mTOR inhibitor Pregnancy: Based on findings in animal studies and its mechanism of action, temsirolimus can cause fetal harm when administered to a pregnant woman. There are no data in pregnant women; adverse embryo-fetal effects occurred in rats and rabbits at sub-therapeutic human exposures. Advise pregnant women of the potential hazard to a fetus (§8.1).

Temsirolimus (Specialist drug)

Brand names: Torisel

Temsirolimus is an intravenous mTOR inhibitor used in the treatment of advanced renal cell carcinoma and mantle cell lymphoma. It is a specialist drug given under oncology supervision.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Advanced renal cell carcinoma: 25 mg once a week.

Route: Intravenous infusion over a 30-60 minute period. The vial contents must first be mixed with the enclosed 1.8 mL diluent (giving 10 mg/mL), then the required volume further diluted into 250 mL of 0.9% sodium chloride injection; administer through polyethylene-lined administration sets and store the final dilution in glass/polypropylene bottles or polypropylene/polyolefin bags to minimise DEHP exposure.

Frequency: Once weekly, continued until disease progression or unacceptable toxicity occurs.

Premedication: prophylactic intravenous diphenhydramine 25 to 50 mg (or similar antihistamine) approximately 30 minutes before the start of each dose (§2.2). Mild hepatic impairment (bilirubin more than 1 to 1.5 x ULN, or AST above ULN with bilirubin at or below ULN): reduce the dose to 15 mg/week (§2.4). Concomitant strong CYP3A4 inhibitors should be avoided; if unavoidable, consider reducing the dose to 12.5 mg/week, and allow a washout of approximately 1 week after stopping the inhibitor before returning to the previous dose. Concomitant strong CYP3A4 inducers should be avoided; if unavoidable, consider increasing the dose from 25 mg/week up to 50 mg/week, returning to the previous dose when the inducer is stopped (there are no clinical data with either adjustment). Grapefruit juice may increase sirolimus concentrations and should be avoided. Administration of the final diluted solution should be completed within six hours from the time the vial is first diluted. Paediatric: effectiveness in paediatric patients with advanced recurrent/refractory solid tumours has not been established; in a phase 1-2 study, doses of 10 mg/m2 to 150 mg/m2 as a 60-minute weekly infusion (phase 1) and 75 mg/m2 weekly (phase 2) were studied, with no objective responses except 1 of 19 neuroblastoma patients (§8.4) — this is not an approved paediatric regimen. Source notes: no UK SPC (eMC) record was fetched, so the regimen is from the US prescribing information; and the fetched §2.3 'Dosage Interruption/Adjustment' text is garbled/incomplete (the ANC and platelet cut-offs for holding therapy are missing) — the clinician must verify the interruption thresholds against the full label.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Bilirubin greater than 1.5 x ULN (US label §4)

Side effects

Rash
Asthenia
Mucositis
Nausea
Oedema
Anorexia

Interactions

Strong CYP3A4 inhibitors — avoid (e.g. ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole); ketoconazole increased sirolimus AUC 3.1-fold and Cmax 2.2-fold. If unavoidable, consider 12.5 mg/week
Strong CYP3A4/5 inducers — avoid (e.g. dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, phenobarbital); rifampin decreased sirolimus Cmax by 65% and AUC by 56%. If unavoidable, consider increasing to 50 mg/week
Grapefruit juice may increase plasma concentrations of sirolimus (a major metabolite) and should be avoided
Angioedema has been reported with mTOR inhibitors combined with ACE inhibitors and calcium channel blockers

Clinical monograph

How it works

It inhibits the mTOR kinase, blocking signalling pathways that drive cell-cycle progression, angiogenesis and tumour growth.

Prescribing in practice

Hypersensitivity and infusion reactions can occur, so antihistamine premedication is given and infusions are administered with close monitoring.
It commonly causes metabolic disturbances including hyperglycaemia, hyperlipidaemia and an increased infection risk, alongside non-infectious pneumonitis.
It is metabolised via CYP3A4, so strong inhibitors and inducers and concurrent live vaccines should be avoided.

Monitoring

Monitor blood glucose, lipids, full blood count, renal and liver function, and watch for respiratory symptoms suggestive of pneumonitis.

Counselling the patient

Report new or worsening breathlessness, cough or fever, which need prompt assessment.
Attend for blood tests to check your blood sugar, cholesterol and blood counts.
Tell your team about all other medicines, as some interact with this treatment.

Evidence & guidelines

Temsirolimus improved overall survival versus interferon in poor-prognosis advanced renal cell carcinoma in a pivotal randomised trial.

Reference: NICE TA178; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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