Alfacell has announced that over 300 patients are now enrolled in the company's international, confirmatory Phase IIIb trial evaluating Onconase (ranpirnase), the company's lead investigational drug candidate, as a treatment for unresectable malignant mesothelioma. The required number of patients for full enrollment is 316.

Onconase is a ribonuclease protein that enhances the anticancer effects of conventional chemotherapy. Normally, the body pumps out anticancer drugs from the cancerous cell, requiring that higher doses of the toxic drugs be used. Other studies have suggested that Onconase is able to make these resistant cells susceptible to standard levels of treatment so that lower doses are effective and side effects are reduced.