Exhibit 99.2 [Logo of Andersen] Genome Therapeutics Corp. Arthur Andersen LLP 100 Beaver Street Waltham, MA 02453 225 Franklin Street Boston, MA 02110-2812 Tel 617 330 4000 Fax 617 438 8731 www.andersen.com June 18, 2002 To Genome Therapeutics Corp.: We represent that this audit was subject to our quality control system for the U.S. accounting and auditing practice to provide reasonable assurance that the engagement was conducted in compliance with professional standards, that there was appropriate continuity of Arthur Andersen personnel working on the audit, availability of national office consultation, and availability of personnel at foreign affiliates of Arthur Andersen to conduct the relevant portions of the audit. This letter and its contents are intended solely for the internal use of the Company; however, the Company may reveal to third parties that it has received this letter and describe its contents. This letter is not intended to be and should not be used by anyone other than the Company. Very truly yours, Arthur Andersen LLP /s/ Michael G. Donovan By Michael G. Donovan