|Scientists working on breast cancer treatment said they've made "exciting" advancements in developing two new drugs tested in separate trials / Photo by: Viacheslav Lopatin via Shutterstock|
Scientists working on breast cancer treatment said they've made "exciting" advancements in developing two new drugs tested in separate trials.
Senior author Eric Winer, a professor of medicine at Harvard Medical School, said the exciting part about the developments is that the most dramatic changes occur among people with HER2-positive breast cancer.
"It is the single area in breast cancer where we have made the most dramatic progress and continue to," he told CNN. "For individuals with advanced breast cancer, we can individualize therapy more than in the past. It is no longer one size fits all."
Improving Survival With Tucatinib
HER2-positive breast cancer is a type of cancer positive for higher HER2 protein, which promotes the growth of cancer cells, and 15-20% of breast cancer patients have cells positive for this protein.
Some drugs can directly target the HER2 protein, allowing up to 10 years of survival for 80% of HER2-positive patients. However, Forbes says treatments still don't work on many people and cause cancer to spread further.
Addressing this concern means coming up with new treatment options. One of the promising treatments is a new drug called tucatinib, which targets HER2-positive cells. In a global trial, researchers used tucatinib with a chemotherapy regimen consisting of trastuzumab and capecitabine for half of the 613 patients in the study while the other half received a placebo.
In the tucatinib group, 45% were alive two years following the treatment compared to the 27% of patients who didn't receive the drug in their regimen.
Forbes notes a "particularly interesting" finding in showing a 52% reduced risk of progression or death in patients with brain metastases—in which cancer has spread to the brain—and was on the tucatinib treatment combination.
The new drug is also considered "well-tolerated" in penetrating the brain tissue compared to other agents. This is evident in the small percentage of patients (5.7%) who discontinued their tucatinib combination treatment due to toxicity.
"As with all therapy, resistance to tucatinib does develop over time. There may be biomarkers that identify patients who derive a particularly large benefit from the drug," said Winer, who is also the senior author of the tucatinib study published in the New England Journal of Medicine.
"There is also interest in combining tucatinib with other novel agents to improve efficacy," he added, noting that he believes the US Food and Drug Administration (FDA) will approve the drug sometime next year.
|Addressing this concern means coming up with new treatment options. One of the promising treatments is a new drug called tucatinib, which targets HER2-positive cells / Photo by: lovelyday12 via Shutterstock|
Reducing Tumor Activity
The other study, also published in the New England Journal of Medicine, involved 184 HER2-positive breast cancer patients who have undergone multiple treatments. Researchers gave the recommended dose of an antibody-drug-conjugate treatment known as trastuzumab deruxtecan (T-DXd) of 5.4 mg per kilogram of body weight.
T-DXd attaches itself to cancer cells (in this case, to the HER2 protein) and delivers a payload of chemotherapy, which then stops DNA replication and halts the division of cancer cells.
The treatment effectively shrunk cancer by at least 50% for 60.9% of the patients, in spite of side effects such as nausea, interstitial lung disease, and myelosuppression or the decline in bone marrow activity. Still, CNN reports that some of the patients saw no further progression of their cancer for a median of 16.4 months.
These findings are "striking," said Ian Krop, a principal investigator of the study and associate chief of the division of breast oncology at Dana-Farber Cancer Institute in Boston.
"These results are particularly striking as trastuzumab deruxtecan prompted a high level of durable tumor reduction among patients, the majority of whom had exhausted most if not all standard therapies for HER2-metastatic breast cancer," he explained.
Krop added they are excited with the results and their potential to help patients who are in the advanced stage of breast cancer.
Meanwhile, Oncology professor Otis Brawley said it's rare for a drug to cause effects on women who are "heavily pretreated."
"I am cautiously optimistic," Brawley, who was not involved in the study, said but noted that additional work is needed to determine if T-DXd can improve patient survival.
These developments could not come at a better time than now, given the urgent need for innovation in treating HER2-positive breast cancer. They may also become available soon.
Biotechnology company Seattle Genetics is planning to submit a new drug application to the FDA and the European Medicines Agency for tucatinib as they aim to bring the new drug to the public, Roger Dansey, chief medical officer at the company, said in a statement.
Meanwhile, the FDA has already granted priority review for the T-DXd in October after demonstrating promising results in an initial trial of patients with advanced HER2-positive breast cancer.
The researchers believe approval is possible for the T-DXd despite the side effects, which they said were "mild and manageable."
"Given the unique ability of this drug to control cancers in a high percentage of patients whose cancer had already developed resistance to other therapies, I don’t think the drug’s potential side effects will be a barrier to approval," said Krop, adding that they would still have to work on minimizing the drug's toxicities.