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

Antithymocyte globulin induces complement-dependent cell lysis and caspase-dependent apoptosis in myeloma cells

OBJECTIVE

Allogeneic stem cell transplantation is a potentially curative therapy for patients with multiple myeloma. Polyclonal antithymocyte globulins (ATG) or monoclonal anti-CD52 (Alemtuzumab) are included in conditioning regimens to enhance engraftment and reduce risk of severe graft-vs-host disease. Because both agents have been reported to induce depletion of B cells, we sought to investigate their cytotoxic activity on myeloma cells.

MATERIALS AND METHODS

Complement-mediated and complement-independent activity of ATG-Fresenius and Alemtuzumab was investigated on four myeloma cell lines (RPMI-8226, U266, KMS-12-BM, and EJM) and bone marrow samples from six myeloma patients. Cytotoxicity was determined by staining with annexin V-fluorescein isothiocyanate and 7-amino-actinomycin D followed by flow cytometry.

RESULTS

ATG at a concentration of 500 microg mL(-1) induced up to 100% and 85% complement-dependent killing of myeloma cell lines and primary myeloma samples respectively. In the absence of complement ATG still could induce up to 50% and 80% apoptosis in myeloma cell lines and primary myeloma samples, respectively. Preincubation of myeloma cells with a general caspase inhibitor abrogated ATG-induced complement-independent cell death. Alemtuzumab-mediated myeloma cytotoxicity was only observed in KMS-12-BM cells, and in none of the patient samples.

CONCLUSION

ATG induces marked cytotoxic activity both in myeloma cell lines and in primary myeloma samples. Further elucidation of antibodies and antigens involved may pave the way for antibody-based myeloma therapy.

Long-term outcome of nonmyeloablative allogeneic transplantation in patients with high-risk multiple myeloma

Conventional treatment or autologous transplantation has not been able to achieve long-term remission in patients with multiple myeloma (MM). Nonmyeloablative allogeneic transplantation might offer an option for cure without the high mortality associated with conventional conditioning. Here we present a retrospective analysis of patients with high-risk MM treated with nonmyeloablative allogeneic transplantation. In all, 52 patients with relapsed MM or high-risk features at diagnosis received 2 Gy TBI alone (n=3) or with fludarabine (n=49) as conditioning. Patients were heavily pretreated with a median of eight cycles of conventional chemotherapy and one or more autologous transplants for all but one patient. Regimen-related toxicity was low. Acute graft-versus-host disease II-IV occurred in 37% of patients, and 70% experienced chronic graft-versus-host disease (cGvHD). Median follow-up was 567 days, and transplant-related mortality was 17% in total. Estimated progression-free and overall survival at 18 months was 29.4 and 41.1%, respectively. Patients with cGvHD had a significantly higher progression-free survival, as did patients with up to eight cycles of pretreatment chemotherapy vs those with nine or more. In this highly pretreated patient group, disease control was unsatisfactory and our results suggest that a potential strategy might be to perform allogeneic transplant earlier in the course of the disease.

Reduced-intensity allogeneic stem cell transplantation in adults and children with malignant and nonmalignant diseases: end of the beginning and future challenges

During the last 10 years, multiple studies using reduced-intensity (RI) conditioning followed by allogeneic stem cell transplantation (AlloSCT) have been reported in adult and, less so, pediatric recipients. RI AlloSCT allegedly eradicates malignant cells through a graft-versus-leukemia/graft-versus-tumor effect provided by alloreactive donor T lymphocytes, natural killer cells, or both. Various studies have clearly demonstrated a graft-versus-leukemia/graft-versus-tumor effect in hematologic malignancies and solid tumors. Acute short-term toxicity, including infection and organ decompensation after myeloablative conditioning therapy, can result in a significant incidence of early transplant-related mortality. More importantly, long-term late effects-including growth retardation, infertility, and secondary malignancies-are major complications after myeloablative conditioning therapy, especially in vulnerable children, who are more susceptible to these complications. Recent results comparing RI conditioning with myeloablative conditioning followed by HLA-matched sibling AlloSCT have demonstrated a significant reduction in use of blood products, risk of infections, transplant-related mortality, length of hospitalization, and feasibility of conditioning therapy in outpatient settings. Despite the success of RI AlloSCT, large prospective randomized multicenter studies are necessary to define the appropriate patient population, optimal conditioning regimens and pretransplantation immunosuppression, role of donor lymphocyte infusions, duration of hospitalization, overall survival, cost-benefit ratio, and differences in long-term effects to evaluate the role of RI AlloSCT more fully. We review the recent experience of RI AlloSCT in adults and children with both malignant and nonmalignant diseases and discuss the challenges for the future.

Evolving Role of Stem Cell Transplantation in Multiple Myeloma

Autologous stem cell transplantation (ASCT) is currently considered the standard of care for younger patients with newly diagnosed multiple myeloma based on 3 randomized trials that have shown it is superior to conventional chemotherapy. However, the introduction of novel agents like thalidomide, bortezomib, or lenalidomide may improve the results of standard-dose therapy. For instance, in combination, melphalan/prednisone/thalidomide yields complete response rates comparable with those achieved with ASCT. Different strategies have been proposed to improve the results of ASCT. A randomized trial has shown that tandem ASCT is superior to single ASCT in terms of event-free survival (EFS) and overall survival. Four other randomized trials have produced results in favor of tandem ASCT. However, the benefit remains marginal and patients with poor initial characteristics still have poor outcomes. Further intensification has been tested with encouraging results in patients with high b2-microglobulin levels and chromosome 13 deletion. "Total Therapy II" with intensified induction and post-ASCT chemotherapy also appears to improve outcomes. Another possibility is the use of novel agents in combination with ASCT as part of induction therapy or as maintenance therapy after ASCT. Preliminary results of a French Intergroup study show a significant prolongation of EFS in patients receiving maintenance therapy with thalidomide. Results achieved with allogeneic stem cell transplantation remain disappointing. Although initial results of ASCT followed by reduced-intensity allogeneic stem cell transplantation were promising, with more follow-up, relapses and chronic graft-versus-host disease have limited the enthusiasm. Allogeneic stem cell transplantation should be proposed only in the context of a clinical trial.

