Paul D. Smith

Bio: Paul D. Smith is an academic researcher from AstraZeneca. The author has contributed to research in topics: Selumetinib & MEK inhibitor. The author has an hindex of 53, co-authored 207 publications receiving 10843 citations. Previous affiliations of Paul D. Smith include National Institutes of Health & Institute of Cancer Research.

Selumetinib plus docetaxel for KRAS-mutant advanced non-small-cell lung cancer: a randomised, multicentre, placebo-controlled, phase 2 study

Abstract: Summary Background No targeted therapies are available for KRAS -mutant non-small-cell lung cancer (NSCLC). Selumetinib is an inhibitor of MEK1/MEK2, downstream of KRAS, with preclinical evidence of synergistic activity with docetaxel in KRAS -mutant cancers. We did a prospective, randomised, phase 2 trial to assess selumetinib plus docetaxel in previously treated patients with advanced KRAS -mutant NSCLC. Methods Eligible patients were older than 18 years of age; had histologically or cytologically confirmed stage IIIB–IV KRAS -mutant NSCLC; had failed first-line therapy for advanced NSCLC; had WHO performance status of 0–1; had not received previous therapy with either a MEK inhibitor or docetaxel; and had adequate bone marrow, renal, and liver function. Patients were randomly assigned (in a 1:1 ratio) to either oral selumetinib (75 mg twice daily in a 21 day cycle) or placebo; all patients received intravenous docetaxel (75 mg/m 2 on day 1 of a 21 day cycle). Randomisation was done with an interactive voice response system and investigators, patients, data analysts, and the trial sponsor were masked to treatment assignment. The primary endpoint was overall survival, analysed for all patients with confirmed KRAS mutations. This study is registered with ClinicalTrials.gov, number NCT00890825. Findings Between April 20, 2009, and June 30, 2010, we randomly assigned 44 patients to receive selumetinib and docetaxel (selumetinib group) and 43 to receive placebo and docetaxel (placebo group). Of these, one patient in the selumetinib group and three in the placebo group were excluded from efficacy analyses because their tumours were not confirmed to be KRAS -mutation positive. Median overall survival was 9·4 months (6·8–13·6) in the selumetinib group and 5·2 months (95% CI 3·8–non-calculable) in the placebo group (hazard ratio [HR] for death 0·80, 80% CI 0·56–1·14; one-sided p=0·21). Median progression-free survival was 5·3 months (4·6–6·4) in the selumetinib group and 2·1 months (95% CI 1·4–3·7) in the placebo group (HR for progression 0·58, 80% CI 0·42–0·79; one-sided p=0·014). 16 (37%) patients in the selumetinib group and none in the placebo group had an objective response (p vs 23 [55%] of 42 patients in the placebo group), febrile neutropenia (eight [18%] of 44 patients in the selumetinib group vs none in the placebo group), dyspnoea (one [2%] of 44 patients in the selumetinib group vs five [12%] of 42 in the placebo group), and asthenia (four [9%] of 44 patients in the selumetinib group vs none in the placebo group). Interpretation Selumetinib plus docetaxel has promising efficacy, albeit with a higher number of adverse events than with docetaxel alone, in previously treated advanced KRAS -mutant NSCLC. These findings warrant further clinical investigation of selumetinib plus docetaxel in KRAS -mutant NSCLC. Funding AstraZeneca.

Gene Expression Profiling of Alveolar Rhabdomyosarcoma with cDNA Microarrays

Abstract: Several forms of human sarcoma, lymphoma, and leukemia are characterized by somatically acquired chromosome translocations that result in fusion genes that encode chimeric transcription factors with oncogenic properties. We have used cDNA microarrays containing 1238 cDNAs to investigate the gene expression profile of a group of seven alveolar rhabdomyosarcoma (ARMS) cell lines characterized by the presence of the PAX3-FKHR fusion gene. Using the method of multidimensional scaling to represent the relationships among the cell lines in two-dimensional Euclidean space, we determined that ARMS cells show a consistent pattern of gene expression, which allows the cells to be clustered together. By searching across the seven ARMS cell lines, we found that 37 of 1238 genes were most consistently expressed in ARMS relative to a reference cell line. Only three of these genes have been previously reported to be expressed in ARMS. Among these 37 were genes related to both primary (PAX3-FKHR) and secondary (CDK4) genetic alterations in ARMS. These results in ARMS demonstrate the potential of cDNA microarray technology to elucidate tumor-specific gene expression profiles in human cancers.

MEK1 and MEK2 inhibitors and cancer therapy: the long and winding road.

Abstract: The role of the ERK signalling pathway in cancer is thought to be most prominent in tumours in which mutations in the receptor tyrosine kinases RAS, BRAF, CRAF, MEK1 or MEK2 drive growth factor-independent ERK1 and ERK2 activation and thence inappropriate cell proliferation and survival. New drugs that inhibit RAF or MEK1 and MEK2 have recently been approved or are currently undergoing late-stage clinical evaluation. In this Review, we consider the ERK pathway, focusing particularly on the role of MEK1 and MEK2, the 'gatekeepers' of ERK1/2 activity. We discuss their validation as drug targets, the merits of targeting MEK1 and MEK2 versus BRAF and the mechanisms of action of different inhibitors of MEK1 and MEK2. We also consider how some of the systems-level properties (intrapathway regulatory loops and wider signalling network connections) of the ERK pathway present a challenge for the success of MEK1 and MEK2 inhibitors, discuss mechanisms of resistance to these inhibitors, and review their clinical progress.

