UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ¨                            Filed by a Party other than the Registrant  x

Check the appropriate box:

¨ Preliminary Proxy Statement

¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨ Definitive Proxy Statement

¨ Definitive Additional Materials

x Soliciting Material Pursuant to §240.14a-12

OSI Pharmaceuticals, Inc.

(Name of Registrant as Specified In Its Charter)

Astellas Pharma Inc., Astellas US Holding, Inc., Ruby Acquisition, Inc.

(Names of Persons Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x No fee required.

¨ Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

1) Title of each class of securities to which transaction applies:

2) Aggregate number of securities to which transaction applies:

3) Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

4) Proposed maximum aggregate value of transaction:

5) Total fee paid:

¨ Fee paid previously with preliminary materials.

¨ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the form or schedule and the date of its filing:

1) Amount Previously Paid:

2) Form, Schedule or Registration Statement No:

3) Filing Party:

4) Date Filed:

On April 1, 2010, Astellas Pharma Inc. posted the following investor presentation on its website, www.oncologyleader.com:

Astellas Offer to Acquire OSI

Investor Presentation

Investor Presentation

April 2010

April 2010

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2

Executive Summary

•

•

OSI’s share price has lagged that of its peers and its performance has

OSI’s share price has lagged that of its peers and its performance has

fallen short of Wall Street expectations

fallen short of Wall Street expectations

•

•

Astellas’

Astellas’

$52 per share offer reflects the potential for both Tarceva and

$52 per share offer reflects the potential for both Tarceva and

OSI’s pipeline products as well as the value of OSI's financial assets

OSI’s pipeline products as well as the value of OSI's financial assets

•

•

This offer represents a significant premium relative to comparable

This offer represents a significant premium relative to comparable

companies and relative to the value OSI is expected to achieve on its

companies and relative to the value OSI is expected to achieve on its

own, according to Wall Street estimates

own, according to Wall Street estimates

•

•

As evidenced by the CV Therapeutics process, Astellas is a disciplined

As evidenced by the CV Therapeutics process, Astellas is a disciplined

buyer that will not pay beyond its opinion of intrinsic value simply to win

buyer that will not pay beyond its opinion of intrinsic value simply to win

an asset

an asset

•

•

Astellas has recently signed a confidentiality agreement with OSI,

Astellas has recently signed a confidentiality agreement with OSI,

providing it access to confidential information, which may lead it to

providing it access to confidential information, which may lead it to

confirm, raise or lower its offer price

confirm, raise or lower its offer price

3

OSI’s Share Price Has Lagged Its Peers

•

Prior to the announcement of Astellas’

tender

offer on March 1, 2010, OSI’s

share price had significantly underperformed its peers in the AMEX

Biotechnology (BTK) index over the last several years

Note:

February 26, 2010 was the last trading day prior

to

public

announcement

of

Astellas’

tender

offer.

4

OSI’s 2009 Financial Results Contribute to

Underperformance of Its Stock

•

•

OSI’s continued inability to exceed Wall Street estimates caused it to

OSI’s continued inability to exceed Wall Street estimates caused it to

significantly underperform its peers in 2009

significantly underperform its peers in 2009

Wall Street EPS Consensus Estimates vs. Actual Results

Share Price Performance

(January 1, 2009 –

December 31, 2009)

$0.31

$0.33

$0.32

$0.42

$0.28

$0.28

$0.30

$0.42

0.00

0.10

0.20

0.30

0.40

0.50

1Q CY09

2Q CY09

3Q CY09

4Q CY09

Wall Street Mean Consensus

OSI Actuals

(20%)

+46%

-10%

-15%

-6%

0%

(1) Denotes Wall Street mean consensus estimates for

diluted EPS from continuing operations.

(1)

5

Astellas’

Current Offer Represents Full and Fair

Value for OSI

•

•

Based on information available to Astellas, $52 in cash per share

Based on information available to Astellas, $52 in cash per share

represents a full and fair value for OSI

represents a full and fair value for OSI

•

•

This represents both the value created by OSI to date as well as

This represents both the value created by OSI to date as well as

its future prospects

its future prospects

•

•

The offer stands in comparison to Wall Street research analysts

The offer stands in comparison to Wall Street research analysts

that had an average 12-month price target of only $40 prior to

that had an average 12-month price target of only $40 prior to

announcement of Astellas' offer

announcement of Astellas' offer

•

•

Astellas reduced the $55-57 per share offer it made in 2009 to

Astellas reduced the $55-57 per share offer it made in 2009 to

correspond with Astellas’