Comparison between antithymocyte globulin and alemtuzumab and the possible impact of KIR-ligand mismatch after dose-reduced conditioning and unrelated stem cell transplantation in patients with multiple myeloma

We compared antithymocyte globulin (ATG) with alemtuzumab in 73 patients with multiple myeloma, who underwent reduced conditioning with melphalan/fludarabine, followed by allogeneic stem cell transplantation from human leucocyte antigen-matched or -mismatched unrelated donors. The ATG group had more prior high-dose chemotherapies (P < 0.001), while bone marrow was used more as the stem cell source in the alemtuzumab group (P < 0.001). Alemtuzumab resulted in faster engraftment of leucocytes (P = 0.03) and platelets (P = 0.02) and in a lower incidence of acute graft versus host disease (GvHD) grades II-IV (24% vs. 47%, P = 0.06). More cytomegalovirus (CMV) seropositive patients in the alemtuzumab group experienced CMV reactivation (100% vs. 47%, P = 0.001). The cumulative incidence of treatment-related mortality at 2 years was 26% [95% confidence interval (CI) = 12-37%] for ATG vs. 28% (95% CI = 15-55%) for alemtuzumab, P = 0.7. There was no significant difference in the estimated 2-year overall and progression-free survival between ATG and alemtuzumab: 54% (95% CI: 39-75%) vs. 45% (95% CI: 28-73%) and 30% (95% CI: 16-55%) vs. 36% (95% CI: 20-62%) respectively. In multivariate analysis, treatment with alemtuzumab had a higher risk for relapse (hazard ratio: 2.37; P = 0.05) while killer immunoglobulin-like receptor (KIR)-ligand mismatch was protective for relapse (P < 0.0001). We conclude that alemtuzumab produced less acute GvHD, but higher probability of relapse. The data implicated a major role of KIR-ligand mismatched transplantation in multiple myeloma.

Allogeneic T lymphocytes as a source of peptide-dependent T cells specific for myeloma cells

We investigated the generation of myeloma-specific CTLs from normal donors HLA mismatched with the myeloma cell line SBN. The T-cell line obtained was cloned and each CTL was assessed against SBN and SBN-EBV (a B-EBV cell line obtained by EBV infection of B cells from SBN patient) simultaneously. Among >270 clones evaluated, 2 CTLs (Vbeta13.1 and Vbeta17) killed SBN but spared SBN-EBV cells. Antibodies against HLA-I, but not HLA-A2, molecules abrogated their recognition of SBN. Moreover, SBN recognition was abrogated by anti-HLA-Cw6 antiserum. Both clones recognized two other HLA-Cw*0602 myeloma cell lines. Neither of them recognized HLA-Cw*0602 B-EBV cell lines, the PBMCs of HLA-Cw*0602-unrelated donors or HLA-Cw*0602 melanoma cell lines. We showed that HLA-Cw6 molecules were more expressed at the cell surface of B-EBV cells as compared with myeloma cells, suggesting that the lack of reactivity against B-EBV cells was not related to a low level of HLA expression. Since CTL clones did not express any KIR or NKG2D, we excluded the fact that NK cell receptors could be involved in myeloma-specific recognition through KIR-HLA-I or NKG2D-MICA,B interactions. Cold target competition and acid elution experiments confirmed that myeloma cell recognition was peptide dependent.

Antilymphocyte/thymocyte globulin for graft versus host disease prophylaxis: efficacy and side effects

Antilymphocyte/thymocyte globulins (ALGs/ATGs) have now been used for over 30 years in the setting of hemopoietic stem cell transplants (HSCT), with the aim of preventing graft-versus-host disease (GvHD). This is true especially for transplants from alternative donors. In this review, we will be discussing available published and unpublished data on the advantages and disadvantages of using ALG/ATG before or after an allogeneic HSCT. These studies show that ALG/ATG significantly reduce the incidence and severity of acute and chronic GvHD. Unfortunately, they also show that immune deficiency is a more prolonged and infectious complication more frequent in patients receiving ALG/ATG, suggesting the importance of aggressive monitoring of viral and fungal infections. In particular, the emerging problem of Epstein-Barr virus (EBV) infections and EBV-related lymphoproliferative disorders will be discussed, together with the use of pre-emptive therapy with rituximab. I personally believe ALG/ATG has an important role in allogeneic HSCT, especially today with the increasing use of peripheral blood transplants and the consequent high risk of chronic GvHD. ALG/ATG should be used with caution, and the negative consequences must be understood and possibly prevented.

Stem cell transplantation in multiple myeloma (0, 1, or 2)

PURPOSE OF REVIEW

Autologous stem cell transplantation is now considered the standard of care in patients with multiple myeloma up to 65 years of age. Therefore, two questions have been recently addressed by cooperative groups: should autologous stem cell transplantation be offered to older patients, and is it possible to improve the results of autologous stem cell transplantation, especially with double autologous stem cell transplantation? The results of allogeneic transplantation remain disappointing, with a high transplant-related mortality rate, increasing the need to explore new strategies such as reduced-intensity conditioning.

RECENT FINDINGS

A randomized Italian study confirms that two courses of intermediate-dose melphalan supported by autologous stem cell transplantation is superior to standard melphalan-prednisone even in patients aged 65 to 70. The Intergroupe Francophone du Myelome 94 (IFM94) trial shows that double transplantation is superior to single transplantation, at least in patients with less than 90% reduction of their M-component after one transplant. Several studies have addressed the issue of prognostic factors in the context of autologous stem cell transplantation. A prospective Dutch trial confirms poor results with T cell-depleted allogeneic transplantation prepared by a standard myeloablative regimen. The Seattle group, on the other hand, reports encouraging preliminary data with tandem auto/mini-allotransplantation.

SUMMARY

The available results of randomized studies are in favor of tandem autologous transplantation. In the near future, ongoing studies will clarify the role of novel agents (thalidomide and its analogs, bortezomib) in the context of autologous stem cell transplantation and the place of tandem auto/mini-allotransplantation compared with tandem autologous transplantation.

