Xencor Inc., a Monrovia company developing antibody-based drugs to treat cancer, autoimmune diseases and other conditions, filed for an initial public offering on Friday. The company, which does not yet have any drugs on the market, said it hopes to raise up to $69 million in the IPO. It plans to list on the Nasdaq under the symbol XNCR. Xencor was founded in 1997 and is led by Chief Executive Bassil Dahiyat. It recorded $9 million in collaboration revenue for the 12 months ended June 30. Corporate partners include Amgen Inc., Pfizer Inc. and Boehringer Ingelheim. The company said net proceeds from the offering will pay for mid-stage clinical study for an autoimmune treatment and an early-stage study of an asthma therapy. Amgen, based in Thousand Oaks, has licensed an option to commercialize the autoimmune drug if trial results pan out. Xencor’s venture backers include MedImmune Ventures, HealthCare Ventures, and John R. Stafford III.