When combined with therapeutic plasma exchange (TPE) and immunosuppression, upfront universal administration of caplacizumab was shown to be effective in the management of immune thrombotic thrombocytopenic purpura (iTTP). However, access to this drug remains challenging in many jurisdictions. We retrospectively review results of a single-institution experience with caplacizumab over a 3-year period. During the study period, we treated 48 patients with iTTP, of which 11 (23%) received caplacizumab. Eight of these 11 patients (73%) were female; the median age was 45 years (IQR 37.0-58.5). All received TPE within 24 h of admission (median 9 exchanges, IQR 7.0-12.5), and high-dose steroids. Caplacizumab was initiated for a median of 6 days after admission (IQR 2.5-8.0) and continued for a median of 26 days (IQR 14.0-33.0). Five patients (45%) had refractory disease at caplacizumab initiation. Ten patients (91%) survived, reaching clinical remission. Platelet normalization was reached with a median of 4 days following caplacizumab initiation (IQR 1.5-4.0). Complications included minor bleeding (n = 1) and local allergic reaction (n = 1). No patients experienced TTP exacerbation; relapse occurred in two patients (18%) over 1-5 years of follow-up. Caplacizumab appeared to be effective and safe, despite delayed initiation and in the setting of refractory disease.
Keywords: Canada; caplacizumab; real-world; thrombotic thrombocytopenic purpura.
Immune thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening blood condition characterized by low platelets, anemia, and formation of blood clots in the small blood vessels. The condition results from a patient’s immune system attacking a blood protein called ADAMTS13. The standard treatment for iTTP is plasma exchange (which replaces ADAMTS13) and medications, which suppress the immune system. Recently, a new medication, caplacizumab, has been shown to improve outcomes in iTTP, if combined with a standard treatment. However, this drug is expensive, and not readily available in all parts of the world, including Canada. In this article, we present the first Canadian experience with caplacizumab. Due to its limited access, the drug is frequently used in patients who are refractory to standard treatment or presented with severe organ damage. This contrasts with previously published studies, where it has been used upfront and in all patients with TTP. We find that caplacizumab may be safe and effective in this setting, demonstrating a low mortality rate and rapid recovery in most patients. While upfront and universal use of caplacizumab in the treatment of iTTP is optimal, our approach could be used in settings, where access to this medication is restricted.