Reduced-Intensity Conditioning Allogeneic Stem Cell Transplantation for Multiple Myeloma: Results from the Japan Myeloma Study Group

We conducted a retrospective survey of multiple myeloma (MM) patients who underwent reduced-intensity conditioning allogeneic stem cell transplantation (RIST) at 11 hospitals participating in the Japan Myeloma Study Group. Forty-five patients (median age, 53 years) were included in this study. The conditioning regimen consisted of a fludarabine-based regimen in 24 patients and a regimen based on total body irradiation (1-2 Gy) in 18 patients. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and tacrolimus in 28 and 17 patients, respectively. All patients showed myeloid engraftment. Complete chimerism was obtained in 42 patients. Grade II to IV acute GVHD developed in 28 (65%) of 43 patients evaluated, and chronic GVHD developed in 31 (76%) of 41 patients. Early death before day 100 was observed in 4 patients (8.8%). A complete response (CR) was obtained in 12 patients. The factors affecting overall survival were severe acute GVHD and the response after RIST. To date, 18 patients are alive, with 9 patients remaining in CR at a median follow-up of 25 months. The overall and progression-free survival rates at 3 years were 38.5% and 18.8%, respectively. These observations suggest that RIST is feasible with reliable donor engraftment and relatively low transplantation-related mortality in Japanese MM patients.

Unrelated donor hematopoietic stem cell transplantation for patients with hematologic malignancies using a nonmyeloablative conditioning regimen of fludarabine, low-dose total body irradiation, and rabbit antithymocyte globulin

Hematopoietic stem cell chimerism can be established after low-dose conditioning regimens, although the risk of donor cell rejection increases for unrelated donor transplantations. We added pretransplantation rabbit antithymocyte globulin (6 mg/kg) to an established conditioning regimen of fludarabine (90 mg/m2) and single-fraction total body irradiation (200 cGy) followed by postgrafting immunosuppression with cyclosporine A and mycophenolate mofetil for 22 patients with hematologic malignancies. One patient rejected the graft and successfully underwent transplantation with cells from a second donor by using the same conditioning regimen. The actuarial probability of developing acute graft-versus-host disease grade II to IV before day 100 was 40%, although 9 of 14 patients who survived beyond 100 days developed chronic graft-versus-host disease. These data support a hypothesis that the addition of antithymocyte globulin decreases the risk of graft-versus-host and host-versus-graft reactions when combined with a nonmyeloablative conditioning regimen of fludarabine and total body irradiation.

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).

Outcome of unrelated transplants in patients with multiple myeloma

The outcome of patients with multiple myeloma treated with standard therapy is disappointing, with a historical median survival of 3 years. Although high-dose therapy with autologous stem cell transplant has improved treatment outcomes, cure is unlikely. Allogeneic transplant provides a tumor-free graft and a graft-versus-myeloma effect. However, only a minority of patients has a compatible sibling donor. Unrelated hematopoietic stem cell transplant is another option. We analyzed the outcome of patients who received an unrelated bone marrow transplant facilitated by the National Marrow Donor Program (NMDP). Between 1989 and 2000, 71 patients received a myeloablative unrelated transplant for multiple myeloma; 70 patients consented for this analysis. The median recipient age was 44 years. A total of 31% of patients had received a prior autologous transplant. In all, 91% of patients engrafted. The 3-year cumulative incidence estimate of relapse was 34+/-10%. The incidence of Grade II-IV GVHD was 47%. The Kaplan-Meier estimate for overall survival at 5 years was 9+/-7%. The 100-day treatment-related mortality was 42%. In multivariate analysis, only a male donor was a significant predictor for survival. Better strategies are needed to treat patients with multiple myeloma, perhaps by using less-toxic, nonmyeloablative conditioning regimens.

Antithymocyte Globulin Induces Ex Vivo and In Vivo Depletion of Myeloid and Plasmacytoid Dendritic Cells

We investigate the in vivo and ex vivo effect of rabbit antithymocyte globulin (ATG) on myeloid dendritic cells (MDCs) and plasmacytoid dendritic cells (PDCs). After incubation with ATG and complement, the mean number of MDCs and PDCs decreases from 3,168 to 739 x 10/mL (P=0.004) and from 5,314 to 790 x 10/mL (P=0.01), respectively. In vivo ATG given as part of the conditioning regimen before allogeneic stem-cell transplantation induces a stronger reduction of circulating MDCs and PDCs than chemotherapy alone (reduction: 100% vs. 78%-98%). These data show that ATG induces depletion of circulating MDCs and PDCs, which might be in addition to the T-cell depletion a further mechanism to reduce graft-versus-host disease after allogeneic stem-cell transplantation.

Oral cryotherapy for the prevention of high-dose melphalan-induced stomatitis in allogeneic hematopoietic stem cell transplant recipients

GOALS

The purpose of this study was to evaluate the efficacy of oral cryotherapy to prevent high-dose melphalan-induced stomatitis.

PATIENTS AND METHODS

Eighteen consecutive recipients of allogeneic hematopoietic stem cell transplant conditioned with high-dose melphalan (140 mg/m2) in combination with fludarabine alone or with fludarabine and additional chemotherapy or radiation were enrolled. The severity of stomatitis was graded according to the National Cancer Institute Common Toxicity Criteria. Patients were kept on oral cryotherapy using ice chips and ice-cold water shortly before, during, and for additional 90 min after completion of melphalan administration.

RESULTS

Only two of 18 patients (11.1%) developed grade 2 or 3 stomatitis while six of seven patients in the historical control developed it (85.7%; P=0.001).

CONCLUSION

These results suggested that oral cryotherapy could effectively prevent stomatitis caused by high-dose melphalan, and we recommend that it should be incorporated into the conditioning regimen with high-dose melphalan.

