This Agreement (together with the Confidentiality Agreement entered into by and between the Company and the Gilead Group on the date hereof) contains the entire understanding of the parties with respect to the subject matter hereof (notwithstanding any other agreements, promises, representations, warranties, covenants or other undertakings, whether written or oral) and may be amended only by an agreement in writing executed by the parties hereto. No rights under this Agreement shall be deemed waived absent a written waiver by the party granting the waiver.