Researchers at the Mayo Clinic in Rochester, Minnesota, have presented data to show that the monoclonal antibody daratumumab, which targets the CD38 protein, significantly reduces the risk of smoldering multiple myeloma (SMM) progressing to active multiple myeloma. The results of the AQUILA phase III clinical trial, published in the New England Journal of Medicine, were presented this week at the American Society of Hematology (ASH) meeting in San Diego and offer new hope for patients with high-risk SMM, who previously had few treatment options.
Smoldering multiple myeloma is a pre-cancerous, slow-growing stage of multiple myeloma characterized by the accumulation of abnormal plasma cells in the bone marrow. SMM is asymptomatic and is often first suspected from high protein levels in detected in a person’s routine blood test.
High-risk SMM is characterized by higher levels of urinary M protein, the type of M protein present, and a condition called immunoparesis—when one or more uninvolved immunoglobulins are suppressed, increasing the likelihood of progression to active disease. Patients with high-risk SMM are typically monitored closely by their physicians and may be considered for clinical trials or more aggressive treatments.
Daratumumab, first approved by the FDA in 2015 for the treatment of active multiple myeloma, works by targeting CD38, a protein found on the surface of myeloma cells. By binding to CD38, daratumumab triggers the immune response to attack myeloma cells.
The AQUILA trial enrolled 390 patients, randomly assigning 194 to receive subcutaneous daratumumab and 196 to an active monitoring cohort. After a median follow-up of 65.2 months, the results were striking. Daratumumab treatment resulted in a 51% reduction in the risk of disease progression or death compared to active monitoring (hazard ratio, 0.49). At five years, 63.1% of patients receiving daratumumab remained free from progression, compared to only 40.8% in the active-monitoring group. Moreover, survival at five years was significantly better in the daratumumab group at 93% compared with 86.9% in the monitoring group.
“These results are a major advancement in the treatment of high-risk smoldering multiple myeloma,” said lead investigator S. Vincent Rajkumar, MD, a hematologist at the Mayo Clinic Comprehensive Cancer Center. “For the first time, we have a treatment option that can significantly delay or prevent the progression to active disease, improving the lives of patients and offering them a chance at a longer, healthier future.”
The most common grade 3 or 4 adverse event was hypertension, which occurred in 5.7% and 4.6% of the patients in the daratumumab group and the active-monitoring group, respectively. Adverse events led to treatment discontinuation in 5.7% of the patients in the daratumumab group, and no new safety concerns were identified than had been found in earlier trials of the drug.
