SC TO-I/A

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)
Of the Securities Exchange Act of 1934
(Amendment No. 2)

OSI PHARMACEUTICALS, INC.

(Name of Subject Company (Issuer) and Filing Person (Offeror))

2% Convertible Senior Subordinated Notes due 2025
3% Convertible Senior Subordinated Notes due 2038
(Titles of Class of Securities)

671040 AF0
671040 AE3
671040 AG8
671040 AH6
(CUSIP Number of Class of Securities)

Barbara A. Wood, Esq.
Senior Vice President, General Counsel and Secretary
420 Saw Mill River Road
Ardsley, NY 10502
(914) 231-8000
(Name, Address and Telephone Number of Person Authorized to Receive Notices and
Communications on Behalf of the Filing Persons)

With a copy to:

Craigh Leonard, Esq.
Morrison & Foerster LLP
1290 Avenue of the Americas
New York, New York 10104
(212) 468 8007

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$275,547,050	$19,647.00

*

Estimated for purposes of calculating the amount of the filing fee only, this amount is based on the purchase of $115 million aggregate principal amount of the 2% Convertible Senior Subordinated Notes due 2025 at the purchase price of $1,002.67 per $1,000 of Notes outstanding as of June 15, 2010 and $160 million aggregate principal amount of the 3% Convertible Senior Subordinated Notes due 2038 at the purchase price of $1,001.50 per $1,000 of Notes outstanding as of June 15, 2010.

**

Previously Paid.

o  Check the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid: N/A	Filing Party: N/A
Form or Registration No.: N/A	Date Filed: N/A

o  Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

o  third-party tender offer subject to Rule 14d-1.

þ  issuer tender offer subject to Rule 13e-4.

o  going-private transaction subject to Rule 13e-3.

o  amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer: o

TABLE OF CONTENTS

	Item 4. Terms of the Transaction.
	Item 12. Exhibits.
SIGNATURE
EXHIBIT INDEX
EX-99.A.1.C
EX-99.A.1.D
EX-99.A.5.C
EX-99.A.5.D

AMENDMENT NO. 2 to SCHEDULE TO

     This Amendment No. 2 (“Amendment No. 2”) amends and supplements the Tender Offer Statement on Schedule TO (as amended, the “Schedule TO”) originally filed with the Securities and Exchange Commission (the “SEC”) on June 17, 2010 by OSI Pharmaceuticals, Inc., a Delaware corporation (the “Company”), as amended by Amendment No. 1 (“Amendment No. 1”) to the Schedule TO filed with the SEC on June 18, 2010 by the Company, in connection with the Company’s Offer to Purchase for cash, on the terms and subject to the conditions set forth in the Offer to Purchase, dated June 17, 2010, relating to the 2% Convertible Senior Subordinated Notes due 2025 (the “2% Notes”), as supplemented and amended by the Supplement thereto dated June 29, 2010 (the “2% Notes Supplement”) and filed as Exhibit (a)(1)(C) hereto (as supplemented and amended, the “2% Notes Offer to Purchase”) and the Offer to Purchase, dated June 17, 2010, relating to the 3% Convertible Senior Subordinated Notes due 2038 (the “3% Notes”), as supplemented and amended by the Supplement thereto dated June 29, 2010 (the “3% Notes Supplement”) and filed as Exhibit (a)(1)(D) hereto (as supplemented and amended, the “3% Notes Offer to Purchase”), any and all of the Company’s outstanding 2% Notes and 3% Notes, each at a price of $1,000 per $1,000 in principal amount tendered, plus accrued and unpaid interest to, but excluding the purchase date.

     Except as set forth in this Amendment No. 2, the information set forth in the Schedule TO remains unchanged.

Item 4. Terms of the Transaction.

1. Item 4(a) of the Schedule TO is hereby supplemented and amended so that the information set forth in the 2% Notes Supplement and the 3% Notes Supplement is incorporated by reference.

Item 12. Exhibits.

