|Ph.D Student||Hod Marco Moran|
|Subject||System Analysis of the Functional Fate of Tumor|
|Department||Department of Biology||Supervisors||Professor Yoram Reiter|
|Dr. Michal Besser|
|Full Thesis text|
Tumor infiltrating lymphocytes (TILs) are a heterogeneous population of immune cells with potential anti-tumor reactivity. In the clinic, TILs are used for a therapeutic strategy of adoptive cell transfer (ACT), for stage IV metastatic melanoma patients. In this treatment, TILs are isolated from the patient tumor, expanded ex-vivo based on a process of rapid expansion (REP) to generate the final product that is administered back to the patient. Despite the clinical success of ACT and the extensive research in the field, little is known about the alterations that occur in TILs during the REP process and its influence on TIL anti-tumor function. In previous studies we have shown that the subpopulation composition of a TIL culture dictates its anti-tumor response; however, there is insufficient knowledge on the key molecular mechanisms that interconnect subpopulation compositions with functional outcome of TIL anti-tumor reactivity. Using multi-parametric flow cytometry, computational tools and functional assays (IFN-γ release), we determined the influence of the expansion process on specific subpopulation frequencies, subpopulation signatures, and tumor reactivity of young TILs before and after REP. Analysis of pre-REP young TILs revealed distinctive subpopulation signatures which correlate significantly with reactivity or non-reactivity against melanoma. Importantly, pre-REP young TIL signatures share similarity in subpopulation composition and correlation with reactivity to signatures obtained in previous studies for pre-REP TILs that have been selected based on reactivity against melanoma. Further analysis of Pre vs. post-REP young TILs revealed that the REP induces alternations in subpopulation composition and thus, alterations in TIL reactivity and TIL subpopulation signatures. We found that Pre- and post-REP young TILs possess similar signatures for non-reactivity, but differ in the signatures for tumor reactivity. Interestingly, we found common features of post-REP reactive young TILs which are determined in their pre-REP state. Moreover, using RNA-seq and systems biology strategies to analyze whole genome transcriptome of TILs, we revealed specific gene signatures and key molecular pathways which are correlated with TIL reactivity.
In summary, this work presents new insights into major alterations in TIL properties and function induced by the expansion process which are important when using ACT and might help in selecting TILs with potential reactivity. Furthermore, we revealed important insights into the molecular mechanisms that dictate the functional fate of TILs which may be used for several types of manipulations to achieve optimal tumor reactivity of TILs or proper conditions for anti-tumor response.