Table 1.
Patients characteristics.
| Variable | MRD positive (N = 50) N (%)/median (IQR) | MRD negative (N = 42) N (%)/median (IQR) | P value |
|---|---|---|---|
| Male sex | 33 (66) | 21 (50) | 0.128 |
| Age at diagnosis, years | 59 (55–66) | 61 (55–68) | 0.280 |
| Organ involvement at diagnosis | |||
| Heart | 36 (67) | 23 (54) | 0.093 |
| Kidney | 30 (60) | 31 (73) | 0.172 |
| Liver | 11 (22) | 4 (9) | 0.117 |
| Cardiac stage at diagnosis | (Available in 45 patients) | (Available in 40 patients) | |
| I | 11 (24) | 17 (43) | 0.084 |
| II | 18 (40) | 12 (30) | 0.341 |
| IIIa | 15 (34) | 9 (22) | 0.227 |
| IIIb | 1 (2) | 2 (5) | 0.582 |
| Renal stage at diagnosis | (Available in 41 patients) | (Available in 39 patients) | |
| I | 20 (49) | 18 (46) | 0.818 |
| II | 18 (44) | 18 (46) | 0.843 |
| III | 3 (7) | 3 (8) | 0.951 |
| eGFR, mL/min per 1.73 m2 | 86 (61–90) | 76 (60–89) | 0.158 |
| BMPC at diagnosis (%) | 8 (4–14) | 9 (4–15) | 0.865 |
| dFLC at diagnosis, mg/L | 141 (65–-488) | 112 (34–397) | 0.303 |
| Exposure to two lines of therapy before aCR | 25 (50) | 15 (36) | 0.177 |
| Time from diagnosis to first aCR documentation, months | 10 (6–15) | 11 (5–19) | 0.823 |
| Time from first aCR documentation to MRD assessment, months | 13 (5–30) | 12 (6–37) | 0.368 |
| Autologous stem cell transplant | 19 (38) | 16 (38) | 0.991 |
| Melphalan | 23 (46) | 14 (33) | 0.227 |
| Bortezomib | 45 (90) | 36 (86) | 0.547 |
| Cardiac response at the time aCR was documented | 16/29 (55) | 15/21 (71) | 0.262 |
| Renal response at the time aCR was documented | 12/29 (41) | 19/31 (61) | 0.470 |
Cardiac stage is defined by N-terminal pro-natriuretic peptide type B (NT-proBNP, cutoff 332 ng/L) and cTnI (cutoff 0.1 ng/mL), with stages I–III patients having none, one, or to markers above the cutoff, respectively. Stage IIIa patients have NT-proBNP <8500 ng/L. Stage IIIb patients have NT-proBNP >8500 ng/L. Renal stage is defined by eGFR (cutoff 50 mL/min per 1.73 m2) and proteinuria (cutoff 5 g/24 h); stage I patients have both eGFR above and proteinuria below the cutoff, stage II have either eGFR below or proteinuria above the cutoff, and stage III patients have both eGFR below and proteinuria above the cutoff.
eGFR estimated glomerular filtration rate, dFLC difference between involved (amyloidogenic) and uninvolved free light chain, aCR amyloid complete response defined by negative serum and urine immunofixation and normal free light chain ratio, BMPC bone marrow plasma cell infiltrate, MRD minimal residual disease.