By Randall Osborne

Protein Design Labs Inc. (PDL) reported positive interim data from a Phase II trial of Zenapax (daclizumab) used with other drugs — but not cyclosporin — for kidney transplantation.

The FDA approved Zenapax late last year based on trials using the drug with immunosuppressant drugs including cyclosporin, a calcineurin inhibitor. (See BioWorld Today, Dec. 12, 1997, p. 1.)

"Cyclosporin, while it can help short-term survival of the graft, can at the same time cause kidney toxicity," said Carol DeGuzman, spokeswoman for Mountain View, Calif.-based PDL.

In the more recent trial, Zenapax was used with CellCept (mycophenolate mofetil), a drug developed by Hoffman-La Roche AG, of Basel, Switzerland, and corticosteroids. Roche also markets Zenapax.

At the 150-day median follow-up, the trial showed 58 percent (57 of 98) of evaluable patients who received successful transplants remained episode free, without requiring a calcineurin inhibitor.

Of the first acute rejection episodes, 80 percent (33 of 41) were successfully treated with corticosteroid therapy. "Some of the physicians elected, later on, to give the patients a calcineurin inhibitor," DeGuzman said.

Median serum creatinine levels (a measure of kidney function) improved in patients who did not receive calcineurin inhibitors, as compared with those who received such drugs in a Phase III trial of Zenapax.

No grafts were lost because of rejection episodes.

Zenapax blocks activated T cells, white blood cells programmed to attack foreign substances, from binding to the new kidney and harming it.

PDL's stock (NASDAQ:PDLI) closed Thursday at $30.593, down $1.90. *