Gary Patou, M.D. 26353 Esperanza Drive Los Altos, CA 94022 Dear Gary,

Exhibit 10.5

Xxxx Xxxxx, M.D.

00000 Xxxxxxxxx Xxxxx

Los Altos, CA 94022

Dear Xxxx,

As we have discussed, with respect to the Letter Agreement signed by you and the Company dated January 11, 2004 (the “Letter Agreement”), we both agree that the Letter Agreement will continue to govern any consulting services you agree to provide to the Company and that effective July 1, 2006 Section 2(iii) of the Letter Agreement signed is amended to reflect (i) an increase in the hourly consulting rate from $350 to $450 and (ii) $4,000 daily maximum compensation.

Please confirm your agreement with the change by countersigning as provided below.

We look forward to your continued guidance and leadership on the Advisory Committee project team.

Sincerely,

/s/ Xxxxxx Xxxx

Xxx Xxxx

Vice President

Human Resources

AGREED AND ACKNOWLEDGED:

/s/ Xxxx Xxxxx

Xxxx Xxxxx, M.D.