CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY
WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH
RESPECT TO THE OMITTED PORTIONS.
PATENT RIGHTS PURCHASE AGREEMENT
This Patent Rights Purchase Agreement (this "Agreement") is made and entered into as of December 18, 1998
(the "Effective Date") between Isis Pharmaceuticals, Inc. ("Isis"), and Gilead Sciences, Inc. ("Gilead").
1.1 "Cationic Lipid" means those compounds described in United States Patent Nos. 5,777,153 and 5,705,693;
United States Patent Application Serial No. 08/672,206; and European Patent Application No. 97931462.2, to
the extent such compounds are not Codeblocker Compounds.
1.2 "Codeblocker Compound" means an oligonucleotide that binds directly to DNA or RNA within a cell on a
selective basis determined by the nucleotide sequence of the target DNA or RNA and exerts its biological activity
predominantly through binding to DNA or RNA to inhibit the transcription or replication of the target DNA or
RNA or binding to RNA to inhibit the translation, processing, packaging or regulatory activity of the target RNA.
A Codeblocker Compound may also have a mechanism of action or biological activity other than one conferred
through direct binding to RNA or DNA provided that (i) the compound originally was designed to bind a target
DNA or RNA and (ii) the final compound or any compounds used to derive the final compound were not
identified using selective purification and polymerase amplification in any fashion. An oligonucleotide, is any
oligomer or polymer made up [***] An oligonucleotide includes RNA or DNA fragments, and may be
composed of naturally occurring or non-naturally occurring bases, sugars or intersugar linkages. An
oligonucleotide may have the bases, sugars or intersugar linkages partially or completely absent. Oligonucleotides
may be made such that adjacent nucleoside or nucleoside fragments are linked together by phosphate groups or
modified or non-naturally