A prospective radiostereometric analysis of the stability of a metal-backed glenoid component/autograft composite in reverse shoulder arthroplasty.

Aims: Reverse total shoulder arthroplasty (rTSA) can be used in complex cases when the glenoid requires reconstruction. In this study, a baseplate with composite bone autograft and a central trabecular titanium peg was implanted, and its migration was assessed for two years postoperatively using radiostereometric analysis (RSA). Methods: A total of 14 patients who underwent a rTSA with an autograft consented to participate. Of these, 11 had a primary rTSA using humeral head autograft and three had a revision rTSA with autograft harvested from the iliac crest. The mean age of the patients was 66 years (39 to 81). Tantalum beads were implanted in the scapula around the glenoid. RSA imaging (stereographic radiographs) was undertaken immediately postoperatively and at three, six, 12, and 24 months. Analysis was completed using model-based RSA software. Outcomes were collected preoperatively and at two years postoperatively, including the Oxford Shoulder Score, the American Shoulder and Elbow Score, and a visual analogue score for pain. A Constant score was also obtained for the assessment of strength and range of motion. Results: RSA analysis showed a small increase in all translation and rotational values up to six months postoperatively, consistent with settling of the implant. The mean values plateaued by 12 months, with no evidence of further migration. In four patients, there was significant variation outside the mean, which corresponded to postoperative complications. There was a significant improvement in the clinical and patient-reported outcomes from the preoperative values to those at two years postoperatively (p < 0.001). Conclusion: These findings show, using RSA, that a glenoid baseplate composite of a trabecular titanium peg with autograft stabilizes within the glenoid about 12 months after surgery, and reinforce findings from a previous study of this implant/graft with CT scans at two years postoperatively, indicating that this type of structural composite results in sound early fixation.

Survivorship of Allologous Structural Bone Graft at a Minimum of 2 Years When Used to Address Significant Glenoid Bone Loss in Revision Shoulder Arthroplasty: A Computed Tomographic and Clinical Review.

Background: This study assesses outcomes in revision shoulder replacements where the glenoid bone loss was managed using a structural allograft (donated femoral head) in combination with a trabecular titanium (TT) implant. Methods: We contacted patients who had undergone revision shoulder arthroplasty using the Lima Axioma TT metal-backed glenoid with an allologous bone graft as a composite who were over 2 years since surgery. Patients underwent computerd tomography evaluation, clinical review, and scoring preoperatively, at 6 months and the latest follow-up. Results: Fifteen patients were included with a mean age of 59 (33-76). The average follow-up period was 40.5 months (24-51). 80% showed satisfactory bone graft incorporation and peg integration at the latest follow-up. Three had signs of significant bone graft resorption, although in 2 patients the pegs were still soundly fixed in the host bone. Clinically all patients showed a statistically significant improvement in pain relief, movement, and function. No unusual complications were reported. Conclusion: Results show femoral head structural allograft in combination with TT metal-backed glenoid baseplate is a viable option for revision total shoulder replacement in the context of massive glenoid bone loss. We do, however, acknowledge that this resorption rate is higher than in other reported series where autograft is used.

Community Engagement and Data Disclosure in Environmental Health Research.

Federal funding agencies increasingly support stakeholder participation in environmental health studies, and yet there is very little published research on engagement of community members in the development of data disclosure (DD) strategies. The Ohio Environmental Protection Agency reported airborne manganese (Mn) concentrations in East Liverpool, Ohio, 30 times higher than the reference concentration, which led to an academic­community research partnership to address community concern about Mn exposure, particularly among children. Children and their families were recruited to participate in a pilot study. Samples of blood and hair were collected from the children and analyzed for metals. DD mechanisms were developed using an iterative approach between community and academic partners. Individual DD letters were mailed to each participating family, and a community meeting was held. A post-meeting survey was administered to gauge community perception of the DD strategies. The purpose of this article is to demonstrate the effectiveness of engaging community partners in the conduct of environmental health research and in the development of DD strategies for individuals and the community at large. Scientists should include community partners in the development of DD strategies to enhance translation of the research findings and support the right of study participants to know their individual results.

The clinical development candidate CCT245737 is an orally active CHK1 inhibitor with preclinical activity in RAS mutant NSCLC and Eµ-MYC driven B-cell lymphoma.

