Identification of predictive and surrogate molecular markers for dasatinib in prostate cancer: Rationale for patient selection and efficacy monitoring

3579

Background: Dasatinib is a potent, multi-targeted kinase inhibitor that was recently approved for treatment of chronic myelogenous leukemia resistant to imatinib. To aid its clinical development in prostate cancer, we used a panel of prostate cancer cell lines to identify molecular markers that could be used to predict sensitivity to dasatinib and to monitor its activity. Methods: Baseline gene expression profiles of 16 cell lines were used to identify predictive biomarkers based on the correlation of gene expression with in vitro sensitivity of cells to dasatinib. Selected cell lines were treated with dasatinib to identify surrogate biomarkers based upon changes in gene expression following dasatinib treatment. Results: We identified 174 genes whose baseline expression levels were highly correlated with sensitivity or resistance to dasatinib. These include cell lineage markers cytokeratin 5 (CK5), androgen receptor (AR), and prostate specific antigen (PSA). Our results indicate that “basal type” cell lines (those with high expression of CK5 and low expression of AR and PSA) are sensitive to dasatinib. Dasatinib treatment studies further identified genes whose expression levels were significantly modulated by the drug. Ten genes, including urokinase-type plasminogen activator (uPA), were not only significantly correlated with sensitivity to dasatinib but also reduced in their expression upon drug treatment. In addition, the down-regulation of uPA was specific to dasatinib and the effect was not seen in taxol-treated cells. The extent of down-regulation was correlated with the sensitivity of cell lines to dasatinib. EphA2, a specific kinase target of dasatinib, was identified as a biomarker common to prostate and breast cancers. Finally, the expression of 5 genes including CK5, AR, PSA, uPA and EphA2 in prostate tumors was examined and the dasatinib sensitivity signature was validated using a published data set derived from a clinical population. Conclusions: Candidate markers correlated with dasatinib sensitivity were identified. A five-gene model consisting of predictive markers as well as potential surrogate markers has been formulated and will be evaluated in ongoing dasatinib prostate cancer trials.

No significant financial relationships to disclose.

Electrical activity during the 2006 Mount St. Augustine volcanic eruptions

By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases. First, there was an explosive phase in which the ejecta from the explosion appeared to be highly charged upon exiting the volcano, resulting in numerous apparently disorganized discharges and some simple lightning. The net charge exiting the volcano appears to have been positive. The second phase, which followed the most energetic explosion, produced conventional-type discharges that occurred within plume. Although the plume cloud was undoubtedly charged as a result of the explosion itself, the fact that the lightning onset was delayed and continued after and well downwind of the eruption indicates that in situ charging of some kind was occurring, presumably similar in some respects to that which occurs in normal thunderstorms.

The assessment of autonomic function in chronic atrial fibrillation: description of a non-invasive technique based on circadian rhythm of atrioventricular nodal functional refractory periods

AIMS

Heart rate variability (HRV) parameters can be used to assess autonomic function and to predict outcome, but this has been done exclusively in patients with sinus rhythm. Atrial fibrillation (AF) is the commonest sustained arrhythmia and is particularly prevalent in heart failure. We have developed a simple index to assess autonomic function in patients with chronic AF.

METHODS AND RESULTS

Forty patients with chronic AF (>1 month) and symptoms of heart failure underwent ambulatory 24 h electrocardiography recording as well as evaluation of symptoms, exercise capacity (6 min walk distance), ventricular function (echocardiography and radionuclide ventriculography), and neuroendocrine activation. A number of standard HRV parameters shown to have prognostic significance in sinus rhythm were also determined. A modified in-house HRV statistical programme was used to filter labelled QRS intervals and to compute the 5th percentile RR interval in each hour. This parameter has been shown to approximate the functional refractory period (FRP) of the atrioventricular node (AVN). A cosine curve was fitted to hourly 5th percentile RR intervals for each patient and from this was estimated the diurnal change in hourly 5th percentile RR interval (approximating DeltaFRP of the AVN) and, by inference, diurnal variation in sympathovagal input to the AVN. Digoxin was the sole agent permitted for control of ventricular rate. DeltaFRP of the AVN varied and revealed a significant correlation, on multivariate analysis, with mean RR interval (P<0.001), SDARR (SD of 5-min average RR intervals during 24 h, P<0.001), and NYHA class of heart failure (classes III and IV heart failure vs. classes I and II, P=0.02). SDARR has previously been shown independently to predict mortality in patients with chronic AF and heart failure.

