Multicentered patient-based evidence of the role of free light chain ratio normalization in multiple myeloma disease relapse.

INTRODUCTION

The normalization of free light chain ratio (FLCr) has been introduced as a marker of stringent complete remission (CR) of multiple myeloma (MM). There is currently a lack of literature assessing the role of FLCr on MM disease progression and remission status.

PATIENTS AND METHODS

A multicentered retrospective review of 125 patients with MM in CR and various FLCr values was completed. Parameters of interest included patient demographics, FLCr values, complete remission (CR)/relapse status, and time to progression (TTP). The FLCr values were recorded to provide time-dependent findings on the role of FLCr on progression-free survival and overall survival (OS).

RESULTS

The mean follow-up time of 125 patients from five hospitals in the Czech Republic was 31 months. A total of 47.2% of patients relapsed (54 of 125) during the follow-up period. The median TTP of patients with normal FLCr (n = 66) was 54.4 and 40.2 months for patients with abnormal FLCr (n = 59) (P = 0.217). None of the patients reached median overall survival regardless of FLCr values (P = 0.821). In the subgroup of newly diagnosed patients after upfront autologous stem cell transplantation (ASCT), there were 55.6% of patients (35 of 63) with normal FLCr and 44.4% (28 of 64) with abnormal FLCr. A total of 34.9% of patients (22 of 63) relapsed in this subgroup. Within the abnormal FLCr patients, a median TTP was 56.3 months, but no median TTP was reached among the normal FLCr patients (P = 0.746). Median OS in patients with normal (nFLCr) and abnormal FLCr (aFLCr) was not reached (P = 0.787).

CONCLUSION

We did not observe any benefit from FLCr normalization in CR in myeloma patients in terms of progression-free survival or overall survival.