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Exhibit 4.14
 Amendment Agreement to the Participation Agreements
  1.
    
    BayernKapital Risikokapitalbeteiligungs GmbH, Altstadt 72, 84028 Landshut
 BayernKapital
 2.
    
    Technologie Beteiligungsfonds Bayern GmbH & Co. KG, Königinstralße 17, 80539 München/Munich
 Technofonds Bayern
 3.
    
    Micromet AG, Staffelseestr. 2, 81477 München/Munich, eingetragen im Handelsregister des
Registergericht München unter/registered with the Commercial Register of the Munich Local
Court under HR B 133 040,
 Micromet TU
 Preamble
 A.
    
    On 30 May/1 July 1997, BayernKapital and Micromet have entered into a participation
agreement, ending 12/31/2006, establishing a silent partnership among BayernKapital and
Micromet with a contribution of BayernKapital with a nominal value of EUR 893,073.53. On 7
July 1999/17 January 2000, Technofonds Bayern and Micromet have entered into a participation
agreement, ending 12/31/2008, establishing a silent partnership among Technofonds Bayern and
Micromet with a contribution of Technofonds Bayern with a nominal value of EUR 1,661,698.61.B.
    
    The silent partnership agreements mentioned in sec. A. above were registered with the
Commercial Register on 7 September 2000 pursuant to § 292(2) No. 1 German Stock Corporation
Act.C.
    
    The shareholders of Micromet AG intend to contribute their shares in the Company to Micromet,
Inc., with its registered seat in Delaware, USA. This company shall henceforth act under the
name Micromet, Inc., Delaware, USA. To this end, on 6 January 2006, Micromet AG entered into
an Agreement and Plan of Merger and Reorganization with Micromet, Inc., Delaware, CancerVax
Corporation, Delaware and Carlsbad Acquisition Corporation, Delaware with the consent of
BayernKapital and Technofonds Bayern (hereinafter also referred to as Merger Agreement).
The parties intend to amend the participation agreements in light of the forthcoming change of
the shareholder structure.
 1.




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NOW, THEREFORE
 §1
Repayment of the
Participation Agreements
 1.
    
    The parties are in agreement that the consummation of the transactions contemplated in the
Merger Agreement does not have any impact on the term of the Participation Agreements among
the parties except as provided for in § 1(2) below, wherefore § 4(4) of such Participation
Agreements shall not be applicable in case this agreement becomes effective (§ 4). The
Participation Agreements shall remain in force for a defined term as provided for in the
Participation Agreements (until 12/31/2006 and 12/31/2008, respectively), except as provided
for in § 1(2) below.
 2.
    
    The parties are in agreement that in the event of the consummation of one or more further
rounds of financing (as defined below) of Micromet, Inc. or a successor in interest in case of
merger (hereinafter collectively referred to as Micromet, Inc.) after the consummation of
the transactions contemplated in the Merger Agreement and after consummation of the financing
agreed in the Investment Agreement Micromet AG October 11, 2005 (hereinafter referred to as
Further Financing), the silent participations of BayernKapital and Technofonds Bayern will
be terminated, completely or partially, pursuant to the following provisions. Consummation of
a further round of financing in this context shall be defined as the raising of further equity
capital in the course of a share capital increase or as contributions to the equity capital
after acquisition of shares as well as the issuance of loans with stock option, convertible
bonds, convertible loans or comparable instruments convertible into equity or with attached
equity options; provided, however, that in this context the issuance of convertible bonds,
convertible loans or comparable instruments convertible into equity in the course of
co-operations of Micromet, Inc. and/or Micromet AG as well as the raising of pre-financing for
bridging the financing requirements until the consummation of a further round of financing
shall expressly not be considered as the consummation of a further round of financing.
 2.1
    
    20% of all financing capital of whatever kind raised by Micromet, Inc. in the
course of the Further Financings (including such financing capital raised from
Investors of the Further Financing or from existing shareholders, even if such capital
consists in non-equity means, or raised in the course of a pre-financing for bridging
the financing requirements until the consummation of a further round of financing, to
the extent that these are not repaid in connection with the consummation of the ensuing
Further Financing), respectively, shall be used for the early repayment to
BayernKapital and Technofonds Bayern in accordance with this § 1(2), but not more than
an amount equal to the sum of the total outstanding claims of BayernKapital and
Technofonds Bayern (nominal value not repaid plus fixed compensation accrued but not
paid plus unpaid final compensation as of the time of the consummation of the
respective Further Financing) (hereinafter referred to as Total Claim) at the time of
the
 2.




