Evaluation of chromosomal abnormalities by cIg-FISH and association with proliferative and apoptotic indexes in multiple myeloma

Multiple myeloma in Latin America: A systematic review

The incidence of multiple myeloma (MM) has surged globally, particularly in Latin American countries, and is attributable to an aging population and increased life expectancy. This systematic review analyzes the epidemiology, patient characteristics, and treatment outcomes for MM in selected Latin American countries: Brazil, Mexico, Colombia, Argentina, Chile, Peru, and Uruguay. PubMed and the Latin American and Caribbean Health Sciences Literature (LILACS), conference abstracts (between June 2019 and June 2022), and GLOBOCAN registry (January 2010 to June 2022) were electronically searched. Qualitative analysis employed the Joanna Briggs Institute's critical appraisal tool. Among the 586 screened articles, 26 met the inclusion criteria. The participants' median age ranged from 54 to 67 years. GLOBOCAN data revealed that for MM, Brazil and Uruguay had the highest and lowest incidence, 5-year prevalence, and mortality, respectively. Immunoglobulin G was the most common subtype detected. Stage III was frequently diagnosed. Though many approved drugs are available and bispecific antibodies hold promise as a future therapy, limited access, especially for CAR-T cell-based therapy remains a concern. The incidence of MM is increasing in Latin America. Resource constraints and costs hinder access to novel drugs and regimens. Understanding disease patterns and patient characteristics is vital to improve MM management in these countries.

Genetic aberrations in multiple myeloma characterized by cIg-FISH: a Brazilian context

Genetic abnormalities are critical prognostic factors for patients diagnosed with multiple myeloma (MM). This retrospective, multicenter study aimed to contribute with the genetic and clinical characterization of MM patients in a country with continental dimensions such as Brazil. Genetic abnormalities were assessed by cIg-fluorescent in situ hybridization (cIg-FISH) in a series of 152 MM patients (median age 55 years, 58.5% men). Overall, genetic abnormalities were detected in 52.7% (80/152) of patients. A 14q32 rearrangement was detected in 33.5% (n=51), including t(11;14), t(4;14) and t(14;16) in 18.4, 14.1, and 1% of cases, respectively. del(13q) was identified in 42.7% (n=65) of patients, of whom 49.2% (32/65) presented a concomitant 14q32 rearrangement. del(17p) had a frequency of 5.2% (n=8). del(13q) was associated with high plasma cell burden (≥50%, P=0.02), and del(17p) with advanced ISS stages (P=0.05) and extramedullary disease (P=0.03). t(4;14) was associated with advanced Durie-Salmon stages (P=0.008), renal insufficiency (P=0.01) and was more common in patients over 60 years old. This study reports similar frequencies of genetic abnormalities to most series worldwide, whereas the t(14;16) and del(17p), two high risk factors for newly diagnosed patients, exhibited lower frequencies. Our results expand the knowledge on the molecular features of MM in Brazil, a country where innovative therapies that could overcome a poor prognosis for some genetic abnormalities are not always available.

Validation of interphase fluorescence in situ hybridization (iFISH) for multiple myeloma using CD138 positive cells

Background

Multiple myeloma is a plasma cell neoplasm with acquired genetic abnormalities of clinical and prognostic importance. Multiple myeloma differs from other hematologic malignancies due to a high fraction of low proliferating malignant plasma cells and the paucity of plasma cells in bone marrow aspiration samples, making cytogenetic analysis a challenge. An abnormal karyotype is found in only one-third of patients with multiple myeloma and interphase fluorescence in situ hybridization is the most useful test for studying the chromosomal abnormalities present in almost 90% of cases. However, it is necessary to study the genetic abnormalities in plasma cells after their identification or selection by morphology, immunophenotyping or sorting. Other challenges are the selection of the most informative FISH panel and determining cut-off levels for FISH probes. This study reports the validation of interphase fluorescence in situ hybridization using CD138 positive cells, according to proposed guidelines published by the European Myeloma Network (EMN) in 2012.

Method

Bone marrow samples from patients with multiple myeloma were used to standardize a panel of five probes [1q amplification, 13q14 deletion, 17p deletion, t(4;14), and t(14;16)] in CD138⁺ cells purified by magnetic cell sorting.

Results

This test was validated with a low turnaround time and good reproducibility. Five of six samples showed genetic abnormalities. Monosomy/deletion 13 plus t(4;14) were found in two cases.

Conclusion

This technique together with magnetic cell sorting is effective and can be used in the routine laboratory practice. In addition, magnetic cell sorting provides a pure plasma cell population that allows other molecular and genomic studies.