AZD6244 (ARRY-142886), a potent inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 kinases: mechanism of action in vivo, pharmacokinetic/pharmacodynamic relationship, and potential for combination in preclinical models

Abstract: Constitutive activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) signaling pathway in human cancers is often associated with mutational activation of BRAF or RAS. MAPK/ERK kinase 1/2 kinases lie downstream of RAS and BRAF and are the only acknowledged activators of ERK1/2, making them attractive targets for therapeutic intervention. AZD6244 (ARRY-142886) is a potent, selective, and ATP-uncompetitive inhibitor of MAPK/ERK kinase 1/2. In vitro cell viability inhibition screening of a tumor cell line panel found that lines harboring BRAF or RAS mutations were more likely to be sensitive to AZD6244. The in vivo mechanisms by which AZD6244 inhibits tumor growth were investigated. Chronic dosing with 25 mg/kg AZD6244 bd resulted in suppression of growth of Colo-205, Calu-6, and SW-620 xenografts, whereas an acute dose resulted in significant inhibition of ERK1/2 phosphorylation. Increased cleaved caspase-3, a marker of apoptosis, was detected in Colo-205 and Calu-6 but not in SW-620 tumors where a significant decrease in cell proliferation was detected. Chronic dosing of AZD6244 induced a morphologic change in SW-620 tumors to a more differentiated phenotype. The potential of AZD6244 in combination with cytotoxic drugs was evaluated in mice bearing SW-620 xenografts. Treatment with tolerated doses of AZD6244 and either irinotecan or docetaxel resulted in significantly enhanced antitumor efficacy relative to that of either agent alone. These results indicate that AZD6244 has potential to inhibit proliferation and induce apoptosis and differentiation, but the response varies between different xenografts. Moreover, enhanced antitumor efficacy can be obtained by combining AZD6244 with the cytotoxic drugs irinotecan or docetaxel.

Molecular classification of cancer: class discovery and class prediction by gene expression monitoring.

Abstract: Although cancer classification has improved over the past 30 years, there has been no general approach for identifying new cancer classes (class discovery) or for assigning tumors to known classes (class prediction). Here, a generic approach to cancer classification based on gene expression monitoring by DNA microarrays is described and applied to human acute leukemias as a test case. A class discovery procedure automatically discovered the distinction between acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) without previous knowledge of these classes. An automatically derived class predictor was able to determine the class of new leukemia cases. The results demonstrate the feasibility of cancer classification based solely on gene expression monitoring and suggest a general strategy for discovering and predicting cancer classes for other types of cancer, independent of previous biological knowledge.

Distinct types of diffuse large B-cell lymphoma identified by gene expression profiling

Abstract: 12 Pathology and Microbiology, and 13 Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma, is clinically heterogeneous: 40% of patients respond well to current therapy and have prolonged survival, whereas the remainder succumb to the disease. We proposed that this variability in natural history reflects unrecognized molecular heterogeneity in the tumours. Using DNA microarrays, we have conducted a systematic characterization of gene expression in B-cell malignancies. Here we show that there is diversity in gene expression among the tumours of DLBCL patients, apparently reflecting the variation in tumour proliferation rate, host response and differentiation state of the tumour. We identified two molecularly distinct forms of DLBCL which had gene expression patterns indicative of different stages of B-cell differentiation. One type expressed genes characteristic of germinal centre B cells ('germinal centre B-like DLBCL'); the second type expressed genes normally induced during in vitro activation of peripheral blood B cells ('activated B-like DLBCL'). Patients with germinal centre B-like DLBCL had a significantly better overall survival than those with activated B-like DLBCL. The molecular classification of tumours on the basis of gene expression can thus identify previously undetected and clinically significant subtypes of cancer.

The Cancer Cell Line Encyclopedia enables predictive modelling of anticancer drug sensitivity

Abstract: The systematic translation of cancer genomic data into knowledge of tumour biology and therapeutic possibilities remains challenging. Such efforts should be greatly aided by robust preclinical model systems that reflect the genomic diversity of human cancers and for which detailed genetic and pharmacological annotation is available. Here we describe the Cancer Cell Line Encyclopedia (CCLE): a compilation of gene expression, chromosomal copy number and massively parallel sequencing data from 947 human cancer cell lines. When coupled with pharmacological profiles for 24 anticancer drugs across 479 of the cell lines, this collection allowed identification of genetic, lineage, and gene-expression-based predictors of drug sensitivity. In addition to known predictors, we found that plasma cell lineage correlated with sensitivity to IGF1 receptor inhibitors; AHR expression was associated with MEK inhibitor efficacy in NRAS-mutant lines; and SLFN11 expression predicted sensitivity to topoisomerase inhibitors. Together, our results indicate that large, annotated cell-line collections may help to enable preclinical stratification schemata for anticancer agents. The generation of genetic predictions of drug response in the preclinical setting and their incorporation into cancer clinical trial design could speed the emergence of 'personalized' therapeutic regimens.

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.