From bench to bedside: current development and emerging trend of KRAS-targeted therapy

Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) is the most frequently mutated oncogene in human cancers with mutations predominantly occurring in codon 12. These mutations disrupt the normal function of KRAS by interfering with GTP hydrolysis and nucleotide exchange activity, making it prone to the GTP-bound active state, thus leading to sustained activation of downstream pathways. Despite decades of research, there has been no progress in the KRAS drug discovery until the groundbreaking discovery of covalently targeting the KRAS^G12C mutation in 2013, which led to revolutionary changes in KRAS-targeted therapy. So far, two small molecule inhibitors sotorasib and adagrasib targeting KRAS^G12C have received accelerated approval for the treatment of non-small cell lung cancer (NSCLC) harboring KRAS^G12C mutations. In recent years, rapid progress has been achieved in the KRAS-targeted therapy field, especially the exploration of KRAS^G12C covalent inhibitors in other KRAS^G12C-positive malignancies, novel KRAS inhibitors beyond KRAS^G12C mutation or pan-KRAS inhibitors, and approaches to indirectly targeting KRAS. In this review, we provide a comprehensive overview of the molecular and mutational characteristics of KRAS and summarize the development and current status of covalent inhibitors targeting the KRAS^G12C mutation. We also discuss emerging promising KRAS-targeted therapeutic strategies, with a focus on mutation-specific and direct pan-KRAS inhibitors and indirect KRAS inhibitors through targeting the RAS activation-associated proteins Src homology-2 domain-containing phosphatase 2 (SHP2) and son of sevenless homolog 1 (SOS1), and shed light on current challenges and opportunities for drug discovery in this field.