Threshold Pharmaceuticals Announces Data From Two Ongoing Phase 1/2 Trials of TH-302 at the 2013 ASCO Annual Meeting

Threshold Pharmaceuticals Announces Data From Two Ongoing Phase 1/2 Trials of 
TH-302 at the 2013 ASCO Annual Meeting 
Responses Observed in Patients With Refractory Multiple Myeloma
Treated With TH-302 Plus Dexamethasone; Responses Observed in
Patients With Renal Cell Carcinoma and Gastrointestinal Stromal
Tumors Treated With TH-302 Plus Sunitinib 
SOUTH SAN FRANCISCO, CA -- (Marketwired) -- 06/02/13 --  Threshold
Pharmaceuticals, Inc. (NASDAQ: THLD) today announced data from two
ongoing Phase 1/2 trials evaluating TH-302, an investigational
hypoxia-targeted drug, at the 49th Annual Meeting of the American
Society of Clinical Oncology (ASCO), which is being held in Chicago,
Ill., May 31 through June 4. Updated results from a Phase 1/2 study
of TH-302 plus dexamethasone in patients with relapsed/refractory
multiple myeloma were presented supplementing the data published in
the meeting abstract (Abstract #8602). Of 12 evaluable patients, 2
achieved partial responses (PRs) and 2 minimal responses (MRs) for a
clinical benefit rate (MR or better) of 33%. In a Phase 1/2 clinical
trial of TH-302 administered in combination with the antiangiogenic
therapy sunitinib, one of 4 patients with gastrointestinal stromal
tumors (GIST) achieved a confirmed PR, and 3 of 4 patients with renal
cell carcinoma (RCC) achieved PRs. Data from this study were
published in an abstract included online in the ASCO 2013 Annual
Meeting Proceedings (Abstract # e15557).  
"These two studies expand our clinical experience with TH-302 and are
consistent with our prior investigations in both hematological
malignancies as well as in combination with antiangiogenic
therapies," said Tillman Pearce, M.D., Chief Medical Officer of
Threshold. "These encouraging data further support our ultimate goal
in developing TH-302 in a wide range of cancers where there is
currently an unmet medical need."  
Phase 1/2 Study of TH-302 in Patients with Relapsed/Refractory
Multiple Myeloma 
 As presented at the ASCO annual meeting, a total
of 13 patients with relapsed/refractory multiple myeloma and a median
number of 6 prior therapies initiated treatment with TH-302 plus
dexamethasone in an ongoing Phase 1/2 trial. All patients had
received prior therapy with regimens containing a proteasome
inhibitor, an immunomodulatory drug (IMiD), and an alkylating agent.
TH-302 was dosed at 240 mg/m2 (n=5), 340 mg/m2 (n=6), and 480 mg/m2
(n=2) for a median of 5 cycles. TH-302 was administered with
dexamethasone (fixed oral 40 mg dose) on days 1, 4, 8, and 11 of a
21-day cycle.  
Data from twelve efficacy evaluable patients were presented: 2
achieved partial responses (PRs), 2 achieved minimal responses (MRs),
and 8 achieved stable disease (SD), representing a clinical benefit
rate (MR or better) of 33%. No dose-limiting toxicity was reported in
the first two dose groups. Two patients treated at 480 mg/m2 TH-302
plus dexamethasone had dose limiting toxicities of grade 3
stomatitis. The maximum tolerated dose of TH-302 was established at
340 mg/m2; dose expansion is ongoing at this dose. 
"While IMiDs and proteasome inhibitors have changed the treatment
paradigm for myeloma over the past decade, the future of myeloma
therapy will depend on development of new therapeutic classes with
novel biological activities," said Irene Ghobrial, M.D., Associate
Professor of Medicine at Dana-Farber Cancer Institute, and Principle
Investigator of the Phase 1/2 study. "TH-302 is designed to
selectively target hypoxia, a condition that has been associated with
diseased bone marrows in models of myeloma. Targeting hypoxia may
offer a new approach to treating patients with multiple myeloma.
