What Are Some of the Challenges In Creating a Vaccine for Cancer?

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[BLANK-AUDIO] Well we haven't found ways to stimulate those very rare cells that are in the body that are recognizing the cancer, and so although it's a promising approach that has been used effectively to prevent viral infections, but we haven't been able to develop vaccines that will actually stimulate T cells that will eliminate or reduce cancers that already exist.

Now the third form of immunotherapy is called Adoptive T cell Therapy or Adoptive Cellular Therapy, and that therapy we identify the exact immune lymphocytes, the immune warriors of the body that can recognize a cancer. We take them out of the body, we either educate them or genetically engineer them so that they can recognise the cancer and then we return them under conditions that allow them to work.

That is we have to first eliminate the body's natural immune system to make room for the new cells we give. And when we do that, we can see response rates in patients with melanoma that are higher than any kind of cancer treatment. In one trial, we had 72% of our patients with metastatic melanoma undergo objective regressions and 40% of those had complete durable regressions ongoing beyond 5 years and we have some beyond 10 years.

Now this therapy has been used in patients with melanoma quite effectively, it's an experimental treatment, but we've developed ways to genetically engineer lymphocytes. That is take out normal lymphocytes and put in receptors that can recognise a cancer, and we first reported that in 2010 as a treatment for patients with lymphomas, targeting a CD19 molecule, not a mutation.

But in normal molecule that's on B cells, but that's also expressed in over 90% of lymphomas and Leukemias. And so you can genetically engineer a lymphocyte for patients that have advanced refractory lymphomas or leukemias and give them back. And they can then cause regressions and often complete regressions and the first patient ever treated this way.

In 2010 one of our patients here at the NCI is still progression free now five years later. So one can use the patient's natural cells or you can generically engineer them to attack the cancer.