CCT245737 is the first orally active, clinical development candidate CHK1 inhibitor to be described. The IC50 was 1.4 nM against CHK1 enzyme and it exhibited>1,000-fold selectivity against CHK2 and CDK1. CCT245737 potently inhibited cellular CHK1 activity (IC50 30-220 nM) and enhanced gemcitabine and SN38 cytotoxicity in multiple human tumor cell lines and human tumor xenograft models. Mouse oral bioavailability was complete (100%) with extensive tumor exposure. Genotoxic-induced CHK1 activity (pS296 CHK1) and cell cycle arrest (pY15 CDK1) were inhibited both in vitro and in human tumor xenografts by CCT245737, causing increased DNA damage and apoptosis. Uniquely, we show CCT245737 enhanced gemcitabine antitumor activity to a greater degree than for higher doses of either agent alone, without increasing toxicity, indicating a true therapeutic advantage for this combination. Furthermore, development of a novel ELISA assay for pS296 CHK1 autophosphorylation, allowed the quantitative measurement of target inhibition in a RAS mutant human tumor xenograft of NSCLC at efficacious doses of CCT245737. Finally, CCT245737 also showed significant single-agent activity against a MYC-driven mouse model of B-cell lymphoma. In conclusion, CCT245737 is a new CHK1 inhibitor clinical development candidate scheduled for a first in man Phase I clinical trial, that will use the novel pS296 CHK1 ELISA to monitor target inhibition.

Reinterpretation of O'Brien test in posterior labral tears of the shoulder.

BACKGROUND: Injuries to the posterior labrum are less common and more difficult to diagnose compared to anterior labral pathology. This may be in part due to difficulties in preoperative diagnosis. Posterior labral injuries cause abnormal loading of the rotator cuff with subsequent weakness. Examination using the O'Briens test tightens the posterior capsule and posteriorly translates the humeral head, stressing the labrum resulting in pain and weakness. METHOD: A retrospective study. RESULTS: Of 74 patients diagnosed with a posterior labral tear at arthroscopy 55 had subjective weakness on performing a O'Briens test, a sensitivity of 83% and a positive predictive value (PPV) of 90%. CONCLUSION: Multiple tests have been described for posterior labral pathology and none of these, on their own, have a high sensitivity rate. Posterior labral injuries can often be missed on magnetic resonance imaging scanning and also at surgery if not specifically looked for. Using a sign of clinically demonstrated weakness when performing the O'Briens test, and hence reinterpretation of the test, is sensitive, with a high PPV for posterior labral pathology and can help guide further treatment.

Rehabilitation following rotator cuff repair: a systematic review.

BACKGROUND: The aim of this systematic review was to evaluate the effectiveness of rehabilitation programmes following surgical repair of the rotator cuff with emphasis upon length of immobilisation and timing of introduction of load. METHODS: An electronic search of CENTRAL, MEDLINE and PEDro was undertaken to August 2014 and supplemented by hand searching. Randomised controlled trials were included, quality appraised using the PEDro scale and synthesised via meta-analysis or narrative synthesis, based upon levels of evidence, where appropriate. RESULTS: Twelve studies were included. There is strong evidence that early initiation of rehabilitation does not adversely affect clinical outcome but there is a marginally higher, statistically non-significant, incidence of tendon re-tear (OR 1.3; 95% CI 0.72 to 2.2). There is strong evidence that initiation of functional loading early in the rehabilitation programme does not adversely affect clinical outcome. DISCUSSION: Concern about early initiation of rehabilitation and introduction of gradual functional load does not appear warranted but this should be considered in a context of potential for Type II error. There is further need to evaluate approaches that foster early initiation of rehabilitation and gradual introduction of functional load as well as considering key outcomes such as return to work.

Selective blubber fatty acid mobilization in lactating gray seals (Halichoerus grypus).

