Myeloma-reactive allospecific cytotoxic T lymphocytes lyse target cells via the granule exocytosis pathway

Clonal Cytotoxic T Cells in Myeloma

Multiple myeloma (MM) is a malignant disease characterized by accumulation of morphologically recognizable plasma cells producing immunoglobulin (Ig) in the bone marrow. The occurrence of clonal T cells in MM, as defined by the presence of rearrangements in the T-cell receptor (TCR)-beta chains detected on Southern blotting, is associated with an improved prognosis. This review aims to describe the various ways in which we have demonstrated the presence of such T cell clones, and to describe the phenotype of these cells. Finally, the specificities of these clinically important CD8+ T cell populations will be discussed in the context of immunotherapy.

Early recovery of aggressive cytotoxic cells and improved immune resurgence with post-transplant immunotherapy for multiple myeloma

A phase I/II trial evaluated early administration and dose escalation of interleukin (IL)-2 with granulocyte macrophage colony stimulating factor (GM-CSF) post-transplant. Following melphalan (200 mg/m(2)) and an autologous transplant, IL-2 was initiated (day 0) and continued for 4 weeks. GM-CSF (250 mcg/m(2)/day) began on day 5. Fifteen of 19 patients completed therapy. No treatment-related deaths occurred. IL-2 (1 x 10(6) IU/m(2)/day) was not tolerated in two of six patients due to > or =grade 3 fatigue/diarrhea (n=1) or supraventricular tachycardia (n=1). The maximum tolerated dose of IL-2 was 6 x 10(5) IU/m(2)/day; this dose was well tolerated by 11 of 13 patients. Neutrophil and platelet engraftment occurred on day 13 (median; range 10-17 days) and day 13 (median; range 0-74 days), respectively. When compared to control patients, there was a marked increase in the number of CD3+ T cells (P=0.005), CD4+ T cells (P=0.01), CD8+ T cells (P=0.001) and CD4+CD25+Treg cells (P=0.015) post-transplant. Cytotoxicity directed against myeloma cells was markedly increased when compared to control patients (P=0.017). This unique trial design using early administration of IL-2 with GM-CSF during the period of lymphodepletion, demonstrated a marked increase in the number and function of early cytotoxic effector T cells, without suppression of engraftment.

Gamma-radiation upregulates MHC class I/II and ICAM-I molecules in multiple myeloma cell lines and primary tumors

The gamma-irradiation of normal cells causes an increased synthesis of specific proteins. However, few studies have described the effects of high doses of irradiation on the expression of cell surface antigens in tumor cells. This study analyzed the effects of high doses of gamma-irradiation on the surface antigen expression of Major Histocompatability Complex (MHC) class I/II and intercellular adhesion molecule-1 (ICAM-I) in human multiple myeloma (MM) cell lines ARP-1, ARK-RS, and 10 MM primary tumors. The expression of surface antigens was evaluated by fluorescence-activated cell sorter analysis at different time points, following the exposure to high doses of gamma-irradiation. Doses of 10,000 and 15,000 cGy were not sufficient to totally block cell replication in both cell lines and primary tumors; cell replication was able to be inhibited completely only at 18,000 cGy. Lower doses (10,000 cGy) and lethal doses of irradiation (i.e., 15,000 and 18,000 cGy) increased the expression of all surface antigens present on the cells before irradiation. Essentially, such upregulation was shown to be dose dependent, with higher radiation doses resulting in higher antigen expression. Furthermore, when the kinetics of this upregulation were studied 3 and 6 d after irradiation, there was a constant increase in antigen expression in MM cells. These findings suggest that upregulation of costimulatory molecules, such as of MHC class I/II antigens and ICAM-I molecules in MM patients treated by gamma-radiation, can increase the immunogenicity of the tumor cells. In light of these findings, radiotherapy combined with immunotherapy might be considered in relapsing patients after receiving the standard treatment.

