Alemtuzumab Treatment for Aplastic Anemia (AA) and Low-Risk Myelodysplastic Syndrome (MDS): Preliminary Results.

We investigated the effectiveness of systemic immunosuppressive treatment using alemtuzumab (MabCampath®, Schering, Berilin, Germany) in adult patients with AA and low-risk MDS. This prospective study began on September 2005 and 11 patients, 7 severe AA and 4 MDS (RA 2, RCMD 1, RCMD-RS 1), have been enrolled onto the study. Patients received a total of 101 mg of alemtuzumab for 11 days: a test dose of 1 mg on the first day and a daily dose of 10 mg for the next 10 consecutive days. Anti-infective prophylaxis including ciprofloxacin, acyclovir, and bactrim was given for 8 weeks. One patient died of cerebral hemorrhage on 22 days after alemtuzumab treatment and another patient was lost to follow-up 123 days after the treatment. Nine patients are surviving with a median follow-up duration of 366 days. Non-hematologic toxicities were mild and transient: infusional fever/chill in 5 (grade I in all), skin rash in 2 (grade I in both), and increase of liver enzymes in 4 (grade I in all). Patients experienced transient aggravation of pancytopenia. One patient showed severe thrombocytopenia that was refractory to platelet transfusion leading to fatal cerebral hemorrhage. Lymphocyte subset analyses showed that B cells and natural killer cells recovered by 6 months, but CD4+ or CD8+ T cells remained at low levels for more than 6 months. There was no serious opportunistic infection requiring hospitalization. Three patients (27.3%) showed hematologic response to alemtuzumab treatment: partial response in 2 and complete response in one. Two partial responses occurred on 50 days (in an 18 year-old female with AA) and 157 days (in a 50 year-old male with RCMD-RS) after alemtuzumab treatment, but response duration was short in both patients (231 days and 51 days, respectively). In a 25 year-old male with RA, hematologic response occurred on 83 days after alemtuzumab treatment and complete response was attained on 237 days after the treatment. He remained in complete hematologic response on 370 days after the treatment. Our preliminary results showed that alemtuzumab treatment might be effective in some patients with AA and low-risk MDS, but hematologic response rate seemed low. This study will continue with the patients who are unresponsive to standard immunosuppressive treatment with ATG plus cyclosporine and are ineligible for allogeneic hematopoietic cell transplantation.