New drug shows potential for blood cancer
Elotuzumab works against this relatively rare cancer through a dual mechanism, said senior study author Dr. Sagar Lonial. It makes cancer cells vulnerable to immune attack, and also enhances the immune system's ability to kill cancer.
"It's a bit of a double-whammy," said Lonial, executive vice chair of hematology and oncology at Emory University School of Medicine in Atlanta.
Patients receiving the three-drug elotuzumab cocktail did not seem to suffer an increase in side effects, compared with those who took the two-drug standard regimen.
Elotuzumab is being developed by Bristol-Meyers Squibb and AbbVie Pharmaceuticals, which helped fund the study. The findings were presented Tuesday at the American Society of Clinical Oncology annual meeting in Chicago and published in the New England Journal of Medicine.
Multiple myeloma is caused by malignant plasma cells in the bloodstream and bone marrow, according to the U.S. National Institutes of Health. Myeloma patients tend to suffer bone pain and easily broken bones, weakness or fatigue, weight loss, and frequent infections.
About 26,850 new cases of myeloma are expected to occur this year, according to the American Cancer Society. More than 11,000 are expected to die from myeloma in 2015.
The standard therapy for myeloma involves the chemotherapy drug lenalidomide and the steroid medication dexamethasone, Lonial said.
But researchers wondered if they'd get better results by adding the experimental drug elotuzumab. In 2014, the drug was granted a breakthrough therapy designation by the U.S. Food and Drug Administration for treatment of relapsed multiple myeloma alongside lenalidomide and dexamethasone. This designation is intended to speed up the development and review of drugs for serious or life-threatening conditions.
Elotuzumab, administered by intravenous infusion, targets a protein called SLAMF7, which is found on the surface of myeloma cells and also on a type of immune cell called natural killer cells.
In the study, 646 patients with recurring, already treated myeloma received the standard two-drug treatment. About half also received elotuzumab.
At an average follow-up period of 24 months, elotuzumab reduced risk of cancer progression and death by 30 percent, researchers found.
Patients in the elotuzumab group experienced a longer period of remission, about 19.4 months on average compared with 14.9 months for those who had standard treatment.
The three-drug cocktail also produced a response rate of 79 percent, compared with 66 percent for the standard treatment, the study found.
"Patients who received elotuzumab had a longer duration of remission, had a higher overall response rate, and this improvement in clinical parameters occurred without a significant increase in adverse events or toxicity," Lonial said.
The most common side effects experienced by both groups of patients were anemia, low levels of white blood cells and platelets, fatigue and diarrhea. Mild infusion reactions occurred after the first few doses in 10 percent of patients in the elotuzumab group.
Elotuzumab represents the first potentially effective immunotherapy drug for myeloma, said Dr. Julie Vose, president-elect of the American Society of Clinical Oncology. Benefits without additional side effects are being seen even in patients who have received multiple prior treatments for their cancer, said Vose, professor of hematology and oncology at the University of Nebraska Medical Center.
"The results are very encouraging, giving renewed hope to patients who have relapsed," Vose said.
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