Outcome of Multiple Myeloma with Chromosome 1q Gain and 1p Deletion after High-Dose Therapy and Autologous Hematopoietic Stem Cell Transplantation

Background and Aim

The gain/amplification CKS1B gene at chromosome region 1q21 (1q+) is one of the most common genetic aberrations in multiple myeloma (MM). CKS1Bamplification and overexpression contribute to increased p27^Kip1 degradation, cell cycle upregulation and poor outcomes in MM patients. Amplification of CKS1B is frequently associated with the deletion of CDKN2C gene at chromosome region 1p32 (1p-). Deletion of CDKN2C, a tumor suppressor gene, leads to an increased proliferative rate of plasma cells in MM patients and is also associated with inferior outcomes. There are limited data on the impact of 1q+/1p- on the outcomes after high-dose therapy and autologous stem cell transplantation (auto-HCT).

Methods

In this retrospective study, we evaluated outcomes of patients with 1q+ and/or 1p- after high-dose therapy and auto-HCT. From 2007 to 2015, 1365 MM patients underwent high-dose therapy and auto-HCT at our institution. We identified 100 patients with 1q+ and/or 1p- by fluorescent in situ hybridization (FISH) from that cohort. The cut off value used for gain/amplification of a 1q21/CKS1B was 7.9%; gain/amplification of two 1q21/CKS1B was 4.4%; and deletion of a 1p32.3/CDKN2C was 6.8%. A control group (N=287) with diploid cytogenetics and normal FISH panel with no high risk abnormalities was selected from the same cohort. From the above two cohorts, using a 1:1 propensity score-matched analysis without replacement, we were able to identify a matched control for 85 patients with 1q+/1p-.

Results

Baseline characteristics of the 1q+/1p- and control groups are summarized in table 1. 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 two groups. The median follow-up time for all patients was 29.2 months (range: 0.29 -84.96). The cumulative incidence of 100-day nonrelapse mortality was 1.1% and 0% for the 1q+/1p- and the control groups, respectively. Forty-two patients (51%) in the 1q+/1p- group achieved a CR compared to 40 patients (49%) in the control group (P=0.6). VGPR rates in the 1q+/1p- and controls groups were 47% and 53% (P=0.5) respectively. The overall response rate for the 1q+/1p-and controls group was 96% and 100%, respectively (P=0.3). Median PFS for the 1q+/1p- and the controls groups were 26.5 months and 38.8 months, respectively. The estimated 3-year PFS for the 1q+/1p- and the control groups were 41% and 56%, respectively (HR 2.2, CI 1.18-4.16, P=0.01) (Figure 1A). The 3-year OS for the 1q+/1p- and the control groups were 79% and 86%, respectively (HR 1.5, CI 0.61-4.05, P=0.34) (Figure 1B).

Conclusion

1q+/1p- abnormalities with amplification CKS1B and deletion of CDKN2C genes were seen in approximately 7% of MM patients undergoing auto-HCT between 2007 and 2015. They were associated with a shorter PFS when compared to a propensity matched group of patients with diploid cytogenetics and normal FISH panel. Patients with 1q+/1p- may need more aggressive therapeutic approaches.

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