Case report: Therapy-related myeloid neoplasms in three pediatric cases with medulloblastoma.

Introduction: Medulloblastoma is the most common malignant brain tumor in children, often requiring intensive multimodal therapy, including chemotherapy with alkylating agents. However, therapy-related complications, such as therapy-related myeloid neoplasms (t-MNs), can arise, particularly in patients with genetic predisposition syndromes. This case report presents three pediatric cases of medulloblastoma with subsequent development of t-MNs, highlighting the potential role of genetic predisposition and the importance of surveillance for hematological abnormalities in long-term survivors. Case presentation: We describe three cases of pediatric medulloblastoma who developed t-MNs after receiving chemotherapy, including alkylating agents. Two of the patients had underlying genetic predisposition syndromes (TP53 pathologic variants). The latency period between initial diagnosis of medulloblastoma and the development of secondary cancer varied among the cases, ranging from 17 to 65 months. The three cases eventually succumbed from secondary malignancy, therapy-related complications and progression of primary disease, respectively. Conclusions: This report highlights the potential association between genetic predisposition syndromes and the development of therapy-related myeloid neoplasms in pediatric medulloblastoma survivors. It underscores the importance of surveillance for hematological abnormalities among such patients.

Successful haploidentical hematopoietic stem cell transplantation (HSCT) and durable engraftment by repeated donor lymphocyte infusions for a Chinese patient with transfusion-dependent hemoglobin (Hb) Hammersmith and massive splenomegaly.

BACKGROUND: Hemoglobin (Hb) Hammersmith is a rare form of unstable ß-chain hemoglobinopathy causing hemolytic anemia. This rare event led to a more serious transfusion-dependent phenotype in a patient. It was successfully cured by haploidentical hematopoietic stem cell transplantation (HSCT). METHODS AND RESULTS: A 9-year-old mainland Chinese male with a history of neonatal unconjugated hyperbilirubinemia was diagnosed to have hemoglobin (Hb) Hammersmith. He required regular blood transfusion but was unable to be transfused to desired parameters for 8 years prior to transplant due to social and geographical reasons. He subsequently developed marrow hyperplasia and progressive splenomegaly (down to umbilicus level), suggestive of extramedullary hematopoiesis. Eventually, the family came to Hong Kong and complied to a more intensive transfusion regimen and preconditioning chemotherapy 3 months prior to transplant. He underwent haploidentical HSCT using paternal TCRαß/CD45RA-depleted graft but suffered from graft rejection, despite splenic irradiation for massive splenomegaly. It was successfully salvaged with second HSCT with unmanipulated graft from the same donor with additional serotherapy and donor lymphocyte infusions. CONCLUSION: Allogenic haploidentical HSCT for hemoglobin Hammersmith is feasible but adequate immunosuppression during conditioning is crucial. Precise adoptive cell therapy can promote durable engraftment.

Distinct mutation spectrum, clinical outcome and therapeutic responses of typical complex/monosomy karyotype acute myeloid leukemia carrying TP53 mutations.

The present study aimed to define a subtype of complex/monosomal karyotype (CK/MK) acute myeloid leukemia (AML) by its distinct clinical features, p53 signaling and responses to p53 targeting agents. Ninety-eight young adults (range: 21-60 years; median: 49 years) with CK/MK AML were studied. They received standard induction, consolidation and allogeneic hematopoietic stem cell transplantation from siblings or matched unrelated donors if available. Chromosomal abnormalities most commonly affected chromosome 5 (30%), 7 (22%) and 17 (21%). Next generation sequencing of a 54-myeloid gene panel were available in 76 patients. Tumor protein 53 (TP53) mutations were most common (49%) and associated with the presence of -5/5q- (P < .001) and -17/17p- (P < .001), but not -7/7q- (P = .370). This "typical" CK/MK AML subtype was associated with significantly lower presenting white cell counts, higher number of karyotypic abnormalities, and inferior leukemia-free and overall survivals, compared with CK/MK AML without the typical features. Blood or bone marrow samples from typical CK/MK AML patients showed defective p53 signaling upon induction by etoposide. In vitro drug sensitivity analysis showed that they were sensitive to APR-246 that targeted mutant p53, but resistant to MDM2 antagonist MI-77301. Novel therapeutic strategies targeting TP53 mutations in CK/MK AML should be developed and tested in clinical trials.

