Document:

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                                                                    EXHIBIT 4.27

THIS WARRANT HAS BEEN, AND THE SHARES OF COMMON STOCK WHICH MAY BE RECEIVED
PURSUANT TO THE EXERCISE OF THIS WARRANT WILL BE, ACQUIRED SOLELY FOR INVESTMENT
AND NOT WITH A VIEW TO, OR FOR RESALE IN CONNECTION WITH, ANY DISTRIBUTION
THEREOF. NEITHER THIS WARRANT NOR SUCH SHARES (TOGETHER, THE "SECURITIES") HAVE
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE,
PLEDGED OR HYPOTHECATED IN THE ABSENCE OF SUCH REGISTRATION OR AN OPINION OF
COUNSEL REASONABLY SATISFACTORY TO THE COMPANY THAT SUCH DISPOSITION IS EXEMPT
FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE ACT AND OF ANY
APPLICABLE STATE SECURITIES LAWS.

NO. [SEE ATTACHED SCHEDULE]                                ISSUED: APRIL 8, 2004

                      A-1 WARRANT TO PURCHASE COMMON STOCK

                                   ----------

     THIS CERTIFIES THAT, for good and valuable consideration, [SEE ATTACHED
SCHEDULE] (the "HOLDER") is entitled to purchase from ADVENTRX Pharmaceuticals,
Inc., a Delaware corporation (the "COMPANY"), [SEE ATTACHED SCHEDULE] fully paid
and nonassessable shares of Common Stock, par value $0.001 per share ("COMMON
STOCK"), of the Company (as adjusted pursuant to Section 3 hereof) (the "WARRANT
SHARES") at a price per share equal to Two Dollars ($2.00) (as adjusted pursuant
to Section 3 hereof) (the "EXERCISE PRICE"), subject to the provisions and upon
the terms and conditions hereinafter set forth.

1. METHOD OF EXERCISE; PAYMENT.

          (A) Exercise Period. The purchase right represented by this Warrant
     may be exercised in whole or part by the Holder during the term of this
     Warrant (as set forth in Section 9 hereof) at any time after the
     Commencement Date, as defined below, by the surrender of this Warrant (with
     the notice of exercise form attached hereto as Exhibit A (the "NOTICE OF
     EXERCISE") duly executed) at the principal office of the Company. If this
     Warrant shall have been exercised in part, the Company shall, at the time
     of delivery of the certificate or certificates representing Warrant Shares,
     deliver to the Holder a new Warrant evidencing the rights of the Holder to
     purchase the unpurchased shares of Common Stock called for by this Warrant,
     which new Warrant shall in all other respects be identical with this
     Warrant, or at the request of the Holder, appropriate notation may be made
     on this Warrant and the same returned to the Holder.

          (B) Exercise. Upon exercise of this Warrant, the Holder shall pay the
     Company an amount equal to the product of (x) the Exercise Price multiplied
     by (y) the total number of Warrant Shares purchased pursuant to this
     Warrant, by wire transfer or certified check payable to the order of the
     Company or, at any time following the first anniversary of the Warrant
     Date, if there is not an effective Registration Statement (as defined in
     the

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     Registration Rights Agreement) with respect to all of the Warrant Shares,
     then at the option of the Holder, such amount may be paid by the surrender
     of a portion of shares of Common Stock then held by the Holder or issuable
     upon such exercise of this Warrant, which shall be valued and credited
     toward such amount due to the Company for the exercise of the Warrant based
     upon the Current Market Price of the Common Stock. The person or persons in
     whose name(s) any certificate(s) representing the Warrant Shares shall be
     issuable upon exercise of this Warrant shall be deemed to have become the
     holder(s) of record of, and shall be treated for all purposes as the record
     holder(s) of, the Warrant Shares represented thereby (and such Warrant
     Shares shall be deemed to have been issued) immediately prior to the close
     of business on the date upon which this Warrant is exercised.

          "CURRENT MARKET PRICE" means, in respect of any share of Common Stock
     on any date herein specified,

          (1) if there shall not then be a public market for the Common Stock,
     the higher of

               (a) the book value per share of Common Stock at such date, and

               (b) the value per share of Common Stock at such date as
     determined in good faith by the Board,

          or

          (2) if there shall then be a public market for the Common Stock, the
     higher of (x) the book value per share of Common Stock at such date, and
     (y) the average of the daily market prices for the 10 consecutive trading
     days immediately before such date. The daily market price (the "DAILY
     MARKET PRICE") for each such trading day shall be (i) the closing price on
     such day on the principal stock exchange (including Nasdaq) on which such
     Common Stock is then listed or admitted to trading, or quoted, as
     applicable, (ii) if no sale takes place on such day on any such exchange,
     the last reported closing price on such day as officially quoted on any
     such exchange (including Nasdaq), (iii) if the Common Stock is not then
     listed or admitted to trading on any stock exchange, the last reported
     closing bid price on such day in the over-the-counter market, as furnished
     by the National Association of Securities Dealers Automatic Quotation
     System or the National Quotation Bureau, Inc., (iv) if neither such
     corporation at the time is engaged in the business of reporting such
     prices, as furnished by any similar firm then engaged in such business, or
     (v) if there is no such firm, as furnished by any member of the National
     Association of Securities Dealers, Inc. (the "NASD") selected mutually by
     the holder of this Warrant and the Company or, if they cannot agree upon
     such selection, as selected by two such members of the NASD, one of which
     shall be selected by holder of this Warrant and one of which shall be
     selected by the Company.

          (C) Stock Certificates. In the event of the exercise of this Warrant,
     certificates for the Warrant Shares so purchased shall be delivered to the
     Holder within a reasonable time after exercise, but in no case later than
     the date that is three business days following receipt by the Company of a
     Notice of Exercise duly completed and executed.

2. STOCK FULLY PAID; RESERVATION OF SHARES. All of the Warrant Shares issuable
upon the exercise of the rights represented by this Warrant will, upon issuance
and receipt of the Exercise

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Price therefor, be fully paid and nonassessable, and free from all preemptive
rights, rights of first refusal or first offer, taxes, liens and charges with
respect to the issuance thereof. During the period within which the rights
represented by this Warrant may be exercised, the Company shall at all times
have authorized and reserved for issuance a sufficient number of shares of its
Common Stock to provide for the exercise of the rights represented by this
Warrant.

3. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES. The number and kind of
Warrant Shares purchasable upon the exercise of this Warrant and the Exercise
Price therefor shall be subject to adjustment from time to time upon the
occurrence of certain events, as follows:

          (A) Reclassification, Consolidation or Reorganization. In case of any
     reclassification of the Common Stock (other than a change in par value, or
     as a result of a subdivision or combination), or in case of any
     consolidation or merger of the Company with or into another corporation
     (other than a Change of Control, as defined below) (any of which is a
     "REORGANIZATION TRANSACTION"), the Company, or such successor corporation
     as the case may be, shall execute a new warrant, providing that the Holder
     shall have the right to exercise such new warrant, and procure upon such
     exercise and payment of the same aggregate Exercise Price, in lieu of the
     Warrant Shares theretofore issuable upon exercise of this Warrant, the kind
     and amount of shares of stock, other securities, money and property as
     would be payable for the Warrant Shares issuable upon exercise of this
     Warrant as if such Warrant Shares were outstanding on the consummation of
     the Reorganization Transaction. For purposes of this Warrant, the term
     "CHANGE OF CONTROL" shall mean (i) any acquisition of the Company by means
     of merger, acquisition, or other form of corporate reorganization in which
     outstanding shares of the Company are exchanged for securities or other
     consideration issued, or caused to be issued, by the acquiring corporation
     or its subsidiary or parent (other than a reincorporation transaction or
     change of domicile) and pursuant to which the holders of the outstanding
     voting securities of the Company immediately prior to such consolidation,
     merger or other transaction fail to hold equity securities representing a
     majority of the voting power of the Company or surviving entity immediately
     following such consolidation, merger or other transaction (excluding voting
     securities of the acquiring corporation held by such holders prior to such
     transaction) or (ii) a sale of all or substantially all of the assets of
     the Company.

          (B) Stock Splits, Dividends and Combinations. In the event that the
     Company shall at any time subdivide the outstanding shares of Common Stock,
     or shall issue a stock dividend on its outstanding shares of Common Stock,
     the number of Warrant Shares issuable upon exercise of this Warrant
     immediately prior to such subdivision or to the issuance of such stock
     dividend shall be proportionately increased, and the Exercise Price shall
     be proportionately decreased, and in the event that the Company shall at
     any time combine the outstanding shares of Common Stock, the number of
     Warrant Shares issuable upon exercise of this Warrant immediately prior to
     such combination shall be proportionately decreased, and the Exercise Price
     shall be proportionately increased, effective at the close of business on
     the date of such subdivision, stock dividend or combination, as the case
     may be.

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          (C) Issuance of Additional Shares.

