September 13, 2006
Confidential For Use of the Commission Only
Via EDGAR and Federal Express
Michael Pressman
Office of Mergers & Acquisitions
Securities and Exchange Commission
100 F St., NE
Washington, D.C. 20549
| RE: | Threshold Pharmaceuticals,, Inc. |
| Schedule TO-I filed August 25, 2006 |
| File No. 5-81377 |
Dear Mr. Pressman:
On behalf of Threshold Pharmaceuticals, Inc. (“Threshold”) and as requested by the staff of the Securities and Exchange Commission (the “Staff”) in a letter dated September 6, 2006 related to the filing of the above-referenced Schedule TO (the “Schedule TO”), Threshold hereby acknowledges the following:
| • | Threshold is responsible for the adequacy and accuracy of the disclosure in the filing; |
| • | Staff comments or changes to disclosure in response to staff comments in the filings reviewed by the Staff do not foreclose the Commission from taking any action with respect to the filing; and |
| • | Threshold may not assert staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States. |
We appreciate the efforts of the Staff to assist Threshold in connection with the above referenced filing.
| Sincerely, |
| /s/ Harold E. Selick |
| Harold E. Selick, Ph.D |
| Chief Executive Officer |