Contributions
Abstract: EP323
Type: E-Poster Presentation
Session title: Acute lymphoblastic leukemia - Biology & Translational Research
Background
Acute lymphoblastic leukemia (ALL) is a common hematological malignancy with poor survival, especially in adults. Adriamycin (ADM)-based chemotherapy is a standard regimen of human lymphoid malignancies, including ALL. However, chemo-resistance & relapse hindered the outcome of the chemotherapy in high risk ALL patients. Human CD47 is an integrin-associated protein and highly expressed in hematological malignancy cells. CD47 served as a ligand for signal regulatory protein-α (SIRP-α) which expressed on phagocytic cells and CD47 interaction with SIRP-α promotes to inhibit phagocytosis activity. Blocking anti-CD47 monoclonal antibody (mAb) can stimulate phagocytosis activity of macrophages. So far, anti-CD47 mAb and antibody combination with ADM therapy against drug resistance human ALL is not clearly investigated.
Aims
This study targeted to detect cell surface expression level of CD47 in ADM resistant ALL cells and investigate the efficacy treating potential of anti-CD47 mAb against ADM resistant ALL cells in preclinical mouse models.
Methods
Stably luciferase expressing parental Nalm-6-Luc-cells were subjected with ADM to establish ADM resistant cells. CD47 expression in ALL cells was analyzed using FACS. Anti-CD47 mediated phagocytosis in vitro assay was performed. NOD/SCID mouse in vivo preclinical model using anti-CD47 mAb, mAb combination with ADM, and ADM alone therapy against human ALL were established. Tumor volume and burden were monitored. Survival of the leukemic mice were observed in using different treatments.
Results
We successfully established potently ADM drug resistant human ALL cells Nalm-6-Luc-ADMR. We found that CD47 was highly expressed (over 98%) in the resistant Nalm-6-Luc-ADMR, Nalm-6-Luc (parental), Molt-4 and Jurkat ALL cells. High expression level of drug resistance genes and proteins in ADM resistant ALL cells were detected. Anti-CD47 mAb with the presence of macrophage enabled phagocytosis of drug resistant ALL cells in vitro assay. The anti-CD47 antibody enabled significant levels of phagocytosis with blast ALL cells using macrophage effector cells as compared to blank control and anti-CD45 antibody (P = 0.0001). In our preclinical mouse model, drug resistant ALL cells were significantly eliminated in ALL engrafted mice when treated with anti-CD47 mAb and mAb combination with ADM, whereas ADM alone and control mice remained at risk of leukemia burden. Moreover, with anti-CD47 antibody alone treatment, the highest (leukemia free) survival rate (over 5 months) without any relapse case was achieved.
Conclusion
Our current results indicated that targeting CD47 with anti-CD47 antibody therapy could effectively eliminate drug resistant ALL cells and provided a promising preclinical evidence for novel treatment in relapsed/refractory ALL.
Keyword(s): Acute lymphoblastic leukemia, Antibody, Drug resistance, Macrophage
Abstract: EP323
Type: E-Poster Presentation
Session title: Acute lymphoblastic leukemia - Biology & Translational Research
Background
Acute lymphoblastic leukemia (ALL) is a common hematological malignancy with poor survival, especially in adults. Adriamycin (ADM)-based chemotherapy is a standard regimen of human lymphoid malignancies, including ALL. However, chemo-resistance & relapse hindered the outcome of the chemotherapy in high risk ALL patients. Human CD47 is an integrin-associated protein and highly expressed in hematological malignancy cells. CD47 served as a ligand for signal regulatory protein-α (SIRP-α) which expressed on phagocytic cells and CD47 interaction with SIRP-α promotes to inhibit phagocytosis activity. Blocking anti-CD47 monoclonal antibody (mAb) can stimulate phagocytosis activity of macrophages. So far, anti-CD47 mAb and antibody combination with ADM therapy against drug resistance human ALL is not clearly investigated.
Aims
This study targeted to detect cell surface expression level of CD47 in ADM resistant ALL cells and investigate the efficacy treating potential of anti-CD47 mAb against ADM resistant ALL cells in preclinical mouse models.
Methods
Stably luciferase expressing parental Nalm-6-Luc-cells were subjected with ADM to establish ADM resistant cells. CD47 expression in ALL cells was analyzed using FACS. Anti-CD47 mediated phagocytosis in vitro assay was performed. NOD/SCID mouse in vivo preclinical model using anti-CD47 mAb, mAb combination with ADM, and ADM alone therapy against human ALL were established. Tumor volume and burden were monitored. Survival of the leukemic mice were observed in using different treatments.
Results
We successfully established potently ADM drug resistant human ALL cells Nalm-6-Luc-ADMR. We found that CD47 was highly expressed (over 98%) in the resistant Nalm-6-Luc-ADMR, Nalm-6-Luc (parental), Molt-4 and Jurkat ALL cells. High expression level of drug resistance genes and proteins in ADM resistant ALL cells were detected. Anti-CD47 mAb with the presence of macrophage enabled phagocytosis of drug resistant ALL cells in vitro assay. The anti-CD47 antibody enabled significant levels of phagocytosis with blast ALL cells using macrophage effector cells as compared to blank control and anti-CD45 antibody (P = 0.0001). In our preclinical mouse model, drug resistant ALL cells were significantly eliminated in ALL engrafted mice when treated with anti-CD47 mAb and mAb combination with ADM, whereas ADM alone and control mice remained at risk of leukemia burden. Moreover, with anti-CD47 antibody alone treatment, the highest (leukemia free) survival rate (over 5 months) without any relapse case was achieved.
Conclusion
Our current results indicated that targeting CD47 with anti-CD47 antibody therapy could effectively eliminate drug resistant ALL cells and provided a promising preclinical evidence for novel treatment in relapsed/refractory ALL.
Keyword(s): Acute lymphoblastic leukemia, Antibody, Drug resistance, Macrophage