Nearly 20% of patients with multiple myeloma have a form of the disease in which they make high quantities of a component of monoclonal proteins, which damages the kidneys.
Among patients with multiple myeloma, new research has linked severe kidney damage with shorter survival times, according to investigators at the Medical College of Georgia at Augusta University.
Multiple myeloma causes plasma cells to become abnormal and begin producing a single, Y-shaped protein called a monoclonal protein, or M-spike. These proteins can cause damage throughout the body and have 2 chains, called heavy and light chains. The disease is classified based on the type of each of these chains it produces, according to the study.
Nearly 20% of patients with multiple myeloma have a form of the disease in which they make high quantities of a component of monoclonal proteins found in free monoclonal light chains, the experts said. Some patients, such as those being studied by researcher Gurmukh Singh, MD, PhD, produce even more light chains.
Because these light chains do not have heavy chain proteins to pair with, Singh said a lot more chains are free and circulating throughout the body. This circulation allows them to accumulate in the kidneys, according to the study. Singh and his colleagues investigated these effects by analyzing nearly 400 patients from a 10-year period to assess why these patients typically have a shorter survival time.
According to the press release, these patients have higher rates of kidney dialysis and clear signs of kidney damage, such as higher blood pressure and higher concentrations of protein in the urine. Furthermore, mortality rates in these patients were nearly 3 times higher than for patients with conventional multiple myeloma. Singh described the survival graph for most patients as a gradual hill, whereas the graph for patients with this form of the disease looked like a cliff.
These shorter survival rates were clearly associated with kidney damage caused by the buildup of light chains in their blood and kidney tubules, which carry urine away from the filtering units and are where necessary things such as salt and water get resorbed, Singh said.
In addition to requiring dialysis, more of these patients also needed blood transfusions to help supplement the effects of their bone marrow, which was also under attack from the abnormal plasma cells. The patients also had higher rates of hypertension, which can both damage the kidneys and result from kidney damage. Although multiple myeloma tends to impact the kidneys in all patients, this subset with excessive light chains appears to have worse damage, according to the study.
Patients with this form of multiple myeloma could benefit from early identification and additional interventions, such as plasmapheresis and dialysis, which would remove the damaging light chains. However, Singh said clinical trials are needed to evaluate these and other strategies.
Singh added that although tests can identify individuals with this subtype of multiple myeloma, there are currently no treatments once they are identified. In healthy individuals, these excess light chains are simply filtered out by the kidneys and eliminated in the urine; however, in this form of multiple myeloma, “Everything is multiplied, the kidneys get bombarded, and the tubules get clogged,” Singh said in the press release.
Finding ways to quickly identify and treat this issue in patients with multiple myeloma is a major goal for researchers.
Patients with multiple myeloma with the shortest survival have the most kidney damage. News release. Augusta University; August 31, 2021. Accessed September 2, 2021. https://jagwire.augusta.edu/patients-with-multiple-myeloma-with-the-shortest-survival-have-the-most-kidney-damage/