Genentech says it has completed its $919 million acquisition of US monoclonal antibody specialist Tanox, which gives the biotechnology gaining access to several drugs, notably the asthma treatment Xolair.

The $20-a-share deal has been cleared by US antitrust authorities, Genentech announced, and the firm now gets full control of Tanox’s stake in Xolair (omalizumab) for asthma, a drug developed in a three-way collaboration between Genentech, Tanox and Novartis. Since July 2003, Genentech has marketed Xolair in the USA, giving Tanox royalties on US sales which rose 14% in the second quarter to $120 million.

Heading Tanox’ development pipeline is TNX-355, which is designed to block the entry of HIV into cells. Unlike other drugs that use this approach, notably Roche’s already-marketed Fuzeon (enfuvirtide), the antibody blocks CD4 receptors, the primary site of HIV binding.