Detection of Immunogenic Cell Death in Tumor Vaccination Mouse Model

Immunogenic cell death (ICD) is a form of regulated cell death that is capable of eliciting an immune response. In cancer, tumor cells undergoing ICD are known to emit damage associated molecular patterns (DAMPs) that are capable of recruiting and activating antigen presenting cells (APCs), which ultimately lead to the activation of an antitumor immune response. Surface translocation of intracellular chaperones such as calreticulin, release of TLR agonists such as high mobility box 1, and the secretion of type I IFN are some of the hallmark features seen in tumors succumbing to ICD. While detection of these molecules is suggestive of ICD induction, which alone does not certify that the treatment is an ICD inducer, an in vivo vaccination assay using injured tumor cells remains to be the gold standard method to functionally verify ICD. This chapter will discuss the necessary steps required to conduct an in vivo vaccination assay, focusing on the preparation of vaccine using treated tumor cells, and how these cells are then utilized in the animal model.

Clinical Data on Immunotherapy in Breast Cancer

BACKGROUND

Breast cancer has traditionally been considered to have a low immunogenic potential compared to other tumor entities.

SUMMARY

The most extensively studied immunotherapeutic agents for breast cancer to date are immune checkpoint inhibitors, with the results of the IMpassion130 trial leading to the approval of atezolizumab plus nab-paclitaxel for first-line treatment of programmed cell death ligand 1-positive, metastatic, triple-negative breast cancer, and studies in earlier stages have yielded promising results. Other immunotherapeutic options being assessed in phases 2 and 3 trials include vaccine-based therapies and treatment with anti-human epidermal growth factor receptor 2 (H-directed immune-linked antibodies) and substances evaluated in early clinical trials as cellular therapies (adoptive cell therapy and chimeric antigen receptor T cells).

KEY MESSAGES

Immunotherapy is an emerging modality for the treatment of breast cancer, as evidenced by the plethora of preclinical and clinical concepts and ongoing trials. Early studies established the role of immunotherapeutic agents in the metastatic setting. Ongoing studies will expand our knowledge about the timing of administration, best partners for combination therapy, and predictive biomarkers to guide immunotherapy for breast cancer.

Mechanisms of measles virus oncolytic immunotherapy

The study of measles virus (MeV) as a cancer immunotherapeutic was prompted by clinical observations of leukemia and lymphoma regressions in patients following measles virus infection in the 1970s and 1980s. Since then, numerous preclinical studies have confirmed the oncolytic activity of MeV vaccine strains as well as their potential to promote long-lasting tumor-specific immune responses. Early clinical data indicate that some of these effects may translate to the treatment of cancer patients. In this review, we provide a structured summary of current evidence for the anti-tumor immune activity of oncolytic MeV. We start with an overview of MeV oncolysis and MeV-induced immunogenic cell death. Next, we relate findings on MeV-mediated activation of antigen-presenting cells, T cell priming and effector mechanisms to the cancer immunity cycle. We discuss additional factors in the tumor microenvironment which are modulated by MeV treatment as well as the role of anti-viral immunity. Based on these findings, we highlight avenues for rational enhancement of oncolytic MeV immunotherapy by vector engineering. We further point to advantages and drawbacks of experimental models and propose areas warranting promising research. Lastly, we review the available immunomonitoring data from several Phase I clinical trials. While this review presents data for MeV, the concepts and principles introduced herein apply to other oncolytic viruses, providing a framework to assess novel cancer immunotherapies.

[New treatment options for iridociliary tumors]

BACKGROUND

Benign iridal tumors rarely necessitate a therapeutic intervention. In contrast, malignant tumors of the iris can threaten the patient's life and eyesight and require early treatment to prevent the development of metastases.

OBJECTIVE

Presentation of current treatment options for iridal tumors with special emphasis on iridal melanoma.

METHODS

This article gives an overview of the current literature based on a PubMed search as well as own clinical experience.

RESULTS

Treatment options for iridal and ciliary body melanomas comprise radiotherapeutic and surgical (eyeball-sparing and non-sparing) approaches. The eyeball-sparing surgical procedure of choice is block excision. While local tumor control rates and metastasis rates of block excision and radiotherapy are comparable, there are distinct differences especially between the spectra of complications. New treatment procedures include immunomodulatory approaches and targeted therapies. Using checkpoint inhibitors, no convincing enhancement of overall survival could be demonstrated for metastatic iridal melanoma, as is the case for cutaneous melanoma. In contrast, tumor vaccination with the help of tumor RNA-laden patient-derived dendritic cells seems to be a promising option for a subgroup of high-risk patients. Targeted therapies aiming to suppress the MAPK and PI3K/Akt pathways could not achieve any improvement in patient survival.

