Rabbit Antithymocyte Globulin Versus Campath-1H for Treating Severe Aplastic Anemia

Summary

Severe aplastic anemia, characterized by pancytopenia and a hypocellular bone marrow, is effectively treated by immunosuppressive therapy, usually a combination of antithymocyte globulin (ATG) and cyclosporine (CsA). Survival rates following this regimen are equivalent to those achieved with allogeneic stem cells transplantation. However, approximately 1/3 of patients will not show blood count improvement after ATG/CsA. General experience and small pilot studies have suggested that such patients may benefit from further immunosuppression. Furthermore, analysis of our own clinical data suggest that patients with poor blood count responses to a single course of ATG, even when transfusion-independence is achieved, have a markedly worse prognosis than patients with robust hematologic improvement. The management of such cases is uncertain. This study will enroll patients who are either refractory to h-ATG (continued severe pancytopenia) or who have only modest improvement in blood counts (weak hematologic responders) to receive a further immunosuppressive therapy, delivered either as rabbit ATG (Thymoglobulin, r-ATG) or a humanized monoclonal antibody to T-cells, alemtuzumab (Campath-1H ). Primary endpoint will be response rate at 3 months defined as no longer meeting criteria for severe aplastic anemia. Relapse, robustness of hematopoietic recovery at 3 months, survival and clonal evolution to paroxysmal nocturnal hemoglobinuria (PNH), myelodysplasia and acute leukemia will be the secondary endpoints.

Timeline

Start

2003-11-06

Primary completion

2010-12-29

Completion

2016-02-05

Outcome

Missed primary endpoint

paper the response rate for alemtuzumab was 37% (95% confidence interval [CI], 18%-57%) and for rabbit ATG 33% (95% CI, 14%-52%; P = .78). PMID 22067384 ↗

Publications

• Background Young NS, Maciejewski J. The pathophysiology of acquired aplastic anemia. N Engl J Med. 1997 May 8;336(19):1365-72. doi: 10.1056/NEJM199705083361906. No abstract available.
• Background Mathe G, Amiel JL, Schwarzenberg L, Choay J, Trolard P, Schneider M, Hayat M, Schlumberger JR, Jasmin C. Bone marrow graft in man after conditioning by antilymphocytic serum. Br Med J. 1970 Apr 18;2(5702):131-6. doi: 10.1136/bmj.2.5702.131.
• Background Stein RS, Means RT Jr, Krantz SB, Flexner JM, Greer JP. Treatment of aplastic anemia with an investigational antilymphocyte serum prepared in rabbits. Am J Med Sci. 1994 Dec;308(6):338-43. doi: 10.1097/00000441-199412000-00005.
• Scheinberg P, Nunez O, Weinstein B, Scheinberg P, Wu CO, Young NS. Activity of alemtuzumab monotherapy in treatment-naive, relapsed, and refractory severe acquired aplastic anemia. Blood. 2012 Jan 12;119(2):345-54. doi: 10.1182/blood-2011-05-352328. Epub 2011 Nov 8.

Drugs

Indications