Real-world effectiveness of caplacizumab vs the standard of care in immune thrombotic thrombocytopenic purpura.

Immune thrombotic thrombocytopenic purpura (iTTP) is a thrombotic microangiopathy caused by anti-ADAMTS13 antibodies. Caplacizumab is approved for adults with an acute episode of iTTP in conjunction with plasma exchange (PEX) and immunosuppression. The objective of this study was to analyze and compare the safety and efficacy of caplacizumab vs the standard of care and assess the effect of the concomitant use of rituximab. A retrospective study from the Spanish TTP Registry of patients treated with caplacizumab vs those who did not receive it was conducted. A total of 155 patients with iTTP (77 caplacizumab, 78 no caplacizumab) were included. Patients initially treated with caplacizumab had fewer exacerbations (4.5% vs 20.5%; P < .05) and less refractoriness (4.5% vs 14.1%; P < .05) than those who were not treated. Time to clinical response was shorter when caplacizumab was used as initial treatment vs caplacizumab used after refractoriness or exacerbation. The multivariate analysis showed that its use in the first 3 days after PEX was associated with a lower number of PEX (odds ratio, 7.5; CI, 2.3-12.7; P < .05) and days of hospitalization (odds ratio, 11.2; CI, 5.6-16.9; P < .001) compared with standard therapy. There was no difference in time to clinical remission in patients treated with caplacizumab compared with the use of rituximab. No severe adverse event was described in the caplacizumab group. In summary, caplacizumab reduced exacerbations and refractoriness compared with standard of care regimens. When administered within the first 3 days after PEX, it also provided a faster clinical response, reducing hospitalization time and the need for PEX.

Influence of glutathione S-transferase T1 donor/recipient mismatch and anti-GSTT1 antibodies in hepatic graft-versus-host-disease.

B cell responses to minor histocompatibility antigens (mHags) have not been extensively studied after allogeneic hematopoietic stem cell transplantation (HSCT). Glutathione S-transferase T1 (GSTT1) is a drug metabolizing enzyme encoded by a single gene that is highly expressed in liver and kidney. Anti-GSTT1 antibodies have been described in the context of antibody-mediated rejection in kidney and liver transplantation, due to a mismatch between donor and recipient. The aim of the present study was to investigate the specific immune response against GSTT1 in HSCT with production of antibodies and their influence in the development of hepatic graft-versus-host-disease (GVHD). Forty patients and their respective donors were included in the study. The median follow-up time was 35.6 months (range 0.6-76 months) and a total of 349 serum samples were tested for the presence of anti-GSTT1 antibodies by ELISA test. Statistical analysis was performed by defining the GSTT1 null donor/positive recipient as mismatch compared with the other three genetic combinations regarded as GSTT1-matched. Antibodies were found in three patients within the group of null donor/positive recipient and one within the null/null group. Development of liver GVHD, particularly its acute form, was highly associated with the GSTT1-mismatch (P=0.0178) and with the presence of post-transplant anti-GSTT1 antibodies (P=0.0076). We conclude that GSTT1 could be considered as a new mHag in hepatic GVHD. The fact that three donors were parous females and the rapid production of antibodies after HSCT suggests the existence in the graft of memory B-cells specific for the GSTT1 antigen.