Viral antigen mismatch affects antiviral T-cell response and may impair immunotherapeutic efficacy against adult T-cell leukemia/lymphoma.

HTLV-1 transforms primary CD4+ T cells in vitro within a short time; however, majority of infected individuals maintain an asymptomatic condition, suggesting there is an equilibrium between the infected cells and the host immunity. In this study, we identified a variation in a major viral antigen epitope, HTLV-1 Tax301-309, in HLA-A24-positive individuals. Mismatch in A24/Tax301-309 multimers impaired detection of anti-Tax CTLs. Notably, over half of the TCRs of the anti-Tax CTLs did not recognize mismatched Tax301-309 peptides. These findings highlighted the importance of matching the viral antigen epitope type in T-cell-based immunotherapy against ATL by using viral antigen Tax.

Impaired humoral immunity following COVID-19 vaccination in HTLV-1 carriers.

BACKGROUND: Whether human T-lymphotropic virus type 1 (HTLV-1) carriers can develop sufficient humoral immunity after coronavirus disease 2019 (COVID-19) vaccination is unknown. METHODS: To investigate humoral immunity after COVID-19 vaccination in HTLV-1 carriers, a multicenter, prospective observational cohort study was conducted at five institutions in southwestern Japan, an endemic area for HTLV-1. HTLV-1 carriers and HTLV-1-negative controls were enrolled for this study from January to December 2022. During this period, the third dose of the COVID-19 vaccine was actively administered. HTLV-1 carriers were enrolled during outpatient visits, while HTLV-1-negative controls included health care workers and patients treated by participating institutions for diabetes, hypertension, or dyslipidemia. The main outcome was the effect of HTLV-1 infection on the plasma anti-COVID-19 spike IgG (IgG-S) titers after the third dose, assessed by multivariate linear regression with other clinical factors. RESULTS: We analyzed 181 cases (90 HTLV-1 carriers, 91 HTLV-1-negative controls) after receiving the third dose. HTLV-1 carriers were older (median age 67.0 vs. 45.0 years, p < 0.001) and more frequently had diabetes, hypertension, or dyslipidemia than did HTLV-1-negative controls (60.0% vs. 27.5%, p < 0.001). After the third dose, the IgG-S titers decreased over time in both carriers and controls. Multivariate linear regression in the entire cohort showed that time since the third dose, age, and HTLV-1 infection negatively influenced IgG-S titers. After adjusting for confounders such as age, or presence of diabetes, hypertension, or dyslipidemia between carriers and controls using the overlap weighting propensity score method, and performing weighted regression analysis in the entire cohort, both time since the third dose and HTLV-1 infection negatively influenced IgG-S titers. CONCLUSIONS: The humoral immunity after the third vaccination dose is impaired in HTLV-1 carriers; thus, customized vaccination schedules may be necessary for them.

M-Sec induced by HTLV-1 mediates an efficient viral transmission.

Human T-cell leukemia virus type 1 (HTLV-1) infects target cells primarily through cell-to-cell routes. Here, we provide evidence that cellular protein M-Sec plays a critical role in this process. When purified and briefly cultured, CD4+ T cells of HTLV-1 carriers, but not of HTLV-1- individuals, expressed M-Sec. The viral protein Tax was revealed to mediate M-Sec induction. Knockdown or pharmacological inhibition of M-Sec reduced viral infection in multiple co-culture conditions. Furthermore, M-Sec knockdown reduced the number of proviral copies in the tissues of a mouse model of HTLV-1 infection. Phenotypically, M-Sec knockdown or inhibition reduced not only plasma membrane protrusions and migratory activity of cells, but also large clusters of Gag, a viral structural protein required for the formation of viral particles. Taken together, these results suggest that M-Sec induced by Tax mediates an efficient cell-to-cell viral infection, which is likely due to enhanced membrane protrusions, cell migration, and the clustering of Gag.

Integrated genetic and clinical prognostic factors for aggressive adult T-cell leukemia/lymphoma.

The prognosis of aggressive adult T-cell leukemia/lymphoma (ATL) is poor, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment. In order to identify favorable prognostic patients after intensive chemotherapy, and who therefore might not require upfront allo-HSCT, we aimed to improve risk stratification of aggressive ATL patients aged <70 years. The clinical risk factors and genetic mutations were incorporated into risk modeling for overall survival (OS). We generated the m7-ATLPI, a clinicogenetic risk model for OS, that included the ATL prognostic index (PI) (ATL-PI) risk category, and non-silent mutations in seven genes, namely TP53, IRF4, RHOA, PRKCB, CARD11, CCR7, and GATA3. In the training cohort of 99 patients, the m7-ATLPI identified a low-, intermediate-, and highrisk group with 2-year OS of 100%, 43%, and 19%, respectively (hazard ratio [HR] =5.46; P<0.0001). The m7-ATLPI achieved superior risk stratification compared to the current ATL-PI (C-index 0.92 vs. 0.85, respectively). In the validation cohort of 84 patients, the m7-ATLPI defined low-, intermediate-, and high-risk groups with a 2-year OS of 81%, 30%, and 0%, respectively (HR=2.33; P=0.0094), and the model again outperformed the ATL-PI (C-index 0.72 vs. 0.70, respectively). The simplified m7-ATLPI, which is easier to use in clinical practice, achieved superior risk stratification compared to the ATLPI, as did the original m7-ATLPI; the simplified version was calculated by summing the following: high-risk ATL-PI category (+10), low-risk ATL-PI category (-4), and non-silent mutations in TP53 (+4), IRF4 (+3), RHOA (+1), PRKCB (+1), CARD11 (+0.5), CCR7 (-2), and GATA3 (-3).

