Exhibit 10.53

PART-TIME EMPLOYMENT AGREEMENT

        This Part-Time Employment Agreement (this "Agreement"), dated as of
January 1, 2004 is entered into by and between Melvin D. Booth (the "Employee")
and MedImmune, Inc., a Delaware corporation (the "Company").

Recitals

        A.    The Employee has been employed by the Company as its President and
Chief Operating Officer under the terms of an Employment Agreement, dated as of
August 15, 2002 (the "Prior Employment Agreement") which is being terminated
pursuant to this Agreement effective as of the close of business on December 31,
2003; and

        B.    The Company desires to enter into a part-time employment
relationship with Employee, and Employee wishes to accept such part-time
employment relationship, upon the terms and conditions set forth in this
Agreement, effective as of January 1, 2004.

        In consideration of and in reliance upon the foregoing and the
covenants, obligations and agreements contained herein, the Company and Employee
hereby agree as follows:

Agreement

        1.    Employment.    The Prior Employment Agreement is terminated
effective as of the close of business on December 31, 2003. The Company hereby
employs the Employee, and the Employee hereby accepts part-time employment by
the Company effective as of January 1, 2004, on the terms and conditions set
forth in this Agreement.

        2.    Term.    Subject to the provisions for early termination, the
employment of the Employee hereunder will be for the period commencing on
January 1, 2004 and ending on December 31, 2004. Such period may be extended by
mutual written consent of the Company and the Employee. The period of the
Employee's employment under this Agreement, as it may be terminated or extended
from time to time as provided herein, is referred to hereafter as the
"Employment Period."

        3.    Duties and Responsibilities.    During the Employment Period, the
Employee's duties and responsibilities to the Company will be as set forth on
Annex A, a copy of which is attached. The Employee also agrees that during the
Employment Period he will provide the Company with assistance with respect to
any issues involving the Company as to which he may have knowledge based on any
specific activities undertaken while he was President and Chief Operating
Officer or as is reasonably requested by the Chief Executive Officer of the
Company. During the Employment Period, the Employee will report to the Chief
Executive Officer of the Company and the Employee agrees he will faithfully
perform his duties and responsibilities to the Company under the supervision of,
and in the manner prescribed by, the Chief Executive Officer of the Company. The
Company will provide the Employee with such equipment and supplies (including,
but not limited to, a computer and cell phone) as it determines appropriate for
the Employee to perform his duties and responsibilities hereunder. The Company
will also provide such administrative assistance as the Employee may need to
perform his assigned tasks for the Company. The Employee will submit regular
reports (monthly) on a written and/or oral basis to the Chief Executive Officer
concerning the Employee's activities that month. The Employee agrees to take
such actions reasonably requested by the Chief Executive Officer from time to
time to remove the Employee from positions of authority within the Company held
by the Employee when the Employee was President and Chief Operating Officer. The
Employee agrees to comply with all Company policies applicable to employees of
the Company including, but not limited to, the Company's Confidential
Information and Securities Trading Policy.

        4.    Time to be Devoted to Employment.    During the Employment Period,
the Employee will devote such time as is necessary to perform his duties and
responsibilities as a part-time employee but in no

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event will Employee be required to work more than 20 hours per week or 32 hours
per month. It is initially anticipated that the Employee will be available one
day per month, either on-site or available by phone and e-mail, and it is the
Company's responsibility to direct the Employee to undertake certain activities
during the time the Employee will make himself available. For clarity, the
Employee's obligations as a member of the Company's Board of Directors (or any
committee of the Board of Directors) will not count towards these maximum hour
requirements.

