We thank Celgene for providing an unrestricted educational grant which made possible these updates from Stockholm.
This is a summary of the events of September 2, 1999 at the VII International Workshop.
The Myeloma Cell Compartment
This session focused on the development of the abnormal plasma cells that are the hallmark of multiple myeloma. Myeloma cells are the end product of a process of differentiation that starts with stem cells in the bone marrow. The immediate precursors of myeloma cells are known as B cells. The different stages in the formation of B cells from stem cells are marked by different proteins, called CD proteins, on the cell surface. By studying CD markers, researchers hope to identify the stage at which the abnormal cells develop, in order to better understand the nature of the disease and to develop strategies for interrupting the process and preventing or curing myeloma.
The following researchers presented data in this session:
- Dr. Andrew Craxton , University of Washington
- Dr. Marleen Bakkus, Free University of Brussels
- Dr. Surinder Sahota, Southamptom University Hospital (UK)
- Dr. Linda M. Pilarski, University of Alberta
- Dr. Thomas Rasmussen, University of Copenhagen
Given the complexity of the material and the lack of availability of copies of the slide presentations, we have not attempted to summarize the disccussions here. For those interested in this area, we would suggest you consult the published work of the presenters.Oncogenic Events in the Pathogenesis of Multiple Myeloma
The role of chromosomal abnormalities in the development of multiple myeloma was the subject of this session. A number of different aberrations affecting plasma cells have been identified, each of which is present in a subset of patients.
- Dr. Riccardo Della-Favera of Columbia University discussed the implications of abnormalities associated with chromosome 1q21. A group of genes associated with this chromosome, MUM (multiple myeloma)-2 and MUM-3, are thought to be involved in normal B cell function and B cell malignancy. Abnormalities of chromosome 1q21 alter the normal function of these genes and are associated with a poor prognosis in patients with multiple myeloma.
- The absence of chromosome 13 is another indicator of a poor prognosis. Dr. Thierry Facon of the Claude Huriez Hôspital (France) reported that an analytic procedure called fluorescence in situ hybridization (FISH) can help to identify a higher-than-expected incidence of chromosome 13 deletions. The presence of elevated levels of a protein called b 2 microglobulin and secretion of the immunoglobulin IgA are additional factors associated with a decreased survival time. Dr. Facon recommended that FISH analysis be performed routinely to identify patients with chromosome 13 deletion.
- Dr. Johannes Drach of the University of Vienna discussed the chromosomal abnormalities in the immunoglobulin disorder, monoclonal gammopathy of undetermined significance (MGUS). MGUS, a condition that has no overt symptoms and requires no treatment often is a precursor to multiple myeloma. Chromosome 13 deletions are among the chromosomal abnormalities present in MGUS and may be associated with a high risk of ultimately developing multiple myeloma.
- Multiple myeloma is a disease involving a variety of chromosomal abnormalities that promote the proliferation of abnormal plasma cells and/or inhibit apoptosis, or cell death, to varying degrees. Dr. Brian van Ness of the University of Minnesota discussed the implications of this genetic heterogeneity, which is present within individual patients at varying disease stages and different tumor sites. Both disease progression and therapeutic response are affected. Since different chemotherapeutic agents affect either proliferation or apoptosis, genetic analysis can be used to optimize drug treatment. In the future, it may also lead to the design of appropriate gene therapy for patients with multiple myeloma.
Interaction of Myeloma Cells with the Bone Marrow Microenvironment
- To conclude the session, Dr. Leif Bergsagel of Cornell University and Dr. Michael Kuehl of the Bethesda Naval Hospital reviewed some of the mechanisms of chromosomal translocation – that is, the transfer of genetic information between unmatched chromosomes – that are thought to initiate the development of abnormal plasma cells. In addition, Dr. Kuehl identified a specific translocation involving the c-myc gene as a key event in the progression of multiple myeloma.
