8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

Current Report Pursuant to Section 13 or 15(d) of
The Securities Exchange Act of 1934

June 10, 2008

Date of Report (Date of earliest event reported)

OSI PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Delaware	0-15190	13-3159796
(State or other jurisdiction of	(Commission	(I.R.S. Employer
incorporation)	File Number)	Identification No.)

41 Pinelawn Road
Melville, NY 11747

(Address of principal executive offices)

(631) 962-2000

(Registrant’s telephone number, including area code)

N/A

(Former name or former address,

if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a- 12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01. Other Events.

     On June 10, 2008, OSI Pharmaceuticals, Inc. (“OSI”) announced that it had provided an informational update on data from its two preclinical development compounds, PSN821, a novel, orally available agonist of the G-protein coupled receptor, GPR119, being developed for the treatment of type 2 diabetes and obesity, and PSN602, an oral dual serotonin and norepinephrine reuptake inhibitor and 5-HT1A agonist being developed for the treatment of obesity, at the annual meeting of the American Diabetes Association in San Francisco, California. A copy of the press release, dated June 10, 2008, is attached hereto as Exhibit 99.1.

     On June 19, 2008, OSI announced that it had initiated the first-in-human clinical study for PSN602. A copy of the press release, dated June 19, 2008, is attached hereto as Exhibit 99.2.

Item 9.01. Financial Statements and Exhibits.

Exhibit No.	Description
99.1	Press Release dated June 10, 2008.
99.2	Press Release dated June 19, 2008.

SIGNATURE

     Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: June 20, 2008	OSI PHARMACEUTICALS, INC.
	By:	/s/ Barbara A. Wood Barbara A. Wood
		Senior Vice President, General Counsel and Secretary

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EXHIBIT INDEX

Exhibit No.	Description
99.1	Press Release dated June 10, 2008.
99.2	Press Release dated June 19, 2008.

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EX-99.1

Exhibit 99.1

NEWS RELEASE

Contact:
	OSI Pharmaceuticals, Inc.	Burns McClellan (Representing OSI)
	Kathy Galante (Investors/Media)	Justin Jackson/Kathy Nugent (Media)
	631-962-2043	212-213-0006
	Kim Wittig (Media)
	631-962-2135

OSI PHARMACEUTICALS PRESENTS DIABETES/OBESITY PRECLINICAL
COMPOUNDS, PSN821 AND PSN602, AT ANNUAL MEETING OF THE
AMERICAN DIABETES ASSOCIATION

MELVILLE, NY — June 10, 2008 — OSI Pharmaceuticals, Inc. (Nasdaq: OSIP) provided an informational update on data from its two preclinical development compounds, PSN821 and PSN602. This information was presented at the annual meeting of the American Diabetes Association in San Francisco, CA. Preclinical data on PSN821, a novel, orally available agonist of the G-protein coupled receptor GPR119, being developed for the treatment of type 2 diabetes and obesity, were presented in an oral presentation. Also presented were preclinical data on PSN602, an oral dual serotonin and norepinephrine reuptake inhibitor and 5-HT_1A agonist, being developed for the treatment of obesity. Both compounds are due to enter Phase I clinical trials in 2008.

“With diabetes and obesity rapidly emerging as a global health care problem that threatens to reach pandemic levels we recognize the need for novel, next-generation drugs and are encouraged by our research from both of these programs,” said Anker Lundemose, M.D., Ph.D., President of (OSI) Prosidion. “PSN821 has the potential to be the first orally available molecule which delivers both glucose control and substantial weight loss, while PSN602 is designed to give greater weight loss efficacy without causing the cardiovascular side effects seen with some anti-obesity agents.”

Following are summaries of the two presentations:

PSN821: A Novel Oral GPR119 Agonist for the Treatment of Type 2 Diabetes Producing Substantial Glucose Lowering and Weight Loss in Rats (Matthew Fyfe et al., Abstract # 297-OR)

In this presentation, OSI researchers presented preclinical data suggesting that PSN821 has the potential to achieve, as an oral agent, both substantial glucose lowering and meaningful

body weight loss in patients with type 2 diabetes. PSN821, which stimulated the release of both insulin and Glucagon-like peptide-1 (GLP-1), demonstrated pronounced glucose lowering in rodent models of type 2 diabetes with no loss of efficacy on repeated administration, and substantial reductions of body weight in a rodent model of obesity.

