This study reports two cases of dasatinib-associated lymphadenopathy (DAL). Case 1 involved a 58-year-old man diagnosed with chronic myelogenous leukemia (CML). After 13 months of starting on dasatinib treatment, a molecular response (MR) 4.5 was achieved. Due to the loss of MMR, dasatinib was discontinued at 39 months but restarted at 42 months. Right cervical lymphadenopathy appeared 51 months after starting the treatment. DAL was diagnosed based on the findings of a cervical lymph node biopsy. After dasatinib was switched to ponatinib, the lymphadenopathy disappeared without recurrence. In case 2, a 54-year-old man was diagnosed with CML. He was started on dasatinib and MR 4.5 was achieved after 6 months. Left cervical lymph node adenopathy appeared 21 months later, and a diagnosis of DAL was made based on the findings of a cervical lymph node biopsy. After discontinuation of dasatinib, cervical lymph node adenopathy disappeared without recurrence. The possibility of DAL should be considered if lymphadenopathy is observed during dasatinib treatment.

Acquired factor V deficiency is a rare disease that presents with various bleeding symptoms because of the acquired production of factor V inhibitors and decrease in factor V activity. We have experienced five cases of acquired factor V deficiency diagnosed on the basis of abnormalities in coagulation tests in the last 10 years. All five patients were older men, of whom one had no bleeding symptoms, and three had a history of renal failure and malignant tumors. In the cross-mixing test, two of three cases demonstrated an inhibitor pattern, but one case showed a deficient pattern. In all cases, steroid treatment improved factor V activity as well as prothrombin time and activated partial thromboplastin time. However, patients with intracranial hemorrhage had a poor prognosis. Although this disease is rare, careful management is necessary, especially in the absence of bleeding symptoms and where cross-mixing test does not show an inhibitor pattern.

A 62-year-old female was presented to the hospital of the current study for pancytopenia and was diagnosed with severe aplastic anemia. She was treated with a combination therapy of antithymocyte globulin, cyclosporine A, and eltrombopag. The patient also presented with febrile neutropenia after commencement of the treatment and did not respond to the various antibiotics and antifungal agents. Echocardiography showed a giant vegetation attached to the tricuspid valve on Day 78 of the immunosuppressive therapy, and the tricuspid valve replacement was performed. The vegetation was formed by Cunninghamella bertholletiae, a mucor type, and was treated with high-dose liposomal amphotericin B (L-AMB), which was terminated after six weeks due to decreased renal function. In addition, mucormycosis was controlled by posttreatment with posaconazole (PSCZ). This is a rare case of mucormycosis that developed into a giant vegetation during the immunosuppressive therapy for aplastic anemia. It was believed to be a valuable case to consider in future mucormycosis treatment, including the success of the treatment by switching from L-AMB to PSCZ.

A 22-year-old man with a history of mediastinal germ cell tumor, which was diagnosed at age 20 and remained disease-free after chemotherapy, was diagnosed with acute myeloid leukemia (AML) M2 in January 2020. Karyotype analysis of bone marrow (BM) specimen at diagnosis detected 47,XXY, inv (16) in all cells. Following induction treatment, he achieved complete remission with a remarkable decrease in the minimal residual disease marker. Although considered related to therapy, the AML had a prognostically favorable karyotype, and the initial treatment response was very good. He had no human leukocyte antigen-matched sibling donor candidate. Thus, allogeneic hematopoietic stem cell transplantation was not scheduled at the first complete remission. After three cycles of consolidation therapy, he remained disease-free for over one year. Karyotype analysis of BM during remission revealed that all analyzed cells harbored 47,XXY, and Klinefelter syndrome (KS) was diagnosed. Although the patient experienced an adjustment disorder on KS diagnosis, he had overcome the difficulty with the assistance of psycho-oncologists, clinical psychologists, and genetic counselors. Herein, we report this rare case of KS that manifested after AML diagnosis following mediastinal germ cell tumor treatment.

An 83-year-old man with chronic obstructive pulmonary disease, hypothyroidism, and osteoporosis developed neutropenia. He was diagnosed with agranulocytosis based on suppression and maturation arrest of myeloid series in the bone marrow. All of his prescriptions were stopped, and he was given granulocyte colony-stimulating factor because he was suspected to have drug-induced agranulocytosis. His neutropenia improved for a while, but it returned a month later. Serum soluble interleukin-2 receptor levels were elevated in his blood, and an abdominal computed tomography scan revealed splenomegaly with no lymph node enlargement. However, due to his old age, a splenectomy was not performed, and no definitive diagnosis was given. He received rituximab therapy after being considered for splenic marginal zone lymphoma or autoimmune neutropenia. His splenomegaly improved, but his neutropenia did not. He was then given ciclosporin, which resulted in a complete response. Because of the presence of large granular lymphocytes in the peripheral blood and bone marrow but no T-cell receptor gene rearrangement, the case was defined as chronic idiopathic neutropenia with activated T cells.

