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Personalized Cancer Cytometrics More Accurate than Molecular Gene Testing
By gdpawel at 2011-09-05 11:20
Personalized Cancer Cytometrics More Accurate than Molecular Gene Testing

 

Clinical Trial Finds Personalized Cancer Cytometrics More Accurate than Molecular Gene Testing

 

In the first head-to-head clinical trial comparing gene expression patterns with Personalized Cancer Cytometric testing (also known as “functional tumor cell profiling” or “chemosensitivity testing”), Personalized Cancer Cytometrics was found to be substantially more accurate.

 

In a clinical trial involving ovarian cancer patients, patterns of gene expression identified through molecular gene testing were compared with results of Personalized Cancer Cytometric testing (in which whole, living cancer cells are exposed to candidate chemotherapyterm drugs). Four different genes were included in the molecular part of the study. The four genes were selected as those which researchers believe to have the greatest likelihood of accurately predicting individual patient response to specific anti-cancer drugs.

 

Study Results:

 

For two of the genes studied, there was no significant correlation between gene expression pattern and patient response. In other words, results for these genes were found to be meaningless. For the third gene studied, there was a 75% correlation between expression and patient response. This means that the gene was 75% accurate when it came to identifying an active drug for that patient. For the fourth gene studied, the accuracy in identifying an active drug was only 25%. In marked contrast, Personalized Cancer Cytometric testing was found by the researchers to be 90% accurate in identifying active drugs for ovarian cancer patients in this study.

 

Discussion:

 

Molecular testing – that is, testing for gene expression patterns – is widely studied and heavily promoted as a method to identify effective chemotherapy drugs for individual cancer patients. However, most studies of molecular testing carried-out to date show only modest correlation or no correlation between test results and actual patient response. In other words, much work remains to be done before molecular gene testing can be regarded as an accurate tool for chemotherapy selection. And yet in this, first ever, head-to-head study of test accuracy, Personalized Cancer Cytometrics was found to be highly accurate when it came to identifying effective drugs.

 

Comparing this study with previous studies:

 

Although this was the first head-to-head trial, the accuracy levels found in this trial for Personalized Cancer Cytometric testing are strikingly consistent with those documented in dozens of previous studies, published by respected cancer researchers around the world. In those studies, as in this one, extremely high levels of correlation (in other words, high levels of test accuracy) were found for Personalized Cancer Cytometrics.

 

Arienti et al. Peritoneal carcinomatosis from ovarian cancer: chemosensitivity test and tissue markers as predictors of response to chemotherapy. Journal of Translational Medicine 2011, 9:94.

 

http://www.translational-medicine.com/content/9/1/94



7 comments | 19809 reads

by gdpawel on Sat, 2011-09-10 03:21
Peritoneal carcinomatosis from ovarian cancer: chemosensitivity test and tissue markers as predictors of response to chemotherapy

Chiara Arienti (1), Anna Tesei (1), Giorgio M Verdecchia (2), Massimo Framarini (2), Salvatore Virzì (3), Antonio Grassi (3), Emanuela Scarpi (1), Livia Turci (1), Rosella Silvestrini (1), Dino Amadori (1) and Wainer Zoli (1)

Author Affiliations

(1) Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (I.R.S.T.), Meldola, Italy

(2) Department of Surgery and Advanced Cancer Therapies, Morgagni-Pierantoni Hospital, Forlì, Italy

(3) Department of Surgery, Bentivoglio Hospital, Bologna, Italy

Abstract

Background:

Platinum-based regimens are the treatments of choice in ovarian cancer, which remains the leading cause of death from gynecological malignancies in the Western world. The aim of the present study was to compare the advantages and limits of a conventional chemosensitivity test with those of new biomolecular markers in predicting response to platinum regimens in a series of patients with peritoneal carcinomatosis from ovarian cancer.

Methods:

Fresh surgical biopsy specimens were obtained from 30 patients with primary or recurrent peritoneal carcinomatosis from ovarian cancer. ERCC1, GSTP1, MGMT, XPD, and BRCA1 gene expression levels were determined by Real-Time RT-PCR. An in vitro chemosensitivity test was used to define a sensitivity or resistance profile to the drugs used to treat each patient.

Results:

MGMT and XPD expression was directly and significantly related to resistance to platinum-containing treatment (p = 0.036 and p = 0.043, respectively). Significant predictivity in terms of sensitivity and resistance was observed for MGMT expression (75.0% and 72.5%, respectively; p = 0.03), while high predictivity of resistance (90.9%) but very low predictivity of sensitivity (37.5%) (p = 0.06) were observed for XPD. The best overall and significant predictivity was observed for chemosensitivity test results (85.7% sensitivity and 91.3% resistance; p = 0.0003).

Conclusions:

The in vitro assay showed a consistency with results observed in vivo in 27 out of the 30 patients analyzed. Sensitivity and resistance profiles of different drugs used in vivo would therefore seem to be better defined by the in vitro chemosensitivity test than by expression levels of markers.

Journal of Translational Medicine 2011, 9:94 doi:10.1186/1479-5876-9-94

The different genes that were studied in the molecular part of the above study were ERCC1, GSTP1, MGMT, XPD and BRCA1. These are putative drug resistance genes. ERCC and XPD are response elements for CDDP repair. BRCA1 is also a response element for DNA damage and part of FANC gene family (a genomic fidelity function).

GSTP1 is a detoxifying enzyme associated with thiol conjugation (alkylator resistance) while MGMT is the specific enzyme associated with the removal of temozolomide residues from DNA base pairs.

