UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549





FORM 10-Q/A

(Amendment No. 1)





(Mark One)

|x | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ---------------------------------------------------------------------------------------

For the Quarterly Period Ended March 31, 2011

OR



| ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

Commission File Number 0-26483





diaDexus, Inc.

(Exact name of Registrant as Specified in its Charter)







|                                                               |  |                                     
|-------------------------------------------------------------- |  | ------------------------------------
|Delaware                                                       |  | 94-3236309                          
|(State or other jurisdiction of
incorporation or organization) |  | (I.R.S. Employer Identification No.)
|                                                               | 
|343 Oyster Point Boulevard South San Francisco, California     |  | 94080                               
|(Address of principal executive offices)                       |  | (Zip Code)                          

(650) 246-6400

(Registrants telephone number, including area code)





Indicate by check mark whether
the issuer (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90
days.    Yes  x    No   ̈

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405
of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such
files).    Yes   ̈    No   ̈

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of large accelerated
filer, accelerated filer and smaller reporting company in Rule 12b-2 of the Exchange Act. (Check one)



|                        |  |                                                  |  |                           |  |  
|----------------------- |  | ------------------------------------------------ |  | ------------------------- |  | -
|Large accelerated filer |  |  ̈                                                |  | Accelerated filer         |  |  ̈
|                        |  |                                                  | 
|Non-accelerated filer   |  |  ̈  (Do not check if a smaller reporting company) |  | Smaller Reporting Company |  | x

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act).    Yes   ̈    No  x

The number of shares outstanding of the registrants common stock, $0.01 par value per share, was 53,067,057 as of May 6, 2011.









---

Explanatory Note

This Amendment No. 1 on Form 10-Q/A (Amendment) amends the Quarterly Report on Form 10-Q of diaDexus, Inc. (the Company) for the first fiscal quarter ended March 31,
2011, which was originally filed on May 13, 2011 (the Q1 Form 10-Q). The Company is filing this Amendment solely for the purpose of re-filing Exhibits 10.1, 10.2, 10.4, 10.5 and 10.6 in connection with a request for confidential
treatment. This Amendment does not modify or update any part of or information set forth in the Q1 Form 10-Q other than Exhibits 10.1, 10.2, 10.4, 10.5 and 10.6.

PART II  OTHER INFORMATION



|Item 6. | Exhibits
|------- | --------

The following exhibits are
filed as part of this report:



|        |  |                                                                                                                                                                                                                                                                                                                                                                                                 
|------- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Exhibit |  | Description                                                                                                                                                                                                                                                                                                                                                                                     
|        | 
|2.1*    |  | Agreement and Plan of Merger and Reorganization, dated May 28, 2010, by and among VaxGen, Inc., Violet Acquisition Corporation, Violet Acquisition LLC, diaDexus, Inc. and John E.
Hamer, as the agent of diaDexus, Inc.s stockholders (incorporated by reference to Exhibit 2.1 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on June 1, 2010)                     
|        | 
|2.2     |  | Amendment No. 1 to Agreement and Plan of Merger and Reorganization, dated June 24, 2010, by and among VaxGen, Inc., Violet Acquisition Corporation, Violet Acquisition LLC, diaDexus,
Inc., and John E. Hamer as the agent of diaDexus, Inc.s stockholders (incorporated by reference to Exhibit 2.1 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on June 28, 2010)
|        | 
|3.1     |  | Restated Certificate of Incorporation of the registrant (incorporated by reference to Exhibit 3.1 to the registrants Quarterly Report on Form 10-Q (file no. 0-26483) for the
fiscal quarter ended September 30, 2010, filed on November 15, 2010)                                                                                                                                             
|        | 
|3.2     |  | Certificate of Change of Registered Agent and Registered Office (incorporated by reference to Exhibit 3.1 to the registrants Current Report on Form 8-K (file no. 0-26483),
filed on January 25, 2011)                                                                                                                                                                                         
|        | 
|3.3     |  | Amended and Restated Bylaws of the registrant (incorporated by reference to Exhibit 3.2 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on
November 5, 2010)                                                                                                                                                                                                           
|        | 
|10.1**  |  | Distribution Agreement, effective as of January 1, 2011 (the Inova Agreement), by and between diaDexus, Inc. and Inova Diagnostics, Inc.                                                                                                                                                                                                                                                      
|        | 
|10.2**  |  | 2011 Special Programs Addendum to the Inova Agreement, effective as of January 1, 2011                                                                                                                                                                                                                                                                                                          
|        | 
|10.3**+ |  | First Amendment to the Inova Agreement, effective as of January 1, 2011                                                                                                                                                                                                                                                                                                                         
|        | 
|10.4    |  | Addendum No. 3 to the Master Supply Agreement, effective as of April 1, 2011, by and between diaDexus, Inc. and Berkeley HeartLab, Inc.                                                                                                                                                                                                                                                         
|        | 
|10.5**  |  | Purchase Agreement, effective as of January 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                                                            
|        | 
|10.6**  |  | Volume Discount Addendum to the Purchase Agreement, effective as of January 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                            
|        | 
|10.7+   |  | Volume Discount Addendum No. 2 to the Purchase Agreement, effective as of April 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                        