During negative energy balance periods, fatty acids (FAs) are mobilized to cover the metabolic demands of the body. FAs from adipose tissue are selectively mobilized according to their carbon length (CL) and number of double bonds (DBs); however, studies in vivo have focused only on fasting and nonlactating animals. During lactation, UK gray seals fast for 18 d, mobilizing a large amount of lipid from blubber to sustain their own metabolic demands and the nutritional requirements of pups. We investigated FA mobilization in individual gray seal mothers from two UK colonies sampled in 2005 and 2006. Linear mixed-effects models were used to examine to what extent the mobilization observed from FAs in blubber can be explained as a function of FAs' CL and number of DBs. FAs were mobilized according to their structure, such that for a given CL, mobilization increased with the number of DBs, and for a given number of DBs, mobilization decreased as CL increased. This pattern of selective mobilization was very similar between colonies, although the relative amounts of component FAs in blubber at early lactation were different between them. FAs, which are considered crucial to pup development, were mobilized more than predicted by the model. This suggests that selective mobilization of FAs is not related solely to the physicochemical characteristics of the FAs but also to the needs of a growing pup.

CCT244747 is a novel potent and selective CHK1 inhibitor with oral efficacy alone and in combination with genotoxic anticancer drugs.

PURPOSE: Many tumors exhibit defective cell-cycle checkpoint control and increased replicative stress. CHK1 is critically involved in the DNA damage response and maintenance of replication fork stability. We have therefore discovered a novel potent, highly selective, orally active ATP-competitive CHK1 inhibitor, CCT244747, and present its preclinical pharmacology and therapeutic activity. EXPERIMENTAL DESIGN: Cellular CHK1 activity was assessed using an ELISA assay, and cytotoxicity a SRB assay. Biomarker modulation was measured using immunoblotting, and cell-cycle effects by flow cytometry analysis. Single-agent oral CCT244747 antitumor activity was evaluated in a MYCN-driven transgenic mouse model of neuroblastoma by MRI and in genotoxic combinations in human tumor xenografts by growth delay. RESULTS: CCT244747 inhibited cellular CHK1 activity (IC(50) 29-170 nmol/L), significantly enhanced the cytotoxicity of several anticancer drugs, and abrogated drug-induced S and G(2) arrest in multiple tumor cell lines. Biomarkers of CHK1 (pS296 CHK1) activity and cell-cycle inactivity (pY15 CDK1) were induced by genotoxics and inhibited by CCT244747 both in vitro and in vivo, producing enhanced DNA damage and apoptosis. Active tumor concentrations of CCT244747 were obtained following oral administration. The antitumor activity of both gemcitabine and irinotecan were significantly enhanced by CCT244747 in several human tumor xenografts, giving concomitant biomarker modulation indicative of CHK1 inhibition. CCT244747 also showed marked antitumor activity as a single agent in a MYCN-driven neuroblastoma. CONCLUSION: CCT244747 represents the first structural disclosure of a highly selective, orally active CHK1 inhibitor and warrants further evaluation alone or combined with genotoxic anticancer therapies.

AT13148 is a novel, oral multi-AGC kinase inhibitor with potent pharmacodynamic and antitumor activity.

PURPOSE: Deregulated phosphatidylinositol 3-kinase pathway signaling through AGC kinases including AKT, p70S6 kinase, PKA, SGK and Rho kinase is a key driver of multiple cancers. The simultaneous inhibition of multiple AGC kinases may increase antitumor activity and minimize clinical resistance compared with a single pathway component. EXPERIMENTAL DESIGN: We investigated the detailed pharmacology and antitumor activity of the novel clinical drug candidate AT13148, an oral ATP-competitive multi-AGC kinase inhibitor. Gene expression microarray studies were undertaken to characterize the molecular mechanisms of action of AT13148. RESULTS: AT13148 caused substantial blockade of AKT, p70S6K, PKA, ROCK, and SGK substrate phosphorylation and induced apoptosis in a concentration and time-dependent manner in cancer cells with clinically relevant genetic defects in vitro and in vivo. Antitumor efficacy in HER2-positive, PIK3CA-mutant BT474 breast, PTEN-deficient PC3 human prostate cancer, and PTEN-deficient MES-SA uterine tumor xenografts was shown. We show for the first time that induction of AKT phosphorylation at serine 473 by AT13148, as reported for other ATP-competitive inhibitors of AKT, is not a therapeutically relevant reactivation step. Gene expression studies showed that AT13148 has a predominant effect on apoptosis genes, whereas the selective AKT inhibitor CCT128930 modulates cell-cycle genes. Induction of upstream regulators including IRS2 and PIK3IP1 as a result of compensatory feedback loops was observed. CONCLUSIONS: The clinical candidate AT13148 is a novel oral multi-AGC kinase inhibitor with potent pharmacodynamic and antitumor activity, which shows a distinct mechanism of action from other AKT inhibitors. AT13148 will now be assessed in a first-in-human phase I trial.

