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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. 1)
Alexion Pharmaceuticals, Inc.
(Name of Issuer)
Common Shares
(Title of Class of Securities)
015351109
(CUSIP Number)
December 31, 2004
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
/_X_/ Rule 13d-1(b)
/___/ Rule 13d-1(c)
/___/ Rule 13d-1(d)
* The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which
would alter disclosures provided in a prior cover page.
The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities
Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of
that section of the Act but shall be subject to all other provisions of the
Act (however, see the Notes).
Potential persons who are to respond to the collection of information
contained in this form are not required to respond unless the form displays
a currently valid OMB control number. SEC 1745 (02-02)
CUSIP No. 015351109 13G
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
RS Investment Management Co. LLC
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a)/ /
(b)/ /
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
Delaware
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NUMBER OF 5 SOLE VOTING POWER
SHARES -0-
BENEFICIALLY ---------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH -1,699,750-
REPORTING ---------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH -0-
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8 SHARED DISPOSITIVE POWER
-1,699,750-
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
-1,699,750-
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10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See
Instructions)
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
6.1%
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12 TYPE OF REPORTING PERSON (See Instructions)
OO, HC
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CUSIP No. 015351109 13G
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
RS Investment Management, L.P.
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a)/ /
(b)/ /
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
California
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NUMBER OF 5 SOLE VOTING POWER
SHARES -0-
BENEFICIALLY ---------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH -1,696,980-
REPORTING ---------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH -0-
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8 SHARED DISPOSITIVE POWER
-1,696,980-
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
-1,696,980-
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10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See
Instructions)
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
6.1%
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12 TYPE OF REPORTING PERSON (See Instructions)
PN, IA
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CUSIP No. 015351109 13G
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1 NAME OF REPORTING PERSONS
IRS IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
George R. Hecht
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
(a)/ /
(b)/ /
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3 SEC USE ONLY
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4 CITIZENSHIP OR PLACE OF ORGANIZATION
California
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NUMBER OF 5 SOLE VOTING POWER
SHARES -0-
BENEFICIALLY ---------------------------------------
OWNED BY 6 SHARED VOTING POWER
EACH -1,699,750-
REPORTING ---------------------------------------
PERSON 7 SOLE DISPOSITIVE POWER
WITH -0-
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8 SHARED DISPOSITIVE POWER
-1,699,750-
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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
-1,699,750-
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10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See
Instructions)
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
6.1%
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12 TYPE OF REPORTING PERSON (See Instructions)
HC, IN
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CUSIP No. 015351109 13G
ITEM 1.
(a) The name of the issuer is Alexion Pharmaceuticals,
Inc. (the "Issuer").
(b) The principal executive office of the Issuer is located at:
352 Knotter Drive, Cheshire, CT 06511.
ITEM 2.
(a-c) See Annex I for information on the persons filing this
statement (collectively, the "Filers")
(d) This statement relates to shares of common stock of the Issuer
(the "Stock").
(e) The CUSIP number of the Stock is 015351109.
CUSIP No. 015351109 13G
ITEM 3. If this statement is filed pursuant to rules 240.13d-1(b) or
240.13d-2(b) or (c), check whether the person filing is a:
(a) ___ Broker or dealer registered under section 15 of the Act (15
U.S.C. 78o).
(b) ___ Bank as defined in section 3(a)(6) of the Act (15 U.S.C.
78c).
(c) ___ Insurance company as defined in section 3(a)(19) of the Act
(15 U.S.C. 78c).
(d) ___ Investment company registered under section 8 of the
Investment Company Act of 1940 (15 U.S.C. 80a-8).
(e) _X*_ An investment adviser in accordance with 240.13d-
1(b)(1)(ii)(E). *RS Investment Management, L.P. is a registered
investment adviser.
(f) ___ An employee benefit plan or endowment fund in accordance
with 240.13d-1(b)(1)(ii)(F).
(g) _X*_ A parent holding company or control person in accordance
with 240.13d-1(b)(1)(ii)(G).
*RS Investment Management Co. LLC is the general partner
of RS Investment Management, L.P. George R.
Hecht is a control person of RS Investment Management
Co. LLC and RS Investment Management, L.P.
(h) ___ A savings association as defined in section 3(b) of the
Federal Deposit Insurance Act (12 U.S.C. 1813).
(i) ___ A church plan that is excluded from the definition of an
investment company under section 3(c)(14) of the Investment Company Act of
1940 (15 U.S.C. 80a-3).
(j) ___ Group, in accordance with rule 240.13d-1(b)(1)(ii)(J)
CUSIP No. 015351109 13G
ITEM 4. OWNERSHIP
See Items 5-9 and 11 on the cover page for each Filer.
ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following /__/.
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON
RS Investment Management Co. LLC is the parent company of registered
investment advisers whose clients have the right to receive or the
power to direct the receipt of dividends from, or the proceeds
from the sale of, the Stock. No individual client's holdings of
the Stock are more than five percent of the outstanding Stock.
RS Investment Management, L.P. is a registered investment adviser and a
managing member of registered investment advisers. RS Investment
Management Co. LLC is the General Partner of RS Investment Management,
L.P. George R. Hecht is a control person of RS Investment Management
Co. LLC and RS Investment Management, L.P.
CUSIP No. 015351109 13G
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED
THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY
Not applicable.
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
Not applicable.
ITEM 9. NOTICE OF DISSOLUTION OF GROUP
Not applicable.
ITEM 10. CERTIFICATION
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired and are held in the ordinary
course of business and were not acquired and are not held for the purpose
of or with the effect of changing or influencing the control of the issuer
of the securities and were not acquired and are not held in connection with
or as a participant in any transaction having that purpose or effect.
SIGNATURE
After reasonable 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.
Dated: February 14, 2005
RS INVESTMENT MANAGEMENT CO. LLC
By: __________________________
Terry R. Otton
Chief Operating Officer
RS INVESTMENT MANAGEMENT, L.P.
By: __________________________
Terry R. Otton
Chief Operating Officer
CUSIP No. 015351109 13G
GEORGE R. HECHT
__________________________
George R. Hecht
EXHIBIT A
JOINT FILING AGREEMENT
The undersigned hereby agree that they are filing this statement jointly
pursuant to Rule 13d-1(f)(1). Each of them is responsible for the timely
filing of the Schedule 13G and any amendments thereto, and for the
completeness and accuracy of the information concerning such person
contained therein; but none of them is responsible for the completeness or
accuracy of the information concerning the other persons making the filing,
unless such person knows or has reason to believe that such information is
accurate.
Dated: February 14, 2005
RS INVESTMENT MANAGEMENT CO. LLC
By: __________________________
Terry R. Otton
Chief Operating Officer
RS INVESTMENT MANAGEMENT, L.P.
By: __________________________
Terry R. Otton
Chief Operating Officer
CUSIP No. 015351109 13G
GEORGE R. HECHT
__________________________
George R. Hecht
Annex I
The filers are:
I.
(a) RS Investment Management Co. LLC is a Delaware Limited Liability
Company.
(b) holding company
II.
(a) RS Investment Management, L.P. is a California Limited
Partnership.
(b) registered investment adviser
III.
(a) George R. Hecht is a control person of RS Investment Management
Co. LLC and RS Investment Management, L.P.
(b) individual