Ambit Announces Presentation of Results from Phase 2 ACE Study of Quizartinib in Patients with Relapsed or Refractory Acute

Ambit Announces Presentation of Results from Phase 2 ACE Study of Quizartinib
 in Patients with Relapsed or Refractory Acute Myeloid Leukemia (AML) at the
         Annual Meeting of the American Society of Clinical Oncology

Phase 3 Clinical Trial in FLT3-ITD Positive Relapsed/Refractory AML Patients
Planned for Early 2014

PR Newswire

CHICAGO, June 4, 2013

CHICAGO, June 4, 2013 /PRNewswire/ --Ambit Biosciences Corporation (Nasdaq:
AMBI) announced today that multiple presentations from the Phase 2 ACE study
of quizartinib (AC220), a FLT3 inhibitor, were presented at the Annual Meeting
of the American Society of Clinical Oncology.

Data presented included analyses of the 333 patients with relapsed or
refractory acute myeloid leukemia (AML) from a Phase 2 clinical trial of
quizartinib as monotherapy. In the study, quizartinib was administered orally,
once-a-day, in 28-day treatment cycles until disease progression, elective
hematopoietic stem cell transplantation (HSCT) or unacceptable toxicity. Based
on the positive data from the Phase 2 clinical trial, as well as ongoing
discussions with the Food and Drug Administration (FDA), Ambit is planning to
initiate a Phase 3 clinical trial in FLT3-ITD positive patients with relapsed
or refractory AML in early 2014.

Data Presentations

High Response Rate and Bridging to Hematopoietic Stem Cell Transplantation
with Quizartinib (AC220) in Patients with FLT3‑ITD Positive or Negative
Relapsed/Refractory AML after Second Line Chemotherapy or Previous Bone Marrow
Transplant (Abstract #7012)
Jorge Cortes, M.D., Division of Cancer Medicine, The University of Texas M. D.
Anderson Cancer Center, Houston, Texas

Data from 176 patients, aged 18 years or older, with either relapsed disease
or who were refractory to second-line chemotherapy or HSCT were presented. Of
the 136 FLT3 positive patients, 35 percent were successfully bridged to a
potentially curative HSCT, with the greatest proportion receiving a HSCT after
achieving a CRi (complete remission with incomplete hematologic recovery) with
quizartinib. Additionally, 33 percent of patients who were bridged to HCST
after achieving a CRi were still alive after one year, with multiple patients
alive after more than two years.

Additional key findings presented include:

  oForty-six percent of FLT3-ITD positive patients achieved a composite
    complete response (CRc: complete remission (CR) + complete remission with
    incomplete platelet recovery (CRp) + complete remission with incomplete
    hematologic recovery (CRi)), including five percent of patients who
    achieved either a CR or CRp
  oMedian overall survival for the 47 FLT3-ITD positive patients who achieved
    either a CRc or partial response (PR) to quizartinib and were bridged to a
    subsequent HSCT was 34.1 weeks, compared to 24.1 weeks for the 56 patients
    who achieved either a CRc or PR but did not undergo a subsequent HSCT,
    highlighting the positive impact of bridge to HSCT
  oMedian overall survival for the 33 FLT3-ITD positive patients who did not
    achieve at least a PR to quizartinib was 8.9 weeks, which reflects the
    limited therapeutic options these patients have in this setting and the
    importance of achieving a response to quizartinib given its positive
    impact on overall survival
  oTwenty percent (27/136) FLT3-ITD positive patients remained alive for more
    than 12 months and were classified as long-term survivors
  oAll but one of the long-term survivors achieved at least a PR to
    quizartinib, with 63 percent (17/27) proceeding to a HSCT after
    quizartinib
  oTen of the 27 long-term survivors did not undergo a subsequent HSCT and
    had a median treatment duration of 53.5 weeks
  oAdditionally, 30 percent of FLT3-ITD negative patients achieved a CRc,
    including six percent who achieved either a CR or CRp to quizartinib
    highlighting this as an area of continued clinical development for
    quizartinib
  oQuizartinib was generally well tolerated with manageable toxicity which
    included a grade 3 QTcF prolongation of 18 percent and no grade 4 QTcF
    prolongation events

Quizartinib (AC220) Produces High Response Rates and Long-Term Survival in
Elderly Patients With FLT3-ITD(+) or FLT3-ITD(–) Relapsed/Refractory Acute
Myeloid Leukemi
Giovanni Martinelli, M.D., Ph.D., Seragnoli Institute of Hematology,
University of Bologna School of Medicine, Bologna, Italy

Data presented included response rates and long-term survival in 154 patients,
aged 60 years or older, who had relapsed within one year or were refractory to
first-line therapy. Of the 110 FLT3-ITD positive patients, 57 percent achieved
a CRc, with seven percent having either a CR or CRp, with a median survival of
25.3 weeks. Additionally, 14 percent of patients remained alive for more than
12 months and were classified as long-term survivors which highlights the
clinical benefit of quizartinib given all patients in this analysis were 60
years of age or older, with nearly 50 percent refractory to their last therapy
and overall had a poor prognosis.

