Pharmacokinetically stabilized cystine knot peptides that bind alpha-v-beta-6 integrin with single-digit nanomolar affinities for detection of pancreatic cancer.
Pharmacokinetically stabilized cystine knot peptides that bind alpha-v-beta-6 integrin with single-digit nanomolar affinities for detection of pancreatic cancer.
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DOI：
10.1158/1078-0432.ccr-11-1116
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发表时间：
2012-02-01
期刊：
影响因子：
--
通讯作者：
Gambhir SS
中科院分区：
文献类型：
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作者：
Kimura RH;Teed R;Hackel BJ;Pysz MA;Chuang CZ;Sathirachinda A;Willmann JK;Gambhir SS
胰腺癌的检测仍然是高度优先的，并且临床应用需要有效的诊断工具。许多癌细胞过度表达整合素αvβ6，整合素α vβ6是一种被评估为新型临床生物标志物的细胞表面受体。为了验证该分子靶标，通过定向进化工程化了几种高度稳定的胱氨酸结肽，以特异性和高亲和力（3-6 nM）结合整联蛋白αvβ6。结合剂不与相关整合素αvβ5、整合素α5β1或肿瘤血管生成相关整合素αvβ3交叉反应。正电子发射断层扫描显示，这些二硫键稳定的肽在表达整合素αvβ6的肿瘤中迅速积聚。在放射性示踪剂注射后1小时内，达到了7.7 ± 2.4至11.3 ± 3.0的临床相关肿瘤-肌肉比。通过在具有不同氨基酸含量的各种天然和药代动力学稳定的胱氨酸结支架中重新格式化αvβ6结合活性，实现脱靶给药的最小化。我们证明了肽支架的一级序列指导其药代动力学。具有高精氨酸或谷氨酸含量的支架遭受> 75%注射剂量/克（%ID/g）的高肾滞留。用肾清除的氨基酸，特别是丝氨酸取代这些氨基酸，导致注射后1小时肾蓄积显著降低<20%ID/g（p < 0.05，n=3）。我们已经设计了高度稳定的胱氨酸结肽，具有有效和特异性的整合素αvβ6结合活性，用于癌症检测。支架一级序列的药代动力学工程导致脱靶放射性示踪剂累积的显著减少。结合亲和力、特异性、稳定性和药代动力学的优化将促进用于癌症分子成像的胱氨酸结的翻译。
Detection of pancreatic cancer remains high priority and effective diagnostic tools are needed for clinical applications. Many cancer cells overexpress integrin αvβ6, a cell surface receptor being evaluated as a novel clinical biomarker. To validate this molecular target, several highly stable cystine knot peptides were engineered by directed evolution to bind specifically and with high-affinity (3-6 nM) to integrin αvβ6. The binders don’t cross-react with related integrin αvβ5, integrin α5β1 or tumor-angiogenesis associated integrin, αvβ3. Positron emission tomography showed that these disulfide-stabilized peptides rapidly accumulate at tumors expressing integrin αvβ6. Clinically relevant tumor-to-muscle ratios of 7.7 ± 2.4 to 11.3 ± 3.0 were achieved within one hour after radiotracer injection. Minimization of off-target dosing was achieved by reformatting αvβ6-binding activities across various natural and pharmacokinetically-stabilized cystine knot scaffolds with different amino acid content. We demonstrate that a peptide scaffold’s primary sequence directs its pharmacokinetics. Scaffolds with high arginine or glutamic acid content suffered high renal retention of > 75 percent injected dose per gram (%ID/g). Substitution of these amino acids with renally-cleared amino acids, notably serine, led to significant decreases in renal accumulation of < 20 %ID/g 1h post injection (p < 0.05, n=3). We have engineered highly stable cystine knot peptides with potent and specific integrin αvβ6 binding activities for cancer detection. Pharmacokinetic engineering of scaffold primary sequence led to significant decreases in off-target radiotracer accumulation. Optimization of binding affinity, specificity, stability and pharmacokinetics will facilitate translation of cystine knots for cancer molecular imaging.