Fragment-Based Discovery of Allosteric Inhibitors of SH2 Domain-Containing Protein Tyrosine Phosphatase-2 (SHP2)

The ubiquitously expressed protein tyrosine phosphatase SHP2 is required for signaling downstream of receptor tyrosine kinases (RTKs) and plays a role in regulating many cellular processes. Genetic knockdown and pharmacological inhibition of SHP2 suppresses RAS/MAPK signaling and inhibit the proliferation of RTK-driven cancer cell lines. Here, we describe the first reported fragment-to-lead campaign against SHP2, where X-ray crystallography and biophysical techniques were used to identify fragments binding to multiple sites on SHP2. Structure-guided optimization, including several computational methods, led to the discovery of two structurally distinct series of SHP2 inhibitors binding to the previously reported allosteric tunnel binding site (Tunnel Site). One of these series was advanced to a low-nanomolar lead that inhibited tumor growth when dosed orally to mice bearing HCC827 xenografts. Furthermore, a third series of SHP2 inhibitors was discovered binding to a previously unreported site, lying at the interface of the C-terminal SH2 and catalytic domains.

Abstract 3365: Transcriptomics-based stratification of response to MAPK inhibition in vitro better predicts sensitivity to single agent and combination treatment than MAPK genomic alteration status alone

Overactivation of mitogen-activated protein kinase (MAPK) signaling is a frequently observed driver of many cancers. Targeted MAPK pathway inhibitors have been approved as therapies in patient populations with genomic alterations to MAPK pathway genes (e.g. dabrafenib in BRAF-mutant melanoma), with multiple other MAPK-targeted therapies in development. We have previously demonstrated that cell lines with MAPK pathway genomic alterations show increased sensitivity to ASTX029, our potent and selective dual-mechanism ERK inhibitor which is currently undergoing clinical development. However, MAPK oncogene status alone is not a universal indicator of sensitivity, nor is it clear that genomic markers of sensitivity to single agent inhibition represent the optimal approach to predicting response to MAPK targeted agents in the combination setting (e.g. sotorasib + trametinib). We therefore analysed MAPK pathway related transcriptional signatures to assess predictability for response to ASTX029 in combination with a SHP2 inhibitor.

We previously presented data from large-scale viability screens assessing the response to ASTX029 as a single agent treatment (437 cell lines), as well as in combination with an inhibitor of SHP2 (491 cell lines), an upstream adaptor protein in the MAPK pathway. Using these data, several published transcriptional signatures related to the MAPK pathway were assessed for their ability to stratify sensitive vs resistant cell lines when benchmarked against MAPK oncogene genomic status alone.

All assessed transcriptomics-based scores had a significant positive correlation with growth inhibition for ERK inhibitor single agent treatment as well as in combination with a SHP2 inhibitor. Transcriptomics-based scores were shown to be more sensitive than the use of mutant MAPK oncogene status alone based on assessment of binomial regression models. The significant increase in sensitivity enables the identification of additional cell lines responsive to MAPK pathway inhibition. The sensitivity was further increased when considering response to the combination of an ERK and SHP2 inhibitor compared to the ERK inhibitor as a single agent.

This analysis demonstrates the potential use of MAPK pathway-related transcriptomics-based scores for the stratification of MAPK pathway inhibitor response. ASTX029 is currently undergoing clinical development in advanced solid tumours (NCT03520075) and transcriptomics-based methods may provide utility in refining patient selection in the clinic for single agent or combination approaches.

Citation Format: Jessica Brothwood, Andrea Biondo, Kim-Hien Dao, Keisha Hearn, Chris Hindley, Navrohit Kandola, Harold Keer, John Lyons, Yoko Nakatsuru, Marc O'Reilly, Nicola Wallis, Harpreet Saini. Transcriptomics-based stratification of response to MAPK inhibition in vitro better predicts sensitivity to single agent and combination treatment than MAPK genomic alteration status alone [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3365.

