NEW YORK (Reuters Health) - In patients with multiple myeloma, serum-free light-chain measurements are useful for disease monitoring even in patients who achieve only a partial response to therapy, according to a retrospective data analysis.
"Normalization of the serum-free light-chain ratio (FLCr) with the absence of bone marrow monoclonal plasma cells following achievement of a complete response (CR) to therapy denotes a stringent CR in multiple myeloma (MM), and is associated with improved overall survival (OS)," the study team notes online May 12 in Leukemia. "However, its value in patients achieving < CR is not clear."
Dr. Shaji Kumar and colleagues from the Mayo Clinic in Rochester, Minnesota, theorized that MM patients achieving a normalization of FLCr after initial therapy would have an improved outcome, even in the absence of a CR.
To test their theory, they took a look back at 449 patients with newly diagnosed MM with measurable disease at baseline, who did not achieve a CR with initial therapy; 153 (34%) had a normal FLCr, while 296 (66%) had an abnormal ratio.
In support of their theory, they found that patients with a normal FLCr had a longer progression-free survival (29 vs. 16 months, p<0 .001="" 58="" a="" and="" flcr="" in="" its="" model="" months="" multivariable="" of="" ormalization="" os="" p="" prognostic="" retained="" say.="" they="" value="" vs.="">
Limitations of the study include its retrospective nature and the lack of predefined schedules for response assessments, the researchers note. Also, it's based on patients seen at a referral center, and about 20% of them did not have baseline sFLC measurements.
Other limitations are the variety of the anti-myeloma therapies used as well as variable duration of the treatments. The researchers say they tried to limit the heterogeneity by examining the first response obtained after diagnosis in these patients.
"Despite these limitations, our study is the largest to date looking at the benefit of FLC in monitoring MM patients with intact immunoglobulin, and our results largely confirm the beneficial role of serial sFLC measurements in this group of patients," Dr. Kumar and colleagues say.
They conclude, based on their findings, that "obtaining a normal sFLC ratio confers a more favorable prognosis irrespective of the depth of the response, which may represent an effective eradication of a plasma cell subclone that secretes these free light chains. This would be consistent with the prior findings of inferior outcomes seen among patients with myeloma with higher levels of serum FLC at presentation."
"We suggest an important role for sFLC measurements in disease monitoring even in patients who achieve only a PR to therapy. Conceivably, this can be done at the time the patient achieves their maximal response to a given therapy (instead of serial measurements at every time point), and future studies should be designed to examine whether alterations in therapy based on these results will alter long-term outcomes. These results support the inclusion of sFLC at all levels of response included in the current IMWG criteria," they add.
The authors did not respond to request for comment by press time. The study had no commercial funding and the authors have no relevant disclosures.
SOURCE: http://bit.ly/1IKUmdN
Leukemia 2015.
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