Low-dose thalidomide and donor lymphocyte infusion as adoptive immunotherapy after allogeneic stem cell transplantation in patients with multiple myeloma

To improve the antimyeloma effect of donor lymphocyte infusion (DLI) after allogeneic stem cell transplantation in multiple myeloma, we investigated in a phase 1/2 study the effect of low-dose thalidomide (100 mg) followed by DLI in 18 patients with progressive disease or residual disease and prior ineffective DLI after allografting. The overall response rate was 67%, including 22% complete remission. Major toxicity of thalidomide was weakness grade I/II (68%) and peripheral neuropathy grade I/II (28%). Only 2 patients experienced mild grade I acute graft versus host disease (aGvHD) of the skin, while no grades II to IV aGvHD was seen. De novo limited chronic GvHD (cGvHD) was seen in 2 patients (11%). The 2-year estimated overall and progression-free survival were 100% and 84%, respectively. Adoptive immunotherapy with low-dose thalidomide and DLI induces a strong antimyeloma effect with low incidence of graft versus host disease. (Blood. 2004;104:3361-3363)

Thalidomide salvage therapy following allogeneic stem cell transplantation for multiple myeloma: a retrospective study from the Intergroupe Francophone du Myélome (IFM) and the Société Française de Greffe de Moelle et Thérapie Cellulaire (SFGM-TC)

Thalidomide is effective in multiple myeloma (MM), even in patients who have relapsed after high-dose therapy. A potent graft-versus-myeloma (GVM) effect can be induced against MM after allogeneic stem cell transplantation (allo-SCT). In all, 31 MM patients received thalidomide as a salvage therapy after progression following allo-SCT. The median maximum daily dose of thalidomide was 200 mg (range, 50-600). Thalidomide had to be discontinued in six patients (19%) because of toxicity. In all, nine patients (29%; 95% CI, 13-45) achieved an objective response with thalidomide therapy (six partial and three very good partial responses, VGPR). Five patients developed graft-versus-host disease (GVHD) after thalidomide therapy, including the three patients achieving a VGPR. These data demonstrate that thalidomide is potentially effective in MM patients failing allo-SCT.

Thalidomide for the treatment of multiple myeloma

Although thalidomide was withdrawn in the 1960s after its teratogenic property was recognized, it was subsequently found that this drug possesses immunomodulatory and anti-inflammatory effects. Recent studies have also demonstrated that thalidomide has antineoplastic activity via an antiangiogenic mechanism. Observations in the late 1990s that the microenvironment in the bone marrow plays a role in tumor progression in multiple myeloma provided an impetus to use thalidomide for the treatment of this disease. It is known that thalidomide monotherapy is effective in one-third of refractory cases, and in combination with glucocorticoids and/or antineoplastic drugs, thalidomide provides a response rate of more than 50%. Thus, thalidomide therapy is considered a standard approach for the treatment of relapsed and refractory myeloma. The exact mechanism of the antimyeloma effect of thalidomide is not yet clearly understood. Anti-angiogenic effects, direct activity in tumor cells such as the induction of apoptosis or G1 arrest of the cell cycle, the inhibition of growth factor production, the regulation of interactions between tumor and stromal cells, and the modulation of tumor immunity have been considered as possible mechanisms. In addition to its teratogenicity, the adverse effects of thalidomide have been general symptoms such as somnolence and headache, peripheral neuropathy, constipation, skin rash, and other symptoms. Although these adverse effects are generally reversible and mild, grade 3 and 4 toxicities such as peripheral neuropathy, deep venous thrombosis, neutropenia, and toxic dermal necrosis have occasionally been reported. The application of thalidomide therapy in patients with multiple myeloma is being broadened to include not only cases of refractory myeloma, but also previously untreated cases, as well as for maintenance therapy after hematopoietic stem cell transplantation and for the treatment of other hematological diseases. The safe use of this drug will depend on the establishment of diagnostic and treatment guidelines. In addition, the establishment of a nation-wide regulation system is urgently needed in Japan.

Molecular monitoring of minimal residual disease in patients with multiple myeloma

Improvement of transplantation strategies and a multitude of emerging novel therapies result in a better treatment outcome in patients with multiple myeloma (MM). This gives rise to the need for sensitive methods to detect minimal residual disease (MRD) in MM. Qualitative molecular monitoring using allele-specific oligonucleotide PCR for the immunoglobulin heavy chain (IgH) is well established to detect clonotypic cells after therapy or in stem cell harvests. Recently, real-time IgH PCR or limiting dilution based PCR assays offer the possibility to quantify the amount of residual tumour cells. In this review, different qualitative and quantitative IgH PCR techniques will be discussed as well as the current clinical role of molecular monitoring of MRD in patients with MM.

Stem cell transplantation-harnessing of graft-versus-malignancy

PURPOSE OF REVIEW

Allogeneic transplantation can cure a number of hematologic malignancies; however, the cost in morbidity and mortality is high. Much of the toxicity is a direct consequence of the intensity of the conditioning regimen. It has gradually been recognized that the conditioning regimen is important but not critical for the success of transplantation, particularly in the less aggressive hematologic malignancies. The graft-versus-malignancy effect, that is, the recognition of residual cancer cells by the T cells of the donor, is a critical component of the transplantation process.

RECENT FINDINGS

This effect has been emphasized over high-dose therapy by using less intensive, and therefore less toxic conditioning regimens, thus allowing the graft-versus-malignancy effect to predominate. Reduced-intensity conditioning regimens have allowed the application of transplantation to older patients and to patients with underlying medical problems that preclude full-dose transplantation.

SUMMARY

Although the long-term results of this type of approach have not yet been defined, it appears to be effective in diseases such as chronic myelogenous leukemia, chronic lymphocytic leukemia, and low-grade lymphomas that are not intrinsically very aggressive. Although the therapy appears to be valuable, concerns about delayed immune reconstitution and graft-versus-host disease remain.

Graft-versus-myeloma effect following antithymocyte globulin-based reduced intensity conditioning allogeneic stem cell transplantation

In all, 41 multiple myeloma (MM) patients received an antithymocyte globulin (ATG), fludarabine, and busulfan-based reduced intensity conditioning (RIC) for allogeneic stem cell transplantation (allo-SCT) from HLA-identical siblings. In total, 29 patients (70%) were in partial remission, one patient in complete remission, and 11 (27%) with progressive disease at the time of allo-SCT. Median time between diagnosis and allo-SCT was 24 months. The cumulative incidences of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) were 36% (95% CI, 21-51%) and 7% (95% CI, 2-20%), respectively. Overall, 10 patients developed limited chronic GVHD, whereas seven developed an extensive form (cumulative incidence, 41% (95% CI, 26-56%) at 2 years). With a median follow-up of 389 days, the overall cumulative incidence of transplant-related mortality (TRM) was 17% (95% CI, 6-28%). In all, 11 patients (27%) are in continuous complete remission, and the Kaplan-Meier estimates of overall survival (OS) and progression-free survival (PFS) at 2 years were 62% (95% CI, 47-76%) and 41% (95% CI, 23-62%), respectively. PFS and OS were significantly higher in patients with chronic GVHD as compared to patients without chronic GVHD (P=0.006 for PFS and P=0.01 for OS). Collectively, these data demonstrate that RIC allo-SCT can mediate a potentially curative graft-versus-myeloma effect with an acceptable incidence of toxicity and TRM.

