Cancer Research Institute Ghent (CRIG), Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Ghent, Belgium; Department of Diagnostic Sciences, Ghent University, Ghent.
Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago.
Haematologica. 2023 Feb 1;108(2):409-419. doi: 10.3324/haematol.2022.281390.
Asparagine is a non-essential amino acid since it can either be taken up via the diet or synthesized by asparagine synthetase. Acute lymphoblastic leukemia (ALL) cells do not express asparagine synthetase or express it only minimally, which makes them completely dependent on extracellular asparagine for their growth and survival. This dependency makes ALL cells vulnerable to treatment with L-asparaginase, an enzyme that hydrolyzes asparagine. To date, all clinically approved L-asparaginases have significant L-glutaminase co-activity, associated with non-immune related toxic side effects observed during therapy. Therefore, reduction of L-glutaminase co-activity with concomitant maintenance of its anticancer L-asparaginase effect may effectively improve the tolerability of this unique drug. Previously, we designed a new alternative variant of Erwinia chrysanthemi (ErA; Erwinaze) with decreased L-glutaminase co-activity, while maintaining its L-asparaginase activity, by the introduction of three key mutations around the active site (ErA-TM). However, Erwinaze and our ErA-TM variant have very short half-lives in vivo. Here, we show that the fusion of ErA-TM with an albumin binding domain (ABD)-tag significantly increases its in vivo persistence. In addition, we evaluated the in vivo therapeutic efficacy of ABD-ErA-TM in a B-ALL xenograft model of SUP-B15. Our results show a comparable long-lasting durable antileukemic effect between the standard-of-care pegylated-asparaginase and ABD-ErA-TM L-asparaginase, but with fewer co-glutaminase-related acute side effects. Since the toxic side effects of current L-asparaginases often result in treatment discontinuation in ALL patients, this novel ErA-TM variant with ultra-low L-glutaminase co-activity and long in vivo persistence may have great clinical potential.
天冬酰胺是一种非必需氨基酸，因为它可以通过饮食摄取或由天冬酰胺合成酶合成。急性淋巴细胞白血病（ALL）细胞不表达天冬酰胺合成酶或仅微量表达，这使其完全依赖细胞外天冬酰胺来生长和存活。这种依赖性使 ALL 细胞容易受到 L-天冬酰胺酶的治疗，L-天冬酰胺酶是一种水解天冬酰胺的酶。迄今为止，所有临床批准的 L-天冬酰胺酶都具有显著的 L-谷氨酰胺酶协同活性，与治疗过程中观察到的非免疫相关毒性副作用有关。因此，降低 L-谷氨酰胺酶协同活性，同时保持其抗癌 L-天冬酰胺酶作用，可能有效地提高这种独特药物的耐受性。以前，我们通过在活性位点周围引入三个关键突变（ErA-TM），设计了一种新的替代变体，即产肠毒素大肠杆菌（Erwinia chrysanthemi；ErA；Erwinaze），具有降低的 L-谷氨酰胺酶协同活性，同时保持其 L-天冬酰胺酶活性。然而，Erwinaze 和我们的 ErA-TM 变体在体内的半衰期非常短。在这里，我们表明，ErA-TM 与白蛋白结合结构域（ABD）-标签的融合显著增加了其体内持久性。此外，我们在 SUP-B15 的 B-ALL 异种移植模型中评估了 ABD-ErA-TM 的体内治疗效果。我们的结果表明，在标准护理聚乙二醇化天冬酰胺酶和 ABD-ErA-TM L-天冬酰胺酶之间，具有类似的持久持久抗白血病作用，但与较少的共同谷氨酰胺酶相关的急性副作用。由于当前 L-天冬酰胺酶的毒性副作用经常导致 ALL 患者停止治疗，因此这种新型 ErA-TM 变体具有超低的 L-谷氨酰胺酶协同活性和长的体内持久性，可能具有巨大的临床潜力。
