Dr. Madhav Dhodapkar opened the session providing an overview of research conducted by his research group over the last year. Topics they are exploring include: patient variability of the immune system, manipulations of the immune system, non-immune effects of immune cells, and cell targets of novel therapies. Phase 1 trial data exploring whether natural killer T (NKT) cells could be reliably and specifically manipulated in patients shows that it is possible to expand the number of NKT cells in patients. These cells mediate activation of T cell immunity by a third party dendritic cell (DC) in vivo. The question of how to maintain the expansion of NKT cells in patients by vaccines is being explored. Notably, NKT cells in patients with MM do not work as well as NKT cells from healthy individuals. Dr. Dhodapkar also looked at the potential targets of drugs on T/NKT cells. Revlimid boosts antigen dependent activation and expansion of specific NKT cells. Tumor DC interactions inhibit dexamethasone induced suppression of myeloma. Myeloma cells were thought to be more sensitive to bortezomib (velcade) however DC were shown to be equally sensitive to velcade as myeloma cells. Dr. Dhodapkar suggested that effective suppression of myeloma requires that myeloma cells and DC be targeted by velcade. Some conclusions from this research were that there is a loss of immune effector function in both innate and adaptive lymphocytes with tumor progression and that interactions between cells in the microenvironment may be involved in drug resistance or may be targets for proteasome-targeted drugs. Future research may address tumor specificity or prevention.
Dr. Bjarne Bogen addressed the question of how T cells reject tumors. MM cells have antigenic determinants referred to as idiotypes (Id) which induce specific antibodies and specific T cells. Considering the arms of anti-Id immunity that may have an effect on MM tumor cells, CD4+ T cells were the focus of this presentation. There may be a need for Id+ myeloma protein to prime antigen presenting cells (APC) and to activate Id-specific CD4+ cells. Using a mouse model (MOPC315 plasmacytoma) and a matrigel model, tumor specific CD4+ T cells were shown to become activated and migratory. Dr. Bogen concluded that Id-specific CD4+ cells protect against MM disease in the bone marrow.
Dr. Derek Hart reviewed DC biology in MM then presented some research updates. DC subsets have different paths of development and migration and thus different functions. Although there may be a common DC precursor, 5 exclusive subsets of DC exist in the blood. The main subsets are CD1C and CD16 populations. DC function to link the innate immune system with the adaptive immune system by processing and presenting antigens to the immune system. In MM, DC cells function abnormally. Dr. Hart suggested that cancer vaccination program is reasonable based on research results. Also, the development of monoclonal antibodies developed in the blood of patients is reasonable compared with the challenges of in vitro manufacturing. Preclinical studies generated data showing the effectiveness of blood generated DC and the ability of these cells to have a cytotoxic effect on T cells.
Dr. Massimo Massaia introduced the topic of phenotypic and functional alterations of gamma/delta T cells in myeloma. Tumor progression is due to intrinsic features of the tumor, to the tumor microenvironment, and to an angiogenic switch. The immune system is another factor. Clinically, switching of the immune system affects the health status of the patient but also impacts the status of the tumor. Experiments showed that MM patients have an abnormal distribution of specific T cells (gamma/delta) which could be activated by bisphosphonates via the mevalonate pathway. The immunosensitivity of myeloma cells to these T cells is enhanced by bisphosphonates. In the future, the association of these factors with disease evolution and the potential for mevalonante pathway to be a target for immune recognition may be explored.
Dr. Reiner Raymakers presented data showing allogeneic transplantation in MM patients who received preemptive DLI resulted in better outcomes and durable responses. The data suggest that DLI can be effective if instituted early after T cell depletion transplantation; non-T cell depleted transplantation and reduced-intensity transplantations are less effective strategies. Allogeneic T cell response after HLA-matched stem-cell transplant (SCT) results in graft versus tumor (GVT), graft versus marrow (GVM), and graft versus host disease (GVHD) responses. Results of studies suggest that a clinically feasible study is a host DC vaccination in MM patients following mini-allogeneic SCT. Dr. Raymakers suggested that if transplant does not result in a GVHD effect and if DCs are of non-donor origin, DLI alone will be ineffective to induce GVHD and GVM. Study results showed that in vitro recipient DC but not donor DC are capable of inducing GVHD/GVM while recipient DC are superior in generating responses. In the future, the possibility of recipient DC but not donor DC to induce GVHD/GVM effect needs to be proven. Results of the studies presented here show that it is feasible to generate DC from frozen PBMC.
