「Safe to use for borderline tumors.」
J：From your perspective as a clinician, is there still a big difference between having such content as a treatment method and not having it?
Ushigusa：I think this depends on the individual. For me personally, at least, as a person who actually provides treatment, I want to explain the background of the treatment I provide to the owner without delay. In fact, I would like to 。。。。 I don’t really want to say “mogo mogo mogo”. Of course regenerative medicine is still mogo-mogo-mogo (laughs), but that is the part about effectiveness, and the theory is very solid. It is also becoming safer. So that’s the part I can explain exactly.
With that in mind, we thought that immuno-cell therapy would be another option to add to the existing treatments. Regenerative medicine is still uncertain. But the theory that even a small part of the treatment may be effective is firmly established. I think it will be very significant to be able to use such things for my own treatment eventually.
Another is that immuno-cell therapy is a safe treatment that can be used for borderline benign and malignant tumors that are difficult to diagnose. The fact that it can be used in a delicate line is one of its major advantages.
J：Could you be more specific about the treatment for borderline tumors?
Ushigusa：This is because, for example, a dog or cat diagnosed with cancer is given an anticancer drug, which is later found to be a misdiagnosis through necropsy or other means. In other words, what if the cancer was not malignant or was not formed in the first place? Nowadays, the sensitivity of diagnosis has increased, and many tumors with ambiguous boundaries have emerged. The idea of administering highly toxic anticancer drugs to such cases is very frightening for patients and, of course, for us as therapists. But under the current circumstances, this is a real risk.
I believe that many such cases will occur as the sensitivity of diagnosis increases, in other words, as we try to detect the very early stages of the disease. In fact, we have had a case where a cat was diagnosed with a malignant tumor of the intestinal tract, treated with immuno-cell therapy, and survived for more than three years without symptoms, only to find no tumor on necropsy when the cat died of renal failure. We do not know if it was a diagnostic problem or if the treatment was successful. In any case, that doesn’t mean that immuno-cell therapy is a good reason, but I would say that immuno-cell therapy is a mild, one-step-away alternative therapy when applied under such circumstances. I think it is very meaningful to provide another treatment option for owners in such cases where the treating parties are not sure whether the three major therapies should be applied.
「Activated lymphocyte therapy is the foundation of immune cell therapy」
J：Could you tell us about your own feelings about immuno-cell therapy?
Ushigusa：I have a very good feel for activated lymphocyte therapy as an adjunctive immuno-cell therapy after surgery. The difficulty is that the actual visible tumor has already been surgically removed, so it is difficult to easily accumulate data. But in clinical practice, when you don’t want to use anticancer drugs, but you want to do the best you can to prevent postoperative recurrence, I think it is the best item among the existing treatments. If you think better of it, if blood is drawn before surgery and culture is started, it can be administered relatively early in the postoperative period and can be expected to boost the immune system, which is weakened by the surgery itself. It can also be expected to have the effect of striking tumor cells at the time when they are most active in the remaining microscopic areas. The fact that treatment with immune cells is a treatment that can have a systemic effect, not just a local one, also fits our purpose, doesn’t it? However, I also think that it is difficult to just raise the immunity of the whole body. After all, we believe that the combination of dendritic cell therapy, which specifically strikes cancers, will become the mainstream for solid tumors these days.
J：Some of the doctors reading this interview may be considering the use of immuno-cell therapy in the future, while others may be skeptical about the actual results of immuno-cell therapy. Dr. Ushikusa, you have treated a certain number of patients with activated lymphocyte therapy, mainly in cancer treatment, and would like to tell us what you think about it from a bird’s eye view?
Ushigusa：Yes, I agree. To be honest, at this stage, immuno-cell therapy, including activated lymphocyte therapy, is still in its developmental stages, and I don’t believe it is a magical, perfect treatment that will make a large tumor mass disappear. I don’t think it is a magic, perfect treatment that will make a large tumor mass disappear! I don’t feel that it is a perfect treatment that will magically disappear a large tumor mass. At this stage, I think it is only an adjunctive treatment. However, I believe that if we combine dendritic cell therapy, DNA vaccines, and other therapies with this as a basis, the possibilities and future potential will be unlimited.
The problem with activated lymphocyte therapy is that no matter how much we increase the number of T lymphocytes, the soldiers that beat cancer, the number of tumor cells that are the enemy has often already increased to the point that we cannot keep up. On top of that, to make matters worse, some of the antigens are also hidden on the surface of the tumor cells, and I wonder if it is really possible to deal with all tumors. We believe that administering only T lymphocytes to such tumors will have little effect. In this context, I am interested in dendritic cell therapy, in which a gene encoding a cancer antigen is loaded onto a vector (DNA carrier), which is then injected into dendritic cells to present the antigen artificially on the surface of dendritic cells. This type of cancer therapy, if successful, will be the first of its kind in the world. If such a cancer treatment works, it will be the best treatment in my opinion. In fact, a DNA vaccine for malignant melanoma is already on the market in the United States. I think we can find a newer treatment method by combining such things.
In human medicine, it is precisely because of the activated lymphocyte therapy that various immune cell-based therapies have been developed. In veterinary medicine as well, it is essential for veterinarians to first understand the background of the molecular mechanism and then accumulate clinical data on activated lymphocyte therapy, and I believe that we cannot proceed to the next step unless this is done in a logical and well-defined manner. Activated lymphocyte therapy is the foundation of immuno-cell therapy, and if we go beyond that to other therapies, immuno-cell therapy in the veterinary field will go in a wrong direction.