Previous attempts to establish P-gp inhibiting drugs as chemotherapy sensitizers in MM have failed due to undesirable pharmacokinetic interactions of the drugs used, their inability to achieve sufficiently high plasma concentrations and the lack of a diagnostic setup to safely identify patients with P-gp overexpressing MM.58 NFV and LPV are off-the-shelf drugs that overcome these limitations and may be tested in clinical trials. Here, PGP is linked to Miyoshi myopathy.