Abstract 1661: Immune modulation by the dual-mechanism ERK inhibitor, ASTX029, in MAPK-activated tumor models

Whilst mitogen-activated protein kinase (MAPK) pathway inhibitors are approved therapies in mutant-BRAF driven cancers and have demonstrated a high response rate in the clinic, the duration of response is often short-lived. Approaches targeting the immune system have elicited durable responses and led to the approval of checkpoint inhibitors such as the anti-PD1 therapy, pembrolizumab, in indications where MAPK pathway activation is often observed, such as melanoma. Activation of the MAPK pathway has been associated with an immunosuppressive tumor microenvironment (TME). Further, preclinical studies have demonstrated that in addition to inhibiting MAPK activity in tumor cells, MAPK pathway inhibitors such as the BRAFV600E inhibitor dabrafenib or MEK inhibitor trametinib have promoted a more proinflammatory TME leading to upregulated antigen presentation on tumor cells, increased CD8+ T cell infiltration and tumor cell killing. Similar preclinical results were recently reported for a KRASG12C inhibitor, AMG 510, where treatment of in vivo models led to an increase in tumor infiltrating lymphocytes, macrophages, dendritic cells and an increase in active immune gene signatures leading to tumor immunity. We have recently described the discovery of ASTX029, which is currently undergoing clinical development in advanced solid tumors (NCT03520075). ASTX029 is a dual-mechanism ERK1/2 (ERK) inhibitor, inhibiting both the catalytic activity and phosphorylation of ERK, and shows potent inhibition of MAPK-activated tumor growth in preclinical models. Previous studies have demonstrated a difference in regulation of genes involved in response to type I interferon following treatment with dual-mechanism compared to catalytic ERK inhibitors. We investigated whether treatment with ASTX029 modulates antigen presentation and the TME in MAPK-activated tumors. Following treatment of cell lines in vitro, we observed ASTX029-dependent changes consistent with increased antigen presentation, including an increase in cell surface expression of MHC class I and the increase in gene expression of tumor-specific antigens gp100 and MART-1 following treatment of melanoma cells. We have previously demonstrated that ASTX029 has good bioavailability following oral dosing in mice. To further investigate the effect of ASTX029 on the TME, syngeneic tumors grown in immunocompetent mice dosed with ASTX029 were characterized in terms of immune cell composition of the TME and gene expression. Our results were consistent with increased immune activation, including increased interferon signaling and a change in the immune cell composition of the TME. These data demonstrate that treatment with ASTX029 leads to modulation of the TME and we hypothesize that to optimize therapeutic activity, ASTX029 could be partnered either with an immunomodulatory or tumor-directed agent.

Citation Format: Chris Hindley, Andrea Biondo, Kim-Hien Dao, Matthew Davis, Lynsey Fazal, Roberta Ferraldeschi, Keisha Hearn, Vanessa Martins, Harpreet Saini, Martin Sims, Nicola Wallis, Nicola Wilsher, Harold Keer, John Lyons, Joanne Munck. Immune modulation by the dual-mechanism ERK inhibitor, ASTX029, in MAPK-activated tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1661.

Structure-Based Design of Potent and Orally Active Isoindolinone Inhibitors of MDM2-p53 Protein-Protein Interaction

Inhibition of murine double minute 2 (MDM2)-p53 protein-protein interaction with small molecules has been shown to reactivate p53 and inhibit tumor growth. Here, we describe rational, structure-guided, design of novel isoindolinone-based MDM2 inhibitors. MDM2 X-ray crystallography, quantum mechanics ligand-based design, and metabolite identification all contributed toward the discovery of potent in vitro and in vivo inhibitors of the MDM2-p53 interaction with representative compounds inducing cytostasis in an SJSA-1 osteosarcoma xenograft model following once-daily oral administration.

Abstract 1039: Fragment-based drug discovery to identify small molecule allosteric inhibitors of SHP2

The ubiquitously expressed protein tyrosine phosphatase SHP2 is required for signalling downstream of receptor tyrosine kinases (RTKs) and plays a role in regulating many cellular processes. Recent advances have shown that genetic knockdown and pharmacological inhibition of SHP2 suppresses RAS/MAPK signalling and inhibits proliferation of RTK-driven cancer cell lines. SHP2 is now understood to act upstream of RAS and plays a role in KRAS-driven cancers, an area of research which is rapidly growing. Considering that RTK deregulation often leads to a wide range of cancers and the newly appreciated role of SHP2 in KRAS-driven cancers, SHP2 inhibitors are therefore a promising therapeutic approach.

SHP2 contains two N-terminal tandem SH2 domains (N-SH2, C-SH2), a catalytic phosphatase domain and a C-terminal tail. SHP2 switches between “open” active and “closed” inactive forms due to autoinhibitory interactions between the N-SH2 domain and the phosphatase domain. Historically, phosphatases were deemed undruggable as there had been no advancements with active site inhibitors. We hypothesised that fragment screening would be highly applicable and amenable to this target to enable alternative means of inhibition through identification of allosteric binding sites. Here we describe the first reported fragment screen against SHP2.

