Lee Susan J, Levitsky Konstantin, Parlati Francesco, Bennett Mark K, Arastu-Kapur Shirin, Kellerman Lois, Woo Tina F, Wong Alvin F, Papadopoulos Kyriakos P, Niesvizky Ruben, Badros Ashraf Z, Vij Ravi, Jagannath Sundar, Siegel David, Wang Michael, Ahmann Gregory J, Kirk Christopher J
Onyx Pharmaceuticals, Inc., an Amgen subsidiary, South San Francisco, CA, USA.
South Texas Accelerated Research Therapeutics (START), San Antonio, TX, USA.
Br J Haematol. 2016 Jun;173(6):884-95. doi: 10.1111/bjh.14014. Epub 2016 Apr 12.
While proteasome inhibition is a validated therapeutic approach for multiple myeloma (MM), inhibition of individual constitutive proteasome (c20S) and immunoproteasome (i20S) subunits has not been fully explored owing to a lack of effective tools. We utilized the novel proteasome constitutive/immunoproteasome subunit enzyme-linked immunosorbent (ProCISE) assay to quantify proteasome subunit occupancy in samples from five phase I/II and II trials before and after treatment with the proteasome inhibitor carfilzomib. Following the first carfilzomib dose (15-56 mg/m(2) ), dose-dependent inhibition of c20S and i20S chymotrypsin-like active sites was observed [whole blood: ≥67%; peripheral blood mononuclear cells (PBMCs): ≥75%]. A similar inhibition profile was observed in bone marrow-derived CD138(+) tumour cells. Carfilzomib-induced proteasome inhibition was durable, with minimal recovery in PBMCs after 24 h but near-complete recovery between cycles. Importantly, the ProCISE assay can be used to quantify occupancy of individual c20S and i20S subunits. We observed a relationship between MM patient response (n = 29), carfilzomib dose and occupancy of multiple i20S subunits, where greater occupancy was associated with an increased likelihood of achieving a clinical response at higher doses. ProCISE represents a new tool for measuring proteasome inhibitor activity in clinical trials and relating drug action to patient outcomes.
虽然蛋白酶体抑制是治疗多发性骨髓瘤（MM）的一种有效方法，但由于缺乏有效的工具，对单个组成型蛋白酶体（c20S）和免疫蛋白酶体（i20S）亚基的抑制作用尚未得到充分研究。我们利用新型蛋白酶体组成型/免疫蛋白酶体亚基酶联免疫吸附（ProCISE）测定法，对来自五项I/II期和II期试验的样本在蛋白酶体抑制剂卡非佐米治疗前后的蛋白酶体亚基占有率进行定量分析。在首次给予卡非佐米剂量（15 - 56 mg/m²）后，观察到c20S和i20S类胰凝乳蛋白酶样活性位点的剂量依赖性抑制作用[全血：≥67%；外周血单核细胞（PBMC）：≥75%]。在骨髓来源的CD138⁺肿瘤细胞中也观察到了类似的抑制情况。卡非佐米诱导的蛋白酶体抑制作用持久，24小时后PBMC中的恢复最小，但在各周期之间接近完全恢复。重要的是，ProCISE测定法可用于定量单个c20S和i20S亚基的占有率。我们观察到MM患者反应（n = 29）、卡非佐米剂量与多个i20S亚基占有率之间的关系，其中占有率越高，在较高剂量下实现临床反应的可能性就越大。ProCISE代表了一种在临床试验中测量蛋白酶体抑制剂活性并将药物作用与患者预后相关联的新工具。
