Spotlight on Sotorasib (AMG 510) for KRAS(G12C) Positive Non-Small Cell Lung Cancer

Mutations in codon 12 of KRAS have been identified in 13% of non-small cell lung cancer patients. Developing targeted therapies against KRAS(G12C) mutation has proven to be challenging due to the abundance of GTP in the cytoplasm, rapid hydrolysis of GTP, and difficulty designing small molecules to achieve sufficient concentration for KRAS inhibition. Based on promising results in both preclinical and clinical trials, sotorasib, a novel KRAS(G12C) inhibitor, was given conditional approval by the FDA in May 2021. The Phase I portion of the clinical trial produced 32% confirmed response with 56% of patients with stable disease. About 91.2% of patients who received the highest dose of 960mg daily achieved disease control. The Phase II portion, which used 960mg daily dosing resulted in 37.1% of patients with confirmed response and 80.6% of patients with disease control. Both phase I and phase II had similar progression-free survival, in 6.3 months and 6.8 months, respectively. In both phases, grade 4 adverse events occurred in only one patient. The most common adverse events were elevations in LFTs, which down-trended upon dose reduction and steroid treatment. While the conditional approval of sotorasib was a major breakthrough for those patients harboring KRAS(G12C) mutations, resistance mutations to sotorasib are increasingly common. Many proposals have been made to address this, such as the use of combination therapy for synthetic lethality, which are producing encouraging results. Here, we explore in further detail the development of sotorasib, its efficacy, mechanism of resistance, and strategies to overcome these resistances.