Second-Line Therapy for Immune Thrombocytopenia: Real-World Experience in Canada

Background The sequence of second-line therapy used for the treatment of immune thrombocytopenia (ITP) is variable. This study aimed to describe the types and sequences of second-line therapies for a large cohort of ITP patients in Canada. Methods We completed a retrospective cohort study of the McMaster ITP Registry. We included patients with primary or secondary ITP who had received one or more second-line therapies including any of the splenectomy, rituximab, danazol, dapsone, or thrombopoietin receptor agonists (TPO-RAs), or immunosuppressant medications. Immunosuppressant medications included azathioprine, cyclophosphamide, cyclosporine, or mycophenolate given alone or in combination. Results We identified 204 ITP patients who had received one or more second-line therapies. The most common second-line therapies were immunosuppressant medications (n = 106; 52.0%), splenectomy (n = 106; 52.0%), TPO-RAs (n = 75; 36.8%), danazol (n = 73; 35.8%), and rituximab (n = 67; 32.8%). For patients who received only one second-line therapy (n = 88), the most common treatment was splenectomy (n = 28; 31.8%). For patients who received more than one second-line therapy (n = 116), the most common treatment sequence was splenectomy, followed by immunosuppressant medications (n = 7; 6.0%). Of the 154 evaluable patients at the end of follow-up, 69 (44.8%) achieved a complete platelet count response and 101 (65.5%) achieved a partial response. Conclusion Immunosuppressant medications and splenectomy are commonly used as second-line therapies for ITP in Canada. Treatment choices and the sequence of treatments were variable.