More recently, tetrandrine (CBT-1®; NSC-77037), a bis-benzylisoquinoline alkaloid isolated from Stephania tetrandra and found to modulate the P-gp inhibitory activity23, was submitted to phase I clinical trials (www.ClinicalTrials.gov; NCT03002805) to investigate its utility in the treatment of drug resistant cancers, in combination with doxorubicin. Here, PGP is linked to cancer.