1. Item 12 of the Schedule TO is hereby supplemented and amended in its entirety as follows:

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Exhibit No.	Description of Document
(a)(1)(A)*	2% Notes Offer to Purchase, dated June 17, 2010.
(a)(1)(B)*	3% Notes Offer to Purchase, dated June 17, 2010.
(a)(1)(C)**	Supplement to 2% Notes Offer to Purchase, dated June 29, 2010.
(a)(1)(D)**	Supplement to 3% Notes Offer to Purchase, dated June 29, 2010.
(a)(5)(A)*	2% Notes Fundamental Change Company Notice and Notice of Conversion, dated June 18, 2010.
(a)(5)(B)*	Press Release of the Company relating to Occurrence of a Fundamental Change for Convertible Notes, dated June 18, 2010.
(a)(5)(C)**	Amended and Restated Form of Fundamental Change Purchase Notice for 2% Notes.
(a)(5)(D)**	Amended and Restated Form of Fundamental Change Purchase Notice for 3% Notes.
(d)(1)	Indenture, dated December 21, 2005, by and between OSI Pharmaceuticals, Inc. and The Bank of New York Mellon (formerly known as The Bank of New York), filed by the Company as an exhibit to the Form 8-K filed on December 28, 2005 (file no. 000-15190), and incorporated herein by reference.
(d)(2)	Indenture, dated January 9, 2008, by and between OSI Pharmaceuticals, Inc. and The Bank of New York Mellon (formerly known as The Bank of New York), filed by the Company as an exhibit to the Form 8-K filed on January 15, 2008 (file no. 000-15190), and incorporated herein by reference.

*	Previously filed.
**	Filed herewith.

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SIGNATURE

     After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: June 29, 2010	OSI Pharmaceuticals, Inc.
	By:	/s/ Barbara A. Wood
		Name:	Barbara A. Wood
		Title:	Senior Vice President, General Counsel and Secretary

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EXHIBIT INDEX

Exhibit No.	Description of Document
(a)(1)(A)*	2% Notes Offer to Purchase, dated June 17, 2010.
(a)(1)(B)*	3% Notes Offer to Purchase, dated June 17, 2010.
(a)(1)(C)**	Supplement to 2% Notes Offer to Purchase, dated June 29, 2010.
(a)(1)(D)**	Supplement to 3% Notes Offer to Purchase, dated June 29, 2010.
(a)(5)(A)*	2% Notes Fundamental Change Company Notice and Notice of Conversion, dated June 18, 2010.
(a)(5)(B)*	Press Release of the Company relating to Occurrence of a Fundamental Change for Convertible Notes, dated June 18, 2010.
(a)(5)(C)**	Amended and Restated Form of Fundamental Change Purchase Notice for 2% Notes.
(a)(5)(D)**	Amended and Restated Form of Fundamental Change Purchase Notice for 3% Notes.
(d)(1)	Indenture, dated December 21, 2005, by and between OSI Pharmaceuticals, Inc. and The Bank of New York Mellon (formerly known as The Bank of New York), filed by the Company as an exhibit to the Form 8-K filed on December 28, 2005 (file no. 000-15190), and incorporated herein by reference.
(d)(2)	Indenture, dated January 9, 2008, by and between OSI Pharmaceuticals, Inc. and The Bank of New York Mellon (formerly known as The Bank of New York), filed by the Company as an exhibit to the Form 8-K filed on January 15, 2008 (file no. 000-15190), and incorporated herein by reference.

*	Previously filed.
**	Filed herewith.

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EX-99.A.1.C

Exhibit (a)(1)(C)

SUPPLEMENT NO. 1 TO OFFER TO PURCHASE

OSI PHARMACEUTICALS, INC.

Offer to Purchase for Cash
Any and All Outstanding
2% Convertible Senior Subordinated Notes due 2025
CUSIP No. 671040 AF0
CUSIP No. 671040 AE3

     This Supplement No. 1 to Offer to Purchase (this Supplement No. 1) supplements and amends the Offer to Purchase dated June 17, 2010 (the “Original Offer to Purchase”) relating to an offer by OSI Pharmaceuticals, Inc., a Delaware corporation (the “Company,” “we,” “us” and “our”), to purchase for cash, on the terms and subject to the conditions set forth in the Original Offer to Purchase (as supplemented and amended by this Supplement No. 1 and as it may be further supplemented and amended from time to time, the “Offer to Purchase”), any and all of its 2% Convertible Senior Subordinated Notes due 2025 (the “Notes”) at a purchase price of $1,000 per $1,000 principal amount of Notes plus accrued and unpaid interest to, but excluding, the applicable Purchase Date. You should carefully read the Original Offer to Purchase and this Supplement No. 1 to fully understand the terms of the Offer. Capitalized terms used and not otherwise defined in this Supplement No. 1 have the meanings given to them in the Original Offer to Purchase.

