HER2 mediates clinical resistance to the KRAS inhibitor sotorasib, which is overcome by co-targeting SHP2.

INTRODUCTION

Mutant RAS guanosine triphosphate hydrolases (GTPases) are key oncogenic drivers in many cancers. The KRAS variant has recently become targetable by a new drug class specifically locking KRAS in its inactive guanosine diphosphate (GDP)-bound state. Clinical activity was demonstrated in patients with advanced lung cancers harbouring KRAS mutations but was limited by the development of resistance.

METHODS

A biopsy from progressing lung cancer of a patient treated with the KRAS inhibitor sotorasib was obtained, and the underlying resistance factors were analysed. Mechanistic studies were performed in vitro and in vivo to uncover strategies to overcome resistance to KRAS inhibition.

RESULTS

We demonstrated acquisition of HER2 copy number gain and KRAS mutation retention in the post-progression biopsy. To explore HER2 gain as the relevant resistance mechanism, we generated KRAS lung cancer models overexpressing HER2. MAPK pathway signalling remained active despite KRAS inhibitor treatment. Combined pharmacological inhibition of KRAS and SHP2 synergistically overcame HER2-mediated resistance in vitro and in vivo.

CONCLUSIONS

These findings establish HER2 copy number gain as a clinically relevant mechanism of resistance to pharmacological KRAS inhibition that can be overcome by co-targeting SHP2.