-reduced allografting all patients became neutropenic (< 0.2 x 10(9)/L) for at least 8 days. All patients engrafted with a median time for leukocyte (> 1 x 10(9)/L) and platelet (> 20 x 10(9)/L) counts of 16 (range, 11-24) and 23 days (range, 12-43), respectively. Complete donor chimerism was detected after a median of 30 days (range, 19-38). Acute GVHD stage II occurred in 4 patients (25%) and grade III GVHD in 2 patients (13%). Chronic GVHD developed in 40% of the patients, but only 1 patient experienced extensive chronic GVHD requiring further immunosuppressive therapy. Two patients died of alveolar hemorrhage and pneumonia, resulting in a day 100 mortality rate of 11%. The rate of complete remission with negative immunofixation increased from 18% after autografting to 73% after allografting. After a median follow-up of 17 months after autologous and 13 months after allogeneic transplantation 13 patients are alive and 12 of them free of relapse or progression. The tandem auto-allotransplant protocol is highly active and provides rapid engraftment with complete donor chimerism and tolerable toxicity.

Low cost autologous peripheral blood stem cell transplantation performed in a municipal hospital for a patient with plasma cell leukaemia

Autologous peripheral blood stem cell transplantation (PBSCT) is a costly procedure. In India, the cost varies from US$20000 to 25000 and most patients cannot afford it. Using several cost-cutting measures, we were able to treat a patient with plasma cell leukaemia by autologous PBSCT. A 42-year-old-male presented with plasma cell leukaemia. He was treated with VAD therapy, followed by high-dose cyclophosphamide and granulocyte colony-stimulating factor (G-CSF) for mobilization of peripheral blood stem cells. The patient was conditioned with high dose melphalan, followed by autologous PBSCT. The procedure was performed in a municipal hospital in which there was no prior experience with stem cell transplantation. Costs were reduced by: (i) using oral medication whenever possible; (ii) having a relative of the patient prepare his food under medical guidance; (iii) starting G-CSF on day 7 rather than on day 1; (iv) short-term storage of the PBSC in an ordinary refrigerator at 4 degrees C without cryopreservation; (v) infusing a large number of CD34+ cells, which shortened the time to engraftment; (vi) delegating many of the functions of a marrow transplant nurse to a resident physician. The cost of transplantation was thereby reduced to about US$ 6000, with successful engraftment by day +13. The patient remained in remission for 7 months, after which he relapsed and was treated with chemotherapy and electron beam radiation to the skin.

Allogeneic hematopoietic cell transplantation for multiple myeloma

At the present time, allogeneic hematopoetic stem cell transplantation (AHSCT) is the only proven treatment for multiple myeloma (MM) that is potentially curative. This conclusion is based on observations of patients who have undergone AHSCT and are living disease-free for 5-15 years. While patients who receive either allogeneic or autologous stem cell transplants for MM have similar 3-5 year survival, only allograft recipients appear to enjoy long-term disease free survival. This is most likely due to an allogeneic graft-versus-myeloma effect, demonstrated most dramatically by complete responses observed after the simple infusion of donor lymphocytes for patients who have relapsed after a prior allograft. The very high transplant related mortality associated with standard allogeneic stem cell transplantation is currently the major limitation to wider use of this potentially curative treatment modality. Complications are age-related and thus standard AHSCT is offered only to patients under age 55; further limiting the utility of this treatment. The challenge for clinical investigators will be to reduce the incidence of post-transplant complications for patients receiving AHSCT for MM. These strategies include the use of non-ablative conditioning regimens, the use of peripheral blood stem cells rather than bone marrow, graft engineering and targeted conditioning therapies such as bone-seeking radioisotopes. In one such approach, tandem autologous/non-ablative allogeneic transplants have been shown to result in relatively low mortality, high complete response rates and 1-year survivals of 81%. Further follow-up and randomized trials will help to define the utility of this strategy.

Treatment of myeloma: recent developments

Melphalan was the first described treatment for patients with multiple myeloma in the 1960s and is still being used in clinical practice. However, the use of melphalan in combination with prednisone resulted in a median survival of only 2-3 years. Therefore, the dose of melphalan has been intensified since then (140-200 mg/m(2)). In order to diminish treatment-related morbidity and mortality due to severe myelosuppression induced by these regimens, high-dose melphalan is currently supported with autologous stem cells. Indications for high-dose therapy and the role of further intensification by performing second or allogeneic transplantations are discussed. Furthermore, new therapeutic modalities, such as inhibitors of angiogenesis, also showing direct antiproliferative, cytokine-related and immunomodulatory effects on plasma cells (thalidomide and its newer derivatives), inhibitors of the transcription factor NF-kappa B (proteasome inhibitors) and immunotherapy are described.

