DNA疫苗治疗HER2阳性晚期乳腺癌

　　既往研究结果表明，对于HER2阳性乳腺癌，给予曲妥珠单抗治疗后，外周血液HER2特异性1型T淋巴细胞水平较高与较低的患者相比，临床结局显著较好；不过，只有少数患者在治疗后产生可测量的HER2免疫力。为此，美国华盛顿大学医学癌症疫苗研究所设计出一种编码HER2细胞内结构域的质粒DNA疫苗，可以提高HER2特异性T淋巴细胞水平。那么，这种治疗型疫苗对于HER2阳性乳腺癌患者是否安全？能否诱导产生HER2特异性免疫力？

　　2022年11月3日，《美国医学会杂志》肿瘤学分册在线发表美国华盛顿大学医学癌症疫苗研究所和弗雷德·哈钦森癌症中心的研究报告，首次探讨了3种剂量（10、100、500微克）HER2细胞内结构域编码质粒DNA疫苗对HER2阳性晚期乳腺癌患者的安全性和免疫原性。

NCT00436254: Vaccine Therapy With Sargramostim (GM-CSF) in Treating Patients With HER2 Positive Stage III-IV Breast Cancer or Ovarian Cancer (A Phase I Study of a DNA Plasmid Based Vaccine Encoding the HER-2/Neu Intracellular Domain in Subjects With HER2/Neu Overexpressing Tumors)

　　该单中心非随机对照一期临床试验于2001年10月～2010年3月从弗雷德·哈钦森癌症中心入组HER2阳性III～IV期乳腺癌完成标准治疗患者66例，中位年龄51岁，范围34～77岁，入组前30天未接受化疗或免疫抑制药物，左心室射血分数正常，平均分为3组，分别皮内注射3种剂量（10、100、500微克）HER2细胞内结构域编码质粒DNA疫苗，同时给予可溶性粒细胞-巨噬细胞集落刺激因子作为佐剂，每月1次，共计3次。随后10年定期并每年进行随访，评定毒性反应，收集外周血液单核细胞用于免疫评价。第16周和第36周对疫苗接种部位进行活检，测定DNA的持久性。2012年1月～2013年3月和2021年7月～2022年8月进行数据分析，根据不良事件通用术语标准3.0版对安全性进行分级，采用γ干扰素酶联免疫吸附斑点测定HER2细胞内结构域免疫反应。次要目标确定疫苗剂量是否与免疫力相关，并评价疫苗接种部位质粒DNA的持久性。

　　结果，大多数与疫苗相关的毒性反应为1级和2级，各剂量组相比无显著差异。

　　对分组、研究周数、基线细胞内结构域反应、入组时年龄、曲妥珠单抗疗程、既往化疗方案数量、入组后第一年复发等其他影响因素进行校正后，在大多数时间点，第2组100微克和第3组500微克与第1组10微克患者相比，HER2细胞内结构域1型免疫应答水平较高：

• 第2组与第1组相比：高181倍（95%置信区间：60～303，P=0.003）
• 第3组与第1组相比：高233倍（95%置信区间：102～363，P<0.001）

　　16周时DNA持续存在与未持续存在的患者相比，疫苗接种结束后各个时间点的HER2细胞内结构域免疫力平均水平显著较低。疫苗剂量最高组患者疫苗注射部位DNA持续存在率最高。

　　此外，第2组与第1组和第3组相比，总生存和无进展生存有获益趋势。

　　因此，该非随机对照一期临床试验结果表明，对于大多数HER2阳性乳腺癌患者，100微克剂量HER2胞内结构域质粒疫苗接种后可产生HER2特异性1型T淋巴细胞，该免疫力在疫苗接种结束后仍然存在，持久免疫力与疫苗注射部位DNA水平成反比。目前，随机对照二期临床试验正在对此开展进一步评价。

JAMA Oncol. 2022 Nov 3. IF: 33.006

Safety and Outcomes of a Plasmid DNA Vaccine Encoding the ERBB2 Intracellular Domain in Patients With Advanced-Stage ERBB2-Positive Breast Cancer: A Phase 1 Nonrandomized Clinical Trial.

