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Background and Objective The inhibition of fatty acid amide hydrolase 1 (FAAH) has been proposed as a novel mechanism for treating pain syndromes by increasing the levels of endogenous cannabinoids (ECs). This study describes the safety, tolerability, pharmacokinetics and pharmacodynamics of V158866, a reversible FAAH inhibitor, after first administration to man. Methods 51 healthy male subjects were recruited into this double-blind, randomised, placebo-controlled, adaptive dose, phase I single (Part A) and repeated ascending dose (Part B) study. The primary outcome was the safety and tolerability of V158866. Secondary outcomes were (1) pharmacokinetics of V158866 and (2) pharmacodynamics of V158866, as assessed by changes in plasma EC concentrations. Results Single oral doses of 5–300 mg and repeated oral doses of 50–500 mg were evaluated. V158866 was well tolerated, with no apparent treatment-related effects on laboratory variables. V158866 was rapidly absorbed with a mean terminal elimination half-life of 9.6–18.3 h (Day 7; Part B). V158866 reached steady state within 2–3 days of administration, with an accumulation ratio, based on AUC0–24h, of approximately 2 on Day 7. V158866 showed a linear relationship between dose and AUC across the entire dose range. V158866 caused reversible, dose-related increases in plasma ECs. At hemi-equilibrium, there was a sigmoidal maximum effect relationship between plasma V158866 concentrations and changes in plasma ECs. Conclusions V158866 is well tolerated, with linear pharmacokinetics suitable for once-daily administration, and reversible effects on plasma ECs. Maximum increases in plasma ECs occur with V158866 doses of 300–500 mg/day. Electronic supplementary material The online version of this article (doi:10.1007/s40268-016-0127-y) contains supplementary material, which is available to authorized users.

The anti-apoptotic function of the 70 kDa family of heat shock proteins and their role in cancer is well documented. Dual targeting of Hsc70 and Hsp70 with siRNA induces proteasome-dependent degradation of Hsp90 client proteins and extensive tumor specific apoptosis as well as the potentiation of tumor cell apoptosis following pharmacological Hsp90 inhibition.We have previously described the discovery and synthesis of novel adenosine-derived inhibitors of the 70 kDa family of heat shock proteins; the first inhibitors described to target the ATPase binding domain. The in vitro activity of VER-155008 was evaluated in HCT116, HT29, BT474 and MDA-MB-468 carcinoma cell lines. Cell proliferation, cell apoptosis and caspase 3/7 activity was determined for VER-155008 in the absence or presence of small molecule Hsp90 inhibitors.VER-155008 inhibited the proliferation of human breast and colon cancer cell lines with GI(50)s in the range 5.3-14.4 microM, and induced Hsp90 client protein degradation in both HCT116 and BT474 cells. As a single agent, VER-155008 induced caspase-3/7 dependent apoptosis in BT474 cells and non-caspase dependent cell death in HCT116 cells. VER-155008 potentiated the apoptotic potential of a small molecule Hsp90 inhibitor in HCT116 but not HT29 or MDA-MB-468 cells. In vivo, VER-155008 demonstrated rapid metabolism and clearance, along with tumor levels below the predicted pharmacologically active level.These data suggest that small molecule inhibitors of Hsc70/Hsp70 phenotypically mimic the cellular mode of action of a small molecule Hsp90 inhibitor and can potentiate the apoptotic potential of a small molecule Hsp90 inhibitor in certain cell lines. The factors determining whether or not cells apoptose in response to Hsp90 inhibition or the combination of Hsp90 plus Hsc70/Hsp70 inhibition remain to be determined.