Though the data are limited, we are encouraged by these early signals
of TH-302 activity, which support further evaluation of TH-302 in
Phase 1/2 Study of TH-302 and Sunitinib in Patients with RCC, GIST,
and PNET
 As published online in the ASCO 2013 Annual Meeting
Proceedings, a total of 6 patients with RCC and 4 patients with GIST
initiated treatment with TH-302 plus sunitinib in an ongoing Phase
1/2 study, which is also enrolling patients with pancreatic
neuroendocrine tumors (PNET). Standard full dose sunitinib (50 mg)
was administered daily from day 1 to day 28 of a 6-week cycle. TH-302
(240 mg/m2 and 340 mg/m2) was administered on days 8, 15 and 22.
Patients had received a median number of 3 prior chemotherapies
including prior sunitinib in 7 patients. One of 4 patients with GIST
achieved a confirmed PR and 3 of 4 patients with RCC achieved PRs
including 2 with confirmed PRs. No dose limiting toxicities were
observed in the 3 patients in the 240 mg/m2 dose group; 1 patient of
5 evaluable in the 340 mg/m2 dose group experienced a dose limiting
toxicity of stomatitis.  
"It is thought that by shutting down tumor vasculature,
antiangiogenic therapies may increase tumor hypoxia and thus enhance
the target for TH-302," said Alexander Starodub, M.D., Ph.D., Medical
Oncologist at Indiana University Health Goshen Center for Cancer
Care, and Principle Investigator of the Phase 1/2 study. "Though the
data are limited, we are encouraged to see responses even in patients
who had received prior antiangiogenic therapy with sunitinib and
believe further evaluation is warranted in patients with RCC, GIST
and PNET." 
About TH-302
 TH-302 is an investigational hypoxia-targeted drug that
is designed to be activated under severe tumor hypoxic conditions, a
hallmark of many cancers. Areas of low oxygen levels (hypoxia) in
solid tumors are due to insufficient blood supply as a result of
aberrant vasculature. Similarly, the bone marrow of patients with
hematological malignancies has also been shown, in some cases, to be
severely hypoxic. 
TH-302 is currently under evaluation in two Phase 3 trials: one in
combination with doxorubicin versus doxorubicin alone in patients
with soft tissue sarcoma (STS), and the other in combination with
gemcitabine versus gemcitabine and placebo in patients with advanced
pancreatic cancer. Both Phase 3 trials are being conducted under a
Special Protocol Assessment agreement with the U.S. Food and Drug
Administration (FDA). The FDA and the European Commission have
granted TH-302 Orphan Drug Designation for the treatment of STS.
TH-302 is also being investigated in hematological malignancies and
other combination trials in solid tumors. 
Merck KGaA signed a global license and co-development agreement for
TH-302 with Threshold in February 2012, which includes an option for
Threshold to co-commercialize in the U.S. 
About Threshold Pharmaceuticals 
 Threshold Pharmaceuticals, Inc. is
a biotechnology company focused on the discovery and development of
drugs targeting tumor hypoxia, the low oxygen condition found in
microenvironments of most solid tumors as well as the bone marrows of
some hematologic malignancies. This approach offers broad potential
to treat a variety of cancers. By selectively targeting tumor cells,
we are building a pipeline of drugs that hold promise to be more
effective and less toxic to healthy tissues than conventional
anticancer drugs. For additional information, please visit our
website ( 
Forward-Looking Statements
 Except for statements of historical fact,
the statements in this press release are forward-looking statements,
including statements regarding the potential therapeutic uses and
benefits of TH-302 to treat patients with cancer. These statements
involve risks and uncertainties that can cause actual results to
differ materially from those in such forward-looking statements.
Potential risks and uncertainties include, but are not limited to,
Threshold's ability to enroll or complete its anticipated clinical
trials, the time and expense required to conduct such clinical trials
and analyze data, whether later trials confirm the results of earlier
trials, issues arising in the regulatory or manufacturing process and
the results of such clinical trials (including product safety issues
and efficacy results), and actions of regulatory authorities,
including the United States Food and Drug Administration. Further
information regarding risks faced by Threshold is included under the
heading "Risk Factors" in Threshold's Quarterly Report on Form 10-Q,
which has been filed with the Securities and Exchange Commission on
May 2, 2013 and is available from the SEC's website ( and
on our website ( under the heading
"Investors." We undertake no duty to update any forward-looking
statement made in this news release. 
Laura Hansen, Ph.D.
Senior Director, Corporate Communications
Phone: 650-703-6523
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