Inavolisib (Itovebi)

Inavolisib (Itovebi) is an FDA-approved targeted therapy that treats advanced or metastatic hormone receptor-positive, HER2-negative breast cancer that tests positive for a mutation on the PIK3CA gene.

Inavolisib is taken with another targeted therapy, palbociclib (Ibrance), and the hormonal therapy fulvestrant (Faslodex).

Inavolisib is the third medicine approved to treat PIK3CA-mutated breast cancers. Your doctors may discuss these other medicines if you have hormone receptor-positive breast cancer that has a PIK3CA mutation:

• Alpelisib (Piqray)
• Capivasertib (Truqap)

The FDA approved inavolisib based on results from a study called INAVO120. In this trial, adding inavolisib to treatment with palbociclib and fulvestrant reduced the risk of cancer growing by 57%.

How inavolisib works

Your cells use an enzyme called PI3K to control cancer growth and communicate with other cells. But in some breast cancers, a mutation on the PIK3CA gene can cause the PI3K enzyme to become overactive. This can allow breast cancer to grow.

Inavolisib is a PI3K inhibitor, which means it works by blocking the signals through the PI3K pathway. The combination of inavolisib, fulvestrant, and palbociclib can control cancer growth better than hormonal therapy and palbociclib alone.

Who gets inavolisib?

Inavolisib is a targeted therapy for people with hormone receptor-positive, HER2-negative breast cancer that is locally advanced or metastatic.

People diagnosed with breast cancer may be treated with inavolisib if they meet these requirements:

• They were treated for early-stage breast cancer, and the cancer returned during or shortly after treatment with hormonal therapy.
• They received no previous treatments for metastatic breast cancer.
• The cancer tests positive for a mutation in the PIK3CA gene.

Tests to confirm if inavolisib is an option for you

Biomarker tests for hormone receptor, HER2, and PIK3CA mutation status can help confirm whether inavolisib may be an option for you.

Tests for hormone receptor status and HER2 status

Your healthcare team can confirm the cancer’s hormone receptor status and HER2 status using a sample taken with a biopsy followed by an immunohistochemistry (IHC) test.

If you were initially diagnosed with early-stage breast cancer and have now experienced a recurrence:

• The cancer should be rebiopsied and retested for hormone receptor and HER2 status.
• This is because the status can sometimes be different at the time of recurrence.

Tests for PIK3CA mutation status

A next-generation sequencing (NGS) test looks for changes in the cancer’s DNA, including mutations in the PIK3CA gene.

The test for a PIK3CA mutation uses a blood sample. Your doctor will order a blood draw and submit a sample to a lab. There it will be examined using an NGS blood test such as FoundationOne Liquid CDx.

The test will look at pieces of cancer cell DNA that are found in the blood. A report from the lab will say if the cancer has a PIK3CA mutation.

How inavolisib is given

Inavolisib is part of a combination therapy that includes palbociclib and fulvestrant. Treatment includes daily pills at home and a monthly injection by a healthcare provider.

• Inavolisib is a nine mg pill taken at home. The recommended dose is one pill taken daily, with or without food. You should try to take inavolisib at around the same time each day. There are no food restrictions for inavolisib, but be sure to review the warnings for all medicines you take.
• Palbociclib is a 125 mg pill taken at home. Palbociclib is given in a four-week cycle. You will take one 125 mg capsule or tablet every day for 21 days followed by a seven-day break. You will continue to take daily inavolisib even on days you are not taking palbociclib.
• Fulvestrant is a 500 mg injection. A healthcare provider will give your fulvestrant injections at your treatment center or a doctor’s office. Fulvestrant is given twice during the first month of treatment, on day one and day 15. After that, you will get fulvestrant once every 28 days.

Healthcare providers may prescribe a gonadotropin-releasing hormone (GnRH) agonist to go with inavolisib treatment. A GnRH works by temporarily lowering the level of certain hormones in the body. In women, they slow the functions of the ovaries.

• If you are a woman who has not reached menopause or you have recently started menopause, your doctor will recommend a GnRH.
• If you are a man, your doctor may recommend a GnRH. The approval for inavolisib leaves this decision up to your doctor. Ask why they do or do not recommend a GnRH for you.

Side effects and things to remember

Inavolisib comes with warnings for side effects that can be severe, such as:

• Increased blood sugar
• Mouth sores
• Diarrhea

Your doctor will order regular tests to check for some of these effects. But you should also report any side effects you experience.

Before treatment begins, tell your doctor if you have a history of any conditions that could affect your risk for these side effects, including:

• Diabetes or high blood sugar
• Kidney problems

Inavolisib is not safe for an unborn baby. Let your doctor know if:

• You are pregnant or planning to become pregnant
• You are breastfeeding

Women who can get pregnant and men with partners who can get pregnant should use birth control during treatment. Continue birth control the whole time you are taking inavolisib and for one week after the final dose. Women taking inavolisib should use a nonhormonal option.

Inavolisib can affect fertility in women and men. If the ability to have children in the future is a concern for you, ask your doctor about options for protecting your fertility before starting treatment.

Other common side effects include:

• Low white blood cell counts (neutropenia)
• Low red blood cell counts
• Higher levels of creatinine, a waste product left after the body digests protein
• Low levels of calcium, potassium, sodium, or magnesium
• Fatigue
• Higher liver enzymes, which means damage or inflammation of the liver
• Nausea
• Rash
• Loss of appetite
• COVID-19 infection
• Headache

Tell your doctors about any other medicines you are taking. Include other prescription medicines as well as over-the-counter medicines, vitamins, and herbal supplements.

Paying for inavolisib

Your health insurance coverage may pay for part or all of the cost of inavolisib. Discuss any concerns with your healthcare team and your insurance provider before starting treatment.

If you are concerned about your ability to pay for treatment, you may be able to find assistance from the manufacturer, Genentech. People who have insurance may apply for help through the Genentech Co-pay Assistance Program to cover co-pays or co-insurance. These are the costs that you may be responsible for after insurance pays the rest.

For people without insurance or who have financial situations that meet certain guidelines, the Genentech Patient Foundation may provide inavolisib for free.

You may face other costs related to your care while taking inavolisib. Transportation, time off work, and childcare are just some of the ways that expenses can increase during breast cancer treatment. Visit our Financial matters page to find information and resources that can assist you during care.