               (I) If at any time while this Warrant is outstanding and after
               June 30, 2004, the Company shall issue or sell any shares of its
               Common Stock (other than Excluded Shares (as that term is defined
               below), "ADDITIONAL SHARES") in exchange for consideration in an
               amount per Additional Share less than the Exercise Price at the
               time the Additional Shares are issued or sold, then the Exercise
               Price immediately prior to such issue or sale shall be reduced to
               a price determined by dividing:

                    (1) an amount equal to the sum of (a) the number of shares
                    of Common Stock outstanding immediately prior to such issue
                    or sale multiplied by the then existing Exercise Price, plus
                    (b) the consideration, if any, received by the Company upon
                    such issue or sale, by

                    (2) the total number of shares of Common Stock outstanding
                    immediately after such issue or sale.

               (II) The provisions of Section 3(c)(i) shall not apply to any
               deemed issuance of Additional Shares for which an adjustment is
               provided under Section 3(a) or 3(b). No adjustment of the number
               of shares of Common Stock acquirable upon exercise of this
               Warrant shall be made under Section 3(c) upon the issuance of any
               shares of Common Stock which are issued pursuant to the exercise
               of any warrants or other subscription or purchase rights or
               pursuant to the exercise of any conversion or exchange rights in
               any convertible securities, if any such adjustment shall
               previously have been made upon the issuance of such warrants or
               other rights or upon the issuance of such convertible securities
               (or upon the issuance of any warrant or other rights therefor)
               pursuant to Section 3(d).

     For purposes of this Warrant the term "EXCLUDED SHARES" means: (i) shares
     of Common Stock issuable or issued after the Closing Date to officers,
     employees, consultants or directors of the Company directly or pursuant to
     a stock purchase, stock option, restricted stock or other written
     compensation plan or agreement approved by the Board of Directors of the
     Company (the "BOARD"); (ii) shares of Common Stock issued or issuable after
     the Closing Date, primarily for non-equity financing purposes and as
     approved by the Board, to financial institutions or lessors in connection
     with commercial credit arrangements, equipment financings or similar
     transactions or to vendors of goods or services or customers; (iii) shares
     of Common Stock issuable upon (a) exercise of warrants, options, notes or
     other rights to acquire securities of the Company, in each case,
     outstanding on the issuance date of this Warrant (the "WARRANT Date"), (b)
     conversion of shares of the Company's Preferred Stock, par value $0.01 per
     share, outstanding on the Warrant Date, (c) exchange of promissory notes
     issued by the Company outstanding on the Warrant Date, (iv) the Shares (as
     such term is defined Common Stock and Warrant Purchase Agreement, dated as
     of the Warrant Date, among the Company and the persons and entities listed
     on Schedule 1 thereto (the "PURCHASE AGREEMENT")); (v) the Warrants (as
     such term is defined in the Purchase Agreement); (vi) capital stock or
     warrants or options to purchase capital stock issued in connection with
     bona fide acquisitions, mergers or similar transactions, the terms of which

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     are approved by the Board; (vii) shares of Common Stock issued or issuable
     to licensors of technology of the Company to pay expenses, royalties or
     milestone payments for which the Company is obligated under any licensing
     or related agreement; (viii) shares of Common Stock issuable or issued
     pursuant to stock splits, stock dividends and the like, or (ix) shares of
     Common Stock issued or issuable by way of dividend or other distribution on
     Excluded Shares.

          (D) Issuance of Common Stock Equivalents.

               (I) If at any time while this Warrant is outstanding the Company
               shall issue or sell any warrants or other rights to subscribe for
               or purchase any additional shares of Common Stock or any
               securities convertible into shares of Common Stock (other than
               the Additional Shares) (collectively, "COMMON STOCK
               EQUIVALENTS"), whether or not the rights to exchange or convert
               thereunder are immediately exercisable, and the effective price
               per share for which Common Stock is issuable upon the exercise,
               exchange or conversion of such Common Stock Equivalents shall be
               less than the Exercise Price in effect immediately prior to the
               time of such issue or sale, then the Exercise Price shall be
               adjusted as provided in Section 3(c) on the basis that the
               maximum number of additional shares of Common Stock issuable
               pursuant to all such Common Stock Equivalents shall be deemed to
               have been issued and outstanding and the Company shall have
               received all of the consideration payable therefor, if any, as of
               the date of the actual issuance of such Common Stock Equivalents.
               No further adjustments to the current Warrant Price shall be made
               under this Section 3(d) upon the actual issue of such Common
               Stock upon the exercise, conversion or exchange of such Common
               Stock Equivalents.

               (II) Upon the expiration or termination of any such Common Stock
               Equivalents, the Exercise Price, to the extent in any way
               affected by or computed using such Common Stock Equivalents,
               shall be recomputed to reflect the issuance of the total number
               of shares of Common Stock (and convertible or exchangeable
               securities which remain in effect) actually issued upon the
               exercise, exchange or conversion of such Common Stock Equivalents
               to the extent that this Warrant is then outstanding.

          (E) Other Action Affecting Common Stock. In case at any time or from
     time to time the Company shall take any action in respect of its Common
     Stock, other than the payment of dividends permitted by Section 3 or any
     other action described in Section 3, then, unless such action will not have
     a materially adverse effect upon the rights of the Holder, the number of
     shares of Common Stock or other stock into which this Warrant is
     exercisable and/or the purchase price thereof shall be adjusted in such
     manner as may be equitable in the circumstances.

          (F) Certificate as to Adjustments. Upon the occurrence of each
     adjustment or readjustment of the Exercise Price, the Company, at its
     expense, shall promptly compute such adjustment or readjustment in
     accordance with the terms hereof and prepare and furnish to the Holder of
     this Warrant a certificate setting forth such adjustment or readjustment
     and

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     showing in detail the facts upon which such adjustment or readjustment is
     based. The Company shall, upon the written request at any time of the
     Holder of this Warrant, furnish or cause to be furnished to such Holder a
     like certificate setting forth (i) such adjustments and readjustments, (ii)
     the Exercise Price at the time in effect and (iii) the number of shares of
     Common Stock and the amount, if any, or other property which at the time
     would be received upon the exercise of Warrants owned by such Holder.

          (G) Notice of Corporate Action. If at any time:

               (i) the Company shall take a record of the holders of its Common
     Stock for the purpose of entitling them to receive a dividend (other than a
     cash dividend payable out of earnings or earned surplus legally available
     for the payment of dividends under the laws of the jurisdiction of
     incorporation of the Company) or other distribution, or any right to
     subscribe for or purchase any evidences of its indebtedness, any shares of
     stock of any class or any other securities or property, or to receive any
     other right, or

               (ii) there shall be any capital reorganization of the Company,
     any reclassification or recapitalization of the capital stock of the
     Company or any consolidation or merger of the Company with, or any sale,
     transfer or other disposition of all or substantially all the property,
     assets or business of the Company to, another corporation, or

               (iii) there shall be a voluntary or involuntary dissolution,
     liquidation or winding up of the Company;

     then, in any one or more of such cases, the Company shall give to the
     Holder (i) at least 10-days' prior written notice of the date on which a
     record date shall be selected for such dividend, distribution or right or
     for determining rights to vote in respect of any such reorganization,
     reclassification, merger, consolidation, sale, transfer, disposition,
     dissolution, liquidation or winding up, and (ii) in the case of any such
     reorganization, reclassification, merger, consolidation, sale, transfer,
     disposition, dissolution, liquidation or winding up, at least 10-days'
     prior written notice of the date when the same shall take place. Such
     notice in accordance with the foregoing clause also shall specify (i) the
     date on which any such record is to be taken for the purpose of such
     dividend, distribution or right, the date on which the holders of Common
     Stock shall be entitled to any such dividend, distribution or right, and
     the amount and character thereof, and (ii) the date on which any such
     reorganization, reclassification, merger, consolidation, sale, transfer,
     disposition, dissolution, liquidation or winding up is to take place and
     the time, if any such time is to be fixed, as of which the holders of
     Common Stock shall be entitled to exchange their shares of Common Stock for
     securities or other property deliverable upon such reorganization,
     reclassification, merger, consolidation, sale, transfer, disposition,
     dissolution, liquidation or winding up. Each such written notice shall be
     sufficiently given if addressed to the Holder at the last address of the
     Holder appearing on the books of the Company and delivered in accordance
     with Section 11(d).

          (H) Adjustment if Registration Statement Not Effective. If a
     Registration Statement (as defined in the Registration Rights Agreement,
     dated as of the Warrant Date, among the Company and the persons and
     entities listed on Schedule 1 thereto (the "REGISTRATION RIGHTS

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     AGREEMENT")) is not effective with respect to all the Registrable
     Securities (as defined in the Registration Rights Agreement), other than
     Regisrtable Securities held by holders (i) which have not complied with the
     Registration Rights Agreement, including, without limitation, Section 4
     thereof, or (ii) have otherwise not permitted the Company to include such
     Registrable Securities on the Registration Statement, on or prior to
     November 12, 2004, then the Exercise Price shall be adjusted to equal $1.50
     (subject to adjustment for stock splits, reverse splits, stock dividends
     and the like, and subject to adjustment in proportion to any adjustment
     pursuant to Section 3(c)).

