What is the mechanism of Sotorasib?

Sotorasib is a groundbreaking therapeutic agent heralded for its targeted mechanism in treating specific types of cancer, particularly non-small cell lung cancer (NSCLC) with the KRAS G12C mutation. Understanding the mechanism of Sotorasib requires a dive into the molecular interactions and pathways it engages within the cellular environment.

KRAS is a member of the RAS family of genes, which are critical for the regulation of cell division, differentiation, and apoptosis. Mutations in KRAS are amongst the most common oncogenic drivers in human cancers, with the KRAS G12C mutation being particularly prevalent in NSCLC. This mutation leads to the production of a mutant KRAS protein that is locked in an active, GTP-bound state, driving uncontrolled cellular proliferation and tumor growth.

Sotorasib, a small molecule inhibitor, specifically targets the KRAS G12C mutant protein. Its mechanism of action is predicated on covalently binding to the cysteine residue at position 12 of the KRAS protein when it is in its GDP-bound (inactive) state. This selective binding is facilitated by the unique configuration of the G12C mutation, which harbors a cysteine residue that is absent in the wild-type KRAS protein and other KRAS mutations. By irreversibly attaching to this cysteine, Sotorasib locks KRAS in its inactive form.

The covalent binding of Sotorasib to KRAS G12C inhibits the protein’s ability to switch to the active GTP-bound state. Consequently, this inhibition leads to the disruption of downstream signaling pathways that are essential for cell proliferation and survival, particularly the MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase) pathways. These pathways are crucial for transmitting growth signals from the cell surface to the nucleus, thereby regulating gene expression and cell cycle progression.

By halting the aberrant signaling driven by mutant KRAS, Sotorasib effectively impedes tumor growth and promotes cancer cell apoptosis. This targeted approach not only maximizes the therapeutic impact against cancer cells harboring the KRAS G12C mutation but also spares normal cells, thereby minimizing off-target effects and enhancing the overall safety profile of the treatment.

Clinical trials have demonstrated the efficacy of Sotorasib in shrinking tumors and improving survival rates in patients with KRAS G12C-mutated NSCLC. These promising results have paved the way for its approval by regulatory agencies and have underscored the significance of developing targeted therapies based on specific genetic mutations in cancer.

In summary, Sotorasib represents a landmark advancement in precision oncology, offering a highly specific mechanism of action against cancers driven by the KRAS G12C mutation. By covalently binding to and inactivating the mutant KRAS protein, Sotorasib disrupts key signaling pathways essential for cancer cell survival and proliferation, thereby providing a potent and targeted therapeutic option for patients with limited treatment alternatives.