Predicting long-term (> or = 5 years) event-free survival in multiple myeloma patients following planned tandem autotransplants

Although outcome in multiple myeloma (MM) patients has improved significantly with the introduction of autotransplants (AT), the curability of this approach remained to be demonstrated. Therefore, we analysed outcome and prognostic factors using a logistic regression model in 515 consecutive newly diagnosed and previously treated patients intended to receive melphalan-based tandem transplants with follow up of > or = 5 years. One quarter of patients had event-free survivals (EFS) > or = 5 years with no further relapses seen after 7 years (46 patients on plateau). On multivariate analysis, factors associated with EFS > or = 5 years were absence of chromosome 11 and 13 abnormalities (odds ratio: 6.1), < or = 12 months of preceding standard-dose therapy (SDT) (OR: 2.6) and beta-2 microglobulin (B2M) level < or = 2.5 mg/l at time of first AT (OR: 1.7). Patients with only favourable variables (25%) had a 7-year EFS in excess of 35%, compared with 15% and 10%, respectively, with one (43%) or two unfavourable variables (27%), and 0% for 5% of patients with three unfavourable variables (P < 0.0001). Using a 1-year landmark analysis to allow for guaranteed time and thereby excluding early treatment failures, attaining a complete remission (CR) had no significant effect on long-term survival. Our data are consistent with cure in MM patients with a CR duration . or = 7 years and re-establishment of a monoclonal gammopathy of undetermined significance (MGUS) phase in those with persistent evidence of disease post transplantation, but without disease progression > or = 7 years.

Allogeneic transplantation for multiple myeloma: further evidence for a GVHD-associated graft-versus-myeloma effect

We report a series of 37 consecutive patients with multiple myeloma (MM) who received an allograft between 1990 and 2000 at our institution. Median age was 47 years, and nearly 70% of patients were Durie-Salmon stage III. A median of five cycles of chemotherapy were given before transplant, with a median interval between diagnosis and transplant of 9.3 months. We report a nonrelapse mortality rate of 22% with a median follow-up period of 40 months, whereas complete remission (CR) rate at 12 months is estimated at 57%. Treatment failure rate and overall survival at 40 months are estimated at 52% and 32%, respectively. The number of chemotherapy cycles prior to allotransplantation achieved borderline statistical significance as a poor prognosis factor for overall survival (P = 0.05), while the presence of chronic graft-versus-host disease (cGVHD) was significantly correlated with CR achievement (P = 0.036). Our study confirms that early allografting in MM can yield toxicity rates significantly lower than those associated with historical cohorts, and supports the hypothesis that cumulative chemotoxicity has a negative influence on mortality and survival rates. More importantly, our study clearly demonstrates an association between cGVHD and CR and brings further evidence in favor of a graft-versus-myeloma effect.

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.

Allogeneic hematopoietic cell transplantation for multiple myeloma

Some patients with multiple myeloma (MM) who have undergone allogeneic hematopoietic stem cell transplants remain free of disease 5 to 13 years later-a major accomplishment for a malignancy that had been resistant to all investigational therapies. Although it will require longer follow-up to determine how many are truly cured, results for patients with MM transplanted from identical twins suggest that long-term progression-free survival is possible. While 3- to 5-year survival is similar after allogeneic or autologous stem cell transplant for MM, only allograft recipients appear to enjoy long-term disease-free survival, most likely due to an allogeneic graft-versus-myeloma (GVM) effect. The very high transplant-related mortality associated with standard allogeneic stem cell transplantation is currently the major limitation to wider use of this potentially curative treatment. The challenge for clinical investigators will be to reduce the incidence of posttransplant complications. Strategies include the use of nonablative conditioning for allografts, the administration of peripheral blood stem cells (PBSC) rather than bone marrow, and the application of more focused, targeted conditioning therapies such as bone-seeking radioisotopes.

