Gains on Chromosome Arm 9q Represent a Novel and Independent Marker of Adverse Prognosis in Multiple Myeloma Patients Receiving Upfront High-Dose Chemotherapy and Autologous Stem Cell Transplantation.

Introduction: Genomic aberrations represent important prognostic markers in many hematological cancers. In multiple myeloma (MM), chromosome 13q and 17p deletions (13q−, 17p−) have emerged as important outcome predictors that indicate a dismal prognosis. Other chromosomal abnormalities have been discussed as prognostic markers in this disease but came not out as independent variables when they were tested in a multivariable fashion. However, the complexity of genomic rearrangements and the clinical heterogeneity seen in malignant plasma cell disorders argue against 13q− and 17p− as the sole genomic change of prognostic relevance. The significance of chromosome arm 1q, 9q, and 11q extra copies - three frequent genomic imbalances in MM - is undetermined.

Material and Methods: 90 patients (pts.) treated with one or two cycles of high-dose chemotherapy (HD-CTX) followed by autologous stem cell transplantation (ASCT) at a single center were analyzed by tri-color FISH and five DNA probes mapping to chromosome bands 1q21, 9q34, 11q25, 13q14, and 17p13. A multivariable analysis (Cox proportional hazards regression model) including genetic and clinical variables was performed.

Results: The most frequent aberrations in the present series were (in order of decreasing prevalence): +1q (n=39/78, 50.0%), +9q (n=38/78, 48.7%), 13q− (n=42/90, 46.6%), and +11q (n=39/85, 45.9%). 17p− was identified in only 3 out of 88 patients (3.4%), while +17p were present in 13 out of 88 patients (14.8%). The median follow-up time was 37 months (m) and the median event free survival (EFS) and overall survival (OS) time from first ASCT of the entire cohort was 26 m and 71 m, respectively. Multivariable analysis including genetic aberrations, ß2-microblobulin, albumin, LDH, Salmon/Durie stage, and age at time of diagnosis revealed +9q and 13q− as the only independent predictors of EFS (p=0.003 and p=0.01, respectively). The mEFS in patients with 13q− was 19.0 m and 20.7 m in patients with +9q. In patients with concurrent +9q and 13q−, mEFS was only 12.2 m. In patients lacking these two abnormalities, mEFS was not reached. OS was not significantly influenced by any genetic or clinical variable in our series, most likely due to effective salvage treatment after relapse.

Conclusions: +9q represents a novel and independent marker of adverse prognosis in MM. A single FISH experiment applying two DNA probes allows easy and rapid assessment of outcome in patients with malignant plasma cell disorders.