correspond with Astellas’

current, updated view of the value of all

current, updated view of the value of all

of OSI’s future prospects, including the remaining useful life of

of OSI’s future prospects, including the remaining useful life of

the Tarceva patents

the Tarceva patents

6

Wall Street Commentary on Tarceva Maintenance

•

•

Astellas' offer attributes value to all of the potential label expansions for

Astellas' offer attributes value to all of the potential label expansions for

Tarceva, including maintenance approval. Wall Street research analysts

Tarceva, including maintenance approval. Wall Street research analysts

generally do not see significant value associated with maintenance

generally do not see significant value associated with maintenance

approval

approval

"The EU approval of Tarceva as first-line maintenance therapy (FLMT) is a positive surprise given the

negative FDA ODAC

panel...The commercial hurdle would likely be high for Tarceva, if approved....We estimate the sales potential of

FLMT in the EU to be about $100-150 mm, representing about $1-$2 per share in NPV.”

Goldman Sachs –

March 19, 2010

"While today's news is an incremental positive, we see maintenance as a niche opportunity

with peak potential of

$50M to $100M in Europe...we estimate this could be worth an incremental $1.00/share to base business....We don't think

this announcement supports a materially higher bid from current levels.”

JP Morgan –

March 19, 2010

“OSIP's

confidence in its valuation is based on its discussions with FDA for the maintenance indication and ongoing clinical

trials. We already have a high level of confidence that the FDA will approve Tarceva in the maintenance setting but believe

there is likely only modest impact to sales

as a result.”

RBC –

March 15, 2010

“We do remain skeptical on the maintenance setting, however,

and believe that even under a best-case scenario, the

FDA...gives Tarceva a restricted label that contraindicates use in the squamous

cell and EGFR mutant populations –

at which

point, any competitive differentiation relative to Alimta, which has better data in non-squamous

patients,

becomes difficult.”

Thomas Weisel

–

February 24, 2010

Source: Wall Street research.

Note:

Permission to use quotations was neither sought

nor obtained.

7

Comparable P/E and PEG multiples

•

•

On a growth-adjusted basis, Astellas’

On a growth-adjusted basis, Astellas’

$52.00 per share offer is a

$52.00 per share offer is a

significant premium to other established pharmaceutical firms and firms

significant premium to other established pharmaceutical firms and firms

with higher growth expectations

with higher growth expectations

2010E P/E

LTG

33.6x

13.5%

12.4x

8.4%

19.5x

18.9%

10.9x

12.4%

12.6x

15.4%

16.7x

10.1%

20.7x

13.7%

33.2%

48.0x

24.1x

23.4%

11.6x

11.8%

13.6x

16.2%

23.9x

13.5%

11.7%

13.3x

2.5x

1.8x

1.7x

1.5x

1.5x

1.4x

1.1x

1.0x

1.0x

1.0x

0.9x

0.8x

0.8x

0.0

0.5

1.0

1.5

2.0

2.5

3.0x

OSI: At

$52 /

share

OSI:

Before

Offer

Shire

Allergan

Biogen

Idec

Alexion

King

Genzyme

Celgene

Actelion

Cephalon

Cubist

Gilead

Source: Wall Street mean consensus research estimates.

Note:

Market data as of March 30, 2010.

8

In Today’s Dollars, OSI Won’t Reach $52 Until After 2013

•

Even if OSI’s shareholders believe the Company will successfully execute on its

strategy for the next three and a half years, and achieve Wall Street’s earnings

estimates, on a present value basis they still will not achieve the same value they

could receive from Astellas today

Forward EPS

Multiple

$1.55

23.9x

23.9x

23.9x

23.9x

$1.84

$1.96

$2.11

(1)

(2)

23.9x

$2.26

23.9x

$2.43

23.9x

$2.59

23.9x

$2.71

23.9x

$2.84

Note:

Prices calculated using an 8% discount rate.

(1)

Based on a rolling forward four quarter estimate of OSI’s

EPS, according to Wall Street mean consensus estimates.

(2)

OSI’s forward P/E multiple based on a closing price of

$37.02 and 2010 estimated EPS of $1.55 according to Wall

Street research, as of February 26, 2010.