Reduction of spontaneous metastases through induction of carbohydrate cross-reactive apoptotic antibodies

The selective targeting of tumor-associated carbohydrate Ags by the induction of serum Abs that trigger apoptosis of tumor cells as a means to reduce circulating tumor cells and micrometastases would be an advantage in cancer vaccine development. Some plant lectins like Griffonia simplicifolia lectin I and wheat germ agglutinin mediate the apoptosis of tumor cells. We investigated the possibility of using these lectins as templates to select peptide mimotopes of tumor-associated carbohydrate Ags as immunogens to generate cross-reactive Abs capable of mediating apoptosis of tumor cells. In this study, we show that immunization with a mimotope selected based on its reactivity with Griffonia simplicifolia lectin I and wheat germ agglutinin induced serum IgM Abs in mice that mediated the apoptosis of murine 4T1 and human MCF7 cell lines in vitro, paralleling the apoptotic activity of the lectins. Vaccine-induced anti-carbohydrate Abs reduced the outgrowth of micrometastases in the 4T1 spontaneous tumor model, significantly increasing survival time of tumor-bearing animals. This finding parallels suggestions that carbohydrate-reactive IgM with apoptotic activity may have merit in the adjuvant setting if the right carbohydrate-associated targets are identified.

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.

Beta 2-microglobulin as a negative regulator of the immune system: high concentrations of the protein inhibit in vitro generation of functional dendritic cells

Two common features in human immunodeficiency virus infection and acquired immunodeficiency syndrome, rheumatoid arthritis, and hematologic malignancies including multiple myeloma are elevated serum levels of beta(2)-microglobulin (beta(2)M) and activation or inhibition of the immune system. We hypothesized that beta(2)M at high concentrations may have a negative impact on the immune system. In this study, we examined the effects of beta(2)M on monocyte-derived dendritic cells (MoDCs). The addition of beta(2)M (more than 10 microg/mL) to the cultures reduced cell yield, inhibited the up-regulation of surface expression of human histocompatibility leukocyte antigen (HLA)-ABC, CD1a, and CD80, diminished their ability to activate T cells, and compromised generation of the type-1 T-cell response induced in allogeneic mixed-lymphocyte reaction. Compared with control MoDCs, beta(2)M-treated cells produced more interleukin-6 (IL-6), IL-8, and IL-10. beta(2)M-treated cells expressed significantly fewer surface CD83, HLA-ABC, costimulatory molecules, and adhesion molecules and were less potent at stimulating allospecific T cells after an additional 48-hour culture in the presence of tumor necrosis factor-alpha and IL-1beta. During cell culture, beta(2)M down-regulated the expression of phosphorylated mitogen-activated protein (MAP) kinases, extracellular signal-related kinase (ERK), and mitogen-induced extracellular kinase (MEK), inhibited nuclear factor-kappaB (NF-kappaB), and activated signal transducer and activator of transcription-3 (STAT3) in treated cells, all of which are involved in cell differentiation and proliferation. Thus, our study demonstrates that beta(2)M at high concentrations retards the generation of MoDCs, which may involve down-regulation of major histocompatibility complex class I molecules, inactivation of Raf/MEK/ERK cascade and NF-kappaB, and activation of STAT3, and it merits further study to elucidate the underlying mechanisms.

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

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

T cells in myeloma

The current trend to develop immunotherapy strategies for patients with myeloma and other B cell malignancies has stimulated considerable interest in the functional state of the T cell population in these patients. Expanded clones of T cells exist in many patients with myeloma and their presence is associated with an improved survival. However, isolating T cells with tumour specificity has proven to be a difficult task and clinical immunization trials have so far failed to achieve a significant response. There is now evidence that tumour specific T cells are either tolerized or deleted following antigen presentation and that idiotype-derived, immunodominant tumour peptides may not exist in all patients. In order to develop more effective immunotherapy strategies for patients with myeloma, further studies are urgently required to identify the most appropriate tumour antigen, the nature of the interactions which take place during antigen presentation, and how to promote the cytotoxicity of autologous T cells.

GM-CSF and IL-12 production by malignant plasma cells promotes cell-mediated immune responses against monoclonal Ig determinants in a light chain myeloma model

Immune responses towards malignant plasma cells have clearly been demonstrated in the course of monoclonal B cell dyscrasias and shown to be mostly specific for idiotypic determinants of the monoclonal immunoglobulin (Ig). These responses are specifically efficient against lymphoma cells expressing a membrane form of the monoclonal Ig. In myeloma, such immune responses are often weak and a number of strategies are currently assayed in order to boost the cell-mediated responses against the secreted monoclonal Ig. The use of cytokines promoting Th1 responses could be helpful for the induction of anti-tumour immunity and the control of residual disease in patients treated with myeloablative therapy, and such strategies need to be evaluated. In a light chain myeloma model where the monoclonal Ig can only be secreted, we tried to induce protective immune responses through immunization of animals with transfected malignant plasma cells. An expression plasmid encoding GM-CSF and IL-12 proved to be highly efficient for the induction of both cytotoxic and proliferative responses after immunization of animals with transfected and irradiated tumour cells. Anti-tumour immunization according to this protocol was successful in protecting 93.4% of the animals against a subsequent tumour challenge.

