Tolero Pharmaceuticals Announces First Patient Dosed in Phase 2 Zella 202 Study of Investigational Agent Alvocidib in Patients with Relapsed or Refractory Acute Myeloid Leukemia Following Treatment with Venetoclax and HMA Combination Therapy

SALT LAKE CITY, Jan. 15, 2020 /PRNewswire/ -- Tolero Pharmaceuticals, Inc., a clinical-stage company focused on developing novel therapeutics for hematological and oncological diseases, today announced that the first patient has been dosed in a Phase 2 study evaluating the investigational agent alvocidib, a potent CDK9 inhibitor, in patients with acute myeloid leukemia (AML) who have either relapsed from or are refractory to venetoclax in combination with a hypomethylating agent (HMA). The open-label, randomized study has two parts and will evaluate the safety and efficacy of alvocidib in monotherapy or in combination with low-dose cytarabine.

"Patients with AML who are resistant to or progressed following treatment with the BCL-2 inhibitor venetoclax in combination with an HMA have limited treatment options, and it has been well established in the literature that a key potential mechanism of resistance to BCL-2 targeted therapy is the switch to a dependence on MCL-1," said David J. Bearss, Ph.D., Chief Executive Officer of Tolero Pharmaceuticals, Inc. "The initiation of this study marks an important step toward understanding the potential of alvocidib as a monotherapy or in combination with low-dose cytarabine for these patients. We believe that patients whose cancers have progressed following treatment with venetoclax may be sensitive to alvocidib and this trial will help us to better understand this hypothesis."

The primary objective of the Phase 2 study is to determine the rate of combined complete remission (CR) and CR with incomplete hematological recovery (CRi), of alvocidib and alvocidib in combination with low-dose cytarabine in patients with AML. Secondary objectives include establishing the recommended treatment regimen for the second part of the study and evaluating the median overall survival (mOS) and CR rate. Additional secondary outcome measures include evaluating event-free survival (EFS), duration of composite CR (CRc), safety and tolerability of the regimen and mortality.

In the first part of the study, patients who are refractory to or have relapsed on venetoclax in combination with an HMA will be randomized into two arms. In Arm 1 of the study, patients will receive combination therapy of alvocidib and low-dose cytarabine. In Arm 2 of the study, patients will receive alvocidib monotherapy. In the second part of the study, patients will receive the regimen based on the outcome of the first part.

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 (NCT03969420).

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 azacytidine or decitabine (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 (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.(1) In normal function, it is essential for early embryonic development and for the survival of multiple cell lineages, including lymphocytes and hematopoietic stem cells.(2) MCL-1 inhibits apoptosis and sustains the survival of leukemic blasts, which may lead to relapse or resistance to treatment.(1,3) The expression of MCL-1 in leukemic blasts is regulated by cyclin-dependent kinase 9 (CDK9).(4,5) 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.(4) 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.(1)

About Tolero Pharmaceuticals, Inc.
Tolero Pharmaceuticals is a clinical-stage biopharmaceutical company researching and developing treatments to improve and extend the lives of patients with hematological and oncological diseases. Tolero has a diverse pipeline that targets important biological drivers of blood disorders to treat leukemias, anemia, and solid tumors, as well as targets of drug resistance and transcriptional control.

Tolero Pharmaceuticals is based in the United States and is an indirect, wholly-owned subsidiary of Sumitomo Dainippon Pharma Co., Ltd., a pharmaceutical company based in Japan. Tolero works closely with its parent company, Sumitomo Dainippon Pharma, and Boston Biomedical, Inc., also a wholly-owned subsidiary, to advance a pipeline of innovative oncology treatments. The organizations apply their expertise and collaborate to achieve a common objective - expediting the discovery, development and commercialization of novel treatment options.

Additional information about the company and its product pipeline can be found at

Tolero Pharmaceuticals Forward-Looking Statements
This press release contains "forward-looking statements," as that term is defined in the Private Securities Litigation Reform Act of 1995 regarding the research, development and commercialization of pharmaceutical products. The forward-looking statements in this press release are based on management's assumptions and beliefs in light of information presently available, and involve both known and unknown risks and uncertainties, which could cause actual outcomes to differ materially from current expectations. Any forward-looking statements set forth in this press release speak only as of the date of this press release. We do not undertake to update any of these forward-looking statements to reflect events or circumstances that occur after the date hereof. Information concerning pharmaceuticals (including compounds under development) contained within this material is not intended as advertising or medical advice.


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