A Phase II trial of 17-allylamino, 17-demethoxygeldanamycin (17-AAG, tanespimycin) in patients with metastatic melanoma.

PURPOSE: A Phase II study to screen for anti-melanoma activity of the heat shock protein 90 (HSP90) inhibitor, 17-AAG (17-allylamino-17-demethoxygeldanamycin) was performed. The primary endpoint was the rate of disease stabilisation in patients with progressive, metastatic melanoma treated with 17-AAG. Secondary endpoints were to determine: the toxicity of 17-AAG, the duration of response(s), median survival and further study the pharmacokinetics and pharmacodynamics of 17-AAG. PATIENTS AND METHODS: Patients with metastatic melanoma (progressive disease documented ≤6 months of entering study) were treated with weekly, intravenous 17-AAG. A Simon one sample two stage minimax design was used. A stable disease rate of ≥25% at 6 months was considered compatible with 17-AAG having activity. RESULTS: Fourteen patients (8 male: 6 female) were entered, eleven received 17-AAG (performance status 0 or 1). Median age was 60 (range 29-81) years. The majority (93%) received prior chemotherapy and had stage M1c disease (71%). Toxicity was rarely ≥ Grade 2 in severity and commonly included fatigue, headache and gastrointestinal disturbances. One of eleven patients treated with 17-AAG had stable disease for 6 months and median survival for all patients was 173 days. The study was closed prematurely prior to completion of the first stage of recruitment and limited planned pharmacokinetic and pharmacodynamic analyses. CONCLUSION: Some evidence of 17-AAG activity was observed although early study termination meant study endpoints were not reached. Stable disease rates can be incorporated into trials screening for anti-melanoma activity and further study of HSP90 inhibitors in melanoma should be considered.

Design, synthesis and biological evaluation of 6-pyridylmethylaminopurines as CDK inhibitors.

The cyclin-dependent kinase (CDK) inhibitor seliciclib (1, CYC202) is in phase II clinical development for the treatment of cancer. Here we describe the synthesis of novel purines with greater solubility, lower metabolic clearance, and enhanced potency versus CDKs. These compounds exhibit novel selectivity profiles versus CDK isoforms. Compound αSßR-21 inhibits CDK2/cyclin E with IC(50)=30 nM, CDK7-cyclin H with IC(50)=1.3 µM, and CDK9-cyclinT with IC(50)=0.11 µM; it (CCT68127) inhibits growth of HCT116 colon cancer cells in vitro with GI(50)=0.7 µM; and shows antitumour activity when dosed p.o. at 50mg/kg to mice bearing HCT116 solid human tumour xenografts.

A phase I study of the heat shock protein 90 inhibitor alvespimycin (17-DMAG) given intravenously to patients with advanced solid tumors.

PURPOSE: A phase I study to define toxicity and recommend a phase II dose of the HSP90 inhibitor alvespimycin (17-DMAG; 17-dimethylaminoethylamino-17-demethoxygeldanamycin). Secondary endpoints included evaluation of pharmacokinetic profile, tumor response, and definition of a biologically effective dose (BED). PATIENTS AND METHODS: Patients with advanced solid cancers were treated with weekly, intravenous (i.v.) 17-DMAG. An accelerated titration dose escalation design was used. The maximum tolerated dose (MTD) was the highest dose at which ≤ 1/6 patients experienced dose limiting toxicity (DLT). Dose de-escalation from the MTD was planned with mandatory, sequential tumor biopsies to determine a BED. Pharmacokinetic and pharmacodynamic assays were validated prior to patient accrual. RESULTS: Twenty-five patients received 17-DMAG (range 2.5-106 mg/m(2)). At 106 mg/m(2) of 17-DMAG 2/4 patients experienced DLT, including one treatment-related death. No DLT occurred at 80 mg/m(2). Common adverse events were gastrointestinal, liver function changes, and ocular. Area under the curve and mean peak concentration increased proportionally with 17-DMAG doses 80 mg/m(2) or less. In peripheral blood mononuclear cells significant (P < 0.05) HSP72 induction was detected (≥ 20 mg/m(2)) and sustained for 96 hours (≥ 40 mg/m(2)). Plasma HSP72 levels were greatest in the two patients who experienced DLT. At 80 mg/m(2) client protein (CDK4, LCK) depletion was detected and tumor samples from 3 of 5 patients confirmed HSP90 inhibition. Clinical activity included complete response (castration refractory prostate cancer, CRPC 124 weeks), partial response (melanoma, 159 weeks), and stable disease (chondrosarcoma, CRPC, and renal cancer for 28, 59, and 76 weeks, respectively). CONCLUSIONS: The recommended phase II dose of 17-DMAG is 80 mg/m(2) weekly i.v.

