Clinical utility of 7-probe FISH panel in multiple myeloma in a resource-constrained setting: A retrospective and prospective observational study

Abstract

ABSTRACT Background: A 7-probe fluorescence in situ hybridization (FISH) panel identifying abnormalities such as immunoglobulin heavy chain (IGH) rearrangement, deletion 17p (TP53 – tumor protein 53), hyperdiploidy, and amplification of 1q, t(11;14), t(14;16), and t(4;14) aids in diagnosis and treatment planning for patients with multiple myeloma, particularly for high-risk patients and short-survival rates. Objectives: The primary objective of the study was to stratify patients with multiple myeloma based on the risk of developing the disease. The secondary objective was to assess the frequency of triple- and double-hit myeloma. Materials and Methods: This retrospective and prospective observational study was conducted in the Department of Cytogenetics, Amrita Institute of Medical Science, Kochi, Kerala, India from January 2020 to September 2022. Bone marrow samples were analyzed using the 7-probe FISH panel and stratification for myeloma and risk-adapted therapy (mSMART) classification for risk stratification. Results: We included 123 samples in the study. Results showed hyperdiploidy as the most common abnormality among newly diagnosed patients (110), with 54.5% (n = 60/110) classified as high-risk and 45.5% (n = 50/110) as standard-risk. Amplification of 1q was the most common abnormality in high-risk, while hyperdiploidy prevailed in standard-risk. Out of the 110 patients, 20.9% (n = 23) patients exhibited double-hit myeloma, and only two out of 110 (1.8%) had triple-hit myeloma. Among relapsed cases (13, 11.8%), all were high-risk, with amplification of 1p1q being the most common abnormality. Out of the 13 relapsed cases, five (38.4%) were double-hit myeloma, and one (7.7%) was triple-hit myeloma. In the remaining 7 (53.8%) cases, either one of the standard risk or high-risk abnormalities or both were observed. Conclusion: The 7-probe FISH panel was found to be a better and more comprehensive tool for risk stratification, molecular classification, and further management of multiple myeloma patients, and it led to improved patient care. Karyotyping, in contrast, did not yield any additional information and thus can be avoided.