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Purpose: The aim of this study was to show preclinical efficacy and clinical development potential of PKI-587, a dual phosphoinositide 3-kinase (PI3K)/mTOR inhibitor.Experimental Design: In vitro class 1 PI3K enzyme and human tumor cell growth inhibition assays and in vivo five tumor xenograft models were used to show efficacy.Results: In vitro, PKI-587 potently inhibited class I PI3Ks (IC50 vs. PI3K-α = 0.4 nmol/L), PI3K-α mutants, and mTOR. PKI-587 inhibited growth of 50 diverse human tumor cell lines at IC50 values of less than 100 nmol/L. PKI-587 suppressed phosphorylation of PI3K/mTOR effectors (e.g., Akt), and induced apoptosis in human tumor cell lines with elevated PI3K/mTOR signaling. MDA-MB-361 [breast; HER2+, PIK3CA mutant (E545K)] was particularly sensitive to this effect, with cleaved PARP, an apoptosis marker, induced by 30 nmol/L PKI-587 at 4 hours.In vivo, PKI-587 inhibited tumor growth in breast (MDA-MB-361, BT474), colon (HCT116), lung (H1975), and glioma (U87MG) xenograft models. In MDA-MB-361 tumors, PKI-587 (25 mg/kg, single dose i.v.) suppressed Akt phosphorylation [at threonine(T)308 and serine(S)473] for up to 36 hours, with cleaved PARP (cPARP) evident up to 18 hours. PKI-587 at 25 mg/kg (once weekly) shrank large (∼1,000 mm3) MDA-MB-361 tumors and suppressed tumor regrowth. Tumor regression correlated with suppression of phosphorylated Akt in the MDA-MB-361 model. PKI-587 also caused regression in other tumor models, and efficacy was enhanced when given in combination with PD0325901 (MEK 1/2 inhibitor), irinotecan (topoisomerase I inhibitor), or HKI-272 (neratinib, HER2 inhibitor).Conclusion: Significant antitumor efficacy and a favorable pharmacokinetic/safety profile justified phase 1 clinical evaluation of PKI-587. Clin Cancer Res; 17(10); 3193–203. ©2011 AACR.

Supplementary Figures S1-S10; Supplementary Tables S1-S5.

This was a single-dose, one-period, multicenter, pharmacokinetic (PK) study to evaluate the PK of methylphenidate (MPH) hydrochloride multilayer extended-release capsules (MPH-MLR) in preschool children aged 4 to

Objective This was a single-dose, one-period, multicenter, pharmacokinetic (PK) study to evaluate the PK of methylphenidate (MPH) hydrochloride multilayer extended-release capsules (MPH-MLR) in preschool children aged 4 to

The mammalian target of rapamycin (mTOR) has proven to be a valid therapeutic target in a number of human cancers, and it is a candidate for clinical trials in human breast cancer. We report on a biomarker-based translational medicine approach to assess the efficacy and mechanism of action for the mTOR inhibitor temsirolimus (CCI-779) in a mammary carcinoma OncoMouse model [polyomavirus middle T antigen (PyMT)]. The mTOR signaling pathway biomarkers were assessed using a reverse-phase protein array. Pharmacokinetics studies were conducted in both the tumor and plasma compartments. Pharmacodynamic biomarkers for compound-target engagement of tumor phospho-S6 proteins were assayed by Western blot. Temsirolimus (intravenously once a week for 2 weeks) was administered in both early and advanced stages of tumors. Biomarkers for temsirolimus effects on tumor progression were assessed by three-dimensional ultrasound imaging in combination with immunohistochemistry to assess vascular density (Texas red-dextran and CD31 immunostaining) and macrophage burden (F4/80 antigen). Tumor growth was significantly arrested in temsirolimus (25 ± 14% from 8 to 10 weeks, p < 0.05, and 26 ± 17% from 11 to 13 weeks, p < 0.01), compared with 493 ± 160 and 376 ± 50% increases, respectively, in vehicle-treated groups. Temsirolimus reduced tumor vascular density, 36 to 48 and 58 to 60%, p < 0.05, by the Texas red-dextran method or CD31-positive vessel count, respectively. Temsirolimus reduced tumor macrophage burden by 46% at 13 weeks (p < 0.05). Temsirolimus inhibited (p < 0.05) the phosphoproteins S6 pS235/236 and S6 pS240/244 up to 81 and 87%, respectively. We conclude that the multimodal biomarkers of temsirolimus efficacy and mechanism of action (phosphoproteins) strongly suggest that it might translate to therapeutic efficacy in human tumors that bear congruency to features present in the mammary carcinoma of PyMT tumors.

