Methods of Treatment of Cancer by Dendritic Cells and Dendritic Cell Vaccines

So, what can you do to get dendritic cells to hand off information about your tumor cells to your CTLs?

Vaccination with autologous [derived from the person's own body] dendritic cells generated from peripheral blood is a safe and promising approach in the treatment of cancer, including metastatic cancer. There are little to no side effects from such therapy.

There is a compelling evidence that dendritic cells may hold a key position in effective, non-toxic treatments for cancer.

In clinical practice for such treatment it is necessary to:

  • Produce large numbers of dendritic cells from the circulating blood of cancer patients in cell culture, such as developed by FCTI;

  • Find the source of tumor material (antigen) for each type of tumor that will best stimulate the T cells to proliferate and kill tumor cells; and

  • Stimulate the dendritic cells already in and around the tumor to mature, and become better T cell stimulators.

1. Dendritic Cells Treated With Patient's Own Tumor Material

Before beginning on this protocol, patients must first provide tumor tissue to the laboratory for use with the dendritic cells. Arrangements are made with your surgeon, prior to surgery for proper collection and transport of the tumor material to the laboratory. At the laboratory, an extract of the tumor tissue is made, and then filtered to make it sterile.

FCTI uses the patient's own tumor material (if available, which is rare) and own dendritic cells. Monocytes are first harvested from the circulating blood using either a an apheresis (Greek for to take out) unit commonly used by the blood transfusion service, but otherwise rarely available. The procedure is relatively simple. A needle connected to sterile, one-use tubing is placed into each arm. The tubing is connected to the machine, and approximately one cup of blood is circulated out of one arm, through the machine, and back into the other arm. The machine spins the blood, removes two types of white blood cells, and returns the fluid part of the blood and all of the other blood cells to the patient. Using this machine allows for many more white blood cells to be collected than by simply drawing blood because the other cells are returned to the patient. The procedure takes about two hours.

Under normal circumstances FCTI collects 30 ml of patient's blood is collected in EDTA vials. In FCTI manufacturing facility leukocytes are separated and counted by FACS cell sorter, washed, and planted on cell culture.

After 10 - 11 days  dendritic cells become visible under inverted microscope. Two days later the filtered tumor extract is added to the cell culture medium. The cells are then allowed to mature for another 7 days.

The cells are then tested for their maturity and purity. They are then frozen in liquid nitrogen and are ready to be reinfused.

A portion of the cells will then be suspended in sterile saline and reinfused intraveneously (by a vein in the arm) into the patient. The patient will receive an infusion once or twice per month.

After the cells are infused, some will migrate to the lymph nodes and some will stay in the circulation. The likelihood is high that many of the dendritic cells will come in contact with T-lymphoctyes (CTL's) and stimulate them to divide and recognize and kill tumor cells. Measuring the serum levels of specific tumor marker can allow your doctor to follow the course of prostate cancer. This test is used to determine if the treatment has been effective.

2. Dendritic Cells Treated With Purified Tumor Antigen

This procedure is the same as number one with one exception. The agent used to prime or activate the dendritic cells is not an extract of the patient's own tumor. Instead, a known tumor antigen (molecule that has information about the outside of tumor cells) is placed with the dendritic cells while they grow and mature in culture. Specific tumor marker is used.

Measurement of the serum levels of PSA will also be used to determine if the treatment has been effective.

3. Stimulation of Immature Dendritic Cells to become Mature Dendritic Cells

In many types of tumors the dendritic cells in and around the tumors are immature meaning they are there, they just can not effectively pass along information about the tumor cells to the rest of the immune system, in particular to the CTL's, or T-lymphocytes.

One way to convert immature dendritic cells into mature ones is by using a mixture of growth factors and stimulating factors called cytokines. These growth factors are found naturally in the body and can be manufactured using a patient's own white blood cells. The monocytes, when mixed with a medication made from bacterial cell walls, can produce an effective mixture of cytokines. The monocytes are mixed with the medicine and grown in an incubator for 2 days. Then the culture medium is collected. It contains a lot of cytokines. We call this mixture MCM, which stands for monocyte-conditioned-medium. When MCM is placed with immature dendritic cells, a majority of them become mature. They can then migrate and effectively convey information about the tumor to lymphocytes, stimulating them to divide at the same time.

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