Scientists watch for a new Lyme disease pathogen and 2 immunotherapy drug trials for myeloma cancelled
Hello and happy Saturday! Here’s our roundup of the week’s interesting and eclectic news in health and medical science.
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A group of U.K. researchers found a natural experiment underway here in Canada in the years following the North American Free Trade Agreement.
Buried deep in the agreement, the team at the University of Oxford discovered a series of tariff reductions on high-fructose corn syrup, a sweetener used in soft drinks and other food processing.
As the tariffs disappeared over a four-year phase-in period ending in 1998, the data showed that Canadians’ exposure to high-fructose corn syrup more than doubled from 21 calories to 63 calories per person per day. That’s an extra 42 calories for every Canadian every day.
‘It doesn’t seem like a lot, but when it comes to gaining weight, small increases can really add up over time’– Pepita Barlow, health economist
“It doesn’t seem like a lot, but when it comes to gaining weight, small increases can really add up over time,” said Pepita Barlow, a health economist and lead author of the study published this week in the CMAJ.
So did we really consume more high-fructose corn syrup after the North American free trade deal? The data can’t confirm that and the researchers don’t make any causal claims. But they suspect it might be true.
“I would say there is strong support for that,” Barlow said, adding that epidemiologists consider the supply of a commodity to be an indication of potential consumption. And during the same period there were increases in obesity rates and diabetes in Canada.
“There’s a very strong indication that NAFTA was probably a factor in increasing the kilocalorie sugar intake of Canadians particularly in relationship to the increased supply of high-fructose corn syrup,” said Ronald Labonté, University of Ottawa professor of epidemiology who wrote an accompanying commentary in the CMAJ.
The research raises an interesting public health question about unintended consequences from free trade agreements. But it’s an area that has not been widely studied, Barlow discovered when she surveyed the scientific literature.
“Everyone looked at it from an economic perspective, or a political perspective, but the wider health and social consequences are poorly understood at this stage.”
“These trade agreements have been negotiated far too much in secret. There hasn’t been sufficient transparency and debate, yet they have these very long time horizon implications,” said Labonté.
FDA halts cancer immunotherapy trial after increase in deaths
Merck announced this week that the U.S. FDA has suspended two of its immunotherapy trials in multiple myeloma patients because of an increase in deaths among people receiving the drug. A third trial has been partially suspended.
Keytruda (pembrolizumab) is part of a new class of drugs that recruit the body’s own immune system to attack cancer. In the suspended trials, the drug was being tried in combination with other immune-boosting drugs to fight the blood cancer.
“It’s sobering how complex the immune system is,” said Dr. Vincent Rajkumar, professor of medicine at the Mayo Clinic in Rochester, Minn. “When you combine two or three of these new immunotherapy type approaches, you are revving up the immune system and so you could get a result which could be lethal.”
“There’s a lot of promise, but it comes with a lot of caution as well.”
Keytruda has been approved for use in a variety of cancers, including some melanoma and lung cancers, in Canada. Merck has other trials underway looking for new uses against additional cancers.
‘Myeloma survival has more than doubled in the last 10 to 15 years. Right now patients can expect to live many many years with the treatments we have’– Dr. Vincent Rajkumar, Mayo Clinic
“The same drugs that work in one cancer really well might not work in another cancer because each cancer is unique and the effects might be totally different,” Rajkumar told CBC Health.
The FDA did not release details about the reasons for the suspension of the studies.
Merck said in a news release that the FDA has determined that the risk of Keytruda plus the combination drugs outweigh any potential benefit for patients with multiple myeloma. The company had already stopped enrolling patients in the studies last month.
“Deaths can happen because the combination worked less well than the control arm. Or the combination was too toxic. We don’t know which,” said Rajkumar.
“These trials have to be done,” he said, adding that there are many other successful new therapies recently approved to treat multiple myeloma.
“It’s been one of the models for cancer drug development, so it’s not a huge disappointment to the myeloma community.”
“Myeloma survival has more than doubled in the last 10 to 15 years. Right now patients can expect to live many many years with the treatments we have.”
Industry payments to doctors not just a Canadian debate
This week a new study in the BMJ Open revealed the extent of pharmaceutical industry spending on wining and dining, and educating, Australia’s doctors.
And one of the authors is uniquely poised to compare the Australian and Canadian doctor-industry landscapes. Two years ago Barbara Mintzes was in Vancouver, studying pharmaceutical policy at UBC. Now she’s at the University of Sydney.
“Canada is an outlier in terms of the lack of transparency, compared with other countries,” she told CBC Health.
Last month some of Canada’s largest pharmaceutical companies voluntarily disclosed payments to doctors, but they did not name names and the data was criticized for being incomplete.
“There is a big trend internationally,” Mintzes said, adding that the U.S. has led the way with its “Sunshine” rule, created under the Affordable Care Act. The law requires every industry payment to a doctor over $10 to be listed on a searchable database.
France and other European countries have put their own disclosure rules in place. Australia has a form of industry self-disclosure with oversight by a public agency.
“It’s made an enormous difference about how much we know about the effects of the influence of this type of funding,” Mintzes said. “When you have hundreds of thousands of doctors, as you have in the U.S. database, you can actually look at those patterns on a larger scale.”
Already research based on the U.S. data have suggested that pharmaceutical industry payments to doctors are associated with changes in prescribing habits.
New tick-borne bacteria causing Lyme disease in North America
It began with six unusual Lyme disease lab tests at the Mayo Clinic in Rochester, Minn. Scientists were taking a closer look at thousands of blood samples from people with suspected Lyme disease collected before 2014. When they found a handful of samples from Wisconsin, North Dakota and Minnesota with distinct genetic features, they announced they’d discovered a new bacteria capable of causing the human disease.
Until then there was only one bacterial species known to cause the tick-borne illness in the U.S. — Borrelia burgdorferi. (although there were reports that some scientists had found earlier evidence of additional Lyme disease pathogens.) The new pathogen — Borrelia mayonii -— causes similar symptoms, including fever, headache, rash in the early stages, and arthritis weeks after exposure. But B. mayonii might also cause nausea and a diffuse rash rather than the distinctive “bulls-eye.”
And now this week scientists at the U.S. Centers for Disease Control published research suggesting that the new pathogen, like B. burgdorferi, takes a period of time for transmission after a tick bite, more than 48 hours.
“Transmission is minimal for the first 24 hours of attachment, rare up to 48 hours but then increases distinctly by 72 hours post attachment,” the scientists concluded, based on studies with mice.
And there’s evidence that the new bacteria has already landed in Canada. Last November the BC Centre for Disease Control reported finding three ticks that seemed to be carrying a bacteria similar to B. mayonii.
Where did the new bacteria come from and how widely has it spread?
“We’re very curious about that,” said Dr. Eleni Galanis, from the BC Centre for Disease Control.
“It could be that it was transported from the U.S. Midwest by a vector like a bird that can carry ticks and dropped off here in B.C. It could be that we have a pocket that’s endemic for this bacterium, but that it’s at very low levels and not causing much disease.”
“We’re on the lookout,” she said “We have evidence that it exists here but currently it is considered to be very rare. We’ve tested over 19,000 ticks and only three were positive.”
So far there have been no human cases reported in Canada.
“We’ll have to keep an eye out for it to see if that rate will change over time, and if so we’ll be able to study it better to ensure that it is similar to Lyme and ensure that we can continue to treat it with the same antibiotics.”