The purpose of this trial was to evaluate the efficacy of 2-year consolidation therapy with nilotinib, at a dose of 300 mg twice daily, for achieving treatment-free remission in chronic myeloid leukemia patients with a deep molecular response (BCR-ABL1IS ≤0.0032%). Successful treatment-free remission was defined as no confirmed loss of deep molecular response. We recruited 96 Japanese patients, of whom 78 sustained a deep molecular response during the consolidation phase and were therefore eligible to discontinue nilotinib in the treatment-free remission phase; of these, 53 patients (67.9%; 95% confidence interval: 56.4–78.1%) remained free from molecular recurrence in the first 12 months. The estimated 3-year treatment-free survival was 62.8%. Nilotinib was readministered to all patients (n=29) who experienced a molecular recurrence during the treatment-free remission phase. After restarting treatment, rapid deep molecular response returned in 25 patients (86.2%), with 50% of patients achieving a deep molecular response within 3.5 months. Tyrosine kinase inhibitor withdrawal syndrome was reported in 11/78 patients during the early treatment-free remission phase. The treatment-free survival curve was significantly better in patients with undetectable molecular residual disease than in patients without (3-year treatment-free survival, 75.6 versus 48.6%, respectively; P=0.0126 by the log-rank test). There were no significant differences in treatment-free survival between subgroups based on tyrosine kinase inhibitor treatment before the nilotinib consolidation phase, tyrosine kinase inhibitor-withdrawal syndrome, or absolute number of natural killer cells. The results of this study indicate that it is safe and feasible to stop tyrosine kinase inhibitor therapy in patients with chronic myeloid leukemia who have achieved a sustained deep molecular response with 2 years of treatment with nilotinib. This study was registered with UMIN-CTR (UMIN000005904).

Hemophagocytic syndrome (HPS) presents with fever, pancytopenia, liver dysfunction and increase in hemophagocytic histiocytes in various organs. Although there are two major classifications of HPS in adults, malignant and reactive histiocytosis, it is often very difficult to distinguish between these disorders. We analyzed the laboratory data of patients with HPS to evaluate prognostic factors. Of 34 patients, 14 survived, and 20 died. The median age of survivors was 29.6 ± 11.5 yr significantly younger than those who died (54.7 ± 17.8 yr). Twenty patients had no obvious underlying disease, the other 13 had hematological malignancies or viral infections. Comparison of laboratory data revealed that nonsurvivors had significantly lower Hb and platelet values on admission. During treatment, worsening of anemia and thrombocytopenia, increase of transaminase and biliary enzymes were similarly more prominent. Risk factors associated with death were: age over 30 yr, presence of disseminated intravascular coagulation, increased ferritin and β2‐microglobulin, anemia accompanied by thrombocytopenia and jaundice. Our data suggests that patients with HPS and any of these risk factors should be treated aggressively with sufficient chemotherapy and supportive care.

Summary. There is an increasing incidence of the evolution of myelodysplastic syndrome (MDS) from aplastic anaemia (AA) with immunosuppressive treatment. In paediatric patients G-CSF is also reported to increase MDS evolution, but this process is not precisely understood in children or in adults. Therefore risk factors of MDS evolution in adults are evaluated here. Of 72 patients, five developed MDS. In 47 patients without cyclosporine (CyA) or antithymocyte globulin (ATG) therapy, only one developed MDS with trisomy 8, 242 months after diagnosis. But of 25 patients treated with either CyA or ATG, four developed monosomy 7 MDS within 3 years. Of these 25 patients, 18 were treated with G-CSF and the four patients (22·2%) who developed MDS were found in this group. The cumulative dose and the duration of G-CSF administration were significantly elevated in patients who developed MDS when compared with those who did not, 822·3 Ϯ 185·0 v 205·4 Ϯ 25·5 mg/kg (P < 0·05) and 187·5 Ϯ 52·5 v 72·0 Ϯ 24·6 d (P < 0·002), respectively. However these two values for CyA did not differ significantly. Statistically, treatment with CyA, G-CSF and combined G-CSF and CyA were significantly related to MDS evolution. The administration of G-CSF for more than a year was the most important factor (P ¼ 0·00). These results suggested that a close relationship exists between G-CSF and subsequent monosomy 7 MDS from AA in adults who receive immunosuppressive therapy. Long-term administration of G-CSF should be prohibited in order to prevent MDS evolution.

Tyrosine kinase inhibitors (TKI) improve the prognosis of patients with chronic myelogenous leukemia (CML) by inducing substantial deep molecular responses (DMR); some patients have successfully discontinued TKI therapy after maintaining DMR for ≥1 year. In this cessation study, we investigated the optimal conditions for dasatinib discontinuation in patients who maintained DMR for ≥2 years. This study included 54 patients with CML who were enrolled in a D‐STOP multicenter prospective trial, had achieved DMR, and had discontinued dasatinib after 2‐year consolidation. Peripheral lymphocyte profiles were analyzed by flow cytometry. The estimated 12‐month treatment‐free survival (TFS) was 62.9% (95% confidence interval: 48.5%‐74.2%). During dasatinib consolidation, the percentage of total lymphocytes and numbers of CD3− CD56+ natural killer (NK) cells, CD16+ CD56+ NK cells and CD56+ CD57+ NK‐large granular lymphocytes (LGL) were significantly higher in patients with molecular relapse after discontinuation but remained unchanged in patients without molecular relapse for >7 months. At the end of consolidation, patients whose total lymphocytes comprised <41% CD3− CD56+ NK cells, <35% CD16+ CD56+ NK cells, or <27% CD56+ CD57+ NK‐LGL cells had higher TFS relative to other patients (77% vs 18%; P < .0008; 76% vs 10%; P < .0001; 84% vs 46%; P = .0059, respectively). The increase in the number of these NK cells occurred only during dasatinib consolidation. In patients with DMR, dasatinib discontinuation after 2‐year consolidation can lead to high TFS. This outcome depends significantly on a smaller increase in NK cells during dasatinib consolidation.