If the standard-of-care CHOP lymphoma chemotherapy protocol isn’t an option for your dog or fails to control her illness, there are other options. Tanovea chemotherapy (generic name: rabacfosadine) is the first FDA-approved treatment for lymphoma in dogs.
Key Takeaways
- Tanovea is effective for lymphoma, but not as effective as the gold standard protocol, CHOP. It can be used as a rescue protocol for CHOP, or as a standalone treatment, or in combination with other chemotherapy drugs. It is showing limited promise in a few other cancer types, as well.
- Tanovea is an injectable chemotherapy drug, which means it is given in the hospital in a very careful manner, never at home. When used alone it’s given once every three weeks for a total of five treatments. It is sometimes alternated with other agents, as well.
- Tanovea starts working as soon as it encounters a lymphoma cell in your dog’s body. Inactive until it reaches a lymphoma cell, once there it converts into its active form and triggers apoptosis (natural cell suicide) in the lymphoma cell.
- Side effects of Tanovea include gastrointestinal side effects like vomiting and diarrhea, decreased white blood cell count, thinning hair coat, reddened skin, skin and ear infections, and rarely, pulmonary fibrosis (most commonly in breeds predisposed to it, like West Highland Terriers).
- When given alone to dogs with lymphoma, Tanovea has a 73% response rate with a remission lasting 4-6 months.
What is Tanovea Chemotherapy and What Does It Do?
Rabacfosadine is known by the brand name Tanovea.®,2 Tanovea chemotherapy is an injectable cytotoxic agent given in the veterinary hospital over the course of several weeks (see below).
Tanovea is a prodrug3, which means that it is inactive in its initial form. Specific canine cancer cells, particularly lymphoma, contain enzymes that convert rabacfosadine into the active agent.3,5,8 This allows Tanovea to specifically target the cancer cells, while leaving normal cells unharmed.
Like many chemo drugs, Tanovea chemotherapy is given by injection into the dog’s vein. The infusion takes about 30 minutes3 and is done at the vet hospital.
Brand Names
Tanovea-CA1 is the very first FDA-approved treatment for lymphoma in dogs.7
How Tanovea Affects Cancer
After being injected into a vein, rabacfosadine travels through the body. Rabacfosadine itself is inactive, and does not damage cells that it encounters.
Except when it encounters lymphoma cells. Inside lymphoma cells, it goes through a couple of conversions before reaching its final form, PMEG diphosphate. PMEG diphosphate is cytotoxic, and inhibits DNA synthesis and triggers apoptosis (programmed cell death).5
How do we know it doesn’t harm normal cells? Most cells do not have the two enzymes needed to convert Tanovea from its initial form to the cytotoxic drug that kills the cancer cells. Lymphocytes are the primary cell type that has these enzymes.
Tanovea Chemotherapy Success Rates
Tanovea chemotherapy is only used for cancer treatment in dogs, and so far it only shows promise for a couple of cancer types (see below).
In vitro studies looking at other cancers have not shown a response.
Lymphoma
Rabacfosadine is fully FDA-approved to treat canine lymphoma as of July 2021.7
How long does Tanovea last? Given alone, it has a 73% response rate with remission generally lasting 4-6 months.8 That means that 73% of dogs taking Tanovea went into remission, and that remission generally last 4-6 months.
Tanovea can be used as a first-line treatment for lymphoma, or it can be used a second-line treatment or rescue therapy.10
As of early 2022, studies are underway to evaluate how Tanovea does when combined with other chemotherapy drugs or protocols.
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- An initial study that alternated Tanovea with doxorubicin (treatments once every three weeks for a total of six, with three of each drug) yielded response rates and remission duration about the same as a full CHOP protocol.5 A confirmatory study is underway.
- Colorado State University, University of Wisconsin-Madison, and University of California-Davis are testing a protocol that uses rabacfosadine as part of CHOP.
We will update this article with results as they are released.
Multiple Myeloma
Early studies in dogs with multiple myeloma show promising results.9 A confirmatory study was completed in 2021 but has not been published yet. We will update this article with results as they are released.
Lymphoid Leukemia
Early studies using Tanovea chemotherapy in dogs with lymphoid leukemia have shown promising results, but more study is needed.
This episode of DOG CANCER ANSWERS has a lot of information about Tanovea from one of the veterinarians involved in its use right from the beginning of its interesting history.
Dr. Douglas Thamm has been involved with Tanovea since the beginning. He shares his insights into when (and when not) to use Tanovea in this episode of DOG CANCER ANSWERS.
Tanovea Side Effects
Rabacfosadine can cause similar side effects to many other chemo agents but does have potential to cause some unique ones.
The majority of side effects are mild9, and either resolve on their own or with symptomatic treatment at home.