Using our fragment-based PyramidTM approach, screening was carried out on two constructs of SHP2; a closed autoinhibited C-terminal truncated form (phosphatase and both SH2 domains), as well as the phosphatase-only domain. A combination of screening methods such as X-ray crystallography and NMR were employed to identify fragment hits at multiple sites on SHP2, including the tunnel-like allosteric site reported by Chen et al, 2016. Initial fragment hits had affinities for SHP2 in the range of 1mM as measured by ITC. Binding of these hits was improved using structure-guided design to generate compounds which inhibit SHP2 phosphatase activity and are promising starting points for further optimization.

Citation Format: Philip J. Day, Valerio Berdini, Juan Castro, Gianni Chessari, Thomas G. Davies, James E. Day, Satoshi Fukaya, Chris Hamlett, Keisha Hearn, Steve Hiscock, Rhian Holvey, Satoru Ito, Yasuo Kodama, Kenichi Matsuo, Yoko Nakatsuru, Nick Palmer, Amanda Price, Tadashi Shimamura, Jeffrey D.St. Denis, Nicola G. Wallis, Glyn Williams, Christopher N. Johnson. Fragment-based drug discovery to identify small molecule allosteric inhibitors of SHP2 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1039.

Abstract 1652: Development of a potent class of small molecule inhibitors of the MDM2-p53 protein-protein interaction

In response to cellular stress, the p53 tumor suppressor is activated to modulate cell cycle progression, DNA repair, and cell death. The activity of p53 is tightly regulated by MDM2, an E3 ubiquitin ligase that targets p53 for proteasomal degradation. Inhibition of the MDM2-p53 interaction in tumors carrying wild-type p53 can therefore reactivate p53 and elicit an anti-cancer effect. Small molecule inhibitors of the MDM2-p53 interaction remains a promising strategy for cancer therapy and a number of these compounds are in clinical development.

An isoindolinone series, identified by the Northern Institute for Cancer Research (NICR), has been used as a starting point for the development of potent MDM2-p53 inhibitors. Structure based drug design was applied during lead optimisation to gain potency whilst also focusing on stabilizing the main metabolically labile position and reducing lipophilicity. This approach led to potent compounds with EC50 <1 nM against MDM2 in cell-free ELISA assays and EC50 <30 nM for p53 induction in SJSA-1 osteosarcoma cells. Further analyses of the compounds demonstrated an increase in the levels of p53 and p53 transcriptional targets as a result of inhibiting the MDM2-p53 interaction. Using three pairs of isogenic cell lines, the compounds were shown to be specific for cell lines with wild-type p53. Key compounds were also characterized in pharmacokinetic and pharmacodynamic studies in mice bearing the SJSA-1 tumor xenograft where they displayed strong induction of p53, 3 hours post oral administration, together with an increase in the expression of p53 target genes p21 and MDM2. These potent MDM2-p53 inhibitors have also shown significant in vivo efficacy in the SJSA-1 xenograft model at well tolerated oral doses. Thus, promising lead compounds were identified, meriting further optimization of the series.

Citation Format: Lynsey Fazal, Maria Ahn, Luke Bevan, Ildiko Buck, Juan Castro, Gianni Chessari, Ben Cons, Keisha Hearn, Steven Howard, Chris Johnson, Judith Reeks, Emiliano Tamanini, Neil Thompson, Hugh Walton, Pamela Williams, Ruth H. Bawn, Tim J. Blackburn, Celine Cano, Sarah J. Cully, Bernard Golding, Roger Griffin, Karen Haggerty, Ian Hardcastle, Herbie Newell, Martin Noble, Huw Thomas, Elaine Willmore, Yan Zhao, Steve Wedge. Development of a potent class of small molecule inhibitors of the MDM2-p53 protein-protein interaction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1652.

Abstract 2688: The HSP90 inhibitor, onalespib (AT13387), delays the emergence of resistance to erlotinib in an EGFR-driven xenograft model

Background: Kinase inhibitors have been used successfully in the clinic, but relapse is common due to the emergence of resistance. Inhibition of HSP90 leads to the depletion of oncogenic ‘client’ proteins and the simultaneous inhibition of many signalling pathways. As such, the use of HSP90 inhibitors to overcome resistance has been widely investigated. Onalespib (AT13387) is a potent, second generation HSP90 inhibitor, which has been studied in many preclinical models of kinase inhibitor resistance. Recent findings indicate that an upfront combination of onalespib and either vemurafenib or crizotinib, in models of mutant BRAF melanoma or ALK-translocated non-small cell lung cancer (NSCLC), can delay the emergence of resistance to these therapies. Here we have extended this work to a combination of onalespib and erlotinib in an EGFR-driven NSCLC model.

