Evaluation of Different Numbers of Dilution Serials of Biological Samples Tested in Cell-Based Functional Assays

• Activity Number: 423
• Type: Contributed
• Date/Time: Tuesday, August 2, 2011 : 2:00 PM to 3:50 PM
• Sponsor: Biopharmaceutical Section
• Author(s): Liping Song*+ and Robert Capen
• Companies: Merck & Co., Inc. and Merck & Co., Inc.
• Keywords: parallelism ; relative potency ; duplicate dilution serial

Abstract

In cell-based functional assays, it is a common practice for the laboratory to test a biological sample along with a corresponding reference standard both in multiple dilution serials on 96-well micro-titer plates in at least three independent plates. The relative potency of the test sample is determined after confirming parallelism of corresponding dilution response curves from each plate, and the geometric mean relative potency from three independent plates is used to estimate the true relative potency of the sample. How many dilution serials of a sample and reference standard are sufficient on each plate: singlet, duplicate, triplicate, or even quadruplicate? Too few replicates might introduce an error in measurement, leading to an unreliable estimate. Too more replicates would be time consuming and waste resources. This presentation compares the determined relative potencies and associated variability with different numbers of dilution serials of a sample through bootstrap simulation. The results show that duplicate dilution serials of a sample are sufficient in most cases although multiple dilution serials provide some benefits during early development of the assays.