European Group for Blood and Marrow Transplantation Registry studies in multiple myeloma

The European Group for Blood and Marrow Transplantation (EBMT) Myeloma Registry, established in 1987, contains data on 1,368 allogeneic and more than 8,000 autologous stem cell transplants performed since 1983. Among autologous transplant patients, the median survival after transplantation is 50 months, and the actuarial survival at 10 years is 30%, with a plateau appearing at about 8 years. Factors of importance for a more favorable prognosis are lower age, response to chemotherapy, only one course of primary chemotherapy, stage I or II disease, and low beta(2)-microglobulin at diagnosis. Beneficial procedural factors associated with better outcome are a preparative regimen without total body irradiation (TBI), posttransplant interferon alfa maintenance treatment, and possibly tandem transplantation. In vitro graft purging, using CD34(+) selection, does not have any impact on survival. A case-matched analysis comparing autologous and allogeneic transplantation demonstrated significantly better survival in the former group, with median posttransplant survival times of 36 months and 18 months in the autologous and allogeneic groups, respectively. This result was in turn due to a markedly lower incidence of transplant-related death among the autotransplant patients: 13%, versus 41% for the allogeneic group. However, recent data on allogeneic transplants performed from 1994 to 1998 has demonstrated a decrease in treatment-mortality to 30%, and this has resulted in a prolongation of survival; in this analysis, the results are similar irrespective of the type of graft used, allogeneic bone marrow or blood stem cells. In a small case-matched analysis, transplantation with an identical twin donor was superior to both allogeneic and autologous transplantation with respect to survival and freedom from progression.

Peripheral blood stem cells for allogeneic transplantation: a review

Peripheral blood stem cells (PBSCs) have become increasingly popular for use in hematopoietic stem cell transplantation. PBSCs are readily collected by continuous-flow apheresis from patients and healthy donors after the administration of s.c. recombinant colony-stimulating factors with only minimal morbidity and discomfort. Although the precise identification of PBSCs remains elusive, they can be phenotypically identified as a subset of all circulating CD34(+) cells. There are important phenotypic and biologic distinctions between PBSCs and bone marrow (BM)-derived progenitor cells. PBSCs express more lineage-specific antigens but are less metabolically active than their BM-derived counterparts. The use of PBSCs for allogeneic transplantation has been compared to BM in several randomized trials and cohort studies. The use of PBSCs in leukemia, myeloma, non-Hodgkin's lymphoma, and myelodysplasia has resulted in shorter times to neutrophil and platelet engraftment at the expense of increased rates of chronic graft-versus-host disease. The increase in graft-versus-host disease is mainly due to a log-fold increase in donor T cells transferred with the graft. Relapse rates after transplantation may be lower after PBSC transplantation but a convincing survival advantage has not been demonstrated overall. It is possible that a stronger graft-versus-tumor effect may exist with PBSCs when compared with BM although the mechanisms leading to this effect are not clear.

High response rate in refractory and poor-risk multiple myeloma after allotransplantation using a nonmyeloablative conditioning regimen and donor lymphocyte infusions

Standard allogeneic stem cell transplant (allo-SCT) regimens have been associated with a high transplant-related mortality (TRM) in multiple myeloma (MM). Nonmyeloablative therapy can establish stable engraftment after allo-SCT and maintain the antitumor effect with less toxicity, which is important in heavily pretreated and elderly patients. We report on 16 poor-risk MM patients receiving allo-SCT from an HLA-matched (n = 14) or mismatched (n = 2) sibling following conditioning with melphalan 100 mg/m(2) (MEL-100). Ten patients had refractory relapse, 4 responsive relapse, and 2 patients were in near complete remission (nCR) with poor-prognosis disease. Patients had received 1 (n = 9) or 2 (n = 7) prior autotransplants. Donor lymphocyte infusions (DLIs) were given to 14 patients with no clinical evidence of graft versus host disease (GVHD) either to attain full donor chimerism (n = 4) or to eradicate residual disease (n = 10). Fifteen patients showed myeloid engraftment, and 12 patients were full donor chimeras at day +21. No TRM was observed during the first 100 days. Acute GVHD developed in 10 patients; 1 had fatal grade IV GVHD. Seven progressed to chronic GVHD, limited in 3 and extensive in 4 patients. At a median follow-up of 1 year, 5 patients achieved and sustained CR, 3 nCR, and 4 partial remission. Of 4 patients progressing after transplantation, 3 achieved a remission following further chemotherapy and DLI. Remarkable graft versus myeloma responses were seen in chemotherapy-refractory patients. Two patients died of progressive disease, and 3 died of GVHD complications without active disease. GVHD remains a major problem with this procedure.

