Genetic alterations in myeloid sarcoma among acute myeloid leukemia patients: insights from 37 cohort studies and a meta-analysis

Introduction

Variations in mutation rates among acute myeloid leukemia (AML) patients with myeloid sarcoma (MS) underscore the need for a thorough examination. This meta-analysis was conducted to fill the information gap concerning mutation frequencies in AML patients presenting with MS.

Materials and methods

This study included retrospective and prospective cohorts. It examined genetic alterations in AML patients with and without MS across all age groups. The search strategy employed terms such as "acute myeloid leukemia," "extramedullary," "granulocytic sarcoma," "myeloid sarcoma," and "leukemic cutis" in the EMBASE, MEDLINE, and Scopus databases. Excluded from the study were reviews, case reports, and case series with fewer than 10 cases. Statistical analyses were performed with Review Manager 5.4 software.

Results

The primary analysis incorporated data from 37 cohorts involving 5646 diagnosed AML patients and revealed a 17.42% incidence of MS. The most prevalent mutation among AML patients with MS was FLT3-ITD, with a pooled prevalence of 17.50% (95% CI 12.60% to 22.50%; I2 82.48%). The dominant fusion gene was RUNX1::RUNX1T1, displaying a pooled prevalence of 28.10% (95% CI 15.10% to 41.20%; I2 96.39%). In comparison, no significant intergroup differences were observed for NPM1, FLT3-ITD, KIT, and IDH2 mutations. Interestingly, the CEBPA mutation exhibited protective effects for MS patients, with an odds ratio of 0.51 (95% CI 0.32 to 0.81; I2 0%). Conversely, the NRAS mutation was associated with an increased risk of MS development, with an odds ratio of 5.07 (95% CI 1.87 to 13.73; I2 0%).

Conclusion

This meta-analysis sheds light on the prevalence of genetic mutations in AML patients with MS, providing insights into the unique characteristics of the mutations and their frequencies. These discoveries are crucial in informing therapeutic and prognostic decisions for individuals with myeloid sarcoma.

ROS1 fusions in cancer: a review

The ROS1 gene belongs to the sevenless subfamily of tyrosine kinase insulin receptor genes. A literature review identified a ROS1 fusion in 2.54% of the patients with lung adenocarcinoma and even higher frequencies in spitzoid neoplasms and inflammatory myofibroblastic tumors. At present, 26 genes were found to fuse with ROS1, some of them already known to fuse with RET and ALK. All the fusion proteins retain the ROS1 kinase domain, but rarely its transmembrane domain. Most of the partners have dimerization domains that are retained in the fusion, presumably leading to constitutive ROS1 tyrosine kinase activation. Some partners have transmembrane domains that are retained or not in the chimeric proteins. Therefore, different ROS1 fusions have distinct subcellular localization, suggesting that they may activate different substrates in vivo.

Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature

Chronic lymphocytic leukemia (CLL) represents the most common hematological malignancy in Western countries, with a highly heterogeneous clinical course and prognosis. Translocations involving the immunoglobulin (IG) genes are regularly identified. From 2000 to 2014, we identified an IG gene translocation in 18 of the 396 patients investigated at diagnosis (4.6%) and in 17 of the 275 analyzed during follow-up (6.2%). A total of 4 patients in whom the IG translocation was identified at follow-up did not carry the translocation at diagnosis. The IG heavy locus (IGH) was involved in 27 translocations (77.1%), the IG κ locus (IGK) in 1 (2.9%) and the IG λ locus (IGL) in 7 (20.0%). The chromosome band partners of the IG translocations were 18q21 in 16 cases (45.7%), 11q13 and 19q13 in 4 cases each (11.4% each), 8q24 in 3 cases (8.6%), 7q21 in 2 cases (5.7%), whereas 6 other bands were involved once (2.9% each). At present, 35 partner chromosomal bands have been described, but the partner gene has solely been identified in 10 translocations. CLL associated with IG gene translocations is characterized by atypical cell morphology, including plasmacytoid characteristics, and the propensity of being enriched in prolymphocytes. The IG heavy chain variable region (IGHV) mutational status varies between translocations, those with unmutated IGHV presumably involving cells at an earlier stage of B-cell lineage. All the partner genes thus far identified are involved in the control of cell proliferation and/or apoptosis. The translocated partner gene becomes transcriptionally deregulated as a consequence of its transposition into the IG locus. With the exception of t(14;18)(q32;q21) and its variants, prognosis appears to be poor for the other translocations. Therefore, searching for translocations involving not only IGH, but also IGL and IGK, by banding and molecular cytogenetics is required. Furthermore, it is important to identify the partner gene to ensure the patients receive the optimal treatment.

Incidence of chromosomal anomalies detected by interphase FISH in chronic lymphoid leukemia

Aims & methods: We used interphase FISH to determine the incidence of chromosomal changes in 638 B-cell chronic lymphocytic leukemia patients. Results: Chromosomal abnormalities were found in some 75% of the patients. Del(13)(q14) was present in 57.3 and 57% of patients at diagnosis and during follow-up, respectively. It was followed by trisomy 12 (19 and 19.8% at diagnosis and during follow-up, respectively), del(11)(q22) (9.1 and 14.3% at diagnosis and during follow-up, respectively) and del(17)(p13) (2.8 and 12.4% at diagnosis and during follow-up, respectively). Discussion & conclusion: Our results correlate with those obtained in 55 studies reported in the literature. Trisomy 12 and del(13)(q14) are present in high proportions at diagnosis and are not enriched during progression, to the contrary of del(11)(q22) and del(17)(p13) that are markers of evolution.