Can CDK4/6 Inhibitors Help Prevent Breast Cancer Recurrence?
- For women with a common subtype of breast cancer, hormone-receptor-positive and HER2-negative (HR+ and HER2-), a newer class of medicines called CDK4/6 inhibitors are showing promise.
- CDK4/6 inhibitors work to interrupt the growth of cancer cells.
- Data from a clinical trial called NATALEE found that patients with this specific type of breast cancer who received a CDK4/6 inhibitor called Ribociclib (sold under brand names Kisqali and Kryxana), plus endocrine therapy, had a 25% lower risk of recurrence or death.
- Dr. Eleonora Teplinsky, Head of Breast Medical Oncology at Valley Health System, told SurvivorNet that it’s important for patients to sit down with their doctors and have a candid discussion about side effects to determine if using a CDK4/6 inhibitor like Ribociclib is worth the potential benefit.
CDK4/6 inhibitors work to interrupt the growth of cancer cells. SurvivorNet sat down with Dr. Eleonora Teplinsky, Head of Breast Medical Oncology at Valley Health System, to discuss how a CDK4/6 inhibitor, Ribociclib (sold under brand names Kisqali and Kryxana), is being studied for women with this specific type of breast cancer.Read More
“In the group that received Ribociclib and endocrine therapy … at three years their disease-free survival was 90.4% compared to 87.1% in the group that received endocrine therapy alone,” Dr. Teplinsky said. This translates to a 3.3% “absolute improvement.”
It’s important to note that this therapy option is not currently FDA-approved.
How Does the CDK4/6 Inhibitor Work?
CDK4/6 inhibitors assist in slowing down cancer growth in women with HR+, HER2- breast cancer.
Generally speaking, CDK4/CDK6 inhibitors are targeted therapies that fight off proteins known as the cyclin-dependent kinases 4 and 6 (CDK4/CDK6).
These proteins control how fast cells divide and multiply, and for women with breast cancer, these proteins can cause cancer cells to grow uncontrollably. That’s how CDK4/CDK6 inhibitors can help they slow down or prevent the proteins from multiplying.
Dr. Teplinsky stressed that doctors and patients should work together and have a candid discussion about side effects to determine if using a CDK4/6 inhibitor like Ribociclib is worth it.
“This all depends on the disease characteristics. Let’s say someone is lymph node-negative and they have a tumor size of three centimeters. They, based on this study, would be eligible to receive Ribociclib,” she explained. “…How do we make that decision and how do we have that conversation in the office about the risks and the benefits?
“We know there’s a 25% lower risk of recurrence. That’s great, but we also have to balance some of the side effects.”
She continued, “I think it’s a really hard decision for someone whose risk is a little bit lower to begin with, compared to someone who has a higher risk of recurrence. And how you navigate that is really going to be an individual conversation between patient and doctor and balancing all of those side effects with the benefit.”
Understanding Risk vs. Benefits
Dr. Teplinsky explained that it’s important for patients to understand the difference between “relative risk and absolute risk.”
While there was a 25% lower chance of cancer coming back among the population that did take Ribociclib in the NATALEE trial, “that translates into a 3.3% absolute risk,” she explained. “When you look at the numbers, 87.1% of patients who did not recieve Ribociclib did not experience a recurrence compared to 90.4% of patients who did receive Ribociclib and did not experience a recurrence.”
She continued, “I think the challenge if you were a patient and trying to figure this out is, how do you know if you would fall into that 3.3%? And, and we don’t know.”
Dr. Teplinsky is prepared to speak with her patients about the new medication available for them as she sees the benefit in making her “patients partners in their healthcare and having them be their own health advocates.”
Common possible side effects of Ribociclib include:
- Neutropenia, which is a low count of a type of white blood cell called neutrophils, which helps fight certain infections
- Leukopenia, which is a low white blood cell count
- Alopecia, a type of hair loss
Dr. Teplinsky also notes that adverse effects include lung disease and elevated liver enzymes, which can indicate the liver is inflamed or damaged.
“I think it’s really important to say, ‘Look, we have this new medication, here are the benefits, here are the side effects,” Dr. Teplinsky added.
“Then really work through each individual patient about whether it’s something that is going to be right for them.”