The impact of cytogenetic evolution and acquisition of del(17p) on the prognosis of multiple myeloma patients.

INTRODUCTION Prognosis of patients with newly diagnosed multiple myeloma (MM), a third most common hematological cancer, is dependent on baseline cytogenetics. However, little is known about the prognostic significance of cytogenetic evolution (CE) at the time between the diagnosis and relapse of MM. OBJECTIVES Here, we retrospectively analyzed the prognostic impact of CE detected in a routine interphase fluorescence in situ hybridization (FISH) test in a cohort of patients with MM. PATIENTS AND METHODS Among 650 patients evaluated with the FISH MM panel at our center between 2014 and 2019, we identified 29 individuals with MM who had been tested twice, at the time of diagnosis and relapse. Cytogenetic evolution was defined as the acquisition or loss of at least 1 cytogenetic abnormality at relapse (FISH2) compared with the baseline test result (FISH1). RESULTS Cytogenetic evolution was seen in 14 patients (48%), whereas 15 had stable cytogenetics. Acquired chromosome 17p deletion (del[17p]) was the most common type of CE, found in 7 patients (24%). In univariable analysis, stable cytogenetics predicted longer overall survival (median not reached vs 3.8 years; hazard ratio [HR], 0.15; P = 0.04; median follow-up of 3.1 years) and longer overall survival after FISH2 (median not reached vs 0.8 years; HR, 0.13; P = 0.002; median follow-up of 0.6 years). In multivariable analysis, acquired del(17p) predicted shorter progression-free survival and the overall survival after FISH2 (HR, 9.3 and 18.8; P = 0.005 and P = 0.004, respectively). CONCLUSIONS Presence of CE and, particularly, the acquisition of new del(17p) at relapse, negatively affect the outcome of MM. Therefore, re-evaluation of FISH at MM relapse should be included in routine clinical practice.