Brown, who is joining Novartis Oncology in the summer as European head of PR and comms, will be based in the company's European headquarters in Milan.
He joined H&K two years ago from Ruder Finn's healthcare team, where he was an associate director.
At H&K, Brown was responsible for strengthening the agency's existing senior team in the health and wellbeing practice. He was also brought in to implement a ‘healthcare diversification' strategy, working alongside Stuart Smith, chairman of corporate and healthcare.
Brown has spent 16 years in pharmaceutical sales and marketing, including a year with Ruder Finn. Prior to that, Brown worked at pharma firm Pfizer in New York, Europe and the UK. He left his role as a business unit director at Pfizer Animal Health in 2007.
H&K clients include Novartis, which awarded the agency a lucrative animal healthcare brief last year, headed by Brown.
Brown was unavailable for comment as PRWeek went to press.
Last year, Novartis made changes to its senior communications team in the UK.
Director of comms Jason Browning was moved to a role in the pharma company's Switzerland headquarters, where he took up the post of global head of issues and risk communications at Novartis International last September. Sally Irvine took over Browning's role as head of comms.