Table 2.
Methodology and findings of published flow cytometry-based MRD studies in AL amyloidosis and of the present report.
| Study | NGF technique | Sensitivity | N. pts | Pts. in CR N (%) | ASCT N (%) | Eligibility criteria | Median time from CR to MRD assessment | MRDpos N (%) | Median follow-up from MRD assessment | % Hematologic progression POS vs NEG | Cardiac response N/evaluable (%) POS vs NEG | Renal response N/evaluable (%) POS vs NEG |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Kastritis et al.24 | EuroFlow |
Range: 2–3.1 × 10−6 Median 2.3 × 10−6 |
20 |
20 (100%) |
8 (40%) |
CR+ negative BM biopsy | 36 months |
12 (60%) |
NA | NA | 1/4(25%) vs 3/3(100%) |
6/10(60%) vs 6/8 (75%) |
| Muchtar et al.26 | 7-color MFC |
Range: 1 × 10−4–2 × 10−5 |
82 |
16 (20%) |
69 (84%) |
End of first-line treatment | NA |
58 (71%)a Subgroup of CR pts.: 8 (50%) |
NA |
3-year PFS: 28% vs 88% Subgroup of CR pts.: 33% vs 100% |
Subgroup of VGPR/CR pts.: 10/12 (83%) vs 8/8 (100%) |
Subgroup of VGPR/CR pts.: 13/19 (68%) vs 14/14 (100%) |
| Sidana et al.25 | Euroflow | Range: ≥1 × 10−5–10−6 | 44 |
20 (45%) |
25 (57%) |
MRD testing within 2 years from start of therapy | NA |
14 (36%)b Subgroup of CR pts.: 5 (25%) |
14 months |
Estimated 1-year PFS: 64% vs 100% |
2/7 (22%) vs 8/12 (67%) |
8/9 (89%) vs 11/16 (69%) |
| Staron et al.28 | 2-tube, 10-color antibody panel | Range: 1 × 10−4–1 × 10−5 | 65 | 65 (100%) | 32 (49%) | CR at previous evaluation |
71 months for MRD negative 32 months for MRD positive |
36 (55%) | NA | NA | 10/17 (59%) vs 9/12 (75%) | 18/28 (64%) vs 21/24 (88%) |
| Kastritis et al.27 | Euroflow | Range: 2 × 10−6–3.1 × 10−6 | 52 | 52 (100%) | 7 (14%) | CR after their primary therapy | 6 months (range 3–12) | 28 (55%) | 24 months | 21% vs 0% | 11/15 (73%) vs 10/10 (100%) | 14/16 (87.5%) vs 15/17 (88%) |
| Current study | Euroflow |
10−6: 76% 10−5: 24% |
92 |
92 (100%) |
35 (38%) |
CR confirmed at least 6 months after end of therapy |
MRD pos: 13 months; MRD neg: 12 months |
50 (54%) |
23 months |
26% vs 2% |
18/19 (95%) vs 20/28 (71%) |
23/25 (92%) vs 15/26 (57%) |
ASCT autologous stem cell transplantation, BM bone marrow, CR complete response (hematologic), MFC multiparametric flow cytometry, MRD minimal residual disease, NA not available, NGF next-generation flow, NEG negative, POS positive, PFS progression-free survival, pts. patients, VGPR very good partial response.
aMRD negativity in 16 out of 22 patients in VGPR.
bMRD negativity in 2 patients with less than VGPR and in 11 out of 22 patients in VGPR.