Immunotherapy and radiation

Target-Based Radiosensitization Strategies: Concepts and Companion Animal Model Outlook

External beam radiotherapy is indicated in approximately 50-60% of human cancer patients. The prescribed dose of ionizing radiation that can be delivered to a tumor is determined by the sensitivity of the normal surrounding tissues. Despite dose intensification provided by highly conformal radiotherapy, durable locoregional tumor control remains a clinical barrier for recalcitrant tumor histologies, and contributes to cancer morbidity and mortality. Development of target-based radiosensitization strategies that selectively sensitizes tumor tissue to ionizing radiation is expected to improve radiotherapy efficacy. While exploration of radiosensitization strategies has vastly expanded with technological advances permitting the precise and conformal delivery of radiation, maximal clinical benefit derived from radiotherapy will require complementary discoveries that exploit molecularly-based vulnerabilities of tumor cells, as well as the assessment of investigational radiotherapy strategies in animal models that faithfully recapitulate radiobiologic responses of human cancers. To address these requirements, the purpose of this review is to underscore current and emerging concepts of molecularly targeted radiosensitizing strategies and highlight the utility of companion animal models for improving the predictive value of radiotherapy investigations.

Combined Radionuclide Therapy and Immunotherapy for Treatment of Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of the disease with poor clinical outcomes and limited therapeutic options. Immune checkpoint blockade (CP) has surged to the forefront of cancer therapies with widespread clinical success in a variety of cancer types. However, the percentage of TNBC patients that benefit from CP as a monotherapy is low, and clinical trials have shown the need for combined therapeutic modalities. Specifically, there has been interest in combining CP therapy with radiation therapy where clinical studies primarily with external beam have suggested their therapeutic synergy, contributing to the development of anti-tumor immunity. Here, we have developed a therapeutic platform combining radionuclide therapy (RT) and immunotherapy utilizing a radiolabeled biomolecule and CP in an E0771 murine TNBC tumor model. Survival studies show that while neither monotherapy is able to improve therapeutic outcomes, the combination of RT + CP extended overall survival. Histologic analysis showed that RT + CP increased necrotic tissue within the tumor and decreased levels of F4/80+ macrophages. Flow cytometry analysis of the peripheral blood also showed that RT + CP suppressed macrophages and myeloid-derived suppressive cells, both of which actively contribute to immune escape and tumor relapse.

Unexpected response with palliative conventional therapy in head and neck squamous cell carcinoma after anti-programmed death-1 progression

BACKGROUND

The application of anti-programmed death-1 (PD-1) therapies for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) has found promising results. It is the first "second-line therapy" in this setting to impact on prognosis. The studies demonstrated overall response rates in the range of 20%. Therefore, HNSCC showed 60%-80% progression at first evaluation with better overall survival, suggesting regained efficacy of treatments given thereafter.

METHODS

We report three clinical cases treated with anti-PD-1 after platinum-based chemotherapy.

RESULTS

Our case reports achieved an unforeseen response to conventional therapies supporting the hypothesis of restored responses to conventional therapies after immunotherapy.

CONCLUSIONS

We believe that the inhibition of the PD-1/PD-ligand 1 checkpoint may synergize with both chemotherapy or radiotherapy through immunologic interplay, reversing the HNSCC-induced immune suppression.

Immunotherapy with radiotherapy in urological malignancies

PURPOSE OF REVIEW

Radiotherapy has the potential to augment the host's immune response to cancer. Urological malignancies are highly immunogenic and the combination of radiotherapy and immunotherapy shows promise. In this review, we discuss the effects of radiotherapy on the cancer immune system and highlight the rationale for using the combined approach in prostate, urothelial and renal cancers. Current clinical studies are summarized emphasising the synergistic effects of the combination and the possibility of improved clinical outcomes.

RECENT FINDINGS

Local and abscopal effects have been observed in different urological cancers when using a combined approach. Large fraction size is associated with an increased immune response. Multiple radiotherapy/immunotherapy combinations are being studied in several clinical trials although no combination has yet been introduced in to standard practice.

SUMMARY

Although our knowledge of immunomodulation by radiotherapy has improved significantly in recent times, there remain several unanswered questions regarding how to best use the combination in clinical practice. Ongoing trials will provide further insight into complex mechanisms governing radiotherapy-immunotherapy interactions, with potential to improve clinical outcomes.

Optimizing tumor immune response through combination of radiation and immunotherapy

Radiation therapy and immunotherapy are two highly evolving modalities for the treatment of solid tumors. Immunotherapeutic drugs can either stimulate the immune system via immunogenic pathways or target co-inhibitory checkpoints. An augmented tumor cell recognition by host immune cells can be achieved post-irradiation, as irradiated tissues can release chemical signals which are sensed by the immune system resulting in its activation. Different strategies combining both treatment modalities were tested in order to achieve a better therapeutic response and longer tumor control. Both regimens act synergistically to one another with complimentary mechanisms. In this review, we explore the scientific basis behind such a combination, starting initially with a brief historical overview behind utilizing radiation and immunotherapies for solid tumors, followed by the different types of these two modalities, and the biological concept behind their synergistic effect. We also shed light on the common side effects and toxicities associated with radiation and immunotherapy. Finally, we discuss previous clinical trials tackling this multimodality combination and highlight future ongoing research.

Enhanced skin toxicity with concurrent ipilimumab and radiation in vaginal/vulvar melanoma: a case report and literature review

Ipilimumab is a monoclonal cytotoxic T-lymphocyte-associated protein 4 antibody that has demonstrated improved survival in cutaneous melanoma. Little is known about the clinical impact of combining anti-cytotoxic T-lymphocyteassociated protein 4 therapy with radiation. Here we report a case of severe cutaneous desquamation in a 70-year-old female with vaginal/vulvar melanoma receiving concurrent ipilimumab and radiation therapy. The toxicity was successfully treated with oral/topical steroids and a break from treatment. This case underscores the importance of future research on optimal strategies for combining radiation with novel anti-tumour agents.

Predictors of clinical response to immunotherapy with or without radiotherapy

Success with recent immunotherapies has resulted in previously unattainable response rates, as well as durable responses in diseases with historically poor prognoses. The combination of radiation therapy and immunotherapy has been a recent area of active investigation, with exciting results in a subset of patients. However, patient characteristics predictive of probable benefit from therapy and clinically meaningful biomarkers indicative of the early development of an antitumor immune response have yet to be identified. What is needed is a better way to predict which patients are likely to benefit from therapy, which would allow those patients unlikely to benefit from immunotherapy to be spared potentially futile therapies, thereby avoiding unnecessary risks of toxicity and costly treatment. Here, we summarize the early data on predictors of clinical response to immunotherapy, and to immunotherapy in combination with radiation.

Pembrolizumab for the treatment of melanoma

The immune system plays a vital role in regulating tumor growth, and the oncology community has witnessed an exciting resurgence in clinical research to develop effective immunotherapeutic strategies. The utility of these strategies in advanced melanoma has been at the forefront of these developments. In particular, blockade of programmed cell death protein 1 (PD-1) in advanced melanoma has proven to be a most promising new anticancer strategy. Pembrolizumab is a humanized IgG4 anti-PD-1 antibody that exerts its anti-tumor effect through blocking the interaction of the immune inhibitory molecule PD-1 with its ligands. Its effect has been most convincingly demonstrated in the setting of advanced melanoma, with growing evidence of clinical responses across a broad spectrum of other solid and hematological malignancies.