Potent mTOR Inhibitor Research Articles

A Phase 1 Study of ABI-009 (Nab-sirolimus) in Combination With Temozolomide and Irinotecan in Pediatric Patients With Recurrent or Refractory Solid Tumors, Including CNS Tumors-A Children's Oncology Group Pediatric Early Phase Clinical Trial Network Study ADVL1514.

Nab-sirolimus (ABI-009, nab-rapamycin; Aadi Bioscience Inc. [Aadi]) is a human albumin-bound form of sirolimus nanoparticles, a potent mTOR inhibitor. This phase I trial was conducted to define dose-limiting toxicities (DLT), maximum tolerated or recommended phase II dose (MTD/RP2D), and pharmacokinetics of Nab-sirolimus in combination with temozolomide and irinotecan. Using a rolling 6 design, Nab-sirolimus was administered intravenously (IV) on days (D) 1 and 8 of cycle (C) 1. In subsequent cycles, Nab-sirolimus was administered D1 and D8 in combination with temozolomide (125 mg/m2/dose, maximum 250 mg/dose) and irinotecan (90 mg/m2/dose) orally, daily on D1-5. Cycle duration was 21 days. Three dose levels (DL) of Nab-sirolimus were investigated (DL1: 35 mg/m2/dose, DL-1: 20 mg/m2/dose, and DL-2: 15 mg/m2/dose). The observation period for estimating the MTD/RP2D was defined by cycles 1 and 2. Thirty-three patients were enrolled, 32 were eligible. Dose determination included 17 evaluable patients, median (range) age 12 (2-20) years and six additional patients were enrolled (four evaluable for toxicity) on a pharmacokinetic cohort. C1 or C2 DLTs were primarily thrombocytopenia including 2/5 patients at DL1, 2/6 patients at DL-1, and 1/6 patients at DL-2. One patient (DL1) with Ewing Sarcoma had a partial response and remained on study for 35 cycles. Rapamycin clearance was dose dependent. Irinotecan clearance and its active metabolite SN-38 exposure were not affected by coadministration with Nab-sirolimus. The MTD for Nab-sirolimus was 15 mg/m2/dose IV on D1 and D8 in combination with temozolomide 125 mg/m2/dose and oral irinotecan 90 mg/m2/dose daily for 5 days during 21D cycles. ClinicalTrials.gov identifier NCT02975882.

Temsirolimus inhibits FSP1 enzyme activity to induce ferroptosis and restrain liver cancer progression.

Ferroptosis is a non-apoptotic mode of cell death characterized by iron-dependent accumulation of lipid peroxidation. While lipid radical elimination reaction catalyzed by glutathione peroxidase 4 (GPX4) is a major anti-ferroptosis mechanism, inhibiting this pathway pharmaceutically shows promise as an anti-tumor strategy. However, certain tumor cells exhibit redundancy in lipid radical elimination pathways, rendering them unresponsive to GPX4 inhibitors. In this study, we conducted screens across different cancer cell lines and FDA-approved drugs, leading to the identification of temsirolimus in combination with the GPX4 inhibitor RSL3 as a potent inducer of ferroptosis in liver cancer cells. Mechanistically, temsirolimus sensitized liver cancer cells to ferroptosis by directly binding to and inhibiting ferroptosis suppressor protein 1 (FSP1) enzyme. Notably, while temsirolimus is recognized as a potent mTOR inhibitor, its ferroptosis-inducing effect is primarily attributed to its inhibition of FSP1 rather than mTOR activity. By performing in vitro colony formation assays and in vivo tumor xenograft models, we demonstrated that the combination of temsirolimus and RSL3 effectively suppressed liver tumor progression. This tumoricidal effect was associated with increased lipid peroxidation and induction of ferroptosis. In conclusion, our findings underscore the potential of combining multi-target ferroptosis-inducing agents to circumvent resistance to ferroptosis in liver cancer cells and highlight temsirolimus as a promising FSP1 inhibitor and ferroptosis inducer, which also deserves further investigation in translational medicine.

