Abstract 344: SJP1604, a novel targeted therapeutic agent for AML (acute myeloid leukemia) including standard therapy-resistant AML
Authors: Um Jihyun , Lee Dohyeong , Oh Jisun , Park Yongbin , Moon Sung Hwan , Lee Su Jin , Ki Min-Hyo , Cho Eui Hwan 
Published: August 2019

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are cancers characterized by the rapid growth of abnormal white blood cells. Generally, cytarabine (Ara-C), azacitidine, and decitabine are treated as the standard first-line chemotherapy for AML/MDS. Although the therapy leads to high rates of remission, approximately 30% of the treated patients are refractory and more than 50% of them face a relapse because of the occurrence of drug resistance and high toxicity. Therefore, there is a strong unmet need for the next-generation targeted therapy to overcome drug resistance and reduce toxicity in AML/MDS. Here, we designed an aptamer-nucleoside drug conjugate (SJP1604) via utilizing easy and continuous synthesis specific for nucleolin, which is highly expressed only on the cell membrane of cancer cells. In particular, AML, CLL (chronic lymphoblastic leukemia) and ALL (acute lymphoblastic leukemia) cells are known to express the highest mRNA level of nucleolin among various cancer cells, relatively. SJP1604 can be delivered into cancer cells with its high targeting ability and plasma stability via its unique conformational property. In this study, we verified that SJP1604 selectively targeted cancer cells by nucleolin-binding on the cancer cell membrane in the drug uptake assay. Owing to the selectivity, SJP1604 demonstrated less cytotoxicity on murine bone marrow cells in vitro and mouse white blood cells in vivo. SJP1604 also exhibited a long-lasting plasma stability in 50% human plasma up to 48 hours in contrast to unstability of general aptamers. Furthermore, SJP1604 inhibited the growth of various human AML/MDS cancer cells. Interestingly, SJP1604 showed the significantly reduced IC50 values with the decreased expression level of nucleolin in cytarabine-, azacitidine- and decitabine-resistant MOLM-13 while cytarabine caused no effect on the cell growth and the expression of nucleolin of the same resistant cell lines. Injection of SJP1604 led to tumor regression and improved survival rate in MOLM-13 xenograft mouse model and C1498 syngeneic mouse model. In ex vivo study, we figured out that the expression level of nucleolin is highly up-regulated in AML patient-derived bone marrow cells and the level is much higher in relapsed/refractory (R/R) AML patient-derived bone marrow cells. Moreover, SJP1604 also significantly reduced the colony forming unit (CFU) of R/R AML patient-derived bone marrow cells compared to that of AS1411 treatment. In conclusion, these findings suggest that SJP1604 could be developed as a first-in-class drug for novel targeted therapy of AML/MDS with less drug toxicity as well as as a remarkable orphan drug for overcoming drug resistance of AML/MDS in which distinctive solutions do not exist up until recently.

Citation Format: Jihyun Um, Dohyeong Lee, Jisun Oh, Yongbin Park, Sung Hwan Moon, Su Jin Lee, Min-Hyo Ki, Eui Hwan Cho. SJP1604, a novel targeted therapeutic agent for AML (acute myeloid leukemia) including standard therapy-resistant AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 344.