Asunto(s)
Resistencia a Antineoplásicos , Proteínas de Fusión bcr-abl , Isoformas de Proteínas , Humanos , Proteínas de Fusión bcr-abl/genética , Resistencia a Antineoplásicos/genética , Isoformas de Proteínas/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Inhibidores de Proteínas Quinasas/uso terapéutico , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-abl/genética , Proteínas Proto-Oncogénicas c-abl/metabolismo , Niacinamida/análogos & derivados , PirazolesRESUMEN
ABSTRACT: Secondary kinase domain mutations in BCR::ABL1 represent the most common cause of resistance to tyrosine kinase inhibitor (TKI) therapy in patients with chronic myeloid leukemia. The first 5 approved BCR::ABL1 TKIs target the adenosine triphosphate (ATP)-binding pocket. Mutations confer resistance to these ATP-competitive TKIs and those approved for other malignancies by decreasing TKI affinity and/or increasing ATP affinity. Asciminib, the first highly active allosteric TKI approved for any malignancy, targets an allosteric regulatory pocket in the BCR::ABL1 kinase C-lobe. As a non-ATP-competitive inhibitor, the activity of asciminib is predicted to be impervious to increases in ATP affinity. Here, we report several known mutations that confer resistance to ATP-competitive TKIs in the BCR::ABL1 kinase N-lobe that are distant from the asciminib binding pocket yet unexpectedly confer in vitro resistance to asciminib. Among these is BCR::ABL1 M244V, which confers clinical resistance even to escalated asciminib doses. We demonstrate that BCR::ABL1 M244V does not impair asciminib binding, thereby invoking a novel mechanism of resistance. Molecular dynamic simulations of the M244V substitution implicate stabilization of an active kinase conformation through impact on the α-C helix as a mechanism of resistance. These N-lobe mutations may compromise the clinical activity of ongoing combination studies of asciminib with ATP-competitive TKIs.
Asunto(s)
Resistencia a Antineoplásicos , Proteínas de Fusión bcr-abl , Leucemia Mielógena Crónica BCR-ABL Positiva , Inhibidores de Proteínas Quinasas , Humanos , Resistencia a Antineoplásicos/genética , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas de Fusión bcr-abl/genética , Proteínas de Fusión bcr-abl/química , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Mutación , Adenosina Trifosfato/metabolismo , Proteínas Proto-Oncogénicas c-abl/genética , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas c-abl/química , Niacinamida/análogos & derivados , PirazolesRESUMEN
Signal-regulatory protein α (SIRPα) expressed by myeloid cells is of particular interest for therapeutic strategies targeting the interaction between SIRPα and the "don't eat me" ligand CD47 and as a marker to monitor macrophage infiltration into tumor lesions. To address both approaches, we developed a set of novel human SIRPα (hSIRPα)-specific nanobodies (Nbs). We identified high-affinity Nbs targeting the hSIRPα/hCD47 interface, thereby enhancing antibody-dependent cellular phagocytosis. For non-invasive in vivo imaging, we chose S36 Nb as a non-modulating binder. By quantitative positron emission tomography in novel hSIRPα/hCD47 knock-in mice, we demonstrated the applicability of 64Cu-hSIRPα-S36 Nb to visualize tumor infiltration of myeloid cells. We envision that the hSIRPα-Nbs presented in this study have potential as versatile theranostic probes, including novel myeloid-specific checkpoint inhibitors for combinatorial treatment approaches and for in vivo stratification and monitoring of individual responses during cancer immunotherapies.