SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC  20549
 
SCHEDULE 13G/A
(Rule 13d-102)
 
INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b), (c), AND
(d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13D-2
( AMENDMENT NO.  4 )*

 
Threshold Pharmaceuticals, Inc.
(Name of Issuer)
 
Common Stock, $0.001 par value per share
(Title of Class of Securities)
 
885807206
(CUSIP Number)
 
August 29, 2008
(Date of Event Which Requires Filing of This Statement)
 
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
 
o           Rule 13d-1(b)
 
ý           Rule 13d-1(c)
 
o           Rule 13d-1(d)
 
*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.
 
The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).
 
Page 1 of 8 pages
 
CUSIP No.   885807206  
 
13G/A
Page 2 of 8 Pages
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

TANG CAPITAL PARTNERS, LP
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) o
(b) ý
3
SEC USE ONLY
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION

DELAWARE
NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH REPORTING
PERSON WITH
5
SOLE VOTING POWER
 
0
6
SHARED VOTING POWER
 
1,399,877
7
SOLE DISPOSITIVE POWER
 
0
8
SHARED DISPOSITIVE POWER
 
1,399,877
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,399,877
10
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

¨
11
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

 9.20%
12
TYPE OF REPORTING PERSON

PN

Page 2 of 8 pages
 
CUSIP No.    885807206 
 
13G/A
Page 3 of 8 Pages
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
TANG CAPITAL MANAGEMENT, LLC
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) o
(b) ý
3
SEC USE ONLY
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION

DELAWARE
NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH REPORTING
PERSON WITH
5
SOLE VOTING POWER
 
0
6
SHARED VOTING POWER
 
1,399,877
7
SOLE DISPOSITIVE POWER
 
0
8
SHARED DISPOSITIVE POWER
 
1,399,877
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,399,877
10
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

¨
11
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

 9.20%
12
TYPE OF REPORTING PERSON

OO
 

Page 3 of 8 pages
 
CUSIP No.   885807206
 
13G/A
Page 4 of 8 Pages
1
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
 
KEVIN C. TANG
 
2
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) o
(b) ý
3
SEC USE ONLY
 
4
CITIZENSHIP OR PLACE OF ORGANIZATION

UNITED STATES
NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH REPORTING
PERSON WITH
5
SOLE VOTING POWER
 
23,231
6
SHARED VOTING POWER
 
1,479,415
7
SOLE DISPOSITIVE POWER
 
23,231
8
SHARED DISPOSITIVE POWER
 
1,497,372
9
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
1,520,603
10
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

¨
11
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

 9.99%
12
TYPE OF REPORTING PERSON

IN

Page 4 of 8 pages
 
Item 1(a). Name of Issuer:
   
 
Threshold Pharmaceuticals, Inc., a Delaware corporation (the “Issuer”)
   
Item 1(b).  Address of Issuer’s Principal Executive Offices:
   
 
1300 Seaport Boulevard, Redwood City, California 94063
   
Item 2(a).    Name of Person Filing:
   
 
This Statement on Schedule 13G (this “Statement”) is filed by Tang Capital Partners, LP (“Tang Capital Partners”); Tang Capital Management, LLC, the general partner of Tang Capital Partners (“Tang Capital Management”); and Kevin C. Tang, the manager of Tang Capital Management.
   
Item 2(b).  Address of Principal Business Office or, if none, Residence:
   
  4401 Eastgate Mall, San Diego, CA 92121
   
Item 2(c).   Citizenship:
   
 
Tang Capital Partners is a Delaware limited partnership. Tang Capital Management is a Delaware limited liability company. Mr. Tang is a United States citizen.
   
Item 2(d).  Title of Class of Securities:
   
 
Common Stock, $0.001 par value per share (the “Common Stock”)
   
Item 2(e).
CUSIP Number:  885807206

Item 3.  Not applicable.
    
Item 4.  Ownership.
       
 
 (a) Amount Beneficially Owned:
       
    Tang Capital Partners.  Tang Capital Partners is the record and beneficial owner of 1,399,877 shares of Common Stock and shares voting and dispositive power over such securities with Tang Capital Management and Kevin C. Tang.
       
