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Massachusetts, US (BBN) - Cancer is a disease that afflicts particular organs. That is why there are lung cancers and blood cancers and, under the influence of genetics, an organ serves as an epicentre from where it could radiate and consume a person.
This constitutes the classical view and influences treatment strategy today, reports The Hindu.
In 2014, a study published in the International Journal of Cancer found an intriguing link among cancers. The researchers sourced genetic data —from 14 major cancer entities and 4,796 cases available through The Cancer Genome Atlas (TCGA) — based on all available genes as well as different cancer-related gene sets.
The researchers found that in about 43% of the cases, on average, tumours of a particular anatomic site are genetically more similar to tumours from different organs and tissues (trans-similarity) than to tumours of the same origin (self-similarity).
These similarities existed not only for carcinomas from different sites but are also present among neoplasms (an abnormal mass of cells that may or may not be cancerous) from a different tissue origin such as melanoma, acute myeloid leukaemia, and glioblastoma.
“The current World Health Organisation cancer classification is therefore reflected on the genetic level by only about 57% of the tumours,” they report in their study.
NEW APPROACH TO TESTS
In the last three years, the approach that cancer is a genetic disease and not one specific to localised tissues and organs is percolating to therapy. For instance, pembrolizumab was a drug specifically approved only for metastatic melanoma.
This May, the United States Food and Drug Administration (FDA) cleared the drug, marketed by Merck as Keytruda, for use in any kind of solid tumour that resulted due to mutations that affect the DNA’s ability to perform a function called mismatch repair. This is a system whereby DNA can check for errors during the cell-division process.
This approval marked the first instance in which the FDA approved marketing of a drug based only on the presence of specific genetic mutations in a person, irrespective of whether it was a skin or a colorectal cancer. Several more have followed suit. Consequently, several major drug companies are now working on being able to design tests that link a person’s cancer to their genetic make-up in the hope that they could avoid drugs that wouldn’t work or be able to sign for clinical trials that were testing new therapies.
BETTING ON GENETIC PROFILING
For instance, Foundation Medicine (FM), a company in Cambridge, Massachusetts, has just launched a diagnostic test for “personalised cancer care”.
This means that physicians can order in a test that looks for genetic alterations in 324 genes known to drive cancer growth, and identify patients with advanced cancer who are likely to benefit from targeted therapies. FM, in which Swiss health-care major Roche has a majority stake, is betting that genetic profiling will become a critical part of cancer care. “Going ahead, cancer will be seen as a treatable, chronic disease that can be managed with specific therapies,” says Steve Kafka, Chief Operating Officer, FM.
“Even in the United States, only 1% of those who need genomic profiling are getting it.”
FM’s tests build on a knowledge base of over 160,000 clinical cases. Though they aren’t yet available in India, representatives say that those, especially in advanced stages of the disease, could still avail of them. “We are in the process of talking to physicians and doctors in India about the potential of these tests,” says Josh Lauer, Lifecycle Leader, FM. However, a key drawback in India is the lack of access to clinical trials, all of which are located internationally, to addressing particular cancers.
Other experts say that the approach to cancer is significantly determined by where patients are located — a developing country in India or the United States — or more mundanely, the type of cancer in question.
“The genetic approach exists but the location of the cancer tells a surgeon whether it can be cut away or not. Most doctors anywhere would, as far as possible, like to reduce the size of the tumour,” says Anurag Agrawal, Director, Institute of Genomics and Integrative Biology, “At the other end, there are cutting edge treatments like CAR T cells that engineer people’s immune cells to fight. Cost: Half a million dollars.
BBN/MMI/ANS