How might ketoconazole and rifampicin affect exposure to SN-38 during treatment with sacituzumab govitecan?

During sacituzumab govitecan treatment, ketoconazole (a UGT1A1 inhibitor) may increase SN-38 exposure and rifampicin (a UGT1A1 inducer) may substantially reduce it, although limited patient data showed comparable free SN-38 exposure with and without these drug classes; use cautiously with close monitoring.