pyrimidinones and Nerve-Sheath-Neoplasms

Neurofibromatosis Type 1 (NF1)-related Malignant Peripheral Nerve Sheath Tumors (MPNST) are highly resistant sarcomas that account for significant mortality. The mechanisms of therapy resistance are not well-understood in MPNSTs, particularly with respect to kinase inhibition strategies. In this study, we aimed to quantify the impact of both the genomic context and targeted therapy on MPNST resistance using reverse phase phosphoproteome array (RPPA) analysis. We treated tumorgrafts from three genetically engineered mouse models using MET (capmatinib) and MEK (trametinib) inhibitors and doxorubicin, and assessed phosphosignaling at 4 h, 2 days, and 21 days. Baseline kinase signaling in our mouse models recapitulated an MET-addicted state (NF1-MET), P53 mutation (NF1-P53), and HGF overexpression (NF1). Following perturbation with the drug, we observed broad and redundant kinome adaptations that extended well beyond canonical RAS/ERK or PI3K/AKT/mTOR signaling. MET and MEK inhibition were both associated with an initial inflammatory response mediated by kinases in the JAK/STAT pathway and NFkB. Growth signaling predominated at the 2-day and 21-day time points as a result of broad RTK and intracellular kinase activation. Interestingly, AXL and NFkB were strongly activated at the 2-day and 21-day time points, and tightly correlated, regardless of the treatment type or genomic context. The degree of kinome adaptation observed in innately resistant tumors was significantly less than the surviving fractions of responsive tumors that exhibited a latency period before reinitiating growth. Lastly, doxorubicin resistance was associated with kinome adaptations that strongly favored growth and survival signaling. These observations confirm that MPNSTs are capable of profound signaling plasticity in the face of kinase inhibition or DNA damaging agent administration. It is possible that by targeting AXL or NFkB, therapy resistance can be mitigated.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Doxorubicin; Extracellular Signal-Regulated MAP Kinases; Imidazoles; MAP Kinase Signaling System; Mice; Mice, SCID; Nerve Sheath Neoplasms; Neurofibromin 1; NF-kappa B; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Proteome; Proto-Oncogene Proteins c-akt; Pyridones; Pyrimidinones; ras Proteins; STAT Transcription Factors; Topoisomerase II Inhibitors; TOR Serine-Threonine Kinases; Triazines

Loss of the RAS GTPase-activating protein (RAS-GAP) NF1 drives aberrant activation of RAS/MEK/ERK signaling and other effector pathways in the majority of malignant peripheral nerve sheath tumors (MPNST). These dysregulated pathways represent potential targets for therapeutic intervention. However, studies of novel single agents including MEK inhibitors (MEKi) have demonstrated limited efficacy both preclinically and clinically, with little advancement in overall patient survival. By interrogation of kinome activity through an unbiased screen and targeted evaluation of the signaling response to MEK inhibition, we have identified global activation of upstream receptor tyrosine kinases (RTK) that converges on activation of RAS as a mechanism to limit sensitivity to MEK inhibition. As no direct inhibitors of pan-RAS were available, an inhibitor of the protein tyrosine phosphatase SHP2, a critical mediator of RAS signal transduction downstream of multiple RTK, represented an alternate strategy. The combination of MEKi plus SHP099 was superior to MEKi alone in models of NF1-MPNST, including those with acquired resistance to MEKi. Our findings have immediate translational implications and may inform future clinical trials for patients with MPNST harboring alterations in

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Mice, Nude; Mitogen-Activated Protein Kinase Kinases; Nerve Sheath Neoplasms; Neurofibroma; Neurofibromin 1; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Pyridones; Pyrimidinones; ras Proteins; Small Molecule Libraries; Xenograft Model Antitumor Assays