     This Supplement No. 1 supplements and amends information in the Original Offer to Purchase, and, accordingly, to the extent inconsistent, the information in this Supplement No. 1 supersedes the information contained in the Original Offer to Purchase. Any statement that is amended hereby shall not be deemed to constitute a part of the Offer to Purchase except as amended by this Supplement No. 1. Information contained in the Original Offer to Purchase and not addressed in this Supplement No. 1 remains unchanged.

     The Original Offer to Purchase is hereby supplemented and amended by inserting the following paragraph after the sixth full paragraph of Section 3.3 of the Original Offer to Purchase entitled “Conversion Rights of the Notes”:

     In accordance with the foregoing, if a Holder surrenders its Notes for conversion on or before July 9, 2010, the Holder will receive approximately $1,957.41 per $1,000 principal amount of Notes. If a Holder surrenders its Notes for conversion after July 9, 2010, the Holder will receive approximately $1,954.12 per $1,000 principal amount of Notes.

     You should review the Offer to Purchase carefully and consult with your own financial and tax advisors. You must make your own decision as to whether or not to tender your Notes for purchase and, if so, the amount of Notes to tender. None of the Company, the Acquirer, their

respective Boards of Directors, their respective employees, the Trustee, the Paying Agent or the Conversion Agent are making any representation or recommendation to any Holder as to whether or not to tender that Holder’s Notes.

The Paying Agent and the Conversion Agent is:
The Bank of New York Mellon,

By Hand or Overnight Delivery:	For Information:	By Facsimile:
The Bank of New York Mellon	Please call Sherma Thomas at	(212) 815-2742
Attention: Reorg Dept.	212-815-5283 if you have any
101 Barclay Street — 7E	questions	Attention:
New York, New York 10286		Dianne Amoroso

Additional copies of the Offer to Purchase may be obtained from the Paying Agent at its address set forth above.

Neither the Securities and Exchange Commission nor any state securities commission nor any other regulatory authority has approved or disapproved of these transactions or determined if this statement is truthful or complete. Any representation to the contrary is a criminal offense.

June 29, 2010

EX-99.A.1.D

Exhibit (a)(1)(D)

SUPPLEMENT NO. 1 TO OFFER TO PURCHASE

OSI PHARMACEUTICALS, INC.

Offer to Purchase for Cash
Any and All Outstanding
3% Convertible Senior Subordinated Notes due 2038
CUSIP No. 671040 AG8
CUSIP No. 671040 AH6

     This Supplement No. 1 to Offer to Purchase (this Supplement No. 1) supplements and amends the Offer to Purchase dated June 17, 2010 (the “Original Offer to Purchase”) relating to an offer by OSI Pharmaceuticals, Inc., a Delaware corporation (the “Company,” “we,” “us” and “our”), to purchase for cash, on the terms and subject to the conditions set forth in the Original Offer to Purchase (as supplemented and amended by this Supplement No. 1 and as it may be further supplemented and amended from time to time, the “Offer to Purchase”), any and all of its 3% Convertible Senior Subordinated Notes due 2038 (the “Notes”) at a purchase price of $1,000 per $1,000 principal amount of Notes plus accrued and unpaid interest to, but excluding, the applicable Purchase Date. You should carefully read the Original Offer to Purchase and this Supplement No. 1 to fully understand the terms of the Offer. Capitalized terms used and not otherwise defined in this Supplement No. 1 have the meanings given to them in the Original Offer to Purchase.

     This Supplement No. 1 supplements and amends information in the Original Offer to Purchase, and, accordingly, to the extent inconsistent, the information in this Supplement No. 1 supersedes the information contained in the Original Offer to Purchase. Any statement that is amended hereby shall not be deemed to constitute a part of the Offer to Purchase except as amended by this Supplement No. 1. Information contained in the Original Offer to Purchase and not addressed in this Supplement No. 1 remains unchanged.

