Microfluidic Modulation Spectroscopy of a Biotherapeutic at Low to High Concentrations without Interference from Formulation Excipients

Libo Wang and Jeffrey Zonderman, RedShiftBio, and Ioannis A. Papayannopoulos and Shannon Renn-Bingham, Celldex

Microfluidic Modulation Spectroscopy (MMS), a novel protein characterization technique was used to measure the secondary structure of a monoclonal antibody on a RedShiftBio AQS3pro instrument at concentrations from 1 to80 mg/mL in both the formulation buffer (10 mM Histidine,245 mM Trehalose, 10 mM Methionine, 0.05% PS-20, pH5.2) and a pH 7.4 PBS buffer. Our results show that the absolute absorbance and the second derivative spectra of the mAb samples at 1-80 mg/mL in both buffers are closely matched suggesting very similar secondary structure profiles of these samples. There is no secondary structure changes of the mAb when diluted in the PBS buffer. When compared to the 5 mg/mL sample in the formulation buffer, the structure similarity is 98.5% for 1 mg/mL sample in the formulation buffer, and 99+% for all other samples in both buffers indicating all these samples are highly comparable. The mAb sample also displays great quantitation linearity of measurements at 1 to 80 mg/mL in both buffers with a R2value of 0.999, respectively. In addition, the secondary structure composition of these samples in both buffers is very consistent, i.e. 60-62% beta sheet structure, 29-31%turn structure and very small amount of alpha-helix structure. No dilution of high concentration samples is required for MMS measurements and there are no interferences from optically active excipients in the formulation buffer. Our results show that MMS is a powerful protein characterization technique providing comparability, similarity, quantitation linearity and HOS information of protein samples with high sensitivity and accuracy.