Transfer of idiotypic protein primed allogeneic marrow grafts elicits potent graft-versus-myeloma effects in mice

Establishment of a murine graft-versus-myeloma model using allogeneic stem cell transplantation

Background

Multiple myeloma (MM) is a malignant plasma cell disorder with poor long-term survival and high recurrence rates. Despite evidence of graft-versus-myeloma (GvM) effects, the use of allogeneic hematopoietic stem cell transplantation (allo-SCT) remains controversial in MM. In the current study, we investigated the anti-myeloma effects of allo-SCT from B10.D2 mice into MHC-matched myeloma-bearing Balb/cJ mice, with concomitant development of chronic graft-versus-host disease (GvHD).

Methods and results

Balb/cJ mice were injected intravenously with luciferase-transfected MOPC315.BM cells, and received an allogeneic (B10.D2 donor) or autologous (Balb/cJ donor) transplant 30 days later. We observed a GvM effect in 94% of the allogeneic transplanted mice, as the luciferase signal completely disappeared after transplantation, whereas all the autologous transplanted mice showed myeloma progression. Lower serum paraprotein levels and lower myeloma infiltration in bone marrow and spleen in the allogeneic setting confirmed the observed GvM effect. In addition, the treated mice also displayed chronic GvHD symptoms. In vivo and in vitro data suggested the involvement of effector memory CD4 and CD8 T cells associated with the GvM response. The essential role of CD8 T cells was demonstrated in vivo where CD8 T-cell depletion of the graft resulted in reduced GvM effects. Finally, TCR Vβ spectratyping analysis identified Vβ families within CD4 and CD8 T cells, which were associated with both GvM effects and GvHD, whereas other Vβ families within CD4 T cells were associated exclusively with either GvM or GvHD responses.

Conclusions

We successfully established an immunocompetent murine model of graft-versus-myeloma. This is the first murine GvM model using immunocompetent mice that develop MM which closely resembles human MM disease and that are treated after disease establishment with an allo-SCT. Importantly, using TCR Vβ spectratyping, we also demonstrated the presence of GvM unique responses potentially associated with the curative capacity of this immunotherapeutic approach.

Cellular immunotherapy in multiple myeloma: lessons from preclinical models

The majority of multiple myeloma patients relapse with the current treatment strategies, raising the need for alternative therapeutic approaches. Cellular immunotherapy is a rapidly evolving field and currently being translated into clinical trials with encouraging results in several cancer types, including multiple myeloma. Murine multiple myeloma models are of critical importance for the development and refinement of cellular immunotherapy. In this review, we summarize the immune cell changes that occur in multiple myeloma patients and we discuss the cell-based immunotherapies that have been tested in multiple myeloma, with a focus on murine models.

Donor immunization with WT1 peptide augments antileukemic activity after MHC-matched bone marrow transplantation

The curative potential of MHC-matched allogeneic bone marrow transplantation (BMT) is in part because of immunologic graft-versus-tumor (GvT) reactions mediated by donor T cells that recognize host minor histocompatibility antigens. Immunization with leukemia-associated antigens, such as Wilms Tumor 1 (WT1) peptides, induces a T-cell population that is tumor antigen specific. We determined whether allogeneic BMT combined with immunotherapy using WT1 peptide vaccination of donors induced more potent antitumor activity than either therapy alone. WT1 peptide vaccinations of healthy donor mice induced CD8(+) T cells that were specifically reactive to WT1-expressing FBL3 leukemia cells. We found that peptide immunization was effective as a prophylactic vaccination before tumor challenge, yet was ineffective as a therapeutic vaccination in tumor-bearing mice. BMT from vaccinated healthy MHC-matched donors, but not syngeneic donors, into recipient tumor-bearing mice was effective as a therapeutic maneuver and resulted in eradication of FBL3 leukemia. The transfer of total CD8(+) T cells from immunized donors was more effective than the transfer of WT1-tetramer(+)CD8(+) T cells and both required CD4(+) T-cell help for maximal antitumor activity. These findings show that WT1 peptide vaccination of donor mice can dramatically enhance GvT activity after MHC-matched allogeneic BMT.

Augmentation of antitumor immune responses after adoptive transfer of bone marrow derived from donors immunized with tumor lysate-pulsed dendritic cells

We demonstrated previously that tumor lysate-pulsed dendritic cells (TP-DC) could mediate a specific and long-lasting antitumor immune response against a weakly immunogenic breast tumor during early lymphoid reconstitution. The purpose of this study was to examine the potential therapeutic efficacy of bone marrow transplants from TP-DC-vaccinated donors. In 2 aggressive metastatic models, bone marrow transplantation with donor bone marrow cells from TP-DC-immunized mice mediated a tumor-specific immune response in the recipient, and this caused regressions of preexisting tumor metastases. After vaccination with TP-DC, donors harbored increased numbers of both activated CD4+ and CD8+ T-cell populations in the bone marrow. Adoptive transfer of T cells purified from the bone marrow of TP-DC-vaccinated mice led to a reduction in preestablished lung metastases, whereas depletion of T cells from bone marrow abolished this effect. By using T cells derived from the bone marrow of TP-DC-vaccinated major histocompatibility complex class I and class II knockout mice, the effector cells required for the observed antitumor effect were determined to be major histocompatibility complex class I-restricted CD8+ T cells. Additionally, the tumor burden in TP-DC-immunized transplant recipients could be reduced further by repetitive TP-DC immunizations after bone marrow transplantation. Collectively, these results demonstrate an important therapeutic role of bone marrow from TP-DC-immunized donors and raise the potential for this approach in patients with advanced cancer.

