Alemtuzumab and Low-Dose Cyclosporine in Treating Patients With Severe Aplastic Anemia or Acquired Marrow Failure

DISEASE CHARACTERISTICS:

* Diagnosis of 1 of the following:

  * Severe or very severe aplastic anemia, as defined by the following criteria:

    * Meets ≥ 2 of the following criteria:

      * Absolute neutrophil count \< 0.5 x 10\^9/L (severe) or \< 0.2 x 10\^9/L (very severe)
      * Platelet count \< 20 x 10\^9/L
      * Reticulocyte count \< 20 x 10\^9/L
    * Hypocellular bone marrow (\< 30% cellularity) without evidence of fibrosis or malignant cells
  * Single lineage acquired marrow failure (e.g., pure red cell aplasia, agranulocytosis, amegakaryocytic thrombocytopenia)
* Paroxysmal nocturnal hemoglobinuria clone allowed
* Failed first-line therapy with antithymocyte globulin (ATG) and cyclosporine OR not eligible for ATG-based studies

  * Failure is defined as lack of hematological response, requirement for chronic immunosuppressive treatment to sustain response, or relapse
* Not eligible for a low-risk stem cell transplantation
* No evidence of risky myelodysplastic syndromes (i.e., IPSS 3-4), as defined by the presence of marrow blast excess or karyotypic abnormalities, or other primitive marrow disease
* No history of constitutional aplastic anemia (e.g., Fanconi anemia or dyskeratosis congenita)

PATIENT CHARACTERISTICS:

* WHO performance status 0-2
* Not pregnant or nursing
* No active malignant tumor within the past 5 years
* Transaminases ≤ 3 times upper limit of normal (ULN)
* Albumin ≥ 1.5 g/L
* Creatinine ≤ 3 times ULN
* No CMV viremia, as defined by positive PCR or pp65 test
* No cardiac failure (i.e., ejection fraction \< 35%)
* No other concurrent life-threatening disease (including HIV infection)

PRIOR CONCURRENT THERAPY:

* No prior allogeneic stem cell transplantation
* At least 2 weeks since prior cyclosporine or filgrastim (G-CSF)