Data from the studies showed, in male diabetic ZDF rats, that both acute and chronic administration of PSN821, given orally, significantly and dose-dependently reduced glucose excursions in an oral glucose tolerance test. Further, in prediabetic male ZDF rats daily oral dosing of PSN821 for 8 weeks significantly lowered non-fasting blood glucose concentrations and HbA_1c levels compared to vehicle. Data also showed that in weight-stable, dietary-induced obese (DIO) female Wistar rats, daily oral dosing of PSN821 for 4 weeks reduced body weight substantially and significantly by 8.8%, comparing favorably with the 10.6% weight loss induced by a high dose of the prescribed anti-obesity agent, sibutramine.

PSN602: A Novel Monoamine Reuptake Inhibitor with 5-HT_1A Agonism That, in Rats, Exhibits Equivalent Weight Loss to Sibutramine with a Superior Cardiovascular Profile (Gerard H Thomas et al., Abstract # 1744-P)

Sibutramine is a dual serotonin (5-HT) / norepinephrine (NE) reuptake inhibitor approved for the treatment of obesity. It is associated with elevations in blood pressure and heart rate in some patients, raising safety concerns and limiting the ability to dose titrate upwards to achieve greater efficacy. It was hypothesized that the addition of 5-HT_1A agonism to monoamine reuptake inhibition would reduce the risk of unwanted cardiovascular activity. OSI researchers presented preclinical data demonstrating that PSN602 was as effective as a high dose of sibutramine at reducing body weight in a rodent model of obesity, but exhibited a more favorable cardiovascular profile after single doses.

Data from the study showed that PSN602, in vitro, is a potent inhibitor of both NE and 5-HT reuptake and a full agonist at the 5-HT_1A receptor. In weight-stable, dietary-induced obese (DIO) female Wistar rats, daily oral dosing of PSN602 for 4 weeks significantly reduced body weight by 9-17% compared with controls, matching the weight loss (14%) induced by a high dose of sibutramine. In telemetered rats, single oral doses of PSN602 (up to 3 ´ ED₅₀ to inhibit food intake over 24h), in contrast to sibutramine (2 ´ ED₅₀ to inhibit food intake over 24h), caused no significant rise in mean 2-8h blood pressure or mean 2-8h heart rate. Translation of these effects to man would potentially allow dose-escalation of PSN602 to achieve greater weight loss than that seen with sibutramine.

About OSI Pharmaceuticals
OSI Pharmaceuticals is committed to “shaping medicine and changing lives” by discovering, developing and commercializing high-quality and novel pharmaceutical products designed to extend life and/or improve the quality of life for patients with cancer and diabetes/obesity. The Company’s oncology programs are focused on developing molecular targeted therapies designed to change the paradigm of cancer care. OSI’s diabetes/obesity efforts are committed to the generation of novel, targeted therapies for the treatment of type 2 diabetes and obesity. OSI’s flagship product, Tarceva^® (erlotinib), is the first drug discovered and developed by OSI to obtain FDA approval and the only EGFR inhibitor to have demonstrated the ability to improve survival in both non-small cell lung cancer and pancreatic cancer patients in certain settings. OSI markets Tarceva through partnerships with Genentech, Inc. in the United States

and with Roche throughout the rest of the world. For additional information about OSI, please visit <http://www.osip.com>.

This news release contains forward-looking statements. These statements are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. Factors that might cause such a difference include, among others, the completion of clinical trials, the FDA review process and other governmental regulation, OSI’s and its collaborators’ abilities to successfully develop and commercialize drug candidates, competition from other pharmaceutical companies, the ability to effectively market products, and other factors described in OSI Pharmaceuticals’ filings with the Securities and Exchange Commission.