---

|      |  |                                                                                                                                                  
|----- |  | -------------------------------------------------------------------------------------------------------------------------------------------------
|      | 
|31.1  |  | Certification of Chief Executive Officer pursuant to Exchange Act Rule 13a-14(a)                                                                 
|      | 
|31.2  |  | Certification of Chief Financial Officer pursuant to Exchange Act Rule 13a-14(a)                                                                 
|      | 
|32.1+ |  | Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
|      | 
|32.2+ |  | Certification of Chief Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002



|* | Certain schedules referenced in the Agreement and Plan of Merger and Reorganization have been omitted in accordance with Item 601(b)(2) of Regulation S-K. A copy
of any omitted schedule will be furnished supplementally to the Securities and Exchange Commission upon request.
|- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|** | Certain portions have been omitted pursuant to a confidential treatment request. Omitted information has been filed separately with the SEC.
|-- | --------------------------------------------------------------------------------------------------------------------------------------------

|+ | Filed with the Q1 Form 10-Q.
|- | ----------------------------



---

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.



|      |  |              |  |     |  |                                                                
|----- |  | ------------ |  | --- |  | ---------------------------------------------------------------
|      |  |              |  |     |  | diaDexus, Inc.                                                 
|      |  |              | 
|Date: |  | July 7, 2011 |  | By: |  | /s/ James P. Panek                                             
|      |  |              |  |     |  | James P. Panek                                                 
|      |  |              |  |     |  | Interim President and Chief Executive Officer                  
|      |  |              | 
|Date: |  | July 7, 2011 |  | By: |  | /s/ David J. Foster                                            
|      |  |              |  |     |  | David J. Foster                                                
|      |  |              |  |     |  | Executive Vice President, Chief Financial Officer and Secretary



---

EXHIBIT INDEX



|           |  |                                                                                                                                                                                                                                                                                                                                                                                                 
|---------- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|ExhibitNo. |  | Description                                                                                                                                                                                                                                                                                                                                                                                     
|           | 
|2.1*       |  | Agreement and Plan of Merger and Reorganization, dated May 28, 2010, by and among VaxGen, Inc., Violet Acquisition Corporation, Violet Acquisition LLC, diaDexus, Inc. and John
E. Hamer, as the agent of diaDexus, Inc.s stockholders (incorporated by reference to Exhibit 2.1 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on June 1, 2010)                     
|           | 
|2.2        |  | Amendment No. 1 to Agreement and Plan of Merger and Reorganization, dated June 24, 2010, by and among VaxGen, Inc., Violet Acquisition Corporation, Violet Acquisition LLC,
diaDexus, Inc., and John E. Hamer as the agent of diaDexus, Inc.s stockholders (incorporated by reference to Exhibit 2.1 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on June 28, 2010)
|           | 
|3.1        |  | Restated Certificate of Incorporation of the registrant (incorporated by reference to Exhibit 3.1 to the registrants Quarterly Report on Form 10-Q (file no. 0-26483) for the
fiscal quarter ended September 30, 2010, filed on November 15, 2010)                                                                                                                                             
|           | 
|3.2        |  | Certificate of Change of Registered Agent and Registered Office (incorporated by reference to Exhibit 3.1 to the registrants Current Report on Form 8-K (file no. 0-26483),
filed on January 25, 2011)                                                                                                                                                                                         
|           | 
|3.3        |  | Amended and Restated Bylaws of the registrant (incorporated by reference to Exhibit 3.2 to the registrants Current Report on Form 8-K (file no. 0-26483), filed on
November 5, 2010)                                                                                                                                                                                                           
|           | 
|10.1**     |  | Distribution Agreement, effective as of January 1, 2011 (the Inova Agreement), by and between diaDexus, Inc. and Inova Diagnostics, Inc.                                                                                                                                                                                                                                                      
|           | 
|10.2**     |  | 2011 Special Programs Addendum to the Inova Agreement, effective as of January 1, 2011                                                                                                                                                                                                                                                                                                          
|           | 
|10.3**+    |  | First Amendment to the Inova Agreement, effective as of January 1, 2011                                                                                                                                                                                                                                                                                                                         
|           | 
|10.4       |  | Addendum No. 3 to the Master Supply Agreement, effective as of April 1, 2011, by and between diaDexus, Inc. and Berkeley HeartLab, Inc.                                                                                                                                                                                                                                                         
|           | 
|10.5**     |  | Purchase Agreement, effective as of January 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                                                            
|           | 
|10.6**     |  | Volume Discount Addendum to the Purchase Agreement, effective as of January 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                            
|           | 
|10.7+      |  | Volume Discount Addendum No. 2 to the Purchase Agreement, effective as of April 1, 2011, by and between diaDexus, Inc. and Health Diagnostics Laboratory                                                                                                                                                                                                                                        
|           | 
|31.1       |  | Certification of Chief Executive Officer pursuant to Exchange Act Rule 13a-14(a)                                                                                                                                                                                                                                                                                                                
|           | 
|31.2       |  | Certification of Chief Financial Officer pursuant to Exchange Act Rule 13a-14(a)                                                                                                                                                                                                                                                                                                                
|           | 
|32.1+      |  | Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002                                                                                                                                                                                                                                               
|           | 
|32.2+      |  | Certification of Chief Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002                                                                                                                                                                                                                                               



|* | Certain schedules referenced in the Agreement and Plan of Merger and Reorganization have been omitted in accordance with Item 601(b)(2) of Regulation S-K. A copy
of any omitted schedule will be furnished supplementally to the Securities and Exchange Commission upon request.
|- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|** | Certain portions have been omitted pursuant to a confidential treatment request. Omitted information has been filed separately with the SEC.
|-- | --------------------------------------------------------------------------------------------------------------------------------------------

|+ | Filed with the Q1 Form 10-Q.
|- | ----------------------------