ABSTRACT
Purpose: PR1 is a human leukocyte antigen (HLA)-A2 nonameric peptide derived from neutrophil elastase (NE) and proteinase 3 (P3). We have previously shown that PR1 is cross-presented by solid tumors, leukemia, and antigen-presenting cells, including B cells. We have also shown that cross-presentation of PR1 by solid tumors renders them susceptible to killing by PR1-targeting immunotherapies. As multiple myeloma is derived from B cells, we investigated whether multiple myeloma is also capable of PR1 cross-presentation and subsequently capable of being targeted by using PR1 immunotherapies.Experimental Design: We tested whether multiple myeloma is capable of cross-presenting PR1 and subsequently becomes susceptible to PR1-targeting immunotherapies, using multiple myeloma cell lines, a xenograft mouse model, and primary multiple myeloma patient samples.Results: Here we show that multiple myeloma cells lack endogenous NE and P3, are able to take up exogenous NE and P3, and cross-present PR1 on HLA-A2. Cross-presentation by multiple myeloma utilizes the conventional antigen processing machinery, including the proteasome and Golgi, and is not affected by immunomodulating drugs (IMiD). Following PR1 cross-presentation, we are able to target multiple myeloma with PR1-CTL and anti-PR1/HLA-A2 antibody both in vitro and in vivoConclusions: Collectively, our data demonstrate that PR1 is a novel tumor-associated antigen target in multiple myeloma and that multiple myeloma is susceptible to immunotherapies that target cross-presented antigens. Clin Cancer Res; 24(14); 3386-96. ©2018 AACR.
Subject(s)
Antineoplastic Agents, Immunological/pharmacology , HLA-A2 Antigen/immunology , Multiple Myeloma/immunology , Peptide Fragments/antagonists & inhibitors , Peptide Fragments/immunology , Animals , Antigen Presentation/drug effects , Antigen Presentation/immunology , Antigen-Presenting Cells/immunology , Biological Transport , Cell Line, Tumor , Complement Activation , Cross-Priming/drug effects , Cross-Priming/immunology , Cytotoxicity, Immunologic , Disease Models, Animal , HLA-A2 Antigen/chemistry , HLA-A2 Antigen/metabolism , Humans , Immunologic Factors/pharmacology , Immunomodulation/drug effects , Mice , Multiple Myeloma/drug therapy , Multiple Myeloma/metabolism , Multiple Myeloma/pathology , Proteasome Endopeptidase Complex/metabolism , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Complete remission (CR) is the gold standard for assessing outcomes following chemotherapy for acute myelogenous leukemia (AML). "CRp," a response criterion defined as fulfillment of all criteria for CR except platelet count recovery to ≥100 × 10(9)/L, is associated with inferior outcomes following chemotherapy. The prognostic importance of CRp before allogeneic stem cell transplantation (allo-SCT) remains unknown. We analyzed a cohort of AML (n = 334) and myelodysplastic syndrome (MDS; n = 10) patients to determine the prognostic significance of achieving CR versus CRp before allo-SCT. At time of transplantation, 266 patients were in CR (CR1 and ≥CR2) and 78 in CRp (CR1p and ≥CR2p). Median follow-up was 38 months (3-131 months). Overall survival, progression-free survival, and nonrelapse mortality (NRM) were most favorable in patients transplanted in CR (CR1 or ≥CR2) compared with CRp (CR1p or ≥CR2p). Achieving CR is therefore associated with improved posttransplantation outcomes compared with achieving CRp and is a significant prognostic factor that needs to be considered when evaluating AML/MDS patients for clinical trials and allo-SCT.