Preclinical pharmacology, antitumor activity, and development of pharmacodynamic markers for the novel, potent AKT inhibitor CCT128930.

AKT is frequently deregulated in cancer, making it an attractive anticancer drug target. CCT128930 is a novel ATP-competitive AKT inhibitor discovered using fragment- and structure-based approaches. It is a potent, advanced lead pyrrolopyrimidine compound exhibiting selectivity for AKT over PKA, achieved by targeting a single amino acid difference. CCT128930 exhibited marked antiproliferative activity and inhibited the phosphorylation of a range of AKT substrates in multiple tumor cell lines in vitro, consistent with AKT inhibition. CCT128930 caused a G(1) arrest in PTEN-null U87MG human glioblastoma cells, consistent with AKT pathway blockade. Pharmacokinetic studies established that potentially active concentrations of CCT128930 could be achieved in human tumor xenografts. Furthermore, CCT128930 also blocked the phosphorylation of several downstream AKT biomarkers in U87MG tumor xenografts, indicating AKT inhibition in vivo. Antitumor activity was observed with CCT128930 in U87MG and HER2-positive, PIK3CA-mutant BT474 human breast cancer xenografts, consistent with its pharmacokinetic and pharmacodynamic properties. A quantitative immunofluorescence assay to measure the phosphorylation and total protein expression of the AKT substrate PRAS40 in hair follicles is presented. Significant decreases in pThr246 PRAS40 occurred in CCT128930-treated mouse whisker follicles in vivo and human hair follicles treated ex vivo, with minimal changes in total PRAS40. In conclusion, CCT128930 is a novel, selective, and potent AKT inhibitor that blocks AKT activity in vitro and in vivo and induces marked antitumor responses. We have also developed a novel biomarker assay for the inhibition of AKT in human hair follicles, which is currently being used in clinical trials.

AT7867 is a potent and oral inhibitor of AKT and p70 S6 kinase that induces pharmacodynamic changes and inhibits human tumor xenograft growth.

The serine/threonine kinase AKT plays a pivotal role in signal transduction events involved in malignant transformation and chemoresistance and is an attractive target for the development of cancer therapeutics. Fragment-based lead discovery, combined with structure-based drug design, has recently identified AT7867 as a novel and potent inhibitor of both AKT and the downstream kinase p70 S6 kinase (p70S6K) and also of protein kinase A. This ATP-competitive small molecule potently inhibits both AKT and p70S6K activity at the cellular level, as measured by inhibition of GSK3beta and S6 ribosomal protein phosphorylation, and also causes growth inhibition in a range of human cancer cell lines as a single agent. Induction of apoptosis was detected by multiple methods in tumor cells following AT7867 treatment. Administration of AT7867 (90 mg/kg p.o. or 20 mg/kg i.p.) to athymic mice implanted with the PTEN-deficient U87MG human glioblastoma xenograft model caused inhibition of phosphorylation of downstream substrates of both AKT and p70S6K and induction of apoptosis, confirming the observations made in vitro. These doses of AT7867 also resulted in inhibition of human tumor growth in PTEN-deficient xenograft models. These data suggest that the novel strategy of AKT and p70S6K blockade may have therapeutic value and supports further evaluation of AT7867 as a single-agent anticancer strategy.

Targeting the PI3K-AKT-mTOR pathway: progress, pitfalls, and promises.