Side effects of Tanovea include:7.8
- Gastrointestinal signs such as vomiting and diarrhea
- Decreased white blood cell count
- Thinning hair coat
- Reddened skin
- Skin and ear infections
- Pulmonary fibrosis
Dogs undergoing treatment with Tanovea should be monitored closely for changes in the skin and ears to catch any potential infections as early as possible. Depending on how bad the side effects are, the next dose of Tanovea can be delayed to give the skin extra time to heal.7
Pulmonary fibrosis is the most concerning potential side effect observed so far with rabacfosadine, but thankfully it is rare.7
- Changes in the lungs are delayed and may not be apparent for several months after treatment.
- Pulmonary fibrosis has been fatal in about 2% of dogs treated with Tanovea at this point. Researchers are reviewing the literature to try to identify risk factors, but so far this side effect appears to be idiosyncratic (due to individual differences that aren’t common to most dogs).
- It is generally recommended to avoid Tanovea for dogs who already have lung problems or who are of a breed or mix that has a genetic predisposition to developing pulmonary fibrosis (most notably West Highland White Terriers).7
When to Not Use Tanovea
There are some situations in which Tanovea chemotherapy should either not be used at all or used with caution.
Risk factors include:2
- West Highland White Terriers have a potential genetic predisposition to developing pulmonary fibrosis (which can be fatal) and should not use Tanovea
- Terrier breeds and mixes also have a potential genetic predisposition to developing pulmonary fibrosis and should not use Tanovea
- Dogs who have already been diagnosed with pulmonary fibrosis
- Dogs who have undergone half-body radiation in the past, as these dogs are already at risk of developing pulmonary fibrosis
- Dogs who are pregnant, lactating, or being used for breeding, due to risk of birth defects
Known drug interactions include:
- None known at this time
- Rabacfosadine is safe for dogs with the MDR1 mutation1
Known supplement interactions include:
- None known at this time
How Is Tanovea Administered?
Tanovea is an injectable cytotoxic agent, so it is given at veterinary facilities. It is given once every three weeks for a total of five treatments.9
When used with doxorubicin, the two drugs are alternated, with a treatment being given once every three weeks for a total of six treatments.6
Dose frequency may vary if Tanovea is used as part of another chemo protocol.
If the patient experiences side effects, treatment can be and usually is postponed to give the dog extra time to recover.7
What If I Miss a Tanovea Chemotherapy Dose?
If your dog misses a dose of rabacfosadine, contact your veterinarian or oncologist to determine the best time to reschedule. Doses postponed due to scheduling or travel difficulties can be given as soon as possible, while doses postponed due to side effects can be scheduled according to the dog’s needs.
Storage and Handling of Tanovea
Tanovea is a cytotoxic chemotherapy agent, so personal protective equipment must be used when handling and administering it. It is always given in the hospital setting by veterinary professionals.
- Packer R. What’s new in veterinary cancer? DVM 360. https://www.dvm360.com/view/what-s-new-in-veterinary-cancer-. Published December 28, 2020. Accessed December 11, 2022.
- Tanovea® (rabacfosadine for injection). Elanco US. https://www.elanco.us/products-services/dogs/tanovea. Accessed December 14, 2022.
- Saba CF, Vickery KR, Clifford CA, et al. Rabacfosadine for relapsed canine B-cell lymphoma: Efficacy and adverse event profiles of 2 different doses. Veterinary and Comparative Oncology. 2017;16(1). doi:10.1111/vco.12337
- Saba CF, Clifford C, Burgess K, et al. Rabacfosadine for naïve canine intermediate to large cell lymphoma: Efficacy and adverse event profile across three prospective clinical trials. Veterinary and Comparative Oncology. 2020;18(4):763-769. doi:10.1111/vco.12605
- Thamm DH, Vail DM, Post GS, et al. Alternating rabacfosadine/doxorubicin: Efficacy and tolerability in naïve canine multicentric lymphoma. Journal of Veterinary Internal Medicine. 2017;31(3):872-878. doi:10.1111/jvim.14700
- Weishaar KM, Wright ZM, Rosenberg MP, et al. Multicenter, randomized, double‐blinded, placebo‐controlled study of Rabacfosadine in dogs with lymphoma. Journal of Veterinary Internal Medicine. 2021;36(1):215-226. doi:10.1111/jvim.16341
- FDA grants first full approval for treatment of lymphoma in dogs. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-grants-first-full-approval-treatment-lymphoma-dogs. Published July 15, 2021. Accessed December 14, 2022.
- Tanovea. https://campaign.elanco.com/en-us/tanovea/. Published 2021. Accessed December 14, 2022.
- Thamm DH, Vail DM, Kurzman ID, et al. GS-9219/VDC-1101 – a prodrug of the acyclic nucleotide PMEG has antitumor activity inspontaneous canine multiple myeloma. BMC Veterinary Research. 2014;10(1):30. doi:10.1186/1746-6148-10-30
- Vail DM, Thamm DH, Liptak JM. Hematopoietic tumors. Withrow and MacEwen’s Small Animal Clinical Oncology. November 2019:688-772. doi:10.1016/b978-0-323-59496-7.00033-5
Tanovea is a trademark of Elanco or its affiliates.
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