Additional key findings presented include:

  oOf the 104 FLT3-ITD positive patients who lived at least 28 days to be
    assessed for response (excludes six patients from the intent-to-treat
    population), the median overall survival for the 84 patients who achieved
    either a CRc or partial response (PR) to quizartinib is 31.1 weeks,
    compared to 11.8 weeks for the 20 patients who did not achieve at least a
    PR to quizartinib
  oOf the 14 percent (22/154) of patients who were long-term survivors, 95
    percent achieved either a CRc or PR to quizartinib, with 52.1 weeks as
    median duration of treatment for the 16/110 FLT3-ITD positive patients who
    were long-term survivors, which further highlights the long treatment
    duration in this patient population
  oAdditionally 36 percent of FLT3-ITD negative patients achieved a CRc, with
    seven percent achieving either a CR or CRp with quizartinib, and their
    median survival was 19.1 weeks
  oQuizartinib was generally well tolerated, with a 30-day mortality rate of
    six percent

Efficacy and Safety of Quizartinib (AC220) in Patients Aged ≥70 Years With
FLT3‑ITD(+) ^ or FLT3‑ITD(–) Relapsed/Refractory Acute Myeloid Leukemia
Alexander Perl, M.D., Division of Hematology/Oncology, University of
Pennsylvania, Philadelphia, Penn.

Data presented in 83 patients, aged 70 years or older, who had relapsed or
were refractory to their last therapy supported high response rates with
quizartinib similar to that seen in younger treated patient populations in the
study, despite the generally higher level of heterogeneity seen in elderly
patients with AML. Of the 60 FLT3-ITD positive patients, 53 percent achieved a
CRc, with 7 percent having either a CR or CRp. The median survival for these
patients was 21 weeks. Additionally, 14 percent (12/83) of patients remained
alive for more than 12 months, the majority of which (8/12) were FLT3-ITD
positive, and were classified as long-term survivors. The eight FLT3-ITD
positive long-term survivors all achieved at least a PR to quizartinib and
remained on treatment for a median of 53 weeks with survival ranging up to 93+
weeks.

Additional key findings presented include:

  oAdditionally 43 percent of FLT3-ITD negative patients achieved a CRc, with
    13 percent achieving either a CR or CRp with quizartinib, and had a median
    survival of 19 weeks
  oQuizartinib was generally well-tolerated, with a 30-day mortality rate of
    eight percent

About Quizartinib
Quizartinib (AC220) is a novel, potent, highly selective, orally bioavailable
FMS-like tyrosine kinase-3 (FLT3) inhibitor currently under evaluation in
multiple ongoing studies, which include a Phase 2b clinical trial as
monotherapy treatment for adult patients with FLT3-ITD positive relapsed or
refractory AML and two Phase 1 studies in a combination treatment regimen with
chemotherapy, and as a maintenance therapy following transplant, respectively.

On March 12, 2013, Ambit and Astellas Pharma, Inc., announced that their
collaboration for the joint development and commercialization of quizartinib
will terminate effective September 3, 2013, at which time Ambit will
exclusively own worldwide rights to quizartinib and any follow-on compounds.
The companies are working on the transition of the current development
activities to Ambit.

About Ambit Biosciences
Ambit is a biopharmaceutical company focused on the discovery, development and
commercialization of drugs to treat unmet medical needs in oncology,
autoimmune and inflammatory diseases by inhibiting kinases that are important
drivers for those diseases. Ambit's lead drug candidate, quizartinib (AC220),
is a once-daily, orally-administered potent and selective, inhibitor of
FMS-like tyrosine kinase-3 (FLT3) and is currently under clinical development
in patients with relapsed/refractory acute myeloid leukemia (AML) and in newly
diagnosed AML patients in combination with chemotherapy as well as maintenance
following a hematopoietic stem cell transplantation (HSCT). In addition to
quizartinib, Ambit's clinical pipeline includes AC410, an oral JAK2 inhibitor,
and CEP-32496, a BRAF inhibitor licensed to Teva Pharmaceutical Industries
Ltd. Ambit's preclinical portfolio includes a proprietary CSF1R inhibitor
program.

Forward-Looking Statements
Statements contained in this press release regarding matters that are not
historical facts are "forward-looking statements" within the meaning of the
Private Securities Litigation Reform Act of 1995, including statements
associated with Ambit's expectations regarding future development and
therapeutic potential of Ambit's lead drug candidate and other programs.
Because such statements are subject to risks and uncertainties, actual results
may differ materially from those expressed or implied by such forward-looking
statements. Words such as "believes," "anticipates," "plans," "expects,"
"intends," "will," "goal," "potential" and similar expressions are intended to
identify forward-looking statements. These forward-looking statements are
based upon Ambit's current expectations and involve assumptions that may never
materialize or may prove to be incorrect. Actual results and the timing of
events could differ materially from those anticipated in such forward-looking
statements as a result of various risks and uncertainties, which include,
without limitation, risks associated with the process of discovering,
developing and commercializing drugs that are safe and effective for use as
human therapeutics, and in the endeavor of building a business around such
drugs. These and other risks concerning Ambit's programs are described in
additional detail in Ambit's SEC filings. All forward-looking statements
contained in this press release speak only as of the date on which they were
made. Ambit undertakes no obligation to update such statements to reflect
events that occur or circumstances that exist after the date on which they
were made.

Contacts:

Ian Stone or David Schull (Media)
Russo Partners
(619) 308-6541
(212) 845-4271
ian.stone@russopartnersllc.com
david.schull@russopartnersllc.com

Robert Flamm, Ph.D. (Investor)
Russo Partners
(212) 845-4226
Robert.flamm@russopartnersllc.com

SOURCE Ambit Biosciences Corporation

Website: http://www.russopartnersllc.com