Screening Falsified Biologic Drug Products with A-TEEM Spectroscopy

Absorbance - Transmission, Excitation Emission Matrix (A-TEEM) spectroscopy was evaluated for a novel application of screening falsified biologic drug products. Some falsified biologics are challenging to screen with fast, inexpensive analytical tools. For example, authentic BMS biologics which are falsified by market diversion (i.e. smuggling) require high specificity analytical methods to ensure patient safety. However, traditional peptide mapping techniques are too slow, expensive, and labor intensive for screening suspect products in a high-throughput forensics laboratory. A proof-of-principle study was performed in collaboration with the analytical instrument vendor, HORIBA, to evaluate the specificity of A-TEEM for similar immunoglobulin G (IgG) protein structures. A-TEEM is a three-dimensional spectroscopic technique, which can characterize the composition and local environment of the aromatic amino acid residues tyrosine and tryptophan. Two groups of commercial drug substance IgG proteins were selected based on primary structure similarity: 1. Six (6) proteins with the same number of tyrosine and tryptophan residues per molecule and 2. Five (5) proteins with sequence similarity (93-95% homologous). The A-TEEM spectra were measured in the same buffer on a HORIBA Aqualog spectrometer. The A-TEEM profiles were analyzed using a multivariate statistical technique named Parallel Factor Analysis (PARAFAC) to extract the reproducible features of the fluorescence profiles. Although the A-TEEM plots appear visually broad and featureless, the PARAFAC model was able to distinguish these IgG samples. This talk will present results of the application of A-TEEM spectroscopy and chemometrics to the discrimination of similar biologic drug substances for the purpose of suspect biologic drug screening.