Abstract PO2-20-02: A Phase 3 study of gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor plus a non-steroidal aromatase inhibitor (VIKTORIA-1)

Abstract Patients who receive frontline CDK4/6 inhibitor (CDK4/6i) therapy eventually experience disease progression. Resistance to CDK4/6i is likely a transient adaptive mechanism that may be reversed by inhibition of the PI3K/mTOR pathway. Thus, combination of CDK4/6i and PI3K/mTORi after disease progression on CDK4/6i could restore sensitivity to CDK4/6i and prevent activation of the PI3K/mTOR pathway. This hypothesis was evaluated in a Phase 1b study (Layman SABCS 2021) of gedatolisib (geda), a potent inhibitor of PI3K and mTOR. Subjects with HR+/HER2- ABC treated with prior CDK4/6i received geda (180 mg IV weekly for 3 weeks, then one week off) with palbociclib (P) and fulvestrant (F). Median PFS was 12.9 months with 63% overall response rate. Efficacy was observed regardless of PIK3CA mutation status (Wesolowski SABCS 2022). Geda was well tolerated, with few discontinuations due to treatment-related adverse events (4%). The most common AE was stomatitis; hyperglycemia of any grade occurred in 26% of patients. This preliminary data, dosing schedule, and study population characteristics form the basis for the Phase 3 trial, VIKTORIA-1. This Phase 3 multinational clinical trial will evaluate geda and F with or without P in patients with HR+/HER2- ABC previously treated with any CDK4/6i in combination with a non-steroidal aromatase inhibitor (AI) therapy. Those without tumor PIK3CA mutations will be assigned to Study 1 (n=351) and randomized to Arm A (geda, P, and F), Arm B (geda and F), or Arm C (F). Those with PIK3CA mutations will be assigned to Study 2 (n=350) and randomized to Arm D (geda, P, and F), Arm E (alpelisib and F), or Arm F (geda and F). Key eligibility criteria include adults with confirmed metastatic or locally advanced breast cancer, any menopausal status, radiologically evaluable disease, and prior CDK4/6i treatment in combination with a non-steroidal AI. Prior hormonal therapy, including SERDs, is allowed. Key exclusion criteria include prior treatment with a PI3K, Akt, or mTOR inhibitor, prior treatment with chemotherapy for advanced disease, more than two lines of prior endocrine therapy, bone only disease with no soft tissue components, active CNS metastases, and type 1 diabetes or uncontrolled type 2 diabetes. The primary endpoint is PFS assessed by blinded independent central review per RECIST v1.1. Secondary endpoints included overall survival (OS), safety and tolerability, ORR, duration of response, time to response, CBR, quality of life, and pharmacokinetics. Enrollment is ongoing. This trial abstract was previously presented at the 2022 San Antonio Breast Cancer Symposium, December 6-10, 2022. Citation Format: Sara Hurvitz, Fabrice André, Massimo Cristofanilli, Giuseppe Curigliano, Antonio Giordano, Hyo Han, Miguel Martín, Barbara Pistilli, Hope Rugo, Robert Wesolowski, Igor Gorbatchevsky, Sibylle Loibl. A Phase 3 study of gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor plus a non-steroidal aromatase inhibitor (VIKTORIA-1) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-20-02.

Design, Synthesis, Formulation, and Bioevaluation of Trisubstituted Triazines as Highly Selective mTOR Inhibitors for the Treatment of Human Breast Cancer.

The aberrant activation of the PI3K/mTOR signaling pathway is implicated in various human cancers. Thus, the development of inhibitors targeting mTOR has attracted considerable attention. In this study, we used a structure-based drug design strategy to discover a highly potent and kinase-selective mTOR inhibitor 24 (PT-88), which demonstrated an mTOR inhibitory IC50 value of 1.2 nM without obvious inhibition against another 195 kinases from the kinase profiling screening. PT-88 displayed selective inhibition against MCF-7 cells (IC50: 0.74 μM) with high biosafety against normal cells, in which autophagy induced by mTOR inhibition was implicated. After successful encapsulation in a lipodisc formulation, PT-88 demonstrated favorable pharmacokinetic and biosafety profiles and exerted a large antitumor effect in an MCF-7 subcutaneous bearing nude mice model. Our study shows the discovery of a highly selective mTOR inhibitor using a structure-based drug discovery strategy and provides a promising antitumor candidate for future study and development.

Abstract 599: Combination of CDK4/6 inhibitors with biguanides for treatment of triple negative breast cancer

