MDQ diagnostic kit

Functionally detects multidrug resistance in tumor cells

Multi-drug resistance (MDR) is a major factor in the failure of many forms of chemotherapy. In the past few years it has become widely accepted that this resistance correlates with the overexpression of at least two ATP dependent drug-efflux "pumps". These cell membrane proteins, called P-glycoprotein (P-gp, MDR1) and multidrug-resistance-associated protein (MRP1), are members of the ABC transporter family. The following figure demonstrates the process in which an MDR transporter causes multidrug resistance.

SOLVO's patented Calcein assay in the MultiDrugQuant^™ assay kit was developed for the functional and quantitative determination of multidrug resistance caused by both MDR1/P-gp (ABCB1) and MRP1 (ABCC1) activities in tumor cells of hematological malignancies. The kit allows the user to monitor drug sensitivity of the malignancy, design proper therapeutic interventions and personalize the chemotherapy.

The MultiDrugQuant^™ assay kit is based on determining fluorescence intensities after a short in vitro incubation of the cell suspension with the calcein-acetoxymethylester (calcein AM), with or without the addition of selective inhibitors of MDR1 and MRP1.

Calcein AM, a non-fluorescent hydrophobic dye molecule rapidly penetrates cell membranes and becomes trapped intracellularly upon conversion into fluorescent calcein by non-specific esterases. Following a short incubation, the intracellular free dye concentration can increase up to 100-500-times that of the calcein AM in the medium. In the MDR1 and/or MRP1-expressing cells calcein AM is extruded by the multidrug transporter before its intracellular conversion to free-calcein. However, when this calcein AM extrusion is blocked by an agent that interferes with the MDR1 and/or MRP1 pump-activity, the fluorescent free calcein rapidly accumulates intracellularly. By using a simple mathematical formula, a Multidrug Resistance Activity Factor (MAF) can be calculated from cellular fluorescence data. Since the assay includes an internal standard, the obtained MAF values provide valuable opportunity for the intra-laboratory and inter-laboratory comparison of multidrug resistance of tumor cells.

The MultiDrugQuant^™kit includes reagents for at least 20 independent MDR/MRP measurements, carried out in triplicates, and a CD with a booklet concerning the scientific background and describing the assay protocol.

MDQ is designed as a routine laboratory flow cytometry method, offering several advantages over currently used methods:

The first clinical trial using Solvo's patented technology demonstrated that the MDQ kit "[...] present a standardized form of the calcein assay: that is, a reproducible, inexpensive, feasible and quantitative functional test for MDR detection can be easily used in routine clinical laboratories. These investigations verified the correlation between the clinical outcome and the test results and estimated a high predictive value of the assay for therapy response. Therefore, it should be considered a clinically relevant method for examining MDR activity."(Kar�szi �., et al., British Journal of Haematology 2001, 112 (2), pp. 308-314)

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