What the investigators did was to examine the (Caris) "Target Now" types of targets and compare clinical responses against the results with functional analyses, establishing that when one measures the biology of the disease it provides a more robust prediction of response. The "driver" term is less operative as these genes are not causative of the disease but causative of drug resistance.

Caris Lifesciences is a private company which does so-called “molecular” profiling, based on immunohistochemistry, FISH, RT-PCR, and molecular microarrays.

by gdpawel on Thu, 2011-09-22 12:20
By Margot J. Fromer
ASCO Post
September 1, 2011, Volume 2, Issue 13

If the clinical trials endeavor in oncology is falling short of its goals and if targeted agents have not kept their promise, can a new approach to drug development provide a solution?

Very possibly, said John Hohneker, MD, Chair of the Workshop Planning Committee for the conference, “Facilitating Collaborations to Develop Combination Investigational Cancer Therapies,” held in Washington in mid-June and sponsored by the Institute of Medicine (IOM) National Cancer Policy Forum. He is also Senior Vice President and Global Head of Development, Integrated Hospital Care, Novartis.

Dr. Hohneker said that the purpose of the workshop was to talk about the many barriers to this new approach to cancer treatment. “Combining investigational products early in their development is thought to be a promising strategy, especially when they target multiple pathways (or more than one step in a pathway), thus conferring greater benefit than therapy directed at a single target.”

Unfulfilled Promise

Jane Perlmutter, PhD, founder of the Gemini Group, a consulting company, added, “The problem with the way cancer research is conducted is that the biology of the disease is so complicated that, although technology keeps advancing, personalized medicine is still mostly only a promise.”

Targeted agents for cancer haven’t panned out to the extent hoped. Although a few might work sometimes or for a short time, the effects have not been significant or durable. And many are more toxic than expected. “Their regulation is confusing and/or interpreted too conservatively, and despite the great need, there is limited incentive for pharmaceutical companies to collaborate with each other,” said Dr. Perlmutter.

Advances in genomics and cell biology have paved the way for increasingly sophisticated targeted therapies, but cellular pathways contain redundancies that can be activated in response to inhibition of one or another pathway, thus promoting emergence of resistant cells and clinical relapse.

The traditional path to drug development, even targeted therapy, has been one at a time. Sometimes a new drug is added to a standard regimen and then compared to the standard alone, but regardless of how or with what it is used, it has to work on its own.

Cooperative Development

This system is no longer completely viable in cancer and needs to be modernized. A new approach would provide the flexibility to evaluate combination regimens in a single development program that can screen all tumors for their pathway dependencies, resulting in efficacy based on screening results and experience with patterns of resistance.

However, despite the potential benefits of such a scheme, uncertainty and risk abound. First, it is usually impossible to characterize the effects of the individual components. Second, combinations would probably yield considerably less information about safety and efficacy than would have been available had they been developed individually. Third, patients and physicians must not only be informed of more-than-usual risk, they must be willing to accept it. Fourth, there should be a compelling biologic rationale for their use and substantial reasons why the agents cannot be developed individually.

The Science Is Complex

James Doroshow, MD, Deputy Director for Clinical and Translational Research, NCI, discussed the scientific challenges facing development of combination targeted therapeutics:

The mechanisms of action for a growing number of targeted agents that are available for trials are not completely understood.

Lack of the right assays or imaging tools means inability to assess the target effect of many agents, and assays are not standardized.

Preclinical models to evaluate efficacy, dosing schedule effects, biomarker utility, and toxicity are not available for combination therapies.

Clinical trials methodology remains unclear with regard to numbers of patients, tumor biopsies, relevance of histologic homogeneity, and pharmacokinetic interactions.

Intellectual property and regulatory matters are daunting.

Dr. Doroshow also discussed mechanism of action (or mechanism of resistance) studies in early-phase trials. Problems include the evaluation of actual vs presumed sites of target engagement, evidence to support further development, demonstration of the relationship between dosing schedule and systemic exposure to target effects, and relevance of biomarkers.

“In addition, we need to investigate the molecular effects, toxicology, and other safety signals of combination agents in surrogate tissues,” said Dr. Doroshow. “This is a huge undertaking, and unfortunately it is not necessarily predictive of clinical benefit. That requires larger, later-stage trials.”

Michael T. Barrett, PhD, Associate Professor and Head of the Oncogenomics Laboratory, TGen, added that cancer is extremely genetically unstable, resulting in highly karyotypically and biologically individual malignancies. Thus, each patient’s cancer could require its own specific therapy. Even if this were possible and practical, the treatment could ultimately be thwarted by emergence of a resistant variant genetic subline.

Dr. Barrett also noted that each genome has unique sets of selected aberrations and mutations, of which multiple populations can be present at biopsy. These mutations can be asymmetric; they can progress and metastasize, and thus resist treatment. He warned that application of genomic tools to combination therapy has to be based on unbiased profiling of biopsies, as well as identification of therapeutic vulnerabilities in all patients.

Kurt Bachman, PhD, Head of Translational Medicine and Biology, GlaxoSmithKline, added, “The challenge is to identify the tumor types most likely to respond, to find biomarkers that predict a response, and to define the relationship of the predictors to the biology of the inhibitors.”

Disclosure: Dr. Hohneker is employed by and owns stock in Novartis. Dr. Barrett has a current research contract with AstraZeneca. Dr. Bachman is employed by GlaxoSmithKline. Dr. Perlmutter reported no potential conflicts of interest. Dr. Doroshow reported no potential conflicts of interest.

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