Endogenous immunity at the forefront of tumor dormancy

Tumor-Derived Antigenic Peptides as Potential Cancer Vaccines

Peptide antigens derived from tumors have been observed to elicit protective immune responses, categorized as either tumor-associated antigens (TAAs) or tumor-specific antigens (TSAs). Subunit cancer vaccines incorporating these antigens have shown promise in inducing protective immune responses, leading to cancer prevention or eradication. Over recent years, peptide-based cancer vaccines have gained popularity as a treatment modality and are often combined with other forms of cancer therapy. Several clinical trials have explored the safety and efficacy of peptide-based cancer vaccines, with promising outcomes. Advancements in techniques such as whole-exome sequencing, next-generation sequencing, and in silico methods have facilitated the identification of antigens, making it increasingly feasible. Furthermore, the development of novel delivery methods and a deeper understanding of tumor immune evasion mechanisms have heightened the interest in these vaccines among researchers. This article provides an overview of novel insights regarding advancements in the field of peptide-based vaccines as a promising therapeutic avenue for cancer treatment. It summarizes existing computational methods for tumor neoantigen prediction, ongoing clinical trials involving peptide-based cancer vaccines, and recent studies on human vaccination experiments.

Local and distant tumor dormancy during early stage breast cancer are associated with the predominance of infiltrating T effector subsets

Background

Although breast cancer mortality is a result of distant recurrences associated with the establishment of tumor dormancy, current clinical practice guidelines recommend a wait and watch approach for tumor recurrences. This is because of our limited understanding of tumor dormancy and insufficient evidence in support of immunological control of tumor dormancy.

Methods

We used FVBN202 transgenic mice expressing rat neu oncogene in the mammary glands, and their parental FVB strain lacking neu expression. These models allowed the detection of tumor dormancy at distant sites using the rat neu protein as a tumor marker. We also used Ki67 for the detection of the indolent and quiescent types of tumor dormancy. Multicolor flow cytometry was used to detect dormant tumor cells and T cell subsets. Co-culture studies were performed to determine the role of T cells in preventing regrowth of dormant cells.

Results

We demonstrated that dormant tumor cells were present at the site of primary breast cancer and at distant sites in the lungs and in the liver very early in the course of early stage breast cancer when no distant metastasis was evident. Dormant tumor cells were characterized as neu expressing Ki67⁻ and Ki67^low fractions associated with the induction of local immune responses predominated by CD4+ and CD8+ T effector cell subsets. The presence of neu-autoreactive T cells from FVBN202 mice only prevented regrowth of dormant cells. On the other hand, presence of neu-alloreactive anti-tumor T cells in FVB mice prior to tumor challenge resulted in the protection of mice from the dissemination of dormant tumor cells to distant organs.

Conclusion

Our results suggest that immunotherapeutic targeting of semi-allogeneic mutant neoantigens during tumor dormancy might prevent distant recurrence of the disease.