Summers, Elizabeth J

Abstract Background Meningiomas lack effective therapies for recurrent or aggressive disease. NF2 inactivation, commonly in meningioma, may sensitize tumors to FAK inhibition and interact with MAPK signaling. This study investigated the therapeutic activity of defactinib (FAK inhibitor) and avutometinib (RAF/MEK inhibitor) alone and in combination in preclinical meningioma models. Methods MAPK-altered meningioma cell lines, IOMM-Lee (NF2 wild-type, BRAF p.V600E) and CH157-MN (NF2 mutant, NRAS p.Q61K), BenMen-1 (NF2 mutant, MAPK wild-type), and three patient-derived NF2 mutant cell lines were cultured in matrigel and treated with defactinib and avutometinib in 3D cell viability assays. In vivo, flank and intracranial xenograft models of IOMM-Lee and CH157-MN were treated with VS-4718 (FAK inhibitor, superior pharmokinetics in mice), avutometinib, or combination. Tumor growth, survival, and pharmacokinetic/pharmacodynamic properties were assessed. Results In vitro, combination therapy showed synergistic or additive effects in CH157-MN and IOMM-Lee cells, respectively. Defactinib alone demonstrated activity in NF2-mutant patient-derived and BenMen-1 cells, while avutometinib did not. In vivo, avutometinib monotherapy suppressed tumor growth and extended survival in both flank and intracranial xenograft models, with evidence of favorable pharmacokinetic properties and target pathway inhibition in intracranial tumors. Combination therapy provided enhanced and sustained control of flank CH157-MN meningioma compared to avutometinib alone but did not significantly improve survival over avutometinib alone in intracranial models. Conclusions Avutometinib demonstrated robust anti-tumor effects in flank and intracranial models of MAPK-altered meningioma. Combination benefits were context dependent. Defactinib activity in NF2-mutant patient-derived cells without targetable MAPK-kinase alterations highlights the importance of genomic biomarkers to guide personalized strategies.

Abstract BACKGROUND High-grade and recurrent meningiomas frequently demonstrate aggressive behavior and therapeutic resistance, with limited treatment options. Dysregulation of the MAPK and FAK pathways drive meningioma progression, but compensatory activation between these pathways could limit single agent efficacy. Recently, a clinical trial (Alliance A071401) showed encouraging efficacy of single-agent FAK inhibition in recurrent/progressive meningioma (Brastianos et al, JCO 2023). This preclinical study aimed to evaluate the therapeutic potential of dual RAF/MEK (avutometinib) and FAK (VS-4718) inhibition in suppressing tumor growth and improving survival in intracranial meningioma models. METHODS Orthotopic intracranial models were established by injecting IOMM-Lee (Fluc-mCherry) or CH157-MN (eGFP-LUC2) cells into nu/nu mice. Mice were randomized into four groups: vehicle, VS-4718 (murine formulation of defactinib, 50 mg/kg, BID), avutometinib (0.3 mg/kg, QD), or combination therapy. Treatments were administered for a 4-week period. Tumor growth was monitored via bioluminescent imaging (BLI) at baseline, midpoint, and study endpoint. Pharmacokinetic (PK) and pharmacodynamic (PD) effects were assessed by intratumoral drug concentrations and Western blotting for p-ERK and p-AKT, respectively. RESULTS In the NF2-mutant CH157-MN model, avutometinib increased median survival from 12.5 to 20.5 days (p=0.001), while combination therapy extended survival further to 22 days (p<0.0001 vs vehicle). Similarly, in the NF2-wildtype IOMM-Lee model, avutometinib raised survival from 27.5 to 33 days (p=0.0237), with combination therapy reaching 34.5 days (p=0.0057 vs vehicle). VS-4718 monotherapy did not extend survival in both models. BLI demonstrated significant inhibition of tumor growth in both avutometinib and combination groups in both tumor models. PK analysis revealed Kp values of 0.26–0.37 for avutometinib and 0.46–0.50 for VS-4718 in orthotopic tumor tissue. Furthermore, combination therapy lowered p-ERK in tumors (p=0.001) compared to vehicle. CONCLUSION Dual RAF/MEK and FAK inhibitor therapy blocks MAPK activation and enhances survival in orthotopic meningioma models, supporting further clinical evaluation for aggressive meningiomas.

Abstract BACKGROUND Patients with meningiomas who have progressed after multimodal treatments face a significant shortage of viable therapeutic options. Recent advancements in the molecular understanding of meningiomas have identified the FAK and RAF/MEK signaling pathways as potential promising targets for progressive meningiomas. METHODS In vitro, we tested two human meningioma cell lines, IOMM-Lee (NF2 wild-type and CDKN2A loss) and CH157-MN (NF2 mutant). The cells were plated in Matrigel-coated wells, treated with defactinib (FAK inhibitor), VS-6766 (RAF/MEK inhibitor, avutometinib) and the combination over a 7-day period and assessed for cell viability using the CellTiter-Glo 3D assay. In vivo, we tested the efficacy of the FAK inhibitor VS-4718 (possessing favorable pharmacokinetic properties in mice) and RAF/MEK inhibitor VS-6766, both given daily via oral gavage, in athymic nude mice bearing IOMM-Lee or CH157-MN tumors. RESULTS In the matrigel assay, VS-6766 suppressed IOMM-Lee and CH157-MN cells in a dose dependent manner. The drug combination was mostly additive in IOMM-Lee cells. However, CH157-MN cells showed a strong synergistic response across all drug concentrations tested. In the IOMM-Lee flank tumor model, VS-4718 alone had no effect, while VS-6766 alone or in combination significantly reduced tumor growth and extended median survival from 25 days to 47 days (p < 0.05). In the CH157 flank tumor model, VS-4718 monotherapy did not affect tumor growth or survival, but VS-6766 monotherapy slowed tumor growth and increased median survival from 10 days to 31 days (p < 0.001). Combining both drugs further reduced tumor growth and extended median survival to 42 days (p < 0.001). CONCLUSION Treatment with FAK and RAF/MEK inhibitors showed synergistic or combination effects in the NF2 mutant CH157-MN model in vitro and in vivo. RAF/MEK inhibitor monotherapy was effective for the IOMM-Lee model (NF2 wild-type), without clear benefit of combining with the FAK inhibitor. Investigations in intracranial tumor models are underway.