Utilizing the body’s natural born killers to take out blood cancers

Natural killer cells sound menacing, but they play a friendly role in keeping us healthy. And they might do much more in stopping cancer.

After years of diligent, groundbreaking research, MD Anderson physician-scientists are putting natural killer cells – NK cells for short – to work in a series of clinical trials for a variety of cancers through the cancer center’s Moon Shots Program™.

“These white blood cells are the scouts, the sentinels of our immune system,” says Elizabeth Shpall, M.D., professor of Stem Cell Transplantation and Cellular Therapy.

They’re constantly surveying our bodies for invading microbes and abnormal cells – the type that can become cancer if they aren’t already. Equipped with an array of detection techniques, natural killers also are heavily armed to deal with the threats they discover.

“They’re poised to kill. They can kill over and over again,” says Katy Rezvani, M.D., who is also a professor in the department. “That’s why we’re trying to harness them for cancer immunotherapy.”

To do that, Shpall, Rezvani and their colleagues have been systematically identifying and overcoming disadvantages that hinder NK cells as cancer-fighting tools.

High on the list: There aren’t enough of them – they make up only 10% to 15% of our blood cells – and they don’t persist, lasting only two to three weeks. And perhaps most importantly, by the time a patient’s cancer has matured, it’s already evolved ways to evade that patient’s NK cells, so cells from a donor are required.

To get donor cells, Shpall and her colleagues have tapped a resource that’s unique for a cancer center, an umbilical-cord blood bank. MD Anderson’s was established as a source of blood stem cells for patients with certain blood cancers. Today, the bank stores 27,000 units of cord blood cells donated by mothers from Houston-area hospitals.

This resource means there’s no need to search for donors willing to go through safety screening and cell collection. Another advantage:

The cord blood units have been thoroughly analyzed, so it’s simple to select a good match with high potential for expanding in the lab.

To increase the supply of cord blood NK cells, Shpall’s team applies a technique pioneered by researchers in MD Anderson’s Pediatrics department nearly a decade ago for patients needing their own supply of stem cells expanded. The technique makes it possible to isolate and stimulate the NK cells in the lab, increasing their numbers 200-to 500-fold.

These NK cells can be given to patients without fear of dangerous side effects like graft vs. host disease. NK cells have been given to hundreds of patients, and so far there have been no toxicities.

Having overcome two major barriers – the need for donor cells and lots of them – the team now is working on ways to genetically modify NK cells so they last longer, even though cord-blood-derived NK cells provide some improvement in lifespan.

And the team is looking to add specialized receptors to identify and destroy specific targets.

There are five clinical trials underway at MD Anderson to deploy NK cells against Hodgkin and non-Hodgkin lymphoma, several types of leukemia, myelodysplastic syndrome and multiple myeloma. Read more about the clinical trials in Conquest.