Micrograph showing MM
Tests used to assess treatment response in multiple myeloma (MM) may often produce confusing results after patients have undergone hematopoietic stem cell transplant (HSCT), a new study suggests.
The tests—serum protein electrophoresis/serum immunofixation electrophoresis (SPEP/SIFE) and serum free light chain assay (SFLCA)—can sometimes produce an oligoclonal pattern that can be mistaken for an M spike and suggest disease recurrence.
The study showed that this confusing result was significantly more likely to occur after patients underwent HSCT than after they received chemotherapy.
Gurmukh Singh, MD, PhD, of Augusta University in Augusta, Georgia, reported these findings in the Journal of Clinical Medicine Research.
For this study, Dr Singh looked at lab and clinical data on 251 MM patients treated from January 2010 to December 2016. One hundred and fifty-nine of those patients received autologous HSCTs.
Dr Singh compared results of SPEP/SIFE and/or SFLCA in patients who underwent HSCT and patients who did not. Each patient had at least 3 tests, and, for HSCT recipients, at least 2 of the tests occurred after transplant.
The incidence of oligoclonal patterns was significantly higher in HSCT recipients than in patients who had chemotherapy alone—57.9% and 8.8%, respectively (P=0.000003).
Only 5 of the 159 HSCT recipients had an oligoclonal pattern before treatment, but 92 of them had one afterward.
More than half of the oligoclonal patterns developed within the first year of HSCT. The earliest pattern was detected at 2 months—as soon as the first post-transplant tests were done—and a few occurred as late as 5 years later.
“We want to emphasize that oligoclonal bands should mostly be recognized as a response to treatment and not be mistaken as a recurrence of the original tumor,” Dr Singh said.
He explained that the key clarifier appears to be the location of the M spike when the diagnosis is made compared to the location of new spikes that may show up after HSCT.
“If the original peak was at location A, now the peak is location B, that allows us to determine that it is not the same abnormal, malignant antibody,” he said. “If it’s in a different location, it’s not the same protein. [T]his is just a normal response of recovery of the bone marrow that could be mistaken for recurrence of the disease.”
