Comparison of ALI group among MM patients
Among the 269 MM patients included in this study, there were 166 males (61.7%) and 103 females (38.3%), and the median age of them was 64 (30 - 88) years. The median ALI of the 269 patients was 43.596 (2.7 - 324.6). We treated ALI as independent variable. According to the sensitivity and specificity in the ROC curve, Youden index was calculated. and the cut-off value for ALI was defined as the one with corresponding largest Youden index. The ALI, which is a continuous variable, was used as the test variable, and diagnosed with MM was used as the state variable. The cut-off value of ALI was 45.8 (95% CI 0.63 - 0.74), for which the area under the ROC curve was 0.685, and the sensitivity and specificity was 82.3% and 53.8%, respectively (Figure 1). The patients were further divided into the low ALI group (ALI ≤ 45.8, n =147) and high ALI group (ALI > 45.8, n=122). On comparing with the high ALI group, more patients in the low ALI group were with higher β2 microglobulin levels (P=0.038) and later ISS stages (P=0.039). The other clinical characteristics of the patients were not significantly different between the two groups (P > 0.05) (Supplementary Table 1).
Chemotherapy responses in the high and low ALI groups
Among the 269 MM patients, 231 (85.87%) received bortezomib-based chemotherapy, and 38 (14.13%) received conventional chemotherapy. The treatment regime did not show any significant different between the high and low ALI groups. The rate of ≥ VGPR and ≥ PR were 53.3% and 71.8% in the 269 patients after 4 courses treatments. In detail, the rate of ≥ VGPR and ≥ PR were 56% and 68.5% in the low ALI group, and 50.4% and 75.4% in the high ALI group, respectively, but it does not show statistically difference between the two groups (Supplementary Table 1).
Association between ALI and cytogenetics of MM patients
Among the 269 patients, 144 received FISH examination. The results of the FISH examination showed that patients with low ALI at admission were with higher risk of carrying positive TP53 mutation, compared to the ones with high ALI (P = 0.032). However, IgH, RB-1, and 1q were not significantly different between the two groups (Table 1).
Survival analysis
During the follow up, 198 of the 269 MM patients survived, while the other 71 died. The median survival time of the MM patients was 18.3 months. In detail, 98 and 24 patients in the high ALI group survived and died, respectively, and the median survival time was 19.8 months; while 100 and 47 patients in the low ALI group survived and died, respectively, and the median survival time was 13 months. Survival analysis showed that the OS (log-rank test, P = 0.011) and PFS (log-rank test; P = 0.015) in the low ALI group were significantly lower than in the high ALI group (Figure 2). Univariate COX regression analysis showed that ALI (P = 0.011), extramedullary infiltration (P <0.001), age (P = 0.047), PLT (P = 0.002), LDH (P = 0.002), TP53 (P = 0.003), complex chromosome karyotype (P = 0.001), and bone destruction (P = 0.026) were risk factors influencing the OS of MM patients. Multivariate Cox regression analysis showed that ALI (P = 0.007), extramedullary infiltration (P = 0.001), TP53 (P = 0.020), PLT (P = 0.005), and bone destruction (P = 0.024) were independent risk factors influencing the OS of MM patients (Table 2). In addition, univariate COX regression analysis showed that ALI (P = 0.005), extramedullary infiltration (P = 0.004), age (P = 0.040), Hb (P = 0.024), PLT (P = 0.001), LDH (P = 0.024), TP53 (P < 0.001), and complex chromosome karyotype (P = 0.026) were the risk factors influencing the PFS of MM patients. Multivariate Cox analysis showed that ALI (P = 0.005), extramedullary infiltration (P = 0.004), TP53 (P < 0.001), PLT (P = 0.017), and complex chromosome karyotype (P = 0.010) were the independent risk factors influencing the PFS of MM patients (Table 3).
Association of ALI change with OS and PFS
The patients were divided into 4 subgroups as follows according to the ALI changes after 4 courses treatments, comparing with the pre-treatment ALI: 1) subgroup 1: low pre- and post- treatment ALI (n = 111, 42.7%); 2) subgroup 2: low pre-treatment but high post-treatment ALI (n = 28, 10.8%); 3) subgroup 3: high pre-treatment but low post-treatment ALI (n = 67, 25.8%); and 4) subgroup 4:high pre- and post- treatment ALI (n = 54, 20.8%). The treatment responses in different subgroups were assessed, and the results showed that the overall response rate (ORR) was significantly higher in the subgroup 2 than subgroups 1 and 3 (subgroup 1 vs. subgroup 2 vs. subgroup 3: 68.5% vs. 96.4% vs. 71.6%, P = 0.016), but was not significantly different between other subgroups. The very good partial response rate (VGPR) was significantly higher in the subgroup 2 than subgroups 1, 3, and 4 (subgroup 1 vs. subgroup 2 vs. subgroup 3 vs. subgroup 4: 51.4% vs. 78.6% vs. 46.3% vs. 53.7%, P < 0.001), but was not significantly different between other subgroups (Table 4). Based on the Chi square data, a significant connectivity between subgroups 1 and 2 (P = 0.002), subgroups 1 and 4 (P = 0.001), and subgroups 2 and 3 (P = 0.017) with respect to overall survival was observed (Table 5). With respect to PFS, a significant connectivity between subgroups 1 and 2 (P = 0.002), subgroups 1 and 4 (P = 0.003), and subgroups 2 and 3 (P = 0.042) with respect to overall survival was observed (Table 5).
Analysis of the prognosis in different subgroups showed that the median OS in the high pre- and post- treatment ALI subgroup (group 4) was the highest (64.67 months, P < 0.0125), while the prognosis of patients were poorer in the low pre- and post- treatment ALI subgroup (median OS: 32.23 months, P < 0.0125), as well as high in the pre-treatment but low in the post-treatment ALI subgroup (median OS: 33.31 months, P < 0.0125). The median OS in the patients that the post-treatment ALI increased was better than the ones with high pre-treatment but low post-treatment ALI (subgroup 2 vs. subgroup 3: 56.78 vs. 33.31 months, P < 0.0125). In addition, for the patients with low pre-operative ALI, the median OS in the ones that the ALI increased after 4 courses treatments (subgroup 2) was better (subgroup 1 vs. subgroup 2: 32.23 vs. 56.78 months, P < 0.0125) (Figure 3).