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EVEROLIMUS – TEARING mTOR CASCADES

by Selleckchem | Mar 20 2012

The mTOR pathway

One of the more central proteins in the many sequences of pathways that regulate growth patterns in cellular system is the “mammalian target for rapamycin”. Discovered by accident during the screening of extracts from plant and bacterial origin for biological activity this protein has proved to be highly complex in its activity. In an initial investigation it was demonstrated that this protein was essential for life itself, murine models mutated to silence this protein genetically did not survive the embryonic stage. [1;2] Structurally this protein resembles a lipid kinase but it also demonstrates significant functions similar to the protein kinase super families [3]. This protein contains more than one binding domain demonstrating kinase activity. These domains can bind with several possible ligands which trigger several different pathways. The mTOR protein can initiate scaffold building for DNA repair, to regulate other pathways in gene transcription and growth processes and regulate its own activity. mTOR signaling can be indirect as a results of a pathway trigger but also direct from extracellular signals. [4].

Everolimus: Some Properties and important usages

Everolimus was developed in response to the clinical evidence supplied by Rapamycin. With resistance to rapamycin becoming more evident and therapeutically limiting the dimethoxy cyclohexane side chain on the 28 atom cyclic structure that makes up Rapamycin was altered to a 2-((2-methoxycyclohexyl)oxy)ethanol. Like Rapamycin Everolimus was determined to be a potent immunosuppressant and it is used extensively to suppress transplant rejection. Everolimus is manufactured by a semisythesis procedure from Rapamycin [6]. Everolimus is being developed by Novartis; it is marketed under the trade names of Afinitor, Zortress or Certican, but also researched under the code OSI-RAD001 or SDZ-RAD. The Everolimus structure is based on a polyketide class of natural compounds with a molecular weight of 958.224. Everolimus solubility in buffer preparations is at a maximum of 10-20 µM but Everolimus is soluble in both DMSO and ethanol to a maximum 100 mg/ml concentration. Everolimus is specifically targeted against the mTOR1 protein but not the mTOR2 protein with the Everolimus IC50 for mTOR1 in the 1 -2 nM range. Everolimus stability is programmed for its lyophilized form which is stable at -20^oC or below and can stored under these conditions for a maximum of 2 years. In solution Everolimus can be kept at -20°C for a maximum of 3 months with minimal thawing. It is advised that aliquots of solution are stored for daily use and remnants discarded rather than refrozen. Researchers can buy Everolimus a 50 mg vial from a variety of Everolimus suppliers although Everolimus cost is reliant on the supplier of the product. Everolimus price can range from $179 up to $800 for the sterilized product.

Everolimus: Clinical status

Everolimus is 1^st generation derivative of rapamycin that has been demonstrated to be an inhibitor of mTOR1 (FRAP1)[7] and also a substrate for CYP3A4[8]. With close similarity in structure to rapamycin Everolimus has been tested in a variety of different diseases but has proved successful as an immunosuppressor in Liver [9], Cardiac [10] and Kidney[11] transplant rejections in relation to graft vascular illness[12]. Everolimus clinical trials are extensive with various degrees of success and failure. In metastatic breast cancer [13-15] Everolimus is or has been trialed in combination with Erlotinib, Docetaxel[16], cisplatin and paclitaxel or Letrozole or Fulvestrant or Tratuzumab[17], initial phase 1 and II trials are showing promising results in the HER2 over expressing patient subgroup. In combination with Vatalanib, erlotinib[18] or Bevacizumab [18;19] and Panitumumab or Fluorouracil, or Capecitabine[20]or Leucovorin or cisplatin [21] or Panitumumab, and Oxaliplatin Everolimus has been investigated with regard to advanced solid tumors[22-24]( Everolimus, carcinoids). In metastatic melanoma, kidney cancer, colorectal cancer [19], Renal cell carcinoma [25;26], hepatocellular cancer [27] Everolimus is or has been investigated as a single agent or in combination with Bevacizumab[28], Sorafenib [29] or Lenalidomide. As a single agent or in combination with cisplatin or imatinib[30] Everolimus is or has been investigated in advanced gastric cancer (Everolimus gastric cancer) while in Kidney cancer Everolimus has been investigated as a single agent [31-36]. As a single agent or in combination with Gleevec and hydroxyurea[37] or in combination with Temozolamide[38] / Bevacizumab Everolimus has been investigated in gliosarcoma, Low grade Gliomas and glioblastoma multiforme. This is but a small sample of the investigation in which Everloimus has been trialed.

