KIT V560G

Pathway analysis identified increased oxidative phosphorylation in D816V- and V560G-mutant KIT cells, which was targetable using the inhibitor IACS010759...Phosphoproteome analysis further revealed active kinases such as EGFR, ERK and PKC, which were targetable using pharmacological inhibitors. This study provides a pharmaco-phosphoproteomic profile of D816V- and V560G-mutant KIT cells, which reveals novel therapeutic strategies that may be applicable to a range of cancers.

Accordingly, proliferation assays revealed that KIT mutant FDC-P1 cells were more sensitive to the DNA-PK inhibitors M3814 or NU7441, compared with empty vector controls. DNA-PK inhibition combined with inhibition of KIT signaling using the kinase inhibitors dasatinib or ibrutinib, or the protein phosphatase 2A activators FTY720 or AAL(S), led to synergistic cell death...Combined dasatinib and M3814 treatment also synergistically inhibited phosphorylation of the transcriptional regulators MYC and MYB. This study provides insight into the oncogenic pathways regulated by DNA-PK beyond its canonical role in DNA repair, and demonstrates that DNA-PK is a promising therapeutic target for KIT mutant cancers.

We observed that low concentrations of the TKIs Nilotinib and Ponatinib resulted in enhanced proliferation, suggesting paradoxical activation of the MAPK pathway...The combination of Ponatinib with the MEK inhibitor Trametinib, at nanomolar concentrations, effectively suppressed HMC-1.2 proliferation, metabolic activity, and induced apoptotic cell death...Effectiveness of this drug combination was recapitulated in the human KIT D816V MC line ROSA and in KIT D816V hematopoietic progenitors obtained from patient-derived induced pluripotent stem cells (iPS cells) and systemic mastocytosis patient samples. In conclusion, mutated KIT-driven Imatinib resistance and possible TKI-induced paradoxical activation can be efficiently overcome by a low concentration Ponatinib and Trametinib co-treatment, potentially reducing the negative side effects associated with MCL therapy.

Although the recently approved poly tyrosine kinase inhibitor Midostaurin provides some improvement, the median overall survival ranges from 3.5 years (ASM) to less than six months (MCL)...However, as CAR T-cells are highly efficient, collateral damage on healthy HSPCs will likely need to be compensated by subsequent HSC transplantation. We are currently translating these promising in vitro immunotherapeutic settings into surrogate xenogeneic in vivo models.

In AML, KIT mislocalizes to EL. Our findings, however, suggest that the mutant transduces phosphorylation signals on lipid rafts of the Golgi in leukemia cells. Unexpectedly, the KIT signal platform in MCL is similar to that of KIT in AML. These observations provide new insights into the pathogenic role of KIT mutants as well as that of other mutant molecules.