Exchange Agent Agreement

Exhibit 99.7
EXCHANGE AGENT AGREEMENT
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AGREEMENT dated as of September 14, 1995 between Cytogen Corporation, a Delaware corporation ("Cytogen"), and Mellon Securities Trust Company, a New York trust company ("Mellon").


WHEREAS, Cytogen, Cellcor Acquisition Corp., a Delaware corporation (the "Merger Subsidiary"), and Cellcor, Inc., a Delaware corporation ("Cellcor"), are parties to an Agreement and Plan of Merger dated June 15, 1995, as amended (the "Merger Agreement"), pursuant to which, (i) Cellcor will be merged with and into the Merger Subsidiary (the "Merger"), and the Merger Subsidiary will change its name to Cellcor, Inc., and (ii) each then outstanding share of Cellcor common stock, par value $.01 per share ("Cellcor Common Stock") (other than shares held by Cellcor as treasury stock or by Cytogen or the Merger Subsidiary), will be converted into the right to receive .60 shares of Cytogen common stock, par value $.01 per share ("Cytogen Common Stock"), and each then outstanding share of Cellcor Convertible Preferred Stock, par value $.01 per share ("Cellcor Preferred Stock") (other than shares held by Cellcor as treasury stock or by Cytogen or the Merger Subsidiary), will be converted into the right to receive 218.94 shares of Cytogen Common Stock (together with any cash payable in lieu of fractional shares of Cytogen Common Stock, collectively, the "Merger Consideration").


WHEREAS, the Merger is subject to the satisfaction or waiver of certain conditions to the closing set forth in the Merger Agreement, including that (i) Cytogen stockholders approve the issuance of Cytogen Common Stock in the Merger, and (ii) the holders of a majority of the outstanding shares of Cellcor Common Stock and the holders of 66-2/3% of the outstanding shares of Cellcor Preferred Stock, voting separately as two classes, approve the Merger.


WHEREAS, Cytogen desires to retain Mellon to serve as the exchange agent (the "Exchange Agent") with respect to the surrender of certificates representing Cellcor Common Stock and Cellcor Preferred Stock in exchange for the Merger Consideration pursuant to the Merger.


NOW, THEREFORE, the parties agree as follows:


1. The Merger. Upon satisfaction or waiver of each of the conditions to
----------- the Merger set forth in the Merger Agreement, Cellcor will be merged with and into the Merger Subsidiary. The


time at which the Merger will become effective is hereinafter referred to as the "Effective Time." The Exchange Agent will be informed by Cytogen of the occurrence of the Effective Time on such date. In carrying out its duties as Exchange Agent in connection with the Merger, the Exchange Agent is to act in accordance with the following:


(a) As soon as practicable after the Effective Time, the Exchange Agent
will mail by first class mail to each holder of record of Cellcor
Common Stock and Cellcor Preferred Stock as of the Effective Time
(collectively, the "Cellcor Stockholders") the following materials:


(i) A letter substantially in the form attached hereto as
Exhibit A, dated the date of the Effective Time, advising
Cellcor Stockholders that the Merger has become effective
and describing how such Cellcor Stockholders may exchange
their shares of Cellcor Common Stock or Cellcor Preferred
Stock, as the case may be (collectively, the "Former
Shares"), for the Merger Consideration.


(ii) A Letter of Transmittal substantially in the form attached
hereto as Exhibit B, to be executed by Cellcor
Stockholders and returned to the Exchange Agent with such
holders' certificates representing shares of Cellcor
Common Stock or Cellcor Preferred Stock.


(iii) Return envelopes addressed to the Exchange Agent.


(b) The Exchange Agent is to examine the Letters of Transmittal and
certificates for the Former Shares received by it to ascertain whether
the Letters of Transmittal are filled out and executed in accordance
with instructions set forth therein and that certificates for the
Former Shares represent validly issued and outstanding Cellcor Common
Stock or Cellcor Preferred Stock, as the case may be. In each case
where the Letter of Transmittal has been improperly filled out or
executed or, for any other reason, is not in proper form, or some
other irregularity exists, the Exchange Agent will endeavor to take
such action as may be necessary to cause such irregularity to be
corrected. All questions as to the form of documents


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and the eligibility for exchange of Cellcor Common Stock or Cellcor
Preferred Stock, as the case may be, in connection with the Merger
will be determined by Cytogen, in its sole discretion, which
determination shall be final and binding.


With the written approval of any of the employees of Cytogen
identified or named in Section 6(a) of this Agreement, or any other
person designated by Cytogen, the Exchange Agent is authorized to
waive irregularities in connection with the exchange of the Former
Shares pursuant to the Merger.


(c) The Exchange Agent will issue, register, countersign and mail by
first-class mail, insured under a blanket surety bond protecting the
Exchange Agent and Cytogen from loss or liability arising out of non-
receipt or non-delivery (or by registered mail insured separately), to
the Cellcor Stockholders submitting (i) valid certificates for Cellcor
Common Stock accompanied by properly executed Letters of Transmittal,
certificates for whole shares of Cytogen Common Stock in the number
equal to the product of (x) the number of shares of Cellcor Common
Stock for which certificates are surrendered and (y) .60 and (ii)
valid certificates for Cellcor Preferred Stock accompanied by properly
executed Letters of Transmittal, certificates for whole shares of
Cytogen Common Stock in the number equal to the product of (x) the
number of shares of Cellcor Preferred Stock for which certificates are
surrendered and (y) 218.94, along with any checks for Fractional
Proceeds (as defined in Section 1(d) hereof) and any Post-Merger
Distributions (as defined in, and as provided for, in Section 1(e)
hereof), and will cancel the Former Shares so surrendered, all in
accordance with Section 2.2 of the Merger Agreement. The Exchange
Agent will establish a stockholder register file consisting of an open
stockholder account detail for those holders remaining on the
stockholder register of Bank of Boston, Cellcor's transfer agent at
the Effective Time (the "Share Register"), and debit the share
certificates from the register as they are presented for exchange.


(d) With respect to any fractional share interests created when the number
of shares of Cytogen Common Stock issuable to any Cellcor Stockholder
exchanging Former


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Shares are not whole shares (after taking into account all
certificates representing Cellcor Common Stock or Cellcor Preferred
Stock delivered by a holder) (such holder, a "Fractional
Stockholder"), no fractional shares to which such Fractional
Stockholders would otherwise be entitled will be issued and in lieu
thereof, the Exchange Agent, as agent for the Fractional Stockholders,
will remit to each Fractional Stockholder cash in lieu of fractions,
without interest ("Fractional Proceeds"), in an amount equal to (i)
the applicable fractional part of a share of Cytogen Common Stock
multiplied by (ii) the average of the last reported sales prices of
Cytogen Common Stock as reported on the Nasdaq National Market, on
each of the ten trading days immediately preceding the date of the
Effective Time, in accordance with Section 2.2.5 of the Merger
Agreement, and mail a check or checks for the Fractional Proceeds
along with any full share certificates representing Cytogen Common
Stock as provided ...