Publication Date:
2015-12-03
Description:
BACKGROUND: Immune checkpoint blockadewith anti-PD-1/PD-L1 therapyhas demonstrated remarkable efficacy in multiple tumor types. Biomarker candidates for predicting likelihood of response to targeted immunotherapy are being actively investigated including inhibitory or activating receptors on CD8+ lymphocytes, corresponding ligands on tumor or antigen-presenting cells (APCs), T-cell functionality, and the T-cell receptor (TCR) repertoire found within a tumor microenvironment. Myelofibrosis (MF) and Chronic Myeloid Leukemia (CML) are tumors responsive to immunotherapy, most notably allogeneic transplantation (alloSCT), and donor lymphocyte infusion. Although tyrosine kinase inhibitors can improve patient outcomes, a potentially curative therapeutic option other than alloSCT is needed. PURPOSE: To determine the immune profile of the bone marrow tumor microenvironment in patients with CML and MF compared to healthy donors in order to assess the rationale and potential efficacy of novel immune checkpoint therapies. METHODS: Cryopreserved bone marrow aspirate mononuclear cells (MNCs) from healthy donors (HDs) (n=11), untreated CML (n=9) or MF (n= 12) were analyzed by flow cytometry. CD3+ CD8+ lymphocytes were divided into naïve, central memory (CM), effector memory (EM), and terminal effector (TEMRA) subsets for analysis. Expression of immune checkpoint receptors including PD-1, 4-1BB, TIM3, LAG3, and TIGIT were evaluated on each population. Known corresponding ligands including PD-L1 and PD-L2 were assessed in CML samples on blasts, plasmacytoid dendritic cells (pDCs), myeloid dendritic cells (mDCs), and monocytes. T-cell function was evaluated by cytokine production, cytotoxicity, and proliferation in CD3+ CD8+ PD1+ or PD1- populations. To assess the TCR repertoire found within the tumor microenvironment, non-naive CD8+ T-cells were sorted into PD-1+ and PD-1- populations, and then CDR3 region of the TCRB gene, together with sufficient flanking sequence to identify most V, D, and J genes was sequenced using the immunoSEQ platform from Adaptive Biotechnologies. RESULTS: There was a significant difference in the CML CD3+ CD8+ subset distribution compared to HDs with EM% increased at 60.01% vs. 41.25% (p =0.0137), and TEMRA 44.51% vs. 20.64% (p=0.0004). CM% trended downwards (32.15% to 21.58%, p=0.118) while naïve% was equivalent in CML and HDs (22.13% vs. 20.87%). The percentage of PD-1+ non-naïve CD8+ T-cells (EM, TEMRA, CM combined) was significantly increased in CML samples at 55.14% (range 31-69%) compared to HDs at 38.98% (range 34.8% to 55.5%; p=0.0050). PD-1 expression was consistently increased across all subgroups in CML (CM: 67.06% vs 53.22%, EM: 60.01% vs. 41.25%, TEMRA: 44.51% vs 20.64% p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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