$37.02

$50.80

$50.51

$50.13

$48.78

$47.25

$45.84

$44.26

$43.04

35.00

40.00

45.00

50.00

$55.00

2/26/10

6/30/10

12/31/10

6/30/11

12/31/11

6/30/12

12/31/12

6/30/13

12/31/13

Astellas’

Offer Price: $52.00

9

Biogen

Idec’s Share Price History During Icahn’s Offer

•

•

Biogen’s

Biogen’s

failed efforts to find a potential buyer resulted in share prices

failed efforts to find a potential buyer resulted in share prices

lower than pre-announcement levels

lower than pre-announcement levels

October 1, 2007 –

March 1, 2008

Biogen Idec

10/13/07:

Biogen

announces it has

commenced exploring

alternatives after receiving

an offer of $23bn from

Icahn

12/12/07:

Biogen ends

its strategic review after

the process failed to yield

any definitive offers

-24%

-$5bn of

market cap

Market Cap: $17 bn

Market Cap: $22 bn

1/28/08:

Icahn sends

a notice to Biogen

seeking to nominate

three members to the

Board of Directors

Oct 07

Nov 07

Dec 07

Jan 08

Feb 08

50

60

70

80

90

10

Outcome of Buyer Discussions Can Be

Completed Quickly

•

•

OSI’s Board of Directors instructed OSI’s management and

OSI’s Board of Directors instructed OSI’s management and

financial advisors to contact other parties to explore a transaction

financial advisors to contact other parties to explore a transaction

•

•

The sales process should not be used as a delay tactic

The sales process should not be used as a delay tactic

OSI has ample time to locate a bid greater than $52 that has the

same certainty of value and completion as Astellas’

offer

Considering (a) OSI has a straightforward business and assets and

(b) the sophistication of the buyer universe, OSI should be able

to

complete the process expeditiously

11

Conclusion

•

•

If OSI does not announce a deal soon, shareholders will have to

If OSI does not announce a deal soon, shareholders will have to

choose:

choose:

Stay the course with OSI

Realize immediate value from Astellas’

offer

•

•

If

If

they

they

elect

elect

to

to

stay

stay

the

the

course

course

with

with

OSI,

OSI,

shareholders

shareholders

may

may

face

face

a

a

rapid decline in OSI’s share price to pre-offer levels and Tarceva’s

rapid decline in OSI’s share price to pre-offer levels and Tarceva’s

useful life will have continued to diminish

useful life will have continued to diminish

•

•

As

As

evidenced

evidenced

by

by

the

the

CV

CV

Therapeutics

Therapeutics

process

process

in

in

2009,

2009,

Astellas

Astellas

is

is

a

a

disciplined buyer that understands intrinsic value, and it will not

disciplined buyer that understands intrinsic value, and it will not

pay beyond that value simply to win an asset

pay beyond that value simply to win an asset

Additional Information

Further details related to this announcement can be found on www.oncologyleader.com

Media Contacts

Brunswick New York

+1 212 333 3810

Stan Neve

Sarah Lubman

Brunswick Hong Kong

+852 9850 5033

Joseph Lo

Information Agent

Georgeson

+ 1 212 440 9872

Thomas Gardiner

About Astellas

Astellas

Pharma

Inc.,

located

in

Tokyo,

Japan,

is

a

pharmaceutical

company

dedicated

to

improving

the

health

of

people

around

the

world

through

the

provision

of

innovative

and

reliable

pharmaceuticals.

Astellas

has

approximately

14,200

employees

worldwide.

The

organization

is

committed

to

becoming

a

global

category

leader

in

urology,

immunology

&

infectious

diseases,

neuroscience,

DM

complications

&

metabolic

diseases

and

oncology.

For

more

information

on

Astellas

Pharma

Inc.,

please

visit

our

website

at

http://www.astellas.com/en.

Important Additional Information

This

communication

is

for

informational

purposes

only

and

does

not

constitute

an

offer

to

purchase

or

a

solicitation

of

an

offer

to

sell

OSI

Pharmaceuticals

(“OSI”)

common

stock.

The

tender

offer

(the

“Tender

Offer”)

is

being

made

pursuant

to

a

tender

offer

statement

on

Schedule

TO

(including

the

Offer

to

Purchase,

Letter

of

Transmittal

and

other

related

tender

offer

materials)

filed

by

Astellas

Pharma

Inc.,

Astellas

US

Holding,

Inc.

and

Ruby

Acquisition,

Inc.

(collectively,

“Astellas”)

with

the

Securities

and

Exchange

Commission

(“SEC”).

These

materials,

as

they

may

be

amended

from

time

to

time,

contain

important

information,

including

the

terms

and

conditions

of

the

Tender

Offer,

that

should

be

read

carefully

before

any

decision

is

made

with

respect

to

the

Tender

Offer.