4. TRANSFER OF WARRANT. This Warrant may only be transferred in compliance with
federal and state securities laws; provided, however, that the Company may
withhold its consent to transfer or assignment of this Warrant to any person or
entity who is deemed to be a competitor or prospective competitor of the
Company, such determination to be made in the reasonable judgment of the Board.
If, at the time of the surrender of this Warrant in connection with any transfer
of this Warrant or the resale of the Warrant Stock, this Warrant or the Warrant
Stock, as applicable, shall not be registered under the Securities Act, the
Company may require, as a condition of allowing such transfer (i) that the
Holder or transferee of this Warrant or the Warrant Stock as the case may be,
furnish to the Company a written opinion of counsel that is reasonably
acceptable to the Company to the effect that such transfer may be made without
registration under the Securities Act, (ii) that the Holder or transferee
execute and deliver to the Company an investment letter in form and substance
acceptable to the Company and substantially in the form attached as Exhibit B
hereto and (iii) that the transferee be an "accredited investor" as defined in
Rule 501(a) promulgated under the Securities Act. Transfer of this Warrant and
all rights hereunder, in whole or in part, in accordance with the foregoing
provisions, shall be registered on the books of the Company to be maintained for
such purpose, upon surrender of this Warrant at the principal office of the
Company or the office or agency designated by the Company, together with a
written assignment of this Warrant substantially in the form of Exhibit C hereto
duly executed by the Holder or its attorney-in-fact and funds sufficient to pay
any transfer taxes payable upon the making of such transfer. Upon such surrender
and, if required, such payment, the Company shall execute and deliver a new
Warrant or Warrants in the name of the assignee or assignees and in the
denomination specified in such instrument of assignment, and shall issue to the
assignor a new Warrant evidencing the portion of this Warrant not so assigned,
and this Warrant shall promptly be cancelled. Following a transfer that complies
with the requirements of this Section 4, the Warrant may be exercised by a new
Holder for the purchase of shares of Common Stock regardless of whether the
Company issued or registered a new Warrant on the books of the Company. This
Section 4 shall survive the exercise or expiration of the Warrant.

5. CONDITIONS TO EXERCISE OF WARRANT.

          (A) Each certificate evidencing the Warrant Shares issued upon
     exercise of this Warrant shall be stamped or imprinted with a legend
     substantially in the following form:

          THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
          SECURITIES ACT OF 1933 (THE "ACT") AND MAY NOT BE OFFERED, SOLD OR
          OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL
          REGISTERED

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          UNDER THE ACT OR, IN THE OPINION OF COUNSEL IN FORM AND SUBSTANCE
          SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR
          TRANSFER, PLEDGE OR HYPOTHECATION IS IN COMPLIANCE THEREWITH.

          (B) REMOVAL OF LEGEND AND TRANSFER RESTRICTIONS. Any legend endorsed
     on a certificate pursuant to this Section 5 shall be removed, and the
     Company shall issue a certificate without such legend to the holder of such
     Warrant Shares if (i) such Warrant Shares are resold pursuant to a
     registration statement under the Securities Act of 1933, as amended, and a
     prospectus meeting the requirements of Section 10 of the Securities Act is
     delivered or deemed delivered to the purchaser of such Warrant Shares, (ii)
     if such holder satisfies the requirements of Rule 144(k) or (iii) if such
     holder provides the Company with an opinion of counsel for such holder of
     the Warrant Shares, reasonably satisfactory to the Company, to the effect
     that a sale, transfer or assignment of such Warrant Shares may be made
     without registration. This paragraph shall survive any exercise of this
     Warrant.

          (C) RESTRICTIONS ON EXERCISE AMOUNT. Unless a Holder delivers to the
     Company irrevocable written notice (x) prior to the date of issuance hereof
     or 61 days prior to the effective date of such notice that this Section
     5(c) shall not apply to such Holder or (y) prior to a Change of Control,
     the Holder may not acquire a number of Warrant Shares to the extent that,
     upon such exercise, the number of shares of Common Stock then beneficially
     owned by such Holder and its affiliates and any other persons or entities
     whose beneficial ownership of Common Stock would be aggregated with the
     Holder's for purposes of Section 13(d) of the Securities Exchange Act of
     1934, as amended (the "EXCHANGE ACT"), (including shares held by any
     "group" of which the Holder is a member, but excluding shares beneficially
     owned by virtue of the ownership of securities or rights to acquire
     securities that have limitations on the right to convert, exercise or
     purchase similar to the limitation set forth herein) exceeds 9.99% of the
     total number of shares of Common Stock of the Company then issued and
     outstanding. For purposes hereof, "group" has the meaning set forth in
     Section 13(d) of the Exchange Act and applicable regulations of the
     Securities Exchange Commission (the "COMMISSION"), and the percentage held
     by the holder shall be determined in a manner consistent with the
     provisions of Section 13(d) of the Exchange Act. Each delivery of a notice
     of exercise by a Holder will constitute a representation by such Holder
     that it has evaluated the limitation set forth in this paragraph and
     determined, based on the most recent public filings by the Company with the
     Commission, that the issuance of the full number of Warrant Shares
     requested in such notice of exercise is permitted under this paragraph.

6. FRACTIONAL SHARES. No fractional Warrant Shares will be issued in connection
with any exercise hereunder, but in lieu of such fractional shares the Company
shall make a cash payment therefor upon the basis of the Exercise Price then in
effect.

7. REGISTRATION RIGHTS. The Holder shall have the registration rights described
in the Registration Rights Agreement.

8. RIGHTS OF STOCKHOLDERS. No Holder shall be entitled, as a Warrant holder, to
vote or receive dividends or be deemed the holder of Warrant Shares or any other
securities of the Company which may at any time be issuable on the exercise
hereof for any purpose, nor shall

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anything contained herein be construed to confer upon the Holder any of the
rights of a stockholder of the Company or any right to vote for the election of
directors or upon any matter submitted to stockholders at any meeting thereof,
or to give or withhold consent to any corporate action (whether upon any
recapitalization, issuance of stock, reclassification of stock, change of par
value, consolidation, merger, conveyance, or otherwise) or to receive dividends
or subscription rights or otherwise with respect to the Warrant Shares until
this Warrant shall have been exercised and the Warrant Shares purchasable upon
the exercise hereof shall have become deliverable, as provided herein.

9. TERM OF WARRANT. This Warrant shall become exercisable on the Warrant Date
and shall no longer be exercisable as of the earlier of (i) 5:00 p.m., San
Diego, California local time, on the date that is the five-year anniversary of
the Warrant Date; and (ii) upon consummation of a Change of Control.

10. REDEMPTION AT COMPANY'S ELECTION. The Company may at the option of the
Board, by at least seven-days' prior written notice to the Holder (the
"REDEMPTION NOTICE"), redeem this Warrant, in whole or in part, at any time
after June 30, 2004, provided that (i) the Daily Market Price for twenty
consecutive trading days is equal to or greater than the product of (x) 2
multiplied by (y) the Exercise Price, (ii) either (A) all of the Warrant Shares
underlying this Warrant to be redeemed are then registered under an effective
registration statement or (B) may be sold pursuant to Rule 144 during a
three-month period without registration under the Securities Act, (iii)
sufficient shares of Common Stock of the Company are authorized and reserved for
issuance upon the full exercise of this Warrant, (iv) all of the Warrant Shares
issuable upon exercise of this Warrant are then listed on every stock exchange,
market or bulletin board on which any Common Stock of the Company is then listed
and (v) the Company is not in default of any material provision of any
Transaction Agreement (as defined in the Purchase Agreement). The Redemption
Notice shall set forth a date, not less than seven days after the date of the
Redemption Notice, on which the redemption of this Warrant shall occur (the
"REDEMPTION DATE"). On the Redemption Date, (i) the Company shall pay the Holder
by certified check an amount equal to the product of (x) $0.01 (as adjusted in
proportion to any adjustment to the Exercise Price pursuant to Section 3 hereof)
multiplied by (y) the number of Warrant Shares so redeemed; and (ii) the Holder
shall deliver the original copy of this Warrant marked "REDEEMED" to the
Company. If the Company shall redeem this Warrant in part, the Company shall, at
the Redemption Date, provided that the Holder shall have delivered the original
copy of this Warrant marked "REDEEMED" to the Company, deliver to the Holder a
new Warrant evidencing the rights of the Holder to purchase the unredeemed
shares of Common Stock called for by this Warrant, which new Warrant shall in
all other respects be identical with this Warrant. Nothing in this Section 10
shall prevent the exercise of the Warrants at any time prior to the Redemption
Date.