        5.    Compensation; Reimbursement.    

        (a)    Base Salary.    During the Employment Period, the Company will
pay the Employee at the rate of $50,000 per annum, payable in semimonthly pay
periods. For any such services rendered as a part-time employee during any
calendar month in excess of 8 hours, Employee shall be compensated at the lesser
of $500 per hour or $3,500 per day. The Employee will remain on the Company's
payroll and will have all applicable taxes withheld and will provide the Company
with time sheets and accounts for all hours worked. For clarity, hours spent by
the Employee in his capacity as a member of the Board of Directors (or any
committee of the Board of Directors) will not be subject to compensation under
this Section 5(a). If the Employee is asked to serve as a member of the board of
directors, an officer or in another similar role of any entity (other than the
Company or its subsidiaries) as a representative or designee of the Company or
any of its subsidiaries (e.g., as a board member of a MedImmune Ventures, Inc.
portfolio company), the Employee will be compensated at the annual rate of
$30,000 for that service (pro-rated for any partial year period during which the
Employee is serving in such role and payable in equal installments during
semimonthly pay periods during the Employment Period), and such service will not
count towards the employee's maximum hour requirements set forth in Section 4 or
otherwise included in the calculation of the number of hours for which the
Employee is otherwise compensated under this Section 5(a). The Employee
acknowledges that, in accordance with Company policy, any compensation offered
or received by the Employee for service with an entity as a representative or
designee of the Company or any of its subsidiaries must be transferred to the
Company or, if the compensation is in the nature of a personal right that cannot
easily be transferred, must be held for the benefit of the Company and exercised
at the direction of the Company's Chief Executive Officer.

        (b)    Benefits.    During the Employment Period, the Employee will be
entitled to participate in such employee benefit plans or programs of the
Company, and will be entitled to such other fringe benefits, as are from time to
time made available by the Company generally to part-time employees with the
Employee's number of work hours, position, tenure, salary, age, health and other
qualifications. The Employee acknowledges and agrees that the Company does not
guarantee the adoption or continuance of any particular employee benefit plan or
program or other fringe benefit during the Employment Period, and participation
by the Employee in any such plan or program will be subject to the rules and
regulations applicable thereto. As an employee member of the Board of Directors,
the Employee will not be entitled to compensation benefits available to
non-employee board members.

        (c)    Stock Options.    The Employee is currently a party to stock
option agreements entered into with the Company for stock options granted on
October 5, 1998, February 24, 1999, February 17, 2000, February 15, 2001,
February 21, 2002 and February 20, 2003 (each an "Option Agreement" and
collectively, the "Option Agreements"). The parties agree and the Employee
understands and acknowledges that the Option Agreements are hereby amended so
that, notwithstanding anything in the Option Agreements to the contrary,
(1) stock options that are not vested as of December 31, 2003 will be deemed to
be immediately forfeited, (2) stock options that are vested under these
agreements as of December 31, 2003 may be exercised by the Employee until
90 days after the expiration of this Agreement and (3) if the Employee is
terminated by the Company for any reason that would have constituted "Cause" as
defined in the Prior Employment Agreement or upon occurrence of an event

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described in Section 7(b) (for the purpose of this Agreement any such reason
shall be deemed "Cause"), all stock options will immediately be forfeited upon
termination

        (d)    Expenses.    During the Employment Period, the Company will
(1) reimburse the Employee, in accordance with the practices in effect from time
to time for other staff personnel of the Company at the same level at which
Employee was generally entitled to be reimbursed before he became a part-time
employee, for all reasonable and necessary traveling expenses and other
disbursements incurred by the Employee for or on behalf of the Company in the
performance of the Employee's duties hereunder, upon presentation by the
Employee to the Company of appropriate vouchers, (2) provide funding for the
Employee's travel to and attendance at professional meetings, as approved by the
Chief Executive Officer of the Company and (3) provide the required tools and
materials to Employee to perform his duties. For clarity, time spent for any
travel to or from the Company's premises will not be included in determining the
number of hours worked by the Employee or for which the Employee is entitled to
compensation under Section 4 or Section 5(a).

        6.    Termination of Employment.    The Employee's employment with the
Company during the Employment Period may be terminated (a) on account of the
death of the Employee, (b) on account of a voluntary termination by the Employee
for any reason or (c) by the Company for cause, which shall be defined as in
Employee's Prior Employment Agreement, as amended herein.

