Blog | Tuesday, March 13, 2012

A glitch on the road to personalized oncology


We receive a quarterly magazine in the office called CURE, which stands for Cancer Updates, Research & Education. Browsing through the Winter 2011 issue, I noticed a short article entitled "Lacks' Legacy" with an accompanying picture of Henrietta Lacks.

I've previously published a blog on HeLa cells, the cell line cultured from her original cervical cancer. These cells are immortal in that they contain an enzyme at the tips of their chromosomes which prevents them from undergoing programmed cell death ("apoptosis"). "Lacks' tissue has since spawned an estimated 50 metric tons of HeLa cells, and the total number of HeLa-related medical studies-roughly 60,000 to date-is growing by about 300 per month." These cells were so malignant they were able to rapidly proliferate despite primitive tissue culture procedures.

It then occurred to me that the article was actually a sidebar to another piece called "Why Banks Need Your Tissue for Research" by Paul Engstrom, about tissue repositories. One major message is the wide gap that exists between knowledge generated in the laboratory (meaning biomarkers and targets for new therapies) and biobanking.

A partial list of problems includes "inconsistent collection, processing and storage of tissue, which can alter its molecular composition and skew experimental outcomes; shortages of high-quality tissue; outdated preservation techniques; the high cost of and inadequate funding for repositories; patients' lack of awareness about tissue donation; and, for competitive and other reasons, institutions' hoarding specimens they might otherwise share with researchers elsewhere."

These are major issues. Since it is becoming a standard practice in clinical trials to collect, store and study tissue, then maintain these specimens for future investigations, addressing these concerns is essential. The recently completed TAILORx study of 10,000 newly diagnosed women with early stage, hormone receptor positive, node negative breast cancer is a good example.

The Oncotype DX Assay to identify patients who might benefit from the addition of adjuvant chemotherapy to hormonal therapy as opposed to those who won't was obtained from archived tissue specimens. It is therefore vital that all efforts are made to assure that all institutions supplying these tissues and the repositories processing and storing them follow standardized procedures to validate that results are accurate.

All of this sounded familiar to me. Then, I remembered an article I'd read previously in one of my favorite medical journals, WIRED magazine, entitled "The FLESH FILES" by Steve Silberman, June, 2010, pg. 156. This is when I first became aware of the extent of these problems.

In 2005, the NCI announced the plan to create the Cancer Genome Atlas using the same techniques employed to delineate the human genome-high-throughput DNA sequencing, lab automation and computational biology. The pilot phase would catalog genetic mutations in three of the major cancer killers: glioblastoma multiforme (the most malignant brain tumor), serous cancers of the ovaries, and squamous-cell lung cancers.

This Atlas could reveal new tests, like the Oncotype Dx test, that would help determine treatment, develop novel agents directed against these mutations, and new methods to detect these cancers at an earlier stage. Unfortunately, the Atlas was put on hold not because of difficulty with scientific techniques, but due to lack of viable tissue specimens to test. In short, the biobanking system was in shambles.

Reasons for the sorry state of tissue repositories are numerous. Focusing in on one aspect, freezing and thawing of tissues, classical solutions used to cryopreserve cells and bodily fluids are glycerol and dimethyl sulfoxide (DMSO).

Tissue requires a different preservation method, using two relics from the Victorian era: formaldehyde (in a diluted form called formalin) and paraffin. Formalin acts as a fixative, arresting all cellular metabolic processes, while paraffin prevents oxidation. Under the microscope, these substances preserve cellular structure. But they play havoc with genetic material inside cells.

"Some cells get so stressed that hours after they thaw, they take themselves out of the gene pool permanently" by undergoing apoptosis, the same "programmed cell death" that is not seen in the immortalized HeLa cells. Even cells that don't die experience genetic changes in the freeze-thaw cycle that can lead to an overestimation of the quality of biospecimens. The result is corruption of the genomic data.

Additionally, formalin causes significant alterations to cellular RNA, a major probe used to decode the genetic mechanisms of cancer. And DMSO can actually accentuate the metastatic potential of a cancer. If infused into patients, DMSO can result in chills, nausea, kidney failure and cardiac arrest, especially in children. Use of DMSO can be reduced by "chilling tissue at a carefully controlled rate immediately after harvesting (using a technique appropriated from Eskimos in the early 1900s by Clarence Birdseye, father of the frozen-food industry)." But, adoption of this procedure would disrupt the routine of already overworked hospital staff.

Enter Carolyn Compton, M.D., PhD, director of the Office of Biorepositories and Biospecimen Research at the National Cancer Institute (NCI) in Bethesda, Md. She is spearheading the effort to establish a central, public-private cancer tissue repository called the Cancer Human Bank (caHUB). Unfortunately, these plans are on hold due to lack of sufficient federal funds. Instead, $23.5 million in federal stimulus funds will be used by the NCI to expand research on standards for collecting, processing, storing and disseminating tissue specimens.

This post by Richard Just, MD, ACP Member, originally appeared at JustOncology.com, a joint publication of Richard Just, MD, aka @chemosabe1 on Twitter and Gregg Masters, MPH, aka @2healthguru on Twitter. Dr. Just has 36 years in clinical practice of hematology and medical oncology.