New Treatment for NonHodgkin's Lymphoma

In vitro and in vivo studies have shown that a cytotoxic ribonuclease linked to the anti-CD22 monoclonal antibody (RFB4) can significantly prolong survival in mice with severe combined immunodeficiency disease (SCID). The studies were presented at the Fifth International Symposium on Predictive Oncology and Therapy, in Geneva, Switzerland.

The anti-CD22 antibody conjugate, called Onconase, specifically targets and kills CD22 positive human lymphoma cells. In the studies, the SCID mice were intravenously transplanted with the most aggressive form of human lymphoma (Burkett's type ) cells. Survival of the conjugate-treated animals was significantly prolonged, by 135%, compared to control animals. The mice tolerated doses of conjugate as high as 400 mg/kg of body weight, much higher than those of other immunotoxins. Thus, relatively high doses of conjugate could be delivered with repeated systemic administration, producing a significant survival benefit. The conjugate did not inhibit protein synthesis of human umbilical vein endothelial cells, suggesting that it may not cause vascular leak syndrome, the most dreaded complication of previous immunotoxin therapies.

Onconase is the product of Alfacell Corp. (Bloomfield, NJ, USA) and is currently being investigated in phase III human clinical trials in patients with unresectable malignant mesothelioma. To date, more than 700 patients with a variety of solid tumors have been treated. "Alfacell has long recognized the potential of Onconase as an effective and relatively safe anticancer agent, both as a single agent and in combination with other therapies,” noted Stan Mikulski, M.D., medical director and executive vice president of Alfacell.



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