Next-generation sequencing with a 54-gene panel identified unique mutational profile and prognostic markers in Chinese patients with myelofibrosis.

Current prognostication in myelofibrosis (MF) is based on clinicopathological features and mutations in a limited number of driver genes. The impact of other genetic mutations remains unclear. We evaluated for mutations in a myeloid panel of 54 genes using next-generation sequencing. Multivariate Cox regression analysis was used to determine prognostic factors for overall survival (OS) and leukaemia-free survival (LFS), based on mutations of these genes and relevant clinical and haematological features. One hundred and one patients (primary MF, N = 70; secondary MF, N = 31) with a median follow-up of 49 (1-256) months were studied. For the entire cohort, inferior OS was associated with male gender (P = 0.04), age > 65 years (P = 0.04), haemoglobin < 10 g/dL (P = 0.001), CUX1 mutation (P = 0.003) and TP53 mutation (P = 0.049); and inferior LFS was associated with male gender (P = 0.03), haemoglobin < 10 g/dL (P = 0.04) and SRSF2 mutations (P = 0.008). In primary MF, inferior OS was associated with male gender (P = 0.03), haemoglobin < 10 g/dL (P = 0.002), platelet count < 100 × 109/L (P = 0.02), TET2 mutation (P = 0.01) and CUX1 mutation (P = 0.01); and inferior LFS was associated with haemoglobin < 10 g/dL (P = 0.02), platelet count < 100 × 109/L (P = 0.02), TET2 mutations (P = 0.01) and CUX1 mutations (P = 0.04). These results showed that clinical and haematological features and genetic mutations should be considered in MF prognostication.

Pim kinases modulate resistance to FLT3 tyrosine kinase inhibitors in FLT3-ITD acute myeloid leukemia.

Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is frequently detected in acute myeloid leukemia (AML) patients and is associated with a dismal long-term prognosis. FLT3 tyrosine kinase inhibitors provide short-term disease control, but relapse invariably occurs within months. Pim protein kinases are oncogenic FLT3-ITD targets expressed in AML cells. We show that increased Pim kinase expression is found in relapse samples from AML patients treated with FLT3 inhibitors. Ectopic Pim-2 expression induces resistance to FLT3 inhibition in both FLT3-ITD-induced myeloproliferative neoplasm and AML models in mice. Strikingly, we found that Pim kinases govern FLT3-ITD signaling and that their pharmacological or genetic inhibition restores cell sensitivity to FLT3 inhibitors. Finally, dual inhibition of FLT3 and Pim kinases eradicates FLT3-ITD(+) cells including primary AML cells. Concomitant Pim and FLT3 inhibition represents a promising new avenue for AML therapy.

A 3-bp deletion in the HBS1L-MYB intergenic region on chromosome 6q23 is associated with HbF expression.

Fetal hemoglobin (HbF) is regulated as a multigenic trait. By genome-wide association study, we confirmed that HBS1L-MYB intergenic polymorphisms (HMIP) and BCL11A polymorphisms are highly associated with HbF in Chinese ß-thalassemia heterozygotes. In this population, the variance in HbF resulting from the HMIP is 13.5%; that resulting from the BCL11A polymorphism is 6.4%. To identify the functional variant in HMIP, we used 1000 Genomes Project data, single nucleotide polymorphism imputation, comparisons of association results across populations, potential transcription factor binding sites, and analysis of phylogenetic conservation. Based on these studies, a hitherto unreported association between HbF expression and a 3-bp deletion, between 135 460 326 and 135 460 328 bp on chromosome 6q23 was found. This 3-bp deletion is in complete linkage disequilibrium with rs9399137, which is the single nucleotide polymorphism in HMIP most significantly associated with HbF among Chinese, Europeans, and Africans. Chromatin immunoprecipitation assays confirmed erythropoiesis-related transcription factors binding to this region in K562 cells. Based on transient expression of a luciferase reporter plasmid, the DNA fragment encompassing the 3-bp deletion polymorphism has enhancer-like activity that is further augmented by the introduction of the 3-bp deletion. This 3-bp deletion polymorphism is probably the most significant functional motif accounting for HMIP modulation of HbF in all 3 populations.