    Tang Capital Management. Tang Capital Management, as the general partner of Tang Capital Partners, may be deemed to beneficially own the 1,399,877 shares held of record by Tang Capital Partners and shares voting and dispositive power over such shares with Tang Capital Partners and Kevin C. Tang.
       
    Kevin C. Tang. Kevin C. Tang may be deemed to beneficially own 1,520,603 shares of the Issuer’s Common Stock, comprising:
       
   
 ●
1,399,877 shares owned of record by Tang Capital Partners, for which Tang Capital Management, of which Mr. Tang is manager, serves as general partner.  Mr. Tang shares voting and dispositive power over such shares with Tang Capital Management and Tang Capital Partners.
       
   
 ●
4,716 shares owned of record by Mr. Tang.
 
 
Page 5 of 8 pages
 
 
 ●
116,010  shares over which Mr. Tang has voting and/or dispositive power.
       
   
Mr. Tang disclaims beneficial ownership of all shares reported herein except to the extent of his pecuniary interest therein.
 
 
In addition to the foregoing shares, Tang Capital Partners holds a warrant to purchase 294,117 shares of the Issuer's Common Stock at an exercise price of $2.34 per share and an expiration date of August 29, 2013.
 
The above warrant provides that in no event shall the warrant be exercisable to the extent that the issuance of Common Stock upon exercise thereof, after taking into account the Common Stock then owned by Tang Capital Partners and its affiliates, would result in the beneficial ownership by Tang Capital Partners and its affiliates of more than 9.99% of the outstanding Common Stock (the "Issuance Limitation"). Tang Capital Partners has the express right to waive the Issuance Limitation upon sixty-one (61) days written notice to the Issuer. The Issuance Limitation presently remains in effect with respect to such warrant and no shares are currently issuable upon exercise of such warrant. Neither the filing of this Schedule 13G nor any of its contents shall be deemed to constitute an admission by Tang Capital Partners or any other person that it is the beneficial owner of any of the Common Stock underlying such warrant for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed.
 
 
 (b) Percent of Class:
     
    Tang Capital Partners   9.20%
    Tang Capital Management  9.20%
    Kevin C. Tang   9.99%
     
 
 (c) Number of shares as to which such person has:
     
    (i) sole power to vote or to direct the vote: 
         
      Tang Capital Partners 0 shares
      Tang Capital Management 0 shares
      Kevin C. Tang 23,231 shares
         
    (ii)  shared power to vote or to direct the vote: 
         
      Tang Capital Partners 1,399,877 shares
      Tang Capital Management   1,399,877 shares
      Kevin C. Tang  1,479,415 shares
         
    (iii)  sole power to dispose or to direct the disposition of: 
         
      Tang Capital Partners 0 shares
      Tang Capital Management 0 shares
      Kevin C. Tang 23,231 shares
         
    (iv) shared power to dispose or to direct the disposition of: 
         
      Tang Capital Partners 1,399,877 shares
      Tang Capital Management 1,399,877 shares
      Kevin C. Tang 1,497,372 shares
 
Page 6 of 8 pages
 
 Item 5.  Ownership of Five Percent or Less of a Class.
   
  If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following:  ¨
   
Item 6.  Ownership of More than Five Percent on Behalf of Another Person.
   
  Not applicable.
   
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company.
   
  Not applicable.
   
Item 8. Identification and Classification of Members of the Group.
   
  Not applicable.
   
Item 9. Notice of Dissolution of Group.
   
  Not applicable.
 
Item 10.  Certification.
   
 
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.
 
 
Page 7 of 8 pages
 
SIGNATURE
 
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
 

 Date:   September 8, 2008
   
   
TANG CAPITAL PARTNERS, LP
   
By:  Tang Capital Management, LLC, its General Partner
   
By:      /s/ Kevin C. Tang  
  Kevin C. Tang, Manager
   
  
TANG CAPITAL MANAGEMENT, LLC
   
By:     /s/ Kevin C. Tang 
  Kevin C. Tang, Manager
   
   
/s/ Kevin C. Tang 
Kevin C. Tang
 
 
 
Page 8 of 8 pages