Multikinase activity of fibroblast growth factor receptor (FGFR) inhibitors SU5402, PD173074, AZD1480, AZD4547 and BGJ398 compromises the use of small chemicals targeting FGFR catalytic activity for therapy of short-stature syndromes

Abstract

Activating mutations in the fibroblast growth factor receptor 3 (FGFR3) cause the most common genetic form of human dwarfism, achondroplasia (ACH). Small chemical inhibitors of FGFR tyrosine kinase activity are considered to be viable option for treating ACH, but little experimental evidence supports this claim. We evaluated five FGFR tyrosine kinase inhibitors (TKIs) (SU5402, PD173074, AZD1480, AZD4547 and BGJ398) for their activity against FGFR signaling in chondrocytes. All five TKIs strongly inhibited FGFR activation in cultured chondrocytes and limb rudiment cultures, completely relieving FGFR-mediated inhibition of chondrocyte proliferation and maturation. In contrast, TKI treatment of newborn mice did not improve skeletal growth and had lethal toxic effects on the liver, lungs and kidneys. In cell-free kinase assays as well as in vitro and in vivo cell assays, none of the tested TKIs demonstrated selectivity for FGFR3 over three other FGFR tyrosine kinases. In addition, the TKIs exhibited significant off-target activity when screened against a panel of 14 unrelated tyrosine kinases. This was most extensive in SU5402 and AZD1480, which inhibited DDR2, IGF1R, FLT3, TRKA, FLT4, ABL and JAK3 with efficiencies similar to or greater than those for FGFR. Low target specificity and toxicity of FGFR TKIs thus compromise their use for treatment of ACH. Conceptually, different avenues of therapeutic FGFR3 targeting should be investigated.

Achondroplasia: Development, pathogenesis, and therapy

“…However, these TKIs are not selective for FGFR3 (Mohammadi et al, 1997; Dimitroff et al, 1999). Recently, NVP-BGJ398, a TKI more selective for FGFR3 over others FGFRs (Gudernova et al, 2016) was used in preclinical murine models for treating several FGFR-related cancers such as malignant rhabdoid tumors (Wohrle et al, 2013b), hepatocellular carcinoma (Scheller et al, 2015) and skeletal disorders including FGF23-mediated hypophosphatemic rickets (Wohrle et al, 2013a) and Ach (Komla-Ebri et al, 2016). Importantly, NVP-BGJ398 was shown in vivo to reduce FGFR3(p.Tyr367Cys) activation and improve the skeletal phenotype of Ach-like mice (Komla-Ebri et al, 2016).…”

FGFR3 is a positive regulator of osteoblast expansion and differentiation during zebrafish skull vault development

“…The alignment of the deduced amino acid sequence of zebrafish Fgfr3 with that of its human homolog (FGFR3) shows a high level of homology between the two proteins (77% overall, and more than 90% when considering the tyrosine kinase domain alone; Figure 1 -supplement 1). In order to investigate Fgfr3's role, we used the tyrosine kinase inhibitor BGJ398 (infigratinib, LC Laboratories) to block the factor's tyrosine kinase activity during cranial vault development (Gudernova et al, 2016;Komla-Ebri et al, 2016). Zebrafish larvae with a standard length (SL) of 7 mm (7SL) and expressing mCherry in osteoblasts (Tg(sp7: mCherry) were injected with BGJ398 every other day for 15 days ( Figure 1A).…”

Signaling pathways regulating cartilage growth plate formation and activity

“…A recent study showed that the efficacy of five small molecule FGFR inhibitors, while effective in chondrocytes in vitro , did not improve skeletal growth in mice. Troublingly, they had no selectivity for FGFR3, but had significant off-target activity for IGFR1 [43]. These data show that new innovative approaches to treat achondrodysplasia are still required.…”