P-Glycoprotein (ABCB1/MDR1) and BCRP (ABCG2) Limit Brain Accumulation and Cytochrome P450-3A (CYP3A) Restricts Oral Exposure of the RET Inhibitor Selpercatinib (RETEVMO).

Selpercatinib is a targeted, FDA-approved, oral, small-molecule inhibitor for the treatment of rearranged during transfection (RET) proto-oncogene mutation-positive cancer. Using genetically modified mouse models, we investigated the roles of the multidrug efflux transporters ABCB1 and ABCG2, the OATP1A/1B uptake transporters, and the drug-metabolizing CYP3A complex in selpercatinib pharmacokinetics. Selpercatinib was efficiently transported by hABCB1 and mAbcg2, but not hABCG2, and was not a substrate of human OATP1A2, -1B1 or -1B3 in vitro.

ABCB1 and ABCG2, but not CYP3A4 limit oral availability and brain accumulation of the RET inhibitor pralsetinib.

Background And Purpose: Pralsetinib is an FDA-approved oral small-molecule inhibitor for treatment of rearranged during transfection (RET) proto-oncogene fusion-positive non-small cell lung cancer. We investigated how the efflux transporters ABCB1 and ABCG2, the SLCO1A/1B uptake transporters and the drug-metabolizing enzyme CYP3A influence pralsetinib pharmacokinetics.

Experimental Approach: In vitro, transepithelial pralsetinib transport was assessed.