Redacted Version

[**] CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH
RESPECT TO THE OMITTED PORTIONS.

SECOND AMENDMENT AGREEMENT

This Second Amendment Agreement is made and dated as of June 15, 2001 between Schering Aktiengesellschaft ("Schering") and Chiron Corporation
("Chiron").

WHEREAS,
Schering and Chiron have entered into the Regulatory Filing, Development and Supply Agreement as of May 10, 1993 and the Amendment Agreement (HDS Fees and Deeply
Discounted Vials) as of September 23, 1997 (the Regulatory Filing, Development and Supply Agreement as amended by the Amendment Agreement being hereinafter referred to as the "RFDS Agreement");
and

WHEREAS,
Schering and Chiron have entered into a Term Sheet as of January 31, 2001 (the "Term Sheet") pursuant to which the Parties agreed to amend certain terms of the RFDS
Agreement relating to the establishment and qualification by Chiron of a second production site and to the supply of Betaseron; and

WHEREAS,
Schering and Chiron wish to amend the RFDS Agreement to reflect the terms of the Term Sheet.

NOW
THEREFORE, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties agree as follows:

Capitalized
terms used in this Second Amendment Agreement and not defined herein shall have the meanings assigned to them in the RFDS Agreement.

SECTION ONE: AMENDMENTS TO ARTICLE ONE: DEFINITIONS ARTICLE

Reference is made to Article 1 of the RFDS Agreement (entitled "Definitions").

1.1Additional Definitions. The Parties agree to amend Article 1 of the RFDS Agreement to add the following new definitions in
the appropriate numerical order.



1.2Amended Definitions. The Parties agree to amend Article 1 of the RFDS Agreement to delete in their entirety Sections 1.4,
1.21 and 1.22 and to replace such Sections with the following Sections.



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SECTION TWO: AMENDMENTS TO ARTICLE VNON-CHIRON SUPPLY OF BETASERON

Reference is made to Article V of the RFDS Agreement (entitled "Non-Chiron Supply of Betaseron").

2.1
BI. The Parties agree to amend Article V of the RFDS Agreement to delete in its entirety Section 5.1 and to replace it with the following Section.



2.2Payments to Chiron: The Parties agree to further amend Article V of the RFDS Agreement to add the following
Section 5.3.



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For
the avoidance of doubt, it is hereby agreed and declared that the above provisions of this Section 5.3 do not apply to: (i) Net Sales by Schering of Product
comprising Betaseron which Schering is obliged to purchase from BI under the Amended BI Agreement in excess of the minimum quantities provided for in the Amended BI Agreement, to which the provisions
of Section 7.14 apply; or (ii) Net Sales by Schering of Product comprising Betaseron which Schering is entitled to purchase from BI pursuant to any extension of the Amended BI Agreement
between [**] or pursuant to any other supply agreement entered into by Schering as authorized under Section 7.3.4, to which the provisions of
Section 7.3.4(iii) shall apply. Schering shall have the right to audit the Chiron Variable Cost according to the provisions of Section 10.2.3.

SECTION THREE: AMENDMENTS TO ARTICLE SEVEN: SUPPLY OF PRODUCT

Reference is made to Article VII of the RFDS Agreement (entitled "Supply of Product").

3.1Supply Amendments.The Parties agree to amend Article VII to delete in their entirety Sections 7.2, 7.3 and 7.4 and to
replace them with the following Sections:



