Treatment of refractory peripheral T-cell lymphoma with denileukin diftitox (ONTAK).

Peripheral T-cell lymphomas (PTCLs) are an uncommon and heterogeneous group of well-differentiated, post-thymic T-cell malignancies that can present in the skin as cutaneous T-cell lymphomas. In general, their prognosis is poor, and specific therapy is not well defined. We report the successful treatment of a patient with relapsed, refractory PTCL who after failing 13 standard single and multiple chemotherapy regimens and experimental agents had a dramatic prolonged response to diftitoxin denileukin (ONTAK). This fusion protein, composed of diphtheria toxin coupled to interleukin-2, is approved for cutaneous T-cell lymphomas, including mycosis fungoides, and should be considered for treatment of the rare subset of peripheral T-cell lymphomas.