Impact of curative radiotherapy on the immune status of patients with localized prostate cancer

Combination of radiotherapy with immunotherapy has become an attractive concept for the treatment of cancer. The objective of this study was to assess the effect of curative, normofractionated radiotherapy on peripheral immune lymphocytes in prostate cancer patients, in order to propose a rationale for scheduling of normofractionated radiotherapy with T-cell based immunotherapy. In a prospective study (clinicaltrials.gov: NCT01376674), eighteen patients with localized prostate cancer were treated with radiotherapy with or without hormonal therapy. Irradiation volumes encompassed prostate and, in select cases, elective pelvic nodal regions. Blood samples were collected from all patients before, during, and after radiotherapy, as well as from 6 healthy individuals as control. Normofractionated radiotherapy of prostate cancer over eight weeks had a significant influence on the systemic immune status of patients compared to healthy controls. Absolute leukocyte and lymphocyte counts decreased during treatment as did peripheral blood immune subsets (T cells, CD8+ and naïve CD4+ T cells, B cells). Regulatory T cells and NK cells increased. Proliferation of all immune cells except regulatory T cells increased during RT. Most of these changes were transient. Importantly, the functionality of T lymphocytes and the frequency of antigen-specific CD8+ T cells were not affected during therapy. Our data indicate that combination of normofractionated radiotherapy with immunotherapy might be feasible for patients with prostate cancer. Conceptually, beginning with immunotherapy early during the course of radiotherapy could be beneficial, as the percentage of T cells is highest, the percentage of regulatory T cells is lowest, and as the effects of radiotherapy did not completely subside 3 months after end of radiotherapy.

Validation of Immunomonitoring Methods for Application in Clinical Studies: The HLA-Peptide Multimer Staining Assay

BACKGROUND

Validated assays are essential to generate data with defined specificity, consistency, and reliability. Although the process of validation is required for applying immunoassays in the context of clinical studies, reports on systematic validation of in vitro T cell assays are scarce so far. We recently validated our HLA-peptide multimer staining assay in a systematic manner so as to qualify the method for monitoring antigen-specific T cell responses after immunotherapy.

METHODS

Parameters of the assay, specificity, precision, linearity, sensitivity, and robustness were assessed systematically. Experiments were designed to address specifically each parameter and are detailed.

RESULTS

Nonspecific multimer staining was below the acceptance limit of 0.02% multimer(+) CD8(+) cells. The assay showed acceptable precision in all dimensions it was repeated (CV < 10%) and also demonstrated a linear detection (R2  > 0.99) of antigen specific cells.

CONCLUSIONS

We succeeded in validating the HLA-multimer staining assay in a systematic manner. Additionally, we propose a technical framework and recommendations that can be applied for validating other T cell assessment methods. © 2016 International Clinical Cytometry Society.

A Simple and Rapid Method for Quality Control of Major Histocompatibility Complex-Peptide Monomers by Flow Cytometry

Major histocompatibility complex (MHC) multimers are essential tools in T cell immunomonitoring, which are employed both in basic and clinical research, as well as for assessing clinical samples during therapy. The generation of MHC monomers loaded with synthetic peptides is an elaborate and time-consuming process. It would be beneficial to assess the quality of these monomers prior to downstream applications. In this technical note, we describe a novel flow cytometry-based, cell-free, quick, and robust assay to check the quality of MHC monomers directly after refolding or after long-term storage.

Mapping the HLA ligandome landscape of acute myeloid leukemia: a targeted approach toward peptide-based immunotherapy

Identification of physiologically relevant peptide vaccine targets calls for the direct analysis of the entirety of naturally presented human leukocyte antigen (HLA) ligands, termed the HLA ligandome. In this study, we implemented this direct approach using immunoprecipitation and mass spectrometry to define acute myeloid leukemia (AML)-associated peptide vaccine targets. Mapping the HLA class I ligandomes of 15 AML patients and 35 healthy controls, more than 25 000 different naturally presented HLA ligands were identified. Target prioritization based on AML exclusivity and high presentation frequency in the AML cohort identified a panel of 132 LiTAAs (ligandome-derived tumor-associated antigens), and 341 corresponding HLA ligands (LiTAPs (ligandome-derived tumor-associated peptides)) represented subset independently in >20% of AML patients. Functional characterization of LiTAPs by interferon-γ ELISPOT (Enzyme-Linked ImmunoSpot) and intracellular cytokine staining confirmed AML-specific CD8(+) T-cell recognition. Of note, our platform identified HLA ligands representing several established AML-associated antigens (e.g. NPM1, MAGED1, PRTN3, MPO, WT1), but found 80% of them to be also represented in healthy control samples. Mapping of HLA class II ligandomes provided additional CD4(+) T-cell epitopes and potentially synergistic embedded HLA ligands, allowing for complementation of a multipeptide vaccine for the immunotherapy of AML.

Identification of HLA ligands and T-cell epitopes for immunotherapy of lung cancer

INTRODUCTION

Lung cancer is the most common cancer worldwide. Every year, as many people die of lung cancer as of breast, colon and rectum cancers combined. Because most patients are being diagnosed in advanced, not resectable stages and therefore have a poor prognosis, there is an urgent need for alternative therapies. Since it has been demonstrated that a high number of tumor- and stromal-infiltrating cytotoxic T cells (CTLs) is associated with an increased disease-specific survival in lung cancer patients, it can be assumed that immunotherapy, e.g. peptide vaccines that are able to induce a CTL response against the tumor, might be a promising approach.

METHODS

We analyzed surgically resected lung cancer tissues with respect to HLA class I- and II-presented peptides and gene expression profiles, aiming at the identification of (novel) tumor antigens. In addition, we tested the ability of HLA ligands derived from such antigens to generate a CTL response in healthy donors.

RESULTS

Among 170 HLA ligands characterized, we were able to identify several potential targets for specific CTL recognition and to generate CD8+ T cells which were specific for peptides derived from cyclin D1 or protein-kinase, DNA-activated, catalytic polypeptide and lysed tumor cells loaded with peptide.

CONCLUSIONS

This is the first molecular analysis of HLA class I and II ligands ex vivo from human lung cancer tissues which reveals known and novel tumor antigens able to elicit a CTL response.

The recombinant bifunctional protein αCD133-GPVI promotes repair of the infarcted myocardium in mice

BACKGROUND

Bone-marrow-derived progenitor cells are important in myocardial repair mechanisms following prolonged ischemia. Cell-based therapy of diseased myocardium is limited by a low level of tissue engraftment.

OBJECTIVES

The aim of this study was the development of the bifunctional protein αCD133-glycoprotein (GP)VI as an effective treatment for supporting vascular and myocardial repair mechanisms.

RESULTS

We have generated and characterized a bifunctional molecule (αCD133-GPVI) that binds both to the subendothelium of the injured microvasculature and to CD133(+) progenitor cells with high affinity. αCD133-GPVI enhances progenitor cell adhesion to extracellular matrix proteins and differentiation into mature endothelial cells. In vivo studies showed that αCD133-GPVI favors adhesion of circulating progenitor cells to the injured vessel wall (intravital microscopy). Also, treatment of mice undergoing experimental myocardial infarction with αCD133-GPVI-labeled progenitor cells reduces infarction size and preserves myocardial function.

CONCLUSIONS

The bifunctional trapping protein αCD133-GPVI represents a novel and promising therapeutic option for limiting heart failure of the ischemic myocardium.