rifampin and temsirolimus

Temsirolimus is a novel inhibitor of the mammalian target of rapamycin, with antitumor activity in advanced tumors. Because temsirolimus and its metabolite, sirolimus, are cytochrome P450 (CYP) 3A4/5 substrates, the potential exists for interaction with drugs that induce CYP3A activity, including enzyme inducers and rifampin. Cancer patients received once-weekly intravenous (IV) 220 mg/m(2) temsirolimus with or without enzyme inducers. Coadministration with enzyme inducers decreased temsirolimus maximum plasma concentration (C(max)) by 36% and increased volume of distribution by 99%. Sirolimus C(max) and area under the concentration-time curve (AUC) were decreased by 67% and 43%, respectively. In healthy adult subjects, coadministration of 25-mg intravenous temsirolimus with rifampin had no significant effect on temsirolimus C(max) and AUC but decreased sirolimus C(max) and AUC by 65% and 56%, respectively. Rifampin decreased AUC(sum) by 41%. Temsirolimus was well tolerated in both studies. If concomitant agents with CYP3A induction potential are used, higher temsirolimus doses may be needed to achieve adequate tumor tissue drug levels.

Topics: Adolescent; Adult; Aged; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Enzyme Induction; Female; Glioma; Humans; Male; Middle Aged; Protein Kinase Inhibitors; Protein Kinases; Rifampin; Sirolimus; TOR Serine-Threonine Kinases

Reactivation of tuberculosis is rare in patients receiving chemotherapy for solid tumours, and poorly documented in patients receiving molecular targeted therapy. We report on a patient with metastatic renal-cell carcinoma treated with temsirolimus, who developed respiratory symptoms and mild fever after 6 weeks of treatment. CT-scan and laboratory tests were consistent with reactivation of tuberculosis. The patient received anti-tuberculosis therapy including rifampicin, a potent CYP3A4/5 inducer. After introduction of rifampicin-based treatment, the patient experienced tumour progression, leaving questionable the potential pharmacokinetic interaction between rifampicin and temsirolimus, a substrate for CYP3A4.

Topics: Aged, 80 and over; Antibiotics, Antitubercular; Antineoplastic Agents; Carcinoma, Renal Cell; Cytochrome P-450 CYP3A; Drug Interactions; Enzyme Induction; Humans; Kidney Neoplasms; Male; Neoplasm Metastasis; Rifampin; Sirolimus; Tuberculosis