Evaluation of a CD5-specific immunotoxin for treatment of acute graft- versus-host disease after allogeneic marrow transplantation

Acute graft-versus-host disease (GVHD) is most often treated with high dose glucocorticoids, but less than half of patients have durable overall improvement. Previous phase I and phase II studies suggested that treatment with a CD5-specific immunotoxin (XomaZyme-CD5 Plus) could ameliorate symptoms of GVHD. In a randomized, double-blind trial, we compared XomaZyme-CD5 Plus and glucocorticoids versus placebo and glucocorticoids as initial therapy for 243 patients who developed acute GVHD after allogeneic marrow transplantation. The study drug (XomaZyme. CD5-Plus or an identical appearing placebo) was administered at a dose of 0.1 mg/kg body weight on each of 14 consecutive days. All patients were treated concomitantly with a standard regimen of methylprednisolone. At the time of entry on study, 94% of patients had a rash, 56% had hyperbilirubinemia, 61% had diarrhea, and 84% had nausea and vomiting. At 3, 4, and 5 weeks after starting treatment, symptom severity was less in the CD5 group than in the placebo group. At 4 weeks, 40% of patients assigned to the CD5 group had complete response compared with 25% of those assigned to the control group (P = .019). At 6 weeks, 44% of patients assigned to the CD5 group had complete response as compared with 38% in the placebo group (P = .36). Clinical extensive chronic GVHD developed in 65% of patients in the CD5 group compared with 72% in the control group (P = .35). Survival at 1 year after treatment was 49% in the CD5 group and 45% in the control group (P = .68). Side effects required close monitoring and appropriate adjustment of treatment. The combined administration of a CD5-specific immunotoxin and glucocorticoids controls GVHD manifestations more effectively than treatment with glucocorticoids alone during the first 5 weeks after starting treatment. Use of this immunotoxin does not result in any long-term clinical benefit for patients with acute GVHD.