Phase 2 study of subcutaneous omacetaxine mepesuccinate after TKI failure in patients with chronic-phase CML with T315I mutation

Area of Science:

• Oncology
• Hematology
• Pharmacology

Background:

• The BCR-ABL T315I mutation confers resistance to standard tyrosine kinase inhibitor (TKI) therapies in chronic myeloid leukemia (CML).
• There is a critical unmet need for effective treatments for CML patients with the T315I mutation who have failed prior TKI therapy.

Purpose of the Study:

• To assess the efficacy and safety of omacetaxine mepesuccinate in CML patients with the T315I mutation and a history of TKI failure.
• To evaluate response rates, duration of response, progression-free survival, and toxicity profiles of omacetaxine treatment.

Main Methods:

• A phase 2 clinical trial involving 62 CML patients in the chronic phase with T315I mutation and TKI failure.
• Patients received subcutaneous omacetaxine 1.25 mg/m(2) twice daily for 14 days every 28 days, followed by maintenance dosing.
• Treatment continued until hematologic response or a maximum of 6 cycles, with ongoing monitoring for efficacy and adverse events.

Main Results:

• Complete hematologic response was achieved in 77% of patients, with a median response duration of 9.1 months.
• Major cytogenetic response was observed in 23% of patients, including complete cytogenetic response in 16%.
• Median progression-free survival was 7.7 months. Grade 3/4 hematologic toxicities (thrombocytopenia, neutropenia, anemia) were manageable, and nonhematologic adverse events were mostly grade 1/2.

Conclusions:

• Omacetaxine mepesuccinate shows potential as a safe and effective therapeutic option for CML patients harboring the T315I mutation who have exhausted TKI treatment options.
• The observed hematologic and cytogenetic responses suggest omacetaxine can overcome TKI resistance mediated by the T315I mutation.