MEI Pharma Reports Update from Clinical Study Evaluating Oral CDK9 Inhibitor Voruciclib in Combination with Venetoclax in Patients with Relapsed and Refractory Acute Myeloid Leukemia

MEI Pharma, Inc. (Nasdaq: MEIP), a clinical-stage pharmaceutical company evaluating novel drug candidates to address known resistance mechanisms to standard-of-care cancer therapies, today reported initiation of enrollment in a 12-patient expansion cohort in the ongoing Phase 1 study evaluating voruciclib, an investigational selective oral cyclin-dependent kinase 9 (“CDK9”) inhibitor, in combination with venetoclax (Venclexta), a B-cell lymphoma 2 (“BCL2”) inhibitor, in relapsed and refractory (“R/R”) acute myeloid leukemia (“AML”) patients. The Safety Review Committee recommended initiating the expansion cohort after observing anti-leukemic activity in multiple heavily pretreated patients in the dose escalation cohorts, including responses, anticipated decreases in myeloid leukemia cell differentiation protein (“Mcl-1”) in available patient samples, no overlapping toxicity or dose limiting toxicities, and favorable safety results to date.

“MCL-1 overexpression has been associated with a poor prognosis and development of resistance to BCL-2 inhibition by venetoclax in patients with AML and CLL. Voruciclib is a potent, oral CDK9 inhibitor that indirectly also suppresses MCL-1. We are participating in the ongoing multicenter phase 1 study, where preliminary results are demonstrating good treatment tolerance and safety to date,” said Yesid Alvarado-Valero, M.D., Associate Professor, Department of Leukemia, University of Texas MD Anderson Cancer Center and study chair of the combination therapy stage of the Phase 1 study. “When Voruciclib is used in combination with venetoclax, the combination appears to have no added toxicity, in addition there is evidence of synergistic, early clinical activity, with disease responses, in a group of heavily pretreated acute myeloid leukemia patients.”

“Increasingly, venetoclax is being used as a standard treatment in patients with AML, but resistance to salvage therapy after venetoclax use is common and yields limited benefit upon relapse; only about 10% of patients respond to salvage therapy after venetoclax failure, representing a significant need for patients with AML,” said Richard Ghalie, M.D., chief medical officer of MEI Pharma. “We see the voruciclib data to date demonstrating anti-leukemic activity as promising, particularly alongside the consistent reductions of Mcl-1 that provide evidence we are eliciting the anticipated biological response in patients, and we are excited to share additional updates as appropriate in the second half of 2024.”