Medical researchers at the Johns Hopkins Kimmel Cancer Center have published a report that appeared in the journal Science Translational Medicine in which they describe, for the first time, the safe use of a patient’s own immune cells to treat the white blood cell cancer multiple myeloma. There are more than 20,000 new cases of multiple myeloma and more than 10,000 deaths each year in United States. It is the second most common cancer originating in the blood.
The procedure under investigation in this study is called utilizes a specific type of tumor-targeting T cells, known as marrow-infiltrating lymphocytes (MILs). “What we learned in this small trial is that large numbers of activated MILs can selectively target and kill myeloma cells,” says Johns Hopkins immunologist Ivan Borrello, M.D., who led the clinical trial.
According to Borrello, MILs are the foot soldiers of the immune system that attack invading bacteria or viruses. Unfortunately, they are typically inactive and too few in number to have a measurable effect on cancers.
Experiments conducted is Borrello’s laboratory and in the laboratory of competing and collaborating scientists have shown that when myeloma cells are exposed to activated MILs in culture, these cells could not only selectively target the tumor cells, but they could also effectively destroy them.
To move this procedure from the laboratory into the clinic, Borrello and his collaborators enrolled 25 patients with newly diagnosed or relapsed multiple myeloma. Only 22 were able to receive this new treatment, however.
The Hopkins team extracted and purified MILs from the bone marrow of each patient and grew them in the laboratory to increase their numbers. Then they activated the MILs by exposing them to microscopic beads coated with immune activating antibodies. These antibodies bind to specific cell surface proteins on the MILs that induce profound changes in the cells. This induction step wakes the MILs up and readies them to sniff out tumor cells. These laboratory-manipulated MILs were then intravenously injected back into each patient (each of the 22 patients with their own cells). Three days before these injections of expanded MILs, all patients received high doses of chemotherapy and a stem cell transplant, which are standard treatments for multiple myeloma.
One year after receiving the MILs therapy, 13 of the 22 patients had at least a partial response to the therapy (their cancers had shrunk by at least 50 percent) Seven patients experienced at least a 90 percent reduction in tumor cell volume and lived and average of 25.1 months without cancer progression. The remaining 15 patients had an average of 11.8 progression-free months following their MIL therapy. None of the participants experienced serious side effects from the MIL therapy.
According to Borrello, several U.S. cancer centers have conducted similar experimental treatments (adoptive T cell therapy). However, only this Johns Hopkins team has used MILs. Other types of tumor-infiltrating cells can be used for such treatments, but Borrello noted that these cells are usually less plentiful in patients’ tumors and may not grow as well outside the body.
In nonblood-based tumors, such as melanoma, only about half of those patients have T cells in their tumors that can be harvested, and only about one-half of those harvested cells can be grown. “Typically, immune cells from solid tumors, called tumor-infiltrating lymphocytes, can be harvested and grown in only about 25 percent of patients who could potentially be eligible for the therapy. But in our clinical trial, we were able to harvest and grow MILs from all 22 patients,” says Kimberly Noonan, Ph.D., a research associate at the Johns Hopkins Universithttp://www.fiercevaccines.com/special-reports/gvax-pancreasy School of Medicine.
This small trial helped Noonan and her colleagues learn more about which patients may benefit from MILs therapy. As an example, they were able to determine how many of the MILs grown in the lab were specifically targeted to the patient’s tumor and whether they continued to target the tumor after being infused. They also found that patients whose bone marrow before treatment contained a high number of certain immune cells, known as central memory cells, also had better response to MILs therapy. Patients who began treatment with signs of an overactive immune response did not respond as well.
Noonan says the research team has used these data to guide two other ongoing MILs clinical trials. Those studies, she says, are trying to extend anti-tumor response and tumor specificity by combining the MILs transplant with a Johns Hopkins-developed cancer vaccine called GVAX and the myeloma drug lenalidomide, which stimulates T cell responses.
These trials also have elucidated new ways to grow the MILs. “In most of these trials, you see that the more cells you get, the better response you get in patients. Learning how to improve cell growth may therefore improve the therapy,” says Noonan.
Kimmel Cancer Center scientists are also developing MILs treatments to address solid tumors such as lung, esophageal and gastric cancers, as well as the pediatric cancers neuroblastoma and Ewing’s sarcoma.
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