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Patient-Specific Cancer Cell Lines Designed To Predict Chemotherapy Sensitivity

gdpawel's picture
gdpawel
Posts: 549
Joined: May 2001

In laboratory studies, scientists at the Johns Hopkins Kimmel Cancer Center have developed a way to personalize chemotherapy drug selection for cancer patients by using cell lines created from their own tumors. 

If the technique is successful in further studies, it could replace current laboratory tests to optimize drug selection that have proven technically challenging, of limited use, and slow, the researchers say. 

Oncologists typically choose anticancer drugs based on the affected organs' location and/or the appearance and activity of cancer cells when viewed under a microscope. Some companies offer commercial tests on surgically removed tumors using a small number of anticancer drugs. But Anirban Maitra, MBBS, professor of pathology and oncology at the Johns Hopkins University School of Medicine, says the tissue samples used in such tests may have been injured by anesthetic drugs or shipping to a lab, compromising test results. 

By contrast, he says "our cell lines better and more accurately represent the tumors, and can be tested against any drug library in the world to see if the cancer is responsive." 

The Johns Hopkins scientists developed their test-worthy cell lines by injecting human pancreatic and ovarian tumor cells into mice genetically engineered to favor tumor growth. Once tumors grew to one centimeter in diameter in the mice, the scientists transferred the tumors to culture flasks for additional studies and tests with anticancer drugs. 

In one experiment, they successfully pinpointed the two anticancer drugs from among more than 3,000 that were the most effective in killing cells in one of the pancreatic cancer cell lines. A report on the success was published online recently in the journal Clinical Cancer Research. 

The new method was designed to overcome one of the central problems of growing human tumor cell lines in a laboratory dish -- namely the tendency of noncancerous cells in a tumor to overgrow cancerous ones, says James Eshleman, M.D., Ph.D., professor of pathology and oncology and associate director of the Molecular Diagnostics Laboratory at Johns Hopkins. As a consequence, it has not been possible to conventionally grow cell lines for some cancers. Still other cell lines, Eshleman says, don't reflect the full spectrum of disease. 

To solve the problem of overcrowding by noncancerous cells, Maitra and Eshleman bred genetically engineered mice that replace the noncancerous cells with mouse cells that can be destroyed by chemicals, leaving pure human tumor cells for study. 

"Our technique allows us to produce cell lines where they don't now exist, where more lines are needed, or where there is a particularly rare or biologically distinctive patient we want to study," says Eshleman. 

In its proof of concept research, the Johns Hopkins team created three pancreatic ductal adenocarcinoma cell lines and one ovarian cancer cell line. They then tested one of the pancreatic cancer cell lines (called Panc502) against the Johns Hopkins Drug Library of 3,131 drugs, identifying tumor cells most responsive to the anticancer drugs digitoxin and nogalamycin. 

For 30 days, they watched the effects in living mice of the two drugs and a control medicine on tumors grown from implanted cells derived from Panc502 and an additional pancreatic cell line, Panc410. They measured the size of tumors twice a week. Both drugs demonstrated more activity in reducing the tumor appearance and size in Panc502 than in Panc410, supporting the notion that the cell line technology may better predict sensitivity to the two drugs. 

The investigators have given one type of their genetically engineered mice to The Jackson Laboratory in Bar Harbor, ME, a mouse genetics research facility, for breeding and distribution to other laboratories and are looking to partner with a company to distribute two other types.

References:

Study co-authors were Hirohiko Kamiyama, Sherri Rauenzahn, Joong Sup Shim, Collins A. Karikari, Georg Feldmann, Li Hua, Mihoko Kamiyama, F. William Schuler, Ming-Tseh Lin, Robert M. Beaty, Balasubramanyam Karanam, Hong Liang, Michael E. Mullendore, Guanglan Mo, Manuel Hidalgo, Elizabeth Jaffee, Ralph H. Hruban, Richard B. S. Roden, Antonio Jimeno, and Jun O. Liu, of Hopkins; and H. A. Jinnah of Emory University School of Medicine in Atlanta. 

