KW-0761 was tolerated at all the dose levels tested, demonstrating potential efficacy against relapsed CCR4-positive ATL or PTCL. Subsequent phase II studies at the 1.0 mg/kg dose are thus warranted.

Definitive risk factors for the development of adult T-cell leukemia (ATL) among asymptomatic human T-cell leukemia vi-

SummaryThis multicentre, randomized, phase II study was conducted to examine whether the addition of mogamulizumab, a humanized anti‐CC chemokine receptor 4 antibody, to mLSG15, a dose‐intensified chemotherapy, further increases efficacy without compromising safety of patients with newly diagnosed aggressive adult T‐cell leukaemia‐lymphoma (ATL). Patients were assigned 1:1 to receive mLSG15 plus mogamulizumab or mLSG15 alone. The primary endpoint was the complete response rate (%CR); secondary endpoints included the overall response rate (ORR) and safety. The %CR and ORR in the mLSG15‐plus‐mogamulizumab arm (n = 29) were 52% [95% confidence interval (CI), 33–71%] and 86%, respectively; the corresponding values in the mLSG15 arm (n = 24) were 33% (95% CI, 16–55%) and 75%, respectively. Grade ≥ 3 treatment‐emergent adverse events, including anaemia, thrombocytopenia, lymphopenia, leucopenia and decreased appetite, were observed more frequently (≥10% difference) in the mLSG15‐plus‐mogamulizumab arm. Several adverse events, including skin disorders, cytomegalovirus infection, pyrexia, hyperglycaemia and interstitial lung disease, were observed only in the mLSG15‐plus‐mogamulizumab arm. Although the combination strategy showed a potentially less favourable safety profile, a higher %CR was achieved, providing the basis for further investigation of this novel treatment for newly diagnosed aggressive ATL. This study was registered at ClinicalTrials.gov, identifier: NCT01173887.

Summary:Adult T cell leukemia/lymphoma (ATL) is a poor prognosis T cell malignancy. In order to improve the outcome, we employed allogeneic stem cell transplantation (allo-SCT) for ATL in 10 patients, nine of whom were from HLA-identical siblings and one from an unrelated donor. Conditioning regimens varied among the patients except that all received total body irradiation. The patients tolerated the regimens well with mild, if any toxicity, and engraftment occurred in all cases. Median leukemia-free survival after allo-SCT was 17.5+ months (range 3.7-34.4+). Six of the 10 patients developed acute GVHD (one case each with grade I, III or IV, and three cases with grade II) and three patients developed extensive chronic GVHD. Four patients died after allo-SCT during the study period from either acute GVHD (grade IV), pneumonitis, gastrointestinal bleeding or renal insufficiency. Two of the 10 cases with no symptoms of GVHD relapsed with clinical ATL. These results strongly suggest that allo-SCT may improve the survival in ATL if a controlled degree of GVHD develops. Bone Marrow Transplantation (2001) 27, 15-20.

Adult T-cell leukemia/lymphoma (ATLL) develops after infection with human T-cell leukemia virus-1 (HTLV-1) after a long latency period. The negative regulatory programmed death-1/ programmed death-1 ligand 1 (PD-1/PD-L1) pathway has been implicated in the induction of cytotoxic T-lymphocyte (CTL) exhaustion during chronic viral infection along with tumor escape from host immunity. To determine whether the PD-1/ PD-L1 pathway could be involved in the establishment of persistent HTLV-1 infections and immune evasion of ATLL cells in patients, we examined PD-1/PD-L1 expression on cells from 27 asymptomatic HTLV-1 carriers (ACs) and 27 ATLL patients in comparison with cells from 18 healthy donors. PD-1 expression on HTLV-1-specific CTLs from ACs and ATLL patients was dramatically elevated. In addition, PD-1 expression was significantly higher on CD8 þ T cells along with cytomegalovirus (CMV)-and Epstein-Barr virus (EBV)-specific CTLs in ATLL patients compared with ACs and control individuals. Primary ATLL cells in 21.7% of ATLL patients expressed PD-L1, whereas elevated expression was not observed in cells from ACs. Finally, in functional studies, we observed that an anti-PD-L1 antagonistic antibody upregulated HTLV-1-specific CD8 þ T-cell response. These observations suggest that the PD-1/ PD-L1 pathway plays a role in fostering persistent HTLV-1 infections, which may further ATLL development and facilitate immune evasion by ATLL cells.