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The diagnostic evaluation of myeloproliferative neoplasms (MPNs) depends on the close correlation between clinical features, morphologic assessment of a trephine bone marrow biopsy, and molecular markers. Typically, MPNs have driver mutations in JAK2, CALR, or MPL, as well as mutations in genes related to epigenetic regulation, RNA splicing, and signaling. Mutations in these genes are a hallmark of diagnostic, prognostic, and therapeutic assessment in patients with MPNs. In line with the World Health Organization classification, all myeloproliferative disorders require molecular characterization to support diagnoses or confirm entities defined by underlying molecular abnormalities. A structured molecular analysis workflow is essential for a rapid and cost-effective diagnosis of MPN. The purpose of this review is to explore the role of molecular diagnostics in the assessment of BCR::ABL1-negative MPNs.

The role of next-generation sequencing (NGS) in identifying mutations in the driver, epigenetic regulator, RNA splicing, and signaling pathway genes in myeloproliferative neoplasms (MPNs) has contributed substantially to our understanding of the disease pathogenesis as well as disease evolution. NGS aids in determining the clonal nature of the disease in a subset of these disorders where mutations in the driver genes are not detected. There is a paucity of real-world data on the utility of this test in the characterization of triple-negative myeloproliferative neoplasms (TN-MPN). In this study, 46 samples of TN-MPN (essential thrombocythemia (ET) = 17; primary myelofibrosis (PMF) = 23;myeloproliferative neoplasm unclassified (MPN-u) = 6) were screened for markers of clonality using targeted NGS. Among these, 25 (54.3%) patients had mutations that would help determine the clonal nature of the disease. Eight of the 17 TN-ET (47%) and 13 of the 23 TN-PMF (56.5%) patients had noncanonical mutations in the driver genes and mutations in the genes involved in epigenetic regulation. Identification of mutations categorized as high molecular markers (HMR) in 2 patients helped classify them as PMF with high risk according to the MIPSS 70 scoring system. A novel mutation in the MPIG6B (C6orf25) gene associated with childhood myelofibrosis was detected in a 14-year-old girl. The presence of clonal hematopoiesis could be confirmed in four of the six MPN-u patients in this cohort. This study demonstrates the utility of NGS in improving the characterization of TN-MPN by establishing clonality and detecting noncanonical mutations in driver genes, thereby aiding in clinical decision-making.

BackgroundFanconi anaemia (FA) is a rare inherited bone marrow failure disease caused by germline pathogenic variants in any of the 22 genes involved in the FA-DNA interstrand crosslink (ICL) repair pathway. Accurate laboratory investigations are required for FA diagnosis for the clinical management of the patients. We performed chromosome breakage analysis (CBA), FANCD2 ubiquitination (FANCD2-Ub) analysis and exome sequencing of 142 Indian patients with FA and evaluated the efficiencies of these methods in FA diagnosis.MethodsWe performed CBA and FANCD2-Ub analysis in the blood cells and fibroblasts of patients with FA. Exome sequencing with improved bioinformatics to detect the single number variants and CNV was carried out for all the patients. Functional validation of the variants with unknown significance was done by lentiviral complementation assay.ResultsOur study showed that FANCD2-Ub analysis and CBA on peripheral blood cells could diagnose 97% and 91.5% of FA cases, respectively. Exome sequencing identified the FA genotypes consisting of 45 novel variants in 95.7% of the patients with FA.FANCA(60.2%),FANCL(19.8%) andFANCG(11.7%) were the most frequently mutated genes in the Indian population. AFANCLfounder mutation c.1092G>A; p.K364=was identified at a very high frequency (~19%) in our patients.ConclusionWe performed a comprehensive analysis of the cellular and molecular tests for the accurate diagnosis of FA. A new algorithm for rapid and cost-effective molecular diagnosis for~90% of FA cases has been established.

The standard of care for patients with acute promyelocytic leukemia (APL) relapsing after frontline treatment with arsenic trioxide (ATO) based regimens remains to be defined. Available data on response and survival outcomes in patients who had received ATO as part of upfront therapy suggests that there is a high incidence of resistance to ATO and ATRA resulting in inferior response and survival (Zhu HH et al. N Engl J Med. 2014). We present our experience on management of relapse in APL patients treated with frontline ATO based therapy. Data on all consecutive patients with relapsed APL diagnosed and treated in the Depatment of Haematology, Christian Medical College, Vellore, from January, 1998-December, 2015 were included in this retrospective analysis. One hundred and four (29%) out of the total 358 APL patients diagnosed during the study period had relapsed. Out of these 73 (70%) patients received upfront ATO based therapy. Six out of 73 refused treatment and got discharged at request following the diagnosis of relapse, the remaining 67 (91.8%) were included in the analysis. Median age of patients was 28 years (range: 4-54), 44 (65.7%) were males. Median time to relapse from initial diagnosis was 19.6 months (range: 6 - 128). Relapses were isolated molecular in one, isolated CNS in 6 [9%], bone marrow + CNS in 13 [19.4%] and medullary only in 47 [70.1%] patients. All 67 patients received ATO based therapy (ATO ± ATRA +/- Anthracycline/Bortezomib) as re-induction. 63/67 (94%) achieved molecular remission post re-induction, while 3 (4.5%) died during re-induction and one discontinued treatment. An autologous SCT was offered to all patients who achieved molecular remission, however only a proportion of cases opted for SCT due to financial constraints. Those that did not opt for an autologous SCT were given ATO+ATRA maintenance therapy. 35/63 (55.6%) opted for autologous SCT while 28 (44.4%) continued on maintenance therapy alone. Median time to autologous SCT from relapse was 5.8 months (range: 2 - 32). There were no treatment related deaths following autologous SCT. At a median follow up of 46 months (range: 1-224), the 5 year estimate of OS and EFS (Fig 1) of the whole cohort (n=67) was 73.6% ± 5.7% and 67% ± 6.1%. The 5 year estimate of OS and EFS (Fig 2) of those who received autologous SCT vs those who were on chemotherapy were 90.3% ±5.3 vs 58.6±10.4 %, (P=0.004) and 87.1% ±6.0% vs. 47.7% ±10.3%, (P=0.001) respectively. In unadjusted analysis, those who received chemotherapy as post relapse consolidation had 5.73 (95%CI: 1.86 - 17.65) times risk of relapse as compared to those who received autologous SCT, which was statically significant (P=0.002). In the adjusted analysis (Table 1) those who received chemotherapy the risk of relapse was 7.6 (95%CI: 1.98 - 28.87) times compared to those who received autologous SCT, which was statically significant (P=0.003) after adjusting for age, total WBC at relapse and duration of CR1. Remission induction with ATO based regimens followed by an autologous SCT in patients with relapsed APL who were treated with frontline ATO based regimens is associated with excellent long term survival and should be considered the standard of care even in this setting. Disclosures No relevant conflicts of interest to declare.