Recent studies show some promise in understanding chemo-caused neuropathy, and perhaps in using a common medicine to ease the worst symptoms in some people.
Study shows neuropathy relief for some using antidepressant
A well-designed clinical study has provided the first evidence that the antidepressant Cymbalta® (duloxetine) can provide some patients with significant relief from peripheral neuropathy caused by chemotherapy.
From 20 to 40 percent of cancer patients given neurotoxic chemotherapy–taxanes, platinum-based including Eloxatin® (oxaliplatin), vinca alkaloids, bortezomib–will develop painful peripheral neuropathy (numbness, tingling, burning in hands or feet). If the pain is severe, colorectal cancer patients often have to reduce the dose or stop taking Eloxatin. Even then, this painful condition can persist for months, even years, after chemotherapy is stopped.
Previous studies have found that Cymbalta eases the neuropathy pain caused by diabetes, but this is the first comprehensive trial testing whether Cymbalta could ease neuropathy from chemotherapy. As reported in the April 3, 2013 JAMA (Journal of the American Medical Association), the trial enrolled 220 patients at 8 different cancer centers across the U.S. who still had significant neuropathy (at least 4 on a pain scale of 10) at least 3 months after chemotherapy. (Over half, 129 patients, had taken Eloxatin, mostly for colorectal cancer.) In this randomized, double-blind (neither patients nor clinicians know who’s getting the test drug), crossover trial, one-half the group received Cymbalta for 5 weeks while the others took a placebo, and then the groups switched treatments.
Of those taking Cymbalta, 59% reported at least moderately decreased pain (minimum 1 point on the 10-point scale)—usually within the first week. Among those taking a placebo first, 38% reported decreased relief. Interestingly, Cymbalta-associated pain relief was significant only in feet, not hand, symptoms. Also, 11% of people taking Cymbalta had to stop due to side effects—mostly severe fatigue.
Experts theorize that the antidepressant might help because it reduces the neurotransmitters serotonin and noradrenaline, which deliver pain messages to the brain. The study authors pointed out limitations in this first study: relatively small numbers, the effects measured by patient self-report, and the study only followed patients for 5 weeks on Cymbalta.
However, “This is not just about improving quality of life by decreasing pain, but potentially it’s helping patients live longer because they can get their full chemotherapy treatment,” noted lead author Ellen M. Lavoie Smith, Ph.D., APRN, AOCN, of the University of Michigan Comprehensive Cancer Center.
Another expert not connected to the study, Marie Bakitas, D.NSc., at the University of Alabama at Birmingham School of Nursing, noted that the trial results weren’t surprising, because duloxetine is already being used in clinics. But, she also told Medscape, other treatments such as physical therapy, acupuncture and massage “are often neglected but can be very useful.”
Sources: “Effect of Duloxetine on Pain, Function, and Quality of Life Among Patients With Chemotherapy-Induced Painful Peripheral Neuropathy,” April 3 JAMA Network; “Drug for Depression Mutes Chemo Nerve Pain,”April 2 Medscape; “Antidepressant helps relieve pain from chemotherapy, study finds,” April 2 Univ. of Michigan Health Systems press release.
Searching for genes that could predict peripheral neuropathy
Mayo Clinic researchers have reported that they’ve found that patients with mutations in three specific genes were more likely to suffer peripheral neuropathy from chemotherapy.
Currently, doctors have no way to predict who will have the side effect, how severe it will get, nor how long it will last.
At the recent meeting of worldwide cancer researchers (AACR, or American Association of Cancer Researchers), scientists described how they studied more than 20,000 specific genes in 119 patients—over half of whom had developed peripheral neuropathy during chemotherapy. They pinpointed three genes, in which mutations were clearly associated with developing neuropathy. Their next step will be to expand their study of the entire genome in as many as 1000 patients. The ultimate goal would be to use these types of genetic clues to potentially predict which patients might suffer side effects from specific drugs.
Fight Colorectal Cancer’s Board Chair Nancy Roach noted that these first findings are a long way from proving cause-and-effect, creating a test, and actually being able to get a reliable test to doctors and patients.
Disclosure: Fight Colorectal Cancer has accepted funding from Sanofi, manufacturer of Eloxatin, in support of its programs. Fight Colorectal Cancer has ultimate authority over website content.