Hodgkin lymphoma therapy with interleukin-4 receptor-directed cytotoxin in an infiltrating animal model.

Hodgkin lymphoma represents unique clinicopathologic features because Hodgkin and Reed-Sternberg (H-RS) cells produce a variety of cytokines, express a variety of cytokine receptors, and are surrounded by numerous nonmalignant immunoreactive cells. We found that receptors for interleukin-4 (IL-4R) are highly expressed in H-RS cells. To target interleukin-4 receptor (IL-4R), we used a recombinant protein fusing circularly permuted human IL-4 and Pseudomonas exotoxin termed IL4(38-37)-PE38KDEL, or IL-4 cytotoxin. The cytotoxic effect of IL-4 cytotoxin on H-RS cell lines was determined to be moderate to high in vitro. We developed an infiltrating model of Hodgkin disease (HD) by injecting an adherent population of HD-MyZ cells subcutaneously into the flanks of beige/nude/X-linked immunodeficient mice. The animal model exhibited spontaneous metastasis of H-RS cells to lymph nodes and dissemination to vital organs, including the lungs. Intraperitoneal or intratumoral treatment of these mice with IL-4 cytotoxin resulted in regression of the primary tumor mass and a decrease in the incidence of lymph node metastasis. Mice injected with HD-MyZ cells demonstrated 203% prolonged survival (mean survival, 63 days) compared with control (mean survival, 31 days) when they received systemic IL-4 cytotoxin treatment. Because numerous H-RS cell lines express receptors for IL-4, IL-4 cytotoxin may be a unique agent for the treatment of Hodgkin lymphoma.