Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic stem-cell transplantation is a major post-transplant complication. Although the incidence of fatal CMV disease has improved with the introduction of CMV prophylaxis and pre-emptive therapy, CMV reactivation remains an important factor exacerbating post-transplant non-relapse mortality. The use of anti-viral drugs and/or steroids, effects of graft-versus-host disease, and changes in the immune status after infection could be responsible for the increase in non-relapse mortality. Therefore, appropriate control of CMV reactivation is crucial to improve outcomes. In contrast, several studies have reported that post-transplant CMV reactivation prevents acute myeloid leukemia relapse. Although the beneficial effect of CMV reactivation is debated, the increase and long-term persistence of mature NK cells that develop in response to CMV infection is considered a possible mechanism. However, the effects may vary according to the disease status, donor type, and transplantation method. Therefore, a detailed study is warranted to accurately assess the impact of post-transplant CMV reactivation.

 Blood transfusion medicine in Japan is supported by the blood donation system. The government has issued guidelines and standards of use to promote proper use, and the “Guidelines for the implementation of blood transfusion therapy” and the “Guidelines for the use of blood products” have come to be widely used as guidelines for proper use. Various safety measures have been taken to improve the safety of blood products, with which a significant improvement could be achieved. In 2003, the Act on Securing a Stable Supply of Safe Blood Products was enacted. Based on the basic principles of blood safety improvement and the domestic self-sufficiency through voluntary non-remunerated donation, securing stable blood supply, and promoting appropriate use of blood, in addition to ensuring fairness and improving transparency in business operations, the role of medical professionals involved in the blood transfusion chain has been clearly defined. The blood transfusion management system in medical institutions has been improved, and a system unique to Japan, which aims to achieve safe and appropriate blood transfusion practices through multidisciplinary blood transfusion medical care, has been implemented.

 Unrelated cord blood transplantation (CBT) is a crucial modality of allogeneic hematopoietic cell transplantation for patients lacking related and unrelated donors and those who require prompt transplantation. In contrast to CBT practices in Western countries, Japanese CBT exhibits several distinct characteristics, such as the utilization of single-unit cord blood for both pediatric and adult patients, looser criteria for cord blood unit selection, and expanded indications for advanced diseases. Therefore, clinical evidence for CBT needs to be established through single or multi-institutional studies within Japan. Advancements in supportive care, including more careful patient selection based on disease type and status, more stringent cord blood graft selection based on cryopreserved CD34⁺ cell dose and the presence of donor-specific anti-HLA antibodies, safer conditioning regimens, and optimal graft-versus-host disease (GVHD) prophylaxis, have likely contributed to the recent improvement in neutrophil engraftment and early mortality after CBT for adults. Additionally, the development of mild GVHD after CBT may enhance survival by decreasing relapse and non-relapse mortality, particularly for high-risk groups.

 Hematopoietic stem cell transplantation for malignant lymphoma (HSCT) is performed as consolidation therapy after induction therapy for selected disease types with high risk of relapse or that for relapsed/refractory cases. Regardless of the type or timing of treatment, HSCT should be performed in chemotherapy-sensitive cases; it has little prognostic value in chemotherapy-resistant patients. Polatuzumab vedotin for diffuse large B-cell lymphoma (DLBCL) and brentuximab vedotin for Hodgkin lymphoma and peripheral T-cell lymphoma are now part of first-line therapy for each disease type. CAR-T cell therapy has also been introduced for relapsed/refractory cases of DLBCL. The position of HSCT for malignant lymphoma continues to change with the development of new therapies, and the indications for HSCT need to be constantly reevaluated.

 Subsequent malignant neoplasms are the most common late complication after hematopoietic cell transplantation (HCT), and are classified into post-transplant lymphoproliferative disorder (PTLD), myeloid neoplasms following HCT, and subsequent solid cancers. PTLD usually occurs within 1 year after HCT, with incidences of 0.1% after autologous HCT and 0.8% after allogenic HCT. T-cell depletion, aplastic anemia, unrelated donor, HLA mismatch, and cord blood graft are associated with PTLD development. Myeloid neoplasms usually occur within a few years after HCT, with incidences of 2.3% after autologous HCT and 0.4% after allogenic HCT. One-third of cases exhibit chromosome 5 or 7 abnormalities and have dismal survival. Subsequent solid cancers start to occur a few years after HCT, with no plateau. The incidence is 4% at 20 years after allogeneic HCT. Oropharyngeal cancer, esophageal cancer, and colorectal cancer are most common in Japanese patients, and the standardized incidence ratios of these cancers are 7 to 16-fold higher than in the general population. Most subsequent solid cancers occur at younger ages than in the general population, and well-established risk factors are chronic graft-versus-host disease, long-term use of immunosuppressive medications, prior radiation therapy, and younger or older age at HCT.

