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The enhanced understanding of immunology experienced over the last 5 decades afforded through the tools of molecular biology has recently translated into cancer immunotherapy becoming one of the most exciting and rapidly expanding fields. Human cancer immunotherapy is now recognized as one of the pillars of treatment alongside surgery, radiation, and chemotherapy. The field of veterinary cancer immunotherapy has also rapidly advanced in the last decade with a handful of commercially available products and a plethora of investigational cancer immunotherapies, which will hopefully expand our veterinary oncology treatment toolkit over time., Competing Interests: Disclosure Dr P.J. Bergman is a co-inventor on patent US7556805B2 and was the veterinary principal investigator for the canine melanoma vaccine Oncept which received USDA-CVB conditional licensure in 2007 and full licensure in December of 2009. He also receives a minority royalty stream payment., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The enhanced understanding of immunology experienced over the last 4 decades afforded through the tools of molecular biology has recently translated into cancer immunotherapy becoming one of the most exciting and rapidly expanding fields. Human cancer immunotherapy is now recognized as one of the pillars of treatment alongside surgery, radiation, and chemotherapy. The field of veterinary cancer immunotherapy has also rapidly advanced in the last decade with a handful of commercially available products and a plethora of investigational cancer immunotherapies that will hopefully expand the veterinary oncology treatment toolkit over time., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The ideal cancer immunotherapy agent should be able to discriminate between cancer and normal cells, be potent enough to kill small or large numbers of tumor cells, and be able to prevent recurrence of the tumor. Tumor immunology and immunotherapy are among the most exciting and rapidly expanding fields; cancer immunotherapy is now recognized as a pillar of treatment alongside traditional modalities. This article highlights approaches that seem to hold particular promise in human clinical trials and many that have been tested in veterinary medicine., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Tumor immunology and immunotherapy is one of the most exciting and rapidly expanding fields. The immune system is divided into 2 primary components: the innate immune response and the highly specific, but more slowly developing, adaptive or acquired immune response. Immune responses are separated by whether they are induced by exposure to a foreign antigen (active response) or transferred through serum or lymphocytes from an immunized individual (passive response). The ideal cancer immunotherapy agent should discriminate between cancer and normal cells (specificity), be potent enough to kill small or large numbers of tumor cells (sensitivity), and prevent recurrence of a tumor (durability)., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The veterinary oncology profession is uniquely able to contribute to the many advances that are imminent in immunotherapy. However, what works in a mouse will often not reflect the outcome in human patients with cancer. Therefore, comparative immunotherapy studies using veterinary patients may be better able to bridge murine and human studies. Many cancers in dogs and cats seem to be stronger models for their counterpart human tumors than presently available murine model systems. This author looks forward to the time when immunotherapy plays a significant role in the treatment and/or prevention of cancer in human and veterinary patients., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

With the tools of molecular biology and a greater understanding of mechanisms to harness the immune system, effective tumor immunotherapy is becoming a reality. This new class of therapeutics offers a more targeted, and therefore precise, approach to the treatment of cancer. The recent conditional licensure of a xenogeneic DNA vaccine for advanced canine malignant melanoma strongly suggests that immunotherapy can play an extremely important role alongside the classic cancer treatment triad components of surgery, radiation therapy, and chemotherapy.

Chemotherapy agents are extremely important in the treatment of liquid malignancies, such as lymphoma, myeloma, and chronic lymphocytic leukemia. In addition, chemotherapy agents have proven effective in the adjuvant treatment of solid tumors, such as osteosarcoma, hemangiosarcoma, transitional cell carcinoma, and others. Unfortunately, chemotherapy resistance in these situations is the most significant cause of treatment failure. Therefore, the ability to predict, treat, or circumvent resistance is extremely likely to improve clinical outcomes. This article has reviewed the most widely investigated forms of chemotherapy resistance, such as reduced drug accumulation, increased DNA damage repair, decreased apoptosis, and others; however, new mechanisms are being found at an alarming pace. In addition, investigations to date have routinely centered on single-cell mechanisms of drug resistance, and cancer is truly a three dimensional disease. The elucidation of mechanisms surrounding (1) how tumors interact with their normal microenvironment, (2) how tumors interact in a three-dimensional environment, and (3) a better understanding of basic tumor physiology and biology may supersede in importance those previously elucidated single-cell mechanisms of chemoresistance.

Since the infancy of radiology and radiation therapy, reactions to radiation have been noted and followed, and attempts have been made to minimize these reactions. We have turned to radiobiologists to explain these reactions and to radiation oncologists to prevent or decrease the normal tissue effects of radiation therapy. Radiation toxicities are divided into early (acute) and late (chronic) reactions; however, it is important to note that severe toxicities are rare and occur typically in less than 5% of veterinary radiation therapy patients.

Malignant tumors of the head and neck region occur commonly in veterinary medicine. Unfortunately, tumors in the head and neck can cause treatment dilemmas because many neoplastic entities at this site are locally aggressive. Additional local therapies such as radiation therapy are becoming commonplace as standardized therapies for many head and neck tumors in veterinary medicine.

A wide variety of cancer therapy resistance mechanisms are available, with perhaps surprising overlap between causes of chemotherapy and radiation resistance. As previously discussed, most of the widely used chemotherapeutic agents and gamma-radiation utilize apoptosis as the common death pathway, thereby making apoptosis and the ability to manipulate apoptosis of integral importance to the future of cancer therapy. This is evidenced by the information explosion on this topic in the last 5 years. Obviously much remains to be learned. However, with the aforementioned cooperation of the oncology team and a greater understanding of the molecular mechanisms behind cancer and cancer therapy resistance, response rates, survival times, the quality of life of patients enduring antineoplastic therapies, and the importance of comparative oncology can only increase. We look forward to the findings in the coming years on this incredibly clinically relevant topic with great fondness and uncertainty.