11. MISCELLANEOUS.

          (A) This Warrant is being delivered in the State of California and
     shall be construed and enforced in accordance with and governed by the laws
     of the State of California, without giving effect to principles of
     conflicts of laws.

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          (B) The headings in this Warrant are for purposes of reference only,
     and shall not limit or otherwise affect any of the terms hereof.

          (C) The terms of this Warrant shall be binding upon and shall inure to
     the benefit of any successors or assigns of the Company and of the Holder
     and of the Warrant Shares issued or issuable upon the exercise hereof.

          (D) Any notice provided for or permitted under this Warrant shall be
     treated as having been given (a) upon receipt, when delivered personally or
     sent by confirmed facsimile or telecopy, (b) one day after sending, when
     sent by commercial overnight courier with written verification of receipt,
     or (c) three business days after deposit with the United States Postal
     Service, when mailed postage prepaid by certified or registered mail,
     return receipt requested, addressed (a) if to the Company, at 9948 Hibert
     Street, Suite 100, San Diego, CA 92131, facsimile: (858) 271-9678,
     Attention: Nicholas J. Virca, or, if to the Holder, at such address or
     facsimile number as the Holder shall have furnished to the Company in
     writing, or at such other place of which the other party has been notified
     in accordance with the provisions of this Section 11(d).

          (E) This Warrant constitutes the full and entire understanding and
     agreement between the parties with regard to the subjects hereof.

          (F) Upon receipt of evidence reasonably satisfactory to the Company of
     the loss, theft, destruction or mutilation of this Warrant and, in the case
     of any such loss, theft or destruction, upon delivery of an indemnity
     agreement reasonably satisfactory in form and amount to the Company or, in
     the case of any such mutilation, upon surrender and cancellation of such
     Warrant, the Company at the Holder's expense will execute and deliver to
     the holder of record, in lieu thereof, a new Warrant of like date and
     tenor.

          (G) This Warrant and any provision hereof may be amended, waived or
     terminated only by an instrument in writing signed by the Company and the
     Holder.

          (H) Receipt of this Warrant by the Holder shall constitute acceptance
     of and agreement to the foregoing terms and conditions.

                            [Signature page follows.]

                                      -10-

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
duly authorized officer.

Issued: April 8, 2004

                                        ADVENTRX PHARMACEUTICALS, INC.

                                        By: /s/ Nicholas J. Virca
                                            ------------------------------------
                                            Nicholas J. Virca
                                            President & CEO

           SIGNATURE PAGE TO THE A-1 WARRANT TO PURCHASE COMMON STOCK

<PAGE>

                                    EXHIBIT A

                               NOTICE OF EXERCISE

TO: ADVENTRX Pharmaceuticals, Inc.
    9948 Hibert Street, Suite 100
    San Diego, CA 92131

     1. The undersigned hereby elects to purchase ____________ shares of Common
Stock, par value $0.001 per share, of the Company ("COMMON STOCK") pursuant to
the terms of Section 1(b) of the A-1 Warrant to Purchase Common Stock dated
___________ 2004 (the "WARRANT"), and tenders herewith payment of the purchase
price of such shares in full.

     2. The undersigned hereby elects to convert the attached Warrant into
Common Stock of Adventrx Pharmaceuticals, Inc. through "cashless exercise" in
the manner specified in the Warrant. This conversion is exercised with respect
to _____________________ of the Shares covered by the Warrant.

     Please issue a certificate or certificates representing said _________
shares of Common Stock in the name of the undersigned or in such other name as
is specified below:

                                        Name:
                                              ----------------------------------
                                        Address:
                                                 -------------------------------

                                                 -------------------------------

     The undersigned hereby represents and warrants that the aforesaid shares of
Common Stock are being acquired for the account of the undersigned for
investment and not with a view to, or for resale, in connection with the
distribution thereof, and that the undersigned has no present intention of
distributing or reselling such shares, and that all representations and
warranties of the undersigned with respect to the Warrant and Warrant Shares (as
defined in the Warrant) set forth in Section 4 of the Purchase Agreement (as
defined in the Warrant) were true and correct as of the Warrant Date (as defined
in the Warrant) and are true and correct as of the date hereof.

                                        ----------------------------------------

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------
                                        Date:
                                               ---------------------------------

<PAGE>

                                    EXHIBIT B

                    FORM OF INVESTMENT REPRESENTATION LETTER

In connection with the acquisition of [warrants (the "Warrants") to purchase
_______ shares of Common Stock of ADVENTRX Pharmaceuticals, Inc. (the
"Company"), par value $0.001 per share (the "Common Stock")][________ shares of
Common Stock of ADVENTRX Pharmaceuticals, Inc. (the "Company"), par value $0.001
per share (the "Common Stock")], by _______________ (the "Holder") from
_____________, the Holder hereby represents and warrants to the Company as
follows:

The Holder (i) is an "Accredited Investor" as that term is defined in Rule 501
of Regulation D promulgated under the Securities Act of 1933, as amended (the
"Act"); and (ii) has the ability to bear the economic risks of such Holder's
prospective investment, including a complete loss of Holder's investment in the
Warrants and the shares of Common Stock issuable upon the exercise thereof
(collectively, the "Securities").

The Holder, by acceptance of the Warrants, represents and warrants to the
Company that the Warrants and all securities acquired upon any and all exercises
of the Warrants are purchased for the Holder's own account, and not with view to
distribution of either the Warrants or any securities purchasable upon exercise
thereof in violation of applicable securities laws.

The Holder acknowledges that (i) the Securities have not been registered under
the Act, (ii) the Securities are "restricted securities" and the certificate(s)
representing the Securities shall bear the following legend, or a similar legend
to the same effect, until (i) in the case of the shares of Common Stock
underlying the Warrants, such shares shall have been registered for resale by
the Holder under the Act and effectively been disposed of in accordance with a
registration statement that has been declared effective; or (ii) in the opinion
of counsel for the Company such Securities may be sold without registration
under the Act:

"[NEITHER] THE SECURITIES REPRESENTED BY THIS CERTIFICATE [NOR THE SECURITIES
INTO WHICH THEY ARE EXERCISABLE] HAVE [NOT] BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), AND ALL SUCH SECURITIES ARE SUBJECT TO
RESTRICTIONS ON TRANSFERABILITY AS SET FORTH IN THIS CERTIFICATE. [NEITHER] THE
SECURITIES REPRESENTED HEREBY [NOR THE SECURITIES INTO WHICH THEY ARE
EXERCISABLE] MAY [NOT] BE SOLD, TRANSFERRED, OR OTHERWISE DISPOSED OF IN THE
ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT OR AN OPINION OF
COUNSEL, REASONABLY ACCEPTABLE TO COUNSEL FOR THE COMPANY, TO THE EFFECT THAT
THE PROPOSED SALE, TRANSFER, OR DISPOSITION MAY BE EFFECTUATED WITHOUT
REGISTRATION UNDER THE ACT."

IN WITNESS WHEREOF, the Holder has caused this Investment Representation Letter
to be executed in its corporate name by its duly authorized officer this __ day
of __________ 200_.

[Name]

By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------

<PAGE>

                                    EXHIBIT C

                                 ASSIGNMENT FORM

FOR VALUE RECEIVED the undersigned registered owner of this Warrant for the
purchase of shares of Common Stock of ADVENTRX Pharmaceuticals, Inc. hereby
sells, assigns and transfers unto the Assignee named below all of the rights of
the undersigned under this Warrant, with respect to the number of shares of
common stock set forth below:

-------------------------------------

-------------------------------------

-------------------------------------
(Name and Address of Assignee)

-------------------------------------
(Number of Shares of Common Stock)

and does hereby irrevocably constitute and appoint ____________ attorney-in-fact
to register such transfer on the books of the Company, maintained for the
purpose, with full power of substitution in the premises.

Dated:
       ------------------------------

-------------------------------------
(Print Name and Title)

-------------------------------------
(Signature)

-------------------------------------
(Witness)

NOTICE: The signature on this assignment must correspond with the name as
written upon the face of the Warrant in every particular, without alteration or
enlargement or any change whatsoever.

<PAGE>

                           SCHEDULE OF WARRANTHOLDERS

     ADVENTRX Pharmaceuticals, Inc. issued this form of A-1 Warrant to Purchase
Common Stock to each of the persons listed below for the purchase of up to the
number of shares of Common Stock listed opposite such person's name below.

