TQB3473, a novel spleen tyrosine kinase inhibitor for primary immune thrombocytopenia: a single-arm, open-label, multicenter phase 1 study.
Bingjie Ding, Tiejun Gong, Xiangzhou Du et al.
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In 30 seconds
This single-arm, open-label, multicenter phase 1 study evaluated oral TQB3473 in adults aged 18 to 75 years with relapsed or refractory immune thrombocytopenia at six centers in China. Participants received 400, 600, or 800 mg once daily for 24 weeks. The overall response rate, defined by platelet count reaching at least 50 × 10⁹/L at least once within 12 weeks, was 56.8%; response rates were 0%, 60.7%, and 66.7% across the respective dose groups. The investigators selected 600 mg once daily as the recommended phase 2 dose based on benefit-risk considerations.
Key findings
- Overall response rate was 56.8%; rates were 0% at 400 mg, 60.7% at 600 mg, and 66.7% at 800 mg.
- At 600 mg, the durable response rate was 25%, defined as platelet count ≥ 50 × 10⁹/L in ≥4 of the last 6 visits within 14-24 weeks.
- Treatment-related adverse events occurred in 72.9% of patients and were mostly grade 1 to 2; no thrombotic events or deaths were reported.
- The recommended phase 2 dose was 600 mg once daily, based on the reported benefit-risk profile.
Why it matters
Relapsed or refractory ITP has limited effective treatment options. This early-phase study provides initial evidence of platelet responses with TQB3473 and characterizes treatment-related adverse events, informing further evaluation of the drug. The findings are preliminary and do not establish comparative efficacy or safety against other treatments.
What to keep in mind
The study was single-arm and open-label, with no comparator; its phase 1 design limits conclusions about comparative efficacy and safety.