EX-99.2

Exhibit 99.2

NEWS RELEASE

Contact:
	OSI Pharmaceuticals, Inc.	Burns McClellan (Representing OSI)
	Kathy Galante (Investors/Media)	Justin Jackson/Kathy Nugent (Media)
	631-962-2043	212-213-0006
	Kim Wittig (Media)
	631-962-2135

OSI PHARMACEUTICALS INITIATES CLINICAL
DEVELOPMENT PROGRAM FOR ANTI-OBESITY
CANDIDATE, PSN602

MELVILLE, NEW YORK- June 19, 2008 — OSI Pharmaceuticals, Inc. (Nasdaq: OSIP) announced today that it has initiated the first-in-human clinical study of its development compound PSN602. Discovered by OSI’s diabetes and obesity team, PSN602 is an oral dual serotonin and norepinephrine reuptake inhibitor and 5-HT_1A agonist, being developed for the treatment of obesity. PSN602 is the first clinical candidate to emerge from the Company’s research efforts in obesity.

“Our research efforts are focused on designing innovative, next-generation, small molecule compounds to provide safer or more effective options for the treatment of type 2 diabetes and obesity,” stated Anker Lundemose, M.D., Ph.D., President of (OSI) Prosidion. “We believe that not only does PSN602 have the potential to have a favourable side-effect profile relative to current therapies for obesity, but also the potential to provide greater efficacy.”

The double-blind, placebo-controlled, ascending, single and multiple, oral dose study is designed to provide preliminary information on the safety, tolerability and pharmacokinetics of PSN602 in healthy lean and overweight/obese subjects, as well as on the effects of PSN602 on appetite and food intake in healthy overweight/obese subjects.

Background

OSI’s research showed, in preclinical in vivo models, that PSN602 was at least as effective at reducing body weight as a high dose of the anti-obesity agent sibutramine, with a more favourable cardiovascular profile, supporting the hypothesis that the 5-HT_1A agonism component of PSN602 could potentially counterbalance the undesirable cardiovascular activity seen with sibutramine.

About Obesity

Obesity is a state of excess body fat. The World Health Organization expresses the prevalence of obesity by using body mass index (BMI), a simple index of weight-for-height that classifies underweight, overweight and obesity in adults. Obesity has

reached epidemic proportions globally with more than 1 billion adults overweight, of which at least 300 million are clinically obese. Excess weight and obesity lead to adverse metabolic effects on blood pressure, lipid levels and insulin resistance and thus pose a major risk for serious chronic diseases, including hypertension, type 2 diabetes and cardiovascular disease. In addition, obesity increases the risk of respiratory difficulties, chronic musculoskeletal problems, infertility, gall bladder disease and certain forms of cancer.

About OSI Pharmaceuticals

OSI Pharmaceuticals is committed to “shaping medicine and changing lives” by discovering, developing and commercializing high-quality and novel pharmaceutical products designed to extend life and/or improve the quality of life for patients with cancer and diabetes/obesity. The Company’s oncology programs are focused on developing molecular targeted therapies designed to change the paradigm of cancer care. OSI’s diabetes/obesity efforts are committed to the generation of novel, targeted therapies for the treatment of type 2 diabetes and obesity. OSI’s flagship product, Tarceva^® (erlotinib), is the first drug discovered and developed by OSI to obtain FDA approval and the only EGFR inhibitor to have demonstrated the ability to improve survival in both non-small cell lung cancer and pancreatic cancer patients in certain settings. OSI markets Tarceva through partnerships with Genentech, Inc. in the United States and with Roche throughout the rest of the world. For additional information about OSI, please visit <http://www.osip.com>.

This news release contains forward-looking statements. These statements are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. Factors that might cause such a difference include, among others, the completion of clinical trials, the FDA review process and other governmental regulation, OSI’s and its collaborators’ abilities to successfully develop and commercialize drug candidates, competition from other pharmaceutical companies, the ability to effectively market products, and other factors described in OSI Pharmaceuticals’ filings with the Securities and Exchange Commission.