Camacho Ximena, Machado Camila Longo, García María Fernanda, Gambini Juan Pablo, Banchero Agustina, Fernández Marcelo, Oddone Natalia, Bertolini Zanatta Daniela, Rosal Carolina, Buchpiguel Carlos Alberto, Chammas Roger, Riva Eloisa, Cabral Pablo
Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Oncology. 2017;92(4):229-242. doi: 10.1159/000452419. Epub 2017 Feb 15.
Rituximab was the first monoclonal antibody approved for the treatment of B-cell non-Hodgkin lymphoma (NHL) expressing CD20 antigen. This antibody has also the potential to be used as a specific fluorescent and radiolabel agent for targeting NHL.
To radiolabel rituximab with technetium-99m (99mTc) or Cy7 and evaluate both probes as potential imaging agents for NHL.
Rituximab was derivatized with the trifluoroacetyl hydrazino protected form of succinimidyl ester of HYNIC and radiolabeled with 99mTc. Radiochemical stability and in vitro cell assays were evaluated. Biodistribution and single-photon emission computed tomography/computed tomography (SPECT/CT) were performed. Raji cells were transfected with luciferase for bioluminescent NHL imaging up to 21 days. Rituximab was labeled with Cy7 for in vivo noninvasive fluorescence imaging up to 96 h.
Radiolabeling was carried out in a fast, reproducible, easy, and stable way with high radiochemical purity and did not interfere with epitope recognition. Biodistribution and SPECT/CT studies showed high liver and discrete tumor uptake. Bioluminescence and fluorescence studies helped us evaluate rituximab-Cy7 in Raji subcutaneous engraftment in BALB/c nude mice.
Our results support the potential use of rituximab labeled either with 99mTc or Cy7 as a molecular imaging tool for staging, restaging, and guiding surgical excision of tumors, which merits further evaluation.
利妥昔单抗是首个被批准用于治疗表达CD20抗原的B细胞非霍奇金淋巴瘤（NHL）的单克隆抗体。该抗体还具有用作靶向NHL的特异性荧光和放射性标记剂的潜力。
用99m锝（99mTc）或Cy7对利妥昔单抗进行放射性标记，并评估这两种探针作为NHL潜在成像剂的性能。
利妥昔单抗用HYNIC琥珀酰亚胺酯的三氟乙酰肼保护形式进行衍生化，并用99mTc进行放射性标记。评估放射化学稳定性和体外细胞试验。进行生物分布和单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）。用荧光素酶转染Raji细胞用于长达21天的生物发光NHL成像。利妥昔单抗用Cy7标记用于长达96小时的体内无创荧光成像。
放射性标记以快速、可重复、简便且稳定的方式进行，放射化学纯度高，且不干扰表位识别。生物分布和SPECT/CT研究显示肝脏摄取高且肿瘤摄取离散。生物发光和荧光研究有助于我们在BALB/c裸鼠的Raji皮下移植瘤中评估利妥昔单抗-Cy7。
我们的结果支持将用99mTc或Cy7标记的利妥昔单抗作为分子成像工具用于肿瘤分期、再分期和指导手术切除的潜在用途，这值得进一步评估。
