Successful treatment with Erwinia L-asparaginase for recurrent natural killer/T cell lymphoma.

We describe a patient with natural killer (NK)/T cell lymphoma who relapsed after autologous peripheral blood stem cell transplantation (auto-PBSCT) and was successfully treated with Escherichia coli (E. coli) and Erwinia L-asparaginase. A 38-year-old male patient with ulcerated tumor at the left thigh was diagnosed as having nasal type NK/T cell lymphoma on the basis of histopathological and flowcytometric findings of tumor, revealing diffuse infiltration of atypical lymphoid cells into blood vessels and expression of CD7 and CD56 antigens, but not CD3. He had tumor infiltration in the bone marrow and at the right lower lung field. After five cycles of CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone) therapy, the patient achieved complete remission and received high-dose chemotherapy with auto-PBSCT, although the tumor recurred in the right leg 10 months later. Despite salvage chemotherapy, followed by local irradiation and surgical amputation, a tumor recurred at the left upper gingiva 10 days after. Using E. coli L-asparaginase (6000 U/m2/day), the tumor regressed, fever was alleviated and the serum lactate dehydrogenase decreased to normal range after several days. The asparagine synthetase expression in tumor cells was immunohistochemically negative on paraffin-embedded tissues. Because of the anaphylactoid reaction developing after E. coli L-asparaginase, alternative Erwinia L-asparaginase (6000 U/m2/day) was administered, resulting in regression of tumor and fever lysis. L-asparaginase is a promising agent for the treatment of NK/T cell lymphoma.