The body doesn't process drugs in the same way throughout the day

It’s news to no one that your body works differently when you’re awake and when you’re sleeping. But could the different states also affect how your body processes certain life-saving drugs? Researchers, reporting Friday in the journal Nature Communications, found that when it comes to cancer drugs, the answer may be yes.
Researchers at the Weizmann Institute of Science discovered—by happy accident—that some of the body’s molecular functions during the day may interfere with the effectiveness of certain cancer medication. Specifically, they found that the normal day-time production of some steroid hormones in the body actually inhibited the work of epidermal growth factor (EGF) receptors—which are the proteins targeted by a class of anti-cancer drugs. Tumor cells plant these receptors on their surfaces to attract nutrients that help them survive and grow. Drugs, including the breast cancer agent lapatinib, can block these receptors on tumors, and such medications are a popular way to treat breast cancers expressing epidermal growth factor.
But Yosef Yarden, a professor in the department of biological regulation, and his team found that when the tumor cells simultaneously bind to something else—such as steroid hormones—the EGF receptors are less active, making drugs like lapatinib less potent.
The findings are still preliminary, but there is other evidence that the day-night cycle may be a potentially important factor in determining cancer treatment dosing in coming years. Some studies showed, for example, that when the 24-hour rest and activity cycle is broken metabolically, and the EGF receptors aren’t given enough time to be active, certain tumors in animals grow two to three times faster.