The USPTO issued patent US12595336B2, a granted patent covering a method for producing maleimide polyethylene glycol derivatives using silica-gel-assisted deprotection to achieve high maleimidization rates while preventing deterioration of the maleimide group. The patent claims priority to application 18256951 filed December 8, 2021.

For pharmaceutical manufacturers and biopharmaceutical companies developing PEGylated therapeutics or antibody-drug conjugates, this patent establishes NOF Corporation's proprietary process for maleimide PEG production. Competitors developing similar PEG linker technologies may need to design around this patent or seek licensing arrangements. Research institutions and CDMOs working with maleimide PEG reagents should evaluate freedom-to-operate implications for their manufacturing processes.