Project description:One of the most robust synthetic lethal interactions observed in multiple functional genomic screens has been the dependency on PRMT5 in cancer cells with MTAP deletion. Here we report the discovery of the clinical stage MTA-cooperative PRMT5 inhibitor, AMG 193. AMG 193 preferentially binds PRMT5 in the presence of MTA and has potent biochemical and cellular activity in MTAP-deleted cells across multiple cancer lineages. In vitro, PRMT5 inhibition induces DNA damage, cell cycle arrest, and aberrant alternative mRNA splicing in MTAP-deleted cells. In human cell line and patient-derived xenograft models, AMG 193 induces robust anti-tumor activity and is well tolerated with no impact on normal hematopoietic cell lineages. AMG 193 synergizes with chemotherapies or the KRASG12C inhibitor sotorasib in vitro, and combination treatment in vivo significantly inhibits tumor growth. Finally, AMG 193 is demonstrating promising evidence of clinical activity, including confirmed partial responses in patients with MTAP-deleted solid tumors from an ongoing phase 1 / 2 clinical study.
Project description:Previous studies implicated PRMT5 as a synthetic lethal target for MTAP deleted (MTAP del) cancers, however, the pharmacological characterization of small molecule inhibitors that recapitulate the synthetic lethal phenotype have not been described. MRTX1719 selectively inhibited PRMT5 in the presence of MTA, which is elevated in MTAP del cancers, and inhibited PRMT5-dependent activity and cell viability with >70-fold selectivity in HCT116 MTAP del compared to HCT116 MTAP WT cells. MRTX1719 demonstrated dose-dependent anti-tumor activity and inhibition of PRMT5-dependent SDMA modification in MTAP del tumors. In contrast, MRTX1719 demonstrated minimal effects on SDMA and viability in MTAP WT tumor xenografts, mouse or human hematopoietic cells. MRTX1719 demonstrated marked anti-tumor activity across a panel of xenograft models at well-tolerated doses. Early signs of clinical activity were observed including objective responses in patients with MTAP del melanoma, gallbladder adenocarcinoma, mesothelioma, non-small cell lung cancer, and MPNST from the Phase 1/2 study. Significance: PRMT5 was identified as a synthetic lethal target for MTAP del cancers, however, previous PRMT5 inhibitors do not selectively target this genotype. The differentiated binding mode of MRTX1719 leverages the elevated MTA in MTAP del cancers and represents a promising therapy for the ~10% of cancer patients with this biomarker.
Project description:Type I Protein Arginine Methyltransferases (PRMTs) catalyze asymmetric dimethylation of arginine (ADMA) residues on numerous protein substrates to modulate their activity. Type I PRMTs and many of their substrates have been implicated in human cancers, suggesting that inhibiting Type I PRMT activity offers a tractable approach for therapeutic intervention. The current report describes GSK3368715 (EPZ019997), a potent, reversible Type I PRMT inhibitor with anti-tumor activity against human cancer cells both in vitro and in vivo. GSK3368715 reduces ADMA on numerous substrates and concomitantly increases monomethyl (MMA) and symmetric dimethyl arginine (SDMA) levels. Inhibition of PRMT5, the major type II PRMT, attenuates this induction and produces synergistic antiproliferative effects in combination with GSK3368715 in cancer cells. PRMT5 activity is inhibited by 2-methylthioadenosine (MTA), a naturally occurring metabolite that accumulates in tumor cells deficient for the enzyme Methylthioadenosine Phosphorylase (MTAP). MTAP deletion in cancer cell lines correlates with sensitivity to GSK3368715, indicating a sufficient degree of PRMT5 inhibition from MTA accumulation to achieve a tumor cell-intrinsic combination. These data provide the rationale to explore MTAP status as a biomarker strategy for patient selection to maximize the anti-tumor activity of GSK3368715.
Project description:Abstract The aggressive nature and poor prognosis of lung cancer led us to explore the mechanisms driving disease progression. Utilizing our invasive cell-based model, we identified methylthioadenosine phosphorylase (MTAP) and confirmed its suppressive effects on tumorigenesis and metastasis, and patients with low MTAP expression displayed worse overall and progression-free survival. Mechanistically, accumulation of methylthioadenosine substrate in MTAP-deficient cells reduced the level of protein arginine methyltransferase 5 (PRMT5)-mediated symmetric dimethylarginine (sDMA) modification on proteins. Vimentin was revealed as a novel dimethyl-protein with less dimethylation level in response to MTAP loss. The sDMA modification on vimentin reduces its protein abundance and trivially affects its filamentous structure. In MTAP-loss cells, lower sDMA level prevents ubiquitination-mediated vimentin degradation, thereby stabilizing vimentin, contributing to cell invasion. This inverse association of the MTAP/PRMT5 axis with vimentin proteins was clinically corroborated. Taken together, we propose a novel mechanism of vimentin post-translational regulation and provide new insights in metastasis.
Project description:PRMT5 is an essential arginine methyltransferase and a therapeutic target in MTAP null cancers. PRMT5 utilizes adaptor proteins for substrate recruitment through a previously undefined mechanism. Here, we identify an evolutionarily conserved peptide sequence shared among the three known substrate adaptors (CLNS1A, RIOK1 and COPR5) and show it is necessary and sufficient for interaction with PRMT5. We demonstrate that PRMT5 uses modular adaptor proteins containing a common binding motif for substrate recruitment, comparable to other enzyme classes such as kinases and E3 ligases. We structurally resolve the interface with PRMT5 and show via genetic perturbation that it is required for methylation of adaptor-recruited substrates including the spliceosome, histones, and ribosome assembly complexes. Further, disruption of this site affects Sm spliceosome stability and activity, leading to intron retention. Genetic disruption of the PRMT5-substrate adaptor interface leads to a hypomorphic decrease in growth of MTAP null tumor cells in vitro and in vivo, and is thus a novel site for development of therapeutic inhibitors of PRMT5.
Project description:Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have created isogenic MTAP+ and MTAP- HT1080 fibrosarcoma cells. In this experiment we have performed expression array analysis on MTAP-, MTAP+, and MTAP+ cells treated with the MTAP inhibitor MT-DADMe-ImmA. Three biological replicates of each sample were grown and analyzed. M- is MTAP-. M+ is MTAP+, and M+I is MTAP treated with inhibitor (48 hours).
Project description:Methylthioadenosine Phosphorylase (MTAP) is a tumor suppressor gene that encodes an enzyme responsible for the catabolism of the polyamine byproduct 5′deoxy-5′-methylthioadenosine (MTA). To elucidate the mechanism by which MTAP inhibits tumor formation, we have created isogenic MTAP+ and MTAP- HT1080 fibrosarcoma cells. In this experiment we have performed expression array analysis on MTAP-, MTAP+, and MTAP+ cells treated with the MTAP inhibitor MT-DADMe-ImmA.
Project description:Evaluation of anti-myeloma effects of inhibition of PRMT5, involved in arginine methylation. Three human multiple myeloma cell lines were treated with the PRMT5 inhibitor EPZ015938. Transcriptional profiles were compared to untreated controls.