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| |  | .2 |  | By [**], the conditions set forth in Section 7.3.1 shall all be fully satisfied and Chiron, with the assistance of Schering as contemplated herein, shall have filed applications and commenced the process of obtaining
FDA Licensing and such other regulatory approvals set forth in Section 7.3.1(b)(iv) for the facilities necessary to meet the Worldwide Target. If, by [**], the conditions set forth in Section 7.3.1 shall all be fully satisfied and
Chiron can demonstrate that it has been and is proceeding with all reasonable due diligence to file the applications and commence the process of obtaining FDA Licensing and other regulatory approvals referred to in this Section 7.3.2, then the
deadline for meeting the conditions of this Section 7.3.2 shall be extended by a period of [**].
| |  | -- |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| |  | .3 |  | By [**], the conditions set forth in Sections 7.3.1 and 7.3.2 shall all be fully satisfied and the regulatory approvals shall have been obtained as set forth in Section 7.3.1(b)(iv) for the facilities necessary to meet the Worldwide Target.
If, by [**], such approvals have not been obtained, but the applicable agencies have neither rejected such application for such approval nor indicated that approval will not be granted, then Phase I shall continue and the start of Phase II shall be
delayed for up to one year until such approval is obtained. If approval is not obtained within [**], or at such earlier date if the application for approval is rejected, Phase II shall not commence and this condition shall not have been
satisfied.                                                   
| |  | .4 |  | (i)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
| |  |    |  | (ii)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

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| |  |    |  | (iii)                                                                                                                                                                                                                                |  | Notwithstanding any other term of this Agreement (including Sections 9.4 and 9.5), in the event that Schering shall exercise its rights under Section 7.3.4(i) or Section 7.3.4(ii) to purchase Betaseron from BI or another third
party, Chiron shall receive as [**] on account of such [**] an amount equal to [**] thereof during the term of this Agreement and [**].
| |  | -- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| |  | .5 |  | Chiron shall advise Schering as soon as practicable (a) if it is unable or does not elect to satisfy the conditions to Phase II set forth in Section 7.3, and (b) of the occurrence of any of the events set forth in
Section 7.3.3.



SECTION FOUR: AMENDMENTS TO ARTICLE 9: PAYMENTS

Reference is made to Article IX of the RFDS Agreement (entitled "Payments").

3.1Supply Amendments. The Parties agree to amend Article IX to delete in its entirety Section 9.4 and to replace it with
the following Section:



SECTION FIVE: MISCELLANEOUS

5.1 Effective Date.This Second Amendment Agreement shall be effective from and after
[**]. From and after [**], all references to the RFDS Agreement shall be deemed to be references to such agreement as amended by this Second Amendment
Agreement.

5.2 Term Sheet.This Second Amendment Agreement supersedes the terms of the Term Sheet.

5.3 Scope of Amendment.This Second Amendment Agreement is limited as specified herein and shall not constitute a waiver, modification
or amendment of any other provision of the RFDS Agreement, which shall continue in full force and effect except as set forth herein.

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5.4 Applicable Law.This Second Amendment Agreement shall be governed by, subject to and construed in accordance with the laws of the
State of California and the Parties consent to the jurisdiction of the courts of that state. Except as set forth expressly herein, no dispute shall be submitted to arbitration without the advance
written consent of both Parties.

5.5 Counterparts. This Second Amendment Agreement may be executed in two or more counterparts (and via facsimile), each of which shall
constitute an original, but all of which, when taken together, shall constitute but one instrument.

5.6 Headings.The section headings contained in this Second Amendment Agreement are included for convenience only and form no part of
the agreement between the Parties.

5.7 Construction.This Second Amendment Agreement is the product of mutual negotiation and is not to be construed strictly against
either Party.

IN
WITNESS WHEREOF, the Parties have executed this Second Amendment Agreement as of the date first written above.

|SCHERING AKTIENGESELLSCHAFT |                                                 |  |         | CHIRON CORPORATION
|--------------------------- | ----------------------------------------------- |  | ------- | ------------------
|By                          | /s/ILLEGIBLETitleIndustrial Operations & Envir. |  | 15-6-01 |                   
|By                          | /s/ILLEGIBLETitleIT & Controlling PPh           |  |         |                   

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APPENDIX 1    Key Terms of BI Amendment Agreement

|           |  |              
|---------- |  | -------------
|[**] vials |  | [**] per vial
|[**] vials |  | [**] per vial
|[**] vials |  | [**] per vial
|[**] vials |  | [**] per vial



[**] CERTAIN INFORMATION IN THIS EXHIBIT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS BEEN REQUESTED WITH
RESPECT TO THE OMITTED PORTIONS.

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