Pneumococcal native aortic valve endocarditis with mycotic abdominal aortic aneurysm, paraspinal and iliopsoas abscesses and pneumonia revealing a multiple myeloma.

We report a rare case of multiple myeloma presenting with native aortic valve endocarditis with secondary embolic mycotic abdominal aortic aneurysm, contiguous paraspinal and iliopsoas abscesses, and pneumonia due to Streptococcus pneumoniae in a Chinese man. He was treated with aortic valve replacement, endovascular stenting of aneurysm, image-guided drainage of abscesses, and a 6-week course of endocarditic antibiotic therapy followed by chronic suppressive antibiotic therapy. Cases of multiple myeloma presenting with invasive pneumococcal infection were reviewed.

Sickle cell disease caused by heterozygosity for Hb S and novel LCR deletion: Report of two patients.

The b-globin gene LCR is located approximately 6 kb upstream of the embryonic epsilon-globin gene, and is made up of five DNase I hypersensitive sites (HSs), HS 1-5. LCR plays a pivotal role in regulating the expression of downstream epsilon-, (G)gamma-, (A)gamma-, delta-, and beta-globin genes in cis [1]. Deletions removing the LCR and parts of the downstream beta-globin gene cluster in patients have been described [2]. These individuals present with a (gammadeltabeta)0-thalassemia carrier phenotype. We now report two patients with severe sickle cell disease who were compound heterozygous for Hb S mutation and novel LCR deletion. In one case, HS 1-3 were deleted; in the other, HS 1-5 were deleted. In both cases, the b-like globin genes in cis to the LCR deletions were intact. Genotypically, both patients appeared to have sickle cell trait. Coinherited with either LCR deletion, these individuals presented as sickle cell disease patients. The breakpoints of these LCR deletions were defined. These results affirm that HS 2 and 3 are primarily responsible for conferring erythroid specific high-level expression of cis-linked beta-like globin genes. Furthermore, LCR deletions might cause hemolytic disease of newborns.

BCL11A is a major HbF quantitative trait locus in three different populations with beta-hemoglobinopathies.

Increased HbF levels or F-cell (HbF containing erythrocyte) numbers can ameliorate the disease severity of beta-thalassemia major and sickle cell anemia. Recent genome-wide association studies reported that single nucleotide polymorphisms (SNPs) in BCL11A gene on chromosome 2p16.1 were correlated with F-cells among healthy northern Europeans, and HbF among Sardinians with beta-thalassemias. In this study, we showed that SNPs in BCL11A were associated with F-cell numbers in Chinese with beta-thalassemia trait, and with HbF levels in Thais with either beta-thalassemia or HbE trait and in African Americans with sickle cell anemia. Taken together, the data suggest that the functional motifs responsible for modulating F-cells and HbF levels reside within a 3 kb region in the second intron of BCL11A.

Variation and heritability of Hb F and F-cells among beta-thalassemia heterozygotes in Hong Kong.

Enhanced fetal hemoglobin (Hb F) production can partially compensate for the lack of adult hemoglobin (Hb A) in patients with beta-thalassemia major or intermedia, and ameliorate the clinical severity of these diseases. To further elucidate factors governing Hb F levels, we evaluated demographic, clinical, laboratory, and genetic characteristics in 241 unrelated adult beta-thalassemia carriers in Hong Kong. They had wide variations in Hb F and F-cell numbers skewing toward higher levels. Individuals who coinherited the Xmn IT-allele in the (G)gamma-globin gene promoter had higher Hb F and more F-cells compared with those lacking the Xmn I T-allele. However, both groups exhibited a similarly wide spread of Hb F and F-cells. The correlation of Hb F and F-cells corresponded well to both linear and exponential models, suggesting multiple mechanisms for Hb F augmentation. The heritabilities of Hb F and F-cells were calculated in 66 families (111 parents who were beta-thalassemia carriers and 82 asymptomatic offspring) to be 0.7 to 0.9. The Xmn I polymorphism accounted for 9% of the Hb F and 13% of the F-cell heritabilities. These results suggest that these family members are well suited for genome wide association studies that will identify genetic loci regulating Hb F production, and likely novel pharmacological targets for reactivating Hb F production in adults.