GRADE is trying to find out if there is a link between a hormone called GDF-15 and the side effects that people can experience when taking T-DXd.
GDF-15 can be measured in the blood. GDF-15 levels in the blood will go up when the body is stressed under certain conditions, including breast cancer. There is a link between high GDF-15 levels and the nausea and vomiting experienced with "morning sickness" in pregnancy. It has also been shown that GDF-15 levels will go up with the use of other types of chemotherapy that are known to cause nausea and vomiting.
Side effects such as feeling sick (nausea), vomiting and weight loss are common with T-DXd. Sometimes, these can be so severe that treatment needs to be stopped early. The investigators can't predict who will get bad side effects and who will not.
If the investigators can find out if there is a link between GDF-15 and the side effects of T-DXd, they can use this information in future clinical trials.