Dadachova Ekaterina, Revskaya E, Sesay M A, Damania H, Boucher R, Sellers R S, Howell R C, Burns L, Thornton G B, Natarajan A, Mirick G R, DeNardo S J, DeNardo G L, Casadevall A
Department of Nuclear Medicine, Department of Microbiology and Immunology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.
Cancer Biol Ther. 2008 Jul;7(7):1116-27. doi: 10.4161/cbt.7.7.6197. Epub 2008 Apr 28.
Currently there is no satisfactory treatment for metastatic melanoma. Radioimmunotherapy (RIT) uses the antigen-antibody interaction to deliver lethal radiation to target cells. Recently we established the feasibility of targeting melanin in tumors with 188-Rhenium ((188)Re)-labeled 6D2 mAb to melanin. Here we carried out pre-clinical development of (188)Re-6D2 to accrue information necessary for a Phase I trial in patients with metastatic melanoma.
TCEP proved to be effective in generating a sufficient number of -SH groups on 6D2 to ensure high radiolabeling yields with (188)Re and preserved its structural integrity. (188)Re-6D2 was quickly cleared from the blood with the half-life of approximately 5 hrs and from the body--with the half-life of 10 hr. The doses of 0.5, 1.0 and 1.5 mCi significantly (p < 0.05) slowed down A2058 tumor growth in nude mice, also causing release of melanin into the extracellular space which could provide additional target for repeated treatments. Transient effects of RIT on WBC and platelet counts resolved by Day 14 post-treatment.
Tris(2-Carboxyethyl) Phosphine Hydrochloride (TCEP) was evaluated as potential agent for generation of -SH groups on 6D2 mAb. TCEP-treated 6D2 mAb was radiolabeled with (188)Re and its radiochemical purity and stability was measured by ITLC and HPLC and its immunoreactivity--by melanin-binding ELISA. The pharmacokinetics, therapeutic efficacy and acute hematologic toxicity studies were performed in nude mice bearing lightly pigmented A2058 human metastatic melanoma tumors.
We have developed radiolabeling and quality control procedures for melanin-binding (188)Re-6D2 mAb which made possible currently an on-going Phase I clinical trial in patients with metastatic melanoma.
目前转移性黑色素瘤尚无令人满意的治疗方法。放射免疫疗法（RIT）利用抗原 - 抗体相互作用将致死性辐射传递至靶细胞。最近我们证实了用188 - 铼（（188）Re）标记的抗黑色素6D2单克隆抗体靶向肿瘤中黑色素的可行性。在此，我们开展了（188）Re - 6D2的临床前研究，以获取转移性黑色素瘤患者一期试验所需信息。
三（2 - 羧乙基）膦盐酸盐（TCEP）被证明能有效地在6D2上产生足够数量的 -SH基团，以确保与（188）Re的高放射性标记产率，并保持其结构完整性。（188）Re - 6D2从血液中快速清除，半衰期约为5小时，从体内清除的半衰期为10小时。0.5、1.0和1.5毫居里的剂量显著（p < 0.05）减缓了裸鼠体内A2058肿瘤的生长，还导致黑色素释放到细胞外空间，这可为重复治疗提供额外靶点。放射免疫疗法对白细胞和血小板计数的短暂影响在治疗后第14天得到缓解。
评估三（2 - 羧乙基）膦盐酸盐（TCEP）作为在6D2单克隆抗体上产生 -SH基团的潜在试剂。用（188）Re对经TCEP处理的6D2单克隆抗体进行放射性标记，并通过离子交换薄层层析（ITLC）和高效液相色谱（HPLC）测量其放射化学纯度和稳定性，通过黑色素结合酶联免疫吸附测定（ELISA）测量其免疫反应性。在携带轻度色素沉着的A2058人转移性黑色素瘤肿瘤的裸鼠中进行药代动力学、治疗效果和急性血液学毒性研究。
我们已开发出用于黑色素结合（188）Re - 6D2单克隆抗体的放射性标记和质量控制程序，这使得目前针对转移性黑色素瘤患者的一期临床试验成为可能。