Dr. Mohamad Hussein opened this interesting session with his presentation on the Phase 1, multi-dose study of SGN-40 (antihuCD40 MAB) in patients with refractory or recurrent MM. SGN-40 is a fully humanized monoclonal antibody (MAB) in the tumor necrosis factor (TNF) receptor family. CD40 ligand is expressed on T cells, B-cells, and dendritic cells. Patients participating in this study had a median time to initial diagnosis of 6.4 years and the median number of prior therapies was 5. Side effects consisted on neutropenia, headaches, and fatigue. Results in 2 patients showed a decrease in B-cells and drop in CD19. At a higher dose, seen in patient 3, there was a 50% reduction of urine protein after just 1 dose. Conclusions from this trial indicate that SGN-40 is safe and well-tolerated with significant antitumor activity.
Dr. Li Long continued the MAB discussion with his presentation on the antagonist Anti-CD40 antibody CHIR-12.12. CD40 is expressed in all types of malignant B cells as well as dendritic cells, monocytes, and macrophages. CD40 in both normal and primary malignant B cells affects cell survival and proliferation. In MM, CD40 is expressed in over 80% of patients in variable levels. CD40 is stimulated by CD40 ligand (L), which prolongs survival of MM cells. CHIR-12 is a fully humanized antibody of IgG1. CHIR-12 potently inhibits CD40 L-induced human B lymphocytic proliferation. Data was shared from a pre-clinical study in a mouse model. CHIR-12 was shown to reduce cell proliferation, and induce cell death. CHIR-12 also exhibited significant anti-myeloma activity in bortezomib-insensitive in the mouse model. Dr. Long noted that CHIR-12 is currently in Phase 1 clinical trial for chronic lymphocytic leukemia (CLL) and a Phase 1 trial for MM is planned for 2005.
Dr. Suzanne Trudel presented on another novel agent, CHIR-258, a multi-targeted tyrosine kinase inhibitor in the treatment of t(4;14) MM. Approximately 15% of patients with MM have a unique t(4;14) translocation, which results in the expression of a receptor tyrosine kinase known as fibroblast growth factor receptor3 (FGFR3). Patients with t(4;14) translocations have a poor prognosis despite use of high-dose chemotherapy highlighting the need for a new therapeutic agent that may improve the clinical outcomes of patients in this subset. Given this information, Dr. Trudels studies hypothesized that the inhibition of FGFR3 kinase activity will prevent tumor formation. CHIR-258 is a potent inhibitor of class III, IV, and V receptor tyrosine kinases (RTK). An in vitro analysis of CHIR-258 in combination with dexamethasone applied to MM cells demonstrated a synergistic interaction. In vivo, CHIR-258 induced tumor regression and inhibited growth of FGFR3 tumors in mouse model. In MM samples from patients with this translocation, CHIR-258 produced cytotoxic responses. She ended her presentation stating a Phase 1 trial will be initiated shortly in the United States and the United Kingdom.
Dr. Helena Jernberg-Wiklund maintained this theme with her discussion on targeting the insulin-like growth factor-1 receptor (IGF-1R) in MM cells. The microenvironment network provides anti-apoptotic and proliferative signals through many molecular pathways. One of these signals is IGF-1R. Using a selective IGF-1R tyrosine kinase inhibitor to target IGF-1R in MM cells, Dr. Wiklund showed a reduction in survival and proliferation. Additionally, the function of critical signaling proteins was affected. In mouse model, survival was increased and tumor load reduced. Clinical trials to be initiated in solid tumors and MM in 2005.
Dr. Noopur Raje followed with a presentation on the in vitro activity of a novel cyclin-dependent kinase inhibitor, CYC202. Cyclins are overexpressed in all MM cells. A dysregulation of cyclin D1-3 occurs in all MM cells making them susceptible to proliferative stimuli. CYC202 (selicicib or R-Roscovitine) is a purine analog that has shown activity in 19 human cancer cell lines and is currently evaluated in ongoing Phase 1 trials. Within 24 hours, CYC202 induces cytotoxicity in MM cells sensitive or resistant to conventional chemotherapy or steroids. Apoptosis is induced in MM cells in a time-and dose-dependent manner. Treatment of MM cells with combination of bortezomib and doxorubicin resulted in synergism. Dr. Raje concluded that these combinations should be further tested in clinical trials.
