Amendment to Section 4.2 of Development, Manufacturing and Marketing Agreement between Baxter Healthcare Corporation and Cerus Corporation

Baxter

VIA FAX
June 28, 2001

Cerus Corporation
2411 Stanwell Drive
Concord, CA 94520

                                Re:          Amendment to Section 4.2 of the June 30, 1998 Development Agreement

Ladies and Gentlemen:

Baxter Healthcare Corporation, a Delaware corporation (“Baxter”) is a party to that certain Development, Manufacturing and Marketing Agreement with Cerus Corporation, a Delaware corporation (“Cerus”), originally dated April 1, 1996, as amended and restated June 30, 1998 (the “Agreement”). Section 4.2 of the Agreement sets forth certain “standstill” obligations on the part of Baxter and its “Affiliates” (as that term is defined in Section 2, sub-heading “Baxter”), as to Cerus equity securities.

Baxter hereby agrees, convenants and consents that all references in Section 4.2 of the Agreement to “twenty and one-tenth percent” or “20.1%” shall, as of the date of this letter, be amended to read “five and four-tenths percent”, or “5.4%” respectively.

No other term of the Agreement shall be deemed amended hereby.

It is understood that our consent to these changes effectively renders any Cerus equity securities acquired by Baxter in excess of this newly lowered 5.4% threshold “Prohibited Securities” as that term is defined in the Agreement.

Sincerely,