PGP and renal cell carcinoma: Sato et al. have shown that combining P-gp inhibitor elacridar with sunitinib enhances the cytotoxic effect in a renal cell carcinoma model [53]; and it would be interesting to investigate the effect of such a P-gp inhibitor on drug accumulation and sensitivity in our HDST setting, including in TKI-resistant PDTO CRC models.