Design, synthesis, and evaluation of dual EGFR/AURKB inhibitors as anticancer agents for non-small cell lung cancer

Abstract

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are first-line agents for mutant EGFR-positive (mEGFR+) NSCLC. However, secondary resistant mutations develop following therapy that prevent EGFR-TKI binding. The EGFR-TKIs are rendered ineffective in NSCLC expressing EGFR resistant mutations (rmEGFR+). Mutations in Kirsten rat sarcoma virus protein (mKRAS) support persistent signaling downstream of EGFR regardless of EGFR-TKI earlier in the signaling cascade. The EGFR-TKIs are ineffective in mKRAS+ NSCLC. Thus, newer anticancer agents are needed for rmEGFR+ and mKRAS+ NSCLC. Aurora kinase B (AURKB) is a mitosis related kinase that is overexpressed in NSCLC and supports cancer cell proliferation and survival. Literature reports have suggested that AURKB inhibitors if given concurrently with an EGFR-TKI could overcome EGFR-TKI resistance in mKRAS+ NSCLC and rmEGFR + NSCLC, and showed improved anticancer effects compared to current single-targeted EGFR-TKIs. Molecular modeling was used to identify similarities between the kinase pockets of EGFR and AURKB. An overlap was observed for the inactive conformation of EGFR and the active conformation of AURKB. Compounds 3-7 were synthesized as dual EGFR/AURKB inhibitors for mKRAS+ and rmEGFR+ NSCLC. Compounds 5, 6 and 7 were identified as dual EGFR/AURKB inhibitors. Compound 5 demonstrated modest micromolar inhibition of rmEGFR+ NSCLC. All investigated compounds showed moderate inhibition of mKRAS+ NSCLC cells. Compound 7 demonstrated single-digit micromolar inhibition of mKRAS+ NSCLC.

Keywords: Aurora kinase; Epidermal growth factor receptor kinase; Lung cancer; Resistance.

Fig. 1.

Kinase inhibitors targeting EGFR or AURKB.

Fig. 2.

Neratinib (grey) bound to the extended conformation of EGFR (green) overlays on barasertib (purple) bound to the extended conformation of AURKB (orange). An overlap is observed for interactions with the backbone amino acids in the hinge region, adenine region, hydrophobic region I and the back pocket for EGFR and AURKB.

Fig. 3.

Target compounds.

Fig. 4.

Left panel: Docked poses for compounds 1–7 and barasertib (white) within the extended conformation of AURKB (pink). Compounds 1–7 demonstrated consistent modes of binding within AURKB; Right panel: Docked poses for compounds 1–7 and neratinib (white) within the inactive, αC-helix out conformation of EGFR (grey). The 4-substitution in compounds 1, 2 did not extend in to the αC-helix out pocket. Compounds 3, 6 and 7 occupied the αC-helix out pocket of EGFR. The 4-substitution in 4 and 5 was oriented toward the solvent.

Fig. 5.

Left panel: Compound 7 (orange) overlaid on AEE788 (brown) within active EGFR (green) showing interactions with the hinge region and the ATP pocket for the pyrrolo[2,3-d]pyrimidine scaffold and the 6-substitution, and for the 4-benzyloxy sidechain within hydrophobic region I of the front cleft. Right panel: Compound 7 (orange) overlaid on neratinib (grey) within inactive EGFR (grey) showing interactions with the hinge region and the ATP pocket for the pyrrolo[2,3-d]pyrimidine scaffold and the 6-substitution, and for the 4-benzyloxy sidechain within the αC-helix out pocket. Compound 7 is accommodated in the active and inactive conformation of EGFR.

Fig. 6.

Left panel: Compound 5 (cyan) overlaid on ZM447439 (white) within AURKB showing interactions in the ATP pocket and back pocket and an overlap with ZM447439.; Right panel: Compound 5 (cyan) does not overlay on neratinib (grey) within EGFR. The 4-substitution is oriented towards the solvent instead of the αC-helix out pocket. Compound 5 binds in different modes to EGFR and AURKB.

Fig. 7.

Left panel: Compound 6 (brown) overlaid on ZM447439 (white) within AURKB showing interactions in the ATP pocket and back pocket.; Right panel: Compound 7 (green) overlaid on ZM447439 (white) within AURKB showing a similar mode of binding within AURKB as seen for EGFR with interactions in the ATP pocket and the αC-helix out pocket of EGFR. Compounds 6 and 7 bind in a similar mode to ZM447439 within AURKB.

Fig. 8.

Kinase interaction plot for 5 (left panel), 6 (middle panel) and 7 (right panel).

Scheme 1.

Synthesis of compounds 3–7.