Angiogenic Cytokines Are Antibody Targets During Graft-versus-Leukemia Reactions

Abstract

Purpose The graft-versus-leukemia (GVL) reaction is an important example of immune-mediated tumor destruction. A coordinated humoral and cellular response accomplishes leukemia cell killing, but the specific targets remain largely uncharacterized. To learn more about the antigens that elicit antibodies during GVL reactions, we analyzed advanced myelodysplasia (MDS) and acute myeloid leukemia (AML) patients who received an autologous, granulocyte-macrophage colony stimulating factor (GM-CSF) secreting tumor cell vaccine early after allogeneic hematopoietic stem cell transplantation (HSCT). Experimental Design A combination of tumor-derived cDNA expression library screening, protein microarrays, and antigen-specific ELISAs were employed to characterize sera obtained longitudinally from 15 AML/MDS patients who were vaccinated early after allogeneic HSCT. Results A broad, therapy-induced antibody response was uncovered, which primarily targeted intracellular proteins that function in growth, transcription/translation, metabolism, and homeostasis. Unexpectedly, antibodies were also elicited against eight secreted angiogenic cytokines that play critical roles in leukemogenesis. Antibodies to the angiogenic cytokines were evident early after therapy, and in some patients manifested a diversification in reactivity over time. Patients that developed antibodies to multiple angiogenic cytokines showed prolonged remission and survival. Conclusions These results reveal a potent humoral response during GVL reactions induced with vaccination early after allogeneic HSCT and raise the possibility that antibodies, in conjunction with NK cells and T lymphocytes, may contribute to immune-mediated control of myeloid leukemias.

Improving immune–vascular crosstalk for cancer immunotherapy

“…Serum levels of Ang2, a vessel-destabilizing ligand of Tie2 and a critical regulator of blood vessel maturation 106 , were found to inversely correlate with both clinical response rate and survival in melanoma patients treated with the anti-CTLA4 antibody, ipilimumab 107 . Similarly, humoral responses against proangiogenic cytokines including Ang2 and VEGFA were found to predict long-term remission and survival in patients with acute myeloid leukemia that had received tumour cell vaccines after allogeneic hematopoietic stem cell transplantation, and also in patients with NSCLC treated with tumour vaccines 108,109 . Together, these findings support the interconnecting relationship between tumour vascular remodeling and the generation of antitumor immune responses, and they further highlight the potential role of using vascular-related biomarkers as a surrogate to predict clinical responses to cancer immunotherapies.…”

Vaccination with autologous myeloblasts admixed with GM-K562 cells in patients with advanced MDS or AML after allogeneic HSCT

“…Screening of postvaccination antibody responses to a panel of angiogenic cytokines (L1-CAM, DEL-1, Ang1, Ang2, HGF, PDGF, VEGF-A, and PRGN) was performed by ELISA, as previous described. 21 …”

“…21 These include L1CAM, DEL-1, angiopoietin-1, angiopoietin-2, VEGF-A, progranulin, platelet-derived growth-BB, and hepatocyte growth factor. As shown on Table 3, robust ($21) peak antibody responses against these proteins were observed.…”

“…20 In this study, 9 of 10 patients who completed vaccinations had durable complete remissions, and correlative studies demonstrated coordinated NK-, T-, and B-cell responses after vaccination, with reduction in levels of the circulating soluble NKG2D ligands MICA and MICB, and robust antibody responses against angiogenic cytokines including angiopoietin 1 and 2, which were not present in nonvaccinated patients after HSCT. 20,21 A disadvantage of this GVAX platform is that autologous leukemia cells were transduced with an adenoviral construct such that the tumor cell was the source of both antigen and GM-CSF production. This approach is hampered by the inconsistent transduction efficiency of autologous cells, resulting in highly variable production of GM-CSF from individual vaccine preparations.…”

Special Conference on Tumor Immunology and Immunotherapy: A New Chapter

“…This vasculopathy is the result of antibody responses against angiogenic proteins including VEGF and angiopoetins 1 and 2, leading to reduced macrophage infiltration. Further targeting of angiogenesis using ipilimumab and bevacizumab (anti-VEGF) led to the development of blood vessels within the tumor that resemble high endothelial venules (HEV) and increased T-cell infiltration (16, 17). Monoclonal antibodies developed from the sera of long-term survivors are now being produced for clinical trials (18).…”