Objective:To investigate the relationship between retinoblastoma binding protein 1 (RB1) gene deletion and the prognosis of multiple myeloma (MM) patients, and the possible effect of renal insufficiency on it.Methods:A retrospective cohort study was conducted. The clinical data and follow-up information of MM patients who were treated in the Second Affiliated Hospital of Xuzhou Medical University and the Affiliated Hospital of Xuzhou Medical University from December 2020 to November 2023 were collected. According to the presence of RB1 gene deletion in bone marrow samples detected by fluorescence in situ hybridization (FISH), the patients were divided into the RB1 gene deletion group and the RB1 gene non-deletion group, and the clinicopathological characteristics and hematological index levels were compared between the two groups. Renal insufficiency was determined by renal function assessment indicator serum creatinine (Scr) >177 μmol/L. The Spearman test was used to analyze the relationship between the number of RB1 gene deletion positive cells and levels of Scr, hemoglobin and serum calcium in MM patients. The Kaplan-Meier method was used to analyze progression-free survival (PFS), and the Cox proportional hazards model was used to determine the influencing factors of PFS in all MM patients and RB1 gene deletion and non-deletion MM patients.Results:A total of 75 MM patients were enrolled, of whom 24 (32.0%) had RB1 gene deletion. There were no significant differences in gender, age ≥65 years old, bone destruction and lactate dehydrogenase level between the RB1 gene deletion and non-deletion groups (all P > 0.05). There were significant differences in the distributions of patients in each stage of MM International Staging System (ISS) and revised International Staging System (R-ISS) between the two groups, as well as in hemoglobin, serum calcium, Scr, β 2-microglobulin, serum albumin levels, and the proportion of bone marrow plasma cells (all P < 0.05). The number of RB1 gene deletion positive cells was positively correlated with Scr level ( r = 0.863, P = 0.016), but not with hemoglobin and serum calcium levels (both P > 0.05). The PFS of the RB1 gene non-deletion group was better than that of the RB1 gene deletion group (1-year PFS rate: 83.5% vs. 71.7%, 2-year PFS rate: 56.3% vs. 26.3%), and the difference was statistically significant ( P = 0.012). PFS in the non-renal insufficiency group was better than that in the renal insufficiency group (1-year PFS rate: 85.6% vs. 61.9%, 2-year PFS rate: 58.0% vs. 13.5%), and the difference was statistically significant ( P = 0.001). The PFS of patients without renal insufficiency in both the RB1 gene deletion and non-deletion groups was better than that in patients with renal insufficiency, and the differences were statistically significant (both P < 0.05). Multivariate Cox regression analysis showed that ISS stage Ⅲ was an independent risk factor for poor PFS in MM patients (stage Ⅲ vs. stage Ⅰ, HR = 11.317, 95% CI: 1.220-104.979, P = 0.033). Multivariate Cox regression analysis in RB1 gene deletion and non-deletion groups showed that ISS stage Ⅲ (stage Ⅲ vs. stageⅠ, HR = 4.166, 95% CI: 1.419-12.225, P = 0.009), R-ISS stage Ⅲ (stage Ⅲ vs. stage Ⅰ, HR = 3.800, 95% CI: 1.005-14.367, P = 0.049), serum calcium > 2.52 mmol/L (> 2.52 mmol/L vs. ≤2.52 mmol/L, HR = 2.398, 95% CI: 1.037-5.546, P = 0.041) and renal insufficiency (yes vs. no, HR = 2.363, 95% CI: 1.021-5.472, P = 0.045) were independent risk factors for poor PFS in RB1 gene non-deletion MM patients, and serum calcium >2.52 mmol/L (>2.52 mmol/L vs. ≤ 2.52 mmol/L, HR = 3.673, 95% CI: 1.160-11.627, P = 0.027) and renal insufficiency (yes vs. no, HR = 3.985, 95% CI: 1.220-13.016, P = 0.022) were independent risk factors for poor PFS in RB1 gene deletion MM patients. Conclusions:The PFS of MM patients with RB1 gene deletion is worse than that of patients without RB1 gene deletion, RB1 gene deletion may be related to renal insufficiency in MM patients, and the prognosis of MM patients with RB1 gene deletion and renal insufficiency may be worse.

