MEI Pharma announced that the Phase 1b trial arm exploring zandelisib, an investigational selective phosphatidylinositol 3-kinase (PI3K) delta inhibitor, in combination with zanubrutinib (marketed as BRUKINSA?), an inhibitor of Bruton's tyrosine kinase (BTK) developed by BeiGene, Ltd. (BeiGene), completed the safety evaluation stage in patients with B-cell malignancies and is expanding into disease specific B-cell malignancy cohorts. The Safety Review Committee recommended moving forward with a dosing regimen found to be generally well tolerated and active following a planned safety analysis.

"Inhibition of the PI3K and BTK pathways with combination therapy is believed to present a promising opportunity for inducing a robust and durable response against various B-cell malignancies," said Richard Ghalie, M.D., senior vice president, clinical development, of MEI Pharma. "The intermittent dosing schedule and unique therapeutic profile of zandelisib makes it an attractive option for combination therapy. We are encouraged that the data to date supported the recommendation of the Safety Review Committee to move forward with the expansion cohorts, initially in follicular and mantle cell lymphomas, and we look forward to further exploring the potential of this and other combinations of zandelisib in patients with various B-cell malignancies with our global development partner, Kyowa Kirin."