Table_3_Preclinical Evaluation of Carfilzomib for Infant KMT2A-Rearranged Acute Lymphoblastic Leukemia.xlsx

BackgroundInfants with KMT2A-rearranged B-cell precursor acute lymphoblastic leukemia (ALL) have poor outcomes. There is an urgent need to identify novel agents to improve survival. Proteasome inhibition has emerged as a promising therapeutic strategy for several hematological malignancies. The aim of this study was to determine the preclinical efficacy of the selective proteasome inhibitor carfilzomib, for infants with KMT2A-rearranged ALL.
MethodsEight infant ALL cell lines were extensively characterized for immunophenotypic and cytogenetic features. In vitro cytotoxicity to carfilzomib was assessed using a modified Alamar Blue assay with cells in logarithmic growth. The Bliss Independence model was applied to determine synergy between carfilzomib and the nine conventional chemotherapeutic agents used to treat infants with ALL. Established xenograft models were used to identify the maximal tolerated dose of carfilzomib and determine in vivo efficacy.
ResultsCarfilzomib demonstrated low IC50 concentrations within the nanomolar range (6.0–15.8 nm) across the panel of cell lines. Combination drug testing indicated in vitro synergy between carfilzomib and several conventional chemotherapeutic agents including vincristine, daunorubicin, dexamethasone, L-asparaginase, and 4-hydroperoxycyclophosphamide. In vivo assessment did not lead to a survival advantage for either carfilzomib monotherapy, when used to treat both low or high disease burden, or for carfilzomib in combination with multi-agent induction chemotherapy comprising of vincristine, dexamethasone, and L-asparaginase.
ConclusionsOur study highlights that in vitro efficacy does not necessarily translate to benefit in vivo and emphasizes the importance of in vivo validation prior to suggesting an agent for clinical use. Whilst proteasome inhibitors have an important role to play in several hematological malignancies, our findings guard against prioritization of carfilzomib for treatment of KMT2A-rearranged infant ALL in the clinical setting.

背景 携带KMT2A重排的B细胞前体急性淋巴细胞白血病（acute lymphoblastic leukemia, ALL）患儿预后不佳，目前亟需发掘新型治疗药物以改善此类患儿的生存预后。蛋白酶体抑制已成为多种血液系统恶性肿瘤颇具前景的治疗策略。本研究旨在评估选择性蛋白酶体抑制剂（proteasome inhibitor）卡非佐米（carfilzomib）针对KMT2A重排ALL患儿的临床前疗效。
方法 本研究对8株婴儿ALL细胞系的免疫表型与细胞遗传学特征进行了全面表征。采用改良的阿尔玛蓝（Alamar Blue）检测法，对处于对数生长期的细胞进行卡非佐米体外细胞毒性评估；运用布利斯独立模型（Bliss Independence model）分析卡非佐米与9种临床治疗婴儿ALL的传统化疗药物之间的协同作用。利用已建立的异种移植模型（xenograft model）确定卡非佐米的最大耐受剂量，并评估其体内疗效。
结果 在所检测的细胞系面板中，卡非佐米的半最大效应浓度（IC50）处于纳摩尔级别（6.0~15.8 nM）。联合用药试验显示，卡非佐米与长春新碱、柔红霉素、地塞米松、L-天冬酰胺酶及4-过氧环磷酰胺等多种传统化疗药物具有体外协同作用。体内评估结果显示，无论用于低肿瘤负荷还是高肿瘤负荷患儿的单药治疗，卡非佐米单药均未带来生存获益；其与长春新碱、地塞米松及L-天冬酰胺酶组成的多药诱导化疗方案联合使用时，同样未产生生存优势。
结论 本研究表明，体外疗效未必能转化为体内获益，强调了在推荐药物进入临床应用前开展体内验证的重要性。尽管蛋白酶体抑制剂在多种血液系统恶性肿瘤中具有重要治疗价值，但本研究结果提示，临床不应优先将卡非佐米用于治疗KMT2A重排的婴儿ALL患儿。