Palomid 529

Palomid 529 (P529) is a novel potent antitumour PI3K/Akt/mTOR inhibitor with a GI50 of <35 μM in the NCI-60 cell lines panel.[1] Palomid 529 inhibits both VEGF-driven and bFGF-driven endothelial cell proliferation with IC50 of 20 nM and 30 nM, respectively.
PI3K activates AKT,then AKT activate CREB,inhibit p27locate FOXO in the cytoplasm, activate PtdIns-3ps, and mTOR which can effect transcription of p70 or 4EBP1.[2,3]
In many cancers, this pathway is overactive, thus reducing apoptosis and allowing proliferation. This pathway is necessary, however, to promote growth and proliferation over differentiation of adult stem cells, neural stem cells specifically. Additionally, this pathway has been found to a be a necessary component in neural long term potentiation.[4]Lowering the effect of the PI3K pathway and increasing the effect of GSK3β and HB9 in NSCs is a potential way of generating these cells better for survival of the neurons. Amplifying the PI3K/AKT pathway increases this neural outgrowth which can determine appropriate treatment concentrations of bisperoxovanadium to stimulate axonal outgrowth but not cause cancer.Not only Palomid 529 inhibits radiation-induced overexpression of Id-1 and VEGF, but also down-regulates radiation-induced MMP-2 and MMP-9. [5]
Reference:
1 Xue Q, et al. “Palomid 529, a novel small-molecule drug, is a TORC1/TORC2 inhibitor that reduces tumor growth, tumor angiogenesis, and vascular permeability.” Cancer Res, 2008, 68(22), 9551-9557.
2 Rafalski, V. A.; Brunet, A. "Energy metabolism in adult neural stem cell fate". Progress in Neurobiology . 2011, 93 (2): 182–203.
3 Ojeda, L. et al. "Critical role of PI3K/Akt/GSK3β in motoneuron specification from human neural stem cells in response to FGF2 and EGF". PLoS ONE 2011, 6 (8): e23414.
4 Sui, L; Wang, J; Li, B. M. "Role of the phosphoinositide 3-kinase-Akt-mammalian target of the rapamycin signaling pathway in long-term potentiation and trace fear conditioning memory in rat medial prefrontal cortex". Learning & Memory 2008,15 (10): 762–76.
5 Diaz R, et al. “The novel Akt inhibitor Palomid 529 (P529) enhances the effect of radiotherapy in prostate cancer” .Br J Cancer 2009, 100(6), 932-940.

Subconjunctival Palomid 529 in the treatment of neovascular age-related macular degeneration.[Pubmed:23689994]

Graefes Arch Clin Exp Ophthalmol. 2013 Dec;251(12):2705-9.

BACKGROUND: Recent evidence suggests that neovascular age-related macular degeneration (AMD) may have an immune mediated component. Palomid 529, an investigational medication involving the immune Akt/mTOR pathway, is unique in dissociating both targets of rapamycin complexes TORC1 and TORC2. This small short-term pilot study assesses the safety of subconjunctival Palomid 529 in the treatment of neovascular AMD, with some limited efficacy information. METHODS: In this 12-week phase I open-label prospective pilot study, five participants with neovascular age-related macular degeneration that were refractory to intravitreal anti-vascular endothelial growth factor (VEGF) received three serial monthly subconjunctival doses of 1.9 mg Palomid 529. All participants were also offered concomitant monthly intravitreal anti-VEGF injections. Safety was monitored via adverse events recording. Additional outcome measures included visual acuity, optical coherence tomography, fluorescein angiography, indocyanine green angiography and fundus photography. RESULTS: The study drug was well-tolerated by all participants. There were no drug-related adverse events and no serious adverse events. A depot formed at the injection site, which persisted at the end of the study. In these anti-VEGF refractory patients, no clinically important changes in best-corrected visual acuity, fluorescein leakage pattern, choroidal neovascularization size on indocyanine green angiography, or autofluorescence pattern on fundus autofluorescence were observed compared to baseline. The fluid status, assessed with optical coherence tomography showed that central retinal thickness and macular volume remained stable in three participants, while the other two participants clinically progressed. CONCLUSIONS: Serial subconjunctival injections of Palomid 529 were well-tolerated and resulted in depot formation. There were no concerns for any ocular or systemic toxicity during this small short-term study. Larger randomized studies are required to determine efficacy.

Torc1/Torc2 inhibitor, Palomid 529, enhances radiation response modulating CRM1-mediated survivin function and delaying DNA repair in prostate cancer models.[Pubmed:24715588]

Prostate. 2014 Jun;74(8):852-68.