Abstract Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer (BC) and is associated with early relapse and high frequency of metastasis. This has been attributed in part to the lack of targeted therapies. TNBC occurs more frequently in younger women of African and Hispanic ancestry and with a higher risk of mortality than women of European ancestry. Emerging data shows activation of the AKT/mTOR pathway by insulin may occur in aggressive TNBC and inhibition of mTOR signaling by rapamycin, a potent mTOR inhibitor, induces cell cycle arrest and downregulation of cyclin D1 in TNBC cells. CDK4/6 inhibitors have demonstrated to be an effective therapeutic for estrogen receptor positive BC and although their use in TNBC patients remains uncertain their use in combination with other targeted therapies may be promising. We have developed a set of newly designed biguanides with potent anticancer action and safety doses in vivo that in combination with CDK4/6 inhibitors block TNBC cell growth in vitro and in vivo. Using TNBC cell proliferation in vitro assays, new biguanides show dose-dependent inhibition of cell proliferation (P<0.01). Further, combination of biguanides with ribocliclib, an orally bioavailable CDK4/6 inhibitor, produced additive and synergistic effects in TNBC cell lines in vitro (P<0.01). Biguanides are known to activate de LKB1-AMPK pathway. Western immunoblots showed our biguanide analogues also induce AMPK phosphorylation and significantly reduce phosphorylation of downstream mTOR signaling pathway components including S6 ribosomal protein and 4E-BP1, an effect that is potentiated by combination treatment with ribociblib. Further, cyclin D1 is known to be overexpressed in about 50% of BCs and binding to CDK 4/6 induces phosphorylation of Rb and cell cycle progression. Treatment with biguanides downregulated cyclin D1 expression in TNBC cells and combination treatment of ribociclib with biguanide JD006 was more effective at decreasing Rb phosphorylation than each drug alone. In addition, seahorse analysis evaluated mitochondrial respiratory function. Treatment with biguanides inhibited oxidative phosphorylation in a dose dependent manner, an important metabolic pathway that can drive drug resistance to therapy in cancer cells. In vivo, combination treatment of ribociclib with biguanide JD006 was more effective than each agent alone in stopping human TNBC xenograft progression in nude mouse models (P<0.05). Our preliminary data offer evidence that human TNBC are highly vulnerable to metabolic reprogramming by new biguanides. This work can yield insight on unanticipated mechanisms of biguanide action and rationale for new combination therapies with CDK 4/6 inhibitors as a new option for treatment of TNBC. Funding: CBCRP B27IB3869, JCCC Breast Cancer Award, Hickey Family Foundation, NCI U54 CA143930, Team Research Grant, UCLA TDG. Citation Format: Mario Morales Martinez, Eduardo Mauricio Gonzalez, Gang Deng, Gaoyuan Ma, Hyunsoo Kim, Linsey Stiles, Nalo Hamilton, Michael E. Jung, Richard J. Pietras, Diana C. Marquez-Garban. Combination of CDK4/6 inhibitors with biguanides for treatment of triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 599.

Designing of target‐specific N‐substituted tetrahydroquinoline derivatives as potent mTOR inhibitors via integrated structure‐guided computational approaches

AbstractThere is a need to develop innovative, safe, and more effective treatment methods for lung cancer due to obstacles including resistance, side effects, and low bioavailability, among others related to present medicines. Our previous research findings gave some promising results of tetrahydroquinoline (THQ) derivatives as mTOR inhibitors for the treatment of lung cancer. The current research has employed certain integrated computational techniques to enhance the effectiveness of THQ derivatives. Various computational methods, like the generation of the pharmacophore model, virtual screening, and QSAR modeling were employed to achieve the goal, and their results were connected to develop novel THQ analogues. This study revealed that among 48 newly designed THQ derivatives, the compound UC_1 indicated the XP Gscore of −9.378 kcal/mol and also showed the key amino acid interactions with the mTOR protein viz. Gln2167, Val2240. Interestingly, compound UC_1 showed a better binding affinity with the mTOR protein compared to the clinical trial molecules viz. AZD‐8055 and AZD‐2014. The molecular dynamics simulations (100 ns) along with each output give a shred of strong evidence that the designed THQ derivative (UC_1) has all the required features in terms of inhibiting mTOR protein for the treatment of lung cancer.

Neuron-derived extracellular vesicles to examine brain mTOR target engagement with sirolimus in patients with multiple system atrophy

IntroductionImpaired autophagy is a pathogenic mechanism in the synucleinopathies. Sirolimus, a potent mTOR inhibitor and autophagy activator, had no beneficial effects in a randomized placebo-controlled trial in patients with multiple system atrophy (MSA). Whether sirolimus effectively inhibited brain mTOR activity was unknown. We aimed to evaluate if patients with MSA treated with sirolimus had evidence of inhibited brain mTOR pathways by measuring neuron-derived serum extracellular vesicles (NEVs). MethodsSerum samples were collected from participants of the sirolimus-MSA trial, which randomized patients to sirolimus (2–6 mg/day) or placebo for 48 weeks. NEVs were immunoprecipitated with three antibodies-against neurons. Brain mTOR engagement was quantified as the change in the NEV phosphorylated mTOR (p-mTOR) to total-mTOR (tot-mTOR) ratio after 48 weeks of sirolimus. ResultsSamples from 27 patients [mean (±SD) age, 59.2±7 years, 15 (55.5%) men] were analyzed (19 sirolimus, 8 placebo). Treated- and placebo-patients had similar p-mTOR:tot-mTOR ratio at 24 (placebo: 0.248 ± 0.03, sirolimus: 0.289 ± 0.02; P = 0.305) and 48 weeks (placebo: 0.299 ± 0.05, sirolimus: 0.261 ± 0.03; P = 0.544). The tot-mTOR, p-mTOR, or their ratio levels were not associated with Unified MSA Rating Scale (UMSARS) worsening. DiscussionThese results are consistent with no brain mTOR engagement by oral sirolimus up to 6 mg/day. NEV-based biomarkers are a rational approach to investigating target engagement in clinical trials of brain-targeted therapeutics.

