Eligible subjects will be treated with P1101 at a starting dose of 250 µg at Week 0, a medium dose of 350 µg at Week 2, a target dose of 500 µg at Week 4, and a maintenance dose of 500 µg from the subsequent week until Week 52. At Week 24 (Month 6), the primary study endpoint, i.e., the phlebotomy- or erythrocytapheresis-free CHR rate, will be analyzed.~For subjects who switch from previous HU treatment to P1101 (for subjects who are currently receiving HU treatment), the dose should be gradually reduced during the screening period (adjusted by the investigator based on clinical practice); the HU treatment should be ended within up to 4 weeks of P1101 treatment, and HU should be prohibited after 4 weeks of P1101 treatment.~During the treatment period, subject visits are scheduled for once every 2 weeks. The end of treatment (EOT) visit will be performed at Week 52 or early termination of the study, and the end of study (EOS) visit will be performed at 28 days after the EOT visit.~Data analyses will be performed after all subjects complete 24 weeks of treatment, and a clinical trial report written, and the new drug application is submitted accordingly. An end-of-study statistical analysis will be performed after all the subjects have completed all visits as per protocol.
This study is a phase II single-arm study designed to evaluate the efficacy and safety of P1101 in Chinese PV patients who are intolerance or resistance to HU.