Broad Cross-Presentation of the Hematopoietically Derived PR1 Antigen on Solid Tumors Leads to Susceptibility to PR1-Targeted Immunotherapy

Abstract

PR1 is a human leukocyte antigen (HLA)-A2 restricted peptide that has been targeted successfully in myeloid leukemia with immunotherapy. PR1 is derived from the neutrophil granule proteases proteinase 3 (P3) and neutrophil elastase (NE), which are both found in the tumor microenvironment. We recently showed that P3 and NE are taken up and cross-presented by normal and leukemia-derived antigen presenting cells, and that NE is taken up by breast cancer cells. We now extend our findings to show that P3 and NE are taken up and cross-presented by human solid tumors. We further show that PR1 cross-presentation renders human breast cancer and melanoma cells susceptible to killing by PR1-specific cytotoxic T lymphocytes (PR1-CTL) and the anti-PR1/HLA-A2 antibody 8F4. We also show PR1-CTL in peripheral blood from patients with breast cancer and melanoma. Together, our data identify cross-presentation as a novel mechanism through which cells that lack endogenous expression of an antigen become susceptible to therapies that target cross-presented antigens and suggest PR1 as a broadly expressed tumor antigen.

Mechanisms of leukemia resistance to antibody dependent cellular cytotoxicity

“…Several TCRm antibodies have been developed to various leukemia antigens and are in preclinical development. [13][14][15] WT1 encodes for a zinc finger transcription factor found in the embryonic development of multiple organ systems. [16][17][18] Importantly, multiple cancers have been identified with significantly increased expression of the WT1 product, including nearly all high-risk MDS, 19 CML, acute leukemias (AML, ALL) and their CD34…”

Neutrophil elastase enhances antigen presentation by upregulating human leukocyte antigen class I expression on tumor cells

“…Cell lines were validated in the institution’s sequencing and microarray facility using short tandem repeat DNA fingerprinting. The HLA-A2+ SKBR3 cell line (SKBR3-A2) was generated using lentiviral transduction, as previously described [8, 13]. Cell lines were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) with 10% fetal bovine serum (FBS), 100U/mL penicillin, and 100µg/mg streptomycin.…”

“…These dichotomous results have been attributed to a number of components of the tumor microenvironment, including tumor-associated neutrophils (TANs) and tumor-associated macrophages (TAMs) that have both pro- and anti-tumor effects on the tumor depending in part on other inflammatory mediators within the tumor milieu. TANs and TAMs within the tumor microenvironment produce azurophil granule serine proteases, including neutrophil elastase (NE), that have been implicated in modulating tumor behavior both favorably and unfavorably [5–8]. The exact mechanisms have not been elucidated.…”

“…Within the tumor microenvironment, NE is released from storage granules within TANs in response to interleukin 8 and tumor necrosis factor (TNF) alpha, which are increased at sites of inflammation [9, 10]. Although NE has been detected in tumor tissues, including breast cancer, where it was demonstrated to be a poor prognostic factor [6, 11], a number of more recent studies, including our own, have shown that TAN and soluble innate immune mediators derived from TAN, including NE, have beneficial anti-tumor immune effects [2, 7, 8]. We therefore sought to further study the mechanisms by which NE could contribute to favorable anti-tumor immunity.…”

“…In addition to endogenous expression by leukemia, our group has shown that non-hematopoietic cells can take up NE from the microenvironment and become susceptible to adaptive anti-tumor immune responses. Specifically, we showed that NE was cross-presented by breast cancer and melanoma cells and resulted in PR1 expression on the tumor cell surface, which enhanced the susceptibility of breast cancer and melanoma cells to lysis by PR1-targeting immunotherapies [8, 13]. We also demonstrated that NE uptake enhanced the CTL response targeting the peptide CCNE 144–152 , which is derived from the tumor antigen cyclin E (CCNE), a cell-cycle regulator with known prognostic value in breast cancer [7, 14, 15].…”