Christine Canning

Immunologic and clinical effects of antibody blockade of cytotoxic T lymphocyte-associated antigen 4 in previously vaccinated cancer patients

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) functions as a negative regulator of endogenous and vaccine-induced antitumor immunity. The administration of fully human anti-CTLA-4 blocking monoclonal antibodies to advanced-cancer patients increases immune-mediated tumor destruction in some subjects. Nonetheless, patients that respond also frequently manifest serious inflammatory pathologies, raising the possibility that the therapeutic and toxic effects of CTLA-4 blockade might be linked. Here we show that periodic infusions of anti-CTLA-4 antibodies after vaccination with irradiated, autologous tumor cells engineered to secrete GM-CSF (GVAX) generate clinically meaningful antitumor immunity without grade 3 or 4 toxicity in a majority of metastatic melanoma patients. The application of this sequential immunotherapy to advanced ovarian carcinoma patients also revealed that tumor destruction and severe inflammatory pathology could be dissociated, although further refinements are required to increase clinical responses and to minimize toxicity in this population. The extent of therapy-induced tumor necrosis was linearly related to the natural logarithm of the ratio of intratumoral CD8+ effector T cells to FoxP3+ regulatory T cells (Tregs) in posttreatment biopsies. Together, these findings help clarify the immunologic and clinical effects of CTLA-4 antibody blockade in previously vaccinated patients and raise the possibility that selective targeting of antitumor Tregs may constitute a complementary strategy for combination therapy.

Detection of a potent humoral response associated with immune-induced remission of chronic myelogenous leukemia

The effectiveness of donor-lymphocyte infusion (DLI) for treatment of relapsed chronic myelogenous leukemia (CML) after allogeneic bone marrow transplantation is a clear demonstration of the graft-versus-leukemia (GVL) effect. T cells are critical mediators of GVL, but the antigenic targets of this response are unknown. To determine whether patients who respond to DLI also develop B-cell immunity to CML-associated antigens, we analyzed sera from three patients with relapsed CML who achieved a complete molecular remission after infusion of donor T cells. Sera from these individuals recognized 13 distinct gene products represented in a CML-derived cDNA library. Two proteins, Jkappa-recombination signal-binding protein (RBP-Jkappa) and related adhesion focal tyrosine kinase (RAFTK), were recognized by sera from three of 19 DLI responders. None of these antigens were recognized by sera from healthy donors or patients with chronic graft-versus-host disease. Four gene products were recognized by sera from CML patients treated with hydroxyurea and nine were detected by sera from CML patients who responded to IFN-alpha. Antibody titers specific for RAFTK, but not for RBP-Jkappa, were found to be temporally associated with the response to DLI. These results demonstrate that patients who respond to DLI generate potent antibody responses to CML-associated antigens, suggesting the development of coordinated T- and B-cell immunity. The characterization of B cell-defined antigens may help identify clinically relevant targets of the GVL response in vivo.

Comparative Outcomes of T-Cell–Depleted and Non–T-Cell–Depleted Allogeneic Bone Marrow Transplantation for Chronic Myelogenous Leukemia: Impact of Donor Lymphocyte Infusion

PURPOSE Donor lymphocyte infusion (DLI) can restore complete remission in patients with chronic myelogenous leukemia (CML) who have relapsed after T-cell-depleted (TCD) allogeneic bone marrow transplantation (BMT). The existence of salvage treatment for patients with DLI after TCD allogeneic BMT prompted an evaluation of overall outcome after CD6+ -TCD allogeneic BMT for patients treated during the time when DLI has been available. PATIENTS AND METHODS We performed a retrospective analysis of outcomes of 46 patients who underwent TCD allogeneic BMT for stable-phase CML and compared these outcomes with those of 40 patients who underwent non-TCD allogeneic BMT. All subjects were patients at one of two neighboring institutions during a period when DLI was available. All patients received marrow from HLA-identical sibling donors, underwent similar myeloablative regimens, and had similar pretreatment characteristics. RESULTS After BMT, the TCD group had a lower incidence of grade 2 to 4 acute (15% v 37%, P = .026) and chronic graft-versus-host disease (GVHD) (18% v 42%, P = .024) than did the non-TCD group. The 1-year treatment-related mortality rates for the TCD group and the non-TCD group were 13% and 29%, respectively (P = .07). The estimated 3-year probability of relapse (cytogenetic or hematologic) was higher for patients in the TCD group than for patients in the non-TCD group (62% v 24%, P = .0003). Twenty-three patients (20 in the TCD group and three in the non-TCD group) received and were assessable for response to DLI. After DLI, 17 of 20 patients in the TCD group and two of three patients in the non-TCD group achieved complete remission. Donor lymphocyte infusion induced GVHD in nine of 23 patients. Thirty (65%) of 46 patients in the TCD group and 27 (69%) of 39 assessable patients in the non-TCD group remained alive without evidence of disease. The estimated 3-year overall survival rates were similar for the TCD group and the non-TCD group (72% v 68%, respectively; P = .38). At last follow-up, there was no difference in the overall prevalence of GVHD or the proportion of patients requiring immunosuppressive agents between groups. CONCLUSION These results suggest that the combination of T-cell depletion and post-BMT DLI is a viable treatment option for patients undergoing allogeneic BMT for CML and should be prospectively compared with traditional forms of GVHD prophylaxis.