Determination of chromosome 13 status in bone marrow cells of patients with multiple myeloma using combined morphologic and fluorescence in situ hybridization analysis

Deletion of chromosome 13q is believed to be an adverse prognostic marker in patients with multiple myeloma (MM). Interphase fluorescence in situ hybridization (I-FISH) is the method of choice for detection of chromosome 13q deletion (del13q). However, I-FISH has high false-positive rates attributed to a low percentage of plasma cells (PC), which are responsible for MM, in bone marrow (BM) samples from MM patients. In an attempt to overcome this problem, combined morphologic and I-FISH analyses were performed by a unique system that allows rapid automatic scanning of a large number of cells with simultaneous determination of the lineage of specific cells carrying del13q. The percentage of PC with del13q in BM samples from 40 MM patients was calculated. In addition, we established a useful prognostic ratio defined as the number of PC with del13q divided by the number of non-PC with del13q (PDP/PDNP), which may help to precisely define the putative role of del13q in prediction response of MM patients to new therapeutic compounds. We suggest this technique as a novel sensitive and specific method for detection of del13q in a minor PC population of MM patients.

Multiple myeloma

High-dose therapy with stem cell transplantation (SCT) and novel targeted therapies (thalidomide, its more potent analogues, and bortezomib) represent two approaches for overcoming resistance of multiple myeloma (MM) cells to conventional therapies. While it is now clear that dose-intensification improves the outcome in younger patients, long-term remissions are obtained in a minority of patients. Therefore, the impact of novel agents as part of front-line therapy is the objective of ongoing trials. Gene expression profiling (GEP) will help to improve the management of MM not only by identifying prognostic subgroups but also by defining molecular pathways that are associated with these subgroups and that are possible targets for future therapies. In Section I, Dr. John Shaughnessy describes recent data obtained with GEP of CD138-purified plasma cells from patients with MM. His group has already shown that overexpression of the Wnt signaling inhibitor DKK1 by MM plasma cells blocks osteoblast differentiation and contributes to the development of osteolytic bone lesions. Recent data allow identification of four subgroups of MM in which GEP is highly correlated not only with different clinical characteristics and outcome but also with different cytogenetic abnormalities. In addition, abnormal expression of only three genes (RAN, ZHX-2, CHC1L) is associated with rapid relapses. In the context of intensive therapy with tandem autotransplantations, this model appears to be more powerful than current prognostic models based on standard biologic variables and cytogenetics. Understanding why the dysregulation of these three genes is associated with a more aggressive behavior of the disease will help to define new therapeutic strategies. In Section II, Dr. Jean-Luc Harousseau presents recent results achieved with tandem autologous SCT (ASCT) and with reduced intensity conditioning (RIC) allogeneic SCT. ASCT is now considered as the standard of care in patients up to 65 years of age. The IFM (Intergroupe Francophone du Myelome) has recently shown that double ASCT is superior to single ASCT. Current results of three other randomized trials confirm that double ASCT is superior, at least in terms of event-free survival. However, patients with poor prognostic features do poorly even after tandem ASCT. Strategies to further improve the outcome of ASCT include more intensive therapies and the use of novel agents such as thalidomide and immunomodulatory analogs (IMiDs) or bortezomib. Results of allogeneic SCT remain disappointing in MM even with T cell-depleted grafts. Preliminary results of a strategy combining ASCT to reduce tumor burden and RIC allogeneic SCT are encouraging, although the follow-up is still short. However, again, patients with chromosome 13 deletions have poor results with RIC. Longer follow-up of ongoing multicentric studies will help to clarify the indications of RIC. In Section III, Dr. Paul Richardson summarizes current knowledge of novel targeted therapies in MM. A better understanding of interactions between MM cells and bone marrow stromal cells and of the signaling cascades whereby cytokines mediate proliferation, survival, drug resistance and migration of MM cells provide the rationale for testing novel agents in relapsed/refractory MM. Increased angiogenesis coupled with the known anti-angiogenesis activity of thalidomide justified its use in refractory MM. The remarkable responses initially achieved prompted a number of clinical studies in different indications and the development of more potent IMIDs. Among them CC-5013 (Revlimid) has been tested in Phase I/II studies and a randomized Phase III study has just been completed. Blockade of NF-kappa B using the proteasome inhibitor bortezomib (Velcade) may mediate anti-MM activity by inhibiting interleukin (IL)-6 production in stromal cells and other mechanisms of action have been shown in preclinical studies. Based on the promising results of the Phase II trial, a large randomized trial of bortezomib versus dexamethasone has been completed. Studies of bortezomib combined with other drugs are ongoing. Arsenic trioxide has a number of properties showing that it targets MM cells interacting with the microenvironment. Clinical studies are ongoing as well. Other agents in MM have already been or will probably be translated soon from the bench to the bedside.

Treatment of multiple myeloma

Autologous peripheral blood stem cell (PBSC)-supported high-dose melphalan is now considered standard therapy for myeloma, at least for younger patients. The markedly reduced toxicity of allotransplants using nonmyeloablative regimens (mini-allotransplantations) may hold promise for more widely exploiting the well-documented graft-versus-myeloma (GVM) effect. New active drugs include immunomodulatory agents, such as thalidomide and CC-5013 (Revimid; Celgene, Warren, NJ), and the proteasome inhibitor, PS 341 (Velcade; Millenium, Cambridge, MA), all of which not only target myeloma cells directly but also exert an indirect effect by suppressing growth and survival signals elaborated by the bone marrow microenvironment's interaction with myeloma cells. Among the prognostic factors evaluated, cytogenetic abnormalities (CAs), which are present in one third of patients with newly diagnosed disease, identify a particularly poor prognosis subgroup with a median survival not exceeding 2 to 3 years. By contrast, in the absence of CAs, 4-year survival rates of 80% to 90% can be obtained with tandem autotransplantations. Fundamental and clinical research should, therefore, focus on the molecular and biologic mechanisms of treatment failure in the high-risk subgroup.

