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Role of serum‐free light chain assay for defining response and progression in immunoglobulin secretory multiple myeloma
Author(s) -
Tacchetti Paola,
Rocchi Serena,
Zamagni Elena,
Barbato Simona,
Rizzello Ilaria,
De Cicco Gabriella,
Pantani Lucia,
Mancuso Katia,
Fusco Alessio,
Dozza Luca,
Ursi Margherita,
Favero Emanuele,
Terragna Carolina,
Testoni Nicoletta,
Cavo Michele
Publication year - 2022
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.26747
Subject(s) - medicine , immunofixation , multiple myeloma , immunoglobulin light chain , antibody , gastroenterology , progression free survival , oncology , monoclonal , overall survival , immunology , monoclonal antibody
The International Myeloma Working Group (IMWG) guidelines recommend using electrophoresis and immunofixation to define response and progressive disease (PD) in immunoglobulin (Ig) secretory multiple myeloma (Ig‐MM), whereas the role of serum‐free light chain (sFLC) is controversial. We retrospectively analyzed the value of adding sFLC assays in the definition of response and PD according to IMWG criteria in 339 Ig‐MM patients treated with a first‐line novel agent‐based therapy (median follow‐up 54 months). sFLC PD was defined according to conventional criteria plus increased sFLC levels, or sFLC escape (sFLCe); progression/sFLCe‐free survival (ePFS) was the time from the start of treatment to the date of first PD or sFLCe, or death; overall survival after PD/sFLCe (OS after Pe) was the time from first PD or sFLCe to the date of death. 148 (44%) patients achieved a complete response and 198 (60%) a normal sFLC ratio (sFLCR). sFLCR normalization was an independent prognostic factor for extended PFS (HR = 0.46, p = 0.001) and OS (HR = 0.47, p = 0.006) by multivariable analysis. 175 (52%) patients experienced PD according to the IMWG criteria, whereas 180 (53%) experienced PD or sFLCe. Overall, a sFLCe was observed in 31 (9%) patients. Median PFS and ePFS were both equal to 36 (95% CI = 32–42, and 32–40, respectively) months. sFLC PD adversely affected the OS after Pe compared to PD with increasing monoclonal Ig only (HR = 0.52, p = 0.012). Our results support the inclusion of the sFLC assay for defining response and PD in Ig‐MM.