I was not planning on my next blog to be about oral malignant melanoma (or OMM) in dogs, but I just attended a really great meeting on the topic in New York City. It cut into my weekend family time, so I am happy that the meeting was so informative.
This meeting was VECOG, or Veterinary Eastern Cooperative Oncology Group. It’s a group of local oncologists from the Northeast who meet one to two times a year. Recently we changed the format and decided to dive into a specific tumor topic in depth. The meeting is attended by oncologists, residents, surgeons, pathologists, and a few radiation oncologists. Like my recent meeting in Paris, this is not a review of the basics but a chance to see what is current and discuss the challenges in diagnosing, grading, staging and treating these tumors.
Let’s touch on the highlights. I will do this in 2 parts, because there is was a lot of interesting info to share.
Topic 1: Melanoma Immunotherapy in people
Dr. Margaret Callahan spoke on the “Future of Melanoma Therapy at Memorial Sloan Kettering Cancer Center.” Dr. Callahan reviewed an immune therapy called ipilimumab (IPI) that when combined with dacarbazine chemotherapy improved overall survival in people. We also discussed the interesting toxicity associated with immune therapy. It’s different than the chemotherapy side effects (which is typically nausea and vomiting). With this immune therapy, they see skin rashes, diarrhea, liver and endocrine disorders, due to immune inflammation.
In the clinics, the response can take 3 to 4 months, with only about 15% of the patients responding. That may sound small, but those who responded also had long-term durable responses. Basically, this therapy is beneficial for some people, and not for others. One of the things that needs to be discovered: is there a biomarker that is common to those for whom this is effective? If there is, we can look for that biomarker in future candidates and more accurately predict who will benefit from the treatment.
Topic 2: Melanoma Immunotherapy in dogs
Dr. Rowan Milner from the University of Florida Melanoma reviewed the development of a research melanoma vaccine used at his facility. This vaccine has a different antigen or target (GD3, ganglioside-3) than the commercially available Merial melanoma vaccine. After Dr. Milner reviewed the survival times based on different sites (oral, foot, skin), he reported an unexpected result – new tumors were triggered.
The example Dr. Milner gave us was a dog with OMM (oral malignant melanoma). Two years after receiving the treatment, the dog was diagnosed with skin MCT (mast cell tumor). When the MCT was treated with an oral chemotherapy, the MCT responded, but then the oral tumor got larger. When dog was re-vaccinated, the oral melanoma got smaller — but sadly, the dog developed lung metastasis.
This effect is something we will need to closely monitor in patients with multiple tumors, especially when immunotherapy is involved. Dr. Callahan contributed at this point that people treated with other immune modulators are also monitored for skin squamous cell carcinomas.
Dr. Phil Bergman also updated us on the commercially available Merial melanoma vaccine, which is available through medical oncologists. This xenogeneic DNA melanoma vaccine is effective for digit melanomas, as well as oral MM. This study was published last year, and is reviewed in my chapter on melanoma in the Dog Cancer Survival Guide. So check out the guide and come back next week to read more about my great meeting and what’s new for oral melanoma.
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All my best,