Molecular mechanisms underlying equine endometrial cup regression: a transcriptomic analysis

The gonadotropin-secreting equine endometrial cups (EC) have a major role in pregnancy maintenance, but an intriguingly short lifespan. First seen in the maternal endometrium at days (d) 38-40 post-ovulation, the EC undergo degeneration via poorly understood mechanisms starting around d 60-70, with complete dehiscence at approximately 120-150 d of gestation. Pregnancy losses during the EC physiological lifespan and EC pathological persistence after abortion or uncomplicated parturition usually lead to irregular estrous cyclicity and subfertility, with only anecdotal and inconsistent therapeutic options currently available. A holistic understanding of the cellular signaling leading to EC regression may provide insight for development of effective therapies for retained or persistent EC. We therefore hypothesized that comparing the transcriptome of EC during development and regression could elucidate key regulators and molecular pathways leading to EC trophoblast cell demise. Samples of EC were dissected from the adjacent endometrium of pregnant pony mares during early development (DEC, 42-47 d post-ovulation, n = 5), and regression (REC, 96 – 120 d, n = 5). Next generation RNA sequencing was performed with Illumina NovaSeq6000 and reads mapped to EquCab3.0 (STAR-2.5.2b). Differentially expressed genes (DEGs) were identified with Cuffdiff-2.2.1 (FDR < 0.05). A total of 2,504 DEG were identified, being 1,648 upregulated and 856 downregulated in REC when compared to DEC. Pathway Analysis of DEGs was also performed (IPA, Qiagen). Interestingly, the main pathways affected in REC included oxidative phosphorylation (P = 1.08e-38);mitochondrial dysfunction (P = 2e-25); estrogen receptor signaling (P = 2.2e-10); Sirtuin signaling pathway (P = 9.64e-16), which has central regulatory roles in cell senescence and apoptosis; and Granzyme A Signaling (3.29e-15), associated with Cytotoxic T Lymphocyte and Natural Killer-mediated apoptosis via caspase-independent pathways. Upstream regulator analysis highlighted the roles of mitochondrial protein ubiquinol-cytochrome c reductase complex-3; rapamycin-insensitive companion of mTOR, an essential molecule in cellular homeostasis; Torin-1, a potent mTOR inhibitor; dead box protein 5, which may act as a co-activator of estrogen receptor signaling; and transducing-like enhancer protein-3, a member of a family of proteins that regulate cell fate through the Notch signaling pathway. Importantly, the main upstream regulators and downstream molecules are also involved in cancer cell biology (P = 1.32e-07 – 1.71e-122), including the downstream effectors of neoplastic and epithelial cell death secreted phosphoprotein 1 (Spp1), and secreted protein acidic and cysteine rich (Sparc). Along with aromatase, Spp1 and Sparc were upregulated in REC in comparison to DEC. In summary, we have highlighted key molecular pathways and regulators of EC regression, which merit further molecular and functional investigations. Since multiple identified molecules have also been targeted in human oncological treatments, further investigation of their effectiveness in hastening EC demise is warranted.

A phase 3 study of gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/ HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor plus a nonsteroidal aromatase inhibitor (VIKTORIA-1).

