Active specific immunotherapy with MN\CA IX antigen peptide vaccines for renal cell carcinoma

MN/CAIX抗原是一种肿瘤相关抗原，约90%的肾细胞癌(RCQ)表达。我们合成了9个与人类白细胞抗原A24结合的抗原肽，并将其作为肿瘤疫苗在小鼠同基因ROC模型中诱导该抗原特异性反应。用MN/CA99多肽疫苗免疫小鼠，诱导抗原特异性CTL。提示MN/CA9抗原肽疫苗可能是治疗肾癌的潜在途径。我们还研究了肾癌患者淋巴细胞体外诱导CTL的能力。此外，用转移性肾癌患者的PBMC检测CTL前体细胞的存在。自体树突状细胞负载MN/CA9多肽刺激患者淋巴细胞产生抗原特异性CTL，基于这些临床资料，我们从2002年7月开始研究MN/CA9多肽疫苗皮下注射治疗播散性肾癌的I期研究。远处转移的患者每隔2周接种3套MN/CA9 9肽疫苗6次。本研究的主要目的是评价这些抗原肽疫苗的毒性和免疫原性。到目前为止，有6名患者完成了该方案，仅观察到发热、瘙痒和局部反应(肿胀、疼痛)等轻微毒性。部分患者可诱导抗原特异性细胞毒作用。此外，还检测了部分患者的MN/CA9多肽疫苗抗体(IgG)。这些结果表明，我们的MN/CA9多肽疫苗可能是安全的，适用于HLA-A24阳性的肾癌患者。此外，我们目前正在研究改进的多肽疫苗的生成，以获得更强的抗原性。

MN/CA IX antigen is a tumor-associated antigen expressed in approximately 90 % of renal cell carcinomas (RCQ). We have synthesized 9mer antigen peptides restricted to HLA-A24 and employed them as tumor vaccines to investigate the ability to induce this antigen specific responses in mouse syngeneic ROC model. Antigen specific CTL was induced by immunization of MN/CA9 9mer peptide vaccine in mouse system. This finding suggests that vaccination with MN/CA9 antigen peptides may be potential therapeutic approach for RCC patients. We also have investigated the capacity of CTL induction using RCC patient lymphocytes in vitro. In addition, presence of CTL precursor was investigated using PBMC from the patients with metastatic RCC patients. Stimulation of patient lymphocytes with autologons dendritic cell loaded MN/CA9 peptides resulted in antigen specific CTL induction.Based on these pie-clinical data, we started a phase-I study to investigate MN/CA9 peptide vaccines by subcutaneous administration in patients with disseminated renal cell carcinoma since July 2002. Patients with distant metastases received three sets of MN/CA9 9-mer peptide vaccines 6 times at 2-week intervals. Primary end points of this study are to evaluate the toxicity and immunogenicity of these antigen peptide vaccines. Six patients finished the protocol until now and only low grade toxicities such as fever, pruritus and local reaction (swelling, pain) were observed. Antigen specific cell-mediated cytotoxicity was induced in some patients. In addition, antibodies (IgG) against MN/CA9 peptides vaccines were detected in some patients. These findings suggest that our MN/CA9 peptide vaccines may be safe and applicable for HLA-A24 positive RCC patients. Moreover; we are currently investigating the generation of modified peptide vaccines to obtain more powerful antigenicity.