RNA editing study under intense scrutiny : Nature News & Comment

RNA editing study under intense scrutiny 

The idea that RNA is often edited after being transcribed from DNA is a controversial one.

PASIEKA/SCIENCE PHOTO LIBRARY

Medscape: New Medical Admissions Test for New Generation of Physicians

New Medical Admissions Test for New Generation of Physicians

"People who have taken the MCAT see it as an exam that emphasizes physics, chemistry, and math, first and foremost, Darrell Kirch, MD, president and chief executive officer of the Association of American Medical Colleges, said in a video on the association's Web site."

OncoLink launches redesigned website based on search habits and feedback from patients, caregivers

OncoLink launches redesigned website based on search habits and feedback from patients, caregivers:

OncoLink, a free cancer information website developed by experts at the University of Pennsylvania's Abramson Cancer Center has launched a redesigned website based on the search habits and feedback from patients, caregivers and health care providers who use the site.

abstract: Shared Genetic Basis for Breast Cancer and Breast Density

Shared Genetic Basis for Breast Cancer and Breast Density:

" Together, our results show that PMD and breast cancer have a shared genetic basis that is mediated through a large number of common variants."

Percent mammographic breast density (PMD) is a strong heritable risk factor for breast cancer. However, the pathways through which this risk is mediated are still unclear. To explore whether PMD and breast cancer have a shared genetic basis, we identified genetic variants most strongly associated with PMD in a published meta-analysis of five genome-wide association studies (GWAS) and used these to construct risk scores for 3,628 breast cancer cases and 5,190 controls from the UK2 GWAS of breast cancer.

abstract: Phase 1 Dose-Escalation Study of Aflibercept Plus Docetaxel

Phase 1 Dose-Escalation Study of Aflibercept Plus Docetaxel:

Purpose: This phase I study cohort investigated aflibercept in combination with docetaxel in patients with advanced solid tumors.

Materials and Methods: Eligible patients had metastatic or nonresectable cancer for which docetaxel was considered appropriate. Patients received intravenous aflibercept (either 2, 4, 5, 6, 7, or 9 mg/kg) with docetaxel (75 mg/m²) on day 1 every 3 weeks until disease progression or unacceptable toxicity. Primary objectives were to evaluate dose-limiting toxicities (DLT) during cycle 1 and to determine the aflibercept recommended phase II trial dose (RP2D) for combination with docetaxel. Pharmacokinetics, tolerability, and antitumor activity were also investigated.

Results: Fifty-four patients (mean age, 56 y) were enrolled. Most had prior chemotherapy (96%) and most (24.1%) had breast cancer. In the dose-escalation phase (n = 34), there were three DLTs: grade 4 neutropenic infection (2 mg/kg), grade 3 dysphonia (7 mg/kg), and grade 2 hypertension (9 mg/kg). An excess of free-over-bound aflibercept was observed at doses of 5 mg/kg or more. The pharmacokinetics of aflibercept and docetaxel were not modified by coadministration. Aflibercept (6 mg/kg) was defined as the RP2D based on DLT and pharmacokinetic data.
Overall, the most frequent grade 3/4 adverse events (AE) were neutropenia (85.2%), leukopenia (74.1%), hypertension (18.5%), and stomatitis (16.7%). AEs associated with vascular endothelial growth factor blockade included epistaxis (all grades, 83.3%), proteinuria (68.5%), dysphonia (68.5%), and hypertension (53.7%). Seven patients had partial responses, and 32 patients had stable disease (>3 months in 18 patients).

Conclusion: On the basis of findings from this study, aflibercept (6 mg/kg) was the dose recommended for further clinical development. Clin Cancer Res; 18(6); 1743–50. ©2012 AACR.

abstract: Evaluation of Iniparib as a PARP Inhibitor (BRCA2....)

