Mason Immunotherapy Research

Our Research

About cancer immunotherapy

Cancer immunotherapy aims to create, redirect, or strengthen an immune response against cancer cells within the body. In essence, this enables the patient's immune system to help target their cancer cells.

Immunotherapy encompasses many different treatment modalities, including monoclonal antibodies, cancer vaccines, cell-based therapies (CAR-T cells, antigen presenting cell vaccines, others), and checkpoint inhibitors.

Merits of this treatment approach

Immunotherapy is often highly specific - instead of affecting all rapidly-dividing cells, its effects can be targeted to a selective population of cells (cancer cells) that have a specific, shared characteristic. This allows cancer treatment to be more precisely applied to cancer cells, while sparing as many normal cells as possible.

Also, subsets of immune cells have the capacity for memory - if they are trained to recognize and kill cancer cells, the immune system as a whole can retain this knowledge over the course of years. Constant immune surveillance in the body combined with long-term memory of what cancer cells "look" like enables early immune recognition and targeting of cancer relapse.

Types of Cancers Investigated

  • Canine Hemangiosarcoma

    Hemangiosarcoma is a common, aggressive cancer that arises from the cells that line blood vessels. Common sites of occurrence include the spleen, liver, and the right side of the heart. The current standard of care is surgical removal of the spleen followed by chemotherapy. Unfortunately despite surgery and chemotherapy, the disease usually spreads and most dogs succumb to their disease within 6-12 months of diagnosis. The Mason Lab have developed an antibody therapy to delay or prevent the spread of disease after surgery.

  • Canine Lymphoma

    Non-Hodgkin’s lymphoma (NHL) is the most common cancer of the blood in dogs. It is a cancer of white blood cells known as lymphocytes and it occurs in lymphoid tissues such as the peripheral lymph nodes, spleen and bone marrow.

    The disease frequently occurs in middle aged and older dogs (median age 6-9 years). Certain breeds are predisposed to lymphoma and include Boxers, Bull Mastiffs, Basset Hounds, Saint Bernards, Scottish Terriers, Airedales, and Bulldogs. 

    Most dogs with lymphoma develop enlarged lymph nodes, often felt as firm swellings underneath the jaw (submandibular lymphadenopathy), in front of the shoulder blades (prescapular lymphadenopathy) and/or behind the knees (popliteal lymphadenopathy). The most common subtype of NHL in dogs is Diffuse Large B-Cell Lymphoma.

    Combinations of systemic chemotherapy drugs that inhibit cell division and kill rapidly dividing cells lead to clinical remission in approximately 75 percent of dogs. However, the majority of canine patients relapse with lethal, drug-resistant lymphoma within 6 to 9 months of diagnosis and treatment.

    This statistic demonstrates that current therapies to treat canine B-NHL are insufficient to eliminate all the cancer cells and provide a “cure” for this disease.

    Dr. Mason’s laboratory has worked on two different immune therapy approaches to treat lymphoma.

    1. Preventing disease relapse in dogs that have been successfully treated with chemotherapy.
    2. Immune therapy approach for dogs that have relapsed with lymphoma and are developing chemotherapy drug resistant disease.
  • Canine Osteosarcoma

    Osteosarcoma is the most common primary bone tumor found in dogs, and in most cases, it occurs in middle aged to older large and giant breed dogs. The exact cause of osteosarcoma is not known although it is likely that many factors are involved. Increasing evidence suggests that both canine and pediatric osteosarcoma might respond well to immune therapy when used in combination with other treatment modalities.

    It is an aggressive cancer that causes pain in the affected bone and lameness, and weakens the bone structure making it likely to fracture spontaneously. The tumor frequently spreads to the lungs and also to other bones.

    • Standard treatment consists of amputation of the affected leg, followed by chemotherapy to prevent or delay the spread of the tumor (metastasis).
    • Even with this treatment, the majority of dogs still develop metastasis and die from OSA within one year of diagnosis.
    • When amputation is not an option (for either medical or personal reasons), treatment is directed at decreasing the pain caused by OSA.
    • Palliative radiation in combination with pain medications provides pain relief in up to 85 percent of dogs. However, these treatments do not usually prevent disease progression and most dogs will succumb to intractable pain or pathological bone fracture within three to five months of diagnosis.

    Immune Therapy for the Treatment of Osteosarcoma

    The immune system plays an important role in identifying and killing cancer cells in the body. The Mason lab has evaluated a vaccine called ADXS31-164, to stimulate the body’s immune system to recognize and  kill bone cancer cells.

    The vaccine is made from the bacteria Listeria monocytogenes, which has been genetically modified to express a tumor protein (HER-2/neu) that is found in many cancer cells, including canine osteosarcoma.

    • The bacteria is highly attenuated, which means it has been weakened so as not to cause disease when administered to the patient.
    • The vaccine is given by intravenous injection and aims to stimulate an immune response against cells that express the tumor protein (HER2/neu).
    • In this way, the immune system can be trained to recognize both primary and metastatic cancer cells and eliminate them, helping to delay the onset of metastatic disease and in cases where dogs are treated without amputation, prevent primary tumor progression.
  • Canine Transitional cell carcinoma

    Transitional cell carcinoma (TCC) is the most common type of bladder cancer in dogs. Most dogs with TCC initially show signs such as straining to urinate, increased frequency of urination, or blood in the urine. As the tumor grows, it obstructs the flow of urine, which can become life-threatening. TCC can also spread to nearby lymph nodes, lungs, and bones. In most cases, TCC of the bladder cannot be cured.