CYP3A4 and cancer: Based on these results, it is recommended that concomitant use of strong CYP3A4 inhibitors should be avoided (e.g., ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, and voriconazole) in cancer patients receiving 25 mg i.v. temsirolimus once weekly.