T-Cell Dynamics in Chronic Lymphocytic Leukemia under Different Treatment Modalities
Anna Vardi, Elisavet Vlachonikola, Despoina Papazoglou, Fotis Psomopoulos, Kostantia Kotta, Nikolaos Ioannou, Chrysi Galigalidou, Katerina Gemenetzi, Kostantinos Pasentsis, Maria Th. Kotouza, Evdoxia Koravou, Lydia Scarfó, Michail Iskas, Niki Stavroyianni, Paolo Ghia, Αchilles Anagnostopoulos, Anastasia Kouvatsi, Alan G. Ramsay, Κώστας Σταματόπουλος, Anastasia Chatzidimitriou
Abstract
PURPOSE: Using next-generation sequencing (NGS), we recently documented T-cell oligoclonality in treatment-naïve chronic lymphocytic leukemia (CLL), with evidence indicating T-cell selection by restricted antigens. EXPERIMENTAL DESIGN: Here, we sought to comprehensively assess T-cell repertoire changes during treatment in relation to (i) treatment type [fludarabine-cyclophosphamide-rituximab (FCR) versus ibrutinib (IB) versus rituximab-idelalisib (R-ID)], and (ii) clinical response, by combining NGS immunoprofiling, flow cytometry, and functional bioassays. RESULTS: T-cell clonality significantly increased at (i) 3 months in the FCR and R-ID treatment groups, and (ii) over deepening clinical response in the R-ID group, with a similar trend detected in the IB group. Notably, in constrast to FCR that induced T-cell repertoire reconstitution, B-cell receptor signaling inhibitors (BcRi) preserved pretreatment clones. Extensive comparisons both within CLL as well as against T-cell receptor sequence databases showed little similarity with other entities, but instead revealed major clonotypes shared exclusively by patients with CLL, alluding to selection by conserved CLL-associated antigens. We then evaluated the functional effect of treatments on T cells and found that (i) R-ID upregulated the expression of activation markers in effector memory T cells, and (ii) both BcRi improved antitumor T-cell immune synapse formation, in marked contrast to FCR. CONCLUSIONS: Taken together, our NGS immunoprofiling data suggest that BcRi retain T-cell clones that may have developed against CLL-associated antigens. Phenotypic and immune synapse bioassays support a concurrent restoration of functionality, mostly evident for R-ID, arguably contributing to clinical response.