No Studies Support a Cure for Feline Leukemia Virus

Q: My cat was recently diagnosed with feline leukemia virus (FeLV), and I was devastated to hear this news. He is currently doing well, but I am, of course, very concerned. A friend of mine recently told me about a new treatment called lymphocyte immunomodulator (LCTI) that she says can cure FeLV. Can you tell me about this drug and whether it is an effective treatment?

Elizabeth the cat

A: Thank you for contacting us, and I am very sorry to hear about you kitty’s diagnosis. FeLV is a very common viral infection in cats, and while it is true that it often shortens the lifespan of infected cats (the average lifespan after diagnosis is approximately two-and-a-half years), it is important to note that infected cats can have a high quality of life for prolonged periods of time if they are managed appropriately.

Given the ubiquitous nature of this virus and the significant effects it has on feline health, there has been a lot of research focused on identifying an effective treatment option for infected cats. LCTI has been promoted as a potential therapy for FeLV in cats, and perhaps a brief description of the rationale for the investigation of this drug may be helpful as a first step in answering your question.

A vital component of the immune system is the activity of a variety of white blood cells (WBC), which respond to invasion of the body by foreign organisms and viruses by directly attacking these invaders and/or by producing proteins (such as antibodies) that ultimately result in their neutralization and removal.

One type of white blood cell called a T cell (because it matures in an organ called the thymus) has receptors on its surface that recognize foreign (non-self) organisms and either directly attack the offender or assist in mounting a response by producing chemicals that attract other WBCs or by presenting the offending organism to other components of the immune system for identification as a foreign entity to be destroyed.

Compounds produced by WBCs to communicate with and/or activate other WBCs are called cytokines. LCTI is a cytokine in the class of what are termed “immune modulators” that some manufacturers have claimed activates a type of white blood cell called a CD8 cytotoxic (cell killing) T cell, inducing it to attack and destroy FeLV-infected cells. There have also been claims that LCTI leads to clinical improvement in FeLV-infected cats. These claims have not, to my knowledge, been substantiated by rigorous scientific, peer-reviewed studies. For these reasons, we do not consider LCTI to be an efficacious means of treating cats with FeLV infection.

While there is currently no proven cure for FeLV infection in cats, it is important to reiterate that cats with FeLV infection can often be managed for long periods of time by taking preventive measures such as appropriate prophylaxis against intestinal parasites and biannual visits to the veterinarian and by addressing problems such as secondary bacterial infections and anemia that may arise aggressively.

Of course, it is important to protect the health of other cats by taking appropriate measures such as isolation of FeLV cats (or cats of unknown FeLV status) from non-vaccinated FeLV negative cats, by vaccinating cats at risk for FeLV infection, and by keeping cats indoors so that they do not infect other outdoor cats. Please speak with your veterinarian about the means by which you can prolong the lives of cats infected with FeLV while protecting other cats from being infected.

I hope that this is helpful, and that this note finds you and your kitty well. Best regards, and please keep in touch.