Objective:To investigate the relationship between retinoblastoma binding protein 1 (RB1) gene deletion and the prognosis of multiple myeloma (MM) patients, and the possible effect of renal insufficiency on it.Methods:A retrospective cohort study was conducted. The clinical data and follow-up information of MM patients who were treated in the Second Affiliated Hospital of Xuzhou Medical University and the Affiliated Hospital of Xuzhou Medical University from December 2020 to November 2023 were collected. According to the presence of RB1 gene deletion in bone marrow samples detected by fluorescence in situ hybridization (FISH), the patients were divided into the RB1 gene deletion group and the RB1 gene non-deletion group, and the clinicopathological characteristics and hematological index levels were compared between the two groups. Renal insufficiency was determined by renal function assessment indicator serum creatinine (Scr) >177 μmol/L. The Spearman test was used to analyze the relationship between the number of RB1 gene deletion positive cells and levels of Scr, hemoglobin and serum calcium in MM patients. The Kaplan-Meier method was used to analyze progression-free survival (PFS), and the Cox proportional hazards model was used to determine the influencing factors of PFS in all MM patients and RB1 gene deletion and non-deletion MM patients.Results:A total of 75 MM patients were enrolled, of whom 24 (32.0%) had RB1 gene deletion. There were no significant differences in gender, age ≥65 years old, bone destruction and lactate dehydrogenase level between the RB1 gene deletion and non-deletion groups (all P > 0.05). There were significant differences in the distributions of patients in each stage of MM International Staging System (ISS) and revised International Staging System (R-ISS) between the two groups, as well as in hemoglobin, serum calcium, Scr, β 2-microglobulin, serum albumin levels, and the proportion of bone marrow plasma cells (all P < 0.05). The number of RB1 gene deletion positive cells was positively correlated with Scr level ( r = 0.863, P = 0.016), but not with hemoglobin and serum calcium levels (both P > 0.05). The PFS of the RB1 gene non-deletion group was better than that of the RB1 gene deletion group (1-year PFS rate: 83.5% vs. 71.7%, 2-year PFS rate: 56.3% vs. 26.3%), and the difference was statistically significant ( P = 0.012). PFS in the non-renal insufficiency group was better than that in the renal insufficiency group (1-year PFS rate: 85.6% vs. 61.9%, 2-year PFS rate: 58.0% vs. 13.5%), and the difference was statistically significant ( P = 0.001). The PFS of patients without renal insufficiency in both the RB1 gene deletion and non-deletion groups was better than that in patients with renal insufficiency, and the differences were statistically significant (both P < 0.05). Multivariate Cox regression analysis showed that ISS stage Ⅲ was an independent risk factor for poor PFS in MM patients (stage Ⅲ vs. stage Ⅰ, HR = 11.317, 95% CI: 1.220-104.979, P = 0.033). Multivariate Cox regression analysis in RB1 gene deletion and non-deletion groups showed that ISS stage Ⅲ (stage Ⅲ vs. stageⅠ, HR = 4.166, 95% CI: 1.419-12.225, P = 0.009), R-ISS stage Ⅲ (stage Ⅲ vs. stage Ⅰ, HR = 3.800, 95% CI: 1.005-14.367, P = 0.049), serum calcium > 2.52 mmol/L (> 2.52 mmol/L vs. ≤2.52 mmol/L, HR = 2.398, 95% CI: 1.037-5.546, P = 0.041) and renal insufficiency (yes vs. no, HR = 2.363, 95% CI: 1.021-5.472, P = 0.045) were independent risk factors for poor PFS in RB1 gene non-deletion MM patients, and serum calcium >2.52 mmol/L (>2.52 mmol/L vs. ≤ 2.52 mmol/L, HR = 3.673, 95% CI: 1.160-11.627, P = 0.027) and renal insufficiency (yes vs. no, HR = 3.985, 95% CI: 1.220-13.016, P = 0.022) were independent risk factors for poor PFS in RB1 gene deletion MM patients. Conclusions:The PFS of MM patients with RB1 gene deletion is worse than that of patients without RB1 gene deletion, RB1 gene deletion may be related to renal insufficiency in MM patients, and the prognosis of MM patients with RB1 gene deletion and renal insufficiency may be worse.