For years, immunotherapies have played a crucial role in fighting cancer by teaching the body’s immune system to recognize and destroy abnormal cells. These therapies have shown remarkable success in treating a variety of cancers, including melanoma, lung, bladder, and kidney cancers. In the realm of prostate cancer, however, options have been more limited, with just one type of cancer vaccine currently approved for use. That could soon change, thanks to the emergence of a groundbreaking approach: CAR-T cell therapy.
A team of researchers at City of Hope Hospital in Duarte, California, is making strides with CAR-T cell therapy as a potential treatment for prostate cancer. CAR-T, which stands for chimeric antigen receptor T-cell therapy, involves modifying a patient’s own immune cells specifically T cells to better target and destroy cancerous cells. These T cells are equipped with engineered receptors that enable them to recognize specific markers, or antigens, on the surface of cancer cells. Once infused back into the patient’s body, these engineered cells go to work, actively hunting down and eliminating tumors that express the target antigen.
Currently, CAR-T therapy has shown success in treating blood cancers like leukemia and lymphoma, but its use in solid tumors such as prostate cancer remains experimental. However, early results from a new study suggest that CAR-T therapy could offer exciting new hope for those with advanced prostate cancer, particularly for patients whose disease has spread to the bones and is no longer responding to traditional hormonal treatments.
The researchers focused on a specific protein known as prostate stem cell antigen (PSCA), which is highly expressed in prostate cancer cells, especially in later stages of the disease. By engineering CAR-T cells to target PSCA, they aimed to create a treatment that could home in on prostate tumors with precision.
The clinical trial, which involved 14 patients with metastatic prostate cancer, administered 100 million CAR-T cells to each participant. Some patients also received a secondary treatment known as lymphodepletion, which helps ensure that the patient’s own immune cells don’t interfere with the action of the CAR-T cells. For some patients, the results were striking.
After just 28 days of monitoring, four patients showed a significant decrease in prostate-specific antigen (PSA) levels, an indicator of tumor shrinkage. One patient experienced an impressive drop of over 90% in PSA levels, along with substantial reduction in tumors in both bone and soft tissue. This patient’s positive response lasted for eight months. While five patients did experience mild side effects like cytokine release syndrome (a common immune response to CAR-T treatment), the symptoms were manageable and resolved with treatment.
However, not all aspects of the trial were without challenge. The CAR-T cells did not remain at high levels in the body beyond the initial monitoring period, which raises concerns about the long-term effectiveness of the treatment. Researchers are already planning to explore strategies to help sustain the benefits of CAR-T therapy in future trials.
One of the major hurdles in treating prostate cancer is that it is often considered immunologically “cold,” meaning that it tends to evade detection by the body’s immune system. As Dr. Tanya Dorff, a medical oncologist at City of Hope and the lead author of the study, explains, prostate cancer’s ability to hide from immune surveillance has made traditional immunotherapies less effective. However, CAR-T therapy, with its engineered precision, shows promise in overcoming these tumor defenses.
While these early findings are encouraging, there is still much more to learn. But as research continues to evolve, CAR-T immunotherapy may soon become a groundbreaking new treatment option for those battling prostate cancer.