<TABLE>
<CAPTION>
HOLDER                                                   WARRANT NO.   SHARES
------                                                   -----------   ------
<S>                                                      <C>           <C>
Andrew J. Maffey                                            WA1-86      5,100
Centrum Bank AG                                             WA1-57      9,000
North Sound Legacy Institutional Fund LLC                   WA1-92      3,600
North Sound Legacy Institutional Fund LLC                   WA1-85     18,600
North Sound Legacy International Ltd                        WA1-83     40,200
Legend Merchant Group, Inc.                                 WA1-67      1,500
Robert J. Neborsky MD Inc Combination Retirement Trust      WA1-89     49,500
Robert J. Neborsky MD Inc Combination Retirement Trust      WA1-90     49,500
North Sound Legacy Institutional Fund LLC                   WA1-93      1,200
</TABLE><PAGE>
                                                                    EXHIBIT 4.28

THIS WARRANT HAS BEEN, AND THE SHARES OF COMMON STOCK WHICH MAY BE RECEIVED
PURSUANT TO THE EXERCISE OF THIS WARRANT WILL BE, ACQUIRED SOLELY FOR INVESTMENT
AND NOT WITH A VIEW TO, OR FOR RESALE IN CONNECTION WITH, ANY DISTRIBUTION
THEREOF. NEITHER THIS WARRANT NOR SUCH SHARES (TOGETHER, THE "SECURITIES") HAVE
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD, OFFERED FOR SALE,
PLEDGED OR HYPOTHECATED IN THE ABSENCE OF SUCH REGISTRATION OR AN OPINION OF
COUNSEL REASONABLY SATISFACTORY TO THE COMPANY THAT SUCH DISPOSITION IS EXEMPT
FROM THE REGISTRATION AND PROSPECTUS DELIVERY REQUIREMENTS OF THE ACT AND OF ANY
APPLICABLE STATE SECURITIES LAWS.

NO. [SEE ATTACHED SCHEDULE]                                ISSUED: APRIL 8, 2004

                      A-2 WARRANT TO PURCHASE COMMON STOCK

                                   ----------

     THIS CERTIFIES THAT, for good and valuable consideration, [SEE ATTACHED
SCHEDULE] (the "HOLDER") is entitled to purchase from ADVENTRX Pharmaceuticals,
Inc., a Delaware corporation (the "COMPANY"), [SEE ATTACHED SCHEDULE] fully paid
and nonassessable shares of Common Stock, par value $0.001 per share ("COMMON
STOCK"), of the Company (as adjusted pursuant to Section 3 hereof) (the "WARRANT
SHARES") at a price per share equal to Two Dollars and Fifty Cents ($2.50) (as
adjusted pursuant to Section 3 hereof) (the "EXERCISE PRICE"), subject to the
provisions and upon the terms and conditions hereinafter set forth.

1. METHOD OF EXERCISE; PAYMENT.

          (A) Exercise Period. The purchase right represented by this Warrant
     may be exercised in whole or part by the Holder during the term of this
     Warrant (as set forth in Section 9 hereof) at any time after the
     Commencement Date, as defined below, by the surrender of this Warrant (with
     the notice of exercise form attached hereto as Exhibit A (the "NOTICE OF
     EXERCISE") duly executed) at the principal office of the Company. If this
     Warrant shall have been exercised in part, the Company shall, at the time
     of delivery of the certificate or certificates representing Warrant Shares,
     deliver to the Holder a new Warrant evidencing the rights of the Holder to
     purchase the unpurchased shares of Common Stock called for by this Warrant,
     which new Warrant shall in all other respects be identical with this
     Warrant, or at the request of the Holder, appropriate notation may be made
     on this Warrant and the same returned to the Holder.

          (B) Exercise. Upon exercise of this Warrant, the Holder shall pay the
     Company an amount equal to the product of (x) the Exercise Price multiplied
     by (y) the total number of Warrant Shares purchased pursuant to this
     Warrant, by wire transfer or certified check payable to the order of the
     Company or, at any time following the first anniversary of the Warrant
     Date, if there is not an effective Registration Statement (as defined in
     the

<PAGE>

     Registration Rights Agreement, dated as of the Warrant Date, among the
     Company and the persons and entities listed on Schedule 1 thereto (the
     "REGISTRATION RIGHTS AGREEMENT") with respect to all of the Warrant Shares,
     then at the option of the Holder, such amount may be paid by the surrender
     of a portion of shares of Common Stock then held by the Holder or issuable
     upon such exercise of this Warrant, which shall be valued and credited
     toward such amount due to the Company for the exercise of the Warrant based
     upon the Current Market Price of the Common Stock. The person or persons in
     whose name(s) any certificate(s) representing the Warrant Shares shall be
     issuable upon exercise of this Warrant shall be deemed to have become the
     holder(s) of record of, and shall be treated for all purposes as the record
     holder(s) of, the Warrant Shares represented thereby (and such Warrant
     Shares shall be deemed to have been issued) immediately prior to the close
     of business on the date upon which this Warrant is exercised.

          "CURRENT MARKET PRICE" means, in respect of any share of Common Stock
     on any date herein specified,

          (1) if there shall not then be a public market for the Common Stock,
     the higher of

               (a) the book value per share of Common Stock at such date, and

               (b) the value per share of Common Stock at such date as
     determined in good faith by the Board,

          or

          (2) if there shall then be a public market for the Common Stock, the
     higher of (x) the book value per share of Common Stock at such date, and
     (y) the average of the daily market prices for the 10 consecutive trading
     days immediately before such date. The daily market price (the "DAILY
     MARKET PRICE") for each such trading day shall be (i) the closing price on
     such day on the principal stock exchange (including Nasdaq) on which such
     Common Stock is then listed or admitted to trading, or quoted, as
     applicable, (ii) if no sale takes place on such day on any such exchange,
     the last reported closing price on such day as officially quoted on any
     such exchange (including Nasdaq), (iii) if the Common Stock is not then
     listed or admitted to trading on any stock exchange, the last reported
     closing bid price on such day in the over-the-counter market, as furnished
     by the National Association of Securities Dealers Automatic Quotation
     System or the National Quotation Bureau, Inc., (iv) if neither such
     corporation at the time is engaged in the business of reporting such
     prices, as furnished by any similar firm then engaged in such business, or
     (v) if there is no such firm, as furnished by any member of the National
     Association of Securities Dealers, Inc. (the "NASD") selected mutually by
     the holder of this Warrant and the Company or, if they cannot agree upon
     such selection, as selected by two such members of the NASD, one of which
     shall be selected by holder of this Warrant and one of which shall be
     selected by the Company.

          (C) Stock Certificates. In the event of the exercise of this Warrant,
     certificates for the Warrant Shares so purchased shall be delivered to the
     Holder within a reasonable time after

                                       -2-

<PAGE>

     exercise, but in no case later than the date that is three business days
     following receipt by the Company of a Notice of Exercise duly completed and
     executed.

2. STOCK FULLY PAID; RESERVATION OF SHARES. All of the Warrant Shares issuable
upon the exercise of the rights represented by this Warrant will, upon issuance
and receipt of the Exercise Price therefor, be fully paid and nonassessable, and
free from all preemptive rights, rights of first refusal or first offer, taxes,
liens and charges with respect to the issuance thereof. During the period within
which the rights represented by this Warrant may be exercised, the Company shall
at all times have authorized and reserved for issuance a sufficient number of
shares of its Common Stock to provide for the exercise of the rights represented
by this Warrant.

3. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES. The number and kind of
Warrant Shares purchasable upon the exercise of this Warrant and the Exercise
Price therefor shall be subject to adjustment from time to time upon the
occurrence of certain events, as follows:

          (A) Reclassification, Consolidation or Reorganization. In case of any
     reclassification of the Common Stock (other than a change in par value, or
     as a result of a subdivision or combination), or in case of any
     consolidation or merger of the Company with or into another corporation
     (other than a Change of Control, as defined below) (any of which is a
     "REORGANIZATION TRANSACTION"), the Company, or such successor corporation
     as the case may be, shall execute a new warrant, providing that the Holder
     shall have the right to exercise such new warrant, and procure upon such
     exercise and payment of the same aggregate Exercise Price, in lieu of the
     Warrant Shares theretofore issuable upon exercise of this Warrant, the kind
     and amount of shares of stock, other securities, money and property as
     would be payable for the Warrant Shares issuable upon exercise of this
     Warrant as if such Warrant Shares were outstanding on the consummation of
     the Reorganization Transaction. For purposes of this Warrant, the term
     "CHANGE OF CONTROL" shall mean (i) any acquisition of the Company by means
     of merger, acquisition, or other form of corporate reorganization in which
     outstanding shares of the Company are exchanged for securities or other
     consideration issued, or caused to be issued, by the acquiring corporation
     or its subsidiary or parent (other than a reincorporation transaction or
     change of domicile) and pursuant to which the holders of the outstanding
     voting securities of the Company immediately prior to such consolidation,
     merger or other transaction fail to hold equity securities representing a
     majority of the voting power of the Company or surviving entity immediately
     following such consolidation, merger or other transaction (excluding voting
     securities of the acquiring corporation held by such holders prior to such
     transaction) or (ii) a sale of all or substantially all of the assets of
     the Company.

