On April 26, 2017 ArQule, Inc. (Nasdaq: ARQL) reported that the U.S. Patent and Trademark Office has issued U.S. Patent Number 9,630,968 (Press release, ArQule, APR 26, 2017, View Source [SID1234518690]). The patent claims composition of matter of ARQ 531. ArQule will be entitled to patent protection through December 2035 in the U.S. for the allowed claims. ARQ 531 is an investigational, orally bioavailable, potent and reversible inhibitor of both wild type and C481S-mutant Bruton’s tyrosine kinase (BTK). The company plans to begin a phase 1 clinical trial by the third quarter of 2017 with ARQ 531 in patients with B-cell malignancies who are refractory to other therapeutic options.

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"This patent secures long lasting and foundational intellectual protection for ARQ 531," said Peter Lawrence, President, Chief Operating Officer, and General Counsel at ArQule. "We continue to work to extend and strengthen all intellectual property related to chemical equity that has been generated through our multiple years of investment in the BTK discovery program."

B-cell malignancies, like chronic lymphocytic leukemia, Waldenstrom’s macroglobulinemia, diffuse large B-cell lymphoma and mantle cell lymphoma are driven by BTK. The only approved BTK inhibitor, ibrutinib, is irreversible and makes a covalent bond with the C481 residue of the targeted protein. Although ibrutinib has demonstrated excellent responses in patients with elevated B-cell receptor signaling, clinical resistance has been observed, and the BTK C481S mutation is emerging as a predominant mechanism of resistance. As a reversible inhibitor, ARQ 531 does not require interaction with the C481 residue, a binding site essential for irreversible ibrutinib binding to BTK, thus positioning ARQ 531 as a targeted therapy for patients harboring C481S-mutant BTK who have developed resistance to irreversible BTK inhibitors.

About BTK and ARQ 531

ARQ 531 is an investigational, orally bioavailable, potent and reversible Bruton’s tyrosine kinase (BTK) inhibitor. Biochemical and cellular studies have shown that ARQ 531 inhibits both the wild type and C481S-mutant forms of BTK. The C481S mutation is a known emerging resistance mechanism for first generation irreversible BTK inhibitors. In preclinical studies ARQ 531 has demonstrated high oral bioavailability as well as good ADME, pharmacokinetic and metabolic properties. The company plans to initiate a phase 1 trial by the third quarter of 2017. BTK is a therapeutic target that has been clinically proven to inhibit B-cell receptor signaling in blood cancers.