Ambit Biosciences Announces Presentation of Data from Clinical Investigations of Quizartinib at the 2014 Annual Meeting of The American Society Of Clinical Oncology

SAN DIEGO, June 3, 2014 /PRNewswire/ -- Ambit Biosciences (Nasdaq: AMBI), a biopharmaceutical company focused on discovery and development of drugs targeting unmet needs in oncology, autoimmune and inflammatory disease, today announced two poster presentations at the Annual Meeting of the American Society of Clinical Oncology, held May 30 through June 3, 2014, at McCormick Place in Chicago.

Final Results of a Randomized Phase 2 Study Showing the Clinical Benefit of quizartinib (AC220) in Patients with FLT3-ITD Positive Relapsed or Refractory Acute Myeloid Leukemia:  The objective of this study was to assess the efficacy and safety of lower doses (30mg/day and 60mg/day) of quizartinib in the treatment of subjects 18-years or older with relapsed/refractory FLT3-ITD positive AML.

A total of 76 subjects were enrolled from May 2012 to March 2013. This analysis includes additional follow up to the preliminary analysis presented at the 2013 Annual Meeting of the American Society of Hematology (ASH). Median age for all subjects was 55 (19-77) years, while 24% and 11% were older patients of at least 70 years of age in the 30mg/day and 60mg/day groups, respectively.

Of all patients included, 90% were FLT3-ITD(+). 24 (32%) subjects remained in follow-up at the time of the analysis, and are currently censored for overall survival. The following key information was presented:

• The CRc rate remained at 47 percent (5 percent CR+CRp, 42 percent CRi) given the majority of subjects had responded as of the last analysis
• The rate of hematopoietic stem cell transplantation (HSCT) after quizartinib use remained at 34 percent
• The median overall survival was 20.9 weeks for patients initially treated at 30mg/day and 25.4 weeks for patients at 60mg/day, with 24/38 patients censored as they remained alive in follow-up at the time of the analysis
• The additional follow-up improved the median overall survival for the 28 subjects who were bridged to a HSCT after quizartinib use to 34.1 weeks and 39.1 weeks (30mg/day and 60mg/day respectively)
• There was no change to the Grade 2 or greater QT prolongation which remained at 14% with a 4% Grade 3 rate and no Grade 4 events
• In addition, the further follow-up now shows 24 subjects were alive at >24 weeks with four subjects alive >12 months. Two of the four subjects were bridged to a HSCT immediately after quizartinib treatment, and one of the four subjects remains on study taking quizartinib for over one year
• Overall the additional follow-up continued to show that both the 30mg and the 60mg doses of quizartinib showed substantial activity in terms of overall CRc rate and bridge to HSCT with impact on improved median OS
• The safety profile is similar at both doses and QTcF prolongation did not worsen with additional duration of treatment and/or follow-up

The Benefit of Treatment with quizartinib and Subsequent Bridging to HSCT for FLT3-ITD(+) Patients with AML: This analysis focused on the combined data from our two Phase 2 Studies (AC220-002 Cohort 2 and the Phase 2b data highlighted above) to determine the activity of quizartinib monotherapy in subjects aged ≥18 years with FLT3-ITD(+) AML who are relapsed or have refractory disease after second line salvage therapy, or who relapsed after HSCT. Patients in these studies were not given quizartinib maintenance therapy after HSCT.

This analysis included a total of 212 subjects (136 subjects from Study AC220-002 Cohort 2) with an initial starting dose of quizartinib of 200 mg (n=12), 135 mg (n=67), and 90 mg (n=57).  Additionally, 76 subjects were randomized to a starting dose of quizartinib of 30 mg/day (n=38) or quizartinib 60 mg/day (n=38) from the Phase 2b Study. The following key information was presented:

• The majority (69%) of subjects in this analysis had relapsed disease with 29% having received a prior HSCT
• 34% of subjects were bridged to a HSCT after quizartinib use
• Despite the median baseline blast count of 81% for AC220-002 and 68% for the Phase 2b Study, 42-47% of subjects achieved a blast count of below 5% (CRc) with quizartinib
• The median overall survival across all five doses in these two studies ranged from 20.9 to 25.4 weeks. The largest improvement in median overall survival was in the 75 subjects who were bridged to a HSCT (34.1 weeks compared to 10.9 weeks in those who did not respond to quizartinib and were not bridged to a HSCT)
• 31/212 (15%) subjects remained alive for >12 months after taking quizartinib and 19/31 (61%) went to HSCT immediately after receiving quizartinib
• The most common cause of death after HSCT was AML progression (69%)
• Overall across the two Phase 2 studies, a high percentage of subjects achieved a CRc, were bridged to a HSCT, and an improvement in median overall survival was shown

The ongoing Phase 3 QUANTUM-R Study allows for quizartinib maintenance therapy after HSCT for subjects randomized to quizartinib initial treatment. Quizartinib maintenance therapy may decrease the relapse rate after HSCT and therefore increase median overall survival.

These ASCO poster presentations can be accessed on the Ambit Biosciences website at www.ambitbio.com.

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 in a registrational Phase 3 clinical trial, referred to as QUANTUM-R, in patients with relapsed/refractory FLT3-ITD positive, acute myeloid leukemia (AML). Quizartinib is also being studied in newly diagnosed 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 in this report that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding the presentation of data from clinical trials, the clinical benefits to be derived from quizartinib, and the future development and therapeutic potential of quizartinib and our other drug candidates. These forward-looking statements are based upon our 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 projected 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. For a discussion of these and other risks please refer to Ambit's Annual Report on Form 10-K for the year ended December 31, 2013 and Ambit's other periodic filings with the SEC. All forward-looking statements contained in this report speak only as of the date on which they were made. Ambit does not undertake any obligation to update forward-looking statements.

SOURCE Ambit Biosciences