It is important to gain an understanding of the pharmacological activities of metabolite(s) of compounds in development, especially if they are found in systemic circulation in humans. Pharmacological evaluation of metabolites is normally conducted with synthetic standards, which become available during various stages of drug development. However, the synthesis of metabolite standards may be protracted, taking anywhere from several weeks to months to be completed. This often slows down early pharmacological evaluation of metabolites. Once a metabolite(s) is found to possess comparable (or greater) pharmacological activity than the parent compound, additional studies are performed to better understand the implications of circulating pharmacologically active metabolite(s). To conduct some of these studies as early as possible without slowing the progression of a compound in development is important, especially if critical go or no-go decisions impinge on the outcomes from these studies. Early pharmacological evaluation of significant metabolites is hereby proposed to be conducted in the drug discovery stage so that all pertinent studies and information can be gathered in a timely manner for decision-making. It is suggested that these major metabolites be isolated, either from biological or chemical sources, and quantified appropriately. For biologically generated metabolites, NMR is proposed as the tool of choice to quantitate these metabolites before their evaluation in pharmacological assays. For metabolites that have the same UV characteristics as the parent compound, quantitation can be conducted using UV spectroscopy instead of NMR. In this article, we propose a strategy that could be used to determine the pharmacological activities of metabolites isolated in submilligram quantities.

The 7-alkene-3-quinolinecarbonitrile 20, a potent inhibitor of Src enzymatic and cellular activity with IC50 values of 2.1 and 58 nM, respectively, had comparable efficacy to bosutinib in a colon tumor xenograft study.

The PI3K/Akt signaling pathway is a key pathway in cell proliferation, growth, survival, protein synthesis, and glucose metabolism. It has been recognized recently that inhibiting this pathway might provide a viable therapy for cancer. A series of bis(morpholino-1,3,5-triazine) derivatives were prepared and optimized to provide the highly efficacious PI3K/mTOR inhibitor 1-(4-{[4-(dimethylamino)piperidin-1-yl]carbonyl}phenyl)-3-[4-(4,6-dimorpholin-4-yl-1,3,5-triazin-2-yl)phenyl]urea 26 (PKI-587). Compound 26 has shown excellent activity in vitro and in vivo, with antitumor efficacy in both subcutaneous and orthotopic xenograft tumor models when administered intravenously. The structure-activity relationships and the in vitro and in vivo activity of analogues in this series are described.

We are introducing a novel series of 2,4-diaminoquinazolines as beta-catenin/Tcf4 inhibitors which were identified by ligand-based design. Here we elucidate the SAR of this series and explain how we were able to improve key molecular properties such as solubility and cLogP leading to compound 9. Analogue 9 exhibited better biological activity and improved physical and pharmacological properties relative to the HTS hit 49. Furthermore, 9 demonstrated good cell growth inhibition against several human colorectal cancer lines such as LoVo and HT29. In addition, treatment with compound 9 led to gene expression changes that overlapped significantly with the transcriptional profile resulting from the pathway inhibition by siRNA knockdown of beta-catenin or Tcf4. Subsequently, 9 was tested for efficacy in a beta-catenin/RKE-mouse xenograft, where it led to more then 50% decrease in tumor volume.

