Genetic Testing - Follow up

This week, I met with one organization that specializes in canine DNA testing, and two universities that are actively researching different treatment methods for hemangiosarcoma, to learn more about how genetic testing could:

  • help determine if some dogs are genetically predisposed to hemangiosarcoma,
  • be used as a method for early detection of this disease,
  • enable more targeted treatment plans

I have broken this article into 3 sections based on the bullet points above. The goal here was to explore a topic that may be of interest to people whose dogs have hemangiosarcoma, and try to present the information in a way that is useful for pet owners. I am not a doctor, veterinarian, or researcher. I am a pet owner who lost his best friend, Bear, to hemangiosarcoma, and I am simply trying to help someone else who is forced to confront this terrible disease in the future.


Predisposition

Picture this: you bring your new puppy to the vet for a checkup. Your vet notices that your puppy is a high risk breed, and recommends a DNA test to determine whether or not your dog contains any known genetic markers that are associated with hemangiosarcoma. A week later, the results of the DNA test come back, and your puppy is found to have a few genetic mutations that are associated with this disease. This does not mean your dog will develop cancer later in life, it just means their risk for developing this disease may be higher. Your vet says not to worry, but when your puppy reaches age 5, the usual physical check ups should be supplemented with more sensitive cancer-screening procedures. This allows you, as a pet owner, to be proactive in screening against a type of cancer that usually goes undetected until it's too late. More aggressive screening could lead to earlier detection, which in turn, could lead to better treatment outcomes. (end hypothetical).

Current reality: according to all three of the organizations we met with, the road to making the above scenario a reality is a long one. That's not to say it shouldn't be pursued though, but there are a lot of things to consider. For example, hemangiosarcoma is very likely to be the result of multiple causes (e.g. a cumulation of genetic changes + environmental factors), so a simple DNA test to determine an individual's predisposition may not be possible. However, the fact is, scientists simply haven't looked yet, so it's not something that we can rule out. 

Another challenge that one of the researchers mentioned is that "markers are not actionable". In other words, if a dog is determined to be predisposed to developing hemangiosarcoma later in life (given the results of a DNA test), there isn't much a pet owner can currently do to address it. For example, in the above scenario, we mentioned more sensitive cancer-screening procedures being employed after your dog reaches a certain age. However, there actually aren't a lot of screening procedures that would help at this point. Based on information we received from both veterinarians and researchers, echocardiograms, ultrasounds, and other methods may not be sensitive enough to detect hemangiosarcoma at an early stage (the Early Detection section below discusses some promising research in this area, though). The question then becomes, is it useful or ethical to let a pet-owner know that their dog may be more likely to develop an incurable, aggressive cancer, when there isn't anything they can do about it?

Future Research: The canine DNA testing company we spoke with expressed an interest in subsidizing research (in their own labs) to help identify genetic markers associated with hemangiosarcoma. Whether or not this is something we can participate in will be discussed in a follow up call later this month. We want to do everything we can to support the right research, but given the costs of a long term study and the challenges mentioned above, we may need to raise more money first, or pursue a different kind of strategy for fighting hemangiosarcoma.


Targeted Treatment

Picture this: your dog is diagnosed with hemangiosarcoma. However, what used to be standard therapy (surgery + chemo), has recently been replaced by a more personalized treatment plan. The first step is still the same - the primary tumor is removed via surgery. However, instead of resorting to chemotherapy, which floods your dog's system with drugs that indiscriminately kill both healthy cells and cancer cells, your dog is given something called a gene inhibitor, which prevents the expression of certain genes involved in tumor generation. Your dog's life is extended without the decrease in quality of life that is often associated with chemotherapy. (end hypothetical).

Current reality: The recently published (November, 2017) work at the University of Pennsylvania, which you can read about here, has already put us on the path to this type of personalized medicine. Two of the researchers we spoke with explained that not every tumor is the same, and that cancer is often driven by different mutations. However, using a DNA test to detect which mutations are involved for a given case would allow doctors to find the so-called Achilles' heel for an individual tumor, and then use certain gene inhibitors to prevent the expression of the genes involved. If fighting cancer is like war, chemotherapy is like the machine gun that kills wildly and indiscriminately. The new regime (surgery + gene regulation), however, is more like a sniper (in the sense that it doesn't aim to kill everything in it's path, but to take calculated shots, instead).

Future Research: Out of the three organizations I spoke with, continuing research that explores personalized medicine (via gene therapy) as a method to fight hemangiosarcoma was the priority of only one. After talking to this university briefly about their goals and their current work, the direction felt very progressive to me. As we continue to develop our own direction, we will definitely be having more conversations with this university to see how we can support their work.


Early detection

Picture this: you bring your dog to the family vet for a routine checkup. In addition to the usual routine of weighing your pup, checking teeth and gum health, etc, your vet draws some blood and sends it off to a lab. A few days later, the results come back, and a small number of tumor cells were detected in your dogs blood. Your dog has shown no signs of cancer or any other health issues, but the extremely sensitive blood test has picked up on microscopic disease. Not only that, but technicians were able to extract DNA from the circulating tumor cells. Now, instead of allowing the tumor to grow for a few more months or years in silence, you can start addressing the issue now. (end hypothetical).

Current reality: Research is currently underway to develop methods for detecting a small number of tumor cells in the blood. One notable study is the Shine On Project at the University of Minnesota. This study is employing a blood test to see if hemangiosarcoma can be detected early by looking for certain cells in the blood stream. If these kinds of tests are also sensitive enough to detect the DNA that belongs to the tumor, then the types of targeted treatments we mentioned above could potentially be employed in the earliest stages of the disease. However, one of the researchers we spoke with warned that it could be several years before this type of screening in available for pet-owners and their dogs.

Future Research: Unfortunately, we didn't get a chance to talk much about this type of research during this week's conversations. However, we will be exploring this topic again as we continue researching material for our awareness campaigns.


Thanks

I hope the information above helps someone, somewhere. Thank you for reading.