Table 1.

Comparing the clinical features of the groups with low and high PD-L1 expression.

	Low (n = 49)	High (n = 77)	P
Age, years	67 (59.5–72.0)	66 (58.0–72.0)
≥ 70 years	22 (44.9)	28 (36.4)	0.340
Sex
Female	22 (44.9)	31 (40.3)	0.607
ECOG performance status
≥ 2	1 (2.0)	7 (9.1)	0.149
Serum M-protein, g/dL	2.1 (0.5–4.6)	1.9 (0.4–4.0)
≥ 3.0 g/dL	22 (44.9)	32 (41.6)	0.712
BM plasma cells, %	30.5 (16.4–56.5)	38.4 (20.4–70.2)
≥ 60%	7 (8.9)	16 (20.8)	0.358
β2-microglobulin, mg/L	4.1 (3.1–10.2)	5.4 (3.2–8.4)
≥ 5.5 mg/L	18 (36.7)	37 (48.1)	0.212
Albumin, mg/dL	3.4 (2.8–4.0)	3.2 (2.9–3.9)
< 3.5 mg/L	26 (53.1)	45 (58.4)	0.553
LDH, IU/L	402.0 (299.3–485.5)	397.0 (308.5–507.5)
≥ Upper normal range	20 (40.8)	36 (46.8)	0.513
Cytogenetic abnormalities
High risk*	13 (26.5)	25 (32.5)	0.479
ISS
Stage I	9 (18.4)	14 (18.2)	0.396
Stage II	22 (44.9)	26 (33.8)
Stage III	18 (36.7)	37 (48.1)
R-ISS
Stage I	6 (12.2)	8 (10.4)	0.911
Stage II	31 (63.3)	48 (62.3)
Stage III	12 (24.5)	21 (27.3)
mSMART 3.0
Standard	29 (59.2)	42 (54.5)	0.609
High	20 (40.8)	35 (45.5)

Data are shown as number (percentage) or median (interquartile range).

BM bone marrow, ECOG Eastern Cooperative Oncology Group, ISS International Staging System, LDH lactate dehydrogenase, mSMART Mayo Stratification for Myeloma and Risk-adapted Therapy, PD-L1, programmed death-ligand 1, R-ISS Revised International Staging System.

*High-risk cytogenetics were defined as t(4;14), t(14;16), del(17/17p), TP53 deletion, or chromosome 1 abnormalities including gain(1q) and del(1p).