OSI Pharmaceuticals Summarizes Macugen(R) (pegaptanib sodium injection) Data Presented at Association for Research in Vision and Ophthalmology (ARVO) Meeting

OSI Pharmaceuticals, Inc. (NASDAQ: OSIP) today providedan informational update summarizing highlights from presentations maderegarding Macugen(R) (pegaptanib sodium injection) at this year'sAssociation for Research in Vision and Ophthalmology (ARVO) annualmeeting held from April 30 to May 4 in Fort Lauderdale, Florida. Twopreliminary studies that examine the sequential use of a non-selectiveanti-VEGF (vascular endothelial growth factor) therapy followed byMacugen therapy to address long-term safety and clinical benefitconsiderations for patients with neovascular age-related maculardegeneration (AMD) showed promising indications of activity. Anotherstudy provides support to the hypothesis that Macugen may be moreeffective as primary therapy in neovascular AMD patients with earlylesions. Additional presentations included studies of Medicare data,which show that patients over age 65 with neovascular AMD havesignificantly more co-morbid conditions such as hypertension,diabetes, lipid disorders, stroke and heart attack, compared to thosewho do not have neovascular AMD. Promising early data demonstratingthe potential utility of Macugen in the treatment of diabeticretinopathy, a common debilitating complication of diabetes that canlead to blindness, was also presented.

Following are summaries of select presentations:

Sequential Use of Macugen with Non-selective Anti-VEGF Therapies

Intravitreal Bevacizumab (Avastin(R)) Enhanced Pegaptanib(Macugen) Therapy for Choroidal Neovascularization in AMD: An AvastinBooster, presented by Michael Tolentino, MD, Center for Retina andMacular Disease, FL.

-- Twenty-six eyes of 26 patients received one intravitreal injection of Macugen for neovascular AMD, followed two to three weeks later by one intravitreal injection of bevacizumab (Avastin) and at least two subsequent injections of Macugen. Gains or loss of lines on Snellen acuity between vision prior to Avastin injection and vision prior to the third Macugen injection was used as the primary endpoint.

-- 9/26 (34.6 percent) eyes gained three lines or more of vision, 18/26 (69.2 percent) eyes gained one or more lines of vision, 5/26 (19.2 percent) eyes had stable vision, and 3/26 (11.5 percent) eyes lost one or more lines of vision.

Safety and Efficacy of Combined Pegaptanib/BevacizumabIntravitreal Injection as a Treatment for Age-Related MacularDegeneration, presented by Mark Hughes, MD, Ophthalmic Consultants ofBoston.

-- Twenty patients with a cross section of angiographic subtypes of neovascular AMD were treated with Avastin followed by Macugen. All had one intravitreal injection of Avastin followed by four Macugen injections every six weeks. Four subjects (20 percent) were given an additional intravitreal Avastin injection at week 18. Gains or loss of lines on Snellen acuity was used as the primary endpoint.

-- The study showed that patients achieved clinically meaningful responses as determined by visual acuity, dilated funduscopy, fundus fluorescein angiography (FFA) and optical coherence tomography (OCT).

-- After 24 weeks, 7/20 (35 percent) patients gained three lines or more of vision and 20/20 (100 percent) had stabilized vision or gained at least one line of vision. Significant improvements were also made in macular edema as measured by OCT.

These promising preliminary results suggest that further studiesare needed to investigate this treatment approach which may takeadvantage of the long-term safety profile of Macugen while anon-selective anti-VEGF therapy is used initially or as a booster foradded clinical benefit.

OSI and Pfizer are planning to initiate a Phase IV trial that willfurther examine the efficacy of Macugen in patients with neovascularAMD who have previously been treated with different therapies thathave resulted in a clinically significant and measurable reduction ofmacular edema. The trial is scheduled to begin in the second half of2006 and intends to enroll up to 1,000 patients at 100 sites.

Macugen as Primary Therapy in Neovascular AMD Patients with EarlyLesions

Macugen as Primary Therapy for AMD Lesions of All AngiographicSubtypes, presented by Polly Quiram, MD, and colleagues at AssociatedRetinal Consultants, Beaumont Hospital, MI. A retrospective review ofpatient data in 90 newly diagnosed neovascular AMD patients undergoingtreatment with Macugen as primary therapy showed:

-- Ninety percent (81/90) of patients had stabilization or improved vision: 20 percent (18/90) gained => 3 lines of Snellen visual acuity and 70 percent (63/90) had stabilized vision (defined as no change +/- 2 lines).

-- Only 10 percent (9/90) of patients reported loss of => 3 lines of vision.

-- This study suggests that Macugen is effective as primary treatment for new neovascular AMD lesions of any angiographic subtype.

Increased Risk of Co-morbid Conditions in Wet AMD Patients

Comparison of Co-morbid Conditions Between Wet AMD Patients and aControl Cohort in the Medicare Population, presented by Sonali Shah,RPh, MBA, MPH, Pfizer Inc. A retrospective analysis of 35,000 Medicarepatient reimbursement claims from 2003 found that as compared to thecontrol group, neovascular AMD patients had:

-- 31.5 percent higher risk of hypertension

-- 9.8 percent higher risk of diabetes

-- 36.4 percent higher risk of lipid disorders

-- 11.6 percent higher risk of stroke

-- 22.3 percent higher risk of gastro-intestinal disorders

-- 11.4 percent higher risk of depression

Association Between Neovascular Age-Related Macular Degenerationand Incidence of Myocardial Infarction (MI), presented by IngridScott, MD, MPH, Penn State College of Medicine. A retrospective reviewof Medicare reimbursement claims from 2000 to 2003 found thatneovascular AMD is associated with a higher risk of myocardialinfarction, or heart attack, independent of demographic factors andother co-morbid conditions.

