Allogeneic hematopoietic cell transplantation for multiple myeloma

Multiple myeloma: a paradigm for translation of the cancer stem cell hypothesis

Despite recent advances in drug development, multiple myeloma (MM) remains incurable for the majority of patients due to relapse and disease progression. The cancer stem cell (CSC) hypothesis may provide an explanation for these clinical findings. It suggests that the long-term proliferative potential responsible for disease initiation, maintenance, and relapse is contained within specific subpopulations of biologically distinct tumor cells. Data in MM suggest that CSCs represent a rare cell population phenotypically resembling normal memory B cells. Compared to MM plasma cells, MM CSCs also appear to be relatively resistant to a wide variety of standard anti-cancer agents suggesting they may persist following treatment and mediate tumor re-growth and relapse. A unique property CSCs share with their normal counterparts is the potential for self-renewal that likely maintains the malignant clone over time. The development of therapeutic strategies targeting the signaling elements contributing to cancer cell self-renewal has been limited primarily because the cellular processes involved are poorly understood. However, it is common that the signaling pathway components regulating normal stem cell self-renewal are aberrantly activated in human cancers and may serve as potential therapeutic targets. One class of shared regulatory pathways are those active during normal embryonic patterning and organ formation such as Hedgehog (Hh), Notch and Wingless (Wnt), and emerging data suggest that these may play a role in CSCs. Here we review the identification and characterization of MM CSCs, the role of Hh in MM, and issues to be considered during the early clinical testing of CSC targeting agents.

Staged heart transplantation and chemotherapy as a treatment option in patients with severe cardiac light-chain amyloidosis

AIMS

The prognosis of advanced cardiac light-chain amyloidosis is poor. Heart transplantation might enable causative therapy and ultimately improve prognosis.

METHODS AND RESULTS

Nineteen patients with cardiac amyloidosis but no obvious involvement of other organs were scheduled for heart transplantation. Four to 6 months later, high-dose melphalan chemotherapy and autologous stem cell transplantation (HDM-ASCT) was planned in patients not in complete remission. Seven of nineteen patients died while waiting for heart transplantation. The remaining 12 patients (complete remission, n = 4) underwent surgery. Chemotherapy in patients not in complete remission consisted of HDM-ASCT (n = 5/12; subsequent complete remission, n = 2; partial remission, n = 3) or melphalan-prednisolone (partial remission, n = 1). Two of twelve patients were ineligible for any chemotherapy. Three of twelve patients died [423.5 (105-2131) days] from progressive disease, relapse, or sepsis. The 1- and 3-year survival rates were 83 and 83%, respectively, similar to those of patients undergoing heart transplantation for standard indications. Corresponding survival rates stratified by haematological response were 100 and 100% for complete remission (partial remission, 100 and 100%; progressive disease, 0 and 0%).

CONCLUSION

Heart transplantation in advanced cardiac amyloidosis is a promising approach to interrupting the vicious circle of ineligibility for potential curative chemotherapeutic treatment and extremely poor prognosis of cardiac amyloidosis without chemotherapy. Highly urgent heart transplantation combined with subsequent HDM-ASCT appears to offer a successful treatment option to improve the poor outcome of cardiac amyloidosis. However, it should be restricted to highly selected patients in specialized centres.

Multiple myeloma cancer stem cells

Multiple myeloma is characterized by the clonal expansion of neoplastic plasma cells within the bone marrow, elevated serum immunoglobulin, and osteolytic bone disease. The disease is highly responsive to a wide variety of anticancer treatments including conventional cytotoxic chemotherapy, corticosteroids, radiation therapy, and a growing number of agents with novel mechanisms of action. However, few if any patients are cured with these modalities and relapse remains a critical issue. A better understanding of clonogenic multiple myeloma cells is essential to ultimately improving long-term outcomes, but the nature of the cells responsible for myeloma regrowth and disease relapse is unclear. We review evidence that functional heterogeneity exists in multiple myeloma and discuss potential strategies and clinical implications of the stem-cell model of cancer in this disease.

Current status of stem cell transplantation for multiple myeloma

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

The Generation and Anti-Myeloma Activity of a Chimeric Anti-CD54 Antibody, cUV3

Despite new treatment options, including autologous and allogeneic stem cell transplants, multiple myeloma remains an incurable disease. The authors developed and characterized a murine anti-human ICAM-1 (CD54) monoclonal antibody, UV3, which is highly effective in SCID mice with advanced human myeloma xenografts (SCID/ARH-77). To improve the effector functions and pharmacokinetic parameters and to reduce its immunogenicity in humans, the authors engineered this monoclonal antibody into a mouse/human IgG1kappa chimeric (c) antibody, cUV3. Following coexpression and purification of the genetically spliced heavy and light chain constructs, the authors compared cUV3 and UV3 in various in vitro assays, including relative cell-binding affinities and effector functions, namely antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. The authors compared their in vivo retention times and biodistribution patterns in normal mice. In each assay, the authors found that cUV3 was essentially equivalent to UV3. Finally, these antibodies were tested in a SCID/ARH-77 model of advanced myeloma, with daily treatments of 4 mug/g for 4 consecutive days commencing 14 days after tumor cell inoculation. cUV3 was at least as effective as UV3; 40% and 20% of the mice, respectively, were cured, with no sign of disease at day 150. The authors intend to evaluate the efficacy of cUV3 further in SCID/ARH-77 mice using other doses and dosing schedules to try to improve the cure rate. Eventually, they hope to test the efficacy of cUV3 in patients with multiple myeloma.

Treosulfan is an effective inducer of cell death in myeloma cell lines and primary myeloma cells from patients

Multiple myeloma is a non-curable haematological disease involving transformed plasma cells. High rates of complete remission can be achieved with autologous peripheral blood stem cell transplantation. Treosulfan is an alkylating substance that has been used in the treatment of ovarian carcinomas for many years. It has a favourable side-effect profile even at high-dose protocols. Thus, the objective of this study was to evaluate the effect of treosulfan on myeloma cells. The treatment of the myeloma cell lines, NCI-H929 and U266, with treosulfan led to apoptosis in both cell lines in a dose- and time-dependent manner. The induction of apoptosis was accompanied by cleavage of caspases -3 and -9 as well as downregulation of the antiapoptotic protein Mcl-1 and upregulation of the inhibitor of cyclin-dependent kinases, p21WAF1/CIP1. Furthermore, 100 micro mol/l treosulfan was capable of inducing cell death in 63.6 +/- 23.9% of primary myeloma cells, whereas treatment with the same concentration of melphalan showed 59.7 +/- 26% cell death. These in vitro concentrations were at least 10-fold lower than achievable plasma levels, even at conventional doses of treosulfan. Our results suggest that treosulfan might be an appropriate candidate for novel treatment protocols for patients with multiple myeloma.

Multiple myeloma and its treatment

Mr. F received several different treatment regimens for MM. He required a cardioprotectant, dexrazoxane, to continue treatment with the VAD regimen. He received interferon, high-dose chemotherapy with tandem stem cell transplants, and newer agents used in the treatment of MM, such as thalidomide and topotecan. However, as illustrated by Mr. F's case study, MM remains an incurable disease despite advances in its treatment.

Non-myeloablative transplantation

The concept of utilizing enhanced immunosuppression rather than myeloablative cytotoxic conditioning has allowed the engraftment of allogeneic stem cells from related and unrelated donors with lower early transplant-related mortality (TRM) and morbidity. This approach shifts tumor eradication to the graft-vs-host immune response directed against minor histocompatibility antigens expressed on tumor cells. This is not without risk, as the long-term effects of graft-versus-host disease (GVHD), it's treatment, or resulting complications and immunodeficiency may be life threatening. However, this approach does allow the application of a potentially curative procedure to elderly or medically infirm patients who would not tolerate high-dose conditioning regimens. Section I, by Dr. Sandmaier, describes the current use of nonmyeloablative regimens and matched related or unrelated donors for the treatment of patients with CLL, CML, acute leukemia, MDS, lymphoma, and myeloma. In Section II, Dr. Maloney discusses the use of cytoreductive autologous followed by planned non-myeloablative allografts as treatment for patients with myeloma or NHL. This tandem transplant approach has a lower TRM than conventional high dose allografting. The nonmyeloablative allograft may allow the graft-versus-tumor (GVT) immune response to eradicate the minimal residual disease that causes nearly all patients with low-grade NHL or myeloma to relapse following autologous transplantation. In Section III, Dr. Mackinnon discusses the risks and benefits of T cell depletion strategies to prevent acute GVHD, while retaining GVT activity by planned donor lymphocyte infusions. Finally, in Section IV, Dr. Shizuru discusses the relationship between GVHD and GVT activity. Future studies, employing a greater understanding of these issues and the separation of GVHD from GVT activity by immunization or T cell cloning, may allow nonmyeloablative allogeneic transplantation to be safer and more effective.