MHC-restricted phosphopeptide antigens: preclinical validation and first-in-humans clinical trial in participants with high-risk melanoma
MHC-restricted phosphopeptide antigens: preclinical validation and first-in-humans clinical trial in participants with high-risk melanoma
复制标题
DOI：
10.1136/jitc-2019-000262
复制
发表时间：
2020-01-01
影响因子：
10.9
通讯作者：
Slingluff, Craig L., Jr.
中科院分区：
文献类型：
--
作者：
Engelhard, Victor H.;Obeng, Rebecca C.;Slingluff, Craig L., Jr.
MHC分子呈递的磷酸化肽是一类在癌细胞上表达并被CD8 t细胞识别的新抗原。这些肽是癌症免疫治疗的有希望的靶点。先前的研究发现，来自胰岛素受体底物2 （pIRS2）的HLA-A*0201限制性磷酸肽是一个这样的靶点。本研究的目的是表征来自乳腺癌抗雌激素抗性3 （BCAR3）的第二种磷酸化肽，并评估包含这两种磷酸化肽的新型免疫治疗疫苗的安全性和免疫原性。方法采用Western blot检测黑色素瘤和乳腺癌细胞系中BCAR3磷酸化蛋白的表达，采用（51）Cr释放法和细胞内细胞因子染色检测特异性t细胞对HLA-A*0201限制磷酸化BCAR3肽（pBCAR3(126-134)）的识别。用质谱法测定了人肿瘤外植体中pIRS2和pBCAR3肽的表达。在临床试验中，切除的IIA-IV期黑色素瘤患者在12周内接种了6次不完全弗氏佐剂和Hiltonol （poly-ICLC）中的一种或两种肽。不良事件（ae）根据美国国家癌症研究所（NCI）不良事件通用术语标准（CTCAE） V.4.03进行编码，并规定如果剂量限制性毒性（DLT）率超过33%，则早期终止研究。入组目标为12名参与者，可评估对每种肽的免疫反应。采用干扰素- γ ELISpot法检测t细胞反应。结果pBCAR3肽在小鼠体内和正常供体体外均具有免疫原性，并且pBCAR3特异性t细胞（126-134）控制肿瘤异种移植物的生长。用质谱法从人肝癌肿瘤中鉴定出pIRS2（1097-1105）肽。在临床试验中，15名参与者被招募。所有患者均有1级或2级治疗相关不良事件，但研究中没有3-4级不良事件、dlt或死亡。5/12患者的pIRS2（1097-1105）肽诱导t细胞应答（42%,90% CI 18% - 68%）， 2/12患者的pBCAR3（126-134）肽诱导t细胞应答（17%,90% CI 3% - 44%）。结论本研究支持含有肿瘤相关磷酸肽pBCAR3（126-134）和pIRS2（1097-1105）的疫苗的安全性和免疫原性，数据支持针对磷酸肽的免疫治疗的持续发展。未来的研究将确定进一步增强磷酸化肽特异性免疫反应的强度和持久性的方法。
Background Phosphorylated peptides presented by MHC molecules represent a new class of neoantigens expressed on cancer cells and recognized by CD8 T-cells. These peptides are promising targets for cancer immunotherapy. Previous work identified an HLA-A*0201-restricted phosphopeptide from insulin receptor substrate 2 (pIRS2) as one such target. The purpose of this study was to characterize a second phosphopeptide, from breast cancer antiestrogen resistance 3 (BCAR3), and to evaluate safety and immunogenicity of a novel immunotherapic vaccine comprising either or both of these phosphorylated peptides.Methods Phosphorylated BCAR3 protein was evaluated in melanoma and breast cancer cell lines by Western blot, and recognition by T-cells specific for HLA-A*0201-restricted phosphorylated BCAR3 peptide (pBCAR3(126-134)) was determined by(51)Cr release assay and intracellular cytokine staining. Human tumor explants were also evaluated by mass spectrometry for presentation of pIRS2 and pBCAR3 peptides. For the clinical trial, participants with resected stage IIA-IV melanoma were vaccinated 6 times over 12 weeks with one or both peptides in incomplete Freund's adjuvant and Hiltonol (poly-ICLC). Adverse events (AEs) were coded based on National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) V.4.03, with provision for early study termination if dose-limiting toxicity (DLT) rates exceeded 33%. The enrollment target was 12 participants evaluable for immune response to each peptide. T-cell responses were assessed by interferon-gamma ELISpot assay.Results pBCAR3 peptides were immunogenic in vivo in mice, and in vitro in normal human donors, and T-cells specific for pBCAR3(126-134)controlled outgrowth of a tumor xenograft. The pIRS2(1097-1105)peptide was identified by mass spectrometry from human hepatocellular carcinoma tumors. In the clinical trial, 15 participants were enrolled. All had grade 1 or 2 treatment-related AEs, but there were no grade 3-4 AEs, DLTs or deaths on study. T-cell responses were induced to the pIRS2(1097-1105)peptide in 5/12 patients (42%, 90% CI 18% to 68%) and to the pBCAR3(126-134)peptide in 2/12 patients (17%, 90% CI 3% to 44%).Conclusion This study supports the safety and immunogenicity of vaccines containing the cancer-associated phosphopeptides pBCAR3(126-134)and pIRS2(1097-1105), and the data support continued development of immune therapy targeting phosphopeptides. Future studies will define ways to further enhance the magnitude and durability of phosphopeptide-specific immune responses.