Methods: Mice bearing HCC827 tumor xenografts were dosed with either 12.5 mg/kg erlotinib po qd, or a combination of 12.5 mg/kg erlotinib and 55 mg/kg onalespib ip qw for 52 weeks.

Results: Initially both the erlotinib single-agent and onalespib/erlotinib combination treatments significantly inhibited tumor growth of the EGFR-driven NSCLC HCC827 xenograft model; all tumors in the monotherapy and combination groups regressed rapidly and achieved complete response (CR) (median times to CR were 79 and 56 days for monotherapy and combination treatments respectively). However, after 20 weeks of continuous treatment, tumor relapse was observed in one of the xenografts dosed with erlotinib only and this was followed by regrowth of a further 2 tumors in this group over the 52-week study period, with these tumors reaching 50% of the original tumor volumes by 26 and 46 weeks. Of the remaining tumors, 5 out of 6 were detectable at the end of the study. In comparison, tumor growth remained inhibited in the group treated with the erlotinib/onalespib combination; no tumors were observed to regrow over the course of the study and none (of 9) were palpable when treatments were terminated. This suggests that while treatment with monotherapy erlotinib in this model leads to relapse, as seen in the clinic, combination treatment with onalespib can delay the emergence of resistance.

Conclusions: These data demonstrate that an upfront combination of onalespib and erlotinib can delay the emergence of resistance in an EGFR-driven xenograft model, suggesting there is therapeutic potential for an upfront erlotinib/onalespib combination in the clinic. Onalespib is currently being tested in a Phase 2 clinical trial in combination with crizotinib in ALK-positive NSCLC. The preclinical data presented here, alongside our previous data on combinations of onalespib with vemurafenib or crizotinib, suggest that the concept of using an HSP90 inhibitor combination upfront in the clinic to delay resistance could be extended to further targeted therapies.

Citation Format: Aurélie Courtin, Tomoko Smyth, Keisha Hearn, John Lyons, Neil Thompson, Nicola G. Wallis. The HSP90 inhibitor, onalespib (AT13387), delays the emergence of resistance to erlotinib in an EGFR-driven xenograft model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2688. doi:10.1158/1538-7445.AM2015-2688

Fragment-Based Discovery of Potent and Selective DDR1/2 Inhibitors

The DDR1 and DDR2 receptor tyrosine kinases are activated by extracellular collagen and have been implicated in a number of human diseases including cancer. We performed a fragment-based screen against DDR1 and identified fragments that bound either at the hinge or in the back pocket associated with the DFG-out conformation of the kinase. Modeling based on crystal structures of potent kinase inhibitors facilitated the "back-to-front" design of potent DDR1/2 inhibitors that incorporated one of the DFG-out fragments. Further optimization led to low nanomolar, orally bioavailable inhibitors that were selective for DDR1 and DDR2. The inhibitors were shown to potently inhibit DDR2 activity in cells but in contrast to unselective inhibitors such as dasatinib, they did not inhibit proliferation of mutant DDR2 lung SCC cell lines.

Inhibition of HSP90 by AT13387 delays the emergence of resistance to BRAF inhibitors and overcomes resistance to dual BRAF and MEK inhibition in melanoma models

Emergence of clinical resistance to BRAF inhibitors, alone or in combination with MEK inhibitors, limits clinical responses in melanoma. Inhibiting HSP90 offers an approach to simultaneously interfere with multiple resistance mechanisms. Using the HSP90 inhibitor AT13387, which is currently in clinical trials, we investigated the potential of HSP90 inhibition to overcome or delay the emergence of resistance to these kinase inhibitors in melanoma models. In vitro, treating vemurafenib-sensitive cells (A375 or SK-MEL-28) with a combination of AT13387 and vemurafenib prevented colony growth under conditions in which vemurafenib treatment alone generated resistant colonies. In vivo, when AT13387 was combined with vemurafenib in a SK-MEL-28, vemurafenib-sensitive model, no regrowth of tumors was observed over 5 months, although 2 of 7 tumors in the vemurafenib monotherapy group relapsed in this time. Together, these data suggest that the combination of these agents can delay the emergence of resistance. Cell lines with acquired vemurafenib resistance, derived from these models (A375R and SK-MEL-28R) were also sensitive to HSP90 inhibitor treatment; key clients were depleted, apoptosis was induced, and growth in 3D culture was inhibited. Similar effects were observed in cell lines with acquired resistance to both BRAF and MEK inhibitors (SK-MEL-28RR, WM164RR, and 1205LuRR). These data suggest that treatment with an HSP90 inhibitor, such as AT13387, is a potential approach for combating resistance to BRAF and MEK inhibition in melanoma. Moreover, frontline combination of these agents with an HSP90 inhibitor could delay the emergence of resistance, providing a strong rationale for clinical investigation of such combinations in BRAF-mutated melanoma.