The strategy of 'drugging the cancer kinome' has led to the successful development and regulatory approval of several novel molecular targeted agents. The spotlight is now shifting to the phosphatidylinositide 3-kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) pathway as a key potential target. This review details the role of the pathway in oncogenesis and the rationale for inhibiting its vital components. The focus will be on the progress made in the development of novel therapies for cancer treatment, with emphasis placed on agents that have entered clinical development. Strategies involving horizontal and vertical blockade of the pathway, as well as the use of biomarkers to select appropriate patients and to provide proof of target modulation will also be highlighted. Finally, we discuss the issues and limitations involved with targeting the PI3K-AKT-mTOR pathway, and predict what the future may hold for these novel anticancer therapeutics.

An evaluation of the ability of pifithrin-alpha and -beta to inhibit p53 function in two wild-type p53 human tumor cell lines.

The small-molecule compound pifithrin-alpha (PFT-alpha) has been reported to inhibit p53 function and protect against a variety of genotoxic agents. We show here that PFT-alpha is unstable in tissue culture medium and is rapidly converted to its condensation product PFT-beta. Both compounds showed limited solubility with PFT-alpha precipitating out of tissue culture medium at concentrations >30 micromol/L. PFT-alpha and -beta exhibited cytotoxic effects in vitro towards two human wild-type p53-expressing tumor cell lines, A2780 ovarian and HCT116 colon (IC(50) values for both cell lines were 21.3 +/- 8.1 micromol/L for PFT-alpha and 90.3 +/- 15.5 micromol/L for PFT-beta, mean +/- SD, n = 4). There was no evidence of protection by clonogenic assay with either compound in combination with ionizing radiation. Indeed, there was some evidence that PFT-alpha enhanced cytotoxicity, particularly at higher concentrations of PFT-alpha. Neither compound had any effect on p53, p21, or MDM-2 protein expression following ionizing radiation exposure and there was no evidence of any abrogation of p53-dependent, ionizing radiation-induced cell cycle arrest. Similarly, there was no evidence of cellular protection, or of effects on p53-dependent gene transcription, or on translation of MDM-2 or p21 following UV treatment of these human tumor cell lines. In addition, there was no effect on p53 or p21 gene transactivation or p38 phosphorylation after UV irradiation of NIH-3T3 mouse fibroblasts. In conclusion, neither PFT-alpha nor -beta can be regarded as a ubiquitous inhibitor of p53 function, and caution should be exercised in the use of these agents as specific p53 inhibitors.

The Cyclin-dependent kinase inhibitor CYC202 (R-roscovitine) inhibits retinoblastoma protein phosphorylation, causes loss of Cyclin D1, and activates the mitogen-activated protein kinase pathway.

Deregulation of the cell cycle commonly occurs during tumorigenesis, resulting in unrestricted cell proliferation and independence from mitogens. Cyclin-dependent kinase inhibitors have the potential to induce cell cycle arrest and apoptosis in cancer cells. CYC202 (R-roscovitine) is a potent inhibitor of CDK2/cyclin E that is undergoing clinical trials. Drugs selected to act on a particular molecular target may exert additional or alternative effects in intact cells. We therefore studied the molecular pharmacology of CYC202 in human colon cancer cells. Treatment of HT29 and KM12 colon carcinoma cell lines with CYC202 decreased both retinoblastoma protein phosphorylation and total retinoblastoma protein. In addition, an increase in the phosphorylation of extracellular signal-regulated kinases 1/2 was observed. As a result, downstream activation of the mitogen-activated protein kinase pathway occurred, as demonstrated by an increase in ELK-1 phosphorylation and in c-FOS expression. Use of mitogen-activated protein kinase kinases 1/2 inhibitors showed that the CYC202-induced extracellular signal-regulated kinases 1/2 phosphorylation was mitogen-activated protein kinase kinases 1/2 dependent but did not contribute to the cell cycle effects of the drug, which included a reduction of cells in G(1), inhibition of bromodeoxyuridine incorporation during S-phase, and a moderate increase in G(2)-M phase. Despite activation of the mitogen-activated protein kinase pathway, cyclin D1 protein levels were decreased by CYC202, an effect that occurred simultaneously with loss of retinoblastoma protein phosphorylation and inhibition of cell cycle progression. The reduced expression of cyclin D1 protein was independent of the p38(SAPK) and phosphatidylinositol 3-kinase pathways, which are known regulators of cyclin D1 protein. Interestingly, CYC202 caused a clear reduction in cyclins D1, A, and B1 mRNA, whereas c-FOS mRNA increased by 2-fold. This was accompanied by a loss of RNA polymerase II phosphorylation and total RNA polymerase II protein, suggesting that CYC202 was inhibiting transcription, possibly via inhibition of CDK7 and CDK9 complexes. It can be concluded that although CYC202 can act as a CDK2 inhibitor, it also has the potential to inhibit CDK4 and CDK1 activities in cancer cells through the down-regulation of the corresponding cyclin partners. This provides a possible mechanism by which CYC202 can cause a reduction in retinoblastoma protein phosphorylation at multiple sites and cell cycle arrest in G(1), S, and G(2)-M phases. In addition to providing useful insights into the molecular pharmacology of CYC202 in human cancer cells, the results also suggest potential pharmacodynamic end points for use in clinical trials with the drug.

