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Exhibit 4.2
 
 IDM INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE This Certifies that SEE REVERSE FOR CERTAIN DEFINITIONS CUSIP 449394 10 5 is the record holder of FULLY PAID AND NONASSESSABLE SHARES OF COMMON STOCK, $.01 PAR VALUE, OF IDM Pharma, Inc. transferable on the books of the Corporation by the holder hereof in person or by duly authorized
attorney upon surrender of this certificate properly endorsed. This certificate is not valid until
countersigned by the Transfer Agent and registered by the Registrar. WITNESS the facsimile seal of the Corporation and the facsimile signatures of its duly
authorized officers. Dated: nnnnnnnn nn nnn SENIOR VP, FINANCIAL OFFICER
PRESIDENT AND CHIEF EXECUTIVE OFFICER
COUNTERSIGNED            AND REGISTERED:
AMERICAN            STOCK TRANSFER & TRUST COMPANY
(New York, NY) TRANSFER AGENT AND REGISTRAR
BY
AUTHORIZED            SIGNATURE AMERICAN            BANK            NOTE            COMPANYPRODUCTION            COORDINATOR: DENISE            HOPKINS 931-490-1714
711 ARMSTRONG            LANEPROOF OF            MARCH 11, 2008 COLUMBIA, TENNESSEE 38401 IDM            PHARMA, INC.
(931) 388-3003 TSB 29593 FC
SALES: E. BUCKLEY 951-340-1950 Operator: R/AP
/ ETHER 7 / LIVE JOBS / I / PHARMA 29593 FC            Rev. 1
IDM COLORS SELECTED FOR PRINTING: Logo prints PMS 5415 Blue and Black. Intaglio prints in SC-7 dark
blue. COLOR: This proof was printed from a digital file or artwork on a graphics quality, color laser
printer. It is a good representation of the color as it will appear on the final product. However,
it is not an exact color rendition, and the final printed product may appear slightly different
from the proof due to the difference between the dyes and printing ink. PLEASE INITIAL THE APPROPRIATE SELECTION FOR THIS PROOF: OK AS IS OK WITH CHANGES MAKE CHANGES
AND SEND ANOTHER PROOF




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TEN COM
    
     as tenants in common
    
    
    
    UNIF GIFT MIN ACT 
    
    
    
    CustodianTEN ENT
    
     as tenants by the entireties
    
    
    
    
    
    (Cust)
    
    
    
    (Minor)JT TEN
    
     as joint tenants with right of
    
    
    
    
    
    under Uniform Gifts to Minorssurvivorship and not as tenants
    
    
    
    Actin common
    
    
    
    
    
    
    
    (State)COM PROP
    
     as community property
    
    
    
    UNIF TRF MIN ACT 
    
    
    
    Custodian (until age
    
    )(Cust)under Uniform Transfers(Minor)to Minors Act(State)
  For Value Received,
    
    
    
    hereby sell(s), assign(s) and transfer(s) unto
 PLEASE INSERT SOCIAL SECURITY OR OTHERIDENTIFYING NUMBER OF ASSIGNEE
  
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)shares of the capital stock represented by the within Certificate, and do hereby irrevocably constitute
and appointattorney-in-fact to transfer the said stock on the books of the within named Corporation with full power of
substitution in the premises.Dated
 THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OFNOTICE:
    
    THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGEWHATSOEVER.
  THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION, (BANKS, STOCKBROKERS,
SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE
MEDALLION PROGRAM), PURSUANT TO S.E.C. RULE 17Ad-15.