TPS1118 Background: Patients who receive frontline CDK4/6 inhibitor (CDK4/6i) therapy eventually experience disease progression. Resistance to CDK4/6i is likely a transient adaptive mechanism that may be reversed by inhibition of the PI3K/mTOR pathway. Thus, combination of CDK4/6i and PI3K/mTORi after disease progression on CDK4/6i could restore sensitivity to CDK4/6i and prevent activation of the PI3K/mTOR pathway. This hypothesis was evaluated in a Phase 1b study (Layman SABCS 2021) of gedatolisib (geda), a potent inhibitor of PI3K and mTOR. Subjects with HR+/HER2- ABC with prior CDK4/6i received geda (180 mg IV weekly for 3 weeks, then one week off) with palbociclib (palbo) and fulvestrant (FUL). Median PFS was 12.9 months with 63% overall response rate. Efficacy was observed regardless of PIK3CA mutation status (Wesolowski SABCS 2022). Geda was well tolerated, with few discontinuations due to treatment-related adverse events (4%). The most common AE was stomatitis; hyperglycemia of any grade occurred in 26% of patients. This preliminary data, dosing schedule, and study population characteristics form the basis for the Phase 3 trial, VIKTORIA-1 (NCT05501886). Methods: This Phase 3 multinational clinical trial will evaluate geda and FULwith or without palboin patients with HR+/HER2- ABC previously treated with any CDK4/6i in combination with a non-steroidal aromatase inhibitor (AI) therapy. Those without tumor PIK3CA mutations will be assigned to Study 1 (n=351) and randomized to Arm A (geda, palbo, and FUL), Arm B (geda and FUL), or Arm C (FUL). Those with PIK3CA mutations will be assigned to Study 2 (n=350) and randomized to Arm D (geda, palbo, and FUL), Arm E (alpelisib and FUL), or Arm F (geda and FUL). Key eligibility criteria include adults with confirmed metastatic or locally advanced breast cancer, any menopausal status, radiologically evaluable disease, and prior CDK4/6i treatment in combination with a non-steroidal AI. Prior hormonal therapy, including SERDs, is allowed. Key exclusion criteria include prior treatment with a PI3K, Akt, or mTOR inhibitor, prior treatment with chemotherapy for advanced disease, more than two lines of prior endocrine therapy, bone only disease with no soft tissue components, active CNS metastases, and type 1 diabetes or uncontrolled type 2 diabetes. The primary endpoint is PFS assessed by blinded independent central review per RECIST v1.1. Secondary endpoints included overall survival, safety and tolerability, ORR, duration of response, time to response, CBR, quality of life, and pharmacokinetics. The trial is open for enrollment. Clinical trial information: NCT05501886 .

FIR-preconditioning promotes Akt-mTOR-exosome manufacture in cooperation with MITF to boost resilience of rat bone marrow-derived stem cells

A previous study from our laboratory observed the protective effects of far-infrared irradiation (FIR) on bone marrow-derived stem cells (BMSCs) against oxidative stress. However, it remains unknown precisely how FIR influences BMSC survival. We identify an unexpected route among the expression of MITF, BCL2, mTOR, and exosome in FIR-preconditioned BMSCs. MITF siRNA demonstrated that loss of MITF expression not only inhibited cell proliferation but also reduced the FIR-mediated expression of mTOR, BCL2, and exosome. mTOR signaling pathways have been implicated in cell growth, proliferation, and survival. We also found that rapamycin, a potent and selective inhibitor of mTOR, when combined with MITF siRNA, repressed FIR-mediated CD63 and BCL2 expression. In addition, FIR-preconditioned BMSCs demonstrated more tolerance in multiple stressful environments than untreated BMSCs. The elevated exosomes in conditioned medium derived from FIR-preconditioned BMSCs also repaired H9c2 cells that sustained cellular damage after subjected to an array of environmental stress conditions. Taken together, these results reveal a possible mechanism about how FIR-preconditioned BMSCs and its conditioned media could contribute to cellular resilience during environmental changes via MITF-Akt-mTOR associated with exosome manufacture. FIR preconditioning could thus complement and improve therapeutic applications of BMSCs on outcomes of various disorders.

Design, synthesis and biological evaluation of novel 9-methyl-9H-purine and thieno[3, 2-d]pyrimidine derivatives as potent mTOR inhibitors

The mammalian target of rapamycin (mTOR) has been proved to be an effective target for cancer therapy. Two kinds of mTOR inhibitors, the rapalogs and mTOR kinase inhibitors (TORKi), have been developed and clinically validated in several types of malignancies. Compared with rapalogs, TORKi can exert better antitumor activity by inhibiting both mTORC1 and mTORC2, but the clinical development of current TORKi candidates has been relative slow, more TORKi with novel scaffold need to be developed to expand the current pipelines. In this study, a series of 9-methyl-9H-purine and thieno[3, 2-d]pyrimidine derivatives were designed, synthesized and biological evaluation. Most of these compounds exhibited good mTOR kinase inhibitory activity and selectivity over PI3Kα. Subsequent antiproliferative assay allowed us to identify the lead compound 15i, which display nanomolar to low micromolar IC50s against six human cancer cell lines. 15i could induce cell cycle arrest of MCF-7, PC-3 and A549 cells at the G0/G1 phase and suppress the migration and invasion of these cancer cells by suppressing the phosphorylation of AKT and P70S6 kinase. It could also regulate autophagy-related proteins to induce autophagy. Therefore, 15i would be a starting point for the development of new TORKi as anticancer drug.