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consummation of the respective Further Financing (hereinafter referred to as
Repayment Amount).
 2.2
    
    If the Repayment Amount of the respective Further Financing is not sufficient
to satisfy the Repayment Amount, then the Repayment Amount shall first be used to pay
(in full or in part) to BayernKapital and Technofonds Bayern the fixed compensation
accrued but not paid; the Repayment Amount remaining after such payments shall then be
used to repay (in full or in part) the nominal value of the silent partnership of
BayernKapital not repaid together with the corresponding final compensation agreed in
the contract as of the time of the consummation of the respective Further Financing;
the Repayment Amount remaining after such payments shall finally be used to repay (in
full or in part) the not repaid nominal value of the silent partnership of Technofonds
Bayern together with the corresponding final compensation agreed in the contract as of
the time of the consummation of the respective Further Financing. In part shall mean
that the Repayment Amount shall be split proportionately among the nominal value and
the corresponding final compensation. The silent participation terminates upon the
consummation of the Further Financing to the extent that the Repayment Amount is so
allocated to the nominal value.2.3
    
    The payments under this § 1(2) shall become due for payment within 14 days
after the receipt by Micromet, Inc. of the financing capital out of the respective
Further Financing. To the extent that the nominal values of the Participation
Agreements among the parties are not to be repaid early under this § 1(2), the fixed
term provided for in the Participation Agreements shall remain unaffected; the nominal
values which are not to be repaid early under this § 1(2) become due for repayment to
BayernKapital and Technofonds Bayern, respectively, after the end of such fixed term
together with the corresponding final compensation agreed in the contracts.
 §2
Final Compensation
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§3
Further Amendments
 1.
    
    For the early repayment of the silent partnership pursuant to § 1(2) of this Agreement the
notice period and the termination dates of § 10(2) of the Participation Agreements is
terminated. In this respect, only § 1(2) above shall apply.2.
    
    § 10(2) 4th indentation of the Participation Agreements shall apply accordingly
with regard to Micromet, Inc., Delaware, USA.3.
    
    Save as provided otherwise, the provisions of the Participation Agreements remain unaffected.
 §4
Condition Precedent
  (a)
    
    Consent of the Shareholders Meeting of Micromet AG to the present amendment
agreement as well as the application for and the registration of these amendments in
the Commercial Register;(b)
    
    Production of the guarantee declarations duly signed by Micromet, Inc. in
accordance with the forms attached as Annex Aand Annex B;(c)
    
    Contribution of more than 80% of the shares in Micromet AG to Micromet, Inc.
 §5
Consent
  §6
Final Provisions
 1.
    
    Changes and amendments to this Agreement require the written form. Oral side agreements to
this Agreement do not exist.2.
    
    In the event that a provision of this Agreement is invalid, the validity of the remaining
provisions shall not be affected thereby. The parties are under an obligation to replace
invalid provisions of this Agreement by such valid provisions, which correspond to the intent
and purpose of the invalid provisions to the closest possible extent.
 4.




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3.
    
    Place of jurisdiction for all disputes out of this Agreement or its performance shall be
Munich.4.
    
    The wording decisive for this Agreement shall be the wording in the German language.
 Landshut, 31 January 2006
    
    Munich, 31 January 2006/s/
    
    /s/(Bayern Kapital Risikokapitalbeteiligungs GmbH)
    
    (Technologie Beteilingungsfonds
Bayern GmbH & Co. KG)
  /s/ Christian Itin/s/ Gregor K. Mirow
  5.




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Exhibit 4.14
 Annex A
 [Letterhead of Micromet, Inc., Delaware, USA]




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Exhibit
4.14
 Annex B
 [Letterhead of Micromet, Inc., Delaware, USA]