        7.    Effect of Termination of Employment.    

        (a)   Upon the termination of the Employee's employment during the
Employment Period, neither the Employee nor the Employee's beneficiaries or
estate will have any further rights or claims against the Company under this
Agreement except the right to receive (1) the unpaid portion of the base salary
provided for in Section 5(a) hereof, (2) payment of his accrued but unpaid
rights in accordance with the terms of any incentive compensation, stock option,
retirement, employee welfare or other employee benefit plans or programs of the
Company in which the Employee is then participating in accordance with
Section 5(b) or Section 5(c) hereof and (3) reimbursement for any expenses for
which the Employee shall not have been previously reimbursed as provided in
Section 5(d) hereof.

        (b)   In the event that, subsequent to termination of employment
hereunder, the Employee (1) breaches any of the provisions of Section 8 or
Section 9 hereof or (2) directly or indirectly makes or facilitates the making
of any adverse public statements or disclosures with respect to the business or
securities of the Company, all payments and benefits to which the Employee may
otherwise have been entitled pursuant to this Agreement shall immediately
terminate and be forfeited, and any portion of such amounts as may have been
paid to the Employee shall forthwith be returned to the Company.

        8.    Disclosure of Information.    The Employee will not, at any time
during or after the Employment Period, disclose to any person, firm, corporation
or other business entity, except as required by law, any non-public information
concerning the technology, know-how, trade secrets, business, products, clients
or affairs of the Company or any subsidiary of the Company for any reason or
purpose whatsoever, nor will the Employee make use of any of such non-public
information for personal purposes or for the benefit of any person, firm,
corporation or other business entity except the Company or any subsidiary of the
Company; provided, however, the Employee may disclose the terms of this
Agreement to a prospective employer, attorney, accountant, financial advisor or
immediate family member of the Employee.

        9.    Restrictive Covenant.    

        (a)   The Employee hereby acknowledges and recognizes that, during the
Employment Period, the Employee will be privy to trade secrets and confidential
proprietary information critical to the Company's business and, accordingly, the
Employee agrees that, in consideration of the benefits to be received by the
Employee hereunder, the Employee will not, during the Employment Period,
(1) engage in any activity that would be directly competitive with a specific
product or product

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candidate being researched, developed or marketed by the Company or any
subsidiary of the Company (a "Competing Business"), it being understood that
this restriction is not intended to be a general prohibition on the ability of
the Employee to work in the fields of oncology, infectious disease or
autoimmunity or (2) induce other employees of the Company or any subsidiary of
the Company to terminate their employment with the Company or any subsidiary of
the Company or to engage in any Competing Business. This obligation will be in
addition to any similar obligation to which the Employee is otherwise subject.
Notwithstanding the foregoing, the term "Competing Business" shall not include
any business or activity that was not conducted by the Company or any subsidiary
of the Company during the Employment Period.

        (b)   The Employee understands that the foregoing restrictions may limit
the ability of the Employee to earn a livelihood in a business similar to the
business of the Company, but nevertheless believes that the Employee has
received and will receive sufficient consideration and other benefits, as an
employee of the Company and as otherwise provided hereunder, to justify such
restrictions which, in any event (given the education, skills and ability of the
Employee), the Employee believes would not prevent the Employee from earning a
living.

        10.    Intellectual Property.    Employee will promptly disclose, grant
and assign to Company, for its sole use and benefit, all inventions,
improvements, technical information and suggestions relating in any way to the
business of Company which Employee may develop or acquire during the term of
this Agreement, together with all patent applications, letters patent,
copyrights and reissues thereof that may at any time be granted for or upon any
such invention, improvement or technical information.

        11.    Enforcement.    It is the desire and intent of the parties hereto
that the provisions of this Agreement be enforceable to the fullest extent
permissible under the laws and public policies applied in each jurisdiction in
which enforcement is sought. Accordingly, to the extent that a restriction
contained in this Agreement is more restrictive than permitted by the laws of
any jurisdiction where this Agreement may be subject to review and
interpretation, the terms of such restriction, for the purpose only of the
operation of such restriction in such jurisdiction, will be the maximum
restriction allowed by the laws of such jurisdiction and such restriction will
be deemed to have been revised accordingly herein.

