What Is Inavolisib (Itovebi)? FDA Approval, Authorization and Reimbursement Status in Turkey
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Next-Generation PI3K Blockade in Breast Cancer Treatment: Itovebi
A breakthrough in the treatment of locally advanced or metastatic breast cancer, Itovebi (inavolisib)is a highly selective targeted antineoplastic agent that specifically blocks cell growth signals in patients with a PIK3CA mutation.
Drug Profile
- Brand Name: Itovebi
- Active Ingredient: Inavolisib
- Class: PI3K (phosphatidylinositol 3-kinase) Alpha Inhibitor
- Route of Administration: Oral (Tablet)
- Manufacturer: Genentech, Inc. (Roche Group)
- Authorization: Not yet authorized in Turkey.
- Reimbursement: Not included on the SGK reimbursement list.
- Access: May be obtained through Roche under an early access program.
- Estimated Price in May 2026: Based on overseas selling prices and exchange rates, the estimated monthly cost of treatment is approximately 18500 - 20000 USD (the current price for Turkey should be checked through the Turkish Pharmacists' Association - TEB).
Approved Indications
Itovebi is indicated as part of combination therapy (with palbociclib and fulvestrant) for patients with the following characteristics:
- PIK3CA Mutation Positive: A mutation confirmed by genetic testing.
- HR+/HER2-: Hormone receptor positive and HER2 receptor negative.
- Stage: Locally advanced or metastatic breast cancer.
FDA Approval History
The FDA approved Itovebi based on the results of the phase III INAVO120 trial. This trial showed that the combination reduced the risk of disease progression by 57%. The FDA had previously granted it Breakthrough Therapy designation.
What Is Inavolisib and How Does It Work at the Molecular Level?
Inavolisib is an inhibitor that targets the PI3K/AKT/mTOR pathway, the command center for cancer cell growth and survival.
🔬 How It Works at the Molecular Level
- 1. Selective PI3K-Alpha Inhibition:
It interrupts signaling by blocking the PI3K-alpha isoform, which becomes overactive because of a PIK3CA mutation. - 2. Signal Interruption and Energy Restriction:
It reduces tumor cell energy production, suppresses growth and triggers apoptosis (programmed cell death). - 3. Targeted Approach:
It does not directly damage DNA; it focuses on shutting down vital signaling pathways only in cells carrying the genetic mutation.
Administration and Dosage
Itovebi is generally available as 3 mg and 9 mg tablets and is part of a triple combination:
- Itovebi: 9 mg 1 time a day (with or without food).
- Palbociclib: 125 mg daily for 21 days, followed by a 7-day break (a 28-day cycle).
- Fulvestrant: 500 mg intramuscular injection (on days 1 and 15 of cycle 1; every 28 days in subsequent cycles).
Resistance Mechanisms
During treatment, cancer cells may develop the following ways to survive:
- Alternative Pathways: Activation of the RAS/RAF/MEK/ERK pathway.
- PTEN Loss: Disruption of the PTEN signaling suppression mechanism.
- Secondary Mutations: New genetic changes that prevent the drug from binding.
- Efflux Pumps: Expulsion of the drug from the cell through increased ABC transporter activity.
Side Effects and Statistical Rates
- Neutropenia (Low White Blood Cell Count): 89%
- Hyperglycemia (High Blood Sugar): 59% (Caution in patients with diabetes!)
- Mucositis / Stomatitis (Mouth Sores): 51%
- Diarrhea: 48% (Electrolytes must be monitored)
- Thrombocytopenia: 48%
- Anemia: 37%
- Other: Nausea (28%), rash (25%), fatigue (24%), visual changes (22%).
Special Situations and Warnings
- Drug Interactions (CYP3A4): Strong inhibitors such as ketoconazole and clarithromycin increase the drug's toxicity, while rifampicin and St. John's wort may reduce its effect.
- Pregnancy and Breastfeeding: There is a high risk of embryo-fetal toxicity. Effective contraception is essential during and after treatment.
- QT Prolongation: ECG monitoring is recommended when used with drugs such as ciprofloxacin or amiodarone.
- Liver and Kidney Monitoring: ALT, AST and creatinine levels should be monitored periodically.
Pharmacokinetic Summary
- Absorption: Intestinal absorption is high; fatty meals may increase absorption.
- Distribution: 95%+ plasma protein binding. Passage across the blood-brain barrier is limited.
- Half-Life: 20–30 hours (supports once-daily administration).
- Elimination: Primarily eliminated through bile and feces; urinary excretion is minimal.
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