Concomitant deletion of the short arm (del(1p13.3)) and amplification or gain (1q21) of chromosome 1 by fluorescence in situ hybridization are associated with a poor clinical outcome in multiple myeloma.

Background: Chromosome 1 abnormalities in multiple myeloma (MM) are increasingly recognized as high risk-defining features. The authors report the prognostic value of del(1p13.3) by fluorescence in situ hybridization (FISH) at enrollment in subjects treated on total therapy clinical trials 2-6.

Methods: FISH probes were generated from specific BAC DNA clones for the AHCYL1 gene locus (1p13.3) and the CKS1B locus (1q21).

Results: A total of 1133 patients were included in this analysis. Although del(1p13.3) was detected in 220 (19.4%) patients, 1q21gain or 1q21amp were observed in 300 (26.5%) and 150 (13.2%) patients, respectively. Concomitant del(1p13.3) with 1q21 gain or amp was observed in 65 (5.7%) and 29 (2.5%) patients, respectively. There was enrichment of high-risk features such as International Staging System (ISS) stage 3 disease and gene expression profiling (GEP)70 high risk (HR) in the group with del(1p13.3). Presence of del(1p13.3) confers inferior progression-free survival (PFS) and overall survival (OS). On multivariate analysis, the presence of ISS stage 3 disease, GEP70 HR, 1q21gain, and 1q21amp were independent predictors of PFS or OS.

Conclusions: The PFS and OS of patients with combined abnormalities of del (1p13.3)/1q21gain or amp was significantly worse compared to del(1p13.3) alone and 1q21gain or 1q21 amp alone, which identifies a subset of patients with poor clinical outcomes.