DAB389IL2 diphtheria fusion toxin produces clinical responses in tumor stage cutaneous T cell lymphoma.

Four patients with late stage cutaneous T cell lymphoma (IB-IVA) who had failed at least two previous therapies were treated with DAB389IL2 at 9 or 18 microg/kg as 15-min intravenous infusions daily for 5 days every 3 weeks for eight cycles. Mild vascular leak syndrome (VLS) with transient edema, hypoalbuminemia, weight gain, and myalgias was observed in two of the patients lasting 7-10 days and only occurring on the first cycle. One stage IB patient had a pathologic complete remission (CR) lasting 11+ months from treatment initiation, one stage IIB patient had a complete clinical remission (CCR) lasting >6 months with complete clearing of a large tumor lasting >18 months, and one stage IIB and the one stage IVA patient had partial remissions (80-99% reduction in tumor masses) lasting 5 months. While IL2 receptor (IL2R) was expressed on 20-50% of tumor cells prior to therapy, recurrent tumor was IL2R negative in three of the patients. DAB389IL2 at tolerable doses decreased tumor burden in each of these four standard treatment refractory CTCL patients and may offer an important alternative to standard palliative chemotherapy regimens.