Dr. Renate Burger offered a presentation on the inhibition of human plasmacytoma cell growth through a novel JAK kinase inhibitor. Protein tyrosine kinases of the JAK family have been associated with cytokine-like hormone receptors and regulate cell proliferation, survival, and differentiation. CB20 is a new small-molecule inhibitor developed and tested in MM cells. Results demonstrated the inhibition of MM cell growth and survival. Drug resistance was also avoided. Blocking these effects may prove to be valuable as a new therapeutic approach.
The final presentation of this session was from Dr. Sagar Lonial, who put forth a presentation on the combination of tipifamib and bortezomib. Because cancer cells are smart, complex, and resistant new treatment options including targeted therapies need to be developed to combat this disease. Based on a hypothesis that combining 2 targeting agents may lead to increased cell death, Dr. Lonial presented results on the combination of tipifamib and bortezomib in MM cell lines. His study showed that MM cells were sensitive to the combination of agents and that apoptosis was time dependent. Dr. Lonial advised that the sequence of administration is critical to achieving optimal response with combined novel agents. In his study, sequential administration produced significantly better results than concurrent administration. He hoped that future clinical trials would take preclinical models into consideration of study design.
Dr. Derek Hart gave an overview of cancer vaccines and the important implications to MM. The goal of vaccine therapy is to manage the disease so that it can be cured by immunotherapy. In MM, the immune system is failing on multiple fronts (DC, T, NK, NKT cells) and so regulatory cells can be considered as problems or as targets for therapy. DC vaccination is developing as an option with DC being harvested from patients, modified, and then administered to patients as the vaccine. The vaccines are effective; patients survive with long term control of disease and the cytotoxic responses seen correlate with clinical outcomes. Another therapy under development is DC immunotherapy for plasma cells. It may be possible to combine active vaccination with an antibody to CD4+ to achieve disease resolution for patients. Several molecules are at various stages of development and combined immunotherapy or combined immune therapy and chemotherapy should be considered.
Dr. Qing Yi spoke about tumor lysate DC vaccination in multiple myeloma patients. DC‑mediated cross priming is a key step in priming of CD4, CD8, NKT and NK cells. Previous DC vaccination studies were initiated in MM 20 years ago. Less than 50% of patients mounted a response to the antigen in these studies. These data suggested that a better target may be MM tumor cells; these cells could be used to identify antigen to be targeted. Studies demonstrated that MM-specific CTLs were able to kill MM tumor cells but not normal cells, suggesting that the T cells recognized specific antigens on the cells. The strategy for the lysate DC vaccine studies was to use patients with advanced disease since those patients would have sufficient cells to produce the lysate and the vaccine. The lysate DC vaccine was injected intranodally and led to an enlargement of liver nodes. Studies showed that T cells did survive the high-dose therapy portion of the treatment regimen. Clinical outcomes are promising with 1 patient in complete remission thus far and 5 patients recruited. These studies show that it is feasible to combine DC vaccine with high-dose therapy and that specific T cells survive and expand upon vaccination. Future goals are to optimize DC immunotherapy in MM.
Dr. Michael Bishop presented preliminary results of a trial looking at tumor antigen immunization of human allotransplant donors in myeloma. Progression and relapse are significant problems with reduced intensity allogeneic SCT (RIST). The hypothesis for the studies was that vaccination in donors with patient specific idiotype would result in improved remissions. The objective of the trial was to induce cellular and humoral immunity in allogeneic donors and recipients against the unique idiotype expressed by the recipient myeloma. Results of the trials showed that the vaccine was successfully generated from 10 patients. The study included 7 matched siblings who completed vaccination. In terms of safety findings, there was a single grade 3 toxicity observed (lymphopenia that was transient after vaccination). Other safety findings included Grade 1 and 2 toxicities, including reactions at the injection site and systemic bone pain.
Dr. Freda Stevenson presented data about DNA vaccination against MM post-autologous or -allogeneic transplantation. Tumor cells have cell surface glycoproteins, secreted and shed antigens, and MHC class I associated peptides, all which may be targets for immune therapy. For DNA vaccines, there are 2 options to consider: to overcome tolerance issues or to vaccinate a donor who is immunocompetent. To improve uptake (transfection) of the DNA vaccines, electroporation of the vaccine into muscle tissue was tested in a mouse model. Issues to be resolved include determining the immune status of MM patients, the clinical setting where DNA vaccines should be used, and whether MM patients can respond to conventional vaccines. Preliminary results show that MM patients can respond to conventional vaccines. Patients are able to mount an immune response. At 1 year after transplant, patients were responding and recovering so this was considered a reasonable time to administer the DNA vaccine. Studies showed that DNA fusion vaccines are convenient and are an easy way to attack MM tumor cells.
