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Open Access Research article

Synthesis of hapten and preparation of specific polyclonal antibody with high affinity for lenalidomide, the potent drug for treatment of multiple myeloma

Ibrahim A Darwish*, Nourh Z Alzoman, Reem M Abuhejail and Tilal E El-Samani

Author Affiliations

Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh, 11451, Saudi Arabia

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Chemistry Central Journal 2012, 6:125  doi:10.1186/1752-153X-6-125

Published: 26 October 2012

Abstract

Background

For therapeutic monitoring and pharmacokinetic studies of lenalidomide (LND), the potent drug for treatment of multiple myeloma (MM), a specific antibody was required for the development of a sensitive immunoassay system for the accurate determination of LND in plasma.

Results

In this study, a hapten of LND (N-glutaryl-LND) was synthesized by introducing the glutaryl moiety, as a spacer, into the primary aromatic amine site of the LND molecular structure. The structure of the hapten (G-LND) was confirmed by mass, 1H-NMR, and 13C spectrometric techniques. G-LND was coupled to each of bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH) proteins by ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling reagent. LND-KLH conjugate was used as an immunogen. Four female 2-3 months old New Zealand white rabbits were immunized with an emulsion of LND-KLH with Freund`s adjuvant. The immune response of the rabbits was monitored by direct enzyme-linked immunosorbent assay (ELISA) using LND-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and affinity to LND was scarified and its sera were collected. The IgG fraction was isolated and purified by affinity chromatography on protein A column. The specificity of the purified antibody for LND was evaluated by indirect competitive ELISA using dexamethasone as a competitor as it is used with LND in a combination therapy.

Conclusions

The high affinity of the antibody (IC50 = 10 ng/mL) will be useful in the development of an immunoassay system for the determination of plasma LND concentrations. Current research is going to optimize the assay conditions and validate the procedures for the routine application in clinical laboratories.

Keywords:
Multiple myeloma; Lenalidomide; Polyclonal antibody; ELISA; Therapeutic monitoring; Pharmacokinetic studies