CML66, a broadly immunogenic tumor antigen, elicits a humoral immune response associated with remission of chronic myelogenous leukemia

This report describes a tumor-associated antigen, termed CML66, initially cloned from a chronic myelogenous leukemia (CML) cDNA expression library. CML66 encodes a 583-aa protein with a molecular mass of 66 kDa and no significant homology to other known genes. CML66 gene is localized to human chromosome 8q23, but the function of this gene is unknown. CML66 is expressed in leukemias and a variety of solid tumor cell lines. When examined by Northern blot, expression in normal tissues was restricted to testis and heart, and no expression was found in hematopoietic tissues. When examined by quantitative reverse transcription–PCR, expression in CML cells was 1.5-fold higher than in normal peripheral blood mononuclear cells. The presence of CML66-specific antibody in patient serum was confirmed by Western blot and the development of high titer IgG antibody specific for CML66 correlated with immune induced remission of CML in a patient who received infusion of normal donor lymphocytes for treatment of relapse. CML66 antibody also was found in sera from 18–38% of patients with lung cancer, melanoma, and prostate cancer. These findings suggest that CML66 may be immunogenic in a wide variety of malignancies and may be a target for antigen-specific immunotherapy.

Biologic activity of irradiated, autologous, GM-CSF-secreting leukemia cell vaccines early after allogeneic stem cell transplantation

Through an immune-mediated graft-versus-leukemia effect, allogeneic hematopoietic stem cell transplantation (HSCT) affords durable clinical benefits for many patients with hematologic malignancies. Nonetheless, subjects with high-risk acute myeloid leukemia or advanced myelodysplasia often relapse, underscoring the need to intensify tumor immunity within this cohort. In preclinical models, allogeneic HSCT followed by vaccination with irradiated tumor cells engineered to secrete GM-CSF generates a potent antitumor effect without exacerbating the toxicities of graft-versus-host disease (GVHD). To test whether this strategy might be similarly active in humans, we conducted a Phase I clinical trial in which high-risk acute myeloid leukemia or myelodysplasia patients were immunized with irradiated, autologous, GM-CSF-secreting tumor cells early after allogeneic, nonmyeloablative HSCT. Despite the administration of a calcineurin inhibitor as prophylaxis against GVHD, vaccination elicited local and systemic reactions that were qualitatively similar to those previously observed in nontransplanted, immunized solid-tumor patients. While the frequencies of acute and chronic GVHD were not increased, 9 of 10 subjects who completed vaccination achieved durable complete remissions, with a median follow-up of 26 months (range 12–43 months). Six long-term responders showed marked decreases in the levels of soluble NKG2D ligands, and 3 demonstrated normalization of cytotoxic lymphocyte NKG2D expression as a function of treatment. Together, these results establish the safety and immunogenicity of irradiated, autologous, GM-CSF-secreting leukemia cell vaccines early after allogeneic HSCT, and raise the possibility that this combinatorial immunotherapy might potentiate graft-versus-leukemia in patients.

