Sustained Brown Fat Stimulation and Insulin Sensitization by a Humanized Bispecific Antibody Agonist for Fibroblast Growth Factor Receptor 1/βKlotho Complex

Abstract

Dissipating excess calories as heat through therapeutic stimulation of brown adipose tissues (BAT) has been proposed as a potential treatment for obesity-linked disorders. Here, we describe the generation of a humanized effector-less bispecific antibody that activates fibroblast growth factor receptor (FGFR) 1/βKlotho complex, a common receptor for FGF21 and FGF19. Using this molecule, we show that antibody-mediated activation of FGFR1/βKlotho complex in mice induces sustained energy expenditure in BAT, browning of white adipose tissue, weight loss, and improvements in obesity-associated metabolic derangements including insulin resistance, hyperglycemia, dyslipidemia and hepatosteatosis. In mice and cynomolgus monkeys, FGFR1/βKlotho activation increased serum high-molecular-weight adiponectin, which appears to contribute over time by enhancing the amplitude of the metabolic benefits. At the same time, insulin sensitization by FGFR1/βKlotho activation occurs even before the onset of weight loss in a manner that is independent of adiponectin. Together, selective activation of FGFR1/βKlotho complex with a long acting therapeutic antibody represents an attractive approach for the treatment of type 2 diabetes and other obesity-linked disorders through enhanced energy expenditure, insulin sensitization and induction of high-molecular-weight adiponectin.

A Fibroblast Growth Factor 21–Pregnane X Receptor Pathway Downregulates Hepatic CYP3A4 in Nonalcoholic Fatty Liver Disease

“…These findings are consistent with the relative absence of FGFR1c receptors in adult mouse liver, despite abundantly expressed bKlotho coreceptor (Fon Tacer et al, 2010). Furthermore, an FGFR1c-bKlotho bispecific agonistic antibody was able to activate adipose tissue ERK1/2 but not in liver (Kolumam et al, 2015). Thus, it is considered that several effects of FGF21 on glucose homeostasis, insulin sensitivity, and hepatic steatosis may occur indirectly through stimulation of adiponectin secretion in adipocytes (Lin et al, 2013) or by actions initiated in the central nervous system (Bookout et al, 2013).…”

“…Thus, it is considered that several effects of FGF21 on glucose homeostasis, insulin sensitivity, and hepatic steatosis may occur indirectly through stimulation of adiponectin secretion in adipocytes (Lin et al, 2013) or by actions initiated in the central nervous system (Bookout et al, 2013). However, other studies demonstrated rapid hepatic ERK1/2 phosphorylation in mice after pharmacological administration of FGF21 and in isolated hepatocytes treated with FGF21, suggesting direct effects on the liver (Fisher et al, 2011;Jiang et al, 2014;Kolumam et al, 2015). Indeed, we observed enhanced ERK1/2 phosphorylation in mouse livers overexpressing FGF21 (Fig.…”

FGF21-receptor agonists: an emerging therapeutic class for obesity-related diseases

“…This activity was attributed to an increase in Glut1 mRNA and protein expression [14]. In addition, FGF21 and FGF21RA induce expression of Uncoupling protein 1 (Ucp1) mRNA in cultured primary adipocytes [27], [35], [36], [37], which may play a role in inducing white adipose tissue "browning" in mice [27], [38]. At the target tissues, receptor activation by FGF21 triggers a transcriptional response of various genes, including Ucp1 upregulation in adipose tissues [15], [16].…”

“…The rat L6 cell system provides a lower degree of luciferase induction as compared with HEK293 but is more suitable for measuring receptor specificity due to the lack of endogenous FGFR expression [34]. These reporter assays as well as a direct measurement of ERK phosphorylation have been widely used to test and screen various FGF21RAs as well as FGFR4-sparing FGF19 analogs [27], [33], [34], [41], [45].…”

“…While many of the transcriptional responses are tissue-type specific and may be driven by indirect effects, several genes induced by FGF21 are not restricted by cell type and likely represent proximal target downstream of FGFR. These genes include Sprouty 4 (Spry4) and Dual specificity phosphatase 4 and 6 (Dusp4 and Dusp6), the known negative feedback regulators of FGFR [8], [27], [39], [40]. Determining the induction of these genes in tissue biopsies could serve as proximal FGF21 pathway biomarkers in preclinical and clinical settings.…”