Unrelated hematopoietic stem cell transplantation for familial platelet disorder/acute myeloid leukemia with germline RUNX1 mutations.

Germline mutations in RUNX1 result in rare autosomal-dominant familial platelet disorder with predisposition to acute myeloid leukemia (FPD/AML). As genetic analysis is becoming increasingly prevalent, the diagnosis rate of FPD/AML is expected to increase. In this report, we present two pedigrees, one diagnosed molecularly and another highly suspected to be FPD/AML, whose members both received allogeneic hematopoietic stem cell transplantation (HSCT). Both pedigrees had a family history of thrombocytopenia, platelet dysfunction, and hematological malignancies. One family inherited a frameshift mutation (p.P240fs) of RUNX1, a known pathogenic variant. Another family inherited a point mutation (p.G168R) in the runt-homology domain, the clinical significance of which is uncertain at this point. As this mutation was completely absent from all population databases and had a relatively high REVEL score of 0.947, we thought that it would be dangerous to ignore its possible pathogenicity. Consequently, we avoided choosing HSCT donors from relatives of both families and performed HSCT from unrelated donors. In conclusion, our experience with two families of FPD/AML highlights the importance of searching for gene mutations associated with germline predisposition and indicates the necessity of developing a donor coordination system for FPD/AML patients, as well as a support system for families.

Successful azacitidine therapy for myelodysplastic syndrome associated with VEXAS syndrome.

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is caused by UBA1 somatic mutations and is characterized by late-onset systemic autoimmune inflammation and blood abnormalities such as cytopenia, vacuolation of myeloid/erythroblastic cells, and myelodysplastic syndrome (MDS). It is often resistant to immunosuppressive therapy, and no treatment strategy has been established. A 65-year-old man presented with palpable erythema, fever, macrocytic anemia, and arthralgia. He was subsequently diagnosed with MDS complicated by Sweet's disease. Treatment with azacitidine was initiated due to suspected skin invasion by MDS cells and resistance of the skin rash to steroid therapy. Next-generation sequencing of bone marrow samples prior to treatment initiation revealed the presence of UBA1 p.M41L (VAF 0.38) and DNMT3A p.L605fs mutations (VAF 0.184). Based on the findings of systemic inflammation, a diagnosis of VEXAS syndrome was made. The fever and skin rash improved with azacitidine therapy. In conclusion, somatic mutations in UBA1 should be explored in patients with MDS exhibiting systemic autoimmune inflammation. Furthermore, azacitidine may be a good treatment option for systemic autoinflammation in MDS associated with VEXAS syndrome.

Dual inhibition of the mTORC1 and mTORC2 signaling pathways is a promising therapeutic target for adult T-cell leukemia.

Adult T-cell leukemia (ATL) has a poor prognosis as a result of severe immunosuppression and rapid tumor progression with resistance to conventional chemotherapy. Recent integrated-genome analysis has revealed mutations in many genes involved in the T-cell signaling pathway, suggesting that the aberration of this pathway is an important factor in ATL pathogenesis and ATL-cell proliferation. We screened a siRNA library to examine signaling-pathway functionality and found that the PI3K/Akt/mTOR pathway is critical to ATL-cell proliferation. We therefore investigated the effect of mammalian target of rapamycin (mTOR) inhibitors, including the dual inhibitors PP242 and AZD8055 and the mTORC1 inhibitors rapamycin and everolimus, on human T-cell leukemia virus type 1 (HTLV-1)-infected-cell and ATL-cell lines. Both dual inhibitors inhibited the proliferation of all tested cell lines by inducing G1-phase cell-cycle arrest and subsequent cell apoptosis, whereas the effects of the 2 mTORC1 inhibitors were limited, as they did not induce cell apoptosis. In the ATL-cell lines and in the primary ATL samples, both dual inhibitors inhibited phosphorylation of AKT at serine-473, a target of mTORC2, as well as that of S6K, whereas the mTORC1 inhibitors only inhibited mTORC1. Furthermore, AZD8055 more significantly inhibited the in vivo growth of the ATL-cell xenografts than did everolimus. These results indicate that the PI3K/mTOR pathway is critical to ATL-cell proliferation and might thus be a new therapeutic target in ATL.

HTLV-1 bZIP factor suppresses TDP1 expression through inhibition of NRF-1 in adult T-cell leukemia.

Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). We recently reported that abacavir, an anti-HIV-1 drug, potently and selectively kills ATL cells. This effect was attributed to the reduced expression of tyrosyl-DNA-phosphodiesterase 1 (TDP1), a DNA repair enzyme, in ATL cells. However, the molecular mechanism underlying the downregulation of TDP1 in ATL cells remains elusive. Here we identified the core promoter of the TDP1 gene, which contains a conserved nuclear respiratory factor 1 (NRF-1) binding site. Overexpression of NRF-1 increased TDP1-promoter activity, whereas the introduction of dominant-negative NRF-1 repressed such activity. Overexpression of NRF-1 also upregulated endogenous TDP-1 expression, while introduction of shNRF-1 suppressed TDP1 in Jurkat T cells, making them susceptible to abacavir. These results indicate that NRF-1 is a positive transcriptional regulator of TDP1-gene expression. Importantly, we revealed that HTLV-1 bZIP factor (HBZ) protein which is expressed in all ATL cases physically interacts with NRF-1 and inhibits the DNA-binding ability of NRF-1. Taken together, HBZ suppresses TDP1 expression by inhibiting NRF-1 function in ATL cells. The HBZ/NRF-1/TDP1 axis provides new therapeutic targets against ATL and might explain genomic instability leading to the pathogenesis of ATL.

Successful treatment with intravesical cidofovir for virus-associated hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation: A case report and a review of the literature.

Virus-associated hemorrhagic cystitis (VAHC) is a formidable complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The standard management of severe VAHC after allo-HSCT has not been established. Intravenous administration of cidofovir (CDV), an acyclic nucleoside analogue with broad-spectrum activity against DNA viruses, has been reported to be effective for VAHC, but it can cause severe renal toxicity. Here we report four cases who achieved clinical responses with intravesical instillation of CDV for severe VAHC after allo-HSCT. Median age was 57 years (40-63), and all were male. The underlying diseases were hematological malignancies. Three had received bone marrow transplantation, and one received cord blood transplantation twice. Conditioning regimen was myeloablative for one, and reduced-intensity for three. The viral types were BK virus and/or adenovirus. Two patients had received CDV intravenously prior to the intravesical therapy. A dose of intravesical CDV was 2-5 mg/kg. In all cases, symptoms of cystitis improved dramatically within a few days without showing any systemic adverse effects. The virological response was observed in two cases. This local therapy was effective even in the cases refractory to the intravenous CDV and a case with severe renal failure. Along with the review of literature, we propose that the intravesical instillation of CDV can be a therapeutic option for severe VAHC after allo-HSCT.