Abstract A55: Potent, dual cIAP1/XIAP antagonists induce apoptosis in a melanoma stem cell population

The inhibitor of apoptosis proteins (IAP) are key regulators of anti-apoptotic and pro-survival signaling pathways. Overexpression of IAPs occurs in various cancers and has been associated with tumor progression and resistance to treatment. IAP antagonists activate the E3 ligase function of cIAP1 and stimulate rapid autoubiquitylation and proteosomal degradation of both cIAP1 and cIAP2. Elimination of these proteins leads to a switch in TNFα signalling from being pro-survival to being pro-apoptotic. However, a strong pro-apoptotic effect from cIAP loss cannot be achieved without sustained antagonism of XIAP-mediated caspase inhibition. Therefore, a best in class profile for IAP antagonists requires potent dual antagonism of cIAP1 and XIAP. Astex has used fragment based-drug discovery to develop a second generation of IAP antagonists, which are non-peptidomimetic and do not contain an alanine as a warhead. This series has the ability not only to efficiently degrade cIAP1 but also to potently antagonize XIAP, delivering a dual cIAP1/XIAP inhibitory profile which is not apparent in the first generation of IAP antagonists based on an alanine warhead. Here, we report the structural understanding of the unique molecular profile of the series together with the enhanced activity of these compounds in melanoma cancer stem cells (CSC). CSC populations are more resistant to apoptosis than the bulk cell population and they have been associated with resistance to cancer therapy, relapse and cancer progressions. Blockade of the apoptotic pathway by up-regulation of anti-apoptotic factors has been implicated in conferring resistance in CSC fractions and increased XIAP expression has also been reported in these cells. We have analysed the CD133+ population of three melanoma cell lines (SK-MEL-2, SK-MEL-5 and SK-MEL-28) and measured activation of caspase-3 (NucView™ cell staining) after treatment with IAP antagonists in presence of TNFα. Our potent dual cIAP1/XIAP antagonists (XIAP EC50 <= 5 nM in cells) have a significantly enhanced apoptosis-inducing capacity (p<0.05), on the CSC fraction in all three cell lines, compared to alanine-containing cIAP1 selective antagonists, with reduced XIAP potency (XIAP EC50 > 35 nM in cells). The enhanced XIAP potency of our compounds is overriding the resistance in CSC subpopulations, highlighting the importance of dual antagonism in promoting efficient induction of apoptosis.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A55.

Citation Format: Gianni Chessari, Maria Ahn, Keisha Hearn, Christopher N. Johnson, Jon Lewis, Neil Thompson, George Ward, Pamela Williams. Potent, dual cIAP1/XIAP antagonists induce apoptosis in a melanoma stem cell population. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A55.

Abstract 2018: Discovery of potent dual inhibitors of both XIAP and cIAP1 using fragment based drug discovery

