ArQule, Inc. announced the publication of the abstract highlighting data, as of July 19, 2019, from the phase 1 trial of ARQ 531, the company's potent and reversible dual inhibitor of both wild type and C481-mutant Bruton's tyrosine kinase (BTK), in patients with relapsed or refractory B-cell malignancies on the American Society of Hematology (ASH) website. A poster containing the final data set from the phase 1 portion of this study will be presented at the ASH annual meeting in Orlando, FL on December 9, 2019 and will detail additional data with respect to ARQ 531's safety profile, clinical activity and durability across multiple refractory B-Cell malignancies, including C481-mutant chronic lymphocytic leukemia (CLL). Dr. Brian Schwartz, Chief Medical Officer of ArQule, commented, "ARQ 531 continues to demonstrate profound effects at well-tolerated doses in a highly refractory patient population. Data on clinical activity, in CLL in particular, has improved further since the company's last presentation at EHA in June, and I'm looking forward to presenting important durability data for these patients at ASH. In addition, the unique kinase inhibition profile and favorable molecular properties of ARQ 531 are proving to be valuable in other, hard-to-treat B-cell malignancies, such as Richter's Transformation." The reported data are from the ongoing phase 1, open label, single arm dose escalation 3+3 study and include data from the first eight cohorts (n=40) at dose levels of 5, 10, 15, 20, 30, 45, 65 and 75 mg once a day in patients with relapsed or refractory (R/R) CLL, small lymphocytic leukemia (SLL), Richter's Transformation and other B-cell Non-Hodgkin lymphomas. Key findings of the abstract include: ARQ 531 continues to be well-tolerated through 65 mg QD and has a manageable safety profile in multiple B-cell malignancies; Pharmacokinetic (PK) data show that patients receiving 65 mg QD of ARQ 531 exhibited steady-state mean Cmin of above 1 uM, with complete pBTK inhibition; Robust, dose-dependent, anti-tumor activity was observed, including 10 PRs, especially at the higher doses; Of the 6 evaluable patients recruited in cohort 7 with R/R CLL/SLL and dosed initially at 65 mg QD, 5 experienced a PR as of July 19, 2019; Two additional R/R CLL patients experienced a PR: 1 patient dose escalated from 45 to 65 mg QD and another de-escalated from 75 to 65 mg QD; Three additional PRs were observed outside of CLL including 1 patient with Follicular Lymphoma, 1 with Richter's Transformation and 1 with Diffuse Large B-Cell Lymphoma.