PB2186 IMPACT OF CYTOGENETIC ABNORMALITIES ON RESPONSE IN A COHORT OF INDIAN MULTIPLE MYELOMA PATIENTS–IS 13Q DELETION THE NEW 17P IN DISGUISE?

Abstract

Background:R‐ISS (Revised International Staging System) incorporates cytogenetic abnormalities for risk stratification of multiple myeloma. High‐risk cytogenetic abnormalities in R‐ISS include 17p deletion, t(4;14),t(14;16). Detection of these abnormalities by interphase FISH (Fluorescence in‐situ hybridisation) has become a popular modality owing to its targeted detection ability in non‐mitotic cells.Aims:The aim of this study was to observe the frequency of cytogenetic abnormalities in the Indian setting and their co‐relation with treatment outcomes.MethodsRetrospective single‐centre study conducted at a single tertiary care centre from North India. Multiple myeloma FISH panel comprising of 5 abnormalities ‐ 13q deletion, 17p deletion, t(4;14), t(11;14), t(14;16) were done in all patients with multiple myeloma, either at diagnosis or when they were referred for relapse or progression of disease. Records of patients in the last two years (January 2016 ‐July 2018) were analysed.Results:Over a period of 30months, myeloma FISH panel was done in 49 patients. Of these, abnormalities were detected in 52% (n = 25) patients. 90% patients belonged to ISS stage‐3. FISH panel was done at diagnosis, first relapse and disease progression in 77.5% (n = 38), 7.3% (n = 3) and 19.5% (n = 8), respectively. The most common abnormality was 13q deletion (36.7%). 17p deletion,t(4;14) and t(11;14) were seen in 8.2%(n = 4),4%(n = 2) and 2.4% (n = 1) patients, respectively. Response to treatment could be evaluated in 46 patients which was graded as per IMWG (International Myeloma Working Group) response criteria. The overall response rate (CR/VGPR/PR) of patients in different groups–Normal, 13q deletion, 17p deletion was 79.2%, 50%, 50% respectively. This implied that nearly half of the patients (n = 8) in 13q deletion group did not respond to therapy. Of these, 4 patients (50%) had 13q deletion at baseline. The possible reasons for this may be ‐ detection of 13q deletion in relapsed/refractory patients, concomitant t(4;14) on FISH panel, associated 13q deletion detection on conventional karyotyping and lack of 1q amp detection in our panel which could have let to an unfavourable outcome.Summary/Conclusion:IgH translocations are rare in Indian patients. 13q deletions, akin to the 17p group, are associated with high beta‐2 microglobulin levels (ISS‐3), poor responses to bortezomib based therapy and are seen on disease progression.