Comparison of serum free light chain and urine electrophoresis for the detection of the light chain component of monoclonal immunoglobulins in light chain and intact immunoglobulin multiple myeloma

Diagnosis and monitoring for light chain only and oligosecretory myeloma using serum free light chain tests

“…In the present study, 24‐h urine was not available and urine electrophoresis and IFE (as recommended for monitoring by IMWG uniform response criteria [Durie et al , ]) were not included as comparison with sFLC quantitation at follow‐up. Evidence indicates that measuring changes in FLC levels in serum provides a more sensitive indicator of disease activity than changes in urine (Drayson et al , ; Bradwell et al , ; Dejoie et al , ,b) and the addition of normalisation of sFLC levels for a stringent CR in current guidelines adds that important improved sensitivity for LCO patients (Durie et al , ; Dispenzieri et al , ; Rajkumar et al , ; Kumar et al , ). Importantly, a recent study demonstrated that response evaluated by sFLC measurements had greater prognostic significance in LCO patients than urine IFE and electrophoresis (Dejoie et al , ).…”

“…sFLC testing has subsequently been incorporated into the International Myeloma Working Group (IMWG) Guidelines for diagnosis and management of all plasma cell dyscrasias (Durie et al , ; Dispenzieri et al , ). However, these guidelines still recommend the use of uFLC for measurement of response to therapy if available because there is insufficient published data to advocate replacement with sFLC testing, although the evidence is increasing (Dejoie et al , ,b). Further, it is not clear how sFLC levels at diagnosis and in response to therapy compare between patients with measurable disease in urine and those with low or undetectable uFLC levels.…”

Serum free light chains and multiple myeloma: Is it time to extend their application?

“…In this specific population, sFLC offers a distinctive advantage over serum IFE to detect disease progression, particularly in IgG MM patients. The conclusion is that oligo‐secretory patients should be controlled routinely with both SPEP and sFLC tests . In the meantime, different modified response assessments, including FLC assay, have been proposed, such as inclusion of rFLC and dFLC in response criteria and abnormal rFLC and iFLC level with further iFLC increase >50% as a marker of disease progression …”

“…9 Although the IMWG response criteria are widely used in every line of therapy, there are no clinical data that confirm the validity of this evaluation from the second line of therapy onwards. Moreover, to date there have been several studies that have validated the usefulness of serial FLC measurements with rFLC and differential FLC (dFLC) in MM population, especially in OS, NS, and LC MM with poor prognosis, 11,12,[15][16][17][18] but currently there are no prospective studies performed in the era of novel agents.…”

“…The conclusion is that oligo-secretory patients should be controlled routinely with both SPEP and sFLC tests. 15 In the meantime, different modified response assessments, including FLC assay, have been proposed, such as inclusion of rFLC and dFLC in response criteria 16 and abnormal rFLC and iFLC level with further iFLC increase >50% as a marker of disease progression. 18 There has been experience of clonal evolution, with a switch in the monoclonal protein subtype (light chain conversion), described recently also by our group.…”