          (B) Stock Splits, Dividends and Combinations. In the event that the
     Company shall at any time subdivide the outstanding shares of Common Stock,
     or shall issue a stock dividend on its outstanding shares of Common Stock,
     the number of Warrant Shares issuable upon exercise of this Warrant
     immediately prior to such subdivision or to the issuance of such stock
     dividend shall be proportionately increased, and the Exercise Price shall
     be proportionately decreased, and in the event that the Company shall at
     any time combine the outstanding shares of Common Stock, the number of
     Warrant Shares issuable upon exercise of this Warrant immediately prior to
     such combination shall be proportionately decreased,

                                       -3-

<PAGE>

     and the Exercise Price shall be proportionately increased, effective at the
     close of business on the date of such subdivision, stock dividend or
     combination, as the case may be.

          (C) Issuance of Additional Shares.

               (I) If at any time while this Warrant is outstanding and after
               June 30, 2004, the Company shall issue or sell any shares of its
               Common Stock, other than Excluded Shares (as that term is defined
               below) ("ADDITIONAL SHARES"), in exchange for consideration in an
               amount per Additional Share less than the Exercise Price at the
               time the Additional Shares are issued or sold, then the Exercise
               Price immediately prior to such issue or sale shall be reduced to
               a price determined by dividing:

                    (1) an amount equal to the sum of (a) the number of shares
                    of Common Stock outstanding immediately prior to such issue
                    or sale multiplied by the then existing Exercise Price, plus
                    (b) the consideration, if any, received by the Company upon
                    such issue or sale, by

                    (2) the total number of shares of Common Stock outstanding
                    immediately after such issue or sale.

               (II) The provisions of Section 3(c)(i) shall not apply to any
               deemed issuance of Additional Shares for which an adjustment is
               provided under Section 3(a) or 3(b). No adjustment of the number
               of shares of Common Stock acquirable upon exercise of this
               Warrant shall be made under Section 3(c) upon the issuance of any
               shares of Common Stock which are issued pursuant to the exercise
               of any warrants or other subscription or purchase rights or
               pursuant to the exercise of any conversion or exchange rights in
               any convertible securities, if any such adjustment shall
               previously have been made upon the issuance of such warrants or
               other rights or upon the issuance of such convertible securities
               (or upon the issuance of any warrant or other rights therefor)
               pursuant to Section 3(d).

     For purposes of this Warrant the term "EXCLUDED SHARES" means: (i) shares
     of Common Stock issuable or issued after the Closing Date to officers,
     employees, consultants or directors of the Company directly or pursuant to
     a stock purchase, stock option, restricted stock or other written
     compensation plan or agreement approved by the Board of Directors of the
     Company (the "BOARD"); (ii) shares of Common Stock issued or issuable after
     the Closing Date, primarily for non-equity financing purposes and as
     approved by the Board, to financial institutions or lessors in connection
     with commercial credit arrangements, equipment financings or similar
     transactions or to vendors of goods or services or customers; (iii) shares
     of Common Stock issuable upon (a) exercise of warrants, options, notes or
     other rights to acquire securities of the Company, in each case,
     outstanding on the issuance date of this Warrant (the "WARRANT DATE"), (b)
     conversion of shares of the Company's Preferred Stock, par value $0.01 per
     share, outstanding on the Warrant Date, (c) exchange of promissory notes
     issued by the Company outstanding on the Warrant Date, (iv) the Shares (as
     such term is defined in the Common Stock and Warrant Purchase Agreement,
     dated as of the Warrant Date, among the Company and the persons and
     entities listed on Schedule 1

                                       -4-

<PAGE>

     thereto (the "PURCHASE AGREEMENT")); (v) the Warrants (as such term is
     defined in the Purchase Agreement); (vi) capital stock or warrants or
     options to purchase capital stock issued in connection with bona fide
     acquisitions, mergers or similar transactions, the terms of which are
     approved by the Board; (vii) shares of Common Stock issued or issuable to
     licensors of technology of the Company to pay expenses, royalties or
     milestone payments for which the Company is obligated under any licensing
     or related agreement; (viii) shares of Common Stock issuable or issued
     pursuant to stock splits, stock dividends and the like, or (ix) shares of
     Common Stock issued or issuable by way of dividend or other distribution on
     Excluded Shares.

          (D) Issuance of Common Stock Equivalents.

               (I) If at any time while this Warrant is outstanding the Company
               shall issue or sell any warrants or other rights to subscribe for
               or purchase any additional shares of Common Stock or any
               securities convertible into shares of Common Stock (other than
               the Additional Shares) (collectively, "COMMON STOCK
               EQUIVALENTS"), whether or not the rights to exchange or convert
               thereunder are immediately exercisable, and the effective price
               per share for which Common Stock is issuable upon the exercise,
               exchange or conversion of such Common Stock Equivalents shall be
               less than the Exercise Price in effect immediately prior to the
               time of such issue or sale, then the Exercise Price shall be
               adjusted as provided in Section 3(c) on the basis that the
               maximum number of additional shares of Common Stock issuable
               pursuant to all such Common Stock Equivalents shall be deemed to
               have been issued and outstanding and the Company shall have
               received all of the consideration payable therefor, if any, as of
               the date of the actual issuance of such Common Stock Equivalents.
               No further adjustments to the current Warrant Price shall be made
               under this Section 3(d) upon the actual issue of such Common
               Stock upon the exercise, conversion or exchange of such Common
               Stock Equivalents.

               (II) Upon the expiration or termination of any such Common Stock
               Equivalents, the Exercise Price, to the extent in any way
               affected by or computed using such Common Stock Equivalents,
               shall be recomputed to reflect the issuance of the total number
               of shares of Common Stock (and convertible or exchangeable
               securities which remain in effect) actually issued upon the
               exercise, exchange or conversion of such Common Stock Equivalents
               to the extent that this Warrant is then outstanding.

          (E) Other Action Affecting Common Stock. In case at any time or from
     time to time the Company shall take any action in respect of its Common
     Stock, other than the payment of dividends permitted by Section 3 or any
     other action described in Section 3, then, unless such action will not have
     a materially adverse effect upon the rights of the Holder, the number of
     shares of Common Stock or other stock into which this Warrant is
     exercisable and/or the purchase price thereof shall be adjusted in such
     manner as may be equitable in the circumstances.

                                       -5-

<PAGE>

          (F) Certificate as to Adjustments. Upon the occurrence of each
     adjustment or readjustment of the Exercise Price, the Company, at its
     expense, shall promptly compute such adjustment or readjustment in
     accordance with the terms hereof and prepare and furnish to the Holder of
     this Warrant a certificate setting forth such adjustment or readjustment
     and showing in detail the facts upon which such adjustment or readjustment
     is based. The Company shall, upon the written request at any time of the
     Holder of this Warrant, furnish or cause to be furnished to such Holder a
     like certificate setting forth (i) such adjustments and readjustments, (ii)
     the Exercise Price at the time in effect and (iii) the number of shares of
     Common Stock and the amount, if any, or other property which at the time
     would be received upon the exercise of Warrants owned by such Holder.

          (G) Notice of Corporate Action. If at any time:

               (i) the Company shall take a record of the holders of its Common
     Stock for the purpose of entitling them to receive a dividend (other than a
     cash dividend payable out of earnings or earned surplus legally available
     for the payment of dividends under the laws of the jurisdiction of
     incorporation of the Company) or other distribution, or any right to
     subscribe for or purchase any evidences of its indebtedness, any shares of
     stock of any class or any other securities or property, or to receive any
     other right, or

               (ii) there shall be any capital reorganization of the Company,
     any reclassification or recapitalization of the capital stock of the
     Company or any consolidation or merger of the Company with, or any sale,
     transfer or other disposition of all or substantially all the property,
     assets or business of the Company to, another corporation, or

               (iii) there shall be a voluntary or involuntary dissolution,
     liquidation or winding up of the Company;

     then, in any one or more of such cases, the Company shall give to the
     Holder (i) at least 10-days' prior written notice of the date on which a
     record date shall be selected for such dividend, distribution or right or
     for determining rights to vote in respect of any such reorganization,
     reclassification, merger, consolidation, sale, transfer, disposition,
     dissolution, liquidation or winding up, and (ii) in the case of any such
     reorganization, reclassification, merger, consolidation, sale, transfer,
     disposition, dissolution, liquidation or winding up, at least 10-days'
     prior written notice of the date when the same shall take place. Such
     notice in accordance with the foregoing clause also shall specify (i) the
     date on which any such record is to be taken for the purpose of such
     dividend, distribution or right, the date on which the holders of Common
     Stock shall be entitled to any such dividend, distribution or right, and
     the amount and character thereof, and (ii) the date on which any such
     reorganization, reclassification, merger, consolidation, sale, transfer,
     disposition, dissolution, liquidation or winding up is to take place and
     the time, if any such time is to be fixed, as of which the holders of
     Common Stock shall be entitled to exchange their shares of Common Stock for
     securities or other property deliverable upon such reorganization,
     reclassification, merger, consolidation, sale, transfer, disposition,
     dissolution, liquidation or winding up. Each such written notice shall be
     sufficiently given if addressed to the Holder at the last address of the
     Holder appearing on the books of the Company and delivered in accordance
     with Section 11(d).

