On April 16, 2018 Oregon Health & Science University (OHSU) Knight Cancer Institute and Aptose Biosciences Inc. (NASDAQ:APTO) (TSX:APS) reported the presentation of preclinical data demonstrating that CG’806, a highly potent pan-FLT3/pan-BTK inhibitor, kills malignant cells in samples from patients with various hematologic malignancies and demonstrates superiority to other kinase inhibitors (Press release, Aptose Biosciences, APR 16, 2018, View Source c=116148&p=RssLanding&cat=news&id=2342649 [SID1234525328]). The data were presented in a poster on Sunday, April 15, at the 2018 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Conference being held April 14-18, in Chicago, IL.
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The poster, entitled CG’806, a first-in-class pan-FLT3/pan-BTK inhibitor, demonstrates superiority to other FLT3 and BTK inhibitors against primary patient samples, demonstrated the broad activity of CG’806 against primary bone marrow specimens from patients with various hematologic malignancies. CG’806 is a small molecule that potently inhibits wild type (WT) FLT3, as well as FLT3 housing the ITD mutation or with point mutations in the tyrosine kinase domain (TKD, including D835G, D835Y, D835H) or in the gatekeeper region (F691L); it also inhibits BTK WT and BTK-C481S. As part of the Beat AML Initiative, researchers at OHSU tested CG’806 against freshly isolated primary samples from patients with acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and other hematologic malignancies to determine its potency and range of action. Against AML patient samples, CG’806 was evaluated relative to other FLT3 inhibitors. In parallel, CG’806 and ibrutinib, a covalent BTK inhibitor approved for CLL and certain other B-cell malignancies, were compared directly for sensitivities on primary CLL samples and various B-cell and other hematologic malignancies. CG’806 was shown to have greater potency against a broader subset of AML samples relative to other FLT3 inhibitors, including midostaurin, gilteritinib, quizartinib, sorafenib, crenolanib, and dovitinib. This was especially true in FLT3-ITD and FLT3-TKD positive cases, although enhanced activity was also observed in FLT3 WT samples. CG’806 was also shown to have greater potency and range of activity on primary CLL samples than ibrutinib.
"The clinical benefit of current FLT3 inhibitors in AML is transient, as resistance develops after several months of treatment," said Stephen E. Kurtz, Ph.D., lead author and Research Assistant Professor at the OHSU Knight Cancer Institute. "Similarly, ibrutinib, a covalent BTK inhibitor approved for CLL and certain other B-cell malignancies, is limited by acquired resistance, as well as refractory disease and tolerance challenges. As a pan-FLT3/pan-BTK inhibitor – especially in the absence of observed toxicity in murine AML models – CG’806 offers important potential to address these limitations."
"CG’806 appears superior to other FLT3 and BTK inhibitors, and the wealth of data supporting its development in AML and B-cell malignancies continues to grow," said William G. Rice, Ph.D., Chairman and Chief Executive Officer of Aptose. "These studies are critical for understanding how to develop and position CG’806 as we prepare for clinical development in these challenging hematologic malignancies."
Separately, Aptose researchers also announced new data on CG’806 presented at AACR (Free AACR Whitepaper) (see press release here). Both poster presentations will be published in the AACR (Free AACR Whitepaper) Conference Proceedings. The posters can also be accessed here or at the Publications & Presentations section of the Aptose website, www.aptose.com.
For more information on Beat AML refer to View Source
About CG’806
CG‘806 is an oral, first-in-class pan-FLT3/pan-BTK multi-kinase inhibitor. This small molecule demonstrates potent inhibition of wild type and mutant forms of FLT3 (including internal tandem duplication, or ITD, and mutations of the receptor tyrosine kinase domain and gatekeeper region), eliminates acute myeloid leukemia (AML) tumors in the absence of toxicity in murine xenograft models, and represents a potential best-in-class therapeutic for patients with 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 kinase pathways operative in B cell malignancies, suggesting CG’806 may be developed for various B cell malignancy patients (including CLL, MCL, DLBCL and others) that are resistant/refractory/intolerant to covalent BTK inhibitors. CG’806 is currently in preclinical development in partnership with CrystalGenomics