On May 14, 2020 Tolero Pharmaceuticals, Inc., a clinical-stage company focused on developing novel therapeutics for hematological and oncological diseases, reported that the first patient has been dosed with a one-hour dosing schedule for investigational agent alvocidib, a potent CDK9 inhibitor, administered in sequence after azacitidine, in the expansion of the Phase 1b/2 Zella 102 study in patients with myelodysplastic syndromes (MDS) (Press release, Tolero Pharmaceuticals, MAY 14, 2020, View Source [SID1234558096]).

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The Zella 102 study is being conducted in patients with previously untreated MDS and patients with MDS who have received fewer than six cycles of treatment with a hypomethylating agent. The initial study design was to evaluate the safety and efficacy of alvocidib using a 30-minute bolus followed by a four-hour intravenous infusion (IVI), in combination with decitabine. An amendment was made to the study design to include treatment with azacitidine, in sequence before a one-hour infusion of alvocidib.

"We are pleased that this study now includes both standard of care hypomethylating agents for patients with myelodysplastic syndromes. In addition, the expansion of this study offers an alternative alvocidib dosing schedule, which reduces the amount of time patients spend in infusion," said David J. Bearss, Ph.D., Chief Executive Officer, Tolero Pharmaceuticals, and Chief Scientific Officer and Global Head of Research, Global Oncology. "Preclinical research suggests that treatment with hypomethylating agents may sensitize MDS blast cells to suppression of MCL-1 through alvocidib. We look forward to building our understanding of the potential role of alvocidib in this patient population."

MDS is a form of cancer that can occur when cells in the bone marrow are abnormal and create defective blood cells, which often die earlier than normal cells. In one of three patients, MDS can progress into AML, a rapidly growing cancer of bone marrow cells.1

About the Zella 102 Study

The Zella 102 study is an open-label, dose-escalation Phase 1b/2 study evaluating the safety and efficacy of alvocidib, when administered in sequence after either decitabine or azacitidine, in patients with previously untreated MDS and patients with MDS who have received fewer than six cycles of treatment with hypomethylating agents. The primary objective of the Phase 1b portion of the study is to determine the maximum tolerated dose and recommended Phase 2 dose of alvocidib, when administered in these regimens. Secondary objectives are to determine the complete response rate and if treatment with alvocidib, administered in sequence after decitabine or azacitidine, results in improvements in transfusion dependence and/or hemoglobin level.

The primary objective of the Phase 2 portion of the study will be to determine the objective response rate of alvocidib, when administered to untreated patients with de novo or secondary MDS in sequence after a hypomethylating agent, using revised International Working Group (IWG) criteria.

The trial is being conducted at sites in the United States. Additional information on this trial, including comprehensive inclusion and exclusion criteria, can be accessed at www.ClinicalTrials.gov (NCT03593915).

About Alvocidib

Alvocidib is an investigational small molecule inhibitor of cyclin-dependent kinase 9 (CDK9) currently being evaluated in the Phase 2 studies Zella 202, in patients with acute myeloid leukemia (AML) who have either relapsed from or are refractory to venetoclax in combination with decitabine or azacitidine (NCT03969420) and Zella 201, in patients with relapsed or refractory MCL-1 dependent AML, in combination with cytarabine and mitoxantrone (NCT02520011). Alvocidib is also being evaluated in Zella 101, a Phase 1 clinical study evaluating the maximum tolerated dose, safety and clinical activity of alvocidib in combination with cytarabine and daunorubicin (7+3) in newly diagnosed patients with AML (NCT03298984), and Zella 102, a Phase 1b/2 study in patients with myelodysplastic syndromes (MDS) in combination with decitabine or azacitidine (NCT03593915). In addition, alvocidib is being evaluated in a Phase 1 study in patients with relapsed or refractory AML in combination with venetoclax (NCT03441555).

About CDK9 Inhibition and MCL-1

MCL-1 is a member of the apoptosis-regulating BCL-2 family of proteins.2 In normal function, it is essential for early embryonic development and for the survival of multiple cell lineages, including lymphocytes and hematopoietic stem cells.3 MCL-1 inhibits apoptosis and sustains the survival of leukemic blasts, which may lead to relapse or resistance to treatment.2,4 The expression of MCL-1 in leukemic blasts is regulated by cyclin-dependent kinase 9 (CDK9).5,6 Because of the short half-life of MCL-1 (2-4 hours), the effects of targeting upstream pathways are expected to reduce MCL-1 levels rapidly.5 Inhibition of CDK9 has been shown to block MCL-1 transcription, resulting in the rapid downregulation of MCL-1 protein, thus restoring the normal apoptotic regulation.2