Department of Surgery and Bioengineering, Advanced Clinical Research Center, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokane-dai, Minato-city, Tokyo, 108-8639, Japan.
J Transl Med. 2010 Sep 16;8:84. doi: 10.1186/1479-5876-8-84.
The tumor associated antigen (TAA) gp100 was one of the first identified and has been used in clinical trials to treat melanoma patients. However, the gp100 epitope peptide restricted to HLA-A2402 has not been extensively examined clinically due to the ethnic variations. Since it is the most common HLA Class I allele in the Japanese population, we performed a phase I clinical trial of cancer vaccination using the HLA-A2402 gp100 peptide to treat patients with metastatic melanoma.
The phase I clinical protocol to test a HLA-A2402 gp100 peptide-based cancer vaccine was designed to evaluate safety as the primary endpoint and was approved by The University of Tokyo Institutional Review Board. Information related to the immunologic and antitumor responses were also collected as secondary endpoints. Patients that were HLA-A2402 positive with stage IV melanoma were enrolled according to the criteria set by the protocol and immunized with a vaccine consisting of epitope peptide (VYFFLPDHL, gp100-in4) emulsified with incomplete Freund's adjuvant (IFA) for the total of 4 times with two week intervals. Prior to each vaccination, peripheral blood mononuclear cells (PBMCs) were separated from the blood and stored at -80°C. The stored PBMCs were thawed and examined for the frequency of the peptide specific T lymphocytes by IFN-γ- ELISPOT and MHC-Dextramer assays.
No related adverse events greater than grade I were observed in the six patients enrolled in this study. No clinical responses were observed in the enrolled patients although vitiligo was observed after the vaccination in two patients. Promotion of peptide specific immune responses was observed in four patients with ELISPOT assay. Furthermore, a significant increase of CD8+ gp100-in4+ CTLs was observed in all patients using the MHC-Dextramer assay. Cytotoxic T lymphocytes (CTLs) clones specific to gp100-in4 were successfully established from the PBMC of some patients and these CTL clones were capable of lysing the melanoma cell line, 888 mel, which endogenously expresses HLA-restricted gp100-in4.
Our results suggest this HLA-restricted gp100-in4 peptide vaccination protocol was well-tolerated and can induce antigen-specific T-cell responses in multiple patients. Although no objective anti-tumor effects were observed, the effectiveness of this approach can be enhanced with the appropriate modifications.
肿瘤相关抗原（TAA）gp100 是最早被鉴定出来的抗原之一，并已被用于临床试验来治疗黑色素瘤患者。然而，由于种族差异，限制在 HLA-A2402 上的 gp100 表位肽并未在临床上广泛研究。由于它是日本人中最常见的 HLA I 类等位基因，我们进行了一项 I 期临床试验，使用 HLA-A2402 gp100 肽对转移性黑色素瘤患者进行癌症疫苗接种。
该 I 期临床试验方案旨在评估安全性作为主要终点，已获得东京大学机构审查委员会的批准。还收集了与免疫和抗肿瘤反应相关的信息作为次要终点。根据方案设定的标准，招募 HLA-A*2402 阳性、IV 期黑色素瘤患者，用含有表位肽（VYFFLPDHL，gp100-in4）的不完全弗氏佐剂（IFA）乳化的疫苗免疫 4 次，间隔 2 周。每次接种前，从血液中分离外周血单核细胞（PBMC）并在-80°C 下储存。解冻储存的 PBMC，通过 IFN-γ-ELISPOT 和 MHC-Dextramer 测定来检测肽特异性 T 淋巴细胞的频率。
在入组的 6 名患者中，未观察到大于 1 级的相关不良事件。尽管在两名患者接种后观察到白癜风，但入组患者未观察到临床反应。ELISPOT 检测显示，4 名患者的肽特异性免疫反应得到了促进。此外，使用 MHC-Dextramer 检测，所有患者的 CD8+ gp100-in4+ CTL 均显著增加。从一些患者的 PBMC 中成功建立了针对 gp100-in4 的特异性细胞毒性 T 淋巴细胞（CTL）克隆，这些 CTL 克隆能够裂解内源性表达 HLA 受限 gp100-in4 的黑色素瘤细胞系 888mel。
我们的结果表明，这种 HLA 受限的 gp100-in4 肽疫苗接种方案耐受性良好，并能在多名患者中诱导抗原特异性 T 细胞反应。尽管未观察到客观的抗肿瘤作用，但通过适当的修改可以增强这种方法的效果。
