Might There Be Some Potential New Ways To Treat Feline Lymphoma?

Ron Hines DVM PhD

I am optimistic about the future.

That is because although its not nearly as common as it is in cats, lymphoma affect people as well (the disease is not transferred from cats to humans, so don’t worry about that) and it is primarily human medical research that spurs innovation.

Until recently, human lymphomas were treated with chemo cocktails almost identical to the ones used in cats. (eg doxorubicin, cyclophosphamide, vincristine, chlorambucil, corticosteroids). But over the last few years, newly discovered knowledge on how these out-of-control lymphocytes rely on messenger chemicals to proliferate have opened treatment options for humans that never before existed.

These are the “nibs” Janus kinase inhibitors (JAK inhibitors). The same class of compounds as Zoetis’ Apoquel®  (oclacitinib) that is so effective in blocking itching signals in dogs and Pfizer’s Xeljans® (tofacitinib), used to treat rheumatoid arthritis in people.   

In 2013, the FDA approved another “nib”, Ibrutinib (Imbruvica®) for a type of human lymphoma.  (ref) Results to date in humans are quite promising. (ref1, ref2)

Another natural messenger compound was discovered that is involved in the movement and maturing of lymphocytes – the cells that make up a lymphoma. It is S1PR1 .  Once that was discovered, pharmaceutical researcher developed S1PR1 blockers (aka modulators,antagonists,agonists) to block the S1PR1 message. (ref) . Some produced custom antibodies  (mAbs ) to destroy it. Those studies are still in progress and I do not believe any have reached the market other than Gilenya, used to treat MS.  Another, Biogen’s MT-1303 is still in clinical trials for chronic intestinal inflammation in humans (Crohn’s). Similar chronic intestinal inflammation usually precedes lymphoma in cats.

I am neither a pharmacologist nor an oncologist, but to me, that is the direction things appear to be going. There are drawbacks to the use of these drugs in our pets: their current high price, perhaps that cat’s might become immune to them in their “humanized” forms. Some messengers are the same across species lines, some are slightly different. I do not know of anyone who has yet attempted to give these or similar medications to cats. But high price did not stop Zoetis from developing Apoquel® , a similar high-tech bioengineered “nib” that takes advantage of our new knowledge of the immune processes underlying many of the diseases our pets suffer from.

My interest in these meds sprang from an email I received from a cat-owner in Hamburg, Gr. His cat had been diagnosed with lymphoma and the medications were no longer working. I attempted to contacted the most knowledgeable person on these newer treatment options, Dr. Asher Chanan-Khan for his advice. But I was was unsuccessful in doing so. If you are more successful, let me know.

When humans develop lymphoma, the tumor can be genetically typed (DNA profiled) to tailor the treatment plan to medications that are most likely to be successful. (ref) That was recently done in dogs as well. (ref) Perhaps we have or soon will have that option for cats as well.

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