Investors

and

security

holders

may

obtain

a

free

copy

of

these

materials

and

other

documents

filed

by

Astellas

with

the

SEC

at

the

website

maintained

by

the

SEC

at

www.sec.gov.

The

Offer

to

Purchase,

Letter

of

Transmittal

and

other

related

Tender

Offer

materials

may

also

be

obtained

for

free

by

contacting

the

information

agent

for

the

Tender

Offer,

Georgeson

Inc.,

at

(212)

440-9800

for

banks

and

brokers

and

at

(800)

213-0473

for

persons

other

than

banks

and

brokers.

In

connection

with

Astellas’

proposal

to

nominate

directors

at

OSI’s

annual

meeting

of

stockholders,

Astellas

expects

to

file

a

proxy

statement

with

the

SEC.

Investors

and

security

holders

of

OSI

are

urged

to

read

the

proxy

statement

and

other

documents

related

to

the

solicitation

of

proxies

filed

with

the

SEC

carefully

in

their

entirety

when

they

become

available

because

they

will

contain

important

information.

Stockholders

of

OSI

and

other

interested

parties

may

obtain,

free

of

charge,

copies

of

the

proxy

statement

(when

available),

and

any

other

documents

filed

by

Astellas

with

the

SEC

in

connection

with

the

proxy

solicitation,

at

the

SEC's

website

as

described

above.

The

proxy

statement

(when

available)

and

these

other

documents

may

also

be

obtained

free

of

charge

by

contacting

Georgeson

Inc.

at

the

numbers

listed

above.

Astellas

and

certain

of

their

directors

and

executive

officers

and

the

individuals

to

be

nominated

by

Astellas

for

election

to

OSI’s

board

of

directors

may

be

deemed

to

be

participants

in

the

solicitation

of

proxies

in

connection

with

the

proposed

transaction.

Information

regarding

these

directors

and

executive

officers

and

other

individuals

is

available

in

the

Schedule

TO

that

was

filed

March

2,

2010,

and

other

documents

filed

by

Astellas

with

the

SEC

as

described

above.

Further

information

will

be

available

in

any

proxy

statement

or

other

relevant

materials

filed

with

the

SEC

in

connection

with

the

solicitation

of

proxies

when

they

become

available.

No

assurance

can

be

given

that

the

proposed

transaction

described

herein

will

be

consummated

by

Astellas,

or

completed

on

the

terms

proposed

or

any

particular

schedule,

that

the

proposed

transaction

will

not

incur

delays

in

obtaining

the

regulatory,

board

or

stockholder

approvals

required

for

such

transaction,

or

that

Astellas

will

realize

the

anticipated

benefits

of

the

proposed

transaction.

Statement on Cautionary Factors

Any

statements

made

in

this

communication

that

are

not

statements

of

historical

fact,

including

statements

about

Astellas’

beliefs

and

expectations

and

statements

about

Astellas’

proposed

acquisition

of

OSI,

are

forward-looking

statements

and

should

be

evaluated

as

such.

Forward-looking

statements

include

statements

that

may

relate

to

Astellas’

plans,

objectives,

strategies,

goals,

future

events,

future

revenues

or

performance,

and

other

information

that

is

not

historical

information.

Factors

that

may

materially

affect

such

forward-looking

statements

include:

Astellas’

ability

to

successfully

complete

the

tender

offer

for

OSI’s

shares

or

realize

the

anticipated

benefits

of

the

transaction;

delays

in

obtaining

any

approvals

required

for

the

transaction,

or

an

inability

to

obtain

them

on

the

terms

proposed

or

on

the

anticipated

schedule;

and

the

failure

of

any

of

the

conditions

to

Astellas’

tender

offer

to

be

satisfied.

Any

information

regarding

OSI

contained

herein

has

been

taken

from,

or

is

based

upon,

publicly

available

information.

Although

Astellas

does

not

have

any

information

that

would

indicate

that

any

information

contained

herein

is

inaccurate

or

incomplete,

Astellas

has

not

had

the

opportunity

to

verify

any

such

information

and

does

not

undertake

any

responsibility

for

the

accuracy

or

completeness

of

such

information.

Astellas

does

not

undertake,

and

specifically

disclaims,

any

obligation

or

responsibility

to

update

or

amend

any

of

the

information

above

except

as

otherwise

required

by

law.

*****

*****