SOUTH SAN FRANCISCO, Calif. (AP) — Genentech Inc. said Tuesday the U.S. Patent and Trademark Office confirmed the validity of a crucial patent covering ways the biotechnology company makes certain of its drugs. The Cabilly patent covers certain methods used to make antibodies and antibody fragments by recombinant DNA technology, as well as cells and DNA used in those methods. Genentech uses this technology for many of its own products and receives revenue from licensing it to other companies. The Patent Office reexamined the patent at the behest of third parties who filed their request in 2005. In February 2008, the Patent Office rejected the patent, but Genentech appealed that ruling. Genentech said the latest decision on the so-called Cabilly patent is final and unappealable. The patent is co-owned by City of Hope, a biomedical research firm and hospital in Duarte, Calif.