Identification of putative noncanonical driver mutations in patients with essential thrombocythemia.

Essential thrombocythemia (ET) cases without canonical JAK2, CALR, or MPL mutations, that is, triple-negative (TN) ET, have been found in 10%-20% of ET cases. Owing to the limited number of TN ET cases, its clinical significance remains unclear. This study evaluated TN ET's clinical characteristics and identified novel driver mutations. Among 119 patients with ET, 20 (16.8%) had no canonical JAK2/CALR/MPL mutations. Patients with TN ET tended to be younger and had lower white blood cell counts and lactate dehydrogenase values. We identified putative driver mutations in 7 (35%): MPL S204P, MPL L265F, JAK2 R683G, and JAK2 T875N were previously reported as candidate driver mutations in ET. Moreover, we identified a THPO splicing site mutation, MPL*636Wext*12, and MPL E237K. Four of the seven identified driver mutations were germline. Functional studies on MPL*636Wext*12 and MPL E237K revealed that they are gain-of-function mutants that increase MPL signaling and confer thrombopoietin hypersensitivity with very low efficiency. Patients with TN ET tended to be younger, although this was thought to be due to the inclusion of germline mutations, hereditary thrombocytosis. Accumulating the genetic and clinical characteristics of noncanonical mutations may help future clinical interventions in TN ET and hereditary thrombocytosis.

CCR7 alterations associated with inferior outcome of adult T-cell leukemia/lymphoma under mogamulizumab treatment.

Adult T-cell leukemia/lymphoma (ATL) patients have a very poor prognosis. The humanized anti-CCR4 therapeutic monoclonal antibody, mogamulizumab, is a key agent for ATL treatment. Our previous integrated molecular analysis demonstrated that among all the driver genes in ATL, CCR7 gene alterations were significantly associated with clinical response to mogamulizumab. Accordingly, here we investigated the detailed clinical impact of CCR7 alterations in a larger cohort of ATL patients. These CCR7 alterations, most of which lead to C-terminus truncations, were observed in 27 of 223 patients (12%). For patients receiving mogamulizumab but not allogeneic hematopoietic stem cell transplantation (HSCT), CCR7 alterations were significantly associated with worse survival (median survival from the first dose of mogamulizumab of 0.7 years for 12 patients with CCR7 alterations vs. 1.6 years for 72 patients without, p = 0.020). On the other hand, the presence or absence of CCR7 alterations had no significant impact on survival in the entire cohort (median overall survival of 1.4 and 1.8 years, respectively, p = 0.901), or on the survival of patients receiving allogeneic HSCT (median survival from the day of transplantation of 0.9 years for 6 patients with CCR7 alterations and 1.4 years for 48 without, p = 0.543). Multivariate analysis indicated that patients with CCR4 alterations but lacking CCR7 alterations (n = 20) had significantly better survival after receiving mogamulizumab-containing treatments (hazard ratio for survival, 0.437, 95% confidence interval, 0.192-0.994). This study contributes to the establishment of precision medicine for ATL.

Clinical significance of TP53 mutations in adult T-cell leukemia/lymphoma.

Adult T-cell leukaemia/lymphoma (ATL) patients have a poor prognosis. Here, we investigated the impact of TP53 gene mutations on prognosis of ATL treated in different ways. Among 177 patients, we identified 47 single nucleotide variants or insertion-deletions (SNVs/indels) of the TP53 gene in 37 individuals. TP53 copy number variations (CNVs) were observed in 38 patients. Altogether, 67 of 177 patients harboured TP53 SNVs/indels or TP53 CNVs, and were categorized as having TP53 mutations. In the entire cohort, median survival of patients with and without TP53 mutations was 1·0 and 6·7 years respectively (P < 0·001). After allogeneic haematopoietic stem cell transplantation (HSCT), median survival of patients with (n = 16) and without (n = 29) TP53 mutations was 0·4 years and not reached respectively (P = 0·001). For patients receiving mogamulizumab without allogeneic HSCT, the median survival from the first dose of antibody in patients with TP53 mutations (n = 27) was only 0·9 years, but 5·1 years in those without (n = 42; P < 0·001). Thus, TP53 mutations are associated with unfavourable prognosis of ATL, regardless of treatment strategy. The establishment of alternative modalities to overcome the adverse impact of TP53 mutations in patients with ATL is required.