CONCLUSION

For the primary treatment of iridal melanoma a surgical, eyeball-sparing approach and also when appropriate, radiotherapy can be recommended. In the future, eligible high-risk patients could profit from a tumor vaccination. To date, there is no effective systemic treatment for metastatic iridal melanoma.

Strategies for the identification of T cell-recognized tumor antigens in hematological malignancies for improved graft-versus-tumor responses after allogeneic blood and marrow transplantation

Allogeneic blood and marrow transplantation (allo-BMT) is an effective immunotherapeutic treatment that can provide partial or complete remission for patients with hematological malignancies. Mature donor T cells in the donor inoculum play a central role in mediating graft-versus-tumor (GVT) responses by destroying residual tumor cells that persist after conditioning regimens. Alloreactivity towards minor histocompatibility antigens (miHA), which are varied tissue-related self-peptides presented in the context of major histocompatibility complex (MHC) molecules on recipient cells, some of which may be shared on tumor cells, is a dominant factor for the development of GVT. Potentially, GVT can also be directed to tumor-associated antigens or tumor-specific antigens that are more specific to the tumor cells themselves. The full exploitation of allo-BMT, however, is greatly limited by the development of graft-versus-host disease (GVHD), which is mediated by the donor T cell response against the miHA expressed in the recipient's cells of the intestine, skin, and liver. Because of the significance of GVT and GVHD responses in determining the clinical outcome of patients, miHA and tumor antigens have been intensively studied, and one active immunotherapeutic approach to separate these two responses has been cancer vaccination after allo-BMT. The combination of these two strategies has an advantage over vaccination of the patient without allo-BMT because his or her immune system has already been exposed and rendered unresponsive to the tumor antigens. The conditioning for allo-BMT eliminates the patient's existing immune system, including regulatory elements, and provides a more permissive environment for the newly developing donor immune compartment to selectively target the malignant cells. Utilizing recent technological advances, the identities of many human miHA and tumor antigenic peptides have been defined and are currently being evaluated in clinical and basic immunological studies for their ability to produce effective T cell responses. The first step towards this goal is the identification of targetable tumor antigens. In this review, we will highlight some of the technologies currently used to identify tumor antigens and anti-tumor T cell clones in hematological malignancies.

Immune-mediated anti-neoplastic effect of intratumoral RSV envelope glycoprotein expression is related to apoptotic death of tumor cells but not to the size of syncytia

AIM: To promote the development of improved tumor vaccination strategies relying on the intratumoral expression of viral fusogenic membrane proteins, we elucidated whether the size of syncytia or the way tumor cells die has an effect on the therapeutic outcome.

METHODS: In two syngeneic subcutaneous murine colon cancer models we assessed the anti-neoplastic effect on vector-treated and contralateral untreated tumors.

RESULTS: Intratumoral injection of a replication-defective adenovirus encoding respiratory syncytial virus fusion protein (RSV-F) alone (Ad.RSV-F) or together with the attachment glycoprotein RSV-G (Ad.RSV-F/G) led to a significant growth reduction of the vector-treated and contralateral untreated tumors. The treatment response was associated with a strong tumor-specific CTL response and significantly improved survival with medians of 46 d and 44 d, respectively. Intratumoral injection of Ad.RSV-G or a soluble RSV-F encoding adenovirus (Ad.RSV-F_sol) had no significant anti-neoplastic effect. The median survival of these treatment groups and of Ad.Null-treated control animals was about 30 d.

CONCLUSION: Although in vitro transduction of colon cancer cell lines with Ad.RSV-F/G resulted in about 8-fold larger syncytia than with Ad.RSV-F, the in vivo outcome was not significantly different. Transduction of murine colon cancer cell lines with Ad.RSV-F or Ad.RSV-F/G caused apoptotic cell death, in contrast to transduction with Ad.RSV-G or Ad.RSV-F_sol, suggesting an importance of the mode of cell death. Overall, these findings provide insight into improved tumor vaccination strategies relying on the intratumoral expression of viral fusogenic membrane proteins.