Exhibit 10.1 REGISTRATION RIGHTS AGREEMENT This REGISTRATION RIGHTS AGREEMENT (this "AGREEMENT") is made as of November 19, 1999 by and among (i) Abgenix, Inc., a Delaware corporation (the "COMPANY"), (ii) each person listed on EXHIBIT A attached...Registration Rights Agreement • November 26th, 1999 • Abgenix Inc • Biological products, (no disgnostic substances) • California
