**Exhibit
      4.3**




**AMENDING
      AGREEMENT**




**THIS
      AMENDING AGREEMENT** made as
      of September 5, 2006.




B
      E T W E
      E N:




**Tm
      Bioscience Corporation** ,
      a
      corporation incorporated under the laws of the Province of Ontario




(hereinafter
      referred to as the “ **Corporation** ”)




-and-




**Gregory
      C. Hines**




an
      individual residing in the Province of Ontario




(hereinafter
      referred to as the “ **Executive** ”)




**WHEREAS** the
      Corporation and the Executive are parties to an employment agreement dated January
      1, 2005 (the
“ **Employment
      Agreement** ”);




**AND
      WHEREAS** the
      Corporation is concurrently with the execution of this Agreement granting to
      the
      Executive 293,192 options to purchase common shares in the capital of the
      Corporation pursuant to the terms and conditions of the Corporation’s Stock
      Option Plan (“ **ESOP** ”);




**AND
      WHEREAS** the
      Executive understands and agrees that his receipt of such stock options granted
      pursuant to the ESOP is conditional upon his agreement to observe the
      restrictive covenants contained in this Agreement;




**NOW,
      THEREFORE,** in
      consideration of the promises and mutual covenants herein, and other good and
      valuable consideration, the receipt and sufficiency of which is hereby
      acknowledged, the parties hereto agree as follows:




**ARTICLE 1**


**INTERPRETATION**




**Section 1.1**  **Incorporation
      of Employment Agreement.**




This
      Amending Agreement is supplemental to and shall be read in conjunction with
      the
      Employment Agreement, and the Employment Agreement and this Amending Agreement
      shall have effect so far as practicable as if all the provisions thereof and
      hereof were contained in one document.







**Section 1.2**  **Effect
      on the Employment Agreement.**




Except
      as
      specifically amended in the Amending Agreement, the Employment Agreement and
      its
      terms and conditions shall remain in full force and effect and are hereby
      ratified and confirmed.






**ARTICLE 2**


**EFFECTIVE
      DATE OF AMENDMENTS**




**Section 2.1**  **Effective
      Date of the Amendments.**




The
      amendments contained in this Amending Agreement shall become effective on
      September 5, 2006 and shall remain in effect until otherwise agreed to in
      writing by the parties or upon the termination of the Executive’s employment for
      any reason, whichever occurs first.






**ARTICLE 3**


**AMENDMENTS
      TO THE EMPLOYMENT AGREEMENT**




**Section 3.1**  **Amendment
      to Section 1.1 - Definitions**




(1)
            The
                definitions of “Change of Control” and “Change of Control Notice Period”
                contained in the Employment Agreement are hereby
                deleted.




(2)
            The
                definition of “Notice Period” contained in the Employment Agreement is
                hereby deleted and substituted with the
                following:




“ **Notice
      Period** ”
shall
      mean the period from the date on which the Executive was advised of the
      termination of his employment without Cause until twenty-four (24) months
      following the date of termination.




(3)
            The
                definition of “Period” contained in the Employment Agreement is hereby
                deleted and substituted with the
                following:




“ **Period** ”
means
      the period commencing on the Effective Date and ending (i) one (1) year
      following the date of termination of the Executive’s employment with the
      Corporation for any reason.




**Section 3.2**  **Amendments
      to Article 4**




(1)
            Sections
                4.3, 4.4., 4.5 and 4.6 are hereby deleted and substituted with the
                following:




**Section
      4.3**




Following
      the termination of the Executive’s employment for any reason whatsoever, the
      Executive hereby agrees to resign from any offices, positions and directorships
      which he may have or may have held in the Corporation or in
      any of its affiliates or associates.







**Section
      4.4**




Each
      of
      the Corporation and the Executive confirms that the provisions of Section 4.2(c)
      are reasonable and that the length of the notice of termination or the total
      amount payable, if any, as outlined therein has been agreed between them, or
      in
      the alternative is a reasonable pre-estimate of the damages which will be
      suffered by the Executive in the event of a termination without Cause, or a
      resignation for Good Reason and shall not be construed as a
      penalty.




**Section
      4.5**




In
      the
      event that the Corporation, in its sole discretion, determines that, without
      the
      express written consent of the Corporation, the Executive has breached any
      provisions of Sections 5, 6, 7, 8, 10 and 11, the Corporation shall have the
      right to suspend or terminate any or all remaining payments and/or benefits,
      if
      any, referenced in Section 4.2(c) of this Agreement. Such suspension or
      termination of payments and /or benefits shall be in addition to and shall
      not
      limit any and all other rights and remedies as set out in Section 9.1 of this
      Agreement that the Corporation may have against the Executive.






**ARTICLE 4**


**MISCELLANEOUS**




**Section 4.1**  **Independent
      Legal Advice.**




The
      Employee acknowledges, having been given sufficient opportunity to seek
      independent legal advice concerning the meaning and legal effect of this
      Amending Agreement. The Employee acknowledges that he understands the nature
      and
      consequences of this Amending Agreement.




**Section 4.2**  **Impact
      on Articles 6 and 7 of the Employment Agreement.**




(1)
            The
                Executive acknowledges and agrees that the above noted amendment
                to the
                definition of Notice Period in Article 1.1 impacts the length of
                the
                period during which the Executive is restricted from competing and/or
                soliciting pursuant to the restrictive covenants contained in Articles
                6
                and 7 of the Employment Agreement.







**Section 4.3**  **Counterparts.**




This
      Amending Agreement may be executed in any number of counterparts and all such
      counterparts taken together shall be deemed to constitute one and the same
      instrument.




**IN
      WITNESS WHEREOF** ,
      the
      parties hereto have executed this Amending Agreement as of the date first
      specified above.




/s/
                Bo Yoon
            
            /s/
                Gregory HinesWitness
            
            Gregory
                Hines


**T****m****BIOSCIENCE CORPORATION**By:
            /s/ James
              PelotJames
              PelotChief
              Financial Officer and Chief Operating
              Officer