By Brenda Goodman, CNN
(CNN) — Researchers recently tried an experiment: Gather people who had the same kind of lung cancer and put them on the same type of treatments to fire up their immune systems. The only difference was that half the group got their medications earlier in the day, before 3 p.m., and the other half got them later.
The surprise finding was that the time of day made a difference: Patients who got their first rounds of treatments in the morning had, on average, about five more months before their cancers grew and spread, a measure doctors call progression-free survival — and they lived almost a year longer than those who got their treatments later. They also had better odds of being alive at the end of the study, which has been running for more than two years.
Researchers have long studied the body’s clock, its circadian rhythm, which governs a host of biological functions including the release of hormones, when we feel hungry or tired, body temperature, blood sugar and blood pressure. There are dozens, if not hundreds, of smaller clocks under the control of this master clock at work in cells and tissues.
More recently, scientists who study these body clocks have discovered that the immune system seems to be exquisitely sensitive to timing.
Evidence is mounting that timing may influence how protective vaccines are and the odds of an adverse events after heart surgery. One study found that valve replacement surgery was less risky for patients when it was performed in the afternoon, for example.
The new study, led by researchers in China, was the first to test something that other groups had documented in observational studies. Previous research that looked back at when melanoma and kidney cancer patients received their treatments had reached strikingly similar conclusions: Cancer patients appeared to get far more benefit from immunotherapy drugs when they get them earlier in the day.
Although many experts are excited about the new findings, they’re approaching with caution.
The results are “exceptionally compelling,” said Dr. Zach Buchwald, an oncologist at Emory University’s Winship Cancer Institute who was not involved in the research. “If this were a new drug, they would be hailed far and wide as having discovered something revolutionary.”
But there are questions about why the time of day would be so impactful when immunotherapies are active in the body for weeks after they’re given through IV infusion. The study authors say it’s a valid question and one they can’t answer yet.
“This is possibly the most controversial finding in immune-oncology,” Dr. Paolo Tarantino, a breast medical oncologist at Dana-Farber Cancer Institute and Harvard Medical School in Boston, posted on X. “The effect size is hard to believe. Though [randomized-controlled trials] are hard NOT to believe. We need a coordinated effort … to investigate this.”
The study’s authors want that to happen, too.
“It’s really dramatic that we se