The work was supported by the National Institutes of Health, National Cancer Institute (CA130938, CA62924 and CA122581), the Sol Goldman Pancreatic Cancer Research Center, the Stewart Trust Fund, the Lustgarten Foundation, the Mary Lou Wootton Pancreatic Pancreatic Cancer Research Fund, the Michael Rolfe Pancreatic Cancer Foundation and the HERA Foundation. 

Rauenzahn, Maitra and Eshleman may receive royalty payments if the mice are licensed, and Eshleman is an advisory board member for Roche Molecular Diagnostics. These relationships have been disclosed and are under the management of the Johns Hopkins University School of Medicine Conflict of Interest Committee.

Citation: Johns Hopkins Medicine. "Patient-Specific Cancer Cell Lines Designed To Predict Chemotherapy Sensitivity." Medical News Today. MediLexicon, Intl., 19 Feb. 2013

gdpawel's picture
gdpawel
Posts: 549
Joined: May 2001

Patient-Specific Biomarker Information to Generate a Treatment Approach

Cell-lines (as described in the article above) are useful for experimentation in labs as they are always available to researchers as a product and do not require harvesting (acquiring of tissue from a host) every time cells are needed in the lab.

Problem is, cell-lines don't recapitulate drug response patterns which exist in the body. For drug selection, it is better to directly remove tumor "microclusters" straight from the body and immediately test them, before they change.

The problem with using cell-lines is that they do not predict for disease or patient specific drug effects. If you can kill ovarian cancer cell-lines with a given drug, it doesn't tell you anything about how the drug will work in real world, clinical ovarian cancer (real-world conditions).

As a general rule, studies from established cell-lines (tumor cells that are cultured and maniplated so that they continue to divide) have proved worthless as models to predict the activity of drugs in cancer.

They are more misleading than helpful. An established cell-line is not reflective of the behavior of the fresh tumor samples (live samples derived from tumors) in primary culture, much less in the patient.

Established cell-lines have been a huge disappointment over the decades, with respect to their ability to correctly model the disease-specific activity of new drugs. What works in cell-lines do not often translate into human beings. You get different results when you test passaged cells compared to primary, fresh tumor.

In regards to tissue samples injured by shipping to a lab, compromising test results, what what cell culture assaysists do is they start with a piece of tumor, chop it into little pieces, digest it with collagenase, which digests the connective tissue strands which may be present.

This releases little microclusters of tumor cells, containing between 5 cells and 500 cells. These little microclusters also contain tiny capillary (endothelial) cells, running throughout the microcluster. Thus, this is "native" tumor and "native" tumor architecture. There is no growth. It is precisely as it existed within the body.

These microclusters are plated into medium on polypropylene, which does not allow them to stick to the bottom and spread out and grow. They remain just as they were (although there is a strong tendency for these microclusters to aggregate, basically grab hold of one another, so the microclusters get bigger, but this is usually not owing to cell growth but rather to cell aggregation).

Anyway, drugs are added immediately, before the cells and cultures have had the chance to change in any way. When the drugs work, they trigger apoptosis and the cells die and they detect cell death 96 hours later.

In regards to some companies offering commercial tests on surgically removed tumors using a small number of anticancer drugs, there are private laboratories that have been offering "cell-death" functional profiling assays as a non-investigational, paid service to cancer patients, in a situation where up to 30 different drugs and combinations are tested, at two drug concentrations in three different assay systems.

Another problem with cell-line technology is that cancer doesn't grow too much, it dies too little. This is why old cell-growth-based assays didn't work and why cell-death-based assays do.

The concern should be in killing the cancer cell. When the cancer cell is so damaged that it can not longer perform its duty, it will die. Scientists know that cancer is not a disease in which cells grow too abundantly, but the failure of cells to expire at their appointed time. Most basic cell biologists acknowledge that cancer is characterized by a failure of programmed cell death (apoptosis).

One way to look at programmed cell death, is with cell-death assays utilizing functional profiling, which use apoptotic endpoints (point of termination) and also a number of other indicators of programmed cell death. The advantage of this is that they are more reflective of chemotherapy’s actual effects in the human body. Genetic testing can’t and doesn’t do this.

Source: Cell Function Analysis

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