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Pathologists' Group Takes Aim at Improving MDx Through Preanalytical Sample Quality

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NEW YORK (GenomeWeb) – A group of pathologists at the annual College of American Pathologists meeting last week in Las Vegas, Nevada, said the work that they are doing to raise recognition of the need for higher quality patient samples could provide significant benefits for patient care, and lead to more reliable molecular test outcomes.

The pathologists stressed the importance to the accuracy and reliability of molecular testing of developing and following standard practice guidelines and recommendations related to the provision of higher quality preanalytical patient samples.

Preanalytics are the key to the molecular quality of specimens, which in turn determines the data quality of molecular analysis, said Carolyn Compton, chief medical officer of the National Biomarker Development Alliance in Scottsdale, Arizona, during a presentation at CAP16. Little attention is paid to controlling factors that affect patient sample quality before molecular testing is done, she added.

When tissue, blood, or cytology specimens are removed from patients during pre-analysis, there's ample room for error that can impact test accuracy and ultimately the outcome and therapy prescribed for patients.

"These specimens are viable, they are alive, they come off the patient, and until we stabilize them and stop their biological activity, they are reacting to their environment in a multitude of ways, many of which we don't yet understand," Compton said. "But we do have enough scientific data and experience now to know that there are some steps in getting from the patient to analysis in the laboratory — these so-called periods in the preanalytical realm of practice — where we do things to and with specimens that change their molecular composition and quality."

Low-quality specimens that may affect test accuracy are a compelling concern for healthcare, according to the presenting pathologists. As a result, a multi-disciplinary group — the Pre-analytics for Precision Medicine Project Team (PPMPT), which is part of the Personalized Healthcare Committee of CAP — is now working to develop benchmark metrics for control of preanalytical samples used to test for multiple diseases.

"Even though we have strict regulations and an intense focus on the tests we're doing — the people doing the tests, and the environment in which the test is done — we have only one enforced regulation [for testing breast cancer specimens] about guarding the quality of the thing we're testing," Compton said. The PPMPT aims to "alter this for patients to eliminate to the greatest degree possible the 'garbage-in' paradigm to pathology and molecular analysis," she added.

PPMPT, with input from relevant experts and CAP leadership, analyzed scientific literature relevant to the most important preanalytical variables for bio-specimens. Now, the group is employing those findings to develop practice metrics and evidence-based guidance for pathologists. They are developing data-driven procedures for controlling the most critical steps in the collection and handling of specimens that have an undesired impact on the molecular testing of DNA, RNA, and protein, Compton said.

At the CAP meeting Compton presented the top variables affecting patient samples. For tissue samples, time to stabilization — the time it takes from removing the tissue from a patient to when it is stabilized in formalin to stop biological activity — topped the list. This time to stabilization needs to be less than one hour, according to PPMPT.

Other variables include storage conditions and processing methods, which encompass temperature and section thickness of the sample, as well as method of stabilization, which encompass the type of fixative used and the amount of time the sample is in the fixative.

For blood and serum, the most important parameter is time to processing, and other variables include methods of acquisition, stabilization, processing, and storage conditions.

"Advances in molecular biology are coming very rapidly and leading to exciting new diagnostic and novel treatment approaches," David Hicks, director of surgical pathology at the University of Rochester Medical Center, said during the presentation. Hicks, who is a practicing breast pathologist in addition to being a lab director, said that to stay ahead of molecular advances, high-quality human biospecimens are needed for research and clinical work.  

"We really need to put a greater emphasis on developing standardized methods of tissue procurement for diagnosis and molecular testing," he said. "This is a critical issue that must be addressed by biospecimen research. In the future, this will lead to evidence-based guidelines for best practices in surgical pathology laboratories and molecular testing that will help our patients."

In 2008, Hicks worked on a project initiated by the American Society of Clinical Oncology and CAP to develop a guideline to improve the accuracy of immunohistochemical estrogen receptor and progesterone receptor testing for breast cancer patients. The working panel recommended that ER and PgR status be determined on all invasive breast cancers and breast cancer recurrences, but also determined that up to 20 percent of such IHC tests may be inaccurate in part due to variation in preanalytical variables.

Hicks presented information at CAP16 from a tissue acquisition program he participated in that was conducted by the surgical pathology laboratory in collaboration with operating room staff at the University of Rochester Medical Center. Laboratory technicians were contacted as soon as a specimen was made available in the operating room and they were made responsible for collecting the specimen and transporting it to the laboratory. The group reduced the median time to formalin fixation of the patient sample to within the recommended one-hour limit. The group proved the capability, via this method, of being able to achieve specimen fixation within the required time limit. The group team members also learned that when they had conversations with operating room staff about this process and its importance that this always reduced the time to fixation.

Michael Misialek, associate chair of pathology at Newton-Wellesley Hospital in Newton, Massachusetts, emphasized the importance of following recommendations and guidelines for pathologists who operate not only within academic centers, but also in the community outside the academic environment.

"One of the points that we really want to drive home here is that quality starts with us. It's not just something that is allocated to academic centers," he said. "Most cancer care occurs in the community. A community pathologist provides a diagnosis, and the patient often stays in the community for treatment, so it really does matter what we do."

Misialek said that around two-thirds of all laboratory errors occur in the preanalytical phase.

"We can break down pre-analytic error more specifically," Misialek said. "All pathologists should use similar criteria and similar quality metrics to make sure that the right test is ordered, as well as the right specimen. With regard to patient preparation, for example, whether the patient has been fasting may affect the blood sample and biomarkers we are looking at."

Andrew Schade, senior director of the CLIA-certified clinical diagnostics laboratory at Eli Lily and Company, presented information from the perspective of a pharmaceutical company conducting clinical trials and underscored the importance of quality specimens used in diagnostic tests during that process.

"We're in an era when a test will determine whether a patient will get a drug or not," Schade said. "The treating physician assumes the right test is done on the right specimen, and the pathologist assumes that the specimen was handled appropriately."

If samples are not handled appropriately, and patients test negative for estrogen receptors and progesterone receptors because of an analytic issue in the laboratory, that could deprive the patient of a life-changing therapy, he added.

"This is not a hypothetical or academic discussion," Schade said. "From where I sit now in drug development, it is only getting more and more relevant. The future of molecular testing is here. Everything that we have coming through has a molecular test associated with it, and gene expression is more and more becoming a popular area for diagnostics."

PPMPT has established a timeline of activities to pursue its goal of developing practice metrics and making guidelines available to pathologists. It is developing a webinar about preanalytical variables that it expects to launch later this year.

In 2017, the group expects to submit for publication three papers that describe its findings, and create a proposal consisting of checklist questions that are attached to the top five preanalytical issues. They will then submit a request for guideline creation to CAP.

The group's ultimate objective is to drive implementation of metrics and guidance that would enable high-quality biospecimens suitable for molecular analysis of not just cancer, but multiple disease areas, Compton told GenomeWeb in a follow-up interview.