Factors in the microenvironment of the bone marrow that influence the course of multiple myeloma were discussed in this session. By identifying these factors and their specific role in the disease process, researchers will be able to design therapies that counteract those factors associated with disease progression and promote those associated with remission.
- Dr. Joshua Epstein of the Arkansas Cancer Research Center described research indicating that the human bone marrow environment is essential for the growth and survival of myeloma cells. The studies also demonstrated that these cells are incorporated into the stroma, or basic structure of affected bones, and that the effects of the disease on bones result from the interaction of bone tissue and myeloma cells. One approach to the treatment of multiple myeloma is the administration of bisphosphonate drugs (e.g., pamidronate/Aredia®) that change the bone marrow environment and prevent further bone destruction.
- Dr. Federico Caligaris-Cappio of the University of Turin discussed the role of two surface proteins, CD38 and CD31, in relation to the progression of multiple myeloma. CD 38 is a plasma cell protein that influences both the differentiation and proliferation of myeloma cells. CD31 is found on a variety of cells involved in the immune response and promotes adhesion to the cell. The interaction between these cells influences the interactions between proliferation and apoptosis of myeloma cells. Specifically, a high level of CD38 combined with a low level of CD31 is associated with aggressive disease.
- Dr. Benjamin van Camp of the Free University of Brussels described research indicating that the bone marrow microenvironment plays a role in attracting myeloma cells. Studies involving insulin-like growth factor-1 (IGF-1) and the cell surface adhesion protein CD44v6, which is regulated by IGF-1, indicate that the presence of myeloma cells in bone marrow increases the activity of IGF-1 and CD44v6 and thus the migration and binding of these cells into the bone marrow. This effect can be neutralized by blocking the activity of IGF-1.
- The migration of myeloma cells into the blood is increased by laminin, a component of the lining of blood vessels, and by the motility-related protein (MRP-1) also known an CD 9. Dr. Ivan van Riet of the Free University of Brussels discussed studies indicating that the laminin receptor protein 67LR is associated with the development of extramedullary – that is, outside of the bone marrow – tumors (plasmacytomas) in advanced multiple myeloma. In contrast, high levels of MRP-1/CD9 are associated with less aggressive disease.
Control of Growth and Survival of Myeloma Cells
- Dr. Andries Bloem of the University Hospital Utrecht discussed the role of variants of the CD44 protein in multiple myeloma. CD44v10 is associated with stable disease, while CD44v9, which affects the binding of myeloma cells to bone marrow, tonsils and spleen, is associated with progressive disease. Blocking the bonding of CD44v9 inhibited the secretion of interleukin-6 (IL-6), a protein involved in the pathogenesis of multiple myeloma.
Factors involved in the development of myeloma cells in the bone marrow, including the role of the nonspecific cell surface antigen interleukin-6 (IL-6) were the subject of this session.
- Dr. Bernard Klein of INSERUM (France) discussed the role of the protein syndecan-1, or CD138. Syndecan-1 is found both on the cells that constitute normal membranes throughout the body and on all malignant plasma cells, where its function is unknown. However, blood levels of syndecan-1 are higher in patients with multiple myeloma than in healthy individuals. In its purified form, it induces apoptosis in IL-6-dependent myeloma cells in the laboratory but protects these cells from apoptosis in the body
- Dr. Regis Bataille, Institute of Biology (France) discussed the factors, including inappropriate secretion of IL-6, that result differentiate the excessive production of plasma cells from normal plasma cell production in the bone marrow. This phenomenon is known as reactive plasmacytosis and is a key feature of multiple myeloma.
- Studies to elucidate the aberrant behavior of IL-6 that results in the production of myeloma cells rather than normal B cells were described by Dr. Diane K. Jelinek of the Mayo Clinic.
- Dr. William S Dalton of the University of South Florida discussed the mechanisms by which myeloma cells resist apoptosis induced by the surface protein Fas (CD95). This resistance may develop from a Fas mutation, and is directly correlated with the level of resistance to chemotherapy in patients with multiple myeloma.
