Contributions
Abstract: EP400
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Acute myeloid leukemia (AML) is a disease characterized by transcriptional dysregulation, that results in a block in differentiation and aberrant self-renewal. Inhibitors directed to epigenetic modifiers, aiming at transcriptional reprogramming of AML cells, are currently in clinical trials for AML patients. Several of these inhibitors target bromodomain and extra-terminal domain (BET) proteins, cyclic AMP response binding protein-binding protein (CBP), and the E1A-interacting protein of 300 kDa (p300), affecting histone acetylation. Unfortunately, single epigenetic inhibitors showed limited efficacy due to appearance of resistance and lack of effective eradication of leukemic stem cells.
Aims
To evaluate the efficacy of the novel dual BET and CBP/p300 inhibitors NEO2734 and NEO1132 in the elimination of AML (stem/progenitor) cells.
Methods
We investigated the efficacy of NEO2734, NEO1132 and the CBP/p300 inhibitor CPI637 to induce cell death in AML cell lines and primary AML (stem/progenitor) cells. Moreover, we studied the effect of treatment with the NEO drugs on myeloid blast proliferation, apoptosis, clonogenic capacity of long- and short-term surviving AML cells ex vivo, on engraftment potential in a patient-derived xenograft AML mouse model (NSG mice injected with primary AML), and we determined the toxicity of the NEO drugs on normal hematopoietic cells.
Results
The two novel, orally available inhibitors NEO1132 and NEO2734 targeting both the BET and CBP/p300 proteins inhibited proliferation of a panel of AML cell lines, NEO2734 being the most potent, with IC50 values ranging from 27 nM to 125 nM. Both NEO1132 and NEO2734 induced apoptosis by downregulating c-Myc and Bcl2. Moreover, incubation of primary AML samples with the NEO drugs eliminated leukemic CD45dim blasts, myeloid CD45dimCD33+ leukemia cells, and CD45dimCD34+ immature blasts, while the lymphocytes were unaffected. Both NEO2734 and NEO1132 induced apoptosis in primary CD45dim leukemic blasts (Figure 1A). Importantly, treatment with NEO1132 and NEO2734 resulted in a significant reduction in clonogenic capacity of leukemic stem/progenitor cells from AML patient samples. Already after treatment with 10 nM a significant reduction in the number of colonies was observed in all tested primary AML cases (Figure 1B). To evaluate the potential of the NEO drugs to reduce human AML burden in vivo, primary AML cells were injected into NSG mice and the mice were orally treated with NEO2734 or NEO1132 (10 mg/kg for 11 times). A significant reduction in leukemic burden in the bone marrows of the mice was observed after treatment with NEO2734. Finally, we demonstrated that NEO2734 increased effectiveness of combination chemotherapy treatment in vivo.
To restore normal hematopoiesis after therapy, therapeutic approaches targeting leukemia cells should spare normal hematopoietic cells. Both NEO2734 and NEO1132 reduced the survival of normal human bone marrow cells only at high concentrations (1 µM), and with a 3.4-fold and 2.0-fold lower efficiency than the drugs affected primary AML cells. Oral treatment with NEO2734 or NEO1132 did not significantly reduce the weight of the mice, and did not affect the survival of normal mouse hematopoietic cells.
Conclusion
The dual BET-CBP/P300 inhibitor NEO2734 eliminates AML blasts and LSCs/progenitors in a nanomolar concentration, implicating that dual inhibition of BET and CBP/p300 using NEO2734 is a promising therapeutic strategy for AML patients, making it a focus for clinical translation.
Keyword(s): AML, Epigenetic, Leukemic stem cell, Therapy
Abstract: EP400
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Acute myeloid leukemia (AML) is a disease characterized by transcriptional dysregulation, that results in a block in differentiation and aberrant self-renewal. Inhibitors directed to epigenetic modifiers, aiming at transcriptional reprogramming of AML cells, are currently in clinical trials for AML patients. Several of these inhibitors target bromodomain and extra-terminal domain (BET) proteins, cyclic AMP response binding protein-binding protein (CBP), and the E1A-interacting protein of 300 kDa (p300), affecting histone acetylation. Unfortunately, single epigenetic inhibitors showed limited efficacy due to appearance of resistance and lack of effective eradication of leukemic stem cells.
Aims
To evaluate the efficacy of the novel dual BET and CBP/p300 inhibitors NEO2734 and NEO1132 in the elimination of AML (stem/progenitor) cells.
Methods
We investigated the efficacy of NEO2734, NEO1132 and the CBP/p300 inhibitor CPI637 to induce cell death in AML cell lines and primary AML (stem/progenitor) cells. Moreover, we studied the effect of treatment with the NEO drugs on myeloid blast proliferation, apoptosis, clonogenic capacity of long- and short-term surviving AML cells ex vivo, on engraftment potential in a patient-derived xenograft AML mouse model (NSG mice injected with primary AML), and we determined the toxicity of the NEO drugs on normal hematopoietic cells.
Results
The two novel, orally available inhibitors NEO1132 and NEO2734 targeting both the BET and CBP/p300 proteins inhibited proliferation of a panel of AML cell lines, NEO2734 being the most potent, with IC50 values ranging from 27 nM to 125 nM. Both NEO1132 and NEO2734 induced apoptosis by downregulating c-Myc and Bcl2. Moreover, incubation of primary AML samples with the NEO drugs eliminated leukemic CD45dim blasts, myeloid CD45dimCD33+ leukemia cells, and CD45dimCD34+ immature blasts, while the lymphocytes were unaffected. Both NEO2734 and NEO1132 induced apoptosis in primary CD45dim leukemic blasts (Figure 1A). Importantly, treatment with NEO1132 and NEO2734 resulted in a significant reduction in clonogenic capacity of leukemic stem/progenitor cells from AML patient samples. Already after treatment with 10 nM a significant reduction in the number of colonies was observed in all tested primary AML cases (Figure 1B). To evaluate the potential of the NEO drugs to reduce human AML burden in vivo, primary AML cells were injected into NSG mice and the mice were orally treated with NEO2734 or NEO1132 (10 mg/kg for 11 times). A significant reduction in leukemic burden in the bone marrows of the mice was observed after treatment with NEO2734. Finally, we demonstrated that NEO2734 increased effectiveness of combination chemotherapy treatment in vivo.
To restore normal hematopoiesis after therapy, therapeutic approaches targeting leukemia cells should spare normal hematopoietic cells. Both NEO2734 and NEO1132 reduced the survival of normal human bone marrow cells only at high concentrations (1 µM), and with a 3.4-fold and 2.0-fold lower efficiency than the drugs affected primary AML cells. Oral treatment with NEO2734 or NEO1132 did not significantly reduce the weight of the mice, and did not affect the survival of normal mouse hematopoietic cells.
Conclusion
The dual BET-CBP/P300 inhibitor NEO2734 eliminates AML blasts and LSCs/progenitors in a nanomolar concentration, implicating that dual inhibition of BET and CBP/p300 using NEO2734 is a promising therapeutic strategy for AML patients, making it a focus for clinical translation.
Keyword(s): AML, Epigenetic, Leukemic stem cell, Therapy