 Recently, allogeneic stem cell transplantation (allo-SCT) has increased in elderly patients due to the widespread use of reduced-intensity conditioning regimens and improved supportive care. However, physicians mostly determined indications empirically because it is difficult to judge the indication for allo-SCT in the elderly objectively.

 We investigated the usefulness of the G8 screening tool, a simple test developed to identify older patients who could benefit from a comprehensive geriatric assessment, in determining the indication for transplantation in the elderly. Between January 2011 and December 2021, Fifty-four patients aged 65 years or older who underwent their first allogeneic stem cell transplant at our hospital were included. We examined the relationship between G8 screening tool scores and whether the patient was in-hospital dead or discharged. In patients who could be discharged, G8 screening tool scores were significantly higher than in patients in-hospital death. According to ROC curve, the cut-off value of the G8 screening tool score for predicting mortality is 10.0. In the analysis using this cut-off value, there was a significant difference in overall survival. The G8 screening tool score is useful in deciding whether or not to SCT an elderly patient and can be used to predict prognosis.

 Extracorporeal photopheresis (ECP) has been approved by the Japanese regulatory authorities in December 2020 as a specially controlled medical device for second-line treatment of chronic graft-versus-host disease (GVHD) based on the results of a clinical study in patients with steroid-refractory, -dependent, or -intolerant chronic GVHD. The present study included 15 patients registered with the clinical study, and we performed post-hoc analysis to evaluate the therapeutic effect and safety up to 36 weeks after the start of ECP therapy. Three patients discontinued the study, and 12 patients completed up to Week 36. The steroid dose was decreased in 11/12 patients at Week 36. Patients with shorter duration of chronic GVHD at the start of ECP therapy tended to show greater reduction in steroid dose at Week 36. Mean change in individual organ-specific scores showed improvement as follows: mouth: after Week 4, skin and joint/fascia: after Week 8, and eyes: after Week 12. Notably, these improvements were maintained until Week 36. Patients’ general condition improved or was maintained at baseline levels in 11/12 patients at Week 36. With regard to quality of life evaluation, “pain/discomfort” and “self-care” scores improved over time.

 Reports of thyrotoxicosis and hypothyroidism occurring immediately after allogeneic stem cell transplantation are limited, and the detailed mechanisms remain unclear. Here, we present the case of a man in his 20s with thyrotoxicosis and hypothyroidism that occurred early after cord blood transplantation (CBT), with histopathology suggesting an immune reaction in the thyroid gland. The patient had acute myeloid leukemia and underwent a second CBT procedure. The patient developed thyrotoxicosis on day 43. The patient’s condition initially improved with increasing immunosuppressive drug doses; however, he later developed hypothyroidism and required thyroid hormone replacement therapy. Since conventional subacute thyroiditis, Graves’ disease, and Hashimoto’s thyroiditis were excluded due to the lack of histological evidence and autoantibodies, acute graft-versus-host disease (GVHD) was considered the main cause of thyroiditis. The possibility of even minor post-transplant thyroid function abnormalities is more common than expected and further studies are required.

 The duration of infectivity associated with severe acute respiratory coronavirus-2 (SARS-CoV-2) is generally approximately 10 days from the onset of symptoms. However, some studies have reported that this period may be longer than 20 days in patients with allogeneic hematopoietic stem cell transplantation (HSCT). Herein, we report a case of persistent viral SARS-CoV-2 shedding for 126 days in an individual with HSCT. When the patient was infected with coronavirus disease 2019 (COVID-19), tacrolimus and prednisolone were administered for graft versus host disease. The viral load, which was monitored regularly by quantitative antigen testing, decreased with the administration of antiviral agents but re-elevated rapidly after discontinuation. Tapering of tacrolimus and prednisolone resulted in a gradual reduction of the viral load and its eventual disappearance. This case report highlights the importance of determining persistent infectivity in patients with allogeneic HSCT using viral testing prior to release from isolation.