Dr. Nikhil Munshi closed the session with a review of various strategies to load antigens onto DC. His lab has fused DC and MM cells so that the resulting cell would present for antigen development. Notably, the fused DC/MM cells are highly viable and functional in terms of ability to stimulate T-cell proliferation. In a clinical study, 6 patients were treated with fused DC/MM cells and an immune response was observed. Since no serious adverse events were observed, the study is continuing with dose escalation. With only preliminary data available, comments about clinical efficacy cannot be made. Dr. Munshi suggested that novel agents should be identified, and decision about the use of antigens in therapy should be made. Studies need to be conducted to come to an understanding of immune dysregulation in MM. Use of immune-modulating agents may allow immune responses to be augmented while avoiding immunosuppression. In the future, understanding of changes in the immune environment in myeloma may help to identify novel agents that may cure MM.
Dr. Pieter Sonneveld chaired and opened this session with his presentation on drug resistance in MM. Regardless of the advent of new therapeutic options in the treatment of MM, recurring disease is the primary reason for treatment failure. Multiple factors contribute to variations in drug response, such as drug transport, intracellular signaling, unknown genes, cross talk, and the genetic evolution of the tumor. Therefore, a new strategy focusing on tumor targets needs to be employed to manage drug resistance. Dr. Sonneveld reviewed the role of pharmacogenetics in drug metabolism and reiterated that genetic markers are predictive of patient response to chemotherapy. As mentioned in other presentations, activation of specific signaling pathways may induce cell proliferation and induce apoptosis thereby protecting the MM cell from drug-induced cytotoxicity. Other recently developed drugs target the interaction of the MM cell with the bone marrow microenvironment by inhibiting angiogenesis (thalidomide, lenalidomide) or through downregulation of adhesion molecules (bortezomib). Dr. Sonneveld acknowledged that the mechanisms of drug resistance with these new agents are unknown and there are many issues to overcome due to the complexness of drug resistance.
Dr. Laurence Catley presented in place of Dharminder Chauhan on therapeutic implications of anti-apoptotic signaling in MM cells. Defects in apoptotic signaling can lead to the development of drug resistance. In MM, loss of apoptotic response to chemotherapy results from the following reasons: genetic abnormalities, overexpression of anti-apoptotic proteins, MM cell binding to bone marrow and bone marrow stromal cells, and cytokines. Two major stress signaling pathways exist: extrinsic and intrinsic. Studies have shown that bortezomib induces apoptosis in both pathways suggesting that combining biochemical inhibitors of growth/survival signaling pathways with conventional anti-MM agents may enhance cell death. These data provide important information to guide future therapy directed at MM.
Dr. Suzanne Lentzsch provided a discussion on the role of C/EBPß, which belongs to a family of transcription factors. C/EBPß plays an important role in the generation of B lymphocytes. Data suggest that C/EBPß may also play a role in the pathogenesis of MM. Given this information, Dr. Lentzsch analyzed the thalidomide derivative CC-4047 (actimid). Similar to thalidomide, CC-4047 has anti-angiogenic properties, but with less side effects. Treatment with CC-4047 in mice with MM tumors induces complete remission that is sustained over the duration of treatment. Dr. Lentzsch tested CC-4047 in cell lines in order to understand the underlying mechanism of action of resistance and sensitivity. Results showed that protein expression of C/EBPß is downregulated in MM cell lines sensitive to CC-4047. She concluded that CC-4047 inhibits growth and angiogenesis better than thalidomide and that C/EBPß may confer resistance to CC-4047. Future studies will be conducted to better understand resistance.
Dr. Steven Le Gouill concluded the final focus session with a discussion on bortezomib and Mcl-1. As mentioned throughout this session, resistance to novel agents, such as bortezomib, is unknown. Mcl-1 is an antiapoptotic protein that protects MM cells against spontaneous and dexamethasone-induced apoptosis. His study investigated the role of Mcl-1 in bortezomib-induced apoptosis in comparison to conventional therapies doxorubicin and melphalan. His analyses suggest that bortezomib and melphalan, but not doxorubicin, triggers Mcl-1-dependent-induced apoptosis pathways. His study demonstrates that Mcl-1 may be an important mediator of bortezomib and melphalan-induced apoptosis.
For more information regarding these sessions, look for the complete proceedings to be published after the conclusion of this workshop.