Outcome after autologous and allogeneic stem cell transplantation for patients with multiple myeloma: impact of graft-versus-myeloma effect

Summary:A total of 228 patients with multiple myeloma (MM), 166 patients receiving autologous transplantation (124 PBSC and 38 BM) and 66 patients receiving T-cell-depleted allogeneic transplantation were analyzed to compare overall survival (OS), progression-free survival (PFS) and risk of relapse. Patients receiving autologous transplantation had a significantly improved OS (P=0.006) and PFS (P=0.002) at 2 years with OS and PFS for autologous transplant 74% and 48%, respectively, compared with 51% and 28% for allogeneic transplantation. By 4 years after transplantation, outcome was similar with OS and PFS for autologous transplantation 41% and 23%, respectively, compared with 39% and 18% for allogeneic transplantation. The 4-year cumulative incidence of nonrelapse mortality was significantly higher in patients receiving allogeneic transplantation (24% vs 13%) (P=0.004). Relapse was the principle cause of treatment failure for both groups; however, there was a significantly reduced risk of relapse associated with allogeneic transplantation at 4 years: 46% for allograft vs 56% for autograft (P=0.02). Despite a lower risk of relapse after allogeneic transplantation, autologous transplantation is associated with improved OS and PFS compared with allogeneic transplantation in patients with MM. Strategies focused on reducing nonrelapse mortality in allogeneic transplantation may translate into an improved outcome for patients receiving allogeneic transplantation.

Changes in T cell receptor repertoire associated with graft-versus-tumor effect and graft-versus-host disease in patients with relapsed multiple myeloma after donor lymphocyte infusion

Recent reports of clinical responses following donor lymphocyte infusions (DLI) in patients with relapsed multiple myeloma (MM) after allogeneic BMT have demonstrated the ability of allogeneic cells to mediate a graft-versus-myeloma (GVM) effect, but the mechanisms involved have not been determined. To identify changes in the T cell compartment associated with DLI, we performed a molecular analysis of the T cell receptor (TCR) repertoire in four patients with relapsed MM who received infusions of CD4+ lymphocytes from HLA-identical sibling donors. Three of the four patients demonstrated a clinical anti-myeloma response following DLI but also developed graft-versus-host disease (GVHD). The TCR repertoire was examined after PCR amplification of 24 Vβ gene subfamilies. This method determines the relative utilization of each Vβ gene subfamily and also allows the identification of clonal and oligoclonal T cell populations through analysis of CDR3 regions for each TCR Vβ gene subfamily. Serial blood samples were obtained over at least a 1 year period before and after DLI and results compared to 10 normal donors. Serial analysis of CDR3 size profiles demonstrated the appearance of clonal T cell populations after DLI in each of the three responding patients. The appearance of some clones was noted within the first 3 months after DLI and coincided with decreasing levels of monoclonal paraprotein indicating an ongoing GVM response. Other T cell clones appeared at later time points and coincided with the development of GVHD. These findings demonstrate that T cell clones with different patterns of onset can be identified in the peripheral blood of MM patients following DLI. Further functional characterization of these distinct clonal expansions will be required to determine whether these T cell clones are mediators of either anti-myeloma or anti-host activity. Bone Marrow Transplantation (2000) 25, 623–632.

Conversion to full donor chimerism following donor lymphocyte infusion is associated with disease response in patients with multiple myeloma

Donor lymphocyte infusions (DLIs) have been demonstrated to induce clinical responses in patients with relapsed multiple myeloma after allogeneic bone marrow transplantation, but the immunologic mechanisms involved have not been well characterized. In patients with chronic myelocytic leukemia (CML), remissions following DLI are invariably associated with conversion to complete donor hematopoiesis, suggesting that the target antigens of this response are expressed on both normal and CML-derived hematopoietic stem cells. In the present study, we examined hematopoietic chimerism and the complexity of the T-cell receptor (TCR) repertoire in 4 patients with relapsed multiple myeloma who received infusions of donor CD4+ lymphocytes. Three of 4 patients had a clinical response that began 1 to 2 months after DLI. All 3 responding patients developed lymphocytosis at the initiation of response that was due to a 2- to 4.5-fold increase in the number of CD3+ T cells. In 1 patient, this was due primarily to increases in CD3+ and CD8+ cells; in 2 patients, to increased numbers of CD3+ and CD8+ and CD3+ and CD4+ T cells. In all responding patients, conversion to complete donor hematopoiesis occurred in the first 2 months after DLI. The single nonresponding patient remained it 100% recipient hematopoiesis. The TCR repertoire complexity was examined by polymerase chain reaction amplification of complementary-determining region 3 (CDR3) derived from 24 Vbeta gene subfamilies. In 2 patients, the initiation of myeloma response and conversion to complete donor hematopoiesis was associated with normalization of TCR complexity. Complete donor chimerism and normal TCR complexity remained stable in all patients and did not change with subsequent relapse or development of graft-versus-host disease (GVHD). Thus, conversion to full donor chimerism was temporally associated with the antimyeloma effect of DLI but not with the development of GVHD. Nevertheless, the maintenance of stable donor hematopoiesis did not prevent disease relapse and was not associated with prolonged remission. The selective relapse of myeloma cells without concomitant return of mixed hematopoietic chimerism suggests that myeloma tumor cells in some patients develop resistance to immune destruction.