Long-term follow up of patients with multiple myeloma after high-dose chemotherapy and allogeneic stem cell transplantation

OBJECTIVES

Allogeneic transplantation may offer a curative approach to multiple myeloma (MM). We retrospectively analyzed the outcome of patients with multiple myeloma undergoing allogeneic stem cell transplantation in the context of beta(2) microglobulin and chromosome 13q.

METHODS

All 13 patients with MM, who were referred to our center for allogeneic stem cell transplantation, were evaluated. Median age of patients was 38 yr, eight patients had chemo-sensitive disease, and median time between diagnosis of MM and transplantation was 15 months. Engraftment, acute and chronic graft vs. host disease, response to treatment, disease-free survival, and overall survival were evaluated according to standard criteria.

RESULTS

There was one transplant-related death. Among 12 evaluable patients, seven patients (58%) achieved a complete remission (CR), and four patients (33%) achieved a partial remission. Acute graft vs. host disease occurred in 46% of patients, and chronic graft vs. host disease in 42% of available patients. After a median follow-up of 69.5 months (range, 5-128) nine patients (70%) are still alive, and six of them have remained progression free. Among five patients with low beta(2) microglobulin and normal chromosome 13q, four patients achieved a CR, with CR duration >5 yr in three of them. Among seven patients with elevated ss(2) microglobulin and/or deletion of chromosome 13q, only three CR were observed, with two patients still in CR on days +920 and +161, respectively.

CONCLUSIONS

Allogeneic stem cell transplantation in patients with MM results in promising rates of CR, but durable remissions are predominantly seen in patients with favorable prognostic parameters.

Comparison of Murine Leukemia Virus, Human Immunodeficiency Virus, and Adeno-Associated Virus Vectors for Gene Transfer in Multiple Myeloma: Lentiviral Vectors Demonstrate a Striking Capacity to Transduce Low-Proliferating Primary Tumor Cells

Genetic modification of primary tumor cells by gene transfer is of major interest to study the role of specific genes in the biology of a given malignancy and to modify tumor cells for therapeutic use. Multiple myeloma (MM) is a low-proliferating cancer, with often less than 1% of the cells in the S phase of the cell cycle. As primary myeloma cells are notoriously difficult to transduce, we conducted a comparison of various viral vectors, known to integrate the transgene of interest into the target genome, for their ability to stably promote the expression of an enhanced green fluorescent protein (EGFP) transgene. We compared three murine leukemia virus-based vectors, differing only in their viral envelope, a human immunodeficiency virus (HIV)-based vector pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G), and an adeno-associated virus type 2 vector. Transduction characteristics of these vectors were evaluated in human myeloma cell lines and in primary myeloma cells. Unequivocally, we observed that the VSV-G/HIV vector was the most efficient vector for transducing the cell lines and the only one able to transduce primary myeloma cells reproducibly. The mean percentage of transduced primary myeloma cells was 43.6% (range, 16.3-77.6%), with one round of infection at a low multiplicity of infection, including MM cell samples with less than 1% of cells in the S phase. A quantitative polymerase chain reaction assay demonstrated that this more efficient EGFP expression was associated with a higher GFP copy number in the targeted cell. We propose that lentiviral vectors should be used for transduction of nonproliferating primary tumor cells such as myeloma cells.

The outcome of unrelated donor stem cell transplantation for patients with multiple myeloma

We performed a retrospective analysis of outcome in 45 patients with multiple myeloma receiving unrelated donor stem cell transplants (UD-SCT) in the UK between 1993 and 2002; 17 received myeloablative conditioning regimens and 28 received reduced intensity conditioning (RIC) protocols. Forty patients received pretransplant CAMPATH serotherapy. Forty-two of 45 patients had detectable disease at transplant, but 33 of 45 were chemoresponsive. Sixty per cent of patients had received a previous autograft. Myeloid engraftment was seen in 95% of recipients and was significantly faster in recipients receiving peripheral blood stem cells (P = 0.07) and RIC (P = 0.001). The incidence of severe (grade 3/4) acute graft versus host disease (aGvHD) was 5% (2/40). The 100-d non-relapse mortality was 18% (5/38) following RIC and 53% (9/17) following myeloablative regimens. Twenty-nine per cent of patients achieved a complete remission, 61% a partial remission, giving a 90% overall response rate. At median follow-up (513 d), overall survival was 40%: 54% in the RIC group (median follow-up: 489 d) and 18% in the myeloablative group (median follow-up: 560 d). In recipients of UD-SCT, RIC protocols that incorporated CAMPATH were associated with faster myeloid engraftment, less severe aGvHD and lower 100-d non-relapse mortality than myeloablative regimens, without a corresponding rise in relapse rate during the period of observation.

Rapid induction of complete donor chimerism by the use of a reduced-intensity conditioning regimen composed of fludarabine and melphalan in allogeneic stem cell transplantation for metastatic solid tumors

We evaluated the feasibility and efficacy of a reduced-intensity conditioning (RIC) regimen of fludarabine and melphalan to achieve rapid complete donor chimerism after allogeneic stem cell transplantation (SCT) in patients with metastatic solid tumors. Between January 1999 and January 2003, 8 patients with metastatic breast cancer (BC) and 15 with metastatic renal cell carcinoma (RCC) underwent allogeneic SCT after an RIC regimen of 5 days of fludarabine and 2 days of melphalan. Filgrastim-mobilized stem cells from HLA-identical related or unrelated donors were infused. Prophylaxis for graft-versus-host disease (GVHD) consisted of tacrolimus and methotrexate. All 22 evaluable patients had 100% donor chimerism at day 30 and at all measurement times thereafter. One patient died 19 days after SCT. Nine patients (39%) had grades II to IV acute GVHD and 10 patients (43%) had chronic GVHD. Five patients (22%) died of nonrelapse treatment-related complications. Treatment-related disease response was seen in 10 patients (45%), with 3 complete responses, 2 partial responses, and 5 minor responses. Fludarabine-melphalan is a feasible and effective RIC regimen for allogeneic SCT in metastatic BC and RCC. It induces rapid complete donor chimerism without the need for donor lymphocyte infusion. Tumor regression associated with GVHD is consistent with graft-versus-tumor effect.