CONCLUSION

This analysis describes a novel non-invasive method for assessing autonomic function in chronic AF. Whether DeltaFRP in chronic AF patients can independently predict adverse prognosis or sudden death requires further study.

Perioperative transfusion for pancreaticoduodenectomy and its impact on prognosis in resected pancreatic ductal adenocarcinoma

BACKGROUND AND AIMS

Pancreaticoduodenectomy (PD) is a major operative intervention performed most commonly for malignancy in the head of pancreas. The aim of this study was to evaluate the utilization of blood transfusion for PD and to determine whether this had prognostic significance in a subset of patients with pancreatic ductal adenocarcinoma (PDAC).

MATERIAL AND METHODS

Data on blood transfusion requirement were retrospectively collected for patients undergoing PD from 1998 to 2005. Standard prognostic factors and survival data were also collected in patients with PDAC.

RESULTS

One-hundred-and-seventy patients underwent PD. Seventy-six patients (45%) received transfusion. The median (interquartile range) number of units of red cell concentrate (RCC) transfused perioperatively (intraoperatively and within 24 h of surgery) was 1.5 (0.5-2.5). The median preoperative haemoglobin (Hb) was 126 g/dl. The median number of units of RCC transfused perioperatively in patients with Hb <126 g/dl was 2 (1-3); for those with Hb > or = 126 g/dl the median was 0 (0-1); p=0.003. Forty-nine patients who were resected for PDAC were subjected to survival analysis. Univariate and multivariate analyses showed that only posterior resection margin invasion was associated with an adverse outcome (margin positive 198 [143-470] days vs margin negative 398 [303-859] days; p=0.02). Perioperative RCC transfusion requirement was not a significant predictor of survival (transfusion 408 [214-769] days vs no transfusion 331 [217-391] days; p=0.18). Furthermore, RCC transfusion within 30 days of operation was not a significant predictor of poor survival (transfusion 331 [201-459] days vs no transfusion 317 [196-769] days; p=0.43).

CONCLUSIONS

PD can be performed with a moderately low requirement for RCC transfusion; however, low preoperative haemoglobin is a predictor for the requirement of RCC transfusion. Administration of RCC transfusion does not appear to be a significant adverse prognostic factor in patients with resected PDAC.

Predictive biomarker discovery and validation for the targeted chemotherapeutic ixabepilone

3011

Background: Ixabepilone is a microtubule stabilizing agent with significant therapeutic value in breast cancer (BC) patients. To identify predictive biomarkers capable of identifying patients likely to receive optimal benefit from ixabepilone treatment, preclinical and clinical studies were carried out. Several biomarkers discovered using preclinical models were validated in a neoadjuvant BC clinical study ( CA163080 ) and one, estrogen receptor 1 (ER), was shown to double the pathological complete response (pCR) rate in patients treated with ixabepilone. To identify candidate sets of biomarkers that could further increase the pCR rate we have performed post-hoc analyses of the preclinical and clinical data. Methods: Eighteen BC cell lines were classified as sensitive or resistant (S/R) based on the IC50 values for ixabepilone treatment. Gene expression profiling of the BC cell lines was conducted and genes correlated with the S/R classification were identified using a k-Nearest Neighbors algorithm. Patients in clinical study CA163080 underwent a pretreatment core needle biopsy from which RNA was isolated and gene expression profiles generated (data available on 134 patients). Analyses using the preclinical and clinical markers were conducted using various statistical tools. Results: Several markers used in combination with ER were found to be capable of tripling the pCR to ixabepilone in CA163080. In addition to ER other predictive markers were identified that were as predictive as ER, including several genes whose expression is anti-correlated with ER and are part of the ER pathway. Finally, various sub-group analyses were performed and manifested the importance of clinical sample variation that needs to be considered for the analysis. Conclusions: Several single biomarkers identified from preclinical studies were validated in the clinical study CA163080 , demonstrating the utility of this approach. Such markers can be used in combination to better identify patients likely to respond to ixabepilone in future clinical trials. Furthermore, molecular response markers that can be tied to the mechanism of drug resistance can be used for further developing chemotherapy in drug development.

