If your dog has been diagnosed with lymphoma, and you have chosen to pursue chemotherapy, then your vet may or may not have started out your dog’s treatment protocol with a drug called L-Asparaginase, or Elspar. Originally the first drug given during the WI-Madison chemotherapy protocol (the most common protocol used for lymphoma), Elspar is now being removed from the initial round of chemo. This has caused some concern among pet owners because this drug is known for rapidly attacking the cancer, often leading to dramatic results and a quick remission.
Why does this drug work so well and so fast? First we have to understand the role that the amino acid asparagine plays in the body. Asparagine is something that all cells need in order to produce protein. However, cancer cells, especially lymphatic cancer cells, need huge amounts of this amino acid to survive and reproduce. A typical healthy cell does not need much asparagine and can produce what it needs internally. A cancer cell needs to rely on outside sources to feed itself. That’s where L-Asparaginase comes in.
L-Asparaginase takes advantage of this situation by destroying any asparagine ouside of the cells, thereby cutting off the food source for the cancer cells. Within a short period of time, the cancer cells die off when they can no longer get enough asparagine to fuel themselves…resulting in those dramatic results and quick remissions. To the average pet guardian, Elspar often seems like a miracle drug that buys enough time for the other chemotherapy drugs to get to work.
So if Elspar works so well, why is it being removed from the original WI-Madison protocol? According to Dr. David Vail at the UW-Madison School of Veterinary Medicine, several research studies have shown that using this drug at the begining of the protocol does not add to the length of the initial remission. As a result, more and more vets are choosing to save Elspar as part of a rescue protocol, when the cancer cells start to become resistant to the original chemo drugs.
So, if your vet suggests holding off on this valuable chemotherapy agent, it may actually be a good thing for your pup down the road. If your vet does choose to administer this chemo drug early on though, they’re not necessarily wrong either. Find out what their rationale is — being an active part of your dog’s treatment is essential throughout the process. Don’t be shy about asking questions and expecting honest, clear answers. Your first responsibility is to your dog and he or she is relying on you to be their voice and advocate during cancer treatment. And, even the best vet can sometimes learn something new…even from one of their clients!
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Jeffreys AB, Knapp DW, Carlton WW, Thomas RM, Bonney PL, deGortari A, Lucroy MD. Influence of asparaginase on a combination chemotherapy protocol for canine multicentric lymphoma. J Am Animal Hosp Assoc. 41:221-226, 2005.
Piek CJ, Rutteman GR, Teske E. Evaluation of the results of a L-asparaginase-based continuous chemotherapy protocol in dogs with malignant lymphoma. Vet Quarterly 21:44-49, 1999.
Valerius KD, Ogilvie GK, Mallinckrodt CH, Getzy DM: Doxorubicin alone or in combination with asparaginase, followed by cyclophosphamide, vincristine, and prednisone for treatment of multicentirc lymphoma in dogs: 121 cases (1987-1995). J Am Vet Med Assoc 210:512-516, 1997.
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