Introduction of small-molecule inhibitors of B-cell receptor signaling and BCL2 protein significantly improves therapeutic options in chronic lymphocytic leukemia. However, some patients suffer from adverse effects mandating treatment discontinuation, and cases with TP53 defects more frequently experience early progression of the disease. Development of alternative therapeutic approaches is, therefore, of critical importance. Here we report details of the anti-chronic lymphocytic leukemia single-agent activity of MU380, our recently identified potent, selective, and metabolically robust inhibitor of checkpoint kinase 1. We also describe a newly developed enantioselective synthesis of MU380, which allows preparation of gram quantities of the substance. Checkpoint kinase 1 is a master regulator of replication operating primarily in intra-S and G2/M cell cycle checkpoints. Initially tested in leukemia and lymphoma cell lines, MU380 significantly potentiated efficacy of gemcitabine, a clinically used inducer of replication stress. Moreover, MU380 manifested substantial single-agent activity in both TP53-wild type and TP53-mutated leukemia and lymphoma cell lines. In chronic lymphocytic leukemia-derived cell lines MEC-1, MEC-2 (both TP53-mut), and OSU-CLL (TP53-wt) the inhibitor impaired cell cycle progression and induced apoptosis. In primary clinical samples, MU380 used as a single-agent noticeably reduced the viability of unstimulated chronic lymphocytic leukemia cells as well as those induced to proliferate by anti-CD40/IL-4 stimuli. In both cases, effects were comparable in samples harboring p53 pathway dysfunction (TP53 mutations or ATM mutations) and TP53-wt/ATM-wt cells. Lastly, MU380 also exhibited significant in vivo activity in a xenotransplant mouse model (immunodeficient strain NOD-scid IL2Rγnull ) where it efficiently suppressed growth of subcutaneous tumors generated from MEC-1 cells.

• MeSH
• apoptóza MeSH
• buněčný cyklus MeSH
• checkpoint kinasa 1 antagonisté a inhibitory   MeSH
• chemorezistence účinky léků   MeSH
• chronická lymfatická leukemie farmakoterapie   genetika   patologie   MeSH
• deoxycytidin analogy a deriváty   farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• mutace * MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši MeSH
• nádorové biomarkery genetika   MeSH
• nádorové buňky kultivované MeSH
• nádorový supresorový protein p53 genetika   MeSH
• piperidiny farmakologie   MeSH
• proliferace buněk MeSH
• protinádorové antimetabolity farmakologie   MeSH
• pyrazoly farmakologie   MeSH
• pyrimidiny farmakologie   MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• synergismus léků * MeSH
• xenogenní modely - testy protinádorové aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Treatment options for TP53-mutated lymphoid tumors are very limited. In experimental models, TP53-mutated lymphomas were sensitive to direct inhibition of checkpoint kinase 1 (Chk1), a pivotal regulator of replication. We initially tested the potential of the highly specific Chk1 inhibitor SCH900776 to synergize with nucleoside analogs (NAs) fludarabine, cytarabine and gemcitabine in cell lines derived from B-cell malignancies. In p53-proficient NALM-6 cells, SCH900776 added to NAs enhanced signaling towards Chk1 (pSer317/pSer345), effectively blocked Chk1 activation (Ser296 autophosphorylation), increased replication stress (p53 and γ-H2AX accumulation) and temporarily potentiated apoptosis. In p53-defective MEC-1 cell line representing adverse chronic lymphocytic leukemia (CLL), Chk1 inhibition together with NAs led to enhanced and sustained replication stress and significantly potentiated apoptosis. Altogether, among 17 tested cell lines SCH900776 sensitized four of them to all three NAs. Focusing further on MEC-1 and co-treatment of SCH900776 with fludarabine, we disclosed chromosome pulverization in cells undergoing aberrant mitoses. SCH900776 also increased the effect of fludarabine in a proportion of primary CLL samples treated with pro-proliferative stimuli, including those with TP53 disruption. Finally, we observed a fludarabine potentiation by SCH900776 in a T-cell leukemia 1 (TCL1)-driven mouse model of CLL. Collectively, we have substantiated the significant potential of Chk1 inhibition in B-lymphoid cells.

• MeSH
• apoptóza MeSH
• B-lymfocyty cytologie   MeSH
• buněčný cyklus MeSH
• checkpoint kinasa 1 antagonisté a inhibitory   MeSH
• chronická lymfatická leukemie farmakoterapie   genetika   metabolismus   MeSH
• cytarabin aplikace a dávkování   MeSH
• deoxycytidin aplikace a dávkování   analogy a deriváty   MeSH
• lidé MeSH
• mitóza MeSH
• mutace MeSH
• myši transgenní MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nukleosidy genetika   MeSH
• proliferace buněk MeSH
• pyrazoly farmakologie   MeSH
• pyrimidiny farmakologie   MeSH
• screeningové testy protinádorových léčiv MeSH
• signální transdukce MeSH
• viabilita buněk MeSH
• vidarabin aplikace a dávkování   analogy a deriváty   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH