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Pre-clinical Evaluation of Tyrosine Kinase Inhibitors for Treatment of Acute Leukemia
Published on: September 18, 2013
Preclinical evaluation of gemcitabine combination regimens for application in acute myeloid leukemia
Ryan H Shanks1, David A Rizzieri, James L Flowers
1North Carolina Central University and Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
The DNA antimetabolite gemcitabine is an anticancer agent with shown preclinical and clinical utility and a low toxicity profile. In this study, we sought to identify and optimize drug partners for binary and tertiary combinations with gemcitabine for use in the treatment of acute myelogenous leukemia (AML). Drug interaction was assessed by growth inhibition assay with metabolic end points. The combination index method was used to evaluate combinations of gemcitabine with fludarabine, paclitaxel, chlorambucil, doxorubicin, mitoxantrone, and SN-38 in U937 human AML cells. A three-dimensional method was used to determine the effect of dose ratio and schedule on drug interaction. Mechanisms underlying interactions related to cell cycle effects and apoptosis were assessed by flow cytometric and caspase-3 and -7 assays, respectively. The most synergistic binary combination was gemcitabine + fludarabine. The most synergistic tertiary combination was gemcitabine + fludarabine + paclitaxel, where the interaction was sequence dependent with paclitaxel given before gemcitabine + fludarabine, producing a 2-fold increase in synergy. Cell cycle analysis did not reveal a significant G(2)-M arrest, suggesting that the synergistic effect of paclitaxel in this combination, which produced the greatest caspase activation, might be independent of microtubule stabilization. In contrast, the gemcitabine + fludarabine + mitoxantrone combination was synergistic and schedule independent. Moreover, few ratios of gemcitabine + fludarabine to mitoxantrone were antagonistic, which could be important for clinical translation. In conclusion, synergistic interactions with gemcitabine occurred with several drugs, the most promising being gemcitabine + fludarabine, gemcitabine + fludarabine + paclitaxel, and gemcitabine + fludarabine + mitoxantrone. These findings provided a rationale for clinical trials of gemcitabine + fludarabine and gemcitabine + mitoxantrone where responses were observed in heavily pretreated AML patients.
Insights
Researchers identified optimal drug combinations for acute myelogenous leukemia (AML) treatment. Gemcitabine combined with fludarabine, paclitaxel, or mitoxantrone showed significant synergy, supporting clinical trials for AML therapy.
Area of Science:
- Pharmacology and Oncology
- Cancer Therapeutics
- Drug Discovery
Background:
- Gemcitabine is a DNA antimetabolite with established efficacy and low toxicity in cancer treatment.
- Identifying synergistic drug combinations is crucial for improving acute myelogenous leukemia (AML) therapy.
- Optimizing drug partners for gemcitabine can enhance treatment outcomes in AML.
Purpose of the Study:
- To identify and optimize binary and tertiary drug combinations with gemcitabine for AML treatment.
- To evaluate drug interactions using growth inhibition assays and combination index methods.
- To investigate the mechanisms of drug interactions, including cell cycle effects and apoptosis.
Main Methods:
- Assessed drug interactions using growth inhibition assays and metabolic end points.
- Employed the combination index method to evaluate gemcitabine with various agents in U937 human AML cells.
- Utilized three-dimensional methods, flow cytometry, and caspase assays to analyze drug interactions and mechanisms.
Main Results:
- The most synergistic binary combination identified was gemcitabine + fludarabine.
- The most synergistic tertiary combination was gemcitabine + fludarabine + paclitaxel, with sequence-dependent synergy.
- Gemcitabine + fludarabine + mitoxantrone demonstrated synergistic and schedule-independent interaction, with potential for clinical translation.
Conclusions:
- Synergistic interactions were observed between gemcitabine and several drugs, notably fludarabine, paclitaxel, and mitoxantrone.
- Gemcitabine + fludarabine, gemcitabine + fludarabine + paclitaxel, and gemcitabine + fludarabine + mitoxantrone are promising combinations for AML.
- These findings support the clinical investigation of gemcitabine + fludarabine and gemcitabine + mitoxantrone in AML patients.
