There are already a number of treatments for cancer, but some don't work in particular type of cancer. For instance, CAR-T therapy has only been approved for blood cancers or leukemia and not solid tumors, but that might likely change soon.
Cancer Kill Switch Found
In a new study, scientists at the University of California, Davis (UCD) and Indiana University have figured out a way to blow open the "doors" that lead to the core of cancerous tumors to allow for medication administration. The method functions by setting off a "timer bomb" on the blood vessel-associated tumor's lining cells.
Until these vessels are opened, modified immune cells will not be able to readily invade the cancer in order to combat it. These vessels regulate access to the tumor tissue. The "death" receptor on these cells is actually a timer bomb, known as Fas (or CD95).
Fas has, according to the researchers, been "undervalued in cancer immunotherapy" up until recently. Not a single Fas antibody has progressed to clinical testing thus far.
"Previous efforts to target this receptor have been unsuccessful. But now that we've identified this epitope, there could be a therapeutic path forward to target Fas in tumors," explains immunologist and senior author of the study Jogender Tushir-Singh.
The antibody functions as the cell's kill switch when it attaches to this epitope, which is a particular region of the death receptor. Other cancer treatments, such as CAR-T therapy, can reach more of their targets-many of which are clustered and concealed within the tumor-once this immune checkpoint is breached.
What Is CAR-T Cell Therapy?
CAR T-cell therapies are not as frequently employed as immune checkpoint inhibitors, but they have demonstrated a similar capacity to destroy lymphomas and leukemias that are extremely advanced as well as to prevent cancer for a long time.
The Food and Drug Administration (FDA) has approved six CAR T-cell treatments since 2017. The therapy received a green light for the treatment of blood malignancies, including multiple myeloma and some types of leukemia and lymphomas.
CAR-T therapy works by teaching a person's own T-cells, or white blood cells, to attach to and destroy particular kinds of malignant cells. Unfortunately, because "bystander" cells lack the identifiable antigens that tumor cells are typically targeted with, these immune cells are typically unable to pass through them.
CAR-T therapy has therefore only been authorized to treat leukemia or blood malignancies. It doesn't consistently work well against solid tumors.
"These are often called cold tumors because immune cells simply cannot penetrate the microenvironments to provide a therapeutic effect," Tushir-Singh explained. "It doesn't matter how well we engineer the immune receptor activating antibodies and T cells if they cannot get close to the tumor cells. Hence, we need to create spaces so T cells can infiltrate."
Researchers believe more research should be done on the two crucial regions of the Fas receptor that the Fas ligand they produced was able to engage. Future medications may target these areas.
Future engineering of CAR-T cells to target these receptor regions on bystander cells could greatly increase the therapeutic's efficacy against cancers. The expert noted that the study "sets the stage to develop antibodies that activate Fas, selectively kill tumor cells, and potentially support CAR-T-cell therapy in solid tumors."
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