BACKGROUND: P529, a Torc1/Torc2 inhibitor, has demonstrated its potential as a radiosensitizer. However the molecular mechanisms underlying this phenomenon still need to be elucidated. Aim of this study is to dissect molecular mechanisms regulating the radiosensitizing properties of P529 in a wide panel of prostate cancer models. METHODS: Six tumor cell lines and xenograft models were used for in vitro and in vivo studies. Clonogenic survival, apoptotic, autophagic, and senescence assays were used to examine the effects of ionizing radiation (IR) alone and in combination with P529. CRM1, survivin, GSK-3beta, and DNA-DSBs expression and modulation, upon P529 and RT, were monitored by western blot. In vivo treatment response upon P529, irradiation or combination of P529 with IR was monitored by tumor volume, time to progression (TTP), and immunohistochemical analysis. RESULTS: P529 treatment induced significantly more apoptosis and DNA double-strand break (DSB) when combined with radiotherapy resulting in cellular radiosensitization and growth delay of irradiated tumor xenografts. Upon P529 treatment Rad51, DNA-PKcs, and Ku70 protein expression was downregulated, indicating delayed DNA double-strand damage repair. The radiosensitizing properties of P529 were partially linked to GSK-3beta, cyclin-D1, and c-myc modulation with associated inhibition of CRM1-mediated nuclear export of survivin. Importantly, autophagy and tumor senescence were involved in the enhanced P529 radioresponse. CONCLUSIONS: Impaired DNA double-strand damage repair, inhibition of CRM1-mediated nuclear export of survivin, modulation of cyclin-D1 and c-myc with associated pro-apoptotic and autophagic and senescent events explain the radiosensitizing properties of P529 in preclinical models of prostate cancer.

Dual mTORC1 and mTORC2 inhibitor Palomid 529 penetrates the blood-brain barrier without restriction by ABCB1 and ABCG2.[Pubmed:23436212]

Int J Cancer. 2013 Sep 1;133(5):1222-33.

Palomid 529, a novel dual mTORC1/2 inhibitor has displayed interesting activities in experimental models and is a candidate for clinical evaluation. We have assessed the interaction of Palomid 529 with ATP-binding cassette (ABC) drug efflux transporters ABCB1 (P-gp/P-glycoprotein) and ABCG2 (BCRP/Breast Cancer Resistant Protein) by in vitro transwell assays, and their effects on the brain penetration using drug disposition analysis of i.v. and oral Palomid 529 in wild-type (WT) and Abcb1 and/or Abcg2 knockout (KO) mice. Palomid 529 lacked affinity for these transporters in vitro, in contrast to GDC-0941, a small molecule PI3K inhibitor, which we used as control substance for in vitro transport. The plasma AUCi.v. of micronized and DMSO formulated Palomid 529 was similar in WT and KO mice. Importantly, the brain and brain tumor concentration of Palomid 529 at a high dose (54 mg/kg) was also similar in both strains, whereas a less than 1.4-fold difference (p < 0.05) was found at the low (5.4 mg/kg) dose. Because of poor solubility, the oral bioavailability of micronized Palomid 529 was only 5%. Olive oil or spray-dried formulation greatly improved the bioavailability up to 50%. Finally, Palomid 529 effectively inhibits the orthotopic U87 glioblastoma growth. In summary, Palomid 529 is the first mTOR targeting drug lacking affinity for ABCB1/ABCG2 and having good brain penetration. This warrants further evaluation of Palomid 529 for treatment of high-grade gliomas and other intracranial malignancies.

High-performance liquid chromatography analysis of a novel small-molecule, anti-cancer drug, Palomid 529, in human and mouse plasma and in mouse tissue homogenates.[Pubmed:22100549]

J Chromatogr B Analyt Technol Biomed Life Sci. 2011 Dec 15;879(32):3823-31.

Palomid 529 (8-(1-Hydroxy-ethyl)-2-methoxy-3-(4-methoxy-benzyloxy)-benzo[c]chromen-6-one), is a novel non-steroidal small-molecule drug, which inhibits both mTORC1 and mTORC2 assembly, and elicits both anti-angiogenic and direct anti-tumor effects in vivo. We have developed and validated a sensitive and selective method for the quantification of Palomid 529 in human and mouse plasma and in a range of mouse tissue samples. Sample pretreatment involved liquid-liquid extraction with tert-butyl methyl ether yielding a recovery of >75%. Palomid 529 and the internal standard Palomid 545 were separated using a GraceSmart RP18 column (2.1 mm x 150 mm) packed with 5 mum C-18 material and a mobile phase comprised of 50% (v/v) acetonitrile and 50% (v/v) water delivered at a flow rate of 0.2 ml/min, and were detected by UV absorbance at a wavelength of 315 nm. Within the linear range of the calibration curve (10-10,000 ng/ml), acceptable accuracy and precision was achieved for all tested matrices. The validation results show that the method was selective and reproducible. Palomid 529 was stable in plasma upon 3 repeated freeze-thaw cycles and during storage for up to 24h at ambient temperature. However, pre-treated samples waiting for HPLC analyses need to be kept under dimmed light conditions at ambient temperature since a significant degradation of both Palomid 529 and Palomid 545 was observed when exposed to light. A pilot pharmacokinetic study in mice demonstrated the applicability of this method for pharmacokinetic purposes. Even at a low dose of 5.4 mg/kg this assay was still sensitive enough to determine the drug concentration in plasma samples obtained up to 24h after administration.