References

1. Gangloff YG, Mueller M et al. Disruption of the mouse mTOR gene leads to early postimplantation lethality and prohibits embryonic stem cell development. Mol Cell Biol 2004; 24(21):9508-9516.

2. Murakami M, Ichisaka T et al. mTOR is essential for growth and proliferation in early mouse embryos and embryonic stem cells. Mol Cell Biol 2004; 24(15):6710-6718.

3. Harris TE, Lawrence JC, Jr. TOR signaling. Sci STKE 2003; 2003(212):re15.

4. Caron E, Ghosh S et al. A comprehensive map of the mTOR signaling network. Mol Syst Biol 2010; 6:453.

5. Carraway H, Hidalgo M. New targets for therapy in breast cancer: mammalian target of rapamycin (mTOR) antagonists. Breast Cancer Res 2004; 6(5):219-224.

6. Kennedy J. Mutasynthesis, chemobiosynthesis, and back to semi-synthesis: combining synthetic chemistry and biosynthetic engineering for diversifying natural products. Nat Prod Rep 2008; 25(1):25-34.

7. Dumont FJ. Everolimus. Novartis. Curr Opin Investig Drugs 2001; 2(9):1220-1234.

8. Kuhn B, Jacobsen W et al. Metabolism of sirolimus and its derivative everolimus by cytochrome P450 3A4: insights from docking, molecular dynamics, and quantum chemical calculations. J Med Chem 2001; 44(12):2027-2034.

9. Bismuth B, Castel H et al. Primary sarcoma of the liver and transplantation: a case study and literature review. Rare Tumors 2009; 1(2):e31.

10. Kovarik JM, Eisen H et al. Everolimus in de novo cardiac transplantation: pharmacokinetics, therapeutic range, and influence on cyclosporine exposure. J Heart Lung Transplant 2003; 22(10):1117-1125.

11. Bouzas L, Hermida J et al. Determination of blood sirolimus concentrations in liver and kidney transplant recipients using the Innofluor fluorescence polarization immunoassay: comparison with the microparticle enzyme immunoassay and high-performance liquid chromatography-ultraviolet method. Ups J Med Sci 2009; 114(1):55-61.

12. Aull MJ. Chronic allograft nephropathy: pathogenesis and management of an important posttransplant complication. Prog Transplant 2004; 14(2):82-88.

13. Jerusalem G, Fasolo A et al. Phase I trial of oral mTOR inhibitor everolimus in combination with trastuzumab and vinorelbine in pre-treated patients with HER2-overexpressing metastatic breast cancer. Breast Cancer Res Treat 2011; 125(2):447-455.

14. Morrow PK, Wulf GM et al. Phase I/II study of trastuzumab in combination with everolimus (RAD001) in patients with HER2-overexpressing metastatic breast cancer who progressed on trastuzumab-based therapy. J Clin Oncol 2011; 29(23):3126-3132.

15. Baselga J, Semiglazov V et al. Phase II randomized study of neoadjuvant everolimus plus letrozole compared with placebo plus letrozole in patients with estrogen receptor-positive breast cancer. J Clin Oncol 2009; 27(16):2630-2637.

16. Moulder S, Gladish G et al. A phase 1 study of weekly everolimus (RAD001) in combination with docetaxel in patients with metastatic breast cancer. Cancer 2011.

17. Andre F, Campone M et al. Phase I study of everolimus plus weekly paclitaxel and trastuzumab in patients with metastatic breast cancer pretreated with trastuzumab. J Clin Oncol 2010; 28(34):5110-5115.

