A U.S. Patent for a “Process for Reducing Subvisible Particles in a Pharmaceutical Formulation” was awarded to Regeneron on July 9th, 2019. The present invention provides a stable protein composition containing a surfactant and having less than 400 subvisible particles of 10 microns or greater diameter per container, or less than 10,000 subvisible particles of 2 microns or greater per container. A method of manufacturing such a stable protein composition is disclosed, which includes a unit of operation that removes or decreases an esterase activity that degrades the surfactant. The unit of operation may be hydrophobic interaction chromatography or filtration, mixed mode chromatography, or the like. Learn More