LY2874455

LY2874455 is a novel and potent FGFR inhibitor with IC50 value of 7 nM [1].

Fibroblast growth factor receptors (FGFRs) are receptors bind ligand of FGF family, which have a intracellular domain with tyrosine kinase activity. The binding of FGF triggers receptor dimerization and thus the activation of tyrosine kinase activity. Activated tyrosine kinase phosphorylates various downstream factors to induce downstream signaling, including FGF substrate 2 (FGS2). This signaling pathway contributes to FGFR-mediated cell proliferation and migration, which are involved in tumor formation and progression.

In HUVECs cell line expressing FGFR1 and RT-112 cell line expressing FGFR3, LY2874455 treatment resulted in inhibition of FGF2 and FGF9 induced Erk phosphorylation, which indicated the inhibitory activity of LY2874455 for FGFR1 and FGFR3 [1]. In SNU-16 and KATO-Ш cell line, the inhibition of FGFR2 phosphorylation was also observed, which indicated a direct inhibition by LY2874455 [2]. Additionally, when several multiple myeloma cancer cell lines were treated with LYS2874455, the cell lines with chromosomal translocation that resulted in overexpression of FGFR3 were significantly more susceptible to the inhibition of LY2874455 [2]. It suggested FGFR was the specific target of LY2874455 inhibition.

In RT-112, SNU-16, OPM-2 and NCI-H460 xenograft tumor model, treatment of LY2874455 twice a day (1.5 mg/kg and 3 mg/kg) resulted in significant dose-dependent reduction of cellular level of phosphorylated FGFR, and also regression of tumor growth. It indicated the inhibitory activity of LY2874455 in vivo [2].

Reference:
[1] Zhao, G S et al. , A Novel, Selective Inhibitor of Fibroblast Growth Factor Receptors That Shows a Potent Broad Spectrum of Antitumor Activity in Several Tumor Xenograft Models. Molecular Cancer Therapeutics. 2011, 10(11): 2200-2210.

Acquired resistance to LY2874455 in FGFR2-amplified gastric cancer through an emergence of novel FGFR2-ACSL5 fusion.[Pubmed:28122360]

Oncotarget. 2017 Feb 28;8(9):15014-15022.

BACKGROUND: Fibroblast growth factor 2 (FGFR2) amplification, occurring in ~2-9% of gastric cancers (GC), is associated with poor overall survival. RESULTS: RNA sequencing identified a novel FGFR2-ACSL5 fusion in the resistant tumor that was absent from the matched pre-treatment tumor. The FGFR2-amplified PDC line was sensitive to FGFR inhibitors whereas the PDC line with concomitant FGFR2 amplification and FGFR2-ACSL5 fusion exhibited resistance. Additionally, the FGFR2-amplified GC PDC line, which was initially sensitive to FGFR2 inhibitors, subsequently also developed resistance. MATERIALS AND METHODS: We identified an FGFR2-amplified patient with GC, who demonstrated a dramatic and long-term response to LY2874455, a pan-FGFR inhibitor, but eventually developed an acquired LY2874455 resistance. Following resistance development, an endoscopic biopsy was performed for transcriptome sequencing and patient-derived tumor cell line (PDC) establishment to elucidate the underlying molecular alterations. CONCLUSIONS: FGFR inhibitors may function against FGFR2-amplified GC, and a novel FGFR2-ACSL5 fusion identified by transcriptomic characterization may underlie clinically acquired resistance. IMPLICATIONS FOR PRACTICE: Poor treatment response represents a substantial concern in patients with gastric cancer carrying multiple FGFR2 gene copies. Here, we show the utility of a general FGFR inhibitor for initial response prior to treatment resistance and report the first characterization of a potential resistance mechanism involving an FGFR2-ACSL5 fusion protein.

Crystal Structure of the FGFR4/LY2874455 Complex Reveals Insights into the Pan-FGFR Selectivity of LY2874455.[Pubmed:27618313]

PLoS One. 2016 Sep 12;11(9):e0162491.

Aberrant FGFR4 signaling has been documented abundantly in various human cancers. The majority of FGFR inhibitors display significantly reduced potency toward FGFR4 compared to FGFR1-3. However, LY2874455 has similar inhibition potency for FGFR1-4 with IC50 less than 6.4 nM. To date, there is no published crystal structure of LY2874455 in complex with any kinase. To better understand the pan-FGFR selectivity of LY2874455, we have determined the crystal structure of the FGFR4 kinase domain bound to LY2874455 at a resolution of 2.35 A. LY2874455, a type I inhibitor for FGFR4, binds to the ATP-binding pocket of FGFR4 in a DFG-in active conformation with three hydrogen bonds and a number of van der Waals contacts. After alignment of the kinase domain sequence of 4 FGFRs, and superposition of the ATP binding pocket of 4 FGFRs, our structural analyses reveal that the interactions of LY2874455 to FGFR4 are largely conserved in 4 FGFRs, explaining at least partly, the broad inhibitory activity of LY2874455 toward 4 FGFRs. Consequently, our studies reveal new insights into the pan-FGFR selectivity of LY2874455 and provide a structural basis for developing novel FGFR inhibitors that target FGFR1-4 broadly.