mTOR Inhibitors in Cancer: — Everolimus and Temsirolimus

No. Everolimus and temsirolimus are targeted therapies, not chemotherapy. Chemotherapy works by damaging rapidly dividing cells throughout the body — which is why it often causes hair loss, severe nausea, and bone marrow suppression. mTOR inhibitors work differently: they block a specific molecular switch inside cancer cells. The side effect profile is different, though side effects still occur and need monitoring. The distinction matters because the two treatments work by different mechanisms, and being on one does not mean you have had chemotherapy.

Treatment continues for as long as the cancer is responding and the side effects are manageable. There is no fixed course length in the way chemotherapy is often given in cycles with a planned end date. Your oncologist will monitor response with scans at regular intervals and will review the benefit-to-burden balance at each assessment. If the cancer starts growing again or side effects become intolerable, the approach is reconsidered. Some people are on these drugs for months; others for longer periods. Your team will not continue a treatment that is no longer working.

Grapefruit and grapefruit juice should be avoided with everolimus. They affect the enzyme that processes the drug in your body, which can lead to higher drug levels and a greater risk of side effects. The same applies to Seville oranges. Herbal supplements — including commonly used preparations such as turmeric capsules, ashwagandha, or St. John's Wort — can also affect how the drug is metabolised. Tell your oncology team about everything you are taking, including Ayurvedic preparations and homeopathic remedies, before you start treatment and at every appointment after.

Eligibility is more often driven by cancer type, stage, and treatment history than by a single mutation test. That said, specific molecular changes — including mutations in PIK3CA, loss of the PTEN tumour suppressor, or mutations in TSC1 or TSC2 — activate the mTOR pathway and are part of the biology that makes certain cancers respond to these drugs. For tuberous sclerosis complex, the TSC1 or TSC2 mutation is central to eligibility. For other cancers, your oncologist will explain which criteria apply to your situation and what testing has been or will be done.

If imaging shows the cancer growing despite treatment, your oncologist will review the available options. In many cancer types there are further treatment lines — other targeted drugs, immunotherapy, chemotherapy, or clinical trials — and the decision depends on what you have already had, your current fitness, and what the evidence supports for your cancer at that stage. Stopping an mTOR inhibitor does not mean all options are exhausted. Ask your oncologist what the next step would be so you are not left uncertain about what follows.

Everolimus and temsirolimus are both used at CION centres. Everolimus, as a daily oral tablet, is managed through your outpatient appointments. Temsirolimus, given by infusion, is administered as day care so you do not need an overnight admission. Monitoring blood tests — including blood sugar, cholesterol, and blood counts — are arranged regularly as part of your treatment plan. If scans such as PET-CT are needed to assess your response, these are coordinated with partner imaging centres.