目的:人乳头瘤病毒(HPV)阳性的头颈部鳞状细胞癌(HNSCC)在临床和免疫学上与HPV阴性的HNSCC不同。在这里,我们调查了肿瘤抗原HPVE6/E7和野生型p53特异性T细胞反应的存在,以及免疫检查点阻断对HPV阳性HNSCC患者的影响。
方法:用HPVE6/E7或野生型p53衍生肽混合物刺激HPV阳性HNSCC患者的外周血单核细胞(PBMC),并使用干扰素-γ酶联免疫吸附斑点测定法进行评估。进行流式细胞术以分析T细胞亚群和表达免疫检查点分子的T细胞的比例。
结果:23例患者中有22例(95.7%)检测到HPVE6/E7特异性T细胞,而20例患者中有3例(15.0%)检测到野生型p53特异性T细胞。16例患者中有7例(43.8%)表现出野生型p53特异性T细胞反应,使用完整的蛋白质而不是肽确定。免疫检查点阻断增强了20例患者中9例(45.0%)的野生型p53特异性T细胞应答。PBMC的流式细胞术分析显示,免疫检查点阻断后表现出增强的野生型p53特异性T细胞应答的应答者具有显著较高的Ki-67+CD4+T细胞比例,Ki-67+CD8+T细胞,调节性T细胞,PD-1+CD4+T细胞,和TIM-3+CD4+T细胞比非应答者。
结论:我们的研究结果表明,HPV阳性HNSCC患者的外周血中存在肿瘤抗原特异性T细胞。阻断检查点通路可以增强某些患者的T细胞反应,可能是通过激活的T细胞,Tregs,和/或耗尽的CD4+T细胞。
OBJECTIVE: Human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) is clinically and immunologically distinct from HPV-negative HNSCC. Herein, we investigated the presence of tumor antigens HPV E6/E7 and wild-type p53-specific T-cell responses, and the impact of immune checkpoint blockade in patients with HPV-positive HNSCC.
METHODS: Peripheral blood mononuclear cells (PBMCs) from patients with HPV-positive HNSCC were stimulated with HPV E6/E7 or wild-type p53-derived peptide mixture and evaluated using the interferon-γ enzyme-linked immunosorbent spot assay. Flow cytometry was performed to analyze the proportion of T-cell subsets and T cells expressing immune checkpoint molecules.
RESULTS: HPV E6/E7-specific T cells were detected in 22 (95.7%) of 23 patients, whereas wild-type p53-specific T cells were detected in 3 (15.0%) of 20 patients. Seven (43.8%) of 16 patients exhibited wild-type p53-specific T-cell responses, as determined using whole proteins instead of peptides. Immune checkpoint blockade enhanced wild-type p53-specific T-cell responses in 9 (45.0%) of 20 patients. Flow cytometric analysis of PBMCs revealed that responders exhibiting enhanced wild-type p53-specific T-cell responses following immune checkpoint blockade had a significantly higher proportion of Ki-67+CD4+ T cells, Ki-67+CD8+ T cells, regulatory T cells, PD-1+CD4+ T cells, and TIM-3+CD4+ T cells than non-responders.
CONCLUSIONS: Our findings indicate that tumor antigen-specific T cells are present in the peripheral blood of patients with HPV-positive HNSCC. Blockade of checkpoint pathways can enhance T-cell responses in certain patients, probably via activated T cells, Tregs, and/or exhausted CD4+ T cells.