     The Original Offer to Purchase is hereby supplemented and amended by inserting the following paragraph after the sixth full paragraph of Section 3.3 of the Original Offer to Purchase entitled “Conversion Rights of the Notes”:

In accordance with the foregoing, if a Holder surrenders its Notes for conversion on or before July 20, 2010, the Holder will receive approximately $1,145.91 per $1,000 principal amount of Notes. If a Holder surrenders its Notes for conversion after July 20, 2010, the Holder will receive approximately $778.91 per $1,000 principal amount of Notes.

     You should review the Offer to Purchase carefully and consult with your own financial and tax advisors. You must make your own decision as to whether or not to tender your Notes for purchase and, if so, the amount of Notes to tender. None of the Company, the Acquirer, their respective Boards of Directors, their respective employees, the Trustee, the Paying Agent or the

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Conversion Agent are making any representation or recommendation to any Holder as to whether or not to tender that Holder’s Notes.

The Paying Agent and the Conversion Agent is:
The Bank of New York Mellon,

By Hand or Overnight Delivery:	For Information:	By Facsimile:
The Bank of New York Mellon	Please call Sherma Thomas at	(212) 815-2742
Attention: Reorg Dept.	212-815-5283 if you have any
101 Barclay Street — 7E	questions	Attention:
New York, New York 10286		Dianne Amoroso

Additional copies of the Offer to Purchase may be obtained from the Paying Agent at its address set forth above.

Neither the Securities and Exchange Commission nor any state securities commission nor any other regulatory authority has approved or disapproved of these transactions or determined if this statement is truthful or complete. Any representation to the contrary is a criminal offense.

June 29, 2010

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EX-99.A.5.C

Exhibit (a)(5)(C)

OSI PHARMACEUTICALS, INC.

2% Convertible Senior Subordinated Notes Due December 15, 2025

Amended and Restated Form of Fundamental Change Repurchase Notice

THIS AMENDED AND RESTATED FORM OF FUNDAMENTAL CHANGE PURCHASE NOTICE (THE “ELECTION FORM”) SUPERSEDES ANY PREVIOUS FORM OF FUNDAMENTAL CHANGE PURCHASE NOTICE (THE “ORIGINAL ELECTION FORM”) WITH RESPECT TO THE FUNDAMENTAL CHANGE PURCHASE RIGHT (AS DEFINED IN AND IN ACCORDANCE WITH THE OFFER TO PURCHASE DATED JUNE 17, 2010 (THE “ORIGINAL OFFER TO PURCHASE”), AS AMENDED BY SUPPLEMENT NO. 1 TO OFFER TO PURCHASE DATED JUNE 29, 2010, RELATING TO THE OFFER BY OSI PHARMACEUTICALS, INC. (THE “COMPANY”) TO PURCHASE FOR CASH ANY AND ALL OF ITS 2% CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2025). THIS ELECTION FORM AMENDS AND RESTATES THE ORIGINAL ELECTION FORM SOLELY TO REQUIRE THAT A HOLDER SPECIFY THE FUNDAMENTAL CHANGE WITH REGARD TO WHICH IT IS ELECTING TO EXERCISE ITS FUNDAMENTAL CHANGE PURCHASE RIGHT. IN ALL OTHER RESPECTS, THE ORIGINAL ELECTION FORM REMAINS UNCHANGED. IN ORDER TO EXERCISE ITS FUNDAMENTAL CHANGE PURCHASE RIGHT, A HOLDER MUST USE THIS ELECTION FORM AND MUST FILL OUT THIS ELECTION FORM IN ITS ENTIRETY.

The undersigned registered owner of this Security hereby acknowledges receipt of a notice from the Company pursuant to Section 3.09 of that certain Indenture (the “Indenture”), dated as of December 21, 2005, between the Company and The Bank of New York Mellon (f/k/a The Bank of New York), and requests and instructs the Company to repurchase the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Security and the Indenture on the Fundamental Change Repurchase Date at the Fundamental Change Repurchase Price, together with accrued and unpaid interest (including Additional Interest, if any), to, but not including, the Fundamental Change Repurchase Date, to the registered Holder hereof. All capitalized terms used that are not otherwise defined herein have the meanings ascribed to them in the Indenture and in the 2% Notes Fundamental Change Company Notice and Notice of Conversion, dated June 18, 2010.

