[SDZ PSC 833: a novel modulator of MDR]

Area of Science:

• Pharmacology
• Oncology
• Drug Discovery

Background:

• Multidrug resistance (MDR) in cancer cells, mediated by P-glycoprotein (P-gp), significantly limits chemotherapy efficacy.
• SDZ PSC 833 is a novel compound designed to overcome P-gp-mediated MDR.

Purpose of the Study:

• To evaluate the efficacy of SDZ PSC 833 in reversing MDR in cancer cells.
• To assess the in vitro and in vivo activity of SDZ PSC 833 in combination with anticancer drugs.
• To determine safe and effective dosing regimens for SDZ PSC 833 in clinical trials.

Main Methods:

• In vitro studies assessing SDZ PSC 833 interaction with P-gp and its effect on intracellular drug concentrations.
• In vivo studies evaluating the potentiation of anticancer drug activity in sensitive and MDR tumor models.
• Phase I/II clinical trials to establish recommended doses, assess toxicity, and evaluate pharmacokinetic interactions.

Main Results:

• SDZ PSC 833 restored intracellular anticancer drug levels in MDR cells at concentrations of 0.8-3.0 microM.
• In vivo, SDZ PSC 833 significantly enhanced the anti-tumor activity of various anticancer drugs in both sensitive and MDR tumors.
• Recommended doses were established, with dose-limiting toxicity being reversible ataxia. Pharmacokinetic adjustments for concomitant anticancer drugs were necessary.

Conclusions:

• SDZ PSC 833 effectively reverses P-gp-mediated MDR in vitro and potentiates anticancer drug efficacy in vivo.
• Clinical studies demonstrated tumor responses in advanced-stage cancer patients, supporting its use.
• SDZ PSC 833 may suppress MDR1 gene activation, suggesting potential application in earlier disease stages.