Disis MLN, Guthrie KA, Liu Y, Coveler AL, Higgins DM, Childs JS, Dang Y, Salazar LG.

University of Washington Medicine Cancer Vaccine Institute, University of Washington, Seattle; Fred Hutchinson Cancer Center, Seattle, Washington.

This phase 1 nonrandomized clinical trial assesses the safety and immunogenicity of 3 doses (10, 100, and 500 μg) of a plasmid-based vaccine encoding the ERBB2 intracellular domain in patients with advanced-stage ERBB2-positive breast cancer.

QUESTION: Can a plasmid DNA vaccine, encoding the ERBB2 intracellular domain (ICD), be administered safely and generate dose-dependent ERBB2-specific immunity?

FINDINGS: In this phase 1 nonrandomized clinical trial of 66 patients with advanced-stage ERBB2-positive breast cancer, a majority grade 1/2 adverse events were generated for all doses. Patients in arms 2 (100 μg) and 3 (500 μg) had higher magnitude ICD T-cell levels than those in arm 1 (10 μg); immunity waned with DNA persistence at the injection site, with highest incidence in arm 3.

MEANING: Findings showed that 100 μg of ERBB2 ICD plasmid DNA was associated with generation of immunity in most patients, which persisted after the end of vaccinations; enduring immunity was adversely associated with DNA retention at the injection site.

IMPORTANCE: High levels of ERBB2 (formerly HER2)-specific type 1 T cells in the peripheral blood are associated with favorable clinical outcomes after trastuzumab therapy; however, only a minority of patients develop measurable ERBB2 immunity after treatment. Vaccines designed to increase ERBB2-specific T-helper cells could induce ERBB2 immunity in a majority of patients.

OBJECTIVE: To determine the safety and immunogenicity of 3 doses (10, 100, and 500 μg) of a plasmid-based vaccine encoding the ERBB2 intracellular domain (ICD).

DESIGN, SETTING, AND PARTICIPANTS: Single-arm phase 1 trial including 66 patients with advanced-stage ERBB2-positive breast cancer treated in an academic medical center between 2001 and 2010 with 10-year postvaccine toxicity assessments. Data analysis was performed over 2 periods: January 2012 to March 2013 and July 2021 to August 2022.

INTERVENTIONS: Patients were sequentially enrolled to the 3 dose arms. The vaccine was administered intradermally once a month with soluble granulocyte-macrophage colony-stimulating factor as an adjuvant for 3 immunizations. Toxicity evaluations occurred at set intervals and yearly. Peripheral blood mononuclear cells were collected for evaluation of immunity. Biopsy of vaccine sites at weeks 16 and 36 measured DNA persistence.

MAIN OUTCOMES AND MEASURES: Safety was graded by Common Terminology Criteria for Adverse Events, version 3.0, and ERBB2 ICD immune responses were measured by interferon-γ enzyme-linked immunosorbent spot. Secondary objectives determined if vaccine dose was associated with immunity and evaluated persistence of plasmid DNA at the vaccine site.

RESULTS: A total of 66 patients (median [range] age, 51 [34-77] years) were enrolled. The majority of vaccine-related toxic effects were grade 1 and 2 and not significantly different between dose arms. Patients in arm 2 (100 μg) and arm 3 (500 μg) had higher magnitude ERBB2 ICD type 1 immune responses at most time points than arm 1 (10 μg) (arm 2 compared with arm 1, coefficient, 181 [95% CI, 60-303]; P=0.003; arm 3 compared with arm 1, coefficient, 233 [95% CI, 102-363]; P<0.001) after adjusting for baseline factors. ERBB2 ICD immunity at time points after the end of immunizations was significantly lower on average in patients with DNA persistence at week 16 compared with those without persistence. The highest vaccine dose was associated with the greatest incidence of persistent DNA at the injection site.

CONCLUSIONS AND RELEVANCE: In this phase 1 nonrandomized clinical trial, immunization with the 100-μg dose of the ERBB2 ICD plasmid-based vaccine was associated with generation of ERBB2-specific type 1 T cells in most patients with ERBB2-expressing breast cancer, and it is currently being evaluated in randomized phase 2 trials.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00436254

PMID: 36326756

DOI: 10.1001/jamaoncol.2022.5143