Single response assessment of transplant-ineligible multiple myeloma: a supplementary analysis of JCOG1105 (JCOG1105S1).

BACKGROUND: The International Myeloma Working Group response criteria require two consecutive assessments of paraprotein levels. We conducted an exploratory analysis to evaluate whether a single response assessment could be a substitute for the International Myeloma Working Group criteria using data from JCOG1105, a randomized phase II study on melphalan, prednisolone and bortezomib. METHODS: Of 91 patients with transplant-ineligible newly diagnosed multiple myeloma, 79 patients were included. We calculated the kappa coefficient to evaluate the degree of agreement between the International Myeloma Working Group criteria and the single response assessment. RESULTS: Based on the International Myeloma Working Group criteria, 11 (13.9%), 20 (25.3%), 36 (45.6%) and 12 (15.2%) patients had stringent complete response/complete response, very good partial response, partial response and stable disease, respectively. Based on the single response assessment, 17 (21.5%), 19 (24.1%), 35 (44.3%) and 8 (10.1%) patients had stringent complete response/complete response, very good partial response, partial response and stable disease, respectively. The kappa coefficient was 0.76 (95% confidence interval, 0.65-0.88), demonstrating good agreement. The single response assessment was not inferior to the International Myeloma Working Group criteria in the median progression-free survival (3.8 and 2.9 years) in stringent complete response/complete response patients, suggesting that the single response assessment was not an overestimation. CONCLUSIONS: The single response assessment could be a substitute for the current International Myeloma Working Group criteria for transplant-ineligible newly diagnosed multiple myeloma.

Effect of exercise therapy on muscle mass and physical functioning in patients undergoing allogeneic hematopoietic stem cell transplantation.

PURPOSE: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with transplant-related toxicities, which may have a profound impact on a patient's physical functioning and body composition. In order to analyze the effect of exercise therapy on muscle mass and physical functioning in patients receiving allo-HSCT, we measured muscle mass and physical functioning before and after allo-HSCT. METHODS: Eighty-six patients who had undergone allo-HSCT between February 2010 and September 2013 at Imamura Bun-in Hospital participated in this study. Physical therapists performed exercise therapy with patients 5 days a week, starting 2 weeks before allo-HSCT. Body composition, 6-min walk test (6MWT) scores, and handgrip strength were evaluated 2 weeks before allo-HSCT and 6 weeks after allo-HSCT. RESULTS: Thirty-five patients were available for evaluation 2 weeks before and 6 weeks after allo-HSCT. The 6MWT (p = 0.005) and handgrip strength (p < 0.001) significantly decreased after allo-HSCT. Although upper extremity muscle mass (p = 0.001) and trunk muscle mass (p < 0.001) significantly decreased after allo-HSCT, lower extremity muscle mass remained unchanged. CONCLUSIONS: In this study, it is suggested that exercise therapy may be effective for maintaining lower extremity muscle mass in patients undergoing allo-HSCT.

Recovery of physical function, muscle mass, and quality of life in patients undergoing allogeneic hematopoietic stem cell transplantation.

This study aimed to investigate the recovery of physical function, muscle mass, and quality of life (QOL) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients 1 year after the procedure. A total of 71 patients who underwent allo-HSCT at our institution between February 2010 and June 2020, for whom a physical therapy assessment could be performed before allo-HSCT, at discharge, and 1 year after the procedure, were included. Exercise therapy during hospitalization was provided individually by a physical therapist, and exercise was self-administered after discharge. One year after allo-HSCT, handgrip strength and results of the 6-minute walk test recovered to pre-HSCT levels. However, muscle mass 1 year after allo-HSCT did not reach the pre-HSCT level. All subscales of QOL, 1 year after allo-HSCT, recovered to pre-HSCT levels, but only two of the eight subscales recovered to the national standard of 50. Multivariate analysis revealed factors associated with the recovery of physical function, muscle mass, and QOL, hemoglobin levels and albumin levels, especially among men. In contrast, factors that negatively affected recovery were age, acute graft-versus-host disease, and pre-HSCT intensity conditioning. The results suggest a potential recovery in handgrip strength, endurance, and QOL 1 year after allo-HSCT.

A decrease in newly diagnosed patients with adult T-cell leukemia/lymphoma in Kagoshima, a highly endemic area of HTLV-1 in southwestern Japan.