                                       -6-

<PAGE>

4. TRANSFER OF WARRANT. This Warrant may only be transferred in compliance with
federal and state securities laws; provided, however, that the Company may
withhold its consent to transfer or assignment of this Warrant to any person or
entity who is deemed to be a competitor or prospective competitor of the
Company, such determination to be made in the reasonable judgment of the Board.
If, at the time of the surrender of this Warrant in connection with any transfer
of this Warrant or the resale of the Warrant Stock, this Warrant or the Warrant
Stock, as applicable, shall not be registered under the Securities Act, the
Company may require, as a condition of allowing such transfer (i) that the
Holder or transferee of this Warrant or the Warrant Stock as the case may be,
furnish to the Company a written opinion of counsel that is reasonably
acceptable to the Company to the effect that such transfer may be made without
registration under the Securities Act, (ii) that the Holder or transferee
execute and deliver to the Company an investment letter in form and substance
acceptable to the Company and substantially in the form attached as Exhibit B
hereto and (iii) that the transferee be an "accredited investor" as defined in
Rule 501(a) promulgated under the Securities Act. Transfer of this Warrant and
all rights hereunder, in whole or in part, in accordance with the foregoing
provisions, shall be registered on the books of the Company to be maintained for
such purpose, upon surrender of this Warrant at the principal office of the
Company or the office or agency designated by the Company, together with a
written assignment of this Warrant substantially in the form of Exhibit C hereto
duly executed by the Holder or its attorney-in-fact and funds sufficient to pay
any transfer taxes payable upon the making of such transfer. Upon such surrender
and, if required, such payment, the Company shall execute and deliver a new
Warrant or Warrants in the name of the assignee or assignees and in the
denomination specified in such instrument of assignment, and shall issue to the
assignor a new Warrant evidencing the portion of this Warrant not so assigned,
and this Warrant shall promptly be cancelled. Following a transfer that complies
with the requirements of this Section 4, the Warrant may be exercised by a new
Holder for the purchase of shares of Common Stock regardless of whether the
Company issued or registered a new Warrant on the books of the Company. This
Section 4 shall survive the exercise or expiration of the Warrant.

5. CONDITIONS TO EXERCISE OF WARRANT.

          (A) Each certificate evidencing the Warrant Shares issued upon
     exercise of this Warrant shall be stamped or imprinted with a legend
     substantially in the following form:

          THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
          SECURITIES ACT OF 1933 (THE "ACT") AND MAY NOT BE OFFERED, SOLD OR
          OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL
          REGISTERED UNDER THE ACT OR, IN THE OPINION OF COUNSEL IN FORM AND
          SUBSTANCE SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER,
          SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS IN COMPLIANCE THEREWITH.

                                       -7-

<PAGE>

          (B) REMOVAL OF LEGEND AND TRANSFER RESTRICTIONS. Any legend endorsed
     on a certificate pursuant to this Section 5 shall be removed, and the
     Company shall issue a certificate without such legend to the holder of such
     Warrant Shares if (i) such Warrant Shares are resold pursuant to a
     registration statement under the Securities Act of 1933, as amended, and a
     prospectus meeting the requirements of Section 10 of the Securities Act is
     delivered or deemed delivered to the purchaser of such Warrant Shares, (ii)
     if such holder satisfies the requirements of Rule 144(k) or (iii) if such
     holder provides the Company with an opinion of counsel for such holder of
     the Warrant Shares, reasonably satisfactory to the Company, to the effect
     that a sale, transfer or assignment of such Warrant Shares may be made
     without registration. This paragraph shall survive any exercise of this
     Warrant.

          (C) RESTRICTIONS ON EXERCISE AMOUNT. Unless a Holder delivers to the
     Company irrevocable written notice (x) prior to the date of issuance hereof
     or 61 days prior to the effective date of such notice that this Section
     5(c) shall not apply to such Holder or (y) prior to a Change of Control,
     the Holder may not acquire a number of Warrant Shares to the extent that,
     upon such exercise, the number of shares of Common Stock then beneficially
     owned by such Holder and its affiliates and any other persons or entities
     whose beneficial ownership of Common Stock would be aggregated with the
     Holder's for purposes of Section 13(d) of the Securities Exchange Act of
     1934, as amended (the "EXCHANGE ACT"), (including shares held by any
     "group" of which the Holder is a member, but excluding shares beneficially
     owned by virtue of the ownership of securities or rights to acquire
     securities that have limitations on the right to convert, exercise or
     purchase similar to the limitation set forth herein) exceeds 9.99% of the
     total number of shares of Common Stock of the Company then issued and
     outstanding. For purposes hereof, "group" has the meaning set forth in
     Section 13(d) of the Exchange Act and applicable regulations of the
     Commission, and the percentage held by the holder shall be determined in a
     manner consistent with the provisions of Section 13(d) of the Exchange Act.
     Each delivery of a notice of exercise by a Holder will constitute a
     representation by such Holder that it has evaluated the limitation set
     forth in this paragraph and determined, based on the most recent public
     filings by the Company with the Commission, that the issuance of the full
     number of Warrant Shares requested in such notice of exercise is permitted
     under this paragraph.

6. FRACTIONAL SHARES. No fractional Warrant Shares will be issued in connection
with any exercise hereunder, but in lieu of such fractional shares the Company
shall make a cash payment therefor upon the basis of the Exercise Price then in
effect.

7. REGISTRATION RIGHTS. The Holder shall have the registration rights described
in the Registration Rights Agreement.

8. RIGHTS OF STOCKHOLDERS. No Holder shall be entitled, as a Warrant holder, to
vote or receive dividends or be deemed the holder of Warrant Shares or any other
securities of the Company which may at any time be issuable on the exercise
hereof for any purpose, nor shall anything contained herein be construed to
confer upon the Holder any of the rights of a stockholder of the Company or any
right to vote for the election of directors or upon any matter submitted to
stockholders at any meeting thereof, or to give or withhold consent to any
corporate action (whether upon any recapitalization, issuance of stock,
reclassification of stock, change of par value, consolidation, merger,
conveyance, or otherwise) or to receive dividends or

                                       -8-

<PAGE>

subscription rights or otherwise with respect to the Warrant Shares until this
Warrant shall have been exercised and the Warrant Shares purchasable upon the
exercise hereof shall have become deliverable, as provided herein.

9. TERM OF WARRANT. This Warrant shall become exercisable on the Warrant Date
and shall no longer be exercisable as of the earlier of (i) 5:00 p.m., San
Diego, California local time, on the date that is the five-year anniversary of
the Warrant Date; and (ii) upon consummation of a Change of Control.

10. REDEMPTION AT COMPANY'S ELECTION. The Company may at the option of the
Board, by at least seven-days' prior written notice to the Holder (the
"REDEMPTION NOTICE"), redeem this Warrant, in whole or in part, at any time,
provided that (i) the Daily Market Price for twenty consecutive trading days is
equal to or greater than the product of (x) 2 multiplied by (y) the Exercise
Price, (ii) either (A) all of the Warrant Shares underlying this Warrant to be
redeemed are then registered under an effective registration statement or (B)
may be sold pursuant to Rule 144 during a three-month period without
registration under the Securities Act, (iii) sufficient shares of Common Stock
of the Company are authorized and reserved for issuance upon the full exercise
of this Warrant, (iv) all of the Warrant Shares issuable upon exercise of this
Warrant are then listed on every stock exchange, market or bulletin board on
which any Common Stock of the Company is then listed and (v) the Company is not
in default of any material provision of any Transaction Agreement (as defined in
the Purchase Agreement). The Redemption Notice shall set forth a date, not less
than seven days after the date of the Redemption Notice, on which the redemption
of this Warrant shall occur (the "REDEMPTION DATE"). On the Redemption Date, (i)
the Company shall pay the Holder by certified check an amount equal to the
product of (x) $0.001 (as adjusted in proportion to any adjustment to the
Exercise Price pursuant to Section 3 hereof) multiplied by (y) the number of
Warrant Shares so redeemed; and (ii) the Holder shall deliver the original copy
of this Warrant marked "REDEEMED" to the Company. If the Company shall redeem
this Warrant in part, the Company shall, at the Redemption Date, provided that
the Holder shall have delivered the original copy of this Warrant marked
"REDEEMED" to the Company, deliver to the Holder a new Warrant evidencing the
rights of the Holder to purchase the unredeemed shares of Common Stock called
for by this Warrant, which new Warrant shall in all other respects be identical
with this Warrant. Nothing in this Section 10 shall prevent the exercise of the
Warrants at any time prior to the Redemption Date.

11. MISCELLANEOUS.

          (A) This Warrant is being delivered in the State of California and
     shall be construed and enforced in accordance with and governed by the laws
     of the State of California, without giving effect to principles of
     conflicts of laws.

          (B) The headings in this Warrant are for purposes of reference only,
     and shall not limit or otherwise affect any of the terms hereof.

