***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Severe acquired aplastic anaemia ( SAA ) is a life-threatening disease characterized by pancytopenia and hypoplastic bone marrow . Autologous T lymphocytes are thought to cause bone marrow failure by immune-mediated excessive apoptosis of stem and progenitor cells . The disease is subclassified into a severe ( neutrophil count , > 0.2 x 10(9)/L [ > 200/microL ] ) and a very severe ( < 0.2 x 10(9)/L [ < 200/microL ] ) ( vSAA ) form . We report the results of a prospect i ve multicenter trial with a combined immunosuppressive regimen of cyclosporin A ( CSA ) , anti-thymocyte globulin ( ATG ) and , in cases with neutrophil counts fewer than 0.5 x 10(9)/L ( < 500/microL ) , granulocyte colony-stimulating factor ( G-CSF ) for treatment of SAA in children . Children with vSAA showed a higher rate of complete response than did children with SAA ( 68 % versus 45 % ; P = .009 ) , as well as better survival ( 93 % versus 81 % ; P < .001 ) . Thus , in children with SAA a more severe disease stage at diagnosis indicates a favorable outcome with immunosuppressive therapy BACKGROUND In severe acquired aplastic anemia , hematopoietic failure is the result of immune-mediated destruction of bone marrow stem and progenitor cells . Immunosuppressive therapy with antithymocyte globulin ( ATG ) plus cyclosporine is an effective alternative to stem-cell transplantation and improves blood counts and survival . Although horse ATG is the st and ard therapy , rabbit ATG is more potent in depleting peripheral-blood lymphocytes and is preferred in other clinical circumstances . METHODS From December 2005 through July 2010 , we performed a r and omized trial comparing these two ATG formulations in conventional regimens . Patients were treated at a single facility . The primary outcome was hematologic response at 6 months , as determined by blood counts . The study was design ed to enroll 60 patients each for the rabbit-ATG and horse-ATG groups and was powered to detect a difference of 25 percentage points in the response rate . RESULTS A large , unexpected difference was observed in the rate of hematologic response at 6 months in favor of horse ATG ( 68 % ; 95 % confidence interval [ CI ] , 56 to 80 ) as compared with rabbit ATG ( 37 % ; 95 % CI , 24 to 49 ; P<0.001 ) . Overall survival at 3 years also differed , with a survival rate of 96 % ( 95 % CI , 90 to 100 ) in the horse-ATG group as compared with 76 % ( 95 % CI , 61 to 95 ) in the rabbit-ATG group ( P=0.04 ) when data were censored at the time of stem-cell transplantation , and 94 % ( 95 % CI , 88 to 100 ) as compared with 70 % ( 95 % CI , 56 to 86 ; P=0.008 ) in the respective groups when stem-cell-transplantation events were not censored . CONCLUSIONS In a r and omized study , rabbit ATG was inferior to horse ATG as a first treatment for severe aplastic anemia , as indicated by hematologic response and survival . ( Funded by the Intramural Research Program of the National Institutes of Health ; Clinical Trials.gov number , NCT00260689 . ) Aplastic anemia ( AA ) is a rare , life threatening disease . Allogeneic bone marrow transplantation ( BMT ) offers the only possibility of cure , i. e. life-long remission . The probability of survival after BMT from an HLA-identical sibling has clearly improved over the last years and at present is about 80 % in patients < 16 years .  Transplantation from alternative donors , however , faces unsolved immunological problems . For demographic reasons most patients lack a matched sibling donor . For these patients immunosuppressive therapy ( IST ) is the only alternative therapeutic approach . However this treatment has frequently result ed in clonal , i. e. potentially malignant disease . Overall probability of survival here is only 50 % , in severely granulocytopenic patients ( < 0.2 G/l ) even lower . These individuals represent an important subgroup in pediatric AA . Some patients show only partial reconstitution of their hematopoiesis but satisfactory quality of life . Based on the results of prospect i ve studies a protocol for IST in AA using anti-lymphocyte globulin ( ALG ) , cyclosporin A ( CSA ) and G-CSF is presented . For BMT- patients likewise a protocol for conditioning ( ALG , cyclophosphamide ) and GvHD-prophylaxis is suggested . St and ardisation and improvement of supportive therapy is the third important objective of this pilot protocol 58 patients with severe aplastic anemia ( SAA ) were treated and evaluated in a prospect i ve study either by bone marrow transplantation ( BMT ) or by  antilymphocyte globulin ( ALG ) . 19 patients were treated with BMT ; 9 are still alive 6 months to 5 years after BMT ( 47 % ) . 39 patients were treated with  ALG ; 28 are alive 5 months to 5 years after ALG ( 72 % ) . 24 of these 28 are self-sustaining and in remission . The results show that treatment with ALG is probably superior to treatment with  BMT  , and also demonstrate that most patients with SAA have a pool of hematopoietic stem cells able to repopulate the marrow after this type of treatment 
    Output:
    
There are insufficient and biased data that do not allow any firm conclusions to be made about the comparative effectiveness of first-line allogeneic haematopoietic stem cell transplantation of HLA-matched sibling donors and first-line immunosuppressive therapy of patients with acquired severe aplastic anaemia