Screening the possible anti-cancer constituents of Hibiscus rosa-sinensis flower to address mammalian target of rapamycin: an in silico molecular docking, HYDE scoring, dynamic studies, and pharmacokinetic prediction.

One of the most common malignancies diagnosed and the leading cause of death for cancer-stricken women globally is breast cancer. The molecular subtype affects therapy options because it is a complex disorder with multiple subtypes. By concentrating on receptor activation, mTOR (mammalian target of rapamycin) can be employed as a therapeutic target. The goal of this work was to screen a number of inhibitors produced from Hibiscus rosa-sinensis for possible target to inhibit the mTOR and to determine which has the greatest affinity for the receptor. Primarily, the ionization states of the chosen compounds were predicted using the ChemAxon web platform, and their pKa values were estimated. Given the significance of interactions between proteins in the development of drugs, structure-based virtual screening was done using AutoDock Vina. Approximately 120 Hibiscus components and ten approved anti-cancer drugs, including the mTOR inhibitor everolimus, were used in the comparative analysis. By using Lipinski's rule of five to the chosen compounds, the ADMET profile and drug-likeness characteristics were further examined to assess the anti-breast cancer activity. The compounds with the highest ranked binding poses were loaded using the SeeSAR tool and the HYDE scoring to give interactive, desolvation, and visual ΔG estimation for ligand binding affinity assessment. Following, the prospective candidates underwent three replicas of 100ns long molecular dynamics simulations, preceded with MM-GBSA binding free energy calculation. The stability of the protein-ligand complex was determined using root mean square deviation (RMSD), root mean square fluctuation (RMSF), and protein-ligand interactions. The results demonstrated that the best mTOR binding affinities were found for stigmastadienol (107), lupeol (66), and taraxasterol acetate (111), which all performed well in comparison to the control compounds. Thus, bioactive compounds isolated from Hibiscus rosa-sinensis could serve as lead molecules for the creation of potent and effective mTOR inhibitors for the breast cancer therapy.

Design, synthesis and pharmacological evaluation of 2-arylurea-1,3,5-triazine derivative (XIN-9): A novel potent dual PI3K/mTOR inhibitor for cancer therapy

Blocking the PI3K/AKT/mTOR pathway has been widely recognized as an attractive cancer therapeutic strategy because of its crucial role in cell growth and survival. In this study, a novel series of 2-arylurea-1,3,5-triazine derivatives had been synthesized and evaluated as highly potent PI3K and mTOR inhibitors. The new compounds exhibited cytotoxic activities against MCF-7, Hela and A549 cancer cell lines (IC50 = 0.03–36.54 μM). The most promising compound XIN-9 exhibited potent inhibition against PI3K and mTOR kinase (IC50 = 23.8 and 10.9 nM). Mechanistic study using real-time PCR revealed the ability of XIN-9 to inhibit PI3K and mTOR. In addition, compound XIN-9 arrested the cell cycle of MCF-7 cells at the G0/G1 phase. XIN-9 also caused a significant dose-dependent increase of early and late apoptotic events. Molecular docking analysis revealed a high binding affinity for XIN-9 toward PI3K and mTOR. Following in vitro studies, XIN-9 was further evaluated in MCF-7 xenograft models to show significant in vivo anticancer efficacies with tumor growth inhibitions of 41.67% (po, 75 mg/kg). Overall, this work indicated that compound XIN-9 represents a potential anticancer targeting PI3K/AKT/mTOR pathway.

Discovery of potential mTOR inhibitors from Cichorium intybus to find new candidate drugs targeting the pathological protein related to the breast cancer: an integrated computational approach.

Breast cancer is the most common malignancy among women. It is a complex condition with many subtypes based on the hormone receptor. The mammalian target of the rapamycin (mTOR) pathway regulates cell survival, metabolism, growth, and protein synthesis in response to upstream signals in both normal physiological and pathological situations, primarily in cancer. The objective of this study was to screen for a potential target to inhibit the mTOR using a variety of inhibitors derived from Cichorium intybus and to identify the one with the highest binding affinity for the receptor protein. Initially, AutoDock Vina was used to perform structure-based virtual screening, as protein-like interactions are critical in drug development. For the comparative analysis, 110 components of Cichorium intybus were employed and ten FDA-approved anticancer medicines, including everolimus, an mTOR inhibitor. Further, the drug-likeness and ADMET properties were investigated to evaluate the anti-breast cancer activity by applying Lipinski's rule of five to the selected molecules. The promising candidates were then subjected to three replica molecular dynamics simulations run for 100ns, followed by binding free energy estimation using MM-GBSA. The data were analyzed using root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), and protein-ligand interactions to determine the stability of the protein-ligand complex. Based on the results, taraxerone (98) revealed optimum binding affinities with mTOR, followed by stigmasterol (110) and rutin (104), which compared favorably to the control compounds. Subsequently, bioactive compounds derived from Cichorium intybus may serve as lead molecules for developing potent and effective mTOR inhibitors to treat breast cancer.

