IMMUNEX - PROGRESS THROUGH PATENTS

Although Immunex has developed a large patent portfolio, this has not secured the company a substantial stream of sales or licensing income. The Company's main recombinant product, based on granulocyte macropha ge-colony stimulating factor (GM-CSF), is the subject of patent interf erence proceedings. In addition, several of its products that are curr ently in development are based on interleukins (ILs), one of the most heavily patented areas in biotechnology. Developing successful drugs b ased on recombinant human proteins is highly dependent on strong paten t protection. The Company's merger with a subsidiary of American Cyana mid and the subsequent equity acquisition by American Home Products ha ve helped the Company to reduce its financial losses. Whether this sup port will translate into more successful product development remains t o be seen.