Magnetic resonance spectroscopic pharmacodynamic markers of the heat shock protein 90 inhibitor 17-allylamino,17-demethoxygeldanamycin (17AAG) in human colon cancer models.

BACKGROUND: 17-allylamino,17-demethoxygeldanamycin (17AAG) is a novel anticancer drug that inhibits heat shock protein 90 (Hsp90), resulting in proteasomal degradation of several oncogenic proteins. We used phosphorus magnetic resonance spectroscopy (31P-MRS) to determine whether 17AAG treatment leads to alterations in phospholipids that could serve as pharmacodynamic markers for tumor response to 17AAG. METHODS: HCT116, HT29, and SW620 colon cancer cells were treated with 17AAG, and extracts were examined by 31P-MRS. HT29 cells were also treated with the active metabolite of 17AAG, 17-amino,17-demethoxygeldanamycin (17AG), or the inactive 17AAG analog NSC683666. MF-1 nude mice carrying HT29 xenografts were examined using in vivo 31P-MRS before and after 17AAG treatment; xenograft tumor extracts were examined by 31P-MRS and proton MRS (1H-MRS). Hsp90 client protein expression was determined by using western blots. Two-tailed t tests were used to compare metabolite concentrations and ratios, and a Mann-Whitney U test was used to compare proportions. All statistical tests were two-sided. RESULTS: 17AAG treatment led to statistically significantly increased phosphocholine levels in all three cell lines (P =.02). 17AG treatment also increased phosphocholine levels in HT29 cells, whereas NSC683666 had no effect. The phosphomonoester/phosphodiester ratio was statistically significantly increased in the HT29 xenografts after 17AAG treatment relative to the pretreatment ratio (P =.02), whereas no statistically significant change was observed after vehicle treatment (P =.62). Statistically significant increases in phosphocholine, phosphoethanolamine, and valine levels were also observed in tumor extracts treated with 17AAG. CONCLUSIONS: Inhibition of Hsp90 by 17AAG resulted in altered phospholipid metabolism in cultured tumor cells and in tumor xenografts. The increases observed in phosphocholine and phosphomonoester levels suggest that these metabolites may have the potential to act as noninvasive pharmacodynamic markers for analyzing tumor response to treatment with 17AAG or other Hsp90 inhibitors.

The contemporary drug development process: advances and challenges in preclinical and clinical development.

We are in a new era of drug discovery, in which it is feasible to develop therapeutic agents targeted at a particular protein or biological activity in a living cell. This has been made possible by major advances in our understanding of cell and molecular biology, epitomized by the 2001 Nobel prize award for Physiology or Medicine to Lee Hartwell, Tim Hunt and Paul Nurse, who were recognised for their work on key regulators of the cell cycle. Technological advances have also played a decisive role, leading to the sequencing of the human genome and increased throughput at many stages of the drug discovery and development process. For example, developments in high throughput screening, structural biology and microarray technology are increasing the speed of drug discovery. In this chapter we focus on the long, and often difficult, pathway which leads from identification of a hit in a screen to regulatory approval of a drug for disease treatment. The emphasis in this chapter is on the development of anticancer drugs, as this is our own area of expertise and also because cancer is a disease in which the cell cycle is already a major target for therapeutic intervention. However, many of the concepts, approaches and issues are generally common to other therapeutic areas.