Looking to build its presence within the ADC space, GSK has entered into an option agreement with Mersana Therapeutics to co-develop and commercialise the latter’s candidate, XMT-2056. This drug is an Immunosynthen stimulator of interferon genes (STING) agonist antibody-drug conjugate (ADC) that targets an epitope of human epidermal growth factor receptor 2 (HER2). The deal, worth up to US$1.464 B, provides Mersana with further validation of its ADC technologies and allows GSK to strengthen its ADC pipeline, which is currently lead by its marketed anti-B cell maturation antigen (anti-BCMA) therapy, Blenrep® (belantamab mafodotin-blmf).