Most patients with early/pre-fibrotic primary myelofibrosis (pre-PMF) and dynamic international prognostic scoring system (DIPSS) low or intermediate-1 risk myelofibrosis (MF) progress to overt PMF or higher risk MF. There is currently no consensus on the optimal treatment strategies in these patients. Ropeginterferon alfa 2b (P1101) is a next generation monopegylated interferon alfa-2b developed specifically to treat myeloproliferative neoplasms (MPN). The P1101MF study is a multicenter phase 2 study of P1101 for patients with pre-PMF and DIPSS low/intermediate-1 risk MF (NCT04988815).