Herein we describe the identification and lead optimization of triazolopyrimidines as a novel class of potent dual PI3K/mTOR inhibitors, resulting in the discovery of 3 (PKI-402). Compound 3 exhibits good physical properties and PK parameters, low nanomolar potency against PI3Kalpha and mTOR, and excellent inhibition of cell proliferation in several human cancer cell lines. Furthermore, in vitro and in vivo biomarker studies demonstrated the ability of 3 to shut down the PI3K/Akt pathway and induce apoptosis in cancer cells. In addition, 3 showed excellent in vivo efficacy in various human cancer xenografts, validating suppression of PI3K/mTOR signaling as a potential anticancer therapy.

Hyperactivation of the PI3K/AKT/mTOR signaling pathway is common in cancer, and PI3K and mTOR act synergistically in promoting tumor growth, survival, and resistance to chemotherapy. Thus, combined targeting of PI3K and mTOR presents an opportunity for robust and synergistic anticancer efficacy. 17-Hydroxywortmannin (2a) analogues conjugated to rapamycin (3a) analogues via a prodrug linker are uniquely positioned for this approach. Our efforts led to the discovery of diester-linked conjugates that, upon in vivo hydrolysis, released two highly potent inhibitors. Conjugate 7c provided enhanced solubility relative to 3a and to an equivalent mixture of 3a and 9a and demonstrated profound activity in U87MG mouse xenografts, achieving an MED of 1.5 mg/kg, following weekly intravenous dosing. At 15 mg/kg, 7c completely inhibited the growth of HT29 tumors, whereas an equivalent mixture of the inhibitors was poorly tolerated. In the A498 renal tumor model, 7c exhibited superior efficacy over 3a or 9a when administered as a single agent or in combination with bevacizumab. Thus, we have uncovered a novel approach to target both PI3K and mTOR via hybrid inhibitors, leading to a broader and more robust anticancer efficacy.

The synthesis and SAR of a series of 2,4-diamino-quinazoline derivatives as beta-catenin/Tcf-4 inhibitors are described. This series was developed by modifying the initial lead 1, which was identified by screening of our compound library and found to inhibit the beta-catenin/Tcf-4 pathway. Replacement of the biphenyl moiety in compound 1 with the N-phenylpiperidine-4-carboxamide chain as in 2, resulted in a number of new analogues, which are potent inhibitors of the beta-catenin/Tcf-4 pathway. Compound such as 16k exhibited good cellular potency, solubility, metabolic stability and oral bioavailability.

The present study aims to establish a method that provides fast, precise and reproducible pharmacokinetic (PK) parameters of antibody-calicheamicin conjugates. The method should discriminate between PK of the antibody moiety and PK of the conjugated calicheamicin (CM). The conjugates gemtuzumab ozogamicin (CMA-676, Mylotarg®) or inotuzumab ozogamicin (CMC-544) were injected in the tail vein of nude mice. At regular time intervals, 5 μl whole blood samples were taken from the tail artery. Concentrations of conjugated CMA-676 or CMC-544 as well as concentrations of their respective antibody moiety were determined by sandwich plasmon resonance. This detection system measures changes in the plasma resonance angle caused by the interaction of macromolecules on biosensor chips. We determined as a first measure the binding of CMA-676 or CMC-544 to their respective antigens, CD33 or CD22. As a second measure we determined the amount of CM on the antigen-bound conjugates. This was done by determination of changes in plasma resonance angle after binding of an anti-CM antibody. Sandwich plasmon resonance allowed detection of both conjugates in blood of mice in a range of 100–1,000 ng/ml protein. Due to the precision of the sampling and detection methods, PK values of each conjugate were determined in individual mice. Calicheamicin bound to antibody was eliminated faster than the antibody alone. The presence of a CD22-expressing tumour in mice reduced the plasma levels of the CD22-targeting conjugate but not of the CD33-targeting one. Using small blood samples from a mouse, the sandwich plasmon resonance method provided PK-values of CM-conjugates and information about the stability of the linkage in vivo. Comparison between the PK-values of CM-conjugates in tumour-bearing and tumour-free mice suggested that retention of the conjugate in tumour tissue due to antigen targeting could be deduced from the plasma levels.