T- and B-cell immune reconstitution and clinical outcome in patients with multiple myeloma receiving T-cell-depleted, reduced-intensity allogeneic stem cell transplantation with an alemtuzumab-containing conditioning regimen followed by escalated donor ly

Immune reconstitution after conventional allogeneic transplantation is a major determinant of survival. We conducted a detailed investigation of T- and B-cell immune reconstitution and clinical outcome in 19 patients with multiple myeloma undergoing reduced-intensity stem cell transplantation using in vivo T-cell depletion with alemtuzumab. These patients experienced delayed T-cell recovery, particularly in the naïve (CD45 RA+) CD4 compartment. T-cell receptor spectratype analysis showed a reduced repertoire diversity, which improved rapidly after the administration of donor leucocyte infusions and subsequent conversion to full donor T-cell chimaerism. Post-transplant recovery of CD19+ B cells was also delayed for up to 18 months. Spectratype analysis of IgH CDR3 repertoire revealed a gradual normalization in IgM spectratype complexity by 6-12 months after transplant. There was a high incidence of viral infection, particularly cytomegalovirus reactivation, but the regimen-related mortality was low, perhaps because of the very low incidence of acute graft-versus-host disease (GVHD; grade I-II skin GVHD was seen in 5/19 patients). Over 80% of all patients have relapsed at a median of 283 (range 153-895) d after transplant, suggesting that the initially low rate of GVHD comes at a high price with regard to the desired graft-versus-myeloma effect.

Allografting with nonmyeloablative conditioning following cytoreductive autografts for the treatment of patients with multiple myeloma

The full potential of a graft-versus-myeloma effect after allogeneic hematopoietic cell transplantation (HCT) for patients with multiple myeloma (MM) has not been realized because of excessive early transplantation-related mortality (TRM) with conventional HCT. Autologous HCTs have been characterized by almost universal disease recurrences. The current trial combined autologous HCT with subsequent nonmyeloablative allogeneic HCT to maintain the benefits of both approaches with acceptable toxicity. Fifty-four patients, 52 years of age (median; range, 29-71 years), with previously treated stage II or III MM (52% refractory or relapsed disease) were given melphalan 200 mg/m2 and autologous HC transplants. Regimen-related toxicities after autologous HCT were moderate with a median of 6 days of neutropenia, 7 days of hospitalization, and 1 death from infection. Forty to 229 days later (median, 62 days), 52 patients received a single fraction dose of 2 Gy total body irradiation and HC transplants from HLA-identical siblings with postgrafting immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP). Patients experienced medians of 0 days of hospitalization, neutropenia, and thrombocytopenia. Sustained engraftment was uniform. With a median follow-up of 552 days after allografting, overall survival is 78%. One patient (2%) died before day 100 from disease progression. Thirty-eight percent of patients developed acute graft-versus-host disease (GVHD; grade II in all but 4 cases) and 46% chronic GVHD requiring therapy. Tumor responses occurred slowly. Thus far, 57% of patients have achieved complete remissions and 26% have achieved partial remissions for an overall response of 83%. Despite being evaluated in elderly patients with MM, this 2-step approach has reduced the acute toxicities of allogeneic HCT while achieving potent antitumor activities.

Low-dose total body irradiation, fludarabine, and antithymocyte globulin conditioning for nonmyeloablative allogeneic transplantation

Nonmyeloablative allogeneic peripheral blood progenitor cell transplantation with low-dose total body irradiation (TBI; 200 cGy) plus fludarabine followed by cyclosporine and mycophenolate mofetil results in modest graft rejection rates. Acute and chronic graft-versus-host diseases (GVHD) are also seen and may not differ substantially from those that occur after fully ablative transplantation. Adding antithymocyte globulin (ATG) to pretransplant conditioning produces substantial immunosuppression. Because of its persistence in the circulation, ATG can achieve in vivo T-cell depletion. Twenty-five patients who were not eligible for conventional fully ablative allogeneic stem cell transplantation by virtue of age or comorbidities underwent nonmyeloablative allogeneic transplantation with ATG 15 mg/kg/d days -4 to -1, TBI 200 cGy on a single fraction on day -5, and fludarabine 30 mg/m(2)/d on days -4 to -2. Oral mycophenolate mofetil 15 mg/kg every 12 hours and cyclosporine 6 mg/kg every 12 hours were started on day -5. Grafts were unmanipulated peripheral blood progenitor cells mobilized with filgrastim 10 microg/kg/d and collected on day 5. The median age of the recipients was 57 years (range, 30-67 years); diagnoses were non-Hodgkin lymphoma (n = 11), acute myeloid leukemia (n = 6), multiple myeloma (n = 3), acute lymphoblastic leukemia (n = 2), severe aplastic anemia (n = 1), paroxysmal nocturnal hemoglobinuria (n = 1), and myelodysplastic syndrome (n = 1). The median CD34(+) and CD3(+) contents of the grafts were 7.6 x 10(6)/kg and 1.6 x 10(8)/kg, respectively. Five patients received voluntary unrelated donor grafts. Three patients, 2 with voluntary unrelated donor grafts and 1 with a sib donor, received a 1 antigen-mismatched graft. The rest were fully matched. Twenty-two of 25 patients were evaluable for chimerism. Sixteen had >/=95% donor chimerism. Four patients displayed 80% to 90% donor chimerism, 1 displayed 78%, and 1 displayed 64%. Eleven patients relapsed with their original disease. One patient rejected the graft at 180 days. The median hospital stay was 27 days. Complications included GVHD in 6 patients (3 patients had grade I or II GVHD of skin and liver, and 3 patients had grade III or IV GVHD of liver and gut). Two of the patients with GVHD had mismatched grafts. Transplant-related toxicity was seen in 4 patients and infection in 5 patients. The median length of follow-up was 162 days (range, 17-854 days). Complete remissions were seen in 10 patients. Four patients remained in complete response (CR) at 280 to 595 days. One patient relapsed with non-Hodgkin lymphoma after a CR of 728 days. Of the 25 patients, 16 died (6 of relapsed disease, 4 of GVHD, 3 of infection, and 3 of transplant-related toxicity) and 9 are alive (6 with CR-2 of them after donor leukocyte infusion-and 3 with relapsed disease). The addition of ATG to low-dose TBI and fludarabine nonmyeloablative conditioning was well tolerated and resulted in >80% donor engraftment in this small cohort. As in other series of truly nonmyeloablative transplantation, a high rate of relapse was observed. Donor engraftment may be facilitated by the addition of ATG to low-dose TBI and fludarabine conditioning.