This Election Form is submitted in connection with the following Fundamental Change (please check one):

Tender Offer Completion o Merger o Delisting o

Date:
	Signature (s)
	Signatures must be guaranteed by a qualified guarantor institution with membership in an approved signature guarantee program pursuant to Rule 17Ad-15 under the Securities Exchange Act of 1934.
	Signature Guaranty
Principal amount to be redeemed (in an integral Multiple of $1,000, if less than all):
Certificate number (if applicable):

NOTICE: The signature to the foregoing election must correspond to the name as written upon the face of this Security in every particular, without any alteration or change whatsoever.

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EX-99.A.5.D

Exhibit (a)(5)(D)

OSI PHARMACEUTICALS, INC.

3% Convertible Senior Subordinated Notes Due January 15, 2038

Amended and Restated Form of Fundamental Change Purchase Notice

THIS AMENDED AND RESTATED FORM OF FUNDAMENTAL CHANGE PURCHASE NOTICE (THE “ELECTION FORM”) SUPERSEDES ANY PREVIOUS FORM OF FUNDAMENTAL CHANGE PURCHASE NOTICE (THE “ORIGINAL ELECTION FORM”) WITH RESPECT TO THE FUNDAMENTAL CHANGE PURCHASE RIGHT (AS DEFINED IN AND IN ACCORDANCE WITH THE OFFER TO PURCHASE DATED JUNE 17, 2010 (THE “ORIGINAL OFFER TO PURCHASE”), AS AMENDED BY SUPPLEMENT NO. 1 TO OFFER TO PURCHASE DATED JUNE 29, 2010, RELATING TO THE OFFER BY OSI PHARMACEUTICALS, INC. (THE “COMPANY”) TO PURCHASE FOR CASH ANY AND ALL OF ITS 3% CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2038; THE ORIGINAL OFFER TO PURCHASE SO AMENDED, THE “OFFER TO PURCHASE”). THIS ELECTION FORM AMENDS AND RESTATES THE ORIGINAL ELECTION FORM SOLELY TO REQUIRE THAT A HOLDER SPECIFY THE FUNDAMENTAL CHANGE WITH REGARD TO WHICH IT IS ELECTING TO EXERCISE ITS FUNDAMENTAL CHANGE PURCHASE RIGHT. IN ALL OTHER RESPECTS, THE ORIGINAL ELECTION FORM REMAINS UNCHANGED. IN ORDER TO EXERCISE ITS FUNDAMENTAL CHANGE PURCHASE RIGHT, A HOLDER MUST USE THIS ELECTION FORM AND MUST FILL OUT THIS ELECTION FORM IN ITS ENTIRETY.

To:      The Bank of New York Mellon

The undersigned registered owner of this Security hereby acknowledges receipt of a notice from the Company pursuant to Section 3.08 of that certain Indenture (the “Indenture”), dated as of January 9, 2008, between the Company and The Bank of New York Mellon (f/k/a The Bank of New York), and requests and instructs the Company to purchase the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Security and the Indenture at the Fundamental Change Purchase Price, together with accrued and unpaid interest (including Additional Interest, if any), to, but not including, the Fundamental Change Purchase Date, to the registered Holder hereof. All capitalized terms used that are not otherwise defined herein have the meanings ascribed to them in the Indenture and in the Offer to Purchase.

This Election Form is submitted in connection with the following Fundamental Change (please check one):

Tender Offer Completion o Merger o Delisting o

Date:
	Signature (s)
	Signatures must be guaranteed by a qualified guarantor institution with membership in an approved signature guarantee program pursuant to Rule 17Ad-15 under the Securities Exchange Act of 1934.
	Signature Guaranty
Principal amount to be redeemed (in an integral Multiple of $1,000, if less than all):
Certificate number (if applicable):

NOTICE: The signature to the foregoing election must correspond to the name as written upon the face of this Security in every particular, without any alteration or change whatsoever.

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CORRESP

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June 29, 2010 Writer’s Direct Contact
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Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549-0303
Attention: Peggy Kim, Esq.

