Kimiharu Uozumi

Phase I Study of KW-0761, a Defucosylated Humanized Anti-CCR4 Antibody, in Relapsed Patients With Adult T-Cell Leukemia-Lymphoma and Peripheral T-Cell Lymphoma

PURPOSE KW-0761, a defucosylated humanized anti-CC chemokine receptor 4 (CCR4) antibody, exerts a strong antibody-dependent cellular cytotoxic effect. This phase I study assessed the safety, pharmacokinetics, recommended phase II dose and efficacy of KW-0761 in patients with relapsed CCR4-positive adult T-cell leukemia-lymphoma (ATL) or peripheral T-cell lymphoma (PTCL). PATIENTS AND METHODS Sixteen patients received KW-0761 once a week for 4 weeks by intravenous infusion. Doses were escalated, starting at 0.01, 0.1, 0.5, and finally 1.0 mg/kg by a 3 + 3 design. RESULTS Fifteen patients completed the protocol treatment. Only one patient, at the 1.0 mg/kg dose, developed grade 3 dose-limiting toxicities, skin rash, and febrile neutropenia, and grade 4 neutropenia. Other treatment-related grade 3 to 4 toxicities were lymphopenia (n = 10), neutropenia (n = 3), leukopenia (n = 2), herpes zoster (n = 1), and acute infusion reaction/cytokine release syndrome (n = 1). Neither the frequency nor severity of toxicities increased with dose escalation. The maximum tolerated dose was not reached. Therefore, the recommended phase II dose was determined to be 1.0 mg/kg. No patients had detectable levels of anti-KW-0761 antibody. The plasma maximum and trough, and the area under the curve of 0 to 7 days of KW-0761, tended to increase dose and frequency dependently. Five patients (31%; 95% CI, 11% to 59%) achieved objective responses: two complete (0.1; 1.0 mg/kg) and three partial (0.01; 2 at 1.0 mg/kg) responses. CONCLUSION 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.

Human T-cell leukemia virus type I (HTLV-1) proviral load and disease progression in asymptomatic HTLV-1 carriers: a nationwide prospective study in Japan

Definitive risk factors for the development of adult T-cell leukemia (ATL) among asymptomatic human T-cell leukemia virus type I (HTLV-1) carriers remain unclear. Recently, HTLV-1 proviral loads have been evaluated as important predictors of ATL, but a few small prospective studies have been conducted. We prospectively evaluated 1218 asymptomatic HTLV-1 carriers (426 males and 792 females) who were enrolled during 2002 to 2008. The proviral load at enrollment was significantly higher in males than females (median, 2.10 vs 1.39 copies/100 peripheral blood mononuclear cells [PBMCs]; P < .001), in those 40 to 49 and 50 to 59 years of age than that of those 40 years of age and younger (P = .02 and .007, respectively), and in those with a family history of ATL than those without the history (median, 2.32 vs 1.33 copies/100 PBMCs; P = .005). During follow-up, 14 participants progressed to overt ATL. Their baseline proviral load was high (range, 4.17-28.58 copies/100 PBMCs). None developed ATL among those with a baseline proviral load lower than approximately 4 copies. Multivariate Cox analyses indicated that not only a higher proviral load, advanced age, family history of ATL, and first opportunity for HTLV-1 testing during treatment for other diseases were independent risk factors for progression of ATL.

PD-1/PD-L1 expression in human T-cell leukemia virus type 1 carriers and adult T-cell leukemia/lymphoma patients

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+ 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+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.

Dose-intensified chemotherapy alone or in combination with mogamulizumab in newly diagnosed aggressive adult T-cell leukaemia-lymphoma: a randomized phase II study

This 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.

Expression of the multidrug transporter, P‐glycoprotein, in chronic myelogenous leukaemia cells in blast crisis

The overexpression of a cell‐surface glycoprotein termed P‐glycoprotein (P‐gp) is frequently associated with multidrug resistance (MDR) in cell lines in vitro. To evaluate the implications of P‐gp expression in clinical drug‐resistance, we examined the expression of P‐gp in fresh leukaemia cells from chronic myelogenous leukaemia (CML) patients in blast crisis. By using immunoblotting with a monoclonal antibody against P‐gp, C219, we showed that leukaemia cells from three CML patients in blast crisis were P‐gp negative at the stage when these patients were in complete remission, and that the cells showed high levels of P‐gp expression at times when the same patients had relapsed and had not responded to chemotherapy. Six out of 11 patients (nine in the refractory state) were P‐gp positive and they rarely responded to chemotherapy. These data suggest that the expression of P‐gp is closely associated with drug‐resistance in CML.