        12.    Remedies; Survival.    

        (a)   The Employee acknowledges and understands that the provisions of
the covenants contained in Sections 8 and 9 hereof, the violation of which
cannot be accurately compensated for in damages by an action at law, are of
crucial importance to the Company, and that the breach or threatened breach of
the provisions of this Agreement would cause the Company irreparable harm. In
the event of a breach or threatened breach by the Employee of the provisions of
Section 8 or 9 hereof, the Company will be entitled to an injunction restraining
the Employee from such breach. Nothing herein contained will be construed as
prohibiting the Company from pursuing any other remedies available for any
breach or threatened breach of this Agreement.

        (b)   Notwithstanding anything contained in this Agreement to the
contrary, the provisions of Sections 8 or 9 hereof will survive the expiration
or other termination of this Agreement until, by their terms, such provisions
are no longer operative.

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        13.    Notices.    Notices and other communications hereunder will be in
writing and will be delivered personally or sent by air courier or first class
certified or registered mail, return receipt requested and postage prepaid,
addressed as follows:

if to the Employee:         Melvin D. Booth
8318 Woodlea Mill Rd
McLean VA 22102
and if to the Company:
 
Before March 2004:
 
 
MedImmune, Inc.
35 West Watkins Mill Road
Gaithersburg, Maryland 20878
Attention: Chief Executive Officer
 
 
After March 2004:
 
 
MedImmune, Inc.
One MedImmune Way
Gaithersburg, Maryland 20878
Attention: Chief Executive Officer

        All notices and other communications given to any party hereto in
accordance with the provisions of this Agreement will be deemed to have been
given on the date of delivery, if personally delivered; on the business day
after the date when sent, if sent by air courier; and on the third business day
after the date when sent, if sent by mail, in each case addressed to such party
as provided in this Section 13 or in accordance with the latest unrevoked
direction from such party.

        14.    Binding Agreement; Benefit.    The provisions of this Agreement
will be binding upon, and will inure to the benefit of, the respective heirs,
personal representatives, successors and assigns of the parties hereto.

        15.    Governing Law.    This Agreement will be governed by and
enforceable in accordance with the laws of the State of Maryland applicable to
contracts executed and performed within such state, without giving effect to the
principles of conflict of laws thereof. The Company and the Employee agree that
any claims concerning the rights and obligations of the parties or any other
issue arising under this Agreement shall be brought in the Circuit Court for
Montgomery County or the United States District Court for the District of
Maryland, and that such courts shall have exclusive jurisdiction over litigation
involving any such claims. The Company and the Employee agree to submit to the
jurisdiction of such courts and that they will not raise lack of personal
jurisdiction or inconvenient forum as defenses in any such litigation.

        16.    Waiver of Breach.    The waiver by either party of a breach of
any provision of this Agreement by the other party must be in writing and will
not operate or be construed as a waiver of any subsequent breach by such other
party.

        17.    Entire Agreement; Amendments.    This Agreement (including
Annex A) and the Option Agreements (as amended by this Agreement) contain the
entire agreement between the parties with respect to the subject matter hereof
and supersede all prior agreements or understandings among the parties with
respect thereof, including, without limitation, the Employment Agreement and any
other employment or similar agreement between the Company and the Employee. This
Agreement may be amended only by an agreement in writing signed by the parties
hereto.

        18.    Headings.    The section headings contained in this Agreement are
for reference purposes only and will not affect in any way the meaning or
interpretation of this Agreement.

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        19.    Severability.    Any provision of this Agreement that is
prohibited or unenforceable in any jurisdiction will, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction will not invalidate or render unenforceable
such provision in any other jurisdiction.

        20.    Assignment.    This Agreement is personal in its nature and the
parties hereto will not, without the consent of the other, assign or transfer
this Agreement or any rights or obligations hereunder; provided, that the
provisions hereof (including, without limitation, Sections 8 or 9) will inure to
the benefit of, and be binding upon, each successor of the Company, whether by
merger, consolidation, transfer of all or substantially all of its assets or
otherwise.

[Remainder of this page intentionally left blank.]

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        The parties have duly executed this Agreement effective as of the date
first above written.

EMPLOYEE:
 
COMPANY:
 
 
MEDIMMUNE, INC.
/s/: Melvin D. Booth
Melvin D. Booth
 
By:
 
/s/ David M. Mott
David M. Mott
Chief Executive Officer

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