Table of Contents

Aims

Understanding specific recognition of tumor cells by T cells and developing tools for immunotherapy / diagnosis

Background

T lymphocytes can recognize and specifically kill tumor cells by recognizing HLA-peptide complexes through their T cell receptor. We are focusing on the identification of antigens and their respective HLA epitopes.

On tumor entity we are working on is malignant melanoma, a tumor originating from neuroectodermal cells, the melanocytes. Melanoma is a fast progressing tumor highly resistant to many therapies and is known to be very immunogenic, likewise a number of different antigens are well known. Still, the immune response of the patient often is not able to eliminate all tumor cells. As in some other types of cancer, immune responses against melanoma also can induce paraneoplastic syndromes. On the other hand, the tumor can counteract immune responses by various means, e.g. by delivering cytokines or specific miRNAs.

The present work in our group is focusing on the following topics dealing one or the other way with the interplay between skin tumor and immune system.

Projects

The following projects are currently running in our group. The references in brackets are refering to the publication list (see left side, publications).

Project 1: Development of NY-BR-1 derived vaccine for breast cancer

NY-BR-1 is a tumor-antigen strongly overexpressed in breast cancer [1-3] and thus represents a suitable target antigen for immunotherapy. Presently, only two HLA-A2-restricted CTL epitopes have been identified which will soon be used in a clinical trial [4]. The aims of this project are (1) to broaden the spectrum of T cell epitopes for clinical usage, (2) to identify class II epitopes for the optimization of immunological therapy approaches, and (3) to test different therapeutic strategies in preclinical mouse models.
This project will utilize HLA-transgenic mice and peptide libraries to screen for HLA-restricted CTL- and T-helper epitopes [5]. As a second step, PBMCs from tumor patients will be analyzed for the presence of specific T cells against the identified epitopes and these cells will be expanded and tested for a number of markers defining T cell subtype and activation status. Antigen-specificity and cytolytic capacity will be tested by ELISPOT, Tetramer and chromium release assay on breast cancer cell lines and transduced target cells in vitro and in vivo. Finally, different vaccination protocols will be tested in order to raise and expand NY-BR-1 specific T cell lines for curative adoptive T cell transfer of various tumor bearing mouse strains.

This is a collaborative project with Prof. Dr. Dirk Jäger and Dr. Inka Zoernig, NCT Heidelberg.

Refs:
1) Jäger D et al. (2001) Cancer Res 61: 2055-61.
2) Seil I et al. (2007) Int J Cancer 120: 2635-42.
3) Theurillat JP et al. (2007) Cancer Immunol Immunother 56: 1723-31.

Project 2: Cancer-retina antigens as therapeutic targets for immunotherapy

We have recently described a new class of tumor antigens, called cancer-retina antigens (CRA), which are expressed in melanoma [1] and pancreatic cancer (unpublished), and which can elicit humoral and cellular immune responses. The aim of this project is to (1) identify immunogenic, HLA-restricted T cell epitopes of these CRA, (2) generate CRA-specific T cells and (3) test their therapeutic efficiency in mouse models either on transplanted tumors or in transgenic mice with spontaneous tumor formation (melanoma model and pancreatic cancer model) [2]. The project will utilize HLA-transgenic mice and peptide libraries to screen for HLA-restricted T cell epitopes presented by class I and class II molecules [3]. Using computational algorithms and synthetic candidate peptides the precise epitopes will be determined. As a second step, PBMCs from tumor patients will be analyzed for the presence of specific T cells against the identified epitopes and these cells will be expanded and tested for a number of markers defining T cell subtype and activation status. Specificity and cytolytic capacity will be tested by ELISPOT, Tetramer and chromium release assay respectively using pancreatic cancer cell lines and transduced cells as targets. Finally, both generated CRA-specific T-cells and long peptides will be tested in therapeutical and preventive setting in melanoma and pancreatic cancer animal tumor models.

This is a collaborative project with PD Dr. Alexandr Bazhin, Dept. of Surgery, University Hospital Heidelberg.

1)Bazhin AV, Schadendorf D, Willner N, De Smet C, Heinzelmann A, Tikhomirova NK, Umansky V, Philippov PP, and Eichmüller SB (2007) Int J Cancer 120: 1268-1276.
2) Kimpfler S, Sevko A, Ring S, Falk C, Osen W, Frank K, Kato M, Mahnke K, Schadendorf D, and Umansky V (2009) J Immunol
3) Paschen A, Song M, Osen W, Nguyen XD, Mueller-Berghaus J, Fink D, Daniel N, Donzeau M, Nagel W, Kropshofer H, and Schadendorf D (2005) Clin Cancer Res 11: 5241-5247.
4) Märten A, Büchler MW. Curr Opin Investig Drugs 2008;9:565-569.

Project 3: Analyzing humoral immune responses in cancer patients as prognostic tool

During the studies performed in the last years, we and others could show that tumor patients exhibit a humoral response to a variety of antigens associated with their tumor. They do so even when these antigens are not expressed in a tumor-specific fashion (autoantibodies). In a study using sera from melanoma patients, we found that immunotherapy can induce such responses. Also CTCL patients often displayed autoantibodies even though the vaccine did not contain the antigen targeted by these antibodies. On the other hand, patients exhibit autoantibodies even without therapy, which may indicate an already mounted immune response against the tumor. Sometimes, these immune responses can cause paraneoplastic syndromes. In this project we analyze on a large scale the specificity and sensitivity of autoantibody responses in tumor patients and healthy controls using the LUMINEX approach. One aim of these analyses is to get a measure for predicting therapy responses and thus allowing the physician to decide on promising, individual therapy. Following autoantibody responses during therapy is an option for additional monitoring information.

This is a collaborative project with Prof. Dr. Dirk Jäger and PD Dr. Christine Falk, NCT Heidelberg.

Project 4: non-coding RNAs in melanoma

Non-coding RNAs like microRNA are meanwhile recognized for their widespread functions in various biological processes as well as in cancer development. The aim of this project is to identify ncRNAs which are specific for melanoma and may be associated with the aggressiveness. ncRNAs may account for tumor responses against the patients' immune defense, as well as direct interaction with the stroma.
A special focus lies on the identification of miRNAs impacting on migration and invasion of melanoma cells. This project is part of the "Melanoma Research Network" and funded by the German Cancer Aid.

Cooperations

• Prof. Dr. Peter Altevogt (same department)
• PD Dr. Alexandr Bazhin (Dept. Surgery, University Hospital Heidelberg)
• Prof. Dr. Philipp Beckhove (same department)
• Dr. Sven Diederichs (DKFZ, B150)
• Prof. Dr. Reinhard Dummer (Dermatology, Zürich)
• PD Dr. Christine Falk (Hannover Medical School)
• Prof. Dr. Graw & Dr. Dalke (GSF, Munich)
• Prof. Dr. Sinisa Grozdanik (Iowa State Univ, USA)
• Prof. Dr. Ali Güre (Bilkent University, Ankara, Turkey)
• Prof. Dr. Bruno Kyewski (DKFZ, D090)
• Prof. Dr. Dirk Jäger (NCT Heidelberg)
• Dr. Michael Pawlita (DKFZ,F020)
• PD Dr. Annette Paschen (University Hospital Essen)
  
• Prof. Dr. Pavel Philippov (Moscow State University, Russia)
• PD Dr. Reinhard Schwartz-Albiez (same department)
• Prof. Dr. Viktor Umansky (DKFZ, G300)

References & Links