In a new study, researchers have discovered that two new drugs could help treat an aggressive form of breast cancer.
One drug could reach tumors in the brain, which are notoriously tough to treat.
The other could pair a sort of homing device for cancer cells with a payload of chemotherapy that’s released when it reaches its target.
The research was conducted by a team at the Dana-Farber Cancer Institute in Boston and elsewhere.
Previous research has shown that 15% to 20% of breast cancers are HER2-positive.
They have too much of a protein called HER2 on their cell surfaces, driven by an overactive gene that promotes cancer growth.
In the study, the team examined 253 women with this type of breast cancer to test the guided-missile drug, called T-DXd, given as an infusion every three weeks.
These women had tried on average six previous treatments before the experimental drug.
Different doses were tested, and 184 women got what turned out to be the best one.
The team found that among those women, 61% saw their tumors shrink at least 30%. In 6% of them, no signs of cancer were seen in at least two follow-up scans.
Although the new drug was not tested against others, the team says the response rate is three to four times better than what’s usually seen in this situation.
The median time until cancer worsened was 16 months, and to see anything hold such serious cancers at bay for more than a year is exciting.
The new drug has some side effects, including low blood counts, nausea, anemia or fatigue. Some patients developed dangerous lung inflammation.
The team says this is a rare side effect with other drugs for this type of cancer, but it was much more common with the new drug.
Doctors should watch patients closely and give anti-inflammatory medicines if it occurs.
The other drug is called tucatinib. It’s a drug that’s particularly able to get into the brain. In the study, half of the 612 participants had cancer that had spread there.
All were given usual treatments—Herceptin and the chemo drug Xeloda—plus tucatinib or dummy pills.
The team found after two years, 45% of those on tucatinib were alive versus 27% of the others.
Among the women whose cancer had spread to the brain, one quarter was alive with no worsening of those tumors a year later. None of the women in the comparison group achieved that.
Common side effects of the drug include diarrhea, fatigue, nausea, and some liver problems.
The lead author of the study is Dr. Ian Krop.
The study is published in the New England Journal of Medicine.
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