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Immune Escape of Relapsed AML Cells after Allogeneic Transplantation.

ABSTRACT: BACKGROUND:As consolidation therapy for acute myeloid leukemia (AML), allogeneic hematopoietic stem-cell transplantation provides a benefit in part by means of an immune-mediated graft-versus-leukemia effect. We hypothesized that the immune-mediated selective pressure imposed by allogeneic transplantation may cause distinct patterns of tumor evolution in relapsed disease. METHODS:We performed enhanced exome sequencing on paired samples obtained at initial presentation with AML and at relapse from 15 patients who had a relapse after hematopoietic stem-cell transplantation (with transplants from an HLA-matched sibling, HLA-matched unrelated donor, or HLA-mismatched unrelated donor) and from 20 patients who had a relapse after chemotherapy. We performed RNA sequencing and flow cytometry on a subgroup of these samples and on additional samples for validation. RESULTS:On exome sequencing, the spectrum of gained and lost mutations observed with relapse after transplantation was similar to the spectrum observed with relapse after chemotherapy. Specifically, relapse after transplantation was not associated with the acquisition of previously unknown AML-specific mutations or structural variations in immune-related genes. In contrast, RNA sequencing of samples obtained at relapse after transplantation revealed dysregulation of pathways involved in adaptive and innate immunity, including down-regulation of major histocompatibility complex (MHC) class II genes ( HLA-DPA1, HLA-DPB1, HLA-DQB1, and HLA-DRB1) to levels that were 3 to 12 times lower than the levels seen in paired samples obtained at presentation. Flow cytometry and immunohistochemical analysis confirmed decreased expression of MHC class II at relapse in 17 of 34 patients who had a relapse after transplantation. Evidence suggested that interferon-? treatment could rapidly reverse this phenotype in AML blasts in vitro. CONCLUSIONS:AML relapse after transplantation was not associated with the acquisition of relapse-specific mutations in immune-related genes. However, it was associated with dysregulation of pathways that may influence immune function, including down-regulation of MHC class II genes, which are involved in antigen presentation. These epigenetic changes may be reversible with appropriate therapy. (Funded by the National Cancer Institute and others.).

SUBMITTER: Christopher MJ

PROVIDER: S-EPMC6322675 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Immune Escape of Relapsed AML Cells after Allogeneic Transplantation.

Christopher Matthew J MJ Petti Allegra A AA Rettig Michael P MP Miller Christopher A CA Chendamarai Ezhilarasi E Duncavage Eric J EJ Klco Jeffery M JM Helton Nicole M NM O'Laughlin Michelle M Fronick Catrina C CC Fulton Robert S RS Wilson Richard K RK Wartman Lukas D LD Welch John S JS Heath Sharon E SE Baty Jack D JD Payton Jacqueline E JE Graubert Timothy A TA Link Daniel C DC Walter Matthew J MJ Westervelt Peter P Ley Timothy J TJ DiPersio John F JF

The New England journal of medicine 20181031 24

<h4>Background</h4>As consolidation therapy for acute myeloid leukemia (AML), allogeneic hematopoietic stem-cell transplantation provides a benefit in part by means of an immune-mediated graft-versus-leukemia effect. We hypothesized that the immune-mediated selective pressure imposed by allogeneic transplantation may cause distinct patterns of tumor evolution in relapsed disease.<h4>Methods</h4>We performed enhanced exome sequencing on paired samples obtained at initial presentation with AML and ...[more]

PMID: 30380364

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Project description:Identifying the targets of immune response after allogeneic hematopoietic cell transplantation (HCT) promises to provide relevant immune therapy candidate proteins. We used protein microarrays to serologically identify Nucleolar and Spindle Associated Protein 1 (NuSAP1) and Chromatin Assembly Factor 1, subunit B (p60) [CHAF1b] as targets of new antibody responses that developed after allogeneic HCT. Western blots and ELISA validated their post-HCT recognition and enabled ELISA testing of 120 other allo-HCT patients. CHAF1b specific antibodies were predominantly detected in AML patients whereas NuSAP1 specific antibodies were exclusively detected in AML patients one year post-transplant (p<0.0001). Complete genomic exon sequencing failed to identify a nonsynonymous SNP for NuSAP1 and CHAF1b between the donor and recipient cells. Expression profiles and RT-PCR showed NuSAP1 was predominately expressed in the bone marrow CD34+CD90+ hematopoietic stem cells (HSC), leukemic cell lines and B lymphoblasts as compared to other tissues or cells. Thus, NuSAP1 is recognized as an immunogenic antigen in 65% AML patients and suggests a tumor antigen role. In conclusion, clinically important tumor antigens can be identified as new antibody targets after allogeneic HCT using high density protein microarrays Plasma Profiling using ProtoArrays: Protein microarrays were obtained (ProtoArraysâ¢ V3, Invitrogen Corporation, Carlsbad, CA) displaying 5,056 full-length human proteins, derived from the Ultimate ORF collection (Invitrogen Corp., Carlsbad, CA) printed in duplicate with N-terminal GST epitopes expressed in Baculovirus and affinity purified under native conditions maintaining their cellular enzymatic activities/native conformations. The arrays also contained control spots consisting of buffer, empty spots, and human IgG printed in four different concentrations (IgG[1] to IgG[4]). The arrays were incubated with blocking buffer for one hr followed by application of the plasma sample diluted 1:150 for 90 min. After washing the array four times for 10 min each with PBST buffer, secondary antibody was added (goat anti-human Alexa 647, Molecular Probes, Eugene, OR) for 90 min. After washing the slides with PBST buffer, the arrays were dried and fluorescent intensity was detected using a microarray scanner (GenePix 4000B, Molecular Devices, CA). All incubations were carried out on a rotating platform at 4 ÂºC. ProtoArray data acquisition and measurement: The slides were scanned at a PMT gain of 60% with a laser power of 90% and a focus point of 0 Î¼m. Fluorescence intensity data were acquired using GenePix Pro 6.0 software (Molecular devices, Sunnyvale, CA) with the appropriate â.galâ file downloaded from the ProtoArray central portal on the Invitrogen website (http://www.invitrogen.com/protoarray) by submitting the barcode of each ProtoArray slide

Dataset Information

Immune Escape of Relapsed AML Cells after Allogeneic Transplantation.

Publications

Immune Escape of Relapsed AML Cells after Allogeneic Transplantation.

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