Genomics and Gene-Editing Techniques Promise Hope for Cancer Treatment
Research into the genetics of cancer has created major shifts in the way both physicians and patients think of the disease. With the advent of genetic testing, there is an opportunity to discuss preventive measures for those at risk. Genomics are also revolutionizing treatment options, and new techniques, such as gene-editing, may open new possibilities. The opportunities to help your patients are only expanding.
"In oncology in the past, treatments were developed by the kind of cancer, meaning what tissue it originated in," says Dr. Michael Alexander, medical director of oncology at Dignity Health Dominican Hospital in Santa Cruz, California. "To a certain extent, we are moving away from treating cancer by where it came from, and focusing instead on the genetic and other cell-marker abnormalities that are present."
When Is Genetic Testing Routine?
Inherited cancer syndromes typically have an associated genetic abnormality, and researchers and providers have a good understanding of some of the most common mutations. For example, hereditary nonpolyposis colorectal cancer (HNPCC) is a genetic condition that carries a high risk for colon cancer, as well as endometrial, stomach, urinary tract, and other cancers. Sometimes treatment options are available that target these genetic abnormalities and can offer an alternative to (or work in combination with) chemotherapy.
Staying abreast of current research in genomics is vital to the current practice of oncology. "You have to learn as you go," Dr. Alexander says. "We weren't talking about this when I was in medical school, but it is critical for oncology care."
Dominican Hospital recently began routinely screening all colorectal and uterine cancers for these abnormal genes to guide treatment and follow-up. They can also offer genetic counseling services to a patient's family members, who may also be at increased risk. Dr. Alexander says that previously, patients would be recommended for genetic screening based on family history, age, and presentation, such as cancer on the right-hand side of the colon. However, studies showed that that approach overlooked many patients with genetic abnormalities. Routine screening has become standard at many major academic centers, as well.
Targeted Therapies Work Against Genetic Mutations
Targeted therapies for a range of diseases are being heavily researched, and they could lead to major changes in your practice as they are introduced. Targeted therapies are proven to treat lung cancer, for example, and treatment recommendations may change based on genetic screening. Some lung cancers have mutations in the EGFR or ALK genes and can be treated with drugs that block EGFR or the ALK protein, according to the American Cancer Society. These therapies may be used in conjunction with chemotherapy or on their own, and sometimes they can work when chemo fails.
One new trial is beginning that will direct patients with lung cancer to one of five experimental therapies based on the genomic profile of their tumor. The trial is also designed to be flexible, opening up other treatment arms as new research is available.
Providers have an understanding of the mutations involved in many different cancers, but there's still a ways to go before targeted treatments are widespread. In fact, targeted treatments are not always available, even for cancers for which the mutation is understood. "Some targeted therapies are for fairly uncommon diseases," Dr. Alexander says. "Some mutations that have treatments are only present in about 10 percent or less of patients."
In other cases, targeted therapies have yet to be developed for well-known mutations. Mutations in the BRCA1 and BRCA2 genes are associated with most inherited breast and ovarian cancers, along with some other cancers, but the development of successful targeted therapies has proven challenging so far.
Gene Editing and the Future of Genomics Research
Further targeting of genetic abnormalities can be done with gene therapy and gene-editing techniques. Gene therapy targets the cells that need repair to interfere with the expression of proteins or to correct genetic mutations. This is usually done through the use of nucleic acid polymers. According to the New York Times, the first gene therapy drug was approved in Europe in 2012. The drug, Glybera, provides correct copies of the lipoprotein lipase gene to treat deficiency disorder. Although a gene therapy to treat cancer has not been approved yet, there have been successes in testing.
Studies are also underway that experiment with gene-editing techniques. The CRISPR-Cas9 method for gene editing is gaining the most popularity for its ease of use, although research is currently limited to mice and in the laboratory. According to ScienceDaily, the system uses the Cas9 enzyme, which cuts DNA, combined with a guide RNA to bind to specific genome sites. Researchers have the potential to turn genes on and off and study the effects of different targeted treatments.
Genomics research has taken off in the past decade, with new technologies constantly being developed, and targeted therapies are being designed in many laboratories. That means cancer care is moving into an era of truly personalized medicine with the potential for many new treatment options.
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*This information is for educational purposes only and does not constitute health care advice. You should always seek the advice of your doctor or physician before making health care decisions.