On December 9, 2019 ArQule, Inc. (Nasdaq: ARQL) reported final results from the phase 1 study for ARQ 531, an orally bioavailable, potent and reversible dual inhibitor of both wild type and C481S-mutant Bruton’s tyrosine kinase (BTK) in patients with relapsed or refractory hematologic malignancies at the American Society of Hematology (ASH) (Free ASH Whitepaper) 2019 Annual Meeting & Exposition in Orlando, Florida (Press release, ArQule, DEC 9, 2019, View Source [SID1234552104]).
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"The final phase 1 data set confirms the potential utility of ARQ 531 for the treatment of these heavily pretreated CLL patients. We were excited to observe such deep and durable responses at a well-tolerated dose in this highly refractory population," commented Dr. Brian Schwartz, Chief Medical Officer of ArQule. "In addition, the three responses we observed in Richter’s Transformation patients were a welcome outcome and allowed several patients to transition to potentially curative therapies."
"ARQ 531 was selected and extensively tested preclinically to address the emerging therapeutic needs of patients who have become resistant to covalent BTK inhibitors in a broad set of hematologic malignancies," commented Dr. Jennifer Woyach, Associate Professor of Medicine at The Ohio State University and the Principal Investigator of the study. "It is tremendously gratifying to witness the emergence of a potential therapeutic for patients with such a high degree of unmet need, such as C481S-mutant CLL and Richter’s Transformation, and beyond. The data presented in this poster provide compelling proof-of-concept for this novel class of reversible BTK inhibitors."
The reported data are from the phase 1, open label, single arm dose escalation study and include patients (n=47) initially dosed at levels of 5, 10, 15, 20, 30, 45, 65 and 75 mg once a day with relapsed or refractory chronic lymphocytic leukemia (CLL), small lymphocytic leukemia (SLL), Richter’s Transformation, Waldenström macroglobulinemia and other B-cell Non-Hodgkin lymphomas.
Key Findings:
65 mg QD was selected as the Recommended Phase 2 Dose (RP2D) for further studies
Across all disease subsets, ARQ 531 showed a low incidence of associated toxicities, including one grade three DLT and no atrial fibrillation or bleeding observed
At 65 mg QD, ARQ 531 has a steady state mean Cmin above 1 µM and long plasma half-life of 56 hours resulting in complete pBTK inhibition
Clinical Anti-Tumor Activity:
In CLL, an Overall Response Rate (ORR) of 89% (8/9 responses in evaluable patients) was achieved in heavily pretreated R/R CLL patients (7/8 harboring BTK-C481S mutation) dosed at ≥65 mg QD. Eleven of 19 patients treated at 65 mg QD remain on study
In Richter’s Transformation, an ORR of 50% (3/6 responses in evaluable patients) was achieved at 65 mg QD
Two additional PRs were observed including one patient with Follicular Lymphoma (FL) and 1 patient with Diffuse Large B-cell Lymphoma (DLBCL)
Durability:
100% (5/5) evaluable CLL patients that received a third scan (cycle 9) are durable confirmed PRs and remain on therapy
67% (2/3) of Richter’s patients that achieved PRs came off study after becoming eligible for CAR-T therapy
The Follicular Lymphoma patient that achieved a PR has been on study for 120 weeks and remains a PR and on therapy
The poster at ASH (Free ASH Whitepaper) presenting these data entitled, "Final Results of Phase 1, Dose Escalation Study Evaluating ARQ 531 in Patients with Relapsed or Refractory B-Cell Lymphoid Malignancies," is available on the company’s website at www.arqule.com/publications-presentations/.
In addition, earlier today Merck and ArQule announced that the companies have entered into a definitive agreement under which Merck, through a subsidiary, will acquire ArQule. A copy of the joint press release is available on ArQule’s website, www.arqule.com.
ArQule will host a conference call and webcast for investors on Monday, December 9, 2019 at 8:15 a.m. EST to discuss the ARQ 531 clinical data. The live webcast can be accessed in the "Investors and Media" section of our website, www.arqule.com, under "Events & Presentations" or by visiting click here. You may also listen to the call by dialing (877) 868-1831 within the U.S. or (914) 495-8595 outside the U.S. and providing conference ID 4573858. A replay will be available two hours after the completion of the call and can be accessed in the "Investors & Media" section of our website, www.arqule.com, under "Events and Presentations."
ArQule management will host an Investor Event to answer questions and discuss these data in Orlando tonight, Monday, December 9, 2019 from 8:00–10:00 p.m. EST. Investors, sell side analysts, and industry representatives are welcome to attend. For event details and to RSVP, please email [email protected].
About BTK and ARQ 531
Bruton’s tyrosine kinase, BTK, is a therapeutic target that has been clinically proven to inhibit B-cell receptor signaling in blood cancers. ARQ 531 is an orally bioavailable, potent and reversible dual inhibitor of both wild type and C481S-mutant BTK. The C481S-mutation is a known resistance mechanism for first generation irreversible BTK inhibitors. ARQ 531 has demonstrated a manageable safety profile, predictable PK, convincing pharmacodynamic effects and signs of clinical activity.