ADVL1514, a phase 1 study of ABI-009 (nab-sirolimus) in pediatric patients with recurrent or refractory solid tumors, including CNS tumors as a single agent and in combination with temozolomide and irinotecan: A Children’s Oncology Group pediatric early-phase clinical trial network study.

10022 Background: nab-Sirolimus (formerly know ABI-009 and nab-rapamycin) is a novel human albumin-bound preparation of sirolimus, a potent mTOR inhibitor. We report results of a Phase I study of ABI-009 alone and in combination with irinotecan and temozolomide in children with relapsed/refractory solid or CNS tumors. Methods: Patients (age 1-21 years) with relapsed/refractory solid or CNS tumors were eligible. Using a rolling 6 design, ABI-009 was administered intravenously as a single agent on Days 1 and 8 of cycle 1 (cycle = 21d), then subsequent cycles ABI-009 was administered in combination with temozolomide (125 mg/m2/dose, maximum 250 mg/dose) orally once daily x 5 on Days 1-5 and irinotecan 90 mg/m2/dose orally once daily x 5 on Days 1-5. Three dose levels (DL) of ABI-009 were investigated (DL1: 35mg/m2/dose, DL-1: 20mg/m2/dose, and DL-2: 15mg/m2/dose). The maximum tolerated dose (MTD) or Recommended Phase 2 Dose (RP2D) was established based on dose limiting toxicity (DLT) observed during Cycle 1 and 2. At the RP2D, additional patients were enrolled for pharmacokinetics (PK). Results: 33 patients were enrolled (32 eligible and 1 ineligible); 11 did not experience DLT but were not evaluable for toxicity due to progressive disease or physician decision to discontinue protocol therapy prior to completion of cycle 2; 17 [median age 13 (2-20) years] were evaluable for determination of MTD during dose escalation, 6 were enrolled on the PK cohort, of which 3 were evaluable to toxicity. At DL1, 2/5 patients experienced DLT (thrombocytopenia during cycle 1 (n = 1) and cycle 2 (n = 1)); at DL-1, 2/6 patients experienced DLT (thrombocytopenia in cycle 1); at DL-2, 1/6 patients experienced DLT (thrombocytopenia in cycle 1). PK expansion enrolled at DL-2 and 1/3 participants evaluable for toxicity had a DLT (mucositis). Overall, at DL-2, 2/9 patients (22%) had DLT. One patient with Ewing Sarcoma had a partial response and remained on study for 35 cycles; Patients (one each) with Ewing Sarcoma, Wilms Tumor, and Pineoblastoma had stable disease, ranging from 3-6 cycles. Conclusions: Thrombocytopenia was dose limiting for ABI-009 alone and in combination with temozolomide and irinotecan. The MTD for ABI-009 is 15mg/m2/dose days 1 and 8 in combination with 5 daily doses of temozolomide 125 mg/m2/dose and oral irinotecan 90 mg/m2/dose. One patient had a partial response, 3 patients had prolonged stable disease. Pharmacokinetics and pharmacodynamics are pending and will inform future trials. Clinical trial information: NCT02975882.

Design, Synthesis and Biological Evaluation of Novel 9-Methyl-9H-Purine and Thieno[3, 2-d]Pyrimidine Derivatives as Potent Mtor Inhibitors

Design, Synthesis and Biological Evaluation of Novel 9-Methyl-9H-Purine and Thieno[3, 2-d]Pyrimidine Derivatives as Potent Mtor Inhibitors

Fin56-induced ferroptosis is supported by autophagy-mediated GPX4 degradation and functions synergistically with mTOR inhibition to kill bladder cancer cells

Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant and dedifferentiating cancers. Although several lines of evidence suggest that ferroptosis is a type of autophagy-dependent cell death, the underlying molecular mechanisms remain unclear. Fin56, a type 3 ferroptosis inducer, triggers ferroptosis by promoting glutathione peroxidase 4 (GPX4) protein degradation via a not fully understood pathway. Here, we determined that Fin56 induces ferroptosis and autophagy in bladder cancer cells and that Fin56-triggered ferroptosis mechanistically depends on the autophagic machinery. Furthermore, we found that autophagy inhibition at different stages attenuates Fin56-induced oxidative stress and GPX4 degradation. Moreover, we investigated the effects of Fin56 in combination with Torin 2, a potent mTOR inhibitor used to activate autophagy, on cell viability. We found that Fin56 synergizes with Torin 2 in cytotoxicity against bladder cancer cells. Collectively, our findings not only support the concept that ferroptosis is a type of autophagy-dependent cell death but imply that the combined application of ferroptosis inducers and mTOR inhibitors is a promising approach to improve therapeutic options in the treatment of bladder cancer.