These data suggest that safety is an important consideration whentreating neovascular AMD since patients are typically over the age of65 and are already at risk for cardiovascular and thromboembolicdiseases.

Macugen Study in Diabetic Retinopathy Patients

Use of Pegaptanib Sodium (Macugen) for Regression of ProliferativeDiabetic Retinopathy, presented by Victor Gonzalez, MD, Valley RetinaInstitute, TX. Ten patients with proliferative diabetic retinopathywere administered an intravitreal injection of 0.3 mg Macugen everysix weeks. Results showed that:

-- All 10 eyes injected with Macugen had a marked regression of neovascularization within the first three weeks of treatment.

-- In addition, there was a decrease in central retinal thickness, also within the first three weeks, without significant adverse events.

These preliminary findings suggest that selective VEGF blockadewith Macugen may reduce the progression of proliferative diabeticretinopathy and provide beneficial effects in preventing severe visionloss due to proliferative diabetic retinopathy, but further studieswill be needed to confirm and evaluate these effects. The preliminarydata also suggest that selective VEGF blockade may allow for lesslaser therapy, a destructive intervention that can lead toirreversible side-effects, in treating diabetic retinopathy.

About Macugen

Macugen is indicated in the United States for the treatment ofneovascular AMD and is administered in a 0.3-mg dose once every sixweeks by intravitreal injection. Macugen is a pegylated anti-VEGFaptamer, which binds to vascular endothelial growth factor (VEGF).VEGF is a protein that plays a critical role in angiogenesis (theformation of new blood vessels) and increased permeability (leakagefrom blood vessels), two pathological processes that contribute to thevision loss associated with neovascular AMD.

Macugen has been approved by regulatory authorities in the UnitedStates, European Union, Canada, Brazil, Argentina, Peru, Pakistan, thePhilippines, and Switzerland, with filings submitted in 14 othercountries. OSI and Pfizer co-promote Macugen in the United States. OSIhas granted Pfizer exclusive rights to commercialize Macugen incountries outside the United States pursuant to a royalty-bearinglicensing agreement.

For full prescribing information about Macugen, please visithttp://www.macugen.com.

Important Safety Information

Macugen is contraindicated in patients with ocular or periocularinfections or with known hypersensitivity to pegaptanib sodium or anyother excipient in this product.

Safety and efficacy of Macugen have been demonstrated incontrolled clinical studies for up to 2 years.

Intravitreal injections including those with Macugen have beenassociated with endophthalmitis. Proper aseptic injection technique --which includes use of sterile gloves, a sterile drape, and a sterileeyelid speculum (or equivalent) -- should always be utilized whenadministering Macugen. In addition, patients should be monitoredduring the week following the injection to permit early treatment,should an infection occur.

Increases in intraocular pressure (IOP) have been seen within 30minutes of injection with Macugen. Therefore, IOP as well as theperfusion of the optic nerve head should be monitored and managedappropriately.

Serious adverse events related to the injection procedureoccurring in <1% of intravitreal injections included endophthalmitis,retinal detachment, and iatrogenic traumatic cataract.

Most frequently reported adverse events in patients treated for upto two years were anterior chamber inflammation, blurred vision,cataract, conjunctival hemorrhage, corneal edema, eye discharge, eyeirritation, eye pain, hypertension, increased IOP, ocular discomfort,punctate keratitis, reduced visual acuity, visual disturbance,vitreous floaters, and vitreous opacities. These events occurred inapproximately 10% to 40% of patients.

Rare cases of anaphylaxis/anaphylactoid reactions, includingangioedema, have been reported in postmarketing experience followingthe intravitreal administration procedure.

The patient's medical history for hypersensitivity reactionsshould be evaluated prior to performing the intravitreal procedure.

About OSI Pharmaceuticals

OSI Pharmaceuticals is committed to "shaping medicines andchanging lives" by discovering, developing and commercializinghigh-quality and novel pharmaceutical products that extend life orimprove the quality of life for patients with cancer, eye diseases,and diabetes. The Company operates through three business teams, (OSI)Oncology, (OSI) Eyetech and (OSI) Prosidion. (OSI) Oncology is focusedon developing molecular targeted therapies designed to change theparadigm of cancer care. (OSI) Eyetech specializes in the developmentand commercialization of novel therapeutics to treat diseases of theeye. (OSI) Prosidion is committed to the generation of novel, targetedtherapies for the treatment of type 2 diabetes and obesity. OSI'sflagship product, Tarceva(R) (erlotinib), is the first drug discoveredand developed by OSI to obtain FDA approval and the only EGFRinhibitor to have demonstrated the ability to improve survival in bothnon-small cell lung cancer and pancreatic cancer patients. OSI marketsTarceva through partnerships with Genentech, Inc. in the United Statesand with Roche throughout the rest of the world. Macugen(R)(pegaptanib sodium injection) is approved in the United States for thetreatment of neovascular age-related macular degeneration. OSIcommercializes Macugen in partnership with Pfizer Inc. For additionalinformation about OSI, please visit http://www.osip.com.

This news release contains forward-looking statements. Thesestatements are subject to known and unknown risks and uncertaintiesthat may cause actual future experience and results to differmaterially from the statements made. Factors that might cause such adifference include, among others, the completion of clinical trials,the FDA review process and other governmental regulation, OSI's andits collaborators' abilities to successfully develop and commercializedrug candidates, competition from other pharmaceutical companies, theability to effectively market products, and other factors described inOSI Pharmaceuticals' filings with the Securities and ExchangeCommission.