// Andrew J. Massey 1 , Stephen Stokes 1 , Helen Browne 1 , Nicolas Foloppe 1 , Andrea Fiumana 1 , Simon Scrace 1,3 , Mandy Fallowfield 1 , Simon Bedford 1 , Paul Webb 1 , Lisa Baker 1 , Mark Christie 2 , Martin J. Drysdale 1,4 and Mike Wood 1 1 Vernalis Research, Granta Park, Cambridge, UK 2 Akranim Ltd, Maidstone, UK 3 Horizon Discovery, Cambridge Research Park, Waterbeach, Cambridge, UK 4 Cancer Research UK Beatson Institute, Garscube Estate, Bearsden, Glasgow, UK Correspondence to: Andrew J. Massey, email: // Keywords : Chk1, V158411, fragment, drug discovery, colon cancer Received : June 17, 2015 Accepted : September 14, 2015 Published : September 30, 2015 Abstract Chk1 kinase is a critical component of the DNA damage response checkpoint especially in cancer cells and targeting Chk1 is a potential therapeutic opportunity for potentiating the anti-tumor activity of DNA damaging chemotherapy drugs. Fragment elaboration by structure guided design was utilized to identify and develop a novel series of Chk1 inhibitors culminating in the identification of V158411, a potent ATP-competitive inhibitor of the Chk1 and Chk2 kinases. V158411 abrogated gemcitabine and camptothecin induced cell cycle checkpoints, resulting in the expected modulation of cell cycle proteins and increased cell death in cancer cells. V158411 potentiated the cytotoxicity of gemcitabine, cisplatin, SN38 and camptothecin in a variety of p53 deficient human tumor cell lines in vitro , p53 proficient cells were unaffected. In nude mice, V158411 showed minimal toxicity as a single agent and in combination with irinotecan. In tumor bearing animals, V158411 was detected at high levels in the tumor with a long elimination half-life; no pharmacologically significant in vivo drug-drug interactions with irinotecan were identified through analysis of the pharmacokinetic profiles. V158411 potentiated the anti-tumor activity of irinotecan in a variety of human colon tumor xenograft models without additional systemic toxicity. These results demonstrate the opportunity for combining V158411 with standard of care chemotherapeutic agents to potentiate the therapeutic efficacy of these agents without increasing their toxicity to normal cells. Thus, V158411 would warrant further clinical evaluation.

Conventional chemotherapeutic agents such as gemcitabine, cisplatin or irinotecan induce DNA damage and activate cell cycle checkpoints. P53 defective tumors lack a functional G1 checkpoint and rely heavily on the S and G2 checkpoints, and the effector kinase Chk1, for protection against this DNA damage. Inhibiting Chk1 potentiates the anti-tumor effects of these cytotoxic chemotherapeutic agents. Targeting Chk1 is a potential therapeutic opportunity for potentiating the anti-tumor efficacy of DNA damaging cytotoxic chemotherapeutic drugs without increasing their toxicity to normal cells. Elaboration of a designed kinase directed fragment core utilizing X-ray structure guided design lead to the identification of a potent pyridone series of Chk1 inhibitors. Further profiling identified V158411 as the lead candidate. X-ray crystallography identified V158411 as being bound to the ATPase site in the kinase domain of Chk1. V158411 potently inhibited Chk1 and Chk2 with IC50s of 4.4 and 4.5nM respectively. The addition of V158411 to gemcitabine or camptothecin treated cells abrogated the cell cycle checkpoints induced by these agents resulting in the expected modulation of cell cycle proteins and increased apoptosis. V158411 potentiated the cytotoxicity of gemcitabine, cisplatin, SN38 and camptothecin in a variety of p53 deficient but not proficient human tumor cell lines in vitro. V158411 could be formulated in a simple aqueous form suitable for i.v. dosing. In nude mice, V158411 was well tolerated as a single agent (MTD >100mg/kg) and in combination with irinotecan. Intravenous administration to rats and mice resulted in low plasma clearances (20mL/min/kg) and long half-lives (2.9–3.7h). In tumor bearing animals, V158411 was detected at high concentrations in the tumor (tumor:plasma AUC ratio of 4.7) with a long tumor elimination half life of 22 hours. No pharmacologically relevant in vivo drug-drug interaction with irinotecan was identified. V158411 potentiated the anti-tumor activity of gemcitabine and irinotecan in a variety of human tumor xenograft models without additional systemic toxicity. These results demonstrate the potential of combining V158411 with standard of care chemotherapeutic agents to potentiate the therapeutic efficacy of these agents without increasing their toxicity to normal cells. Based on this data, the clinical development of V158411 is currently being actively pursued. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C207.