Mersana Therapeutics has formed a collaboration with Endo Pharmaceuticals to develop next-generation antibody-drug conjugates (ADCs) against a single, undisclosed cancer target. Mersana will combine its Fleximer® conjugation technology with anticancer antibodies discovered by Endo to produce Fleximer-ADC candidates for development, manufacturing and commercialisation by Endo. With this deal, Mersana has emerged as a competitor of Seattle Genetics and ImmunoGen in the development of ADCs.