FIRST AMENDMENT TO CONSTRUCTION MORTGAGE DEED, ASSIGNMENT OF LEASES AND RENTS, SECURITY AGREEMENT AND FIXTURE FILING

Exhibit 10.3

OPEN END MORTGAGE TO SECURE PRESENT AND FUTURE LOANS UNDER CHAPTER 25 OF TITLE 34.

FIRST AMENDMENT TO CONSTRUCTION MORTGAGE DEED, ASSIGNMENT OF

LEASES AND RENTS, SECURITY AGREEMENT AND FIXTURE FILING

ALEXION MANUFACTURING LLC, as Mortgagor

in favor of

iSTAR FINANCIAL INC., as Mortgagee

Dated: July 18, 2007

Location: Town of Smithfield, Rhode Island

PREPARED BY AND WHEN RECORDED RETURN TO:

OPEN END MORTGAGE TO SECURE PRESENT AND FUTURE LOANS UNDER CHAPTER 25 OF TITLE 34.

FIRST AMENDMENT TO CONSTRUCTION MORTGAGE DEED, ASSIGNMENT OF

LEASES AND RENTS, SECURITY AGREEMENT AND FIXTURE FILING

THIS FIRST AMENDMENT TO CONSTRUCTION MORTGAGE DEED, ASSIGNMENT OF LEASES AND RENTS, SECURITY AGREEMENT AND FIXTURE FILING (the “Amendment ”) is made as of the 18th day of July, 2007 (the “Effective Date” ) by ALEXION MANUFACTURING LLC, a Delaware limited liability company, having an address at c/o Alexion Pharmaceuticals, Inc., 352 Knotter Drive, Cheshire, Connecticut 06410, (“ Mortgagor ”) in favor of i STAR FINANCIAL INC., a Maryland corporation, having an address at 1114 Avenue of the Americas, 27 ^th Floor, New York, New York 10036 (“ Mortgagee ”).

RECITALS

A. Mortgagor executed and delivered to Mortgagee that certain Construction Mortgage Deed, Assignment of Leases and Rents, Security Agreement and Fixture Filing, dated as of July 11, 2006, which Mortgage was recorded with the Records of Land Evidence of the Town of Smithfield in the State of Rhode Island in Book 504 at Page 14 (the “Mortgage” ), and which Mortgage encumbers among other things, the property legally described in Exhibit A . All terms not otherwise defined herein shall have the meanings ascribed to such terms in that certain Loan and Security Agreement dated as of July 11, 2006, by and between Mortgagor and Mortgagee, as amended by that First Amendment to Loan Agreement and Other Loan documents dated of even date herewith (together, the “Loan Agreement” ). All terms not otherwise defined herein shall have the meanings ascribed to such terms in the Loan Agreement.

B. Mortgagor has requested and Mortgagee has agreed to, among other things, increase the Loan to $44,000,000.00 and extend the term of the Loan.

C. Accordingly, Mortgagor and Mortgagee now desire to amend the Mortgage.

NOW THEREFORE, the Mortgage is hereby amended as follows:

1. All references to the Loan in the Mortgage whether expressed in writing or in numbers, are hereby modified from Twenty-Six Million and No/100 Dollars ($26,000,000.00) to Forty-Four Million and No/100 Dollars ($44,000,000.00). The Mortgage (as modified by this Amendment) shall secure the Loan as increased pursuant to the terms hereof.

2. All references in the Mortgage to the Maturity Date are changed from August 10, 2016 to August 10, 2017.

3. Section 2.3 of the Mortgage is hereby deleted in its entirety and the following is inserted in lieu thereof:

“2.3 Maximum Amount of Indebtedness . Notwithstanding anything to the contrary in the Mortgage, the maximum aggregate principal amount of indebtedness that is, or under any contingency may be, secured by the Mortgage (including Mortgagor’s obligation to reimburse advances made by Mortgagee), either at execution or at any time thereafter, including future advances which will be advanced from time to time from and after the date hereof and may include readvances of amounts repaid (the “ Secured Loan Amount ”), shall not exceed in the aggregate at any one time the outstanding amount of EIGHTY-EIGHT MILLION AND 00/100 DOLLARS ($88,000,000.00), plus amounts that Mortgagee expends after occurrence of an Event of Default to the extent that any such amounts shall constitute payment of (a) taxes, charges or assessments that may be imposed by law upon the Mortgaged Property; (b) premiums on insurance policies covering the Mortgaged Property; (c) expenses incurred in upholding the lien of the Mortgage, including the expenses of any litigation to prosecute or defend the rights and lien created by the Mortgage; or (d) any amount, cost or charge to which Mortgagee becomes subrogated, upon payment, whether under recognized principles of law or equity, or under express statutory authority; then in such event, such amounts or costs, together with interest thereon, shall be added to the indebtedness secured hereby and shall be secured by the Mortgage.

All persons and entities with any interest in the Mortgaged Property or about to acquire any such interest should be aware that the Mortgage secures more than the stated principal amount of the Note and interest thereon; the Mortgage secures any and all other amounts which may become due under the Note or other document or instrument evidencing, securing or otherwise affecting the indebtedness, including, without imitation, any and all amounts expended by Mortgagee upon an Event of Default to operate, manage or maintain the Mortgaged Property or to otherwise protect the Mortgaged Property or the lien of the Mortgage.”

4. Section 9.2 of the Mortgage is hereby deleted in its entirety and the following is inserted in lieu thereof:

“9.2 Rhode Island Open-End Mortgage Provisions . The Mortgage permits and secures any and all current and future advances to the Mortgagor evidenced by (or pursuant to) any one or more of the following: the Note, the Loan Documents or other documents evidencing the Obligations or the Indebtedness, such other note or notes as may be signed by Mortgagor payable to Mortgagee and such other agreement(s) as may be entered into by Mortgagor with the Mortgagee, and signed by Mortgagor. The unpaid principal balance of indebtedness outstanding under the Mortgage shall at no time exceed $88,000,000.00. Mortgagee will accept notices pursuant to Sections 34-25-10(b) and 34-25-11 of the General Laws of the State of Rhode Island, 1956, Reenactment of 1995, as amended, at the address specified on page 1 of the Mortgage.”

5. Except as expressly set forth above, all terms and conditions of the Mortgage shall remain unchanged and in full force and effect.

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SIGNATURE PAGE FOLLOWS.]

IN WITNESS WHEREOF , Mortgagor has executed this Amendment effective