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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>UNITED STATES<BR>
SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Washington, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>FORM 8-K</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>CURRENT REPORT</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Pursuant to Section 13 or 15(d) of the
</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Securities Exchange Act of 1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Date of Report (Date of earliest event reported):
September 17, 2012</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 18pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>THRESHOLD PHARMACEUTICALS, INC.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(Exact name of registrant as specified
in its charter)</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 33%; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; font-weight: bold; text-align: center">Delaware</TD>
    <TD STYLE="width: 34%; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; font-weight: bold; text-align: center">001&#45;32979</TD>
    <TD STYLE="width: 33%; padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; font-weight: bold; text-align: center">94&#45;3409596</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 4.5pt; text-align: center"><B>(State or other jurisdiction</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>of incorporation)</B></P></TD>
    <TD STYLE="padding-right: 5.4pt; padding-left: 5.4pt; font-size: 10pt; font-weight: bold; text-align: center">(Commission File Number)</TD>
    <TD STYLE="padding-right: 5.4pt; padding-left: 5.4pt">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(IRS Employer</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Identification No.)</B></P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1.25in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>170 Harbor Way, Suite 300<BR>
South San Francisco, California 94080</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(Address of principal executive offices)(Zip
Code)</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 63pt; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(650) 474-8200</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(Registrant&rsquo;s telephone number,
including area code)</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check the appropriate box below if the Form 8-K filing is intended
to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings">o</FONT> Written communications
pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings">o</FONT> Soliciting material
pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings">o</FONT> Pre-commencement
communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings">o</FONT> Pre-commencement
communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<TD STYLE="width: 0in"></TD><TD STYLE="width: 1in; text-align: left"><B>Item 8.01</B></TD><TD><B>Other Events.</B></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">On September 17, 2012, Threshold Pharmaceuticals, Inc. issued
a press release announcing that data from a randomized open-label Phase 2b clinical trial of investigational hypoxia-targeted drug
TH-302 in patients with advanced pancreatic cancer will be presented at the European Society for Medical Oncology (ESMO) 2012 Congress
in Vienna taking place September 28 &ndash; October 2, 2012.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The Company also announced <FONT STYLE="color: black">new findings
of overall survival results, a secondary endpoint, </FONT>of the Phase 2b clinical trial <FONT STYLE="color: black">evaluating
the efficacy and safety of two doses of TH-302 in combination with gemcitabine compared to gemcitabine alone in patients with advanced
pancreatic cancer.</FONT> The press release is attached as Exhibit 99.1 to this Form 8-K.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 24.5pt">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0in"></TD><TD STYLE="width: 1in; text-align: left"><B>Item 9.01</B></TD><TD><B>Financial Statements and Exhibits.</B></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<TD STYLE="width: 0.5in"></TD><TD STYLE="width: 0.5in; text-align: left">(d)</TD><TD>Exhibits</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 1in"></TD><TD STYLE="width: 1in; text-align: left">Exhibit 99.1</TD><TD>Press release dated September 17, 2012.</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">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
thereunto duly authorized.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

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<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2"><B>THRESHOLD PHARMACEUTICALS, INC.</B></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD COLSPAN="2">&nbsp;</TD></TR>
<TR>
    <TD STYLE="vertical-align: top; width: 50%">&nbsp;</TD>
    <TD STYLE="width: 4%">By:&nbsp;</TD>
    <TD STYLE="vertical-align: top; width: 46%">/s/ <FONT STYLE="font-variant: small-caps">Joel A. Fernandes</FONT></TD></TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; border-top: #000000 1px solid">Joel A. Fernandes<BR>Vice President, Finance and Controller</TD></TR>
</TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; text-align: left; text-indent: 0pt; margin-top: 0pt; margin-bottom: 6pt">Date: September 17, 2012</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Exhibit Index</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0in"></TD><TD STYLE="width: 1.5in; text-align: left"><U>Exhibit No.</U></TD><TD><U>Description</U></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.85in 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0pt"><TR STYLE="vertical-align: top">
<TD STYLE="width: 0in"></TD><TD STYLE="width: 1.5in; text-align: left">Exhibit 99.1</TD><TD>Press release dated September 17, 2012.</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934
Date of Report (Date of earliest event reported):
September 17, 2012
THRESHOLD PHARMACEUTICALS, INC.
(Exact name of registrant as specified
in its charter)
Delaware
001-32979
94-3409596
(State or other jurisdiction
of incorporation)
(Commission File Number)
(IRS Employer
Identification No.)
170 Harbor Way, Suite 300
South San Francisco, California 94080
(Address of principal executive offices)(Zip
Code)
(650) 474-8200
(Registrant's telephone number,
including area code)
Check the appropriate box below if the Form 8-K filing is intended
to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
o
Written communications
pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
o
Soliciting material
pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
o
Pre-commencement
communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
o
Pre-commencement
communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Item 8.01
Other Events.
On September 17, 2012, Threshold Pharmaceuticals, Inc. issued
a press release announcing that data from a randomized open-label Phase 2b clinical trial of investigational hypoxia-targeted drug
TH-302 in patients with advanced pancreatic cancer will be presented at the European Society for Medical Oncology (ESMO) 2012 Congress
in Vienna taking place September 28 – October 2, 2012.
The Company also announced
new findings
of overall survival results, a secondary endpoint,
of the Phase 2b clinical trial
evaluating
the efficacy and safety of two doses of TH-302 in combination with gemcitabine compared to gemcitabine alone in patients with advanced
pancreatic cancer.
The press release is attached as Exhibit 99.1 to this Form 8-K.
Item 9.01
Financial Statements and Exhibits.
(d)
Exhibits
Exhibit 99.1
Press release dated September 17, 2012.
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
thereunto duly authorized.
THRESHOLD PHARMACEUTICALS, INC.
By:
/s/
Joel A. Fernandes
Joel A. Fernandes
Vice President, Finance and Controller
Date: September 17, 2012
Exhibit Index
Exhibit No.
Description
Exhibit 99.1
Press release dated September 17, 2012.