Special Counsel, Office of Mergers and Acquisitions

Re:  OSI Pharmaceuticals, Inc.
Schedule TO-I filed on June 17, 2010
SEC File No. 5-37954

Ladies and Gentlemen:

On behalf of OSI Pharmaceuticals, Inc. (“OSI”), we refer to OSI’s Tender Offer Statement on Schedule TO filed on June 17, 2010 and to the comments received from the staff (the “Staff”) of the Securities and Exchange Commission (the “Commission”) in a telefacsimile from Peggy Kim dated June 24, 2010. The discussion below is presented in the order of the numbered comments in the comment letter. Certain defined terms set forth in the letter are used as defined in the Schedule TO.

OSI has asked us to convey the following as their responses to the Staff.

Schedule TO-I

1. We note that you are offering to purchase the 2% and 3% Convertible Notes pursuant to the Indenture which provide the holders of the Convertible Notes with the right to require you to purchase all or part of the Convertible Notes upon the occurrence of a Fundamental Change, including the Astellas Tender Completion, the Merger with Astellas and the Delisting of your common stock. Please advise us as to whether you are conducting one tender offer or three separate tender offers. If you are conducting three separate tender offers in connection with each of these Fundamental Changes, please revise your document and describe any distinguishing features among the offers.

Peggy Kim, Esq.
June 29, 2010
Page Two

Response to Comment 1

     OSI is conducting a single tender offer for its 2% Convertible Notes and a separate single tender offer for its 3% Convertible Notes. Although each offer relates to three Fundamental Changes, the Fundamental Changes are part of a single integrated offering that results from the Merger Agreement (the “Merger Agreement”) dated May 16, 2010 between OSI, Astellas Pharma Inc. (“Astellas”), Astellas US Holding, Inc.(“AUSH”) and Ruby Acquisition, Inc. (“Ruby”) (a copy of the Merger Agreement is filed as Exhibit 2.1 to the Form 8-K filed by OSI on May 17, 2010 and as Exhibit (d)(1) to Amendment No. 9 (“Amendment No. 9”) to the Schedule TO filed by Astellas, AUSH and Ruby on May 17, 2010.)

     The SEC, through two interpretative releases, has identified five factors that must be considered in determining whether or not two offerings should be integrated. The five factors relevant to the question of integration include an analysis of whether (1) the different offerings are part of a single plan; (2) the offerings include the same class of security; (3) the offerings are made at or about the same time; (4) the same type of consideration is to be received; and (5) the offerings are made for the same general purpose. See Release No. 33-4434 (Dec. 6, 1961) and Release No. 33-4552 (Nov. 6, 1962). We believe that an analysis of these factors with respect to OSI’s tender offers leads to the conclusion that the three Fundamental Changes relating to OSI’s 2% Convertible Notes result in a single integrated offer to purchase those notes and that the three Fundamental Changes relating to OSI’s 3% Convertible Notes result in a single integrated offer to purchase those notes.

     Single Plan. Pursuant to the Merger Agreement, OSI approved Astellas’ tender offer for OSI’s common stock which resulted in a Fundamental Change on June 3, 2020; OSI further approved a merger between OSI and Ruby which resulted in a second Fundamental Change on June 8, 2010; and OSI agreed to take all actions necessary to delist its common stock from the NASDAQ Stock Market which resulted in a third Fundamental Change on June 18, 2010. The fact that each of these Fundamental Changes was expected to occur as a result of the Merger Agreement and was therefore part of a single plan is described in Astellas’ Amendment No. 9 and also in Amendment No. 6 to the Schedule 14D-9 filed by OSI on May 20, 2010.

     Same Class of Securities. The same class of securities, 2% Convertible Notes, is involved in OSI’s tender offer for the 2% Convertible Notes. The same class of securities, 3% Convertible Notes, is involved in OSI’s tender offer for the 3% Convertible Notes.

     Offerings Made at About the Same Time. OSI’s tender offers were commenced on the same day, June 17, 2010, regardless of which Fundamental Change they relate to.

Peggy Kim, Esq.
June 29, 2010
Page Three

     Same Type of Consideration. Cash is the only type of consideration that will be paid by OSI pursuant to its tender offers, and note holders will receive the same amount, principal plus accrued interest, for each Note they elect to put to OSI, regardless of which Fundamental Change the put relates to.