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell malignancy caused by human T-cell leukemia virus type-I (HTLV-1). This study investigated whether the number of newly diagnosed patients with ATL is decreasing in the background of a declining number of individuals infected by HTLV-1 in Kagoshima, Japan, one of the most endemic areas of HTLV-1 in the world. We retrospectively analyzed the number of newly diagnosed patients with ATL between January 2001 and December 2021 in three major hospitals. The number of newly diagnosed patients with B-cell non-Hodgkin lymphoma (B-NHL) in the same period was examined as an internal control. One thousand eighteen and 2,029 patients with ATL and B-NHL were registered, respectively. The age-adjusted incidence of ATL steadily increased between 2001 and 2012, whereas that between 2013 and 2021 decreased. Despite the limitation of its retrospective nature, this is the first report indicating a decrease in ATL patients in Japan.

Performance evaluation of Espline HTLV-I/II, a newly developed rapid immunochromatographic antibody test for different diagnostic situations.

IMPORTANCE: The World Health Organization estimated that 5-10 million people are infected with human T-cell leukemia virus type 1 (HTLV-1). This number is likely to be underestimated because reliable endemic data are available for only approximately 1.5 billion people worldwide. The point-of-care test is a powerful tool for the easy and quick detection of infections without the requirement for expensive instruments and laboratory equipment. Espline HTLV-I/II, a newly developed rapid immunochromatographic antibody test that was evaluated in this study, might significantly advance our understanding of the global epidemiology of HTLV-1 infection.

Identification and characterization of a novel enhancer in the HTLV-1 proviral genome.

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that causes adult T-cell leukemia/lymphoma (ATL), a cancer of infected CD4+ T-cells. There is both sense and antisense transcription from the integrated provirus. Sense transcription tends to be suppressed, but antisense transcription is constitutively active. Various efforts have been made to elucidate the regulatory mechanism of HTLV-1 provirus for several decades; however, it remains unknown how HTLV-1 antisense transcription is maintained. Here, using proviral DNA-capture sequencing, we found a previously unidentified viral enhancer in the middle of the HTLV-1 provirus. The transcription factors, SRF and ELK-1, play a pivotal role in the activity of this enhancer. Aberrant transcription of genes in the proximity of integration sites was observed in freshly isolated ATL cells. This finding resolves certain long-standing questions concerning HTLV-1 persistence and pathogenesis. We anticipate that the DNA-capture-seq approach can be applied to analyze the regulatory mechanisms of other oncogenic viruses integrated into the host cellular genome.

GVHD-free, relapse-free survival provides novel clues for optimizing allogeneic-HSCT for adult T-cell leukemia/lymphoma.

The outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for adult T-cell leukemia/lymphoma (ATL) is still unsatisfactory. To illustrate the advantages and disadvantages of each donor source, we performed a nationwide retrospective study of graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) of patients with allo-HSCT-treated ATL. One-year GRFS did not significantly differ between patients who received related bone marrow transplantation (R-BMT; 26%, n = 117), related peripheral blood stem cell transplantation (R-PBSCT; 22%, n = 225), unrelated bone marrow transplantation (UR-BMT; 26%, n = 619), and cord blood transplantation (CBT; 21%, n = 359; p = 0.09). This was attributable to a low incidence of systemically-treated chronic GVHD after CBT (9% at 1 year) and reduced non-GVHD/relapse mortality after R-PBSCT (9% at 1 year). Among patients transplanted in complete remission (CR), 1-year overall survival after CBT (52%, n = 132) was not inferior to that after R-BMT (55%, n = 51), R-PBSCT (57%, n = 79), and UR-BMT (58%, n = 280; p = 0.15), and relapse rates were equivalent among the four sources (p = 0.19). Our results suggest that all donor sources are feasible for CR patients and that GRFS provides important clues toward optimizing allo-HSCT for ATL.

Cord blood transplantation with a reduced-intensity conditioning regimen using fludarabine and melphalan for adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma with a poor prognosis when treated with chemotherapy alone; therefore, allogeneic stem cell transplantation is a consideration. We attempted cord blood transplantation (CBT) using a reduced-intensity conditioning regimen without total body irradiation (non-TBI-RIC) to allow for the best possible timing of transplantation and improve survival outcomes, particularly in older patients. Forty-eight patients (27 male, 21 female) underwent CBT using fludarabine (Flu) 125 mg/m2 and melphalan (Mel) 140 mg/m2 as pre-transplant conditioning. The median age was 32 years (range 44-72), and 21 patients were in complete remission (CR) at the time of CBT. The median duration to neutrophil engraftment (NE) was 19.5 days (range 15-50), with a cumulative incidence of NE of 86.7% at day 50 after CBT. The 1- and 3-year overall survival (OS) rates were 40.4% and 37.7%, respectively. The 3-year OS rate in CR patients was 60.8%, compared with 18.8% in non-CR patients. In ATLL patients, CBT with non-TBI-RIC using Flu/Mel is a promising treatment strategy.