• 2/17/2005
  • Yael Waknine
  • Medscape (www.medscape.com)

Orphan Drug (Proxinium) for Advanced, Recurrent Head and Neck Cancer

On Feb. 3, the FDA approved orphan drug status for Proxinium (formerly known as VB4-845, made by Viventia Biotech, Inc.), allowing its use in the treatment of advanced, recurrent head and neck cancer. The product is intended to target tumor cells while avoiding healthy tissue.

Proxinium is made up of a humanized single-chain antibody fragment recombinantly fused with a protein cytotoxic agent. The antibody fragment binds to an epithelial cell surface antigen found on the surface of most head and neck tumor cells, allowing its internalization and delivery of the cytotoxic component.

The approval was based on the results of a phase 1 trial showing that treatment with Proxinium yielded an objective response rate of 43% in 14 patients with progressive disease. All patients had head and neck tumors expressing the target antigen and a majority had failed prior courses of chemotherapy and/or radiotherapy.

Of the 14 patients, tumor regression was significant in two patients and minor in four others. In an additional four patients, their disease stabilized after treatment. Tumor growth control was therefore achieved in 71% of treated lesions.

Treatment-related adverse events were mild, such as injection-site pain.

A second phase-1 trial is currently under way to assess the safety and tolerability of the product using a more intensive dosing schedule than that previously studied. The product is also being evaluated for use in bladder cancer.