Natural Killer Cells Could Be Used to Treat Myeloma, Small Study Suggests

A new immunotherapy using natural killer cells showed promise in a small proof-of-concept Phase 1 trial of relapsed or refractory multiple myeloma patients who also received anti-myeloma treatment.

Although the trial suggested the treatment is safe and effective, larger studies are needed to determine if the cells really help patients with advanced myeloma and generate side effects not detected in the small study.

The research, “Novel treatment strategy with autologous activated and expanded natural killer cells plus anti-myeloma drugs for multiple myeloma,” was published in the journal Oncoimmunology.

The study (NCT02481934), performed by researchers at the 12 October University Hospital in Spain, involved five patients who had gone through several rounds of treatment. Three were treated with Revlimid (lenalidomide) and two with Velcade (bortezomib) throughout the study.

The team said abnormal immune processes in multiple myeloma likely prevent natural killer cells from attacking the tumors. Normally the cells are efficient at killing infected or abnormal cells, but myeloma tumors suppress their immune activity — as is the case with many cancers.

In an attempt to re-activate the killer cells, researchers first extracted some from patients. They kept them together with lab-grown cells derived from human leukemia for three weeks.

The presence of the other cell type prompted the natural killer cells to regain their immune activity, researchers learned. The team then put the cells back into patients. Four patients received two infusions each, and one patient four infusions.

The activated cells ended up in the blood and bone marrow of the patients, the team discovered. The condition of four of the five patients stabilized by the end of treatment. Two patients had a significantly lower bone marrow infiltration of cancer cells — a response that held than a year after treatment.

Importantly, the treatment did not lead to complications. Two patients had lower counts of neutrophils, or white blood cells, but researchers concluded that the lack of these cells was caused by chemotherapy.

Measuring the number of activated natural killer cells in patients’ blood between the first and second infusions, researchers noted a difference in how they had multiplied. In patients who were treated with Velcade, the infused cells increased by 15.2 percent, versus a 0.4 percent increase in those treated with Revlimid.