Treatment with caplacizumab was associated with significant reductions in exacerbations and refractoriness in a real-world immune thrombotic thrombocytopenic purpura (iTTP) population compared with standard-of-care treatment, according to research findings published in Blood Advances. The study was a retrospective analysis of patients with iTTP from the Spanish TTP Registry.
Corresponding author María Eva Mingot-Castellano, MD, PhD, of the Biomedicine Institute of Sevilla in Spain, explained, “Caplacizumab reduces the number of plasma exchange (PEX) and hospital admission days between 30% and 50%, which represents a significant release of not only economic burden, but also human and structural resources. By reducing the number of PEX, the amount of plasma required for donation would decrease and the risk of secondary reactions to plasma, which are very common in these patients, would be reduced.”
The researchers analyzed 77 patients who received the von Willebrand factor (vWF)-directed antibody fragment caplacizumab and 78 who did not. All patients in the study also received PEX and prednisone 1 mg/kg/day or the equivalent dose of corticosteroids, which was referred to as “standard therapy.” Most patients who received caplacizumab or standard therapy also received rituximab (84% and 68%).
The median follow-up periods in the caplacizumab and non-caplacizumab groups were 216 and 214 days, respectively.
Patients who initially received caplacizumab had significantly fewer exacerbations (4.5% vs. 20.5%; p<0.05) and less refractoriness (4.5% vs. 14.1%; p<0.05) compared with those who did not receive caplacizumab.
The time to clinical response was shorter in patients treated with caplacizumab as initial treatment versus those who were not treated with caplacizumab (8.5 vs. 14 days, respectively; p=0.009). Additionally, the time to clinical response after an exacerbation or refractoriness was shorter in patients treated with caplacizumab as initial therapy (five days) compared to patients treated with caplacizumab (15 days; p<0.01).
In multivariate analysis, the use of caplacizumab within the first three days following PEX was associated with a significantly lower number of PEX (p<0.05) and days of hospitalization (p<0.001), compared with standard therapy. There were no severe adverse events in the caplacizumab treatment arm.
In the group of patients who received caplacizumab, there was no difference between the patients who received versus did not receive rituximab in terms of the median time to relapse. “This suggests that rituximab undoubtedly reduces the relapse rate, at least in our series, but it would be important to confirm these findings,” Dr. Mingot-Castellano stated.
A primary limitation of the analysis was its retrospective nature. Dr. Mingot-Castellano noted that in patients who did not receive caplacizumab, there were few data describing the evolution of ADAMTS13 levels, thereby preventing a comparative analysis of its recovery with those that received the therapy.
Any conflicts of interest declared by the authors can be found in the original article.
Pascual Izquierdo MC, Mingot-Castellano ME, Kerguelen Fuentes AE, et al. Real-world effectiveness of caplacizumab vs standard of care in immune thrombotic thrombocytopenic purpura [published online ahead of print, 2022 Aug 5]. Blood Adv. doi: 10.1182/bloodadvances.2022008028.