At the 67th American Society of Hematology (ASH) Annual Meeting (2025 ASH), Chia Tai Tianqing, a core enterprise of Sino Biopharm (1177.HK), presented the latest clinical study data on the Class 1 innovative drug Rovadicitinib (a JAK/ROCK inhibitor) in combination with a BET inhibitor (TQB3617) for the treatment of myelofibrosis (MF) in an oral presentation. In July 2024, the marketing application for Rovadicitinib monotherapy for intermediate- to high-risk MF was accepted by the CDE. The clinical study announced at this annual meeting further explores the therapeutic potential of Rovadicitinib combined with a BET inhibitor, a dual-targeting mechanism. 

Study data^[1] show that this combination therapy achieved a 100% best spleen response rate in JAK inhibitor (JAKi)-naïve patients and a 45% best spleen response rate in patients with a suboptimal response to prior JAKi therapy. It not only fills the clinical treatment gap for patients with a suboptimal response to prior JAKi therapy but also provides a potentially superior solution for treatment-naïve patients, with the potential to reshape the MF treatment landscape. 

Breaking the MF Treatment Dilemma: Domestically Developed JAK/ROCK+BET Combination Shows Its Strength
MF is a BCR-ABL-negative myeloproliferative neoplasm (MPN), which includes primary myelofibrosis (PMF), post-polycythemia vera (PV) myelofibrosis, and post-essential thrombocythemia (ET) myelofibrosis. Clinical manifestations often include a progressive decline in blood cells, hepatosplenomegaly, and systemic constitutional symptoms (such as pyrexia, fatigue, night sweats, weight loss, etc.), with a very high risk of transformation to leukaemia, severely impacting patients' quality of life and survival^[2]. JAK inhibitors (JAKi), which block the JAK-STAT pathway, are the current mainstay of clinical treatment. However, JAKi cannot reverse disease progression, and many patients may develop acquired resistance and experience disease progression again. 

Rovadicitinib (TQ05105) is a First-in-Class (FIC), novel, oral small-molecule JAK/ROCK inhibitor independently developed by Chia Tai Tianqing. At the European Society for Medical Oncology (ESMO) Annual Congress 2024, study data comparing Rovadicitinib with hydroxyurea for the treatment of intermediate- to high-risk MF were presented, showing significant clinical benefit over the control group^[3]. The marketing application for this indication was accepted by the CDE last July, and in August 2025, the indication for chronic graft-versus-host disease (cGVHD) was granted Breakthrough Therapy Designation. TQB3617 is a BET inhibitor with a novel chemical structure independently developed by Chia Tai Tianqing. A Phase I study confirmed that TQB3617 monotherapy is well-tolerated and shows preliminary efficacy in patients with lymphoma^[4]. 

The Phase Ib/II clinical study of Rovadicitinib combined with TQB3617 for the treatment of MF, which was announced this time, is led by the team of Chang Chunkang, Director of the Department of Hematology at Shanghai Sixth People's Hospital, and aims to explore the safety and efficacy of the combination therapy. Key inclusion criteria include: patients aged ≥18 years with primary myelofibrosis (PMF), post-polycythemia vera (PV) myelofibrosis, or post-essential thrombocythemia (ET) myelofibrosis, who are intermediate- to high-risk according to DIPSS and have splenomegaly. 

100% Best Spleen Response Rate in Naïve Patients, New Hope for Refractory Patients

Between December 13, 2023, and June 30, 2025, the Phase Ib and Phase II studies enrolled 12 and 39 patients, respectively, including 36 patients with a suboptimal response to prior JAKi therapy and 15 JAKi-naïve patients. Study results^[1] showed:

● The primary endpoint of Phase Ib was to determine the recommended Phase II dose (RP2D) of the combination therapy; no dose-limiting toxicities (DLTs) were observed. 

● At Week 24, in Phase Ib, 50% (6/12) of patients achieved SVR35 (spleen volume reduction of ≥35% from baseline), 67% (8/12) achieved TSS50 (total symptom score reduction of ≥50%), and 45% (5/11) of patients showed improvement in bone marrow fibrosis grade on biopsy. 

● The primary endpoint of Phase II was the proportion of patients achieving SVR35 (spleen volume reduction of ≥35% from baseline) at Week 24. It included 3 cohorts: Cohorts 1/2 were the two-drug combination for JAKi-naïve MF patients or for patients with a suboptimal response to JAKi, respectively; Cohort 3 was TQB3617 monotherapy for patients with a suboptimal response to JAKi. 

● At Week 24, Cohort 1 (JAKi-naïve group) achieved an SVR35 of 91.67% (11/12) and a TSS50 of 45.45% (5/11); Cohort 2 (prior suboptimal JAKi response group) had an SVR35 of 25% (1/4) and a TSS50 of 100% (4/4). 
Among all enrolled patients, the best spleen response rate for JAKi-naïve patients was 100% (15/15), and for patients with a suboptimal response to prior JAKi therapy, it was 45% (9/20). In patients with baseline anaemia, the mean haemoglobin level increased from a baseline of 84.5 g/L to 109.78 g/L at Week 24. 

In terms of safety, the most common treatment-related adverse events (TRAEs) included thrombocytopenia (56.9%), anaemia (25.5%), lymphopenia (15.7%), leukopenia (11.8%), decreased fibrinogen (11.8%), and hyperuricaemia (11.8%). The incidence of ≥Grade 3 TRAEs was 29.4%, mainly thrombocytopenia (13.7%) and anaemia (5.9%), and no drug-related deaths occurred. 

Chang Chunkang
Principal Investigator (PI) of this study
Director of the Department of Hematology, Shanghai Sixth People's Hospital
Professor and Doctoral Supervisor, Shanghai Jiao Tong University School of Medicine

MF is characterized by the abnormal activation of the JAK-STAT signaling pathway, and elevated inflammatory factors are key drivers of disease progression. Although JAK inhibitor monotherapy is the current standard of care, it cannot fully suppress pro-inflammatory cytokines, highlighting a significant unmet clinical need. BET inhibitors, however, can effectively regulate the release of inflammatory factors. Internationally, the MANIFEST study is already exploring the BET/JAK combination mechanism. Based on this, we have taken the lead in China to conduct clinical exploration of this combination therapy, seeking new breakthroughs for patients with different treatment backgrounds. 

Through the Phase Ib/II clinical study, we observed that Rovadicitinib (a JAK/ROCK inhibitor) combined with TQB3617 (a BET inhibitor) has good efficacy in both JAK inhibitor-naïve and suboptimal response patient populations. For JAK inhibitor-naïve patients, the proportion achieving ≥35% spleen volume reduction (SVR35) at Week 24 was as high as 91.67%, and all naïve patients achieved best spleen response (100%). The symptom score improvement rate (TSS50) reached 45.45%. The data is significantly superior to the efficacy of JAK inhibitor monotherapy, suggesting that combination therapy could become the preferred option for treatment-naïve patients. For refractory patients with a prior suboptimal response to JAK inhibitors, the best spleen response rate for all patients was 45%. Furthermore, a significant improvement in haemoglobin levels was observed in patients with baseline anaemia. 

In summary, this combination therapy has the potential to fill the treatment gap for patients with a suboptimal response to prior JAK inhibitor therapy and provide a better option for treatment-naïve patients, which requires longer-term follow-up for validation. If the results are confirmed, this regimen has the potential to reshape the MF treatment landscape and become a new treatment option for patients of all subtypes. 

References:
[1] Chang Chunkang,et al.Safety and efficacy of the JAK/rock inhibitor Rovadicitinib in combination with the bromodomain and extra-terminal inhibitor TQB3617 in patients with myelofibrosis: A phase Ib/II study.ASH 2025.
[2] MEAD A J, MULLALLY A. Myeloproliferative neoplasm stem cells[J].Blood,2017,129(12):1607-1616.
[3] Chang CK, Zhang M, Gao SJ, et al.Rovadicitinib in Patients with Myelofibrosis Who Were Refractory or Relapsed or Intolerant to Ruxolitinib: A Single Arm, Multicenter, Open-Label, Phase Ib Study.Blood.2024; 144(Supplement 1): 484.
[4] Zhang Yuchen,et al.TQB3617,a bromodomain and extra-terminal inhibitor, in patients with relapsed or refractory lymphoma: A multicenter, phase 1 trial.Med,100893.

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