A 68-year-old male patient with lung adenocarcinoma, who was treated with chemotherapy and immune checkpoint inhibitors (ICIs), developed lymphadenopathy during treatment. His para-aortic lymph nodes increased to 2.0 cm in diameter. Both inguinal lymph nodes were 1.5 cm in diameter, and multiple hepatic masses appeared. After the ICI readministration, both inguinal lymph nodes increased to 2.0 cm in diameter, but the para-aortic lymph nodes and hepatic masses remained. Angioimmunoblastic T-cell lymphoma (AITL) diagnosis was established after the right inguinal lymph node biopsy, which was accompanied by an infiltration of Epstein-Barr virus (EBV)-encoded small ribonucleic acid-positive B-cells. After the ICI discontinuation, the inguinal lymph nodes decreased to 1.5 cm in diameter, but the para-aortic lymph nodes remained, and hepatic masses increased. Hepatic lesions were possibly lung cancer metastasis. The ICI administration and EBV reactivation were potentially associated with AITL development in the present case. The natural shrinkage of lymphoma after the ICI cessation implied the immunological mechanism like that of the methotrexate-related lymphoproliferative disease.

FMS-like tyrosine kinase 3 (FLT3) inhibitors improve the prognosis of FLT3-internal tandem duplication (ITD)-positive acute myeloid leukemia (AML). Case 1 is a 47-year-old male patient who presented with a white blood cell count (WBC) of 95,700/ml with 94% blast accompanied by cuplike nuclei, lactate dehydrogenase (LDH) of 2,434 IU/l, fibrin degradation products (FDP) of 476 mg/ml, and a bone marrow examination that revealed blastic marrow with chromosome 46, XY, positive FLT3-ITD, and positive nucleophosmin 1 (NPM1) mutation type A. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and human leukocyte antigen-DR isotype (HLA-DR). The patient had no response to idarubicin combined cytarabine; however, qiuzartinib administration resulted in the first complete remission. Case 2 is a 71-year-old female patient, who presented with 94,900/ml of WBC with a 91% blast accompanied with cup-like nuclei, LDH of 19,03 IU/l, FDP of 112 mg/ml, and a peripheral blood examination that revealed chromosome 46, XX, positive FLT3-ITD, and positive NPM1 mutation type B. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and HLA-DR. She had a partial response to venetoclax combined with azacytidine, and qiuzartinib administration resulted in the first complete remission. Both cases were CD34- and HLA-DR-negative with disseminated intravascular coagulation mimicking acute promyelocytic leukemia (APL). Additionally, recognizing the cuplike blasts is useful to differentiate FLT3 mutant AML from APL for the proper use of FLT3 inhibitors.

A 62-year-old female patient was diagnosed with Waldenstrom’s macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) 8 years ago, which was resolved with rituximab (R) monotherapy. Five years ago, she experienced numbness of the lower limbs, followed by diminished lower limb muscle strength and hearing disturbance. PET-CT scans showed accumulations along the peripheral nerves of the upper and lower limbs together with clonal B lymphocytes in the cerebrospinal fluid, thus a diagnosis of relapse with Bing-Neel syndrome (BNS). After a temporal remission by high-dose cytarabine or bendamustine plus R regimens as salvage treatments, WM/LPL recurred for the third time accompanied by gait disturbances due to muscle weakness and urinary retention. Thus, tirabrultinib was started as a subsequent therapy, which significantly improved the neurological condition together with abnormal findings of magnetic resonance imaging or cerebrospinal fluids. This case is valuable since few relapsed BNS was reported in the literature with successful tirabrutinib treatment.

Although several types of chimeric antigen receptor (CAR)-modified T cells (CAR-T cells) targeting myeloid antigens have been developed for acute myeloid leukemia (AML) globally, significant clinical benefits have not yet been reported. Furthermore, CAR-T cells targeting juvenile myelomonocytic leukemia (JMML) have not yet been developed. All JMML cells and 63-83% of AML cells express granulocyte macrophage-colony stimulating factor (GM-CSF) receptor (GMR, CD116/CD131 complex). Therefore, we created ligand-based CAR-T cells targeting GMR using the piggyBac transposon system. We further redesigned the CAR construct by optimizing the affinity of the antigen-binding region and length of the spacer region. The GMR CAR-T cells with a mutated GM-CSF at residue 21 (E21K) and a G4S spacer showed superior antitumor effects in the human AML-xenograft model. Safety tests revealed that the toxicity of GMR CAR-T cells was restricted to normal monocytes. Based on the promising results of the nonclinical study, we started a first-in-human clinical trial of GMR CAR-T cells in patients with CD116-positive AML and JMML in 2021.