Src up-regulation is a common event in human cancers. In colorectal cancer, increased Src levels are an indicator of poor prognosis, and progression to metastatic disease is associated with substantial increases in Src activity. Therefore, we examined the activity of SKI-606, a potent inhibitor of Src and Abl kinases, against colon tumor lines in vitro and in s.c. tumor xenograft models. SKI-606 inhibited Src autophosphorylation with an IC50 of ∼0.25 μmol/L in HT29 cells. Phosphorylation of Tyr925 of focal adhesion kinase, a Src substrate, was reduced by similar concentrations of inhibitor. Antiproliferative activity on plastic did not correlate with Src inhibition in either HT29 or Colo205 cells (IC50s, 1.5 and 2.5 μmol/L, respectively), although submicromolar concentrations of SKI-606 inhibited HT29 cell colony formation in soft agar. SKI-606 also caused loosely aggregated Colo205 spheroids to condense into compact spheroids. On oral administration to nude mice at the lowest efficacious dose, peak plasma concentrations of ∼3 μmol/L, an oral bioavailability of 18%, and a t1/2 of 8.6 hours were observed. SKI-606 was orally active in s.c. colon tumor xenograft models and caused substantial reductions in Src autophosphorylation on Tyr418 in HT29 and Colo205 tumors. SKI-606 inhibited HT29 tumor growth on once daily administration, whereas twice daily administration was necessary to inhibit Colo205, HCT116, and DLD1 tumor growth. These results support development of SKI-606 as a therapeutic agent for treatment of colorectal cancer.

Purpose: The aim of this study was to show preclinical efficacy and clinical development potential of PKI-587, a dual phosphoinositide 3-kinase (PI3K)/mTOR inhibitor. Experimental Design: In vitro class 1 PI3K enzyme and human tumor cell growth inhibition assays and in vivo five tumor xenograft models were used to show efficacy. Results: In vitro, PKI-587 potently inhibited class I PI3Ks (IC50 vs. PI3K-α = 0.4 nmol/L), PI3K-α mutants, and mTOR. PKI-587 inhibited growth of 50 diverse human tumor cell lines at IC50 values of less than 100 nmol/L. PKI-587 suppressed phosphorylation of PI3K/mTOR effectors (e.g., Akt), and induced apoptosis in human tumor cell lines with elevated PI3K/mTOR signaling. MDA-MB-361 [breast; HER2+, PIK3CA mutant (E545K)] was particularly sensitive to this effect, with cleaved PARP, an apoptosis marker, induced by 30 nmol/L PKI-587 at 4 hours. In vivo, PKI-587 inhibited tumor growth in breast (MDA-MB-361, BT474), colon (HCT116), lung (H1975), and glioma (U87MG) xenograft models. In MDA-MB-361 tumors, PKI-587 (25 mg/kg, single dose i.v.) suppressed Akt phosphorylation [at threonine(T)308 and serine(S)473] for up to 36 hours, with cleaved PARP (cPARP) evident up to 18 hours. PKI-587 at 25 mg/kg (once weekly) shrank large (∼1,000 mm3) MDA-MB-361 tumors and suppressed tumor regrowth. Tumor regression correlated with suppression of phosphorylated Akt in the MDA-MB-361 model. PKI-587 also caused regression in other tumor models, and efficacy was enhanced when given in combination with PD0325901 (MEK 1/2 inhibitor), irinotecan (topoisomerase I inhibitor), or HKI-272 (neratinib, HER2 inhibitor). Conclusion: Significant antitumor efficacy and a favorable pharmacokinetic/safety profile justified phase 1 clinical evaluation of PKI-587. Clin Cancer Res; 17(10); 3193–203. ©2011 AACR.

