Dual Inhibitors of KRASG12D and HSP90 Are Effective against KRASG12D Inhibitor Resistance.

KRAS G12D is a common oncogenic driver mutation in diverse cancers, including non-small cell lung cancer, colorectal cancer, and pancreatic cancer. KRASG12D inhibitors have recently progressed into clinical trials but will likely face innate or acquired drug resistance similar to that which has been observed for KRASG12C inhibitors, such as activation of receptor tyrosine kinases, KRAS independence, and reactivation of RAS-MAPK signaling. This study investigates heterobifunctional small-molecule dual inhibitors that simultaneously target both KRASG12D and protein chaperone HSP90 in KRASG12D-mutated cancer cell lines and patient-derived organoids. Our findings reveal that the efficacy of the clinical-stage KRASG12D inhibitor MRTX1133 varies, with notable resistance being observed in some cell line and organoid models. In contrast, KRASG12D-HSP90 dual inhibitors were found to broadly display superior effectiveness in inducing apoptosis, reducing cell viability, and suppressing key downstream signaling pathways such as AKT and ERK1/2 in MRTX1133-resistant models. The rationale for targeting HSP90, which is preferentially activated in cancer cells, alongside KRASG12D, arises from the ability of HSP90 inhibition to destabilize substrate client proteins that are essential for cancer cell survival and have also been implicated in resistance to KRAS inhibitors. This dual-inhibitor approach presents a promising new strategy to combat de novo and acquired drug resistance in KRASG12D-mutated cancers and potentially paves the way for improved clinical outcomes by addressing the complex molecular mechanisms underlying cancer cell evolution that enables resistance to conventional inhibitors.