The efficacy of adoptive immunotherapy using CD19-targeting chimeric antigen receptor (CAR)-engineered T cells against B-cell malignancies has already been established in the clinic. However, high economic costs and heterogeneous quality of CAR-T cells derived from individual patients hinder further expansion of their applicability to various cancer types, including solid tumors. Mass CAR-T cell production from healthy donors is a promising approach to overcome these problems, given that allogeneic immunity elicited against donor CAR-T cells by the recipient’s immune system is controlled. CAR-T cells genetically ablated with T-cell receptor and human leukocyte antigen molecules, referred to as universal CAR-T cells, may enable the use of allogeneic T cells for off-the-shelf adoptive cancer immunotherapy. However, several concerns, such as poor persistence of infused CAR-T cells and chromosomal abnormalities due to genome editing, remain to be addressed. Thus, recent clinical trials on universal CAR-T cells are summarized and future perspectives to overcome current challenges are discussed in this review.

Infant acute lymphoblastic leukemia (ALL), which develops in the first year of life, is a rare disease with approximately 20 cases per year in Japan. In particular, KMT2A (MLL) gene rearranged ALL (KMT2A-rALL) has a dismal prognosis, with a 5-year event-free survival rate of <50%. Moreover, acute and late severe toxicities from infants’ intensive treatment remain an issue. Although outcomes of domestic and international clinical trials appear to improve gradually, the problem remains intractable. Therefore, introducing more appropriate risk stratification and less toxic and more effective novel treatment strategies is urgently required to improve the prognosis and long-term survival of infants with ALL. To achieve these goals, establishing new treatment strategies using novel agents through international collaborative studies is warranted in the future.

Tyrosine kinase inhibitor (TKI)-combined chemotherapy has become the standard option in pediatric Philadelphia chromosome-positive acute lymphocytic leukemia (Ph+ALL) treatment. Additionally, hematopoietic cell transplantation (HCT) in the first remission is no longer an absolute indication. However, pediatric Ph+ALL remains refractory leukemia, with a disease-free survival rate of approximately 60% for patients without HCT in the first remission due to treatment-related death or relapse after chemotherapy. Further outcome improvement will require an intensified targeted therapy with second- or third-generation TKIs or less toxic immunotherapies, as well as improved safety, with reduced conventional chemotherapy. Continuous attention to these issues in clinical trials will change pediatric Ph+ALL from intractable to manageable leukemia in the future.

T-cell acute lymphoblastic leukemia (T-ALL) accounted for approximately 10-15% of pediatric ALL and has often been treated within the same framework as B-cell precursor ALL (BCP-ALL). T-ALL has a poorer prognosis than BCP-ALL. However, improvements have been achieved through treatment intensification strategies using dexamethasone, L-asparaginase, and nelarabine, thereby reducing cranial irradiation. Furthermore, T-ALL-specific treatment protocols have been introduced based on these advancements. The JPLSG ALL-T11/JALSG T-ALL-211-U trial in Japan has been conducted from 2011 to 2017 for newly diagnosed patients with T-ALL under the age of 25 years. The trial included minimal residual disease-based treatment stratification and treatment intensification as described above and has shown excellent outcomes. Recently, new therapeutic agents have been actively developed for T-ALL. Thus, targeted therapy development based on new findings is expected in the future.

Over the last 60 years, treatment outcomes for pediatric B cell precursor acute lymphoblastic leukemia have improved dramatically, resulting in long-term survival in approximately 90% of cases. These advancements are the results findings of Biological studies, their acceptance as prognostic factors for treatment responses, including MRD, and the accumulation of clinical trials including many randomized controlled trials. Further improvements in the cure rate and reduction of short-term and long-term complications will be issued in the future. To address such issues, new drugs such as immunotherapy and molecular targeted therapy, as well as more precise stratification, are required, and it is expected that progress will be made by promoting clinical trials in the future.

Acute lymphoblastic leukemia (ALL) in adolescents and young adults (AYA) is a relatively new concept that refers to patients aged 15-39 years with unique pathophysiology and requiring specific clinical care. Many clinical studies have revealed that treatment with the pediatric protocol has better disease-free and overall survival than the adult protocol for AYA-ALL. AYA-ALL survival was significantly improved from 30% with the adult regimen to 60-70% with the pediatric regimen. Two types of strategies are available to adapt pediatric regimens to AYA-ALL, a pediatric-inspired and a fully pediatric regimen. Determining the recommended strategy from these two strategies is difficult at this time. New knowledge of AYA-ALL-specific genetic characteristics provides new strategies for targetable ALL, especially Ph-like ALL. New immunotherapy has been approved for refractory and recurrent ALL; however, treatment results of AYA-ALL were improved by introducing the first line of immunotherapy in BCP-ALL, which may have a poor prognosis such as residual MRD. Pediatric and adult hematologists must work together to improve the prognosis of AYA-ALL.