The findings from a new research study conducted by scientists from the Fred Hutchinson Cancer Research Center in Seattle Washington, was revealed earlier this month. During an annual meeting, the researchers discussed the progress that had been made in the development of an immunotherapy for ovarian cancer. They also outlined the eminent challenges that must be addressed, before the immunotherapy can be made effective for treating cancers with solid tumors, such as ovarian cancer.
According to the American Cancer Society, an estimated 22,440 women in the United States will be diagnosed with ovarian cancer in 2017. An estimated 14,000 women, who have been diagnosed with the disease, will die in 2017. Ovarian cancer is less common in the United States than other types of cancer that have solid tumors. However, it has a high rate of relapse and low rate of survival, because the woman will remain asymptomatic (exhibits no symptoms) and diagnosis will not occur until the disease is advanced.
Ovarian cancer starts in the cells of reproductive glands or ovaries. Normally, women will have a set of ovaries, which are situated inside the pelvis on each side of the uterus. These glands are responsible for producing eggs that make a long journey through the fallopian tubes to the uterus and if they become fertilized by spermatozoon, it will develop into a fetus.
Immunotherapy is a fairly a new area of medicine, but it is showing encouraging results in the treatment of cancer. The treatment involves utilizing the body’s own immune system to combat the disease.
The new study focuses on adoptive T cell (an immune cell) transfer, which involves removing T cells from the patient or another individual’s blood and reprogrammed to attack and destroy the cancer cells. The primed cells will then be returned to the patient’s body.
An immunotherapy researcher at Fred Hutch, Dr. Kristin Anderson, has reported significant success in utilizing adoptive T cell transfer for treating blood cancers.
The research team discovered that ovarian cancer cells produce too many mesothelin and WT1 proteins and in the laboratory, the T cells modified to attack them can annihilate both mice and human ovarian cancer cell.
They also discovered that mice with ovarian cancer induced with modified T cells showed increased survival.
The researchers note that T cell transfer is not ready for clinical trials in human patients and has a way to go before it will be.
During the study, it was discovered that it was easier to treat blood cancers with T cell therapy, compared to solid tumors, like ovarian, breast, pancreatic and lung cancers.
In lymphoma and leukemia, the modified T cells can be infused into the bloodstream, where they can attach the blood cancer, but accessing solid tumors tucked inside the body is much more challenging. Tumor microenvironment, a mixture of molecules, extracellular matrix and noncancerous cells in and around the tumor, is only one example.
Tumor microenvironment poses three separate challenges, which is something the researchers are working on. Proteins and cells inside the tumor microenvironment send signals to T cells telling to ignore or shut down the tumor cells. However, the researchers suggest utilizing checkpoint inhibitors, existing drugs designed to weaken checkpoint proteins. Another option is T cells could also be engineered to block these signals.
Another challenge is ovarian tumor cells and nearby blood vessels transmit “self-destruct” signals to T cells, which in turn causes the T cells to attack themselves before they can target the cancer cells. The solution to this issue may be to utilize a fusion protein to boost T cell anticancer activity, when they receive these self-destruct signals.
The third challenge that has been identified in the solid tumor microenvironment is the issue of low sugar. In order for the ovarian cancer cells to grow at a rapid pace they need sugar, which comes from their environment. Modified T cells also require this sugar for fuel, so they can travel to and attack the cancer cells. The research team is currently working on another suitable source of energy for the engineered T cells.
“If we can solve some of these issue that really plague us with hard one, then we can more readily apply (the solutions) to cancers that have fewer of these hurdles,” Dr. Anderson says.