CPSA 2011

Science and Technology Coming Together to Make a Difference

October 3 - 6, 2011
Bucks County Sheraton Hotel
Langhorne, PA

Program Abstract

Wednesday, 2:15 pm

Challenges & Solutions in the Quantitative Analysis of Large Therapeutic Peptides

Dr. Fabio Garofolo
Vice President, Bioanalytical Services
Algorithme Pharma Inc., Laval (Montreal), QC, Canada

During the last decade several therapeutic peptides became vital medicine for seriously ill patients and their quantification has become extremely important in the pharmaceutical industry. There are now about 60 approved therapeutic peptides, about 140 peptide candidates in clinical trials and it has been estimated that around 600 peptides are in pre-clinical development according to the Peptide Therapeutics Foundation. Peptides target different indications in oncology, metabolic, cardiovascular and infectious diseases and a wide variety of medical disorders from endocrinological lesions to pain and hematology. However, the development and validation of reliable quantitative methods by LC-MS/MS for large therapeutic peptides is extremely challenging due to their high molecular weight (around 2000 Daltons), non-specific binding, stickiness, low sensitivity, pronounced matrix effect and instability. Moreover, since these peptides are of natural origin or semi-synthetic the drug itself is constituted by some main components and many minor components (multi-components nature of complex core drugs) with different level of glycosylation that contributes to their heterogeneity. Finally, this class of compounds has characteristics that are between large and small molecules and conventional methods and criteria used for small molecules bioanalysis usually fail when employed to quantify these drugs. The choice of appropriate internal standards (ISs) is key in regulated bioanalysis for their successful and reliable quantitation. Stable labeled ISs are ideal for this task but they are typically not available hence, analogue ISs are used. However, the criteria for choosing the right analogue IS for large peptides are very different from the ones used for small molecules. The compounds studied in this work were semi-synthetic glycosylated peptides of natural origin structurally modified (dimethyl-propylamide-residue, diethyl-propylamide-residue, 2-methyl-phenylacetic-acid-residue or 3,5-methyl-phenylacetic-acid-residue). Innovative and specific bioanalytical strategies that were developed to overcome the analytical problems and general criteria to select an IS able to greatly improve the performance of large peptides quantification will be presented.

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