Purpose: The dual BCR-ABL/SRC kinase inhibitor dasatinib entered the clinic for the treatment of chronic myeloid leukemia and Ph + acute lymphoblastic leukemia. Because SRC kinases are known to play an important role in physiologicT-cell activation, we analyzed the immunobiological effects of dasatinib on T-cell function. The effect of dasatinib on multiple T-cell effector functions was examined at clinically relevant doses (1-100 nmol/L); the promiscuous tyrosine kinase inhibitor staurosporine was used as a comparator. Experimental Design: Purified human CD3 + cells and virus-specific CD8 + Tcells from healthy blood donors were studied directly ex vivo ; antigen-specific effects were confirmed in defined T-cell clones. Functional outcomes included cytokine production (interleukin-2, IFNg, and tumor necrosis factor a), degranulation (CD107a/b mobilization), activation (CD69 up-regulation), proliferation (carboxyfluorescein diacetate succinimidyl ester dilution), apoptosis/necrosis induction, and signal transduction. Results: Both dasatinib and staurosporine inhibited T-cell activation, proliferation, cytokine production, and degranulation in a dose-dependent manner. Mechanistically, this was mediated by the blockade of early signal transduction events and was not due to loss of T-cell viability. Overall, CD4 + T cells seemed to be more sensitive to these effects than CD8 + Tcells, and naBve Tcells more sensitive than memoryT-cell subsets. The inhibitory effects of dasatinib were so profound that all T-cell effector functions were shut down at therapeutically relevant concentrations. Conclusion: These findings indicate that caution is warranted with use of this drug in the clinical setting and provide a rationale to explore the potential of dasatinib as an immunosuppressant in the fields of transplantation and T-cell^driven autoimmune diseases.

Supplementary Figure S1 from Profound Inhibition of Antigen-Specific T-Cell Effector Functions by Dasatinib

Supplementary Figure S1 from Profound Inhibition of Antigen-Specific T-Cell Effector Functions by Dasatinib

<div>Abstract<p><b>Purpose:</b> The dual BCR-ABL/SRC kinase inhibitor dasatinib entered the clinic for the treatment of chronic myeloid leukemia and Ph⁺ acute lymphoblastic leukemia. Because SRC kinases are known to play an important role in physiologic T-cell activation, we analyzed the immunobiological effects of dasatinib on T-cell function. The effect of dasatinib on multiple T-cell effector functions was examined at clinically relevant doses (1-100 nmol/L); the promiscuous tyrosine kinase inhibitor staurosporine was used as a comparator.</p><p><b>Experimental Design:</b> Purified human CD3⁺ cells and virus-specific CD8⁺ T cells from healthy blood donors were studied directly <i>ex vivo</i>; antigen-specific effects were confirmed in defined T-cell clones. Functional outcomes included cytokine production (interleukin-2, IFNγ, and tumor necrosis factor α), degranulation (CD107a/b mobilization), activation (CD69 up-regulation), proliferation (carboxyfluorescein diacetate succinimidyl ester dilution), apoptosis/necrosis induction, and signal transduction.</p><p><b>Results:</b> Both dasatinib and staurosporine inhibited T-cell activation, proliferation, cytokine production, and degranulation in a dose-dependent manner. Mechanistically, this was mediated by the blockade of early signal transduction events and was not due to loss of T-cell viability. Overall, CD4⁺ T cells seemed to be more sensitive to these effects than CD8⁺ T cells, and na<i>ï</i>ve T cells more sensitive than memory T-cell subsets. The inhibitory effects of dasatinib were so profound that all T-cell effector functions were shut down at therapeutically relevant concentrations.</p><p><b>Conclusion:</b> These findings indicate that caution is warranted with use of this drug in the clinical setting and provide a rationale to explore the potential of dasatinib as an immunosuppressant in the fields of transplantation and T-cell–driven autoimmune diseases.</p></div>

<div>Abstract<p><b>Purpose:</b> The dual BCR-ABL/SRC kinase inhibitor dasatinib entered the clinic for the treatment of chronic myeloid leukemia and Ph⁺ acute lymphoblastic leukemia. Because SRC kinases are known to play an important role in physiologic T-cell activation, we analyzed the immunobiological effects of dasatinib on T-cell function. The effect of dasatinib on multiple T-cell effector functions was examined at clinically relevant doses (1-100 nmol/L); the promiscuous tyrosine kinase inhibitor staurosporine was used as a comparator.</p><p><b>Experimental Design:</b> Purified human CD3⁺ cells and virus-specific CD8⁺ T cells from healthy blood donors were studied directly <i>ex vivo</i>; antigen-specific effects were confirmed in defined T-cell clones. Functional outcomes included cytokine production (interleukin-2, IFNγ, and tumor necrosis factor α), degranulation (CD107a/b mobilization), activation (CD69 up-regulation), proliferation (carboxyfluorescein diacetate succinimidyl ester dilution), apoptosis/necrosis induction, and signal transduction.</p><p><b>Results:</b> Both dasatinib and staurosporine inhibited T-cell activation, proliferation, cytokine production, and degranulation in a dose-dependent manner. Mechanistically, this was mediated by the blockade of early signal transduction events and was not due to loss of T-cell viability. Overall, CD4⁺ T cells seemed to be more sensitive to these effects than CD8⁺ T cells, and na<i>ï</i>ve T cells more sensitive than memory T-cell subsets. The inhibitory effects of dasatinib were so profound that all T-cell effector functions were shut down at therapeutically relevant concentrations.</p><p><b>Conclusion:</b> These findings indicate that caution is warranted with use of this drug in the clinical setting and provide a rationale to explore the potential of dasatinib as an immunosuppressant in the fields of transplantation and T-cell–driven autoimmune diseases.</p></div>