Prof Jean-Jacques Kiladjian discusses the ongoing phase III ROP-ET study evaluating ropeginterferon alfa-2b in patients with essential thrombocythemia who are intolerant, resistant, or ineligible for standard cytoreductive therapies. He outlines the unmet need in this population, the study design and endpoints, and the favourable tolerability observed to date ahead of the planned 12-month primary efficacy analysis.