HER2 Support Group Forums - View Single Post - FISH Technology Preferred For Choosing HER-2-Positive Breast Cancer Treatments

gdpawel · 01-04-2010, 01:52 PM

It's posted on both Breast Cancer Newsfeed and General Cancer News. I'll post my response to your good questions here too.

There is a headlong rush to develop tests to identify molecular predisposing mechanisms, whose presence still does not guarantee that a drug will be effective for an individual patient. Nor can they, for any patient or even large group of patients, discriminate the potential for clinical activity among different agents of the same class.

The challenge is to identify which patients targeted treatment will be most effective. Tumors can become resistant to a targeted treatment, or the drug no longer works, even if it has previously been effective in shrinking a tumor. Drugs are combined with existing ones to target the tumor more effectively. Most cancers cannot be effectively treated with targeted drugs alone.

Paraffin embedded, fixed, minced, or frozen tissue can change over time. One gets more accurate information when using intact RNA isolated from "fresh" living tissue than from using degraded RNA, which is present in paraffin-fixed tissue.

It is established "cell-line" that is not reflective of the behavior of fresh tumor cells in primary culture in the lab, much less in the patient. You get different results when you test passaged cells compared to primary, fresh tumors.

NCI had their own personal experience. At a NCI-sponsored Ovarian Cancer State of the Science Meeting in 2005, it was brought out that NCI had a huge lab working on microarrays to look for patterns of mRNA and protein expression which are predictive of chemotherapy response.

They spent 2 years trying to find patterns which correlated using the NCI's various established ovarian "cell-lines." They thought they had something, but when they started to apply them to "fresh" tumor specimens, none of the results in the "cell-lines" was applicable to the "fresh" tumors. Everything they'd worked out in the "cell-lines" was not worth anything and they had to start over from square one.

Critics of the cell-death assay procedure contend that cells do not necessarily react the same in the laboratory (in vitro) as they do in the body (in vivo). However, tests are performed using intact, living (fresh) cancer cells plated in 3D microclusters, which is indicative of what will happen in the human body.

Three-dimensional microclusters of tumor cells are isolated from fresh tumor biopsy specimens and cultured for 96 hours (polypropylene, round-bottomed, 96-well microplates) in the presence and absence of test drugs. Polypropylene is a slippery material which prevents the attachment of fibroblasts and epithelial cells and encourages the tumor cells to remain in the form of three dimensional, floating clusters. Real life 3D analysis make the assays indicative of what will happen in the body.

What is needed is to measure the net effect of all processes within the cancer, acting with and against each other in real time, and test living cells actually exposed to drugs and drug combinations of interest. The key to understanding the genome is understanding how cells work. How is the cell being killed regardless of the mechanism?

Cell culture testing methods assess the net effect of all inter-cellular and intra-cellular processes occurring in real time when cells are exposed to anti-cancer agents. Molecular testing methods detect the presence or absence of selected gene mutations which theoretically correlate with single agent drug activity. Cells are never exposed to anti-cancer agents.

Cell culture testing methods are performed using intact, living cancer cells plated in 3D microclusters. It allows for testing of different drugs within the same class and drug combinations to detect drug synergy and drug antagonism.

The core understanding is the cell, composed of hundreds of complex molecules that regulate the pathways necessary for vital cellular functions. If a targeted drug could perturb any of these pathways, it is important to examine the effects of drug combinations within the context of the cell.

Both genomics and proteomics can identify potential therapeutic targets, but these targets require the determination of cellular endpoints. You still need to measure the net effect of all processes, not just the individual molecular targets.

Literature Citation:
Eur J Clin Invest, Volume 37(suppl. 1):60, April 2007
BMJ 2007;334(suppl 1):s18 (6 January), doi:10.1136/bmj.39034.719942.94

01-04-2010, 01:52 PM	#4
gdpawel Senior Member Join Date: Aug 2006 Location: Pennsylvania Posts: 1,080	Re: FISH Technology Preferred For Choosing HER-2-Positive Breast Cancer Treatments It's posted on both Breast Cancer Newsfeed and General Cancer News. I'll post my response to your good questions here too. There is a headlong rush to develop tests to identify molecular predisposing mechanisms, whose presence still does not guarantee that a drug will be effective for an individual patient. Nor can they, for any patient or even large group of patients, discriminate the potential for clinical activity among different agents of the same class. The challenge is to identify which patients targeted treatment will be most effective. Tumors can become resistant to a targeted treatment, or the drug no longer works, even if it has previously been effective in shrinking a tumor. Drugs are combined with existing ones to target the tumor more effectively. Most cancers cannot be effectively treated with targeted drugs alone. Paraffin embedded, fixed, minced, or frozen tissue can change over time. One gets more accurate information when using intact RNA isolated from "fresh" living tissue than from using degraded RNA, which is present in paraffin-fixed tissue. It is established "cell-line" that is not reflective of the behavior of fresh tumor cells in primary culture in the lab, much less in the patient. You get different results when you test passaged cells compared to primary, fresh tumors. NCI had their own personal experience. At a NCI-sponsored Ovarian Cancer State of the Science Meeting in 2005, it was brought out that NCI had a huge lab working on microarrays to look for patterns of mRNA and protein expression which are predictive of chemotherapy response. They spent 2 years trying to find patterns which correlated using the NCI's various established ovarian "cell-lines." They thought they had something, but when they started to apply them to "fresh" tumor specimens, none of the results in the "cell-lines" was applicable to the "fresh" tumors. Everything they'd worked out in the "cell-lines" was not worth anything and they had to start over from square one. Critics of the cell-death assay procedure contend that cells do not necessarily react the same in the laboratory (in vitro) as they do in the body (in vivo). However, tests are performed using intact, living (fresh) cancer cells plated in 3D microclusters, which is indicative of what will happen in the human body. Three-dimensional microclusters of tumor cells are isolated from fresh tumor biopsy specimens and cultured for 96 hours (polypropylene, round-bottomed, 96-well microplates) in the presence and absence of test drugs. Polypropylene is a slippery material which prevents the attachment of fibroblasts and epithelial cells and encourages the tumor cells to remain in the form of three dimensional, floating clusters. Real life 3D analysis make the assays indicative of what will happen in the body. What is needed is to measure the net effect of all processes within the cancer, acting with and against each other in real time, and test living cells actually exposed to drugs and drug combinations of interest. The key to understanding the genome is understanding how cells work. How is the cell being killed regardless of the mechanism? Cell culture testing methods assess the net effect of all inter-cellular and intra-cellular processes occurring in real time when cells are exposed to anti-cancer agents. Molecular testing methods detect the presence or absence of selected gene mutations which theoretically correlate with single agent drug activity. Cells are never exposed to anti-cancer agents. Cell culture testing methods are performed using intact, living cancer cells plated in 3D microclusters. It allows for testing of different drugs within the same class and drug combinations to detect drug synergy and drug antagonism. The core understanding is the cell, composed of hundreds of complex molecules that regulate the pathways necessary for vital cellular functions. If a targeted drug could perturb any of these pathways, it is important to examine the effects of drug combinations within the context of the cell. Both genomics and proteomics can identify potential therapeutic targets, but these targets require the determination of cellular endpoints. You still need to measure the net effect of all processes, not just the individual molecular targets. Literature Citation: Eur J Clin Invest, Volume 37(suppl. 1):60, April 2007 BMJ 2007;334(suppl 1):s18 (6 January), doi:10.1136/bmj.39034.719942.94