Evaluation of Iniparib as a PARP Inhibitor:

Purpose:

Poly(ADP-ribose) polymerase (PARP) inhibitors are undergoing extensive clinical testing for their single-agent activity in homologous recombination (HR)-deficient tumors and ability to enhance the action of certain DNA-damaging agents. Compared with other PARP inhibitors in development, iniparib (4-iodo-3-nitrobenzamide) is notable for its simple structure and the reported ability of its intracellular metabolite 4-iodo-3-nitrosobenzamide to covalently inhibit PARP1 under cell-free conditions. The present preclinical studies were conducted to compare the actions iniparib with the more extensively characterized PARP inhibitors olaparib and veliparib.

Results:

Consistent with earlier reports, olaparib and veliparib selectively induced apoptosis and inhibited colony formation in cells lacking BRCA2 or ATM. Moreover, like earlier generation PARP inhibitors, olaparib and veliparib sensitized cells to the topoisomerase I poisons camptothecin and topotecan. Finally, olaparib and veliparib inhibited formation of pADPr in intact cells. In contrast, iniparib exhibited little or no ability to selectively kill HR-deficient cells, sensitize cells to topoisomerase I poisons, or inhibit pADPr formation in situ. In further experiments, iniparib also failed to sensitize cells to cisplatin, gemcitabine, or paclitaxel.


Conclusions:

While iniparib kills normal and neoplastic cells at high (>40 μmol/L) concentrations, its effects are unlikely to reflect PARP inhibition and should not be used to guide decisions about other PARP inhibitors.  

Clin Cancer Res; 18(6); 1655–62. ©2012 AACR.

abstract: Impact of Preanalytic Factors on the Design and Application of Integral Biomarkers

Impact of Preanalytic Factors on the Design and Application of Integral Biomarkers:

Molecular assays have been routinely applied to improve diagnosis for the last 25 years. Assays that guide therapy have a similar history; however, their evolution has lacked the focus on analytic integrity that is required for the molecularly targeted therapies of today. New molecularly targeted agents require assays of greater precision/quantitation to predict the likelihood of response, i.e., to identify patients whose tumors will respond, while at the same time excluding and protecting those patients whose tumors will not respond or in whom treatment will cause unacceptable toxicity. The handling of tissue has followed a fit-for-purpose approach focused on appropriateness for diagnostic needs, which is less rigorous than the demands of new molecular assays that interrogate DNA, RNA, and proteins in a quantitative, multiplex manner. There is a new appreciation of the importance and fragility of tissue specimens as the source of analytes to direct therapy. By applying a total test paradigm and defining and measuring sources of variability in specimens, we can develop a set of specifications that can be incorporated into the clinical-care environment to ensure that a specimen is appropriate for analysis and will return a true result. 

abstract: Leveling the Playing Field: Bringing Development of Biomarkers and Molecular Diagnostics up to the Standards for Drug Development

Leveling the Playing Field: Bringing Development of Biomarkers and Molecular Diagnostics up to the Standards for Drug Development

 "....One way to accomplish this is to emphasize phase IV postmarketing, hypothesis-driven clinical trials with biological characterization that would permit an accurate definition of the association of low-prevalence gene alterations with toxicity or response in large cohorts."

Drug data reveal sneaky side effects : Nature News & Comment

Drug data reveal sneaky side effects : Nature 

 Mining of surveillance data highlights thousands of previously unknown consequences when drugs are taken together.

14 March 2012

An algorithm designed by US scientists to trawl through a plethora of drug interactions has yielded thousands of previously unknown side effects caused by taking drugs in combination.
The work, published today in Science Translational Medicine¹, provides a way to sort through the hundreds of thousands of 'adverse events' reported to the US Food and Drug Administration (FDA) each year. “It’s a step in the direction of a complete catalogue of drug–drug interactions,” says the study's lead author, Russ Altman, a bioengineer at Stanford University in California.........“Even if you show a drug is safe in a clinical trial, that doesn’t mean it’s going to be safe in the real world,” says Paul Watkins, director of the Hamner–University of North Carolina Institute for Drug Safety Sciences in Research Triangle Park, North Carolina, who was not involved in the work. “This approach is addressing a better way to rapidly assess a drug’s safety in the real world once it is approved.”.....