Supplementary Material for: Intradermal naked DNA vaccination by DNA tattooing for mounting tumor-specific immunity in stage IV melanoma patients: a phase I clinical trial

Introduction: Naked DNA vaccination could be a powerful and safe strategy to mount antigen-specific cellular immunity. We designed a phase I clinical trial to investigate the toxicity of naked DNA vaccines encoding CD8+ T-cell epitope from tumor-associated antigen MART-1 in patients with advanced melanoma.

Methods: This dose escalating phase Ia clinical trial investigates the toxicity and immunological response upon naked DNA vaccines encoding a CD8+ T-cell epitope from the tumor-associated antigen MART-1, genetically linked to the gene encoding domain 1 of subunit-tetanus toxin fragment C in patients with advanced melanoma (inoperable stage IIIC-IV, AJCC 7th edition). The vaccine was administrated via intradermal application using a permanent make-up or tattoo device. Safety was monitored according to CTCAE v.3.0 and skin biopsies and blood samples were obtained for immunologic monitoring.

Results: Nine pretreated, HLA-A*0201-positive patients with advanced melanoma expressing MART-1 and MHC class I, with a good performance status, and adequate organ function, were included. With a median follow-up of 5.9 months, DNA vaccination was safe, without treatment-related deaths. Common treatment-emergent adverse events of any grade were dermatologic reactions at the vaccination site (100%) and pain (56%). One patient experienced grade 4 toxicity, most likely related to tumor progression. One patient (11%) achieved stable disease, lasting 353 days. Immune analysis showed no increase in vaccine-induced T cell response in peripheral blood of five patients, but did show a MART-1 specific CD8+ T cell response at the tattoo administration site. The maximum dose administered was 2 mg due to lack of clinical activity.

Conclusion: We showed that the developed DNA vaccine, applied using a novel intradermal application strategy, can be administered safely. Further research with improved vaccine formats is required to show possible clinical benefit of DNA vaccination.

引言：裸DNA疫苗接种或许是诱导抗原特异性细胞免疫的高效且安全的策略。本研究设计了一项I期临床试验，旨在探究编码肿瘤相关抗原MART-1的CD8+ T细胞表位的裸DNA疫苗在晚期黑色素瘤患者中的毒性反应。
方法：本剂量爬坡型Ia期临床试验，旨在评估编码肿瘤相关抗原MART-1的CD8+ T细胞表位的裸DNA疫苗的毒性与免疫学应答。该疫苗经基因工程手段与编码破伤风毒素C亚单位结构域1的基因相连，受试对象为符合美国癌症联合委员会（American Joint Committee on Cancer, AJCC）第7版分期标准的不可手术切除的IIIC~IV期晚期黑色素瘤患者。疫苗采用永久化妆或纹身设备经皮内途径给药。安全性依据不良事件通用术语标准（Common Terminology Criteria for Adverse Events, CTCAE）v3.0进行监测，并采集皮肤活检标本与血液样本用于免疫学监测。
结果：本研究共纳入9例经前期治疗的、HLA-A*0201基因型阳性的晚期黑色素瘤患者，此类患者均表达MART-1与主要组织相容性复合体I类分子（Major Histocompatibility Complex class I, MHC class I），且体能状态良好、器官功能充足。中位随访时长为5.9个月，结果显示DNA疫苗接种安全性良好，未出现与治疗相关的死亡事件。各等级常见治疗突发不良事件包括接种部位皮肤反应（100%）与疼痛（56%）。1例患者出现4级毒性反应，极有可能与肿瘤进展相关。1例患者（11%）达到疾病稳定，持续时长达353天。免疫学分析显示，5例患者的外周血中未检测到疫苗诱导的T细胞应答，但在纹身给药部位检测到MART-1特异性CD8+ T细胞应答。由于未观察到临床活性，最高给药剂量设定为2 mg。
结论：本研究证实，采用新型皮内给药策略的DNA疫苗可安全给药。未来需开展针对优化疫苗剂型的进一步研究，以验证DNA疫苗接种可能带来的临床获益。