Successful treatment of refractory metastatic histiocytic sarcoma with alemtuzumab.

BACKGROUND

Histiocytic sarcoma (HS) is an exceedingly rare tumor and carries a dismal prognosis when patients present with advanced-stage disease. Because of the poor response rates to conventional chemotherapy and the rarity of the disease, no standard of care exists for patients with HS. The authors report the single-agent use of the anti-CD52 antibody alemtuzumab in 2 patients who had advanced-stage HS.

METHODS

Two patients with chemotherapy-refractory, metastatic HS with tumors that expressed the CD52 antigen received a prolonged course of treatment with the anti-CD52 monoclonal antibody alemtuzumab.

RESULTS

Resected tumor samples from both patients demonstrated CD52 expression. Both patients had marked responses to single-agent alemtuzumab. One patient had a complete response with no evidence of disease for >5 years. The second patient had a major response to alemtuzumab and also remained alive with no evidence of disease for >4 years.

CONCLUSIONS

Further studies need to be performed to examine CD52 expression and function in HS as well as the role of alemtuzumab in a larger cohort of patients. However, the clinical impact of single-agent alemtuzumab in the 2 patients described in this report was very encouraging. Given the toxicity and frequent inefficacy of conventional chemotherapy, patients with incompletely resected HS should be strongly considered for alemtuzumab therapy.