SECOND AMENDMENT TO RIGHTS AGREEMENT

This Second Amendment to Rights Agreement (this “Amendment”) is entered into
effective as of February 25, 2008 (the “Effective Date”) by and between Adventrx
Pharmaceuticals, Inc., a Delaware corporation (the “Company”), and Icahn
Partners LP, Icahn Partners Master Fund LP and High River Limited Partnership
(collectively, the “Icahn Purchasers”).

WHEREAS, the Company, the Icahn Purchasers and Viking Global Equities LP and VGE
III Portfolio Ltd. (collectively, the “Viking Purchasers” and, together with the
Icahn Purchasers, the “Purchasers”) are parties to that certain Rights
Agreement, with an effective date of July 27, 2005, as amended (the “Rights
Agreement”), pursuant to which the Company agreed to set the authorized number
of directors constituting the Company’s board of directors at 6 and to not
change such number, except as set forth in the Rights Agreement;

WHEREAS, pursuant to Section 6.2 of the Rights Agreement, any term of the Rights
Agreement may be amended with the written consent of the Company and the Icahn
Purchasers;

NOW, THEREFORE, in consideration of both the foregoing premises and the terms
and conditions set forth below, the Company and the Icahn Purchasers hereby
agree as follows:

1. Board of Directors. The first sentence of Section 4 of the Rights Agreement
is hereby amended and restated to read in its entirety as follows:

“Effective promptly after the Closing, the Company shall set the authorized
number of Board directors at six and the Company shall appoint a person
suggested by the Purchasers which at the time own a majority of the Purchased
Shares (the “Purchaser Designee”) to the vacancy so created; provided, however,
that such person, if anyone other than Mr. Carl Icahn, would not subject the
Company to making any disclosures under Item 401(f) of SEC Regulation S-K in any
proxy statement (the “Criteria”); provided, further, that from time to time the
Board may increase the number of authorized Board directors to seven provided
that any vacancy created by such an increase is filled by a majority of the
Board directors then in office, which majority must include the Purchaser
Designee, if any; provided, further, that if at any time there are seven members
of the Board and one of such members is removed, resigns, retires or dies and
the Purchaser Designee, if any, does not approve a successor, the Company agrees
to do those things reasonably necessary and within its control to, as soon as
reasonably practicable after the effective date of such removal, resignation,
retirement or death, set the authorized number of Board directors at six.”

2. Purchaser Designee. The Company and the Purchasers agree that, as of the
Effective Date, the Purchaser Designee (as defined in the Rights Agreement) is
Alexander J. Denner.

3. Internal Reference. The Company and the Purchasers agree that any reference
in the Rights Agreement to “this Agreement” (or other similar reference) will be
a reference to the Rights Agreement, as amended.

4. Conflicts. Except to the extent amended herein, the Rights Agreement remains
in full force and effect.

5. Governing Law. This Amendment will be governed by and construed in accordance
with the laws of the State of New York applicable to agreements made and to be
fully performed therein.

[Signature page follows]

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IN WITNESS WHEREOF, the Company and the Icahn Purchasers have executed this
Second Amendment to Rights Agreement in duplicate originals effective as of the
Effective Date.

      COMPANY:   ADVENTRX PHARMACEUTICALS, INC.     By: /s/ Patrick L. Keran    
Name: Patrick L. Keran     Title: Vice President, Legal ICAHN PURCHASERS:  
ICAHN PARTNERS LP     By: /s/ [illegible]     (Authorized Signatory)
 
  ICAHN PARTNERS MASTER FUND LP
 
  By: /s/ [illegible]
 
   
 
  (Authorized Signatory)
 
  HIGH RIVER LIMITED PARTNERSHIP

By: Hooper Investments LLC, its general partner

By: Barbery Corp, its member

By: /s/ [illegible]

(Authorized Signatory)

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