The small-cap biotech announced preliminary results from a Phase 1 dose escalation study for ARQ 531 in patients with relapsed or refractory hematologic malignancies that showed the candidate was well-tolerated in a 65 mg once-daily dose.
ARQ 531 is an orally bioavailable reversible dual inhibitor of both wild type and C481S-mutant Bruton's tyrosine kinase, or BTK.
The data comes from an ongoing Phase 1 study that included eight cohorts at dose levels of 5, 10, 15, 20, 30, 45, 65 and 75 mg once-daily in patients with relapsed or refractory chronic lymphocytic leukemia, or CLL; small lymphocytic leukemia, or SLL; Richter's Transformation; Waldenstrom macroglobulinemia and other B-cell non-Hodgkin lymphomas.
The study showed that ARQ 531 is tolerated through 65 mg once-daily doses, and pharmacokinetic data demonstrated a steady-state mean Cmin of above 1 µM in patients receiving doses higher than 45 mg, with the plasma half-life at 20-30 hours.
Doses above 20-30 mg lead to complete pBTK inhibition and substantial CCL3 suppression, according to ArQule.
The study also showed dose-dependent anti-tumor activity, with an overall response rate of 66% in heavily pre-treated CLL patients from cohort 7 who have the BTK-C481S mutation.
"The data presented in this poster provide compelling clinical proof-of-concept for this novel class of reversible BTK inhibitors," Jennifer Woyach, the lead study investigator, said in a statement.
The data was presented as a poster at the 2019 European Hematology Association annual meeting in Amsterdam, the Netherlands.
ArQule said it will look ahead to finalize the recommended Phase 2 dose and advance ARQ 531 into later-stage trials across multiple indications as a single agent and as a combination therapy.
The stock was rising by 37.2% to $8.63 at the time of publication Friday.
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