Structure and signifi cance of cytogenetic abnormalities in patients with multiple myeloma

Abstract

Introduction. Cytogenetic and genomic traits of tumour cells are considered the key mediating factors in multiple myeloma (MM). Selected chromosomal abnormalities are prognostic of therapeutic response and patient survival in MM.Aim — to assess of the diversity and rate of chromosomal abnormalities in MM patients and their association with the disease course.Materials and methods. The study enrolled 134 MM patients with pre-treatment bone marrow FISH assay screening for chromosomal abnormalities: t(11;14), t(4;14), t(14;16), t(14;20), t(6;14), hyperdiploidy, del13q14/-13, del17p13/TP53, amp1q21, t(8q24)/cMYC. The studied criteria at the MM onset were: hemogram, lactate dehydrogenase (LDH) activity, calcium, β2-microglobulin and creatinine concentrations, punctate cytology, bone marrow trephine biopsy and/or soft tissue biopsy histology, bone X-ray, immunochemical variant of MM, disease staging. A median follow-up was 20 months (3.2–77.4).Results. The primary chromosomal abnormality rate was 82.9  %, among them t(14q32)/IGH  — 29.1  %, multiple trisomies — 46.3 % and their combination — 7.5 %. The rates of particular t(14q32)/IGH): t(11;14) — 16.4 %, t(4;14) — 12.7 %, t(14;16) and t(14;20) — 3.7 and 2.2 %, respectively. The secondary chromosomal abnormality rate was 69.4 %, among them del13q14/-13 — 40.3 %, amp1q21 — 39.6 %, t(8q24)/cMYC — 17.2 %, del17p13/TP53 — 12.7 %, del1p32 — 2.2 %. Analyses of the primary–secondary abnormality combinations showed that del13q14/-13 is more frequently combined with t(4;14) and less frequently with trisomies (p < 0.05). Amp1q21 occurs more frequently with t(4;14) and less — with t(11;14) (p<0.05). Patients with t(4;14) more frequently (p < 0.05) had anemia at a hemoglobin level<100 g/L, and the presence of amp1q21 and del17p13/TP53-enhanced serum LDH activity (p < 0.05). Abnormality t(8q24)/cMYC more often co-occurred with higher serum β2-microglobulin concentrations (p < 0.05). A three-year overall survival (OS) in del17p13/TP53-positive patients was 35.5 vs. 71.3 % in the negative (p = 0.002) and 50.8 vs. 67 % — in t(8q24)/cMYC-positive and negative patients, respectively (p = 0.001). Patients without amp1q21, with one, with two or more additional 1q21 copies had a five-year OS 79.4, 67.3 and 20.9 %, respectively (p = 0.0016), and a two-year progression-free survival (PFS) 83, 50 and 0 %, respectively (p = 0.005).Conclusion. We establish a negative impact of del17p13/TP53 and t(8q24)/cMYC on patients’ OS in MM, as well as unfavourable effect of amp1q21 on OS and PFS in the presence of two or more additional copies of 1q21 loci.