XIAP and cIAP1 are members of the inhibitor of apoptosis (IAP) protein family. Both proteins have the ability to attenuate apoptosis induced through intrinsic and extrinsic stimuli via inhibition of caspase-3, -7, -8 and -9. The defining feature of both XIAP and cIAP1 is the presence in their protein sequence of 3 Baculoviral IAP Repeat (BIR) domains, which are necessary for their antiapoptotic activity. The mitochondrial protein SMAC uses its N-terminal region (AVPI) to interact with BIR domains and deactivate the antiapoptotic function of IAPs. Several companies and academic groups have active programs developing SMAC peptidomimetic compounds based on the AVPI motif. In general, those compounds have the tendency to be cIAP1 selective like their tetrapeptide progenitor (AVPI IC50 values for XIAP-BIR3 and cIAP1-BIR3 are 0.3 uM and 0.016 uM respectively). Using our fragment-based screening approach, PyramidTM, we identified a non-peptidomimetic chemotype which binds with similar potency to the BIR3 domain of both XIAP and cIAP1. Hit optimisation using a structure based approach led to the discovery of potent true dual XIAP and cIAP1 antagonists with good in vivo physico-chemical profile and no P450 or hERG liabilities. Dual XIAP/cIAP1 inhibitors have potential for more effective apoptosis and less toxicity associated with cytokine production. Compounds were initially characterised in fluorescence polarisation binding assays using XIAP-BIR3 or cIAP1-BIR3 domains. Robust induction of apoptosis was observed in two sensitive breast cancer cell lines (EC50s well below 0.1 uM in EVSA-T and MDA-MB-231); whilst HCT116 cells (colon cancer) were insensitive (unless exogenous TNF-α was added). This in vitro cell line killing was demonstrated to correlate closely with cIAP1 antagonism and hence a parallel cell assay was established to measure XIAP antagonism. An engineered HEK293 cell line was stably co-transfected with full length FLAG-tagged human XIAP cDNA and full length (untagged) human caspase-9 cDNA. Inhibition of caspase-9 binding to XIAP was measured in immunoprecipitation assays. This gave us a sensitive read-out for XIAP antagonism in cells which could be plotted against the most sensitive cell killing read-out (from the EVSA-T cell line) to establish relative XIAP vs cIAP1 selectivities and to select dual antagonists of both IAPs. Potent compounds (HEK293-EC50 <0.01 uM and EVSA-T-EC50 <0.01 uM) were further characterised in PKPD studies in mice bearing MDA-MB-231 xenografts. Compounds with good oral exposure achieved high concentration in tumor over 24h periods which ensured excellent inhibition of both XIAP and cIAP1 with consequent reduction of cIAP1 levels and induction of apoptosis markers (PARP, Caspase-3). Finally, dual XIAP/cIAP1 inhibitors have been investigated in xenograft models (melanoma, breast and colorectal cancer) and have achieved significant efficacy at tolerated doses.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2018. doi:1538-7445.AM2012-2018

Reduce costs and improve patient satisfaction with home pre-operative bowel preparations

The results of a home-based preoperative bowel preparation, with and without the support of home care services, are compared with hospital-based preoperative bowel preparation. Length of stay, morbidity, and mortality rates; issues of patient satisfaction; and demographics are reported. The method and tools used in planning, implementing, and evaluating the home preoperative bowel preparation program are also shared. Other issues discussed are the healthcare market forces that promote an increased value of care. Economic and patient satisfaction considerations by employers, payers, and patients; the increasing influence of patient choice on healthcare provider selection and care setting preferences; the nursing workforce issues related to the impending shortage; and issues of regulatory and accrediting agencies are also discussed.

Working hours. Minute stakes

The working time directive has major implications for NHS employers. Many NHS employers believe current systems for recording hours worked will not meet the directive's requirements. The introduction of leave entitlement for bank and agency nurses is likely to cost the NHS an extra 40 m Pounds or more a year. The directive does not currently apply to junior doctors. But if, as expected, they are brought within it, the implications for the NHS are huge.

Critical care unit design, Part III: Establishing operations

Last-minute details are checked and rechecked as a new critical care unit moves into its final phase of development. Adequate preparation involving orientation, education, budgets and open house activities assures a smooth transition.

Angiographic, electrocardiographic and surgical features of single coronary artery producing myocardial ischaemia

A patient is described in whom an unstenosed single coronary artery was associated with angina and syncope. Full clinical documentation of the patient with ambulatory electrocardiography, angiography, surgical findings and stress testing before and after bypass grafting are described.

Aortic valve replacement with unsupported fascia lata

Hearn, K., Somerville, Jane, Sutton, R., Wright, J., and Ross, D. (1973).Thorax, 28, 603-607. Aortic valve replacement with unsupported fascia lata. Twenty-five patients in the National Heart Hospital have had aortic valve replacement with unsupported autologous fascia lata and have been followed for two to three and a half years. Three patients died before leaving hospital. Nine of the 22 survivors required re-operation for severe aortic regurgitation and the other 13 developed aortic incompetence. In 11, regurgitation dated from the operation and progressed; and in 11 it appeared later and progressed. In view of the disappointing results which were obvious within six months unsupported autologous fascia lata valves have not been used for aortic valve replacement since December 1970.