Tumor lysate-specific cytotoxic T lymphocytes in multiple myeloma: promising effector cells for immunotherapy

The idiotype protein, secreted by myeloma plasma cells, is a tumor-specific but weak antigen. Idiotype-based immunotherapy has been explored in myeloma patients with disappointing results. It is conceivable that myeloma cells contain a multitude of tumor antigens that can more effectively stimulate antitumor T cells. To explore the possibility of using whole myeloma cells as a source of tumor antigens for immunotherapy, the current study was undertaken to generate and examine the function of myeloma-specific cytotoxic T lymphocytes (CTLs) by using dendritic cells (DCs) pulsed with myeloma cell lysates as stimulating cells. After repeated stimulation, specific CTL lines, containing CD4(+) and CD8(+) T cells, were generated from myeloma patients. Our results show that these T cells not only recognized and lysed autologous myeloma protein-pulsed DCs, they also killed autologous primary myeloma cells. Occasionally, CTLs responded to autologous idiotype-pulsed DCs and to allogeneic primary myeloma cells. No cytolytic activity, however, was detected against autologous lymphocytes including B cells, suggesting that the T cells acted specifically against myeloma cells. Cytotoxicity against target cells was major histocompatibility complex class 1 and, to a lesser extent, class 2 restricted and was dependent mainly on the perforin-mediated pathway. CTLs secreted predominantly interferon-gamma and tumor necrosis factor-alpha on antigenic stimulation, indicating a type 1 T-cell subset. These findings represent the first demonstration that tumor cell lysate-primed CTLs kill only myeloma cells, not autologous lymphocytes. This provides a rationale for myeloma cell-based immunotherapy in multiple myeloma.

Improved outcome of allogeneic transplantation in high-risk multiple myeloma patients after nonmyeloablative conditioning

PURPOSE

We present our experience with relapsed and recently diagnosed patients with high-risk multiple myeloma (MM) receiving immunosuppressive, nonmyeloablative melphalan (MEL)-based conditioning regimens (mini-allograft).

PATIENTS AND METHODS

Thirty-one MM patients received allografts from HLA-matched siblings (n = 25) or unrelated donors (n = 6) using a mini-allograft. Seventeen had progressive disease (PD) and 14 had responsive disease (RD) (six with primary RD and eight with responsive relapse). Thirty patients had received one (n = 13) or two or more (n = 17) prior autologous transplantations (ATs). Median age was 56 years (range, 38 to 69 years). Twenty-one patients had chromosome 13 abnormality. Two patients were hemodialysis dependent. Blood and bone marrow grafts were administered to 28 and three patients, respectively. Donor lymphocyte infusions were given to 18 patients either to attain full donor chimerism (n = 6) or to eradicate residual disease (n = 12).

RESULTS

By day 100, 25 (89%) of 28 patients were full donor chimeras, one was a mixed chimera, and two had autologous reconstitution. Acute graft-versus-host disease (GVHD) developed in 18 patients (58%), and 10 progressed to chronic GVHD (limited in six and extensive in four). At a median follow-up of 6 months, 19 (61%) of 31 patients achieved complete/near complete remission. Twelve patients (39%) have died: three of PD, three of early treatment-related mortality (TRM) (before day 100), and six of late TRM. Median overall survival (OS) was 15 months. At 1 year, there was a significantly longer event-free survival (86% v 31%, P =.01) and OS (86% v 48%, P =.04) when a mini-allograft was performed after one versus two or more prior ATs, respectively. When compared with historical MM controls (n = 93) receiving conventional allografts, early TRM was significantly lower (10% v 29%, P =.03), and OS at 1 year was better (71% v 45%; P =.08) in the mini-allograft MM patients.

CONCLUSION

Mini-allograft induced excellent disease control in MM patients with high-risk disease, but is still associated with a significant GVHD.