OHSU and Aptose Present CG’806 Preclinical Data at ASH 59th Annual Meeting

CG’806 reveals broad and potent single agent activity, and enhanced activity when combined with Bcl-2 or BET inhibitors, against AML and CLL patient samples

PORTLAND, Ore. and SAN DIEGO, Dec. 11, 2017 (GLOBE NEWSWIRE) -- The OHSU Knight Cancer Institute and Aptose Biosciences Inc. (NASDAQ:APTO) (TSX:APS) today announced the presentation of preclinical data demonstrating that CG’806, a pan-FLT3/pan-BTK inhibitor, has broad and potent drug activity against acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and other hematologic disease subtypes. The data were highlighted in a poster presentation on Monday, December 11, 2017 at the American Society of Hematology (ASH) 59th Annual Meeting & Exposition, being held December 9-12 in Atlanta, GA.

The poster CG’806, a First-in-Class Pan-FLT3/BTK Inhibitor, Exhibits Potent Growth Inhibition as a Single Agent and in Combination with a BET Bromodomain Inhibitor and a Bcl2 Inhibitor Against AML and CLL Patient Samples, evaluated the activity of CG’806 on various hematologic malignancy cell lines and patient primary bone marrow specimens through the Beat AML Initiative. CG’806 exhibited broad and potent activity against primary patient samples over a diverse range of hematologic malignancy subtypes, including AML, CLL, myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN), and acute lymphoblastic leukemia (ALL).

The poster presentation can be accessed on the Events & Presentations section of the Aptose website at the following link.

“In patient samples and cultured cell lines, CG’806 demonstrated potent and broad inhibitory activity against hematologic malignancies alone and in combination,” said Stephen E. Kurtz, Ph.D., lead author and Research Assistant Professor at the OHSU Knight Cancer Institute. “Both AML and CLL are in urgent need of effective therapies that provide more durable clinical responses. CG’806 represents a potential new treatment approach that warrants further development.”

OHSU researchers used an ex vivo drug sensitivity assay to determine the activity of CG’806 as a single agent and in combination with the BET bromodomain inhibitor OTX-015 or the Bcl2 inhibitor venetoclax on freshly isolated primary patient samples. Across the four general subtypes of hematologic malignancies in the dataset with patient samples, there was broad sensitivity to CG’806, with 55% (90/164) AML, 48% (46/96) CLL, 22% (6/27) ALL, and 53% (14/26) MDS/MPN cases exhibiting an IC50 < 100nM. CG’806 demonstrated median IC50 values of 70nM and 140nM against primary AML and CLL cells, respectively. CG’806 also exerted potent picomolar to low-nanomolar IC50 anti-proliferative activity against human AML, B-ALL, mantle-cell lymphoma, Burkitt’s lymphoma, and diffuse large B-cell lymphoma cell lines. CG’806 in combination with OTX-015 demonstrated median IC50 values of 20nM and 40nM against primary AML and CLL cells, respectively. CG’806 in combination with venetoclax demonstrated median IC50 values of 20nM and 10nM against primary AML and CLL cells, respectively.

"Collaborating with OHSU and the Beat AML initiative has provided us an exceptional opportunity to explore the activity of CG‘806 against a large and diverse set of freshly isolated patient bone marrow samples from patients with AML, CLL and other hematologic malignancies,” commented William G. Rice, Ph.D., Chairman and Chief Executive Officer of Aptose. “CG’806 continues to reveal compelling preclinical results that are superior to other FLT3 or BTK inhibitors, and we are eagerly preparing CG’806 for clinical studies and look forward to an IND submission in 2018.”

Separately, Aptose and The University of Texas MD Anderson Cancer Center researchers also presented new data on CG’806 at ASH (see press release here). 

In addition to the abstracts that were presented at ASH, two additional abstracts on CG’806 and two abstracts on APTO-253, Aptose’s small molecule c-Myc Inhibitor, have been published on the ASH abstracts site.  All abstracts will become part of the permanent ASH and Blood abstracts archive.

For more information on Beat AML refer to https://www.lls.org/content/what-is-beat-aml.

About CG’806

CG‘806 is an oral, first-in-class pan-FLT3/pan-BTK inhibitor. This small molecule demonstrates potent inhibition of all wild type and mutant forms of FLT3 tested (including internal tandem duplication, or ITD, and mutations of the receptor tyrosine kinase domain and gatekeeper region), eliminates AML tumors in the absence of toxicity in murine xenograft models, and represents a potential best-in-class therapeutic for patients with FLT3-driven AML. Likewise, CG’806 demonstrates potent, non-covalent inhibition of the wild type and Cys481Ser mutant forms of the BTK enzyme, as well as other oncogenic kinases operative in B cell malignancies, suggesting CG’806 may be developed for CLL and MCL patients that are resistant/refractory/intolerant to covalent BTK inhibitors.

About Aptose

Aptose Biosciences is a clinical-stage biotechnology company committed to developing personalized therapies addressing unmet medical needs in oncology. Aptose is advancing new therapeutics focused on novel cellular targets on the leading edge of cancer. The company's small molecule cancer therapeutics pipeline includes products designed to provide single agent efficacy and to enhance the efficacy of other anti-cancer therapies and regimens without overlapping toxicities. For further information, please visit www.aptose.com.

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For further information, please contact:

Aptose Biosciences
Greg Chow, CFO
Email: gchow@aptose.com

OHSU | Oregon Health & Science University
Amanda Gibbs, Senior Media Relations Specialist, Knight Cancer Institute
Media Dept: 503-494-8231
Email: gibbam@ohsu.edu

SMP Communications
Susan Pietropaolo
Email: susan@smpcommunications.com

LifeSci Advisors
Michael Wood
Managing Director
Email: mwood@lifesciadvisors.com

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Source: Aptose Biosciences, Inc.