18. Bullock KE, Petros WP et al. A phase I study of bevacizumab (B) in combination with everolimus (E) and erlotinib (E) in advanced cancer (BEE). Cancer Chemother Pharmacol 2011; 67(2):465-474.

19. Altomare I, Bendell JC et al. A phase II trial of bevacizumab plus everolimus for patients with refractory metastatic colorectal cancer. Oncologist 2011; 16(8):1131-1137.

20. Deenen MJ, Klumpen HJ et al. Phase I and pharmacokinetic study of capecitabine and the oral mTOR inhibitor everolimus in patients with advanced solid malignancies. Invest New Drugs 2011.

21. Fury MG, Sherman E et al. A phase I study of daily everolimus plus low-dose weekly cisplatin for patients with advanced solid tumors. Cancer Chemother Pharmacol 2011.

22. Okamoto I, Doi T et al. Phase I clinical and pharmacokinetic study of RAD001 (everolimus) administered daily to Japanese patients with advanced solid tumors. Jpn J Clin Oncol 2010; 40(1):17-23.

23. O'Donnell A, Faivre S et al. Phase I pharmacokinetic and pharmacodynamic study of the oral mammalian target of rapamycin inhibitor everolimus in patients with advanced solid tumors. J Clin Oncol 2008; 26(10):1588-1595.

24. Fouladi M, Laningham F et al. Phase I study of everolimus in pediatric patients with refractory solid tumors. J Clin Oncol 2007; 25(30):4806-4812.

25. Agarwala SS, Case S. Everolimus (RAD001) in the treatment of advanced renal cell carcinoma: a review. Oncologist 2010; 15(3):236-245.

26. Amato RJ, Jac J et al. A phase 2 study with a daily regimen of the oral mTOR inhibitor RAD001 (everolimus) in patients with metastatic clear cell renal cell cancer. Cancer 2009; 115(11):2438-2446.

27. Zhu AX, Abrams TA et al. Phase 1/2 study of everolimus in advanced hepatocellular carcinoma. Cancer 2011; 117(22):5094-5102.

28. Hainsworth JD, Spigel DR et al. Phase II trial of bevacizumab and everolimus in patients with advanced renal cell carcinoma. J Clin Oncol 2010; 28(13):2131-2136.

29. Amato RJ, Flaherty AL et al. Phase I Trial of Everolimus Plus Sorafenib for Patients with Advanced Renal Cell Cancer. Clin Genitourin Cancer 2011.

30. Schoffski P, Reichardt P et al. A phase I-II study of everolimus (RAD001) in combination with imatinib in patients with imatinib-resistant gastrointestinal stromal tumors. Ann Oncol 2010; 21(10):1990-1998.

31. Di LG, Porta C et al. Toxicities of targeted therapy and their management in kidney cancer. Eur Urol 2011; 59(4):526-540.

32. Di LG, Buonerba C et al. The therapy of kidney cancer with biomolecular drugs. Cancer Treat Rev 2010; 36 Suppl 3:S16-S20.

33. Bohler T, Waiser J et al. Pharmacodynamic effects of everolimus on anti-CD3 antibody-stimulated T-lymphocyte proliferation and interleukin-10 synthesis in stable kidney-transplant patients. Cytokine 2008; 42(3):306-311.

34. Traynor K. New oral treatment for kidney cancer approved. Am J Health Syst Pharm 2009; 66(9):788.

35. Edelstein CL. Mammalian target of rapamycin and caspase inhibitors in polycystic kidney disease. Clin J Am Soc Nephrol 2008; 3(4):1219-1226.

36. Kapoor A. Inhibition of mTOR in kidney cancer. Curr Oncol 2009; 16 Suppl 1:S33-S39.

37. Kreisl TN, Lassman AB et al. A pilot study of everolimus and gefitinib in the treatment of recurrent glioblastoma (GBM). J Neurooncol 2009; 92(1):99-105.

38. Mason WP, Macneil M et al. A phase I study of temozolomide and everolimus (RAD001) in patients with newly diagnosed and progressive glioblastoma either receiving or not receiving enzyme-inducing anticonvulsants: an NCIC CTG study. Invest New Drugs 2011.