Contributions
Abstract: EP424
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by the accumulation of immature myeloid cells resulting in hematopoietic insufficiency such as cytopenia or anemia. SOC consists of cytarabine (ara-C) and anthracyclines or combinations of hypomethylating agents or low dose ara-C with BCL-2 protein inhibitor venetoclax. These strategies provide high initial response rates, yet only a fraction of patients achieve cure. Up-front resistance as well as relapse following initial therapy underlines the need for novel therapeutic approaches. Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate that leverages aminopeptidases and thereby rapidly delivers and releases alkylating agents in tumor cells. Increased expression of aminopeptidase N (ANPEP) has been associated with the malignant AML phenotype and is detected on stem cells and leukemic blasts. APN has been shown to hydrolyze melflufen providing a rational to evaluate melflufen efficacy in the relapsed/refractory (RR) AML setting.
Aims
To investigate the therapeutic potential of melflufen in cytarabine and venetoclax resistant AML cell lines in vitro and in vivo as well as in cells from relapsed AML patients ex vivo. A secondary aim was to investigate the expression profile of aminopeptidases and their relation to clinical parameters in AML patients.
Methods
The parental AML cell line MV4-11 and its venetoclax (MV4-11_VXR) and ara-C (MV4-11_aCR) resistant sublines were obtained from the RCCI collection of the University of Kent. In vitro drug toxicity was assessed using the CellTiter-Glo (CTG) viability assay. The expression of aminopeptidase was analyzed on previously sequenced/published AML samples. In vivo assessment of melflufen efficacy using chicken embryo chorioallantoic membrane (CAM) assay and ex vivo drug sensitivity assessment of melflufen in AML patient samples using high throughput multi-color flow cytometry are ongoing.
Results
Expression analysis of aminopeptidase in AML patient samples showed that multiple aminopeptidases, previously shown to hydrolyze melflufen including DPP7, LTA4H, RNPEP, ANPEP, are abundantly expressed in AML. In vitro drug efficacy evaluation showed that in parental MV4-11 cells 72h melflufen treatment results in high cell viability reduction similar to venetoclax (IC50 range 2-10 nM), while somewhat lower efficacy is seen for ara-C (IC50 400nM). Interestingly, MV4-11_VXR also displayed increased resistance to ara-C (IC50 2.5µM) indicating overlapping resistance mechanisms for the two drugs. Importantly, in both MV4-11_VXR and MV4-11_aCR sublines melflufen efficacy was retained, suggesting that melflufen could target both resistant cell populations.
Conclusion
In summary, melflufen demonstrates high efficacy in venetoclax and ara-C resistant AML models in vitro. In addition, abundant expression of aminopeptidases in the AML patient samples provides rational for further clinical evaluation of melflufen in the RR AML setting.
Keyword(s): AML, Cytarabine, Refractory, Resistance
Abstract: EP424
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by the accumulation of immature myeloid cells resulting in hematopoietic insufficiency such as cytopenia or anemia. SOC consists of cytarabine (ara-C) and anthracyclines or combinations of hypomethylating agents or low dose ara-C with BCL-2 protein inhibitor venetoclax. These strategies provide high initial response rates, yet only a fraction of patients achieve cure. Up-front resistance as well as relapse following initial therapy underlines the need for novel therapeutic approaches. Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate that leverages aminopeptidases and thereby rapidly delivers and releases alkylating agents in tumor cells. Increased expression of aminopeptidase N (ANPEP) has been associated with the malignant AML phenotype and is detected on stem cells and leukemic blasts. APN has been shown to hydrolyze melflufen providing a rational to evaluate melflufen efficacy in the relapsed/refractory (RR) AML setting.
Aims
To investigate the therapeutic potential of melflufen in cytarabine and venetoclax resistant AML cell lines in vitro and in vivo as well as in cells from relapsed AML patients ex vivo. A secondary aim was to investigate the expression profile of aminopeptidases and their relation to clinical parameters in AML patients.
Methods
The parental AML cell line MV4-11 and its venetoclax (MV4-11_VXR) and ara-C (MV4-11_aCR) resistant sublines were obtained from the RCCI collection of the University of Kent. In vitro drug toxicity was assessed using the CellTiter-Glo (CTG) viability assay. The expression of aminopeptidase was analyzed on previously sequenced/published AML samples. In vivo assessment of melflufen efficacy using chicken embryo chorioallantoic membrane (CAM) assay and ex vivo drug sensitivity assessment of melflufen in AML patient samples using high throughput multi-color flow cytometry are ongoing.
Results
Expression analysis of aminopeptidase in AML patient samples showed that multiple aminopeptidases, previously shown to hydrolyze melflufen including DPP7, LTA4H, RNPEP, ANPEP, are abundantly expressed in AML. In vitro drug efficacy evaluation showed that in parental MV4-11 cells 72h melflufen treatment results in high cell viability reduction similar to venetoclax (IC50 range 2-10 nM), while somewhat lower efficacy is seen for ara-C (IC50 400nM). Interestingly, MV4-11_VXR also displayed increased resistance to ara-C (IC50 2.5µM) indicating overlapping resistance mechanisms for the two drugs. Importantly, in both MV4-11_VXR and MV4-11_aCR sublines melflufen efficacy was retained, suggesting that melflufen could target both resistant cell populations.
Conclusion
In summary, melflufen demonstrates high efficacy in venetoclax and ara-C resistant AML models in vitro. In addition, abundant expression of aminopeptidases in the AML patient samples provides rational for further clinical evaluation of melflufen in the RR AML setting.
Keyword(s): AML, Cytarabine, Refractory, Resistance