- Dr. Andrew Belch of the University of Alberta discussed the ability of myeloma B cells to expel chemotherapeutic agents. As a result, a major reservoir of drug resistant cells remains in the body after autologous transfusion – that is, transfusion of bone marrow or stem cells (B cell precursors) from the patient himself. P-gp is a protein that actively transports drugs out of cells and confers resistance to chemotherapy. This effect must be overcome in order to eliminate myeloma cells from the body. The clinical benefit of drugs that circumvent P-gp needs to be confirmed in clinical trials.
- Dr. Pieter Sonneveld of University Hospital Rotterdam described other mechanisms of multidrug resistance (MDR) in multiple myeloma. These include a mutant form of the receptor for glucocorticoid agents (such as dexamethasone), and the major vault protein (MVP), which appears in refractory cases of multiple myeloma.
Sponsored Symposium on Drug Resistance and Reversibiity in Hematological Disorders
- An overview of advances in the biology of multiple myeloma and their potential implications for therapy was presented by Dr. Kenneth Anderson of the Dana Farber Cancer Institute. Increased understanding of the bone marrow microenvironment is especially important in this regard. The recognition that binding of tumor cells to bone marrow cells stimulates IL-6 and related substances, which results in the formation of new blood vessels (angiogenesis), has led to the therapeutic use of thalidomide. This agent inhibits angiogenesis and IL-6 production and has been shown to produce complete or near-complete remission in a number of patients . (Details of one thalidomide study are be provided later in the program.) Other advances include the identification of proteins that affect DNA repair (Ku86) or that may serve as a target on tumor cells (Muc-1). In addition, new strategies for inhibiting myeloma cell growth, overcoming drug resistance and/or triggering apoptosis can be expected to emerge as the processes involved in cell growth and apoptosis are more fully defined. The evolution of new approaches to the treatment of multiple myeloma based on the biology of the disease offers the prospect of more thorough eradication of myeloma cells and improved patient survival.
International experts in this field participated in a symposium sponsored by Novartis Pharma AG and chaired by Professor Hakon Mellstedt of the Karolinska Institute, who introduced the program.
- Dr. Pieter Sonneveld discussed multidrug (MDR) resistance in hematologic malignancies. The membrane protein (P-gp) pumps toxic agents, such as drugs used in chemotherapy, out of cells. P-gp is an important unfavorable prognostic factor in hematologic diseases, including acute the elderly. In many patients, small populations of P-gp-containing cells that are present at diagnosis develop at relapse into a clone, or group of identical cells, that are resistant to chemotherapy. Other membrane pumps have also been identified, but P-gp is at present the only one that is subject to reversal with drug treatment. Cyclosporin A has shown positive effects on drug resistance in patients with relapse of multiple myeloma. A related agent, PSC 833, has produced complete remission and/or improved survival in patients with acute leukemia. Additional trials are needed to optimize its clinical effect and reduce toxicity.
- Dr. Curt Peterson of Linkoping University (Sweden) discussed the problem of drug interactions with MDR-reversing agents. With older drugs such as verapamil, the concentration required to achieve a clinical effect in patients is higher than that used in laboratory experiments. However, P-gp (p-glyco-protein) is found in a variety of normal cells in the liver, kidney, gastrointestinal tract and airways, so it also inhibits the excretion of chemotherapeutic agents from these cells as well from tumor cells, producing extensive toxic effects in normal cells occur at doses that are effective in reversing MDR. Because of this interaction, the dose of the chemotherapeutic drug must be reduced, which may reduce its therapeutic activity. Promising results in a small study with the new P-gp reversing agent, PSC 833 (valdospar) indicate that it may provide clinical benefits. To achieve the full clinical potential of such agents, they should be used at an early stage of therapy, since resistance that develops later may be caused by other mechanisms.