Reduced Frequency, Diversity, and Function of Human T Cell Leukemia Virus Type 1-Specific CD8+ T Cell in Adult T Cell Leukemia Patients

Human T cell lymphotropic virus type 1 (HTLV-1)-specific CTL are thought to be immune effectors that reduce the risk of adult T cell leukemia (ATL). However, in vivo conditions of anti-HTLV-1 CTL before and after ATL development have yet to be determined. To characterize anti-HTLV-1 CTL in asymptomatic HTLV-1 carriers (AC) and ATL patients, we analyzed the frequency and diversity of HTLV-1-specific CD8+ T cells in PBMC of 35 AC and 32 ATL patients using 16 distinct epitopes of HTLV-1 Tax or Env/HLA tetramers along with intracellular cytolytic effector molecules (IFN-γ, perforin, and granzyme B). Overall frequency of subjects possessing Tax-specific CD8+ T cells was significantly lower in ATL than AC (53 vs 90%; p = 0.001), whereas the difference in Env-specific CD8+ T cells was not statistically significant. AC possessed Tax11–19/HLA-A*0201-specific tetramer+ cells by 90% and Tax301–309/HLA-A*2402-specific tetramer+ cells by 92%. Some AC recognized more than one epitope. In contrast, ATL recognized only Tax11–19 with HLA-A*0201 and Tax301–309 with HLA-A*2402 at frequencies of 30 and 55%. There were also significant differences in percentage of cells binding Tax11–19/HLA-A*0201 and Tax301–309/HLA-A*2402 tetramers between AC and ATL. Anti-HTLV-1 Tax CD8+ T cells in AC and ATL produced IFN-γ in response to Tax. In contrast, perforin and granzyme B expression in anti-HTLV-1 CD8+ T cells of ATL was significant lower than that of AC. Frequency of Tax-specific CD8+ T cells in AC was related to proviral load in HLA-A*0201. These results suggest that decreased frequency, diversity, and function of anti-HTLV-1 Tax CD8+ T cell clones may be one of the risks of ATL development.

Arsenic trioxide inhibits growth of human T-cell leukaemia virus type I infected T-cell lines more effectively than retinoic acids.

Adult T‐cell leukaemia (ATL) is difficult to cure using conventional therapies. Recently the therapeutic possibility of retinoic acids (RA) has been reported. In this study, suppression of in vitro growth of human T‐cell leukaemia virus type I (HTLV‐I) infected T‐cell lines and fresh ATL cells by arsenic trioxide (As2O3) were evaluated by comparison with a series of RA derivatives. Proliferation of four HTLV‐I‐infected T‐cell lines was significantly reduced within 72 h by 1.0 μmol/l As2O3. Growth of two out of four HTLV‐I‐infected T‐cell lines was also inhibited by 1.0 μmol/l RA, but to a lesser extent than by As2O3. The mechanism of this growth inhibition was due to the induction of apoptosis. Apoptosis was also induced in fresh ATL cells from patients by As2O3, but far less by RA. As described in patients with acute promyelocytic leukaemia, 1.0 μmol/l of As2O3 can be safely achieved in the serum of patients; however, it is difficult to maintain this concentration of RA. In conclusion, As2O3 has therapeutic potential for the treatment of ATL and may be far more clinically beneficial than RA.

The prevalence of human T-cell leukemia virus type I infection in patients with hematologic and nonhematologic diseases in an adult T-cell leukemia-endemic area of Japan

In order to clarify the prevalence of human T‐cell leukemia virus type I (HTLV‐I) infection in the Kagoshima district, Japan, a highly endemic area for HTLV‐I, antibodies for HTLV‐I (anti‐HTLV‐I) were examined in the sera of 6167 from healthy residents and patients with various hematologic and nonhematologic diseases. In healthy residents, including blood donors, the prevalence of anti‐HTLV‐I was 11.9% (562/4741 persons). The prevalence increased with age, and was significantly higher in females than in males (P < 0.01). The prevalence of anti‐HTLV‐I in blood donors was 8.5%. In hematologic diseases, the prevalence of anti‐HTLV‐I was 98.3% in ATL, 28.9% in lymphoproliferative disorders except ATL, and 10.6% in myeloproliferative disorders. In nonhematologic diseases, the prevalence of anti‐HTLV‐I was shown to be 29.5% in pulmonary tuberculosis, 25.8% in leprosy, 33.8% in chronic renal failure (CRF), 21.9% in autoimmune diseases, and 47.8% in strongyloidiasis. The various diseases except myeloproliferative disorders had significantly higher prevalence of anti‐HTLV‐I than healthy residents (P < 0.01 or 0.05). For autoimmune diseases, the prevalence of anti‐HTLV‐I in patients