Transcriptomic links to muscle mass loss and declines in cumulative muscle protein synthesis during short-term disuse in healthy younger humans.

Muscle disuse leads to a rapid decline in muscle mass, with reduced muscle protein synthesis (MPS) considered the primary physiological mechanism. Here, we employed a systems biology approach to uncover molecular networks and key molecular candidates that quantitatively link to the degree of muscle atrophy and/or extent of decline in MPS during short-term disuse in humans. After consuming a bolus dose of deuterium oxide (D2 O; 3mL.kg-1 ), eight healthy males (22±2years) underwent 4days of unilateral lower-limb immobilization. Bilateral muscle biopsies were obtained post-intervention for RNA sequencing and D2 O-derived measurement of MPS, with thigh lean mass quantified using dual-energy X-ray absorptiometry. Application of weighted gene co-expression network analysis identified 15 distinct gene clusters ("modules") with an expression profile regulated by disuse and/or quantitatively connected to disuse-induced muscle mass or MPS changes. Module scans for candidate targets established an experimentally tractable set of candidate regulatory molecules (242 hub genes, 31 transcriptional regulators) associated with disuse-induced maladaptation, many themselves potently tied to disuse-induced reductions in muscle mass and/or MPS and, therefore, strong physiologically relevant candidates. Notably, we implicate a putative role for muscle protein breakdown-related molecular networks in impairing MPS during short-term disuse, and further establish DEPTOR (a potent mTOR inhibitor) as a critical mechanistic candidate of disuse driven MPS suppression in humans. Overall, these findings offer a strong benchmark for accelerating mechanistic understanding of short-term muscle disuse atrophy that may help expedite development of therapeutic interventions.

Everolimus attenuates glutamate-induced PC12 cells death

Background Glutamate-induced neuronal cell death plays a key role in neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. Some recent studies reported the potential immunomodulatory and neuroprotective properties of inhibitors of serine-threonine kinase, mTOR (mammalian target of rapamycin). However, no study was conducted about the neuroprotective potential of everolimus (EVR), a selective and potent mTOR inhibitor. Therefore, this study was planned to investigate whether EVR has protective effects against glutamate-induced toxicity in PC12 cells, which are used as model for neurons injury, and to elucidate the underlying mechanism. Methods PC12 cells were concurrently treated with glutamate (8 mM) and EVR (0-40 nM) for 24 h. Then, the cells viability, apoptosis rate, and apoptosis-related proteins (caspase-3, bax and bcl-2) were measured using MTT, annexin V/PI and immunoblotting assays. Results Analyzing the protective effect of different concentrations of EVR (0-40 nM) against glutamate-induced cytotoxicity revealed a significant increase in cell viability in co-treatment regimen (p < 0.01). Also, EVR (40 nM) significantly (p < 0.01) inhibited glutamate-induced apoptosis through depressing the elevation of bax/bcl-2 ratio and expression of cleaved caspase-3, concentration depend. Conclusion The results demonstrated, for the first time, that EVR could protect against glutamate-mediated PC12 cell death via inhibiting apoptosis.

Marine-Derived Natural Products as ATP-Competitive mTOR Kinase Inhibitors for Cancer Therapeutics.

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase portraying a quintessential role in cellular proliferation and survival. Aberrations in the mTOR signaling pathway have been reported in numerous cancers including thyroid, lung, gastric and ovarian cancer, thus making it a therapeutic target. To attain this objective, an in silico investigation was designed, employing a pharmacophore modeling approach. A structure-based pharmacophore (SBP) model exploiting the key features of a selective mTOR inhibitor, Torkinib directed at the ATP-binding pocket was generated. A Marine Natural Products (MNP) library was screened using SBP model as a query. The retrieved compounds after consequent drug-likeness filtration were subjected to molecular docking with mTOR, thus revealing four MNPs with better scores than Torkinib. Successive refinement via molecular dynamics simulations demonstrated that the hits formed crucial interactions with key residues of the pocket. Furthermore, the four identified hits exhibited good binding free energy scores through MM-PBSA calculations and the subsequent in silico toxicity assessments displayed three hits deemed essentially non-carcinogenic and non-mutagenic. The hits presented in this investigation could act as potent ATP-competitive mTOR inhibitors, representing a platform for the future discovery of drugs from marine natural origin.