[Table: see text]

Microtubule Associated Protein (MAP)-Tau: a novel mediator of paclitaxel sensitivity in vitro and in vivo

Microtubule binding protein Tau was recently identified through gene expression analysis of human breast cancer tissues as a novel marker of response to paclitaxel. This article reviews these recent findings and provides additional information to support the role of Tau as an emerging marker and mediator of paclitaxel sensitivity. Low expression of Tau is associated with increased sensitivity to paclitaxel in human breast cancer as well as in a broad range of cell lines. Down regulation of Tau in cell lines by siRNA increases their sensitivity to paclitaxel but not to anthracycline chemotherapy. We propose that this is due to increased paclitaxel binding to microtubules when microtubules are assembled in the presence of low concentrations (or absence) of Tau compared to microtubules that are formed in the presence of physiological (or higher) levels of Tau.

Low-skill fibreoptic intubation: use of the Aintree Catheter with the classic LMA

We describe a series of patients in whom anaesthetists - many of whom were trainees and had no prior experience of using the Aintree Intubation Catheter - successfully intubated the tracheas of patients in whom conventional attempts at intubation had failed. This was achieved by passing a fibrescope loaded with an Aintree Intubation Catheter through a classic Laryngeal Mask Airway (cLMA), which had already been placed to maintain the patient's airway.

Heart rate variability fraction--a new reportable measure of 24-hour R-R interval variation

BACKGROUND

The scatterplot of R-R intervals has several unique features. Its numerical evaluation may produce a new useful index of global heart rate variability (HRV) from Holter recordings.

METHODS

Two-hundred and ten middle-aged healthy subjects were enrolled in this study. The study was repeated the next day in 165 subjects. Each subject had a 24-hour ECG recording taken. Preprocessed data were transferred into a personal computer and the standard HRV time-domain indices: standard deviation of total normal R-R intervals (SDNN), standard deviation of averaged means of normal R-R intervals over 5-minute periods (SDANN), triangular index (TI), and pNN50 were determined. The scatterplot area (0.2-1.8 second) was divided into 256 boxes, each of 0.1-second interval, and the number of paired R-R intervals was counted. The heart rate variability fraction (HRVF) was calculated as the two highest counts divided by the number of total beats differing from the consecutive beat by <50 ms. The HRVF was obtained by subtracting this fraction from 1, and converting the result to a percentage.

RESULTS

The normal value of the HRVF was 52.7 +/- 8.6%. The 2-98% range calculated from the normal probability plot was 35.1-70.3%. The HRVF varied significantly with gender (female 48.7 +/- 8.4% vs male 53.6 +/- 8.6%, P = 0.002). The HRVF correlated with RRI (r = 0.525) and showed a similar or better relationship with SDNN (0.851), SDANN (0.653), and TI (0.845) than did the standard HRV measures with each other. Bland-Altman plot showed a good day-by-day reproducibility of the HRVF, with the intraclass correlation coefficient of 0.839 and a low relative standard error difference (1.8%).

CONCLUSION

We introduced a new index of HRV, which is easy for computation, robust, reproducible, easy to understand, and may overcome the limitations that belong to the standard HRV measures. This index, named HRV fraction, by combining magnitude, distribution, and heart-rate influences, might become a clinically useful index of global HRV.

Modification of ACC/ESC criteria for acute myocardial infarction

The American College of Cardiology (ACC) and European Society of Cardiology (ESC) recently proposed criteria for acute ST elevation myocardial infarction (STEMI). These criteria were based on STj >0.1 mV in limbs leads and V4-V6, or STj >0.2 mV in V1 to V3 with criteria being met in two contiguous leads. The criteria were neither age nor sex dependent and the aim of the present study was to evaluate whether or not improved STEMI criteria that were age and gender dependent could be developed. A training set of 789 ECGs from patients presenting with chest pain due to cardiac and other causes was available for study. Revised criteria for STEMI were developed using these data as well as ECGs from a normal adult population of 859 males and 637 females. A test set of ECGs was available in the form of 1220 ECGs recorded from a separate hospital from patients presenting with chest pain. 248 patients had an acute myocardial infarction on the basis of conventional clinical criteria while 972 did not. There was an improvement in sensitivity using the new criteria compared to the old criteria from 41.5% to 46.7% while specificity improved from 96.0% to 98.5%. Specificity in normals improved from 92.6% to 99.8%. The conclusion drawn is that while the ACC/ESC criteria are simple to apply, they are not particularly specific and can be improved by being supplemented by other ECG measures and optimized for age and sex.

Gene expression profiles predict complete pathologic response to neoadjuvant paclitaxel and fluorouracil, doxorubicin, and cyclophosphamide chemotherapy in breast cancer

PURPOSE

The goal of this study was to examine the feasibility of developing a multigene predictor of pathologic complete response (pCR) to sequential weekly paclitaxel and fluorouracil + doxorubicin + cyclophosphamide (T/FAC) neoadjuvant chemotherapy regimen for breast cancer.

