The Netherlands-based Synaffix BV has expanded a deal focusing on its antibody-drug conjugate (ADC) linker tech with U.S. cancer biotech Mersana Therapeutics Inc., with the revised contract potentially paying out more than $1 billion. Privately owned Synaffix is hoping to ride a wave of interest in ADC technology, which is finally coming of age more than two decades after the first drug of this type was approved.