The study is to evaluate the long-term safety and efficacy of P1101 in PV or ET patients who participated in Study A19-201 or Study P1101 ET. The subjects who have completed the 52-week P1101 treatment duration in Study A19-201 will start treatment with P1101 at the dose at Week 50. The subjects who have completed the follow-up/end-of-study visit in Study P1101 ET will start treatment with P1101 at the dose at Week 50. The subjects who were treated with anagrelide will start treatment with P1101 at a dose of 250 μg. The dose of P1101 during this study may be increased or decreased up to 500 μg depending on the condition.~Evaluation of safety will include assessing vital signs, clinical safety laboratory tests, physical examinations, ECG evaluation, heart ECHO, lung X-ray, ECOG performance status, ocular examination, and AEs.~Efficacy evaluations, safety assessments, and immunogenicity evaluations of P1101 will be performed.~Evaluation of efficacy will include clinical laboratory assessments, allelic burden measurements of CALR, JAK-2, and MPL, spleen size measurements, bone marrow sampling.
This is a Phase 3 open-label, multicenter, single arm study designed to evaluate the efficacy and safety and tolerability of P1101 patient with PV or ET in long-term.