Graft-versus-lymphoma effects: clinical review, policy proposals, and immunobiology

The indubitable existence of a graft-versus-lymphoma (GVL) effect is difficult to prove directly. This article reviews the difficulties in interpreting the current literature in this field and, with a number of caveats, argues for the existence of a clinically meaningful GVL effect in follicular, mantle cell, small lymphocytic, and Hodgkin lymphomas. The evidence, however, for a potent GVL effect in diffuse large-cell lymphoma and Burkitt lymphoma is not convincing. Policies for allografting in lymphoma are proposed on the basis of this evidence. The immunobiology of GVL effects is discussed--in particular, the expression of HLA class I and II and co-stimulatory molecules on lymphomas that influence the generation of alloreactive T cells--together with future directions in immunotherapy that may help to eradicate chemoresistant disease.

Therapeutic effects of idiotype vaccination can be enhanced by the combination of granulocyte-macrophage colony-stimulating factor and interleukin 2 in a myeloma model

Idiotype (Id) vaccination provides an interesting immunotherapeutic strategy against B-cell lymphomas. In multiple myeloma (MM), however, the therapeutic efficacy of Id vaccination has been disappointing. In an attempt to improve the antitumoral potential, we added granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin 2 (IL-2) to the protocol. Balb/c mice were inoculated i.p. (d 2) with different doses (1-5 x 10(5)) of HOPC myeloma cells secreting the Ig(HOPC) Id protein. Two days later, animals were injected with 10,000 U GM-CSF i.p. for 6 d consecutively (d 0-5). On d 5 and 11, myeloma-specific immunoglobulin (Ig(HOPC)) was administered i.p. together with incomplete Freund adjuvans followed by IL-2 (2 x 10,000 U/d; i.p) for 10 d (d 5-14). In animals inoculated with 10(5) myeloma cells, treatment with IL-2 given as a single agent prolonged the median survival time (MST, 67 d) when compared with the tumour control group (MST 48 d), whereas GM-CSF did not elicit any survival benefit (MST 49 d). Complete tumour rejection could be achieved in 27% (4/15) by the combination of Id vaccination and GM-CSF. Additional treatment with IL-2 further increased antimyeloma activity. In this case, 59% of the animals showed no signs of tumour recurrence. In mice with high tumour burden (5 x 10(5)), no treatment modality achieved long-term survivors. Both natural killer (NK) cells and CD8+ T cells may be involved in the anti-tumoural immune response. These data provide evidence for the combined use of GM-CSF and IL-2 to enhance the therapeutic effectiveness of clinical cancer vaccination protocols.

Enhanced antitumoral effectiveness of idiotype vaccination induced by the administration of Flt3 ligand combined with interleukin 2 against a murine myeloma

Idiotype (Id) vaccination provides an innovative treatment modality against B-cell malignancies. In multiple myeloma patients, however, the antitumoral potential of this immunotherapeutic concept is limited. In an attempt to improve the therapeutic effectiveness of Id vaccination, we added Flt3 ligand (Flt3-L) and interleukin 2 (IL-2) to the protocol. Balb/c mice were inoculated i.p. (d -2) with different doses (1-5 x 10(5)) of HOPC myeloma cells, secreting the IgHOPC Id-protein. Two days later, animals were treated with Flt3-L (10 microg per mouse/d, given i.p) for 10 consecutive days (d 0-9). On d 5 and d 11, myeloma-specific immunoglobulin (Ig(HOPC)) was administered s.c., together with incomplete Freund adjuvans (IFA) followed by the administration of IL-2 (2 x 10.000/d given i.p) for 10 d (d 5-14). Whereas Ig(HOPC), Flt3-L or IL-2, given alone, did not elicit long-term survival, the combination of IL-2 or Flt3-L with Id vaccination achieved a complete tumour rejection in 27% and 41% of mice respectively. However, the most powerful antimyeloma effects were induced by Flt3-L + Id vaccination + IL-2: 81% of the treated animals experienced long-term survival (> 180 d). Both natural killer (NK) cells and CD8+ T cells may be involved in the antitumoral immune response. These data suggest that the combination of Flt3-L and IL-2 can be used to enhance the therapeutic effectiveness of clinical cancer vaccination protocols.

Idiotype protein-pulsed dendritic cells produce strong anti-myeloma effects after syngeneic stem cell transplantation in mice

Dendritic cell (DC) vaccination represents an interesting immunotherapeutic option in the treatment of several malignancies. In multiple myeloma (MM) patients, vaccination with autologous idiotype (Id) protein-pulsed DC is feasible, but their antitumoral effectiveness was rather limited. To improve the therapeutic potential of DC therapy, we studied the immunological effects of syngeneic peripheral blood stem cell transplantation (PBSCT) given in conjunction with Id-loaded DC. Balb/c mice were inoculated i.p. with 5 x 10(5) of HOPC myeloma cells (Balb/c origin). Animals were immunized with three injections of 5 x 10(5) DC pulsed with the IgG2a(HOPC) or with a control immunoglobulin (Ig(control)). Some experimental groups of myeloma-bearing animals received total body irradiation (7.5 Gy) and a subsequent transplant of 2 x 10(7)syngeneic peripheral blood progenitor cells (PBPC) followed by DC therapy beginning at day 10 post transplant. Animals receiving DC therapy or syngeneic PBPCT alone neither induce long-term survival nor tumor-specific CTL reactivity in vitro. In marked contrast, combination of syngeneic PBPC transplantation and subsequent DC therapy resulted in 78% survival after a follow-up of 180 days. In addition, this treatment modality conferred a generation of Id peptide-specific CD8-mediated T cell reactivity. These data provide a rationale for DC-based vaccination in multiple myeloma patients administered post syngeneic transplantation.