RMC-4550

We found that both cobimetinib and daytime RMC-4550 similarly reduced tumor volume. Diurnal patterns of monocyte trafficking were disrupted in tumor-bearing mice, and SHP2 inhibition reduced tumor volume only when administered during the day, when myeloid infiltration was low. These findings suggest that SHP2 inhibitor-driven tumor shrinkage requires targeting monocyte-derived macrophages and is influenced by the timing of drug administration.

Consequently, RMC-4550 and venetoclax are synergistically lethal in AML cell lines and in clinically relevant xenograft models. Our results provide mechanistic rationale and pre-clinical evidence for co-targeting SHP2 and BCL2 in RTK-driven AML.

In NF1 mutant glioblastoma in vitro and in vivo models, cellular response to both upstream (SHP2) and downstream (MEK) inhibition are mediated by Ras/Raf/MEK signaling while RMC-4550 alone uniquely regulates a focal adhesion network associated with EMT and demonstrates improved efficacy in vivo.

We found that the SHP2 inhibitors RMC-4550 and SHP099 enhanced growth inhibition of MPN model cell lines (e.g., SET2 and UKE1) in combination with ruxolitinib, effectively preventing ruxolitinib persistent growth. Importantly, the combination of SHP2 inhibition using RMC-4550 with JAK2 inhibition using ruxolitinib for 4 weeks in wildtype mice was well tolerated with respect to hematologic parameters and exemplified by no effect on body weight (Panel B). Given SHP2 inhibitors are already undergoing clinical evaluation in patients with solid tumors, our findings suggest that SHP2 is a therapeutic target with potential to be rapidly translated to clinical assessment for MPN patients.

3 Methods In this study we use a novel, covalent tri-complex KRASG12C(ON) inhibitor, RM-029, which targets KRASG12C in the active state in combination with the SHP2 inhibitor RMC-4550 (both preclinical tool compounds), and studied their in vivo anti-tumor activity on transplantable KRAS-mutant lung cancer mouse models of varying immunogenicities...Results In vitro, RM-029 exhibited higher potency for inhibition of cell viability than the KRASG12C(OFF) inhibitor MRTX849 in both human and murine NSCLC cell lines...This is accompanied by significant TME reorganization, including depletion of immunosuppressive innate immune cells and recruitment and activation of T and NK cells. Conclusions Overall, our preclinical results demonstrate the potential of the combination of KRASG12C(ON) inhibitors with SHP2 inhibitors and/or immune checkpoint blockade not only by targeting KRAS-driven proliferation in tumour cells but by stimulating anti-tumour immunity.

As a result of our findings, combined inhibition of SHP2 and ERK is currently under investigation in a clinical trial (SHERPA, SHP2 and ERK inhibition in pancreatic cancer, NCT04916236), in patients with KRAS-mutant NSCLC, CRC and PDAC.

Treatment with RM-029 still resulted in some degree of adaptive RAS pathway reactivation, which can be blocked using the SHP2 inhibitor RMC-4550...We find evidence of bystander immune mediated killing of G12Ci-resistant cells in response to the different treatment combinations. Overall, our preclinical results demonstrate the potential of the combination of KRASG12C(ON) inhibitors with SHP2 and/or immune checkpoint blockade not only by targeting KRAS-driven proliferation in tumor cells but by stimulating anti-tumor immunity to target both G12Ci sensitive and resistant cells.

The three lines exhibit similar in vitro sensitivities to KRAS inhibitors (MRTX-1257, MRTX-849, AMG-510), but distinct in vivo responses to MRTX-849 ranging from progressive growth with orthotopic LLC-NRAS KO tumors to modest shrinkage with mKRC.1 tumors. All three cell lines exhibited synergistic in vitro growth inhibition with combinations of MRTX-1257 and the SHP2/PTPN11 inhibitor, RMC-4550...Notably, single-agent MRTX-849 activity in mKRC.1 tumors and the combination response in LLC-NRAS KO tumors was lost when the experiments were performed in athymic nu/nu mice, supporting a growing literature demonstrating a role for adaptive immunity in the response to this class of drugs. These new models of murine KRAS mutant lung cancer should prove valuable for identifying improved therapeutic combination strategies with KRAS inhibitors.

Finally, we show evidence that F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to assess early drug responses in animal models. Based on these results, we will investigate this drug combination in the SHP2 and ERK inhibition in pancreatic cancer (SHERPA; ClinicalTrials.gov: NCT04916236) clinical trial, enrolling patients with KRAS-mutant PDAC.

In this study we combine a novel covalent tricomplex KRASG12C(ON) inhibitor, RM-029, which targets the GTP-bound active state, with the SHP2 inhibitor RMC-4550 and analyse if treatment can result in favorable changes in the immune tumor microenvironment (TME) which can lead to adaptive anti-tumor immune responses... In vitro, RM-029 exhibited higher potency for inhibition of cell viability than the KRASG12C(OFF) inhibitor MRTX849 in human NSCLC cell lines... Overall, these preclinical data show that both KRASG12C(ON) and SHP2 inhibitors induce significant remodelling of the TME while their combination blocks RAS pathway reactivation, increasing tumour responses and sensitising immune evasive tumours to anti-PD1 blockade.

These data suggest that SHP2 inhibitors could offer a novel and effective targeted treatment approach for XLP patients.

In this study, we showed that pharmacological inhibition of SHP2 activity using SHP099 and RMC-4550 efficiently inhibited the proliferation of MM cells by inducing apoptosis and cell cycle arrest. In addition, SHP2 inhibitors synergized the antineoplastic effect of bortezomib in bortezomib-sensitive MM cells and showed identical efficacy in targeting bortezomib-resistant MM cells. Overall, our findings suggest that SHP2-specific inhibitors trigger anti-myeloma activity in vitro and in vivo by regulating the ERK pathway and enhancing cytotoxicity of bortezomib, providing therapeutic benefits for both bortezomib naïve and resistant MM.