Allogeneic haemopoietic stem cell transplantation for multiple myeloma or plasma cell leukaemia using fractionated total body radiation and high-dose melphalan conditioning

We have evaluated the outcome of allogeneic haemopoietic stem cell transplantation for multiple myeloma using a conditioning regimen comprising fractionated total body irradiation and high-dose melphalan (110 mg/m2). The study comprised 25 patients (median age 49 years) who had been transplanted by either bone marrow (n = 13) or G-CSF mobilized peripheral blood stem cells (n = 12). Overall transplant-related mortality was 30% but was lower for patients < 50 years of age at transplant (21%). The main cause of treatment-related mortality was viral infection. Of the 19 patients evaluable post-transplant, 17 have so far achieved complete remissions. Currently, with a median follow-up of 3.4 years, 18 out of 25 patients are alive, of whom 15 are in continuing complete remission (CR) and 2 in second remission after suffering localized relapses, which were treated with radiotherapy and donor leucocyte infusions. Patients transplanted after 1 line of previous therapy, < 50 years of age and receiving peripheral blood stem cells (PBSC) rather than bone marrow (BM) had a superior outcome, although there was no statistically significant factor. We conclude that allogeneic transplantation should be considered as a potentially curative option for younger patients with myeloma and that the regimen using fractionated total body irradiation and melphalan has a high CR rate and a relatively low risk of treatment-related mortality, particularly in younger patients.

Different immune reconstitution in multiple myeloma, chronic myeloid leukemia and acute myeloid leukemia patients after allogeneic transplantation of peripheral blood stem cells

In this study we compared the lymphocyte reconstitution in 13 multiple myeloma (MM), nine acute myeloid leukemia (AML) and 10 chronic myeloid leukemia (CML) patients after allogeneic G-CSF-mobilized PBSC transplantation from HLA-identical siblings. Conditioning regimens included standard total body irradiation + cyclophosphamide (CY), or busulphan + CY, whereas VP-16 was added in patients with advanced disease. Overall comparable numbers of mononuclear cells, CD34+ cells and CD3+ T cells were infused in each group. A significantly higher CD3+ T cell number was observed in MM and AML than in CML patients 1 month after transplant. However, MM patients showed a faster and better recovery of CD4+ T cells than both AML and CML patients at 3 months (P = 0.01 and P = 0.01, respectively) and 12 months (P = 0.01 vs AML, while P = NS vs CML) after transplant, and had a CD4:CD8 ratio > 1 with a median CD4+ T cell value > 400/microl 1 year after transplant. Development of acute graft-versus-host disease (GVHD) did not affect CD4:CD8 ratios but patients who experienced acute GVHD > grade I had lower CD4+ and CD8+ T cell numbers at all time points. However, after excluding patients with GVHD > grade I, MM patients still showed a significantly higher CD4+ T cell value than patients with myeloproliferative diseases 1 year after transplant. These findings suggest that although allogeneic PBSC transplantation induces rapid immune reconstitution, different kinetics may occur among patients with hematological malignancies. In particular, the rapid reconstitution of CD4+ T cells in MM patients may contribute to the low transplant-related mortality achieved in this disease.

Progress in haematopoietic stem cell transplantation for multiple myeloma

High-dose myeloablative treatment followed by autologous haematopoietic stem cell transplantation has significantly improved survival of patients younger than 65 years of age with multiple myeloma as compared with conventional chemotherapy. However, all patients seem to relapse and molecular remissions are rare. Results of allogeneic transplantation, still hampered by high transplant-related mortality, have improved dramatically over the last 5-6 years and this is an option for patients younger than 50-55 years old. The relapse rate is lower than with autologous transplantation and molecular remissions are frequent. Some patients are still in complete haematological remission more the 10 years following transplantation. Autologous transplantation followed by nonmyeloablative allogeneic transplantation is on trial and may be a way to eventually cure a fraction of younger patients with multiple myeloma.

The Role of Allogeneic Transplantation in the Treatment of Multiple Myeloma

In multiple myeloma (MM) attempts to improve upon the results of standard melphalanpredisone with other conventional dose drug combinations, have generally been unsuccessful, producing only minor improvements in response rate, with little effect on survival. The only treatment capable of producing a dramatic change in response and life expectancy is high-dose chemo-radiotherapy followed by stem cell transplantation. However, after autologous transplant relapse will almost inevitably occur, and freedom from recurrence curves show no plateau in most studies. Besides the resistance of the disease to chemotherapy, another possible explanation is tumor contamination of the graft. This is one major advantage of allogeneic transplantation over autologous, the other being an immune mediated mechanism of tumor suppression in part related to GVHD. Application of allogeneic transplantation to MM has met a number of obstacles, but is now entering a phase of reappraisal, due in part to a tendency to earlier transplantation, in part to the use of novel technologies such as allogeneic peripheral blood stem cells instead of marrow. The goal should be the reduction of transplant related deaths, to better exploit the higher eradication potential of allogeneic cell therapies. The most intriguing perspectives are those related to immune manipulation of recipient and/or donor.