The present study describes the mechanism of the dampened induction of the CYP2B1 and CYP2B2 genes following phenobarbital treatment in the phenotypically obese fa/fa Zucker rat. The fa/fa Zucker rat demonstrated a threefold lower level of CYP2B1/2B2 enzyme induction, as indicated by reduced testosterone oxidation at the 16β position and resorufin formation from pentoxy- and benzyloxyresorufin, protein concentration (Western blot analysis), and steady-state mRNA levels (Northern and slot blot analyses) following in vivo treatment with phenobarbital than the Fa/? littermate controls. A primary hepatocyte cell culture system was used to determine if the dampened induction of the CYP2B1/2B2 enzyme is dependent on hormonal influences. Phenobarbital-treated (0.75 mM) hepatocytes from fa/fa Zucker rats showed approximately a three-fold lower induction response based on measurements of CYP2B1/2B2 (R-17 cDNA probe) and CYP2B1 (oligo probe) mRNAs. In order to evaluate whether this dampened response was at the level of transcriptional activation or initiation, as opposed to altered message stability, we measured the rate of transcription of CYP2B1/2B2 genes in nuclei from cultured hepatocytes during run-off experiments. Compared to Fa/? controls, the fa/fa Zucker rat had a greater than threefold lower nuclear transcription rate of CYP2B1/2B2 mRNA. These results suggest that the defective induction of the CYP2B1 and CYP2B2 genes exists at the transcriptional level in the mutant obese fa/fa Zucker rat. These data provide strong evidence that at least two genes are involved. Multiple gene involvement would suggest that the defect is not due to a mutation of the CYP2B gene cis -acting sequence. Instead, the lack of binding of a trans -acting factor, the presence of a repressor, or a defect in transcriptional activation is more likely the molecular mechanism(s) for this enzyme induction defect.

The 7-alkene-3-quinolinecarbonitrile 20, a potent inhibitor of Src enzymatic and cellular activity with IC50 values of 2.1 and 58 nM, respectively, had comparable efficacy to bosutinib in a colon tumor xenograft study.

A series of mono-morpholino 1,3,5-triazine derivatives (8a-8q) bearing a 3-oxa-8-azabicyclo[3.2.1]octane were prepared and evaluated for PI3-kinase/mTOR activity. Replacement of one of the bis-morpholines in lead compound 1 (PKI-587) with 3-oxa-8-azabicyclo[3.2.1]octane and reduction of the molecular weight yielded 8m (PKI-179), an orally efficacious dual PI3-kinase/mTOR inhibitor. The in vitro activity, in vivo efficacy, and PK properties of 8m are discussed.

Anti-hepatitis C virus (HCV) drug development has been challenged by a lack of experience with inhibitors inclusive of in vitro, animal model, and clinical study. This manuscript outlines activity and correlation across such a spectrum of models and into clinical trials with a novel selective nonstructural protein 5B (NS5B) polymerase inhibitor, HCV796. Enzyme assays yielded median inhibitory concentration (IC50) values of 0.01 to 0.14 μM for genotype 1, with half maximal effective concentration (EC50s) of 5 nM and 9 nM against genotype 1a and 1b replicons. In the chimeric mouse model, a 2.02 ± 0.55 log reduction in HCV titer was seen with monotherapy, whereas a suboptimal dose of 30 mg/kg three times per day in combination with interferon demonstrated a 2.44 log reduction (P = 0.001 versus interferon alone) Clinical outcomes in combination with pegylated interferon and ribavirin have revealed additive efficacy in treatment naive patients. Abnormal liver function test results were observed in 8% of HCV-796 patients treated for over 8 weeks, resulting in suspension of further trial activity. Conclusion: The RNA-dependent RNA polymerase inhibitor HCV796 demonstrated potent anti-HCV activity consistently through enzyme inhibition assays, subgenomic replicon, and chimeric mouse studies. Strong correlations of outcomes in the mouse model were seen with subsequent clinical trials, including a plateau in dose-related antiviral activity and additive impact from combination therapy with interferon. These outcomes demonstrate the utility of the range of in vitro and in vivo models now available for anti-HCV drug development and support the potential utility of polymerase inhibitors in future combination therapies for HCV treatment. (HEPATOLOGY 2009.)

