As genomic sequencing has become faster and less expensive, physicians have used this new technology to guide and manage care for patients with cancer. Genomic testing, also known as genomic profiling, was initially used for patients with advanced cancer when standard therapy failed. The goal of the testing was to identify unique genetic characteristics of a patient’s tumor that could be targeted with alternative therapies. Now, many more cancer patients have the potential to benefit from genomic testing.  DNA testing, available through what’s known as next generation sequencing technology, is also being used to improve early detection of cancer, assess cancer risk,  monitor  response and detect recurrence.

Mitesh Borad,M.D.

In their paper Twenty-First Century Precision Medicine in Oncology: Genomic Profiling in Patients With Cancer in the October issue of Mayo Clinic Proceedings, authors Mitesh Borad, M.D., at Mayo Clinic, and Patricia LoRusso, D.O., at Yale University, provide an overview of how genomic profiling is being used in many areas of cancer care. They also highlight barriers to successful clinical implementation thus far and outline critical issues that must be addressed in future research efforts in order to advance the use of genomics to guide cancer care.

“Next generation sequencing has already enhanced our understanding of the genetic characteristics underlying cancer. To support use of this promising technology, future research efforts need to build clinical evidence to guide how next generation sequencing can most effectively be used to develop individualized approaches to cancer care,” says Dr. Borad.

Barriers to delivering targeted therapies to patients

For many patients with advanced cancer, clinical trials that include genomic testing offer the hope of finding an individualized treatment targeted at genetic characteristics of their cancer. According to the authors, only a small percentage of patients have benefited thus far from individualized therapies identified in these clinical studies.

The authors suggest that several factors may be contributing to the limited success of delivering targeted therapies using genomic profiling so far:

• Time required consenting patients, obtaining and processing tissue samples and analyzing results.
• Difficulty accessing drugs that are not yet approved to treat a specific type of cancer.
• Stringent patient eligibility requirements in order to gain access to investigational drugs.
• Focus on single-agent therapies that only target one genetic variation linked to the cancer as opposed to looking for treatments that may target all relevant pathways that could be associated with a patient’s cancer.

Critical issues for the next phase of precision cancer care

In order to build the rigorous evidence needed to support the use of genomic testing in clinical care for cancer, the authors suggest that physicians and scientists address these questions in future research:

• Determine the benefit of using genetic panels versus more comprehensive genetic testing methods: Next generation panels, which look at a defined set of genes that may be linked to a specific type of cancer, can generate results in less than two weeks. In contrast, whole exome sequencing, which looks at all known genes associated with disease, may provide a more comprehensive approach to searching for genetic variations linked to a disease or response to a specific therapy. However, it can take several weeks for results from these comprehensive tests.
• Analyze both tumor and normal tissue to guide care decisions: By comparing genomic sequencing results for both normal and tumor tissue, researchers may gain a more accurate picture of genetic variations underlying a patient’s cancer and reduce the number of false-positive genetic findings.
• Analyze multiple tumor samples rather than a single tissue biopsy: Cancers differ in their molecular characteristics. For example, key genetic mutations may differ between tumors in the same patient or even between different samples of the same tumor. Therefore, several tumor samples may give a more accurate picture of a patient’s cancer.
• Take a bigger picture approach to looking at genetic causes of cancer: The authors highlight the importance of using genome-wide analysis to explore all genetic links underlying a patient’s cancer rather than only exploring single gene variations to search for potential treatment targets.
• Data sharing and privacy concerns: The authors highlight the need to share research findings and data across institutions in order to advance the use of genomic testing in cancer care, while also putting systems in place to ensure patient privacy and data security.

Mayo Clinic Proceedings Symposium on Precision Medicine 

This paper is the sixth in Mayo Clinic Proceedings Symposium on Precision Medicine, a series of articles that cover a wide range of topics in personalized medicine. Watch for upcoming articles in the symposium, which will focus on how personalized medicine and genomics are impacting patient care. Learn more about the series.

Join the conversation

For more information on the Mayo Clinic Center for Individualized Medicine, visit our blog, Facebook, LinkedIn or Twitter at @MayoClinicCIM.

See highlights from our recent Individualizing Medicine Conference 2017: Advancing Care Through Genomics:

• #CIMCon17 is underway
• #CIMCon17 continues with the microbiome and more
• #CIMCon17 day two explores how precision medicine can improve population health
• #CIMCon17 - precision-medicine for smoking cessation, rare diseases and cancer screening

Save the date for next year’s Individualizing Medicine Conference. It will be held Sept. 12-13, 2018.

Tags: #cancer treatment, #Dr. Mitesh Borad, #genetic panel tests, #Genomic profiling, #targeted therapies, #tissue biopsy, #tumor sequencing, cancer, center for individualized medicine, Dr. Patricia LoRusso, mayo clinic, Mayo Clinic Proceedings, medical research, Precision Medicine, Research, whole exome sequencing