          (C) The terms of this Warrant shall be binding upon and shall inure to
     the benefit of any successors or assigns of the Company and of the Holder
     and of the Warrant Shares issued or issuable upon the exercise hereof.

                                       -9-

<PAGE>

          (D) Any notice provided for or permitted under this Warrant shall be
     treated as having been given (a) upon receipt, when delivered personally or
     sent by confirmed facsimile or telecopy, (b) one day after sending, when
     sent by commercial overnight courier with written verification of receipt,
     or (c) three business days after deposit with the United States Postal
     Service, when mailed postage prepaid by certified or registered mail,
     return receipt requested, addressed (a) if to the Company, at 9948 Hibert
     Street, Suite 100, San Diego, CA 92131, facsimile: (858) 271-9678,
     Attention: Nicholas J. Virca, or, if to the Holder, at such address or
     facsimile number as the Holder shall have furnished to the Company in
     writing, or at such other place of which the other party has been notified
     in accordance with the provisions of this Section 11(d).

          (E) This Warrant constitutes the full and entire understanding and
     agreement between the parties with regard to the subjects hereof.

          (F) Upon receipt of evidence reasonably satisfactory to the Company of
     the loss, theft, destruction or mutilation of this Warrant and, in the case
     of any such loss, theft or destruction, upon delivery of an indemnity
     agreement reasonably satisfactory in form and amount to the Company or, in
     the case of any such mutilation, upon surrender and cancellation of such
     Warrant, the Company at the Holder's expense will execute and deliver to
     the holder of record, in lieu thereof, a new Warrant of like date and
     tenor.

          (G) This Warrant and any provision hereof may be amended, waived or
     terminated only by an instrument in writing signed by the Company and the
     Holder.

          (H) Receipt of this Warrant by the Holder shall constitute acceptance
     of and agreement to the foregoing terms and conditions.

                            [Signature page follows.]

                                      -10-

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by its
duly authorized officer.

Issued: April 8, 2004

                                        ADVENTRX PHARMACEUTICALS, INC.

                                        By: /s/ Nicholas J. Virca
                                            ------------------------------------
                                            Nicholas J. Virca
                                            President & CEO

           SIGNATURE PAGE TO THE A-2 WARRANT TO PURCHASE COMMON STOCK

<PAGE>

                                    EXHIBIT A

                               NOTICE OF EXERCISE

TO: ADVENTRX Pharmaceuticals, Inc.
    9948 Hibert Street, Suite 100
    San Diego, CA 92131

     1. The undersigned hereby elects to purchase ____________ shares of Common
Stock, par value $0.001 per share, of the Company ("COMMON STOCK") pursuant to
the terms of Section 1(b) of the A-2 Warrant to Purchase Common Stock dated
___________ 2004 (the "WARRANT"), and tenders herewith payment of the purchase
price of such shares in full.

     2. The undersigned hereby elects to convert the attached Warrant into
Common Stock of Adventrx Pharmaceuticals, Inc. through "cashless exercise" in
the manner specified in the Warrant. This conversion is exercised with respect
to _____________________ of the Shares covered by the Warrant.

     Please issue a certificate or certificates representing said _________
shares of Common Stock in the name of the undersigned or in such other name as
is specified below:

                                        Name:
                                              ----------------------------------
                                        Address:
                                                 -------------------------------

                                                 -------------------------------

     The undersigned hereby represents and warrants that the aforesaid shares of
Common Stock are being acquired for the account of the undersigned for
investment and not with a view to, or for resale, in connection with the
distribution thereof, and that the undersigned has no present intention of
distributing or reselling such shares, and that all representations and
warranties of the undersigned with respect to the Warrants and Warrant Shares
(as defined in the Warrant) set forth in Section 4 of the Purchase Agreement (as
defined in the Warrant) were true and correct as of the Warrant Date (as defined
in the Warrant) and are true and correct as of the date hereof.

                                        ----------------------------------------

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------
                                        Date:
                                              ----------------------------------

<PAGE>

                                    EXHIBIT B

                    FORM OF INVESTMENT REPRESENTATION LETTER

In connection with the acquisition of [warrants (the "Warrants") to purchase
_______ shares of Common Stock of ADVENTRX Pharmaceuticals, Inc. (the
"Company"), par value $0.001 per share (the "Common Stock")][________ shares of
Common Stock of ADVENTRX Pharmaceuticals, Inc. (the "Company"), par value $0.001
per share (the "Common Stock")], by _______________ (the "Holder") from
_____________, the Holder hereby represents and warrants to the Company as
follows:

The Holder (i) is an "Accredited Investor" as that term is defined in Rule 501
of Regulation D promulgated under the Securities Act of 1933, as amended (the
"Act"); and (ii) has the ability to bear the economic risks of such Holder's
prospective investment, including a complete loss of Holder's investment in the
Warrants and the shares of Common Stock issuable upon the exercise thereof
(collectively, the "Securities").

The Holder, by acceptance of the Warrants, represents and warrants to the
Company that the Warrants and all securities acquired upon any and all exercises
of the Warrants are purchased for the Holder's own account, and not with view to
distribution of either the Warrants or any securities purchasable upon exercise
thereof in violation of applicable securities laws.

The Holder acknowledges that (i) the Securities have not been registered under
the Act, (ii) the Securities are "restricted securities" and the certificate(s)
representing the Securities shall bear the following legend, or a similar legend
to the same effect, until (i) in the case of the shares of Common Stock
underlying the Warrants, such shares shall have been registered for resale by
the Holder under the Act and effectively been disposed of in accordance with a
registration statement that has been declared effective; or (ii) in the opinion
of counsel for the Company such Securities may be sold without registration
under the Act:

"[NEITHER] THE SECURITIES REPRESENTED BY THIS CERTIFICATE [NOR THE SECURITIES
INTO WHICH THEY ARE EXERCISABLE] HAVE [NOT] BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), AND ALL SUCH SECURITIES ARE SUBJECT TO
RESTRICTIONS ON TRANSFERABILITY AS SET FORTH IN THIS CERTIFICATE. [NEITHER] THE
SECURITIES REPRESENTED HEREBY [NOR THE SECURITIES INTO WHICH THEY ARE
EXERCISABLE] MAY [NOT] BE SOLD, TRANSFERRED, OR OTHERWISE DISPOSED OF IN THE
ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT OR AN OPINION OF
COUNSEL, REASONABLY ACCEPTABLE TO COUNSEL FOR THE COMPANY, TO THE EFFECT THAT
THE PROPOSED SALE, TRANSFER, OR DISPOSITION MAY BE EFFECTUATED WITHOUT
REGISTRATION UNDER THE ACT."

IN WITNESS WHEREOF, the Holder has caused this Investment Representation Letter
to be executed in its corporate name by its duly authorized officer this __ day
of __________ 200_.

[Name]

By:
    ---------------------------------
Name:
      -------------------------------
Title:
       ------------------------------

<PAGE>

                                    EXHIBIT C

                                 ASSIGNMENT FORM

FOR VALUE RECEIVED the undersigned registered owner of this Warrant for the
purchase of shares of Common Stock of ADVENTRX Pharmaceuticals, Inc. hereby
sells, assigns and transfers unto the Assignee named below all of the rights of
the undersigned under this Warrant, with respect to the number of shares of
common stock set forth below:

-------------------------------------

-------------------------------------

-------------------------------------
(Name and Address of Assignee)

-------------------------------------
(Number of Shares of Common Stock)

and does hereby irrevocably constitute and appoint ____________ attorney-in-fact
to register such transfer on the books of the Company, maintained for the
purpose, with full power of substitution in the premises.

Dated:
       ------------------------------

-------------------------------------
(Print Name and Title)

-------------------------------------
(Signature)

-------------------------------------
(Witness)

NOTICE: The signature on this assignment must correspond with the name as
written upon the face of the Warrant in every particular, without alteration or
enlargement or any change whatsoever.

<PAGE>

                           SCHEDULE OF WARRANTHOLDERS

     ADVENTRX Pharmaceuticals, Inc. issued this form of A-2 Warrant to Purchase
Common Stock to each of the persons listed below for the purchase of up to the
number of shares of Common Stock listed opposite such person's name below.

<TABLE>
<CAPTION>
HOLDER                                                   WARRANT NO.   SHARES
------                                                   -----------   ------
<S>                                                      <C>           <C>
Andrew J. Maffey                                            WA2-65      3,400
Centrum Bank AG                                             WA2-57      6,000
North Sound Legacy Institutional Fund LLC                   WA2-70      2,400
North Sound Legacy Institutional Fund LLC                   WA2-62     12,400
North Sound Legacy International Ltd.                       WA2-64     23,800
Robert J. Neborsky MD Inc Combination Retirement Trust      WA2-67     33,000
Robert J. Neborsky MD Inc Combination Retirement Trust      WA2-68     33,333
North Sound Legacy Institutional Fund LLC                   WA2-71        800
</TABLE>

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