Scholarlink

Background <p>Immunostimulatory adjuvants used in vaccines to protect against infectious disease have demonstrated efficacy in stimulating anti-cancer immunity. The most advanced ones activate Toll-Like Receptor-4 (TLR4), a transmembrane signaling molecule expressed by macrophages and dendritic cells triggering innate immune responses. Lipopolysaccharide, the first identified TLR4 agonist, induces toxic, unregulated immune activation. Mimetics of monophosphoryl lipid A, the stimulatory component in lipopolysaccharide, reduced immunotoxicity while retaining immunostimulatory properties. Intratumoral injection of TLR4 agonists can stimulate in situ antitumor immune responses by recruitment of immune cells and production of inflammatory cytokines mediating antitumor effects via various mechanisms – including direct cancer cell death and recruitment of effector cells. Clinical trials in humans showed intratumoral TLR4 agonist injection augmented cytotoxicity – both locally and through abscopal mechanisms.</p> Methods <p>We considered whether intratumoral administration of TLR4 agonist EmT4™ in a canine soft tissue sarcoma (STS) could improve the surgical outcome by in situ immunostimulation prior to tumor removal. A 3-cm soft tissue mass on the right forelimb of an 8-year-old female spayed Boston terrier was given two intratumoral injections of EmT4™ two weeks apart, authorized by the owner. The tumor was excised 4-weeks after the second injection. Histopathology, immunohistochemistry, and in situ RNA hybridization were utilized to explore immune cell populations in the tumor microenvironment.</p> Results <p>There was transient lethargy only on the day of the first injection that resolved within hours. Histopathology revealed grade 2 STS with large numbers of densely packed perivascular immune cells disseminated within the tumor. Immunohistochemistry for immune cell markers showed heterogeneous positive staining within cell clusters – CD3 (25%), CD20 (57%), FOXP3 (8%), CD204 (5%), and Iba-1 (36%). In situ hybridization performed on serial STS sections identified transcripts in cells for CD4 (29%), TNF-α (24%), CD8 (3.2%), and interferon-γ (1.3%) in lymphocyte clusters.</p> Conclusions <p>EmT4™ may have initiated an innate immune response that attracted and activated immune effector cells intratumorally. Follow up investigations and clinical trials including dogs with pretreatment biopsies are essential to be certain of appropriate EmT4™ dosing, toxicities, and repeatability of the observations described here before its clinical usage. This case is foundational to those efforts.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Preliminary immunologic observations of intratumoral EmT4™, a TLR4 agonist, in a canine soft tissue sarcoma

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年8月1日

查看全文
  • Stuart C. Helfand,
  • Mariano Carossino,
  • Jiho Kim,
  • David R. McMonigle Jr,
  • Darrick Carter,
  • Sean A. Gray

摘要

Background

Immunostimulatory adjuvants used in vaccines to protect against infectious disease have demonstrated efficacy in stimulating anti-cancer immunity. The most advanced ones activate Toll-Like Receptor-4 (TLR4), a transmembrane signaling molecule expressed by macrophages and dendritic cells triggering innate immune responses. Lipopolysaccharide, the first identified TLR4 agonist, induces toxic, unregulated immune activation. Mimetics of monophosphoryl lipid A, the stimulatory component in lipopolysaccharide, reduced immunotoxicity while retaining immunostimulatory properties. Intratumoral injection of TLR4 agonists can stimulate in situ antitumor immune responses by recruitment of immune cells and production of inflammatory cytokines mediating antitumor effects via various mechanisms – including direct cancer cell death and recruitment of effector cells. Clinical trials in humans showed intratumoral TLR4 agonist injection augmented cytotoxicity – both locally and through abscopal mechanisms.

Methods

We considered whether intratumoral administration of TLR4 agonist EmT4™ in a canine soft tissue sarcoma (STS) could improve the surgical outcome by in situ immunostimulation prior to tumor removal. A 3-cm soft tissue mass on the right forelimb of an 8-year-old female spayed Boston terrier was given two intratumoral injections of EmT4™ two weeks apart, authorized by the owner. The tumor was excised 4-weeks after the second injection. Histopathology, immunohistochemistry, and in situ RNA hybridization were utilized to explore immune cell populations in the tumor microenvironment.

Results

There was transient lethargy only on the day of the first injection that resolved within hours. Histopathology revealed grade 2 STS with large numbers of densely packed perivascular immune cells disseminated within the tumor. Immunohistochemistry for immune cell markers showed heterogeneous positive staining within cell clusters – CD3 (25%), CD20 (57%), FOXP3 (8%), CD204 (5%), and Iba-1 (36%). In situ hybridization performed on serial STS sections identified transcripts in cells for CD4 (29%), TNF-α (24%), CD8 (3.2%), and interferon-γ (1.3%) in lymphocyte clusters.

Conclusions

EmT4™ may have initiated an innate immune response that attracted and activated immune effector cells intratumorally. Follow up investigations and clinical trials including dogs with pretreatment biopsies are essential to be certain of appropriate EmT4™ dosing, toxicities, and repeatability of the observations described here before its clinical usage. This case is foundational to those efforts.