Treatment of relapsed and refractory multiple myeloma

The definition of relapsed and refractory myeloma was straightforward when melphalan-prednisone constituted the mainstay of treatment and high-dose therapy with transplantation was rarely used in myeloma. However, several advances have occurred in the treatment of myeloma over the past decade. Most notably, high-dose therapy and transplantation have become broadly applicable, thalidomide has become available as effective salvage therapy, and several investigational agents with novel mechanisms of action appear to be very promising. Because of the differing properties of some of these agents, it is often possible to control the disease with an alternative treatment approach after the failure of one therapy. Some data indicate that combinations of these agents work when the drugs have failed individually. Therefore, refractory myeloma indicates disease unresponsive to the most recent therapy administered. Broadly, the salvage approaches that are used in patients with refractory or relapsed disease include high-dose dexamethasone, high-dose chemotherapy with autotransplantation, allogeneic hematopoietic stem cell transplantation, thalidomide-based therapies, and novel/investigational agents. The appropriate therapy for a given situation depends on the nature of the disease, age, organ function, bone marrow function, prior treatment, the availability of stem cell donors, and access to novel agents. A therapeutic trial of thalidomide is essential at some stage of the disease in all patients. High-dose therapy with autotransplantation is needed at some stage of the disease in most patients younger than 65 to 70 years.

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.

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.

Advances in Biology and Therapy of Multiple Myeloma

Even during this past year, further advances have been made in understanding the molecular genetics of the disease, the mechanisms involved in the generation of myeloma-associated bone disease and elucidation of critical signaling pathways as therapeutic targets. New agents (thalidomide, Revimid, Velcade) providing effective salvage therapy for end-stage myeloma, have broadened the therapeutic armamentarium markedly.

As evidenced in Section I by Drs. Kuehl and Bergsagel, five recurrent primary translocations resulting from errors in IgH switch recombination during B-cell development in germinal centers involve 11q13 (cyclin D1), 4p16.3 (FGFR3 and MMSET), 6p21 (cyclin D3), 16q23 (c-maf), and 20q11 (mafB), which account for about 40% of all myeloma tumors.

Based on gene expression profiling data from two laboratories, the authors propose 5 multiple myeloma (MM) subtypes defined by the expression of translocation oncogenes and cyclins (TC molecular classification of MM) with different prognostic implications. In Section II, Drs. Barillé-Nion and Bataille review new insights into osteoclast activation through the RANK Ligand/OPG and MIP-1 chemokine axes and osteoblast inactivation in the context of recent data on DKK1. The observation that myeloma cells enhance the formation of osteoclasts whose activity or products, in turn, are essential for the survival and growth of myeloma cells forms the basis for a new treatment paradigm aimed at reducing the RANKL/OPG ratio by treatment with RANKL inhibitors and/or MIP inhibitors.

In Section III, Dr. Fenton reviews apoptotic pathways as they relate to MM therapy. Defects in the mitochrondrial intrinsic pathway result from imbalances in expression levels of Bcl-2, Bcl-XL and Mcl-1. Mcl-1 is a candidate target gene for rapid induction of apoptosis by flavoperidol. Antisense oglionucleotides (ASO) lead to the rapid induction of caspace activity and apoptosis, which was potentiated by dexamethasone. Similar clinical trials with Bcl-2 ASO molecules alone and in combination with doxorubicin and dexamethasone or thalidomide showed promising results.

The extrinsic pathway can be activated upon binding of the ligand TRAIL. OPG, released by osteoblasts and other stromal cells, can act as a decoy receptor for TRAIL, thereby blocking its apoptosis-inducing activity. MM cells inhibit OPG release by stromal cells, thereby promoting osteoclast activation and lytic bone disease (by enhancing RANKL availability) while at the same time exposing themselves to higher levels of ambient TRAIL. Thus, as a recurring theme, the relative levels of pro- versus anti-apoptotic molecules that act in a cell autonomous manner or in the milieu of the bone marrow microenvironment determine the outcome of potentially lethal signals.

In Section IV, Dr. Barlogie and colleagues review data on single and tandem autotransplants for newly diagnosed myeloma. CR rates of 60%–70% can be reached with tandem transplants extending median survival to ~7 years. Dose adjustments of melphalan in the setting of renal failure and age &gt; 70 may be required to reduce mucositis and other toxicities in such patients, especially in the context of amyloidosis with cardiac involvement.

In Total Therapy II the Arkansas group is evaluating the role of added thalidomide in a randomized trial design. While data are still blinded as to the contribution of thalidomide, the overriding adverse importance of cytogenetic abnormalities, previously reported for Total Therapy I, also pertain to this successor trial. In these two-thirds of patients without cytogenetic abnormalities, Total Therapy II effected a doubling of the 4-year EFS estimate from 37% to 75% (P &lt; .0001) and increased the 4-year OS estimate from 63% to 84% (P = .0009).

The well-documented graft-vs-MM effect of allotransplants can be more safely examined in the context of non-myeloablative regimens, applied as consolidation after a single autologous transplant with melphalan 200 mg/m2, have been found to be much better tolerated than standard myeloablative conditioning regimens and yielding promising results even in the high-risk entity of MM with cytogenetic abnormalities.

For previously treated patients, the thalidomide congener Revimid and the proteasome inhibitor Velcade both are active in advanced and refractory MM (~30% PR).

Gene expression profiling (GEP) has unraveled distinct MM subtypes with different response and survival expectations, can distinguish the presence of or future development of bone disease, and, through serial investigations, can elucidate mechanisms of actions of new agents also in the context of the bone marrow microenvironment. By providing prognostically relevant distinction of MM subgroups, GEP should aid in the development of individualized treatment for MM.