Autologous CLL cell vaccination early after transplant induces leukemia-specific T cells

BACKGROUND Patients with advanced hematologic malignancies remain at risk for relapse following reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (allo-HSCT). We conducted a prospective clinical trial to test whether vaccination with whole leukemia cells early after transplantation facilitates the expansion of leukemia-reactive T cells and thereby enhances antitumor immunity. METHODS We enrolled 22 patients with advanced chronic lymphocytic leukemia (CLL), 18 of whom received up to 6 vaccines initiated between days 30 and 45 after transplantation. Each vaccine consisted of irradiated autologous tumor cells admixed with GM-CSF-secreting bystander cells. Serial patient PBMC samples following transplantation were collected, and the impact of vaccination on T cell activity was evaluated. RESULTS At a median follow-up of 2.9 (range, 1-4) years, the estimated 2-year progression-free and overall survival rates of vaccinated subjects were 82% (95% CI, 54%-94%) and 88% (95% CI, 59%-97%), respectively. Although vaccination only had a modest impact on recovering T cell numbers, CD8+ T cells from vaccinated patients consistently reacted against autologous tumor, but not alloantigen-bearing recipient cells with increased secretion of the effector cytokine IFN-γ, unlike T cells from nonvaccinated CLL patients undergoing allo-HSCT. Further analysis confirmed that 17% (range, 13%-33%) of CD8+ T cell clones isolated from 4 vaccinated patients by limiting dilution of bulk tumor-reactive T cells solely reacted against CLL-associated antigens. CONCLUSION Our studies suggest that autologous tumor cell vaccination is an effective strategy to advance long-term leukemia control following allo-HSCT. TRIAL REGISTRATION Clinicaltrials.gov NCT00442130. FUNDING NCI (5R21CA115043-2), NHLBI (5R01HL103532-03), and Leukemia and Lymphoma Society Translational Research Program.

CD8+ cell depletion of donor lymphocyte infusions using cd8 monoclonal antibody-coated high-density microparticles (CD8-HDM) after allogeneic hematopoietic stem cell transplantation: A pilot study

Summary:A CD8 murine monoclonal antibody-coated high-density microparticle (HDM) has been developed, which allows for the rapid depletion of CD8+ T cells from apheresis products by gravity sedimentation. We conducted a study to determine the efficacy and safety of CD8 depletion of donor lymphocyte infusions (DLI) to treat relapse after stem cell transplantation using the Eligix CD8-HDM Cell Separation System. Patients were targeted to receive 3 × 107 CD4+ T cells/kg. Nine patients were enrolled, three with CML, three myeloma, two CLL, and one NHL. A median of 1 × 1010 mononuclear cells were obtained by apheresis and processed. The median depletion of CD8+ cells was 99.3% (97.8−>99.5%). CD8 depletion was highly specific, with a median recovery of CD4+ cells of 75%. A median of 2.9 × 107 CD4+ cells/kg was infused. No infusional toxicity was noted. All CML patients achieved a complete molecular remission. A CLL patient demonstrated a complete response. One patient developed GVHD (grade II acute GVHD and subsequently chronic GVHD). The CD8-HDM Cell Separation System appears to be highly selective and effective in depleting CD8+ T cells from DLI apheresis products, and CD8-depleted DLI is capable of mediating a graft-versus-leukemia effect while minimizing GVHD.