A series of substituted 7-alkenyl 4[3-chloro-4-(1-methyl-1H-imidazol-2-ylsulfanyl)]anilino-3-quinolinecarbonitrile analogs were synthesized and evaluated as MEK1 kinase inhibitors. The synthetic details, structure–activity relationships, biological activity, and selected oral exposure studies of these analogs are described. From these studies, compound 5m was chosen as a strong candidate for further evaluation. The selectivity of 5m was ascertained against a panel of 17 kinases, where activity was observed against EGFR, Src, Lyn, and IR kinases. Western blot studies in WM-266 cells demonstrated that 5m inhibited phosphorylation of ERK, while additional kinase pathways tested showed no inhibition at up to 10 μM of 5m. PK studies, as well as a xenograft and in vivo biomarker studies are described for 5m.

Phosphoinositide 3-kinase (PI3K) is an important target for cancer chemotherapy due to the deregulation of its signaling pathway in a wide spectrum of human tumors. Wortmannin and its analogues are potent PI3K inhibitors whose therapeutic use has been impeded by inherent defects such as instability and toxicity. Pegylation of wortmannin and 17-hydroxywortmannin gives rise to conjugates with improved properties, including a higher therapeutic index. Pegylated 17-hydroxywortmannin (8, PWT-458) has been selected for further development.

The Raf-MEK-ERK signaling pathway is critical for cell survival, growth, proliferation and tumorigenesis. The RAF kinases, ARAF, BRAF and CRAF, are essential signaling serine-threonine kinase proteins in the cascade. B-Raf mutations are frequent in human cancers suggesting small molecule B-Raf kinase inhibitors represent potential therapeutics for treatment of various cancers. The tolerability and limited safety of WYE-130600, a potent and highly selective inhibitor of B-Raf, was evaluated in investigative preclinical studies in dogs and rats. In dogs, a single dose of 10 mg/kg or 4 daily doses of 1 or 3 mg/kg WYE-130600 were administered orally, followed by a 7 day drug-free observation period after the last dose at 1 mg/kg. Clinical observations, body weight, food consumption, plasma concentrations, and clinical pathology were assessed at each dosage; limited microscopic examinations were conducted at 1 and 3 mg/kg. Dose-related dermal effects were observed at all dosages and progressed in severity; described as red discoloration (flushing) of the entire body, followed by swelling and subsequent dryness and desquamation of the dermis of the ears, eyelids, muzzle, prepuce, and anus. Alterations in clinical pathology parameters (increased neutrophils, monocytes and fibrinogen) consistent with an inflammatory response were observed. Microscopic cutaneous changes correlating to the clinical WYE-130600-related dermal effects included epidermal and hair follicle hyperplasia, hyperkeratosis, squamous metaplasia of the sebaceous glands, mixed cell inflammation and prominent dermal vessels in the haired skin. Partial recovery was evident at 1 mg/kg at the end of the 7-day observation period, when microscopic changes were limited to epithelial hyperplasia and mixed cell inflammation in the skin. In rats, WYE-130600 was administered orally at dosages of 15, 50 and 150 mg/kg, once daily for 4 days, followed by a 5-day observation period after the last dose. Evaluations for compound-related effects were based on clinical observations, body weight, food consumption and limited microscopic examinations. Clinical dermal effects at ≥50 mg/kg were limited to the skin of the feet. At 150 mg/kg, red discoloration of the skin of the feet progressed, as was noted in the dog, to swelling and a dry, scaly appearance. At 50 mg/kg, only dry, scaly skin of the feet were noted. Microscopically, epithelial hyperplasia and hyperkeratosis with mixed cell inflammation of the foot pads correlated with the clinical presentation. Atrophy of the hair follicles of the skin and inflammation/ hyperplasia of the nonglandular stomach were also noted at 150 mg/kg. In summary, epithelial hyperplasia occurred in rats and dogs and was attributed to this selective B-Raf inhibitor. The commonality of this lesion in both species suggests a potential for similar effects in humans. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1677.