     Same General Purpose. OSI’s tender offers are intended to serve two general purposes which apply to all three Fundamental Changes. First, the offers are part of the transactions arising out of and contemplated by the Merger Agreement. Second, the offers are intended to fulfill OSI’s obligations under the indentures governing the Notes which give note holders the right to elect to put their Notes to OSI if Fundamental Changes occur. (The indenture for the 2% Convertible Notes was attached as Exhibit 4-1 to OSI’s Form 8-K filed on December 28, 2005. The indenture for the 3% Convertible Notes was attached as Exhibit 4-1 to OSI’s Form 8-K filed on June 15, 2008).

2. With a view towards disclosure, please advise us of the consequences to noteholders of tendering pursuant to the Tender Completion Purchase Right versus the Merger Purchase Right or the Delisting Purchase Right. For example, advise as to whether noteholders must specify which of the three Purchase Rights they are invoking and the effects of the different expiration dates. For instance, we note that interest payments on the 3% Convertible Notes will be paid on July 15 and that the Tender Completion Purchase Right expires on July 15, 2010, but that the other two Repurchase Rights expire on July 20 and 30. Therefore, it appears that noteholders who tender under the Tender Completion Purchase Right will not receive the interest payment, but noteholders who tender under the other two Purchase Rights will receive the interest payment. Please tell us whether noteholders will receive different interest payments and if so, how you are complying with Rule 13e-4(f)(8)(ii).

Response to Comment 2

     Except for the timing of the payments that will be made to tendering noteholders, and the calculation of accrued interest to such payment dates, there are no differences to noteholders tendering pursuant to the Tender Purchase Completion Right versus the Merger Purchase Right versus the Delisting Purchase Right. Holders of the 3% Convertible Notes who tender under the Tender Completion Purchase Right will receive the interest payment that is paid on July 15, 2010. This is confirmed by the following statement on the cover page of the Offer to Purchase relating to the 3% Convertible Notes: “Holders who validly tender their Notes prior to the Tender Completion Expiration Time will receive the “Tender Completion Purchase Price” equal to 100% of the aggregate principal amount of the Notes validly tendered and not withdrawn, plus accrued and unpaid interest to, but not including July 16, 2010 (the “Tender Completion Purchase Date”).” Because all note holders who elect to put their notes to OSI will receive principal plus accrued interest, we believe that the offers comply with Rule 13e-4(f)(8)(ii).

Peggy Kim, Esq.
June 29, 2010
Page Four

3. We note that you have filed the election for the 2% Convertible Notes. Please file the election form for the 3% Convertible Notes and any other tender offer materials as exhibits. Refer to Item 1016(a)(1) of Regulation M-A. Since it appears that noteholders may be required to specify under which Purchase Right (Tender Completion, Merger Purchase or Delisting) they are electing, please revise the election forms to clarify how they may indicate this, or advise us.

Response to Comment 3

     The election form for the 3% Convertible Notes will be filed as an exhibit to the Schedule TO, and the election forms for both the 2% Convertible Notes and the 3% Convertible Notes will be revised to clarify under which Purchase Right (Tender Completion, Merger Purchase or Delisting) note holders are electing to put their notes to OSI.

4. Please advise us as to how you are complying with Rule 14e-5.

Response to Comment 4

     Because the Offer for the 2% Convertible Notes is a single integrated offer and not three separate offers, we do not believe Rule 14e-5 applies to it. Similarly, because the Offer for the 3% Convertible Note is a single integrated offer and not three separate offers, we do not believe Rule 14e-5 applies to it.

5. Please revise the discussion of conversion rights by including an illustrative example so that investors may better understand the dollar amount of cash they will receive for each $1,000 in aggregate principal amount of Convertible Notes.

Response to Comment 5

     The Schedule TO will be revised to include illustrative examples of the dollar amounts of cash that each note holder will receive for each $1,000 principal amount of Convertible Notes it elects to convert.

On behalf of OSI, we hereby confirm to you OSI’s acknowledgement that:

1.	OSI is responsible for the adequacy and accuracy of the disclosure in its Tender Offer Statement on Schedule TO (the “Filing”);
2.	comments by the Staff or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the Filing; and

Peggy Kim, Esq.
June 29, 2010
Page Five

3. OSI may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

If you have any questions concerning the above responses, please do not hesitate to contact the undersigned at (212) 468-8082.

Sincerely,
 

/s/ John Hempill  

John Hempill