xPLOREing possibilities on the SMCxPRO™ platform: Development of an ultra-sensitive PK assay using custom assay services.

First in human (FIH) clinical trials of bispecific immunostimulatory antibodies commonly require a low starting dose based on a minimum anticipated biological effect level (MABEL) approach.  To quantify serum drug concentrations at low dose levels, an ultrasensitive pharmacokinetic (PK) assay is required for Aptevo’s bispecific antibody, ADAPTIR-X. The SMCxPRO™ platform was identified as potentially having the capability to reach the required assay sensitivity.   A feasibility assessment was undertaken utilizing MilliporeSigma’s Custom Assay & Sample Testing (CAST) team and the custom assay development SMCxPLORE™ option, including testing of sensitivity, matrix effects, accuracy, and precision.  From initial discussions to sample analysis, Aptevo and the SMC™ team efficiently collaborated to produce high quality, informative data, leading to the purchase and implementation of SMCxPRO™ technology at Aptevo.  This presentation will introduce the CAST team and their in-house custom assay services, as well as describe the steps taken during the SMCxPLORE™ feasibility assessment to achieve a sensitivity of ~0.32 pg/mL for the ADAPTIR-X PK assay.