Baseline patient characteristics
| Characteristics | Low-dose group (n=4) | Medium-dose group (n=13) | High-dose group (n=14) | Total (n=31) |
| Median age, years (range) | 60.5 (54–72) | 64.0 (52–74) | 59.5 (45–71) | 61.0 (45–74) |
| ≥65, n (%) | 2 (50.0) | 6 (46.2) | 4 (28.6) | 12 (38.7) |
| Male sex, n (%) | 2 (50.0) | 7 (53.8) | 8 (57.1) | 17 (54.8) |
| ECOG-PS, n (%) | ||||
| 0 | 3 (75.0) | 5 (38.5) | 11 (78.6) | 19 (61.3) |
| 1 | 1 (25.0) | 8 (61.5) | 3 (21.4) | 12 (38.7) |
| Staging based on the R-ISS, n (%) | ||||
| I | 0 (0.0) | 2 (15.4) | 2 (14.3) | 4 (12.9) |
| II | 4 (100.0) | 9 (69.2) | 8 (57.1) | 21 (67.7) |
| III | 0 (0.0) | 2 (15.4) | 3 (21.4) | 5 (16.2) |
| UK | 0 (0.0) | 0 (0.0) | 1 (7.1) | 1 (3.2) |
| Double-hit or triple-hit MM, n (%) | ||||
| Double-hit | 2 (50.0) | 5 (38.5) | 6 (42.9) | 13 (41.9) |
| Triple-hit | 0 (0.0) | 1 (7.7) | 1 (7.1) | 2 (6.5) |
| High lactate dehydrogenase | 0 (0.0) | 2 (15.4) | 1 (7.1) | 3 (9.7) |
| MM type, n (%) | ||||
| IgA-κ | 0 (0.0) | 1 (7.7) | 0 (0.0) | 1 (3.2) |
| IgA-λ | 0 (0.0) | 2 (15.4) | 2 (14.3) | 4 (12.9) |
| IgD-λ | 0 (0.0) | 0 (0.0) | 1 (7.1) | 1 (3.2) |
| IgG-κ | 2 (50.0) | 2 (15.4) | 4 (28.6) | 8 (25.8) |
| IgG-λ | 0 (0.0) | 5 (38.5) | 2 (14.3) | 7 (22.6) |
| Light chain | 2 (50.0) | 3 (23.1) | 4 (28.6) | 9 (29.0) |
| κ | 1 (25.0) | 2 (15.4) | 2 (14.3) | 5 (16.1) |
| λ | 1 (25.0) | 1 (7.7) | 2 (14.3) | 4 (12.9) |
| Non-secretory | 0 (0.0) | 0 (0.0) | 1 (7.1) | 1 (3.2) |
| Extramedullary MM, n (%) | 0 (0.0) | 1 (7.7) | 2 (14.3) | 3 (9.7) |
| % bone marrow BCMA+plasma cells, median (range) | 0.4912 (0.026–0.4092) | 0.44 (0.0044–0.916) | 0.6921 (0.0587–0.9913) | 0.4912 (0.0044–0.9913) |
| BCMA density, median (range) | 7637 (136–8003) | 1023 (61–2756) | 572.5 (203–4422) | 806 (61–8003) |
| Previous therapeutic regimens, median (range) | 7.0 (5–7) | 4.0 (2–13)* | 4.0 (3–12) | 4.0 (2–13) |
| Immunomodulatory agents and proteasome inhibitors | 4 (100.0) | 13 (100.0) | 14 (100.0) | 31 (100.0) |
| ASCT | 2 (50.0) | 1 (7.7) | 4 (28.6) | 7 (22.6) |
| Anti-CD38 mAb | 0 (0.0) | 3 (23.1) | 4 (28.6) | 7 (22.6) |
| Received bridging therapy, n (%) | 0 (0.0) | 3 (23.1) | 4 (28.6) | 7 (22.6) |
*Two patients received two lines of anti-MM therapy.
ASCT, autologous stem cell transplantation; BCMA, B-cell maturation antigen; double-hit MM, two high-risk genetic abnormalities; ECOG-PS, Eastern Cooperative Oncology Group performance status; mAb, monoclonal antibody; MM, multiple myeloma; R-ISS, Revised International Staging System; triple-hit MM, three or more high-risk genetic abnormalities; UK, unknown.