After stem cell therapy, profiles may show a pattern of antibodies that can look very much like the “M spike”—the signature of the monoclonal antibody produced by multiple myeloma (MM). But that pattern, called an oligoclonal band, can be misleading.
“Oligoclonal bands should mostly be recognized as a response to treatment and not be mistaken as a recurrence of the original tumor,” says Dr. Gurmukh Singh, vice chair of clinical affairs for the Department of Pathology at the Medical College of Georgia at Augusta University.
He and his research team analyzed data from 251 patients with MM, 159 of whom had received autologous stem cell transplants. The researchers performed tests using serum protein electrophoresis/serum immunofixation electrophoresis and serum free light chain assay. Each patient had at least 3 tests, with at least 2 following the transplant.
The researchers found the incidence of oligoclonal patterns was dramatically higher in patients who had a stem cell transplant, compared with patients who had chemotherapy alone (57.9% vs 8.8%). Moreover, only 5 of the 159 patients who received a transplant had an oligoclonal pattern before treatment, but 92 had 1 afterward. More than half the oligoclonal patterns developed within the first year following transplant. The earliest pattern was detected at 2 months and a few as long as 5 years later.
The key to assessing response, Singh says, is to see where the spike appears: that is, where the monoclonal spike is at diagnosis compared with any new spikes that appear in oligoclonal bands after stem cell treatment. “If the original peak was at location A, [and] now the peak is location B, that allows us to determine that it is not the same abnormal, malignant antibody.”
The finding that 58% of patients had the oligoclonal pattern after transplant is likely an underestimate due to irregular schedule of testing, the researchers say. They add that their findings highlight the need for higher resolution electrophoretic methods to obviate the need for using mass spectrometry for clinical samples. Their results “cast more doubt on the clinical usefulness and medical necessity of the serum free light chain assay.”
Baker T. Results after stem cell transplant can confuse patients and doctors about cancer’s status. Jagwire News. https://jagwire.augusta.edu/archives/46434. Published August 2017. Accessed September 20, 2017.
Singh G. J Clin Med Res. 2017;9(8):671-679.