Cialis Filed in European Union for Once-a-Day Dosing for Erectile Dysfunction; ICOS Expects Significant Acceleration of Earnings in 2007 and 2008

"We are very excited about the prospect of bringing CialisOnce-A-Day to the market in North America and Europe," stated PaulClark, ICOS Chairman and CEO. "Market research revealed thatonce-a-day therapy could especially appeal to an important segment ofthe patient population -- the man in his forties or fifties who takesa PDE5 inhibitor more frequently than average."

Mr. Clark added, "Importantly, growth in worldwide Cialis sales,including Cialis Once-A-Day beginning in 2008 if approved, areexpected to drive accelerated earnings for ICOS Corporation."

The recent EMEA filing followed the completion of three Phase 3clinical studies that evaluated the efficacy and safety of Cialis whenadministered once-a-day for the treatment of ED. Men with ED takingCialis 5 mg Once-A-Day experienced significantly improved erectilefunction compared to those taking placebo. Cialis 5 mg Once-A-Day wasgenerally well-tolerated with most frequently occurring side effectsbeing upset stomach and headache.

"Introducing the once-a-day treatment for ED is part of our longrange strategic plan for maximizing the value of the tadalafilmolecule," added Leonard Blum, Senior Vice President, Sales andMarketing. "The once-a-day dose would be priced less than the Cialis10 mg or 20 mg tablet, commonly used on-demand and, as a result, couldbe a financially viable alternative to the current on-demand regimen."

Financial Outlook

In order to provide some context as to the potential value ofCialis Once-A-Day, ICOS is presenting its expectations for futureresults. ICOS is assuming that Cialis Once-A-Day will be approved inthe United States, Europe, Canada and Mexico, and will generateincremental sales beginning in 2008.

On May 4, 2006, ICOS stated its expectation that 2006 worldwideCialis product sales would be around $900 million, and Lilly ICOS'2006 net income would be near the upper end of the $210 million to$240 million range previously communicated. The Company also indicatedthat it expected ICOS' 2006 full year GAAP net loss to be near the lowend of the $5.0 million ($0.08 per share) to $25.0 million ($0.39 pershare) net loss range that it had previously communicated.

"We are delighted to discuss, for the first time, our expectedsignificant acceleration of earnings for ICOS Corporation in 2007 and2008," said Michael Stein, Senior Vice President and Chief FinancialOfficer.

ICOS Corporation currently expects its 2007 fully-taxed net incometo be in the range of $35 million ($0.53 per diluted share) to $45million ($0.68 per diluted share). For 2008, ICOS Corporation'sfully-taxed net income is presently expected to be in the range of $85million ($1.23 per diluted share) to $100 million ($1.45 per dilutedshare).

The expected 2007 and 2008 results of operations for ICOSCorporation are presented on a fully-taxed basis, assuming a 35%effective income tax rate. However, because of net operating losscarryforwards, the Company does not expect that ICOS Corporation willrecognize or pay significant Federal income taxes in those years.

ICOS anticipates that 2007 worldwide Cialis product net sales maygrow at or greater than a mid-teens percentage rate, to in excess of$1 billion, and expects a greater than 50% increase in Lilly ICOS'2007 net income compared to 2006.

ICOS expects that 2008 worldwide total Cialis net product sales(including once-a-day) may grow 20% to 25% over 2007, and expects a40% to 50% increase in Lilly ICOS' net income in 2008 compared to2007.

Expected results for Lilly ICOS do not include any costs it mightchoose to incur as a result of a successful outcome of the currentlyin process Phase 2 study of tadalafil in hypertension.

Conference Call

ICOS will host a conference call, on Thursday, June 8, 2006, at8:30 a.m. Eastern Time, to discuss plans for Cialis Once-A-Day andrelated matters, including information regarding expected futureresults of operations. The conference call can be accessed as awebcast at www.icos.com, in the Investor/Events section, or bytelephone, using the Passcode 832207, live at 480-629-9025, or as areplay at 320-365-3844. The webcast will be available until June 15,2006, at 9:30 a.m. Eastern Time. The telephone replay will beavailable until June 9, 2006, at 8:00 p.m. Eastern Time.

About ED

ED is defined as the consistent inability to attain and maintainan erection sufficient for sexual intercourse. ED affects an estimated189 million men worldwide(1). Experts believe that 80-90 percent of EDcases are related to a physical or medical condition, like diabetes,cardiovascular diseases, and prostate cancer treatment, while 10-20percent are due to psychological causes(2)(3). In many cases, however,both psychological and physical factors contribute to thecondition(4).

About Cialis

Cialis(R) (tadalafil) is approved for the treatment of erectiledysfunction, and is the only oral ED tablet clinically proven to workup to 36 hours. Cialis is available by prescription only and is notfor everyone. Men taking nitrates, often used for chest pain, shouldnot take Cialis. Such a combination could cause a sudden, unsafe dropin blood pressure. The most common side effects with Cialis wereheadache, upset stomach, delayed backache or muscle ache. As with anyED tablet, in the rare event of priapism (an erection lasting morethan four hours), men should seek immediate medical attention to avoidlong-term injury. Men should not drink alcohol in excess with Cialis.

Cialis does not protect a man or his partner from sexuallytransmitted diseases, including HIV. In rare instances, men takingprescription ED tablets (including Cialis) reported a sudden decreaseor loss of vision. It's not possible to determine if these events arerelated directly to the ED tablets or to other factors. If a man has asudden decrease or loss of vision, he should stop taking any ED tabletand seek immediate medical attention. Men should discuss their medicalconditions and all medications with their doctors to ensure Cialis isright for them and that they are healthy enough for sexual activity.

Individual results may vary. Cialis has not been studied formultiple attempts per dose. For full patient information and/or fullprescribing information, visit http://www.cialis.com.

Tadalafil, the active ingredient in Cialis, is also beingevaluated for other medical conditions, such as hypertension, benignprostatic hyperplasia (BPH) and pulmonary arterial hypertension (PAH).

About ICOS Corporation

ICOS Corporation, a biotechnology company headquartered inBothell, Washington, is dedicated to bringing innovative therapeuticsto patients. ICOS is working to develop treatments for serious unmetmedical conditions such as benign prostatic hyperplasia, hypertension,pulmonary arterial hypertension, cancer and inflammatory diseases.Additional information about ICOS is available at www.icos.com.

Except for historical information contained herein, this pressrelease contains forward-looking statements within the meaning of thePrivate Securities Litigation Reform Act of 1995, including statementsconcerning anticipated regulatory approvals of once-a-day dosing ofCialis and expected future results of operations. In some cases, youcan identify forward-looking statements by terminology such as"anticipate," "believe," "continue," "could," "estimate," "expect,""intend," "may," "might," "plan," "possible," "potential," "predict,""should" or "will" or the negative of such terms or other comparableterminology. Forward-looking statements are only predictions thatprovide our current expectations or forecasts of future events. Theseforward-looking statements involve risks and uncertainties that maycause our results and the timing and outcome of events to differmaterially from those expressed in or implied by the forward-lookingstatements, including risks associated with product commercialization,research and clinical development, regulatory approvals,manufacturing, collaboration arrangements, liquidity, competition,intellectual property claims, litigation and other risks detailed inour latest Quarterly Report on Form 10-Q and our other public filingswith the Securities and Exchange Commission. In particular, governmentregulatory authorities may not approve once-a-day dosing of Cialis ormay delay its approval. Any failure to receive the regulatoryapprovals necessary to commercialize once-a-day dosing of Cialis couldharm our business. Human therapeutic products are subject to extensiveand rigorous government regulation. In addition, we have only limitedexperience in filing and pursuing applications necessary to gainregulatory approvals, which may impede our ability to obtain suchapprovals. The regulatory review and approval process is lengthy,expensive and uncertain. Any FDA or other regulatory approval of ourproduct candidates, once obtained, may be withdrawn.

Any or all of our forward-looking statements in this press releaseand in any other public statements that we make may turn out to bewrong. Inaccurate assumptions we might make and known and unknownrisks, uncertainties and other factors may cause our actual results,performance or achievements to be materially different from any futureresults, performance or achievements expressed or implied by suchforward-looking statements. Although we believe that the expectationsreflected in the forward-looking statements are reasonable, based onthe information available to us at the time the statements are made,we cannot guarantee future results, performance or achievements. Youshould not place undue reliance on these forward-looking statements.

The forward-looking statements contained in this press releaserepresent our judgment as of the date of this release. Except asrequired under federal securities laws and regulations, we undertakeno obligation to publicly update any forward-looking statements,whether as a result of new information, future events or otherwise.The biotechnology and pharmaceutical businesses are risky and therecan be no assurance that any of our products or product candidateswill achieve commercial success or that competing therapies will notpre-empt market opportunities that might exist for any of our productsor product candidates.

(1)Data were extrapolated from Feldman HA, Goldstein I,Hatzichristou DG, Krane RJ. Impotence and its Medical and PsychosocialCorrelates: Results of the Massachusetts Male Aging Study, Journal ofUrology. Vol. 151, 54-61, January 1994 and World Population ProjectionProgram Of United Nations (2002 Revision) with indirectstandardization.

(2)Shabsigh, R. (2002). Back To Great Sex: Overcome ED and ReclaimLost Intimacy. New York: Kensington.

(3)Diseases and Conditions: Impotence,http://www.impotence.org/FAQ/index.asp. Data accessed 11.20.03

(4)Lue, Tom F. Erectile Dysfunction. N Engl J Med 2000; 342:1802-1813.