Everolimus is a prescription medication used to treat several types of cancer, prevent organ transplant rejection, and manage complications of a genetic condition called tuberous sclerosis complex (TSC). It works by blocking a protein called mTOR, which tells cells when to grow, divide, and survive. When this protein malfunctions, it can drive tumor growth or cause an overactive immune response. By suppressing mTOR, everolimus slows cell growth across a range of conditions.
Cancer Treatment
Everolimus is approved under the brand name Afinitor for several cancers where the mTOR signaling pathway plays a role in tumor growth. Its most established cancer use is in advanced, hormone receptor-positive, HER2-negative breast cancer. For postmenopausal women whose cancer has progressed after initial hormone therapy, everolimus is paired with an aromatase inhibitor called exemestane. The landmark BOLERO-2 trial showed this combination significantly extended the time before the cancer worsened compared to exemestane alone. The typical starting dose is 10 mg daily, with reductions to 5 mg if side effects become difficult to manage.
Everolimus is also used for advanced kidney cancer. Current guidelines list it as an option for non-clear cell renal cell carcinoma, a less common subtype that doesn’t respond well to standard treatments. It’s sometimes combined with other targeted therapies in this setting. Beyond breast and kidney cancer, everolimus is approved for progressive pancreatic neuroendocrine tumors, a type of cancer where mTOR signaling directly fuels cell division and survival.
Tuberous Sclerosis Complex
TSC is a genetic disorder that causes noncancerous tumors to grow in the brain, kidneys, and other organs. Everolimus is approved (under the brand name Votubia in some countries, Afinitor Disperz in the U.S.) for three distinct TSC-related problems.
The first is subependymal giant cell astrocytoma (SEGA), a type of brain tumor that develops in people with TSC. Everolimus can shrink these tumors and is used when surgery isn’t a good option. The second is renal angiomyolipoma, a kidney tumor that carries a risk of bleeding as it grows. In the EXIST-2 clinical trial, 42% of patients treated with everolimus saw their kidney tumor volume shrink by at least half, compared to 0% on placebo. That response improved over time: by 96 weeks, nearly 65% of patients had achieved the same level of shrinkage, and by 144 weeks, the figure reached 72%. The median time to see a response was about three months.
The third and most recently approved TSC indication is partial-onset seizures. In 2018, the FDA approved everolimus tablets for oral suspension as an add-on treatment for adults and children aged 2 and older with TSC-associated seizures that haven’t been fully controlled by other medications.
Organ Transplant Rejection Prevention
Under the brand name Zortress, everolimus is used to prevent rejection in kidney and liver transplant recipients. It serves a different strategic purpose here than traditional anti-rejection drugs. The older class of immunosuppressants called calcineurin inhibitors (like tacrolimus) are highly effective at preventing rejection but can cause significant kidney damage over time. Chronic kidney failure is one of the most common long-term complications after liver transplantation, largely driven by these drugs.
Everolimus offers a way around this problem. When combined with a reduced dose of tacrolimus, it provides equivalent protection against rejection while preserving kidney function. A major study published in the American Journal of Transplantation found no significant difference in rejection rates, graft loss, or death between patients on everolimus plus reduced tacrolimus versus standard tacrolimus alone. The benefit was better kidney health without the wound healing problems seen with sirolimus, an older drug in the same class. Everolimus is cleared from the body faster than sirolimus (a half-life of about 28 hours versus 60 hours), is more easily absorbed, and appears to have a cleaner side effect profile in transplant patients.
How Doctors Monitor Treatment
Everolimus requires regular blood tests to make sure the drug stays within a therapeutic range. For most indications, doctors aim for trough concentrations (the lowest level in your blood, measured just before the next dose) between 5 and 10 nanograms per milliliter. The first check typically happens about two weeks after starting treatment, and doses are adjusted up or down based on results. Levels between 10 and 15 ng/mL may be acceptable if you’re tolerating the drug well and your condition is responding, but levels above 15 ng/mL require a dose reduction.
This monitoring matters because everolimus has a narrow window between effective and problematic. Too little won’t control the disease. Too much raises the risk of side effects without additional benefit.
Common Side Effects
Everolimus causes noticeable side effects in most people who take it, particularly at the 10 mg cancer dose. The most frequent issue is stomatitis, or mouth sores, which affected 44% of patients in clinical trials compared to 8% on placebo. Infections occurred in 37% of patients, reflecting the drug’s immune-suppressing activity. About 30% of patients experienced fatigue, cough, or diarrhea.
Rash affects roughly 29% of patients, and nausea about 26%. Swelling in the hands and feet, loss of appetite, and shortness of breath each occur in about one in four people. A more concerning side effect is pneumonitis, an inflammation of the lungs, which appeared in 14% of patients on everolimus versus none on placebo. Other effects include nosebleeds (18%), headache (19%), dry skin (13%), and changes in taste (10%).
Many of these side effects are manageable with dose reductions or supportive care. The mouth sores in particular tend to be the side effect that most disrupts daily life, but they can often be controlled with special mouthwashes and, if needed, a temporary dose decrease.
Afinitor vs. Zortress
Though both contain everolimus, Afinitor and Zortress are not interchangeable. Afinitor is the cancer and TSC formulation, available in standard tablets and dissolvable tablets (Afinitor Disperz) for patients who have difficulty swallowing. Zortress is specifically formulated for transplant patients at different doses. The two brands target different conditions, use different dosing strategies, and should never be substituted for each other. Your prescribing team will use the correct formulation based on your specific diagnosis.