Supervisor: Mgr. Miroslav Boudny, Ph.D.
The inhibition of BCR-associated kinases by so-called B cell receptor signalling inhibitors in B cell leukemia and lymphomas is a potent therapeutic strategy, and several BTK and PI3K kinase inhibitors are available for clinical use (Ondrisova and Mraz, 2020). Arguably, the therapy with BTK/PI3K inhibitors is the most promising therapeutic approach in chronic lymphocytic leukemia (CLL). However, the typically good initial clinical effect in great majority of cases is later followed by a relapse or drug intolerance. Notably, the “BCR inhibitors” lead to the accumulation of CLL cells in the peripheral blood, which undergo apoptosis at a surprisingly slow rate with a peripheral blood lymphocytosis lasting for several months (Ondrisova and Mraz, 2020). This is in contrast to studies of normal B cells in mouse models where ablation of BCR receptor (largely analogical to BTK inhibition) results in quick (days) disappearance of all mature B cells. The key questions are: Are there adaptation mechanisms that allow CLL cells to survive in the peripheral blood when BCR signalling and their re-circulation to immune niches is inhibited by BTK/PI3K inhibitors? The long-lasting lymphocytosis during therapy with ibrutinib or idelalisib as single agents suggests that malignant B cells adapt and compensate for „BCR inhibition”, and this might be later followed by occurrence of mutations that provide true resistance such as the selection of clones with BTK mutations, or other aberrations.
Based on our preliminary data we have identified two novel mechanisms that CLL cells utilize in vivo to survive BTK inhibition by ibrutinib, and we propose 3 novel targeted combinatorial therapeutic strategies with BCR inhibitors. The aim of the project is to reveal the molecular mechanisms that specifically allow adaptation to the BCR inhibitors or their combinations with other drugs such as anti-CD20 or venetoclax (BCL2 inhibitor). The primary samples collected before and during therapy will be analyzed on the level of protein and RNA expression (NGS with Illumina, preliminary data available). This will be followed by searching for function to better understand the disease biology and possibly to identify novel therapeutic targets. Project applies technics such as genome editing (CRISPR), RNA sequencing, use of primary samples, functional studies with various in vitro and in vivo models.
- Seda et al. FoxO1-GAB1 Axis Regulates Homing Capacity and Tonic AKT Activity in Chronic Lymphocytic Leukemia. Blood 2021 March (epub). https://pubmed.ncbi.nlm.nih.gov/33786575/
- Pavlasova G, Borsky M, Svobodova V, Oppelt J, Cerna K, Novotna J, Seda V, Fojtova M, Fajkus J, Brychtova Y, Doubek M, Pospisilova S, Mayer J, Mraz M. Rituximab primarily targets an intra-clonal BCR signaling proficient CLL subpopulation characterized by high CD20 levels. Leukemia. 2018 Sep;32(9):2028-2031. doi: 10.1038/s41375-018-0211-0.
- Pavlasova G, Borsky M, Seda V, Cerna K, Osickova J, Doubek M, Mayer J, Calogero R, Trbusek M, Pospisilova S, Davids MS, Kipps TJ, Brown JR, Mraz M. Ibrutinib inhibits CD20 upregulation on CLL B cells mediated by the CXCR4/SDF-1 axis. Blood. 2016 Sep 22;128(12):1609-13.
For additional information on our research please go to https://www.ceitec.eu/microenvironment-of-immune-cells-marek-mraz/rg115.
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