Targeted cancer treatment could replace chemo and radiation in future
Cancer treatments that attack tumors based on their individual genetic traits, and not just their location in the body, could extend survival for twice as many patients, says a new study done by the MD Anderson Cancer Center in Texas.
Targeted therapy involves testing tumours for clues about their genetic mutation, and matching drugs to block the cancer’s growth on a molecular level. Such targeted options have risen dramatically in the last two decades, and offers hope that tumour testing and cell-free DNA analysis may eventually become the standard of care.
A new study by Montefiore Medical Center in New York also showed that women with early-stage breast cancer could safely skip chemotherapy after gene testing without hurting their chances of beating the disease.
“I am optimistic that in the next few years we will dramatically improve the outcomes of patients with cancer with increasing implementation of precision medicine,” said Apostolia Tsimberidou, professor of investigational cancer therapeutics at MD Anderson Cancer Center in Texas and the lead investigator of the study.
What the study shows
Tsimberidou and her colleagues began studying the impact of these therapies in 2007, after seeing the success of Gleevec (imatinib) — a breakthrough drug approved by US regulators in 2001, that showed huge success against leukemia. Their study, titled IMPACT, is the first and largest to look at survival across cancer types and different targeted therapies. More than 3,700 patients at Texas MD Anderson Cancer Center enrolled from 2007 to 2013.
All had advanced cancers, or “end-stage disease” involving cancers of the gastrointestinal tract, breast, or lung. Melanoma and cancer of the female reproductive tract were also included, along with more rare types of cancer. Those enrolled had typically tried at least four — and sometimes up to 16 — other treatments that failed to halt the growth of cancer.
More than 1,300 were found to have tumours with at least one genetic change. Of these, 711 received a treatment that matched the biology of the tumour. Another 596 received a treatment that was not matched, often because no matched treatment for the patient were available at the time. After three years, 15% of people treated with targeted cancer therapies were alive, compared to seven percent in the non-targeted group. After 10 years, six percent of the targeted group was alive, compared to just one percent in the other group.
Far from a cure
On the whole, targeted therapies led to an average of four months of life without the cancer advancing, known as progression-free survival, and nine extra months of overall survival. Those who were treated with traditional approaches lived just under three months without cancer growing, and 7.3 months longer overall.
This method of molecularly profiling tumours, understanding their genetics and how to act on that “is the wave of the future,” said Catherine Diefenbach, an oncologist at New York University (NYU) Langone, who was not involved in the study. For Diefenbach, the study illustrates a paradigm shift in cancer treatment, whereby cancers are no longer treated on the “neighbourhood” of the body in which they arise.
“Prior to precision medicine, patients were treated based on what kind of cancer they had. But a breast cancer patient can have a cell that is much more like a lung cancer patient, genetically, than another breast cancer,” she said.
The field of precision medicine has grown immensely since the study began, said Tsimberidou, recalling that back in 2007, they tested for no more than one to two genes. “Now patients are being tested for hundreds of actionable genes, amplifications and mutations, as well as for immune markers,” she said.
Other novel studies on treating cancer
* A 2015 trial at the National Institutes of Health Clinical Center offered the first evidence that immunotherapy, which has already seen some success in blood cancers and melanoma, could work against cervical cancer.
* Scientists at the University of Delaware have developed a two-way process to kill liver cancer cells and inhibit tumour growth. At first, they silenced a key cellular enzyme, and then they added a powerful drug.This research could accelerate the development of new treatments for liver cancer, which is currently difficult to cure.
* According to a study conducted by the University of East Anglia, cancer therapies that cut off blood supply to a tumour could be more effective in combination with existing chemotherapeutic drugs.
* A study led by The University of Texas MD Anderson Cancer Centre found that a drug has potential as a new therapeutic strategy for bone cancer.
(With inputs from AFP)
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