Free Light Chains Allow Earlier Detection of MM Treatment Response

A research team from Stockholm, Sweden, evaluated whether serum-free light chains (FLC) could detect treatment response or disease progression in multiple myeloma (MM) earlier than standard methods.

The standard monitoring methods in MM are myeloma-protein measurements using serum and urine protein electrophoresis (sPEP/uPEP), according to the authors. However, serum FLC analysis, which is a complementary method used in diagnostics and follow-up, has a shorter half-life compared with these traditional methods, or two to six hours versus up to 21 days, respectively.

“Involved FLC (iFLC) analysis could, in a temporal fashion, be of higher value for earlier treatment evaluation and, thus enabling a potentially better clinical decision making,” explained the authors.

For this study, the researchers enrolled 450 patients with MM who were assessed via iFLC, sPEP, and/or uPEP after first-, second-, and third-line therapy. Assessments were conducted according to International Myeloma Working Group guidelines, or after every fourth week for iFLC and sPEP and every fourth to twelfth week for uPEP. Primary outcomes were time to response and progression.

The median time to partial response or better across all cohorts was detectable significantly earlier for patients monitored with iFLC compared with sPEP, or 1.94 months versus 5.39 months, respectively. In the first-line cohort, median time to response was detectable at 2.2 months for iFLC compared with 5.6 months for sPEP and 19.2 months for uPEP (P<0.001). Earlier detection was found for iFLC in both first- and second-line groups, although the difference was not statistically significant among the third-line cohort. There was also no significant difference in time to disease progression between iFLC or sPEP.

In conclusion, the authors wrote, iFLC “predicted [median] responses at least three months before sPEP, regardless of the line of the treatment. The early detection of response might benefit the patients through a dose reduction and/or limit the number of drugs used in combination, due to eventual side effects.”

Findings from this study were published in Leukemia & Lymphoma.