Major Advancement for HR+, HER2- Advanced Breast Cancer
- New research indicates that a drug called Inavolisib is effective at treating a type of metastatic breast cancer with a common mutation known as PIK3CA.
- This is great news as about 40% of women who have hormone receptor-positive metastatic breast cancers have the PIK3CA mutation.
- Research indicates adding the drug to the treatment plan can double the time women go without their cancer progressing.
- Participants also reported better quality of life and less cancer-related pain.
- “We went from 7.3 months to 15 months, so that’s more than doubling of that time without disease progression,” Dr. Dejan Juric, Medical Oncologist at Mass General Cancer Center, and Assistant Professor of Medicine at Harvard Medical School, told SurvivorNet. “…We also saw that patients have less pain and actually the deterioration in those parameters [are better].”
This is great news as about 40% of women who have hormone receptor-positive metastatic breast cancers have the PIK3CA mutation — and research indicates adding the drug to the treatment plan can double the time women go without their cancer progressing.
Read MoreBreast cancer treatment has seen significant advancements in recent years with the introduction of innovative therapies — and Inavolisib has emerged as a key contributor in this evolution. Inavolisib works by blocking the activity of the PI3K protein. Research shows that blocking this protein can stop the growth of cancer.
What Did the Study Find?
The research presented at the ASCO conference demonstrated that the use of Inavolisib improved overall survival and progression-free survival (the time a patient lives without their disease getting worse) in patients with this type of metastatic breast cancer.
People who took inavolisib went more than twice as long without cancer growth or spread than those who did not (15 months versus 7.3 months). These patients also experienced less cancer-related pain for over a year and were generally less bothered by the treatment. Most people said the side effects bothered them “not at all” or “just a little” during the past week.
Because of these incredible findings, the U.S. Food and Drug Administration (FDA) has granted breakthrough therapy designation to Inavolisib for the treatment of patients with this specific subtype of locally advanced or metastatic breast cancer. This new drug is expected to be approved in November 2024.
Understanding Metastatic Breast Cancer
Metastatic breast cancer, also known as stage IV breast cancer, is when cancer has spread beyond the breast to other parts of the body such as the bones, liver, lungs, or brain.
It’s considered an advanced stage of cancer and requires different treatments than early-stage breast cancer. This diagnosis can feel overwhelming, but it’s important to know that many people continue to live fulfilling lives while managing their cancer.
Breaking Down the Data
The INAVO120 phase III clinical trial demonstrated that patients taking Inavolisib experienced a significant delay in cancer progression — 15 months compared to 7.3 months for those not taking the drug. Phase III trials are the most important piece of scientific evidence as they test innovative new drugs at a larger scale than previous studies.
It’s important to say that this new drug (Inavolisib) was used alongside fulvestrant and palbociclib:
- Fulvestrant (brand name Faslodex) is hormone therapy commonly given to postmenopausal women.
- Palbociclib (brand name Ibrance) was the first CDK 4/6 inhibitor approved by the FDA to treat breast cancer.
In combination, these two drugs are a common first treatment for advanced or metastatic hormone receptor-positive, HER2-negative breast cancer.
Now, researchers have looked at the three-drug combination (inavolisib, fulvestrant, and palbociclib) for cancers that had spread on hormone therapy alone. All three drugs were given at full dose.
- Inavolisib and palbociclib are given as pills you can take at home.
- Fulvestrant is a shot to a muscle in the buttocks and is given in a doctor’s office.
“For first time we are combining three different drugs that are important in metastatic breast cancer. We are using a PI3K inhibitor called Inavolisib, CDK 4/6 inhibitor called Palbociclib and an estrogen receptor targeting drug called Fulvestrant.”
“And why is this important? Because these three targets work together, it’s almost like a triangle that through interactions of these drugs, guides the behavior of cancer cells. So instead of playing a whack-a-mole where you’re trying to just go after one target and the other, we decided to hit all three targets.”
“And when we do that and compare it with just standard therapy, which consists of Fulvestrant and Palbociclib (just two drugs), we see dramatic improvement in what we call progression-free survival. That is the duration, that the patient is on the treatment without progressive disease,” added Dr Juric.
This study involved 325 participants with hormone receptor-positive (HR+), HER2-negative locally advanced or metastatic breast cancer.
What is HR+ Breast Cancer?
Hormone receptors are proteins found on breast cells that pick up either estrogen or progesterone signals and promote cell growth. If the cancer has one of those receptors, meaning it is hormone receptor-positive (HR+), the hormones help the cancer to grow.
Breast tumors may be positive for estrogen receptors (ER+), progesterone receptors (PR+) or both (ER/PR+). About 80% of all HR+ breast cancers are ER+ or ER/PR+, according to Penn Medicine.
HER2 in Breast Cancer
HER2 stands for human epidermal growth factor receptor 2. It’s a protein that can be found on the surface of breast cancer cells and make them grow quickly.
Tumors can be HER-negative, meaning they show minimal or no expression of the protein.
Tumors can also be HER2-low or HER2-positive, depending on the level of the protein present. They respond well to treatments that target the HER2 protein, such as Enhrtu (trastuzumab deruxtecan) or Herceptin (trastuzumab).
The Importance of Biomarker Testing
This study underscores the importance of biomarker testing for advanced or metastatic breast cancer. A single test can expand your treatment options, making it crucial to ask your doctor about testing for biomarkers, including PIK3CA mutations.
“This treatment is an excellent example of what’s called precision oncology. We need to match the right patient to the right treatment at the right time. To do that, we have to follow a specific criteria,” Dr. Juric said.
“Patients have to ask their physicians, do I qualify for this type of treatment? Have you analyzed my disease? Are you just relying on old school methods of analysis, estrogen receptor, progesterone receptor, HER2? Have you checked for mutations in this cancer? Drivers of this disease?”
Ask your doctor if the cancer was already tested for biomarkers, including PIK3CA mutations. If not, ask about testing options.
Approximately 40% of hormone receptor-positive metastatic breast cancers have this mutation and Inavolisib works by blocking the activity of the PI3K protein. If the tumor tests positive, Inavolisib could be a potential treatment.
Quality of Life and Possible Side Effects
According to the new study, Inavolisib was generally well-tolerated, with milder side effects than other drugs that target the PIK3CA mutation. Side effects were manageable in the first month of treatment and seemed to go away more quickly.
Common common side effects included:
- Diarrhea
- Mouth sores
- Skin rash
It’s important to report any side effects right away.
This study also looked at quality of life. Participants in the inavolisib group went longer (over a year) without cancer-related pain getting worse. They were also less bothered in general by the drug combination. Most answered “not at all” or “a little bit” when asked how bothered they were by the side effects of treatment in the past week.
“We ask patients, Hey, now you’re getting three drugs versus two drugs: does this bother you? Are toxicities difficult?” Dr. Juric explained to SurvivorNet.
“And when we ask that simple question, we see the majority of patients say that actually there is no dramatic increase in the toxicities and the overall symptom burden. So when you put all of that together with the efficacy of the drug, you now have a compelling set of data that suggests that this treatment should really be the one to choose in this particular type of disease”
Questions to Ask Your Doctor
- When will Inavolisib be FDA approved?
- How will I feel during treatment?
- What are the most common side effects of Inavolisib?
- What will my treatment cost?
- Will my treatment be covered by my medical insurance company?
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