Dynamics of the tumor infiltrating lymphocyte repertoire in melanoma and pancreatic cancer
In many types of cancer the presence of tumor-infiltrating lymphocytes (TIL) is associated with better survival. This suggests that the immune system can recognize and fight tumors. In advanced cancer the dominant scenario is often one of immunosuppression, where for example TIL are rendered impotent through inhibitory factors secreted by tumor cells.
Therapeutic efforts aim to revert this situation, e.g. by blocking negative signals using therapeutic antibodies (e.g. Ipilimumab). The in vitro expansion and re-infusion of TIL (so called TIL therapy) can also (re)activate the anti-tumoral immune response.
Under such optimized circumstances the inhibition of tumor growth by the immune system can be remarkable, even in metastatic cancer. This has been studied particularly well in patients with malignant melanoma. Many studies have shown that the success of such therapies depends on the presence of tumor-reactive T-cells. However, it is not yet fully understood exactly which T-cells are responsible for mediating these positive effects.
The TIL-REP consortium will investigate the composition and dynamic changes of the TIL repertoire as well as its clinical implications. To this end we are pursuing three complimentary approaches:
- Analysis of the TIL repertoire in human tumor biopsies of melanoma and pancreatic ductal adenocarcinoma by phenotypic characterization (measurement of characteristic cell surface and activation markers) and T-cell receptor (TCR) sequencing (see Fig. 1)
- Examination of the clonal dynamics of the TIL response in a well-defined pre-clinical model
- Establishment of a data-driven mathematical model to quantify and thus better understand the fundamental processes governing the development of the TIL repertoire and simulate its response to immunotherapy
Our systems medicine approach (see Fig 2) combines data from mathematical models, pre-clinical experiments and patient-based research to better understand tumor-immune interactions, develop biomarkers for immunotherapy trials and improve cancer patient care.
To achieve these goals we are working in an interdisciplinary team, allowing us to address our research questions from a theoretical, (cell)biological and clinical perspective (see Fig 3).
Subprojects in TIL-REP:
Keywords: tumor-infiltrating lymphocytes, immunotherapy, T-cell receptor repertoire, next-generation sequencing, pancreatic cancer, melanoma, vaccination, immuno-stimulatory antibodies