PATIENTS AND METHODS

All patients underwent one-time pretreatment fine-needle aspiration to obtain RNA from the cancer for transcriptional profiling using cDNA arrays containing 30721 human sequence clones. Analysis was performed after profiling, and 42 patients' clinical results were available, 24 of which were used for predictive marker discovery; 18 patients' results were used as an independent validation set.

RESULTS

Thirty-one percent of patients had pCR (six discovery and seven validation), defined as disappearance of all invasive cancer in the breast after completion of chemotherapy. We could identify no single marker that was sufficiently associated with pCR to be used as an individual predictor. A multigene model with 74 markers (P <or=.09) was built using data from the discovery samples and tested on the validation samples. Overall, a 78% (14 of 18) predictive accuracy was observed, with a 100% (three of three) positive predictive value for pCR, a 73% (11 of 15) negative predictive value, a sensitivity of 43% (three of seven), and a specificity of 100% (11 of 11). The expected response rate to T/FAC neoadjuvant therapy in unselected patients is 28%.

CONCLUSION

Our results suggest that transcriptional profiling has the potential to identify a gene expression pattern in breast cancer that may lead to clinically useful predictors of pCR to T/FAC neoadjuvant therapy.

Porcine circovirus-2 and concurrent infections in the field

Porcine circovirus-2 (PCV-2) is the necessary cause of post-weaning multisystemic wasting syndrome (PMWS) in swine; however, a variety of co-factors, including other infectious agents, are thought to be necessary in the full expression of disease. Porcine parvovirus (PPV) was found in the inoculum used in the first experiments to reproduce PMWS in gnotobiotic swine. Retrospective and prospective studies in the field and laboratory have demonstrated PCV-2 can act synergistically with PPV to enhance the severity of PMWS. PCV-2 has been shown to play a role in the porcine infectious disease complex (PRDC). Other co-infecting agents with PCV-2 in the lung include, porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV) and Mycoplasma hyopneumoniae. Exposure of pregnant sows to PPV, PRRSV, or encephalomyocarditis virus may interact with PCV-2 infected foetuses. The severity of hepatic lesions in PCV-2 infected pigs may be enhanced by co-infection with agents such as swine hepatitis E virus and Aujezsky's disease virus. Additional studies are required to determine the mechanistic basis for the interaction of PCV-2 with other agents in the pathogenesis of the various clinical syndromes that have been associated with PCV-2 infection.

Advancing self-determination with young adults who have schizophrenia

The research examined how community mental health nurses promote self-determination with clients who are experiencing an early episode of schizophrenia. The study used grounded theory methodology incorporating interviews and observations. The study took place in the community, in rural and regional New South Wales, Australia, and involved clients and community mental health nurses. The findings show that the promotion of self-determination is dependent on nurses educating clients about their illness and well-being, and fostering self-control. The development of a reciprocal relationship, or alliance, between nurses and clients is implicit in advancing self-determination. The implications of the promotion of client self-determination for education, clinical practice and research and these are discussed.

Effects of phosphodiesterase inhibitors on oesophageal neuromuscular functions

The cyclic nucleotides adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) mediate the inhibitory effects of vasoactive intestinal polypeptide and nitric oxide on oesophageal smooth muscle. Phosphodiesterases (PDE) terminate their actions. We hypothesized that PDE inhibitors alter nerve-induced responses of oesophageal and lower oesophageal sphincter (LES) smooth muscle. An electrical field known to activate intrinsic oesophageal nerves was used to stimulate transverse muscle strips from the opossum oesophagus. This produced a contractile off-response from circular oesophageal muscle and a biphasic relaxation of the LES - an initial rapid relaxation (R1) and a slower sustained relaxation (R2). The effects on LES and oesophageal muscle of zaprinast (type V), zardaverine (type III/IV) and theophylline (non-specific) PDE inhibitors were explored. All three PDE inhibitors decreased LES tone and attenuated the off-response. Zaprinast and theophylline increased the latency of the off-response. Zaprinast prolonged R1, and slowed its recovery. It also increased the percentage relaxation of the second R2. Zardaverine increased the percentage relaxation of R2. Theophylline slowed the recovery of R2. PDEs play a role in maintaining LES tone and its recovery after LES relaxation. They may also modulate oesophageal motor activity.