Pfizer Inc., the world's largest drugmaker, may pay Incyte Corp. as much as $803 million for rights to experimental medicines against diseases including rheumatoid arthritis. Incyte shares rose 22 percent on the news yesterday. Incyte will receive an initial payment of $40 million for the worldwide development and marketing rights to its portfolio of CCR2 antagonist compounds, the companies said in a statement yesterday. Incyte will be eligible for additional payments of as much as $743 million as well as royalties on drug sales. Pfizer will also buy $20 million in convertible notes from Incyte.