Outcome of Multiple Myeloma with Chromosome 1q Gain and 1p Deletion after Autologous Hematopoietic Stem Cell Transplantation: Propensity Score Matched Analysis

The gain/amplification CKS1B gene at chromosome region 1q21 (1q+) is one of the most common genetic aberrations in multiple myeloma (MM). Amplification of CKS1B is frequently associated with the deletion of the CDKN2C gene at chromosome region 1p32 (1p-), which is also associated with inferior outcomes. In this retrospective study, we evaluated the outcomes of patients with 1q+ and/or 1p- after high-dose therapy and autologous hematopoietic cell transplantation (auto-HCT). From January 2006 to December 2015, 1491 newly diagnosed patients with MM underwent upfront high-dose therapy and auto-HCT at our institution. Of those, 899 had the fluorescent in situ hybridization (FISH) data available. FISH was performed at diagnosis and before the start of induction in 686 (76%) patients and after the initiation of induction therapy in 213 (24%) patients. We identified 100 patients with 1q+ and/or 1p- by FISH from the cohort of 899 patients. A control group (n = 287) with diploid cytogenetics and normal FISH panel was selected from the same cohort. From the above 2 cohorts, using a propensity score matched analysis, we identified matched controls for 85 of the 100 patients with 1q+/1p-. Patients were matched for age at auto-HCT, sex, International Staging System stage, induction regimen, creatinine level, disease status at auto-HCT, conditioning regimen, and maintenance therapy. Sixty-seven (79%), 4 (5%), and 14 (16%) patients had 1q+, 1p-, or both 1q+ and 1p-, respectively. There was no significant difference in induction therapy, preparative regimen, or maintenance therapy between the 1q+/1p- and the control group. The median follow-up time for all patients was 29.2 months (range, 0.29 to 84.96). The cumulative incidence of 100-day nonrelapse mortality was 1.2% and 0% for the 1q+/1p- and the control group, respectively. Forty-two patients (50%) in the 1q+/1p- group achieved complete response compared with 40 patients (47%) in the control group. The estimated 3-year progression-free survival (PFS) and overall survival (OS) rates were 41% and 79% for the 1q+/1p- group and 56% and 86% for the control group. Patients in the 1q+/1p- group were at significantly increased risk of progression or death compared to the control group (hazard ratio [HR], 2.21; confidence interval [CI], 1.18 to 4.16; P = .014). No significant association between OS in the 2 groups was observed. The outcome of the 1q+/1p- alone (with no additional high-risk cytogenetics) and the propensity score matched control groups was also compared. Median PFS for the 1q+/1p- alone subgroup was 26.6 months, compared with 38.8 months for the control group (HR, 1.9; CI, 0.9 to 4.08; P = .09). The median OS had not been reached for the 1q+/1p- alone subgroup and was 81.1 months for the control group (HR, 1.25; CI, 0.3 to 4.6; P= .73). 1q+/1p- abnormalities with amplification of CKS1B and deletion ofCDKN2Cgenes were associated with shorter PFS compared with a propensity score matched group of patients with diploid cytogenetics and normal a FISH panel. The outcomes of 1q+/1p- patients with MM have improved with the use of more effective induction, conditioning, and maintenance therapy compared with historical controls, but we still need more effective therapeutic approaches to fully overcome the negative impact of 1q+/1p-.