Summary: For successful chimeric antigen receptor T (CAR‐T) cell therapy, CAR‐T cells must be manufactured without failure caused by suboptimal expansion. In order to determine risk factors for CAR‐T cell manufacturing failure, we performed a nationwide cohort study in Japan and analysed patients with diffuse large B‐cell lymphoma (DLBCL) who underwent tisagenlecleucel production. We compared clinical factors between 30 cases that failed (7.4%) with those that succeeded (n = 378). Among the failures, the proportion of patients previously treated with bendamustine (43.3% vs. 14.8%; p < 0.001) was significantly higher, and their platelet counts (12.0 vs. 17.0 × 10⁴/μL; p = 0.01) and CD4/CD8 T‐cell ratio (0.30 vs. 0.56; p < 0.01) in peripheral blood at apheresis were significantly lower than in the successful group. Multivariate analysis revealed that repeated bendamustine use with short washout periods prior to apheresis (odds ratio [OR], 5.52; p = 0.013 for ≥6 cycles with washout period of 3–24 months; OR, 57.09; p = 0.005 for ≥3 cycles with washout period of <3 months), low platelet counts (OR, 0.495 per 10⁵/μL; p = 0.022) or low CD4/CD8 ratios (<one third) (OR, 3.249; p = 0.011) in peripheral blood at apheresis increased the risk of manufacturing failure. Manufacturing failure remains an obstacle to CAR‐T cell therapy for DLBCL patients. Avoiding risk factors, such as repeated bendamustine administration without sufficient washout, and risk‐adapted strategies may help to optimize CAR‐T cell therapy for DLBCL patients.

Intestinal flora plays an essential role in regulating immune responses. Changes in the gut flora are associated with poor prognosis after allogeneic hematopoietic stem cell transplantation (HSCT). We aimed to investigate the impact of diverse intestinal flora on survival after allogeneic HSCT. Using next-generation sequencing of the bacterial 16S ribosomal RNA (rRNA) gene, we found that the intestinal microbiota of patients undergoing allogeneic HSCT differed significantly from that of healthy controls. Furthermore, dysbiosis persisted for at least 1 year after transplantation. Interestingly, increased abundance of the genus Enterococcus detected by 16S rRNA sequencing as early as 1 month after transplantation was correlated with poor survival (overall survival at 2 years post-HSCT, 83.9% for patients with <1% relative abundance of Enterococcus and 47.6% for those with ≥1% relative abundance of Enterococcus), which was undetectable by conventional standard stool culture. These findings suggest that detection of Enterococcus by 16S rRNA analysis reflects compromised intestinal flora and may be a promising prognostic indicator.

KIT is a type-III receptor tyrosine kinase that contributes to cell signaling in various cells. Since KIT is activated by overexpression or mutation and plays an important role in the development of some cancers, such as gastrointestinal stromal tumors and mast cell disease, molecular therapies targeting KIT mutations are being developed. In acute myeloid leukemia (AML), genome profiling via next-generation sequencing has shown that several genes that are mutated in patients with AML impact patients’ prognosis. Moreover, it was suggested that precision-medicine-based treatment using genomic data will improve treatment outcomes for AML patients. This paper presents (1) previous studies regarding the role of KIT mutations in AML, (2) the data in AML with KIT mutations from the HM-SCREEN-Japan-01 study, a genome profiling study for patients newly diagnosed with AML who are unsuitable for the standard first-line treatment (unfit) or have relapsed/refractory AML, and (3) new therapies targeting KIT mutations, such as tyrosine kinase inhibitors and heat shock protein 90 inhibitors. In this era when genome profiling via next-generation sequencing is becoming more common, KIT mutations are attractive novel molecular targets in AML.

In patients undergoing haematopoietic stem-cell transplantation (HSCT), the intestinal microbiota plays an important role in prognosis, transplant outcome, and complications such as graft-versus-host disease (GVHD). Our prior research revealed that patients undergoing HSCT substantially differed from healthy controls. In this retrospective study, we showed that administering Clostridium butyricum MIYAIRI 588 (CBM588) as a live biotherapeutic agent is associated with maintaining intestinal microbiota in the early post-HSCT period. Alpha diversity, which reflects species richness, declined considerably in patients who did not receive CBM588, whereas it remained consistent in those who received CBM588. In addition, β-diversity analysis revealed that CBM588 did not alter the gut microbiota structure at 7–21 days post-HSCT. Patients who developed GVHD showed structural changes in their microbiota from the pre-transplant period, which was noticeable on day 14 before developing GVHD. Enterococcus was significantly prevalent in patients with GVHD after HSCT, and the population of Bacteroides was maintained from the pre-HSCT period through to the post-HSCT period. Patients who received CBM588 exhibited a contrasting trend, with lower relative abundances of both genera Enterococcus and Bacteroides. These results suggest that preoperative treatment with CBM588 could potentially be beneficial in maintaining intestinal microbiota balance.