This study was an observational study, and about 40 patients with intermediate and high risk myelofibrosis who had participated in any previous clinical study of Gecacitinib hydrochloride and were still receiving Gecacitinib treatment in our center were expected to be enrolled. There was no additional drug intervention, only the myelofibrosis grade and gene mutation level of the patients were collected. Subjects who met all inclusion criteria and none of the exclusion criteria were eligible for inclusion in this study. After informed consent was obtained and screening was successful, bone marrow aspiration, bone marrow biopsy, and gene mutation testing were performed once. If bone marrow was extracted, peripheral blood could be used for gene mutation testing, and then annually until the permanent discontinuation of Gecacitinib.

Previous clinical trials of Gecacitinib hydrochloride tablets in the treatment of myelofibrosis initiated by our center include: 1) ZGJAK002 trial (NCT03886415) : A multicenter phase Ⅱ clinical trial of the safety and efficacy of 100mg BID and 200mg QD of Gecacitinib in the treatment of intermediate and high risk myelofibrosis (n=118). 2) ZGJAK006 study (NCT04217993) : a phase ⅡB clinical trial of the safety and efficacy of gefitinib in Ruxolitinib intolerant myelofibrosis patients (n=51); 3) ZGJAK017 study (NCT04851535) : a phase Ⅱ trial (n=34) to evaluate the efficacy and safety of Gecacitinib in Ruxolitinib refractory or relapsed myelofibrosis patients; 4) ZGJAK016 trial (NCT04617028) : a randomized, double-blind, double-dummy, parallel-controlled, multicenter phase III trial (n=105). At present, the follow-up of the project has ended and the Gecacitinib donation phase has begun.

This study was an observational study, and about 40 patients with intermediate and high risk myelofibrosis who had participated in any previous clinical study of Gecacitinib hydrochloride and were still receiving Gecacitinib treatment in our center were expected to be enrolled. There was no additional drug intervention, only the myelofibrosis grade and gene mutation level of the patients were collected. Subjects who met all inclusion criteria and none of the exclusion criteria were eligible for inclusion in this study. After informed consent was obtained and screening was successful, bone marrow aspiration, bone marrow biopsy, and gene mutation testing were performed once. If bone marrow was extracted, peripheral blood could be used for gene mutation testing, and then annually until the permanent discontinuation of Gecacitinib.

The primary objective was to evaluate the myelofibrosis grade in patients with MF who had previously participated in a clinical study of Gecacitinib and were still receiving gefitinib. The secondary objective was to evaluate the change from baseline in JAK2 isomutations.

Inclusion Criteria:

• They had been enrolled in previous clinical trials of gefitinib for myelofibrosis (ZGJAK002, ZGJAK006, ZGJAK016 and ZGJAK017) and were still receiving gefitinib treatment.
• Comply with the requirements of the ethics committee, voluntarily sign the informed consent.
• Able to adhere to study and follow-up procedures.

Exclusion Criteria:

• Patients with other serious diseases that the researcher believes may affect patient compliance and outcome observation.

This study was an observational study, and about 40 patients with intermediate and high risk myelofibrosis who had participated in any previous clinical study of Gecacitinib hydrochloride and were still receiving Gecacitinib treatment in our center were expected to be enrolled. There was no additional drug intervention, only the myelofibrosis grade and gene mutation level of the patients were collected. Subjects who met all inclusion criteria and none of the exclusion criteria were eligible for inclusion in this study.