Notes from Parallel Session on Thursday Immune Therapy, Conventional Therapy and New Drugs
- Valspodar (PSC 833) is a potent new compound under development as an anti-MDR drug by Novartis Pharma. Related to the P-gp inhibitor cyclosporin A, valspodar does not suppress the immune system and is not toxic to the kidneys or other normal cells. An overview of the clinical experience in hematological disorders was presented by Dr. Renaud Capdeville of Novartis.
There were four presentations about dendritic cell-based vaccination approaches, Dendritic cells are a component of the immune system that detect and present antigens to the immune system so that it can respond.
- Dr. D.N.J. Hart of Australia presented findings about control of dendritic cell molecular expression. This area of investigation focuses on the interaction of dendritic cells with other cells in the body, with an eye towards understanding how these cells can be used as part of vaccines and other immunotherapy protocols
- Dr. Malcolm McKenzie of the Center for Blood Research presented the results of a trial of dendritic cell vaccine therapy for patients with refractory myeloma (disease which will not respond to standard treatments).. Using a blood-filtering technique call leukapheresis, patients’ dendritic cells were harvested and then trained to recognize the patient’s disease idiotype (fingerprint). Dr. McKenzie stated that idiotype vaccination appears to be safe. Approximately one half of the patients evaluated had increased immune responses after vaccination. 20% had reduced blood protein levels that lasted an average of 8 weeks. All had disease progression before entering the study. Median time time to disease progression was 27 weeks. Further trials are needed to determine appropriate role of this approach.
- Dr. Martha Lacy of the Mayo Clinic presented initial results of trials for dendritic cell vaccination for post-transplant patients. In the myeloma patients treated, there was one complete remission, one near-complete remission and seven stable. In the amyloid patients, the group observed one response, three stable and one death. The group observed an increase in total t-cells an improvement in CD8 counts for a select number of patients.
- Dr. Volker Reichart of Tübingen University presented results of a similar trial with dendritic cell vaccination after transplant. The trial worked with a subset of dendritic cells derived from a type of cells called monocytes. It was possible to harvest the required cells from patients post transplant. The investigators are currently working to identify immune responses (t-cells mobilized) specific to the patients’ tumor (the study is still ongoing).
- Dr. Keith Stockrel-Goldstein of the Stanford University Cancer Center presented results of a trial of dendritic cell vacciation for post transplant multiple myeloma patients. Side effects of the vaccination were mild. 21 of 24 patients developed an anti-KLH rsponse while only three developed an anti-idiotype response. A small number of patients who had residual disease after transplant had some further disease reduction after vaccination.
Other presentations in this session involved discussion of observations about the behavior of dendritic cells and the implication for prognosis and treatment.
- Dr. Douglas Joshua of the Royal Prince Alfred Hospital in Australia presented data showing that there are aberrations in dendritic cells of myeloma patients that may imply that there may be limitations to how well they can serve in vaccine strategies based on using those cells.
- Dr. M. Mitterer of Austria discussed methods of culturing dendritic cells outside of the body, which is a critical step in any vaccine approach based on these cells. Discussion focused on understanding which subtypes of the dendritic cells will grow in culture. The presenter also commented that they were unable to confirm the presence of KSHV viral DNA identified by previous investigators.
- Dr. M. Zeiss of Germany discussed an approach being evaluated at present with a mouse model of adding FLT3 ligand and IL-2 to achieve better anti-myeloma effect in dendritic cell idiotypic vaccination.
Dendritic cell-based vaccination approaches appear to be safe and a promising. The bulk of the investigation on this issue appears to focus on post-transplant vaccination. There remain concerns about how effective the technique will prove to be, given concerns that myeloma patients’ dendritic cells may not be fully functional and questions about whether the immune response can be useful beyond patients with minimal residual disease.Other presentations at the Thursday parallel session included:
- Dr. Brian Durie of the Cedars-Sinai Comprehensive Cancer Center presented findings about the efficacy of low-dose thalidomide in multiple myeloma. Patients were given doses of 50mg, with the dose escalated (up to as much as 400mg) only when the patient failed to respond. He observed 8 responses(24%), 16 who didn’t respond and 9 who could not tolerate the treatment and stopped before completing the minimum eight weeks required for evaluation as part of the study. In those who responded, Dr. Durie observed decreases in M-protein and beta2-microglobulin as well as improvements in hemoglobin. Some drops in whit counts wr also observed. All of the eight responders were kappa sub-types (vs. lambda). Patients who could not tolerate thalidomide included somnolence, tremor, dizziness, fatigue, nausea, bone pain, rash and constipation. Elevation of serum creatinine (indicating declining kidney function) occurred in three patients, which tended to reverse, at least partially, after stopping thalidomide treatment.
- Dr. Mohammed Hussein of the Cleveland Clinic presented data about the use of rituxan, a monoclonal antibody in the treatment of myeloma. This work grew out of research into the causes of relapse in myeloma. In vitro data suggested that anti-CD20 therapy could reverse drug resistance. Rituxan was given to newly diagnosed stage III patients using a protocol established in the treatment of lymphoma and the rituxan was given in combination with melphan-presdnisone therapy. Of 18 patients treated and evaluable, there were 5 responses to the rituxan/melphalan combination, 2 major and 3 minor. 80% of the 5 who responded tested CD20 positive. The investigators concluded that rituxan may have an application in treating myeloma, particularly in patients who test CD20+. 15-20% of the patients treated tested positive for CD20. They observed slightly higher myelosuppression in patients being treated with the combination of rituxan and melphalan versus those treated with melphalan alone.
- Dr. P Moreau of France discussed work being done using anti-IL-6 therapy, in conjunction with high dose melphalan to improve the response rate for high dose melphan. The trial was performed on relapsing patients who had unfavorable prognostic factors, with many heavily pre-treated. The therapy was tolerated well. They observed an 80% response rate, with 11 partial responses, 5 complete responses, The conclusion was that this is a promising approach and a randomized study will be pursued.
- Dr. Mitchell Smith of the Fox Chase Cancer Center discussed a phase II clinical trial of dexamethasone and 13-cis-retinoic acid as a first-line therapy for myeloma. The rationale is that both agents act to reduce IL-6 levels. IL-6 is felt to stimulate growth of myeloma cells. The pulsed dexamethasone regimen of 40mg for four days with a 10 day rest period has historically had a 45% response rate. 2 had complete, 8 partial responses, 4 stable, none had disease progression. The conclusion was that the drug is well-tolerated and may prove to be a valuable approach but that further studies are required.
- Dr. Facon of Hôspital Claude Huriez presented a study comparing dexamethasone(dex) to dex with interferon, melphalan-prednisone(MP) alone, dex in combination with MP in treatment of 457 newly-diagnosed patients aged 65-75 years. The major conclusion was that MP and MP in combination with dex had a significant survival advantage over dex as a single agent treatment. Based on the inferior results of the dex only arms of the trial, the study was terminated. These results are based on a follow-up period of nineteen months. It was suggested that it would be wise to update these results once more time has elapsed.
- Dr. Martin Okin of the Virginia Piper Cancer Institute discussed the results of a trial conducted by the Eastern Cooperative Oncology Group, looking at secondary myelodysplastic syndrome (MDS) and acute myeloblastic leukemia(AML) in multiple myeloma. Patients typically develop these disorders as a consequence of prior treatments and have trouble maintaining their blood counts. The study looked at the incidence of these disorders in 653 patients treated with VBMCP (a combination chemotherapy) alone, with high-dose cyclophosphamide and with interferon. 31 of the 653 patients developed MDS or AML. No one factor emerged (e.g., age, disease stage, etc.) as a predictor of who would develop MDS/AML. There was no significant difference in the frequency of MDS/AML in the different treatment arms. Secondary MDS/AML remains a serious problem. 6% of the 5 year survivors developed MDS or AML. 19% of the 10 year survivors developed the disorders.. With increasing survival of myeloma patients, the risk of these secondary complications increases and needs attention from the scientific community.