Jaktinib Improves Clinical Symptoms in JAK Inhibitor-Naïve Patients With Myelofibrosis

Jaktinib reduces spleen volume and improves anemia and other clinical symptoms with acceptable tolerability in JAK inhibitor-naïve patients with myelofibrosis, according to results from a phase 2 trial published in the American Journal of Hematology.

“Myelofibrosis is associated with several constitutional symptoms. Currently, there are few therapeutic options for myelofibrosis,” wrote Yi Zhang, MD, Department of Hematology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China, and colleagues. “Jaktinib, a novel, small-molecule inhibitor of JAK, is currently being studied for its potential to treat myelofibrosis. This phase 2 trial investigated efficacy and safety of jaktinib in the treatment of myelofibrosis patients.”

The primary end point of the phase 2 trial was the proportion of patients with ≥35% reduction in spleen volume (SVR35, proportion of patients with ≥35% reduction in spleen volume) at week 24. The secondary end points included improvement of anemia, rates of symptom response, and safety profile.

Between January 8, 2019 and August 29, 2020, 118 patients were enrolled in the trial and treated with either jaktinib 100 mg twice daily or 200 mg daily, according to the study. At week 24, 54.8% (34 out of 62) of patients in the 100 mg twice daily group and 31.3% (15 out of 48) in the 200 mg daily group achieved SVR35 (P = .0199).

In addition, jaktinib treatment increased hemoglobin level to ≥20 g/L in 35.6% (21 out of 59) of patients with hemoglobin ≤100 g/L at baseline. The proportion of patients who achieved a ≥50% improvement in total symptom score at week 24 was 69.6% (39 out of 56) in the twice daily group and 57.5% (23/40) in the daily group, the study authors reported.

As for adverse events, the study authors found that the most common grade ≥3 hematological treatment-emergent adverse events (TEAEs; ≥10%) were anemia (100 mg twice daily, 24.2%; 200 mg daily, 28.8%), thrombocytopenia (16.7%; 11.5%), and neutropenia (3%; 11.5%). They found that all non-hematological TEAEs were mild.

“These results indicate that jaktinib can shrink the spleen, improve anemia, and other clinical symptoms with good tolerability,” Zhang and colleagues concluded.

Source:

Zhang Y, Zhou H, Jiang Z, et al. Safety and Efficacy of Jaktinib in the Treatment of Janus Kinase Inhibitor‐Naïve Patients with Myelofibrosis: Results of a Phase II Trial. Am J Hematology. Published online August 28, 2022. doi:10.1002/ajh.26709