Oncternal Therapeutics has started the CIRLL study, a Phase Ib/II clinical trial of cirmtuzumab and ibrutinib combination for the treatment of patients with B-cell malignancies, including mantle cell lymphoma (MCL) and chronic lymphocytic leukaemia (CLL)/small lymphocytic leukaemia (SLL).

The multi-centre trial aims to enrol altogether 117 patients who were previously treated for MCL or CLL/SLL and who have not received previous Bruton’s tyrosine kinase (BTK) inhibitor therapy.

The initial dose-finding portion of the trial aims to determine the optimal dose of cirmtuzumab to administer when given with the approved dose of ibrutinib, and then confirm this dose in an expansion cohort.

The trial will then randomise patients to receive the combination of cirmtuzumab plus ibrutinib, or ibrutinib alone.

“Cirmtuzumab and ibrutinib synergistically block multiple signaling pathways that are important in the pathogenesis and progression of B-cell lymphomas and leukaemias.”

It aims to demonstrate that a significantly greater number of patients will achieve a durable complete response when treated with the combination compared to those treated with ibrutinib alone.

Oncternal is carrying out the CIRLL trial in collaboration with researchers at the University of California San Diego (UC San Diego) School of Medicine and the California Institute for Regenerative Medicine (CIRM) in the US.

Oncternal Therapeutics president and CEO James Breitmeyer said: “There remains significant unmet medical need for patients with B-cell malignancies because current drug treatments can induce partial responses, but these are temporary.

“Our collaboration with Dr Thomas Kipps of UC San Diego has shown that cirmtuzumab and ibrutinib synergistically block multiple signalling pathways that are important in the pathogenesis and progression of B-cell lymphomas and leukaemias and provide a strong rationale for combination therapy.”

Oncternal has included MD Anderson Cancer Center in Houston, as well as Columbia University Medical Center and Northwell Health, both in New York, US, to carry out the CIRLL study.

MD Anderson Cancer Center has already dosed the first mantle cell lymphoma patient of the trial.