Infigratinib low dose therapy is an effective strategy to treat hypochondroplasia

Hypochondroplasia is a rare genetic form of skeletal dysplasia, caused by gain-of-function pathogenic variants in the FGF receptor 3 (FGFR3). It is characterized by disproportionate short stature and has a wide spectrum of clinical features. Currently, there are no precision therapeutic options approved for hypochondroplasia. Infigratinib is an orally bioavailable FGFR1-3 selective tyrosine kinase inhibitor in development for achondroplasia and hypochondroplasia. Infigratinib acts directly at the source of the pathophysiological cause of both conditions by inhibiting the phosphorylation of FGFR3 and attenuating both main downstream signaling pathways that are involved in the conditions. Results from a phase 2 study support the concept that infigratinib has a potential to improve bone growth in achondroplasia. We report results of a step-wise evaluation of the therapeutic relevance of infigratinib for hypochondroplasia: in silico assessment of infigratinib with hypochondroplasia associated FGFR3 variants suggest strong interaction; in vitro, infigratinib showed potent inhibitory effect; in a mouse model of hypochondroplasia (Fgfr3N534K/+), infigratinib resulted in significant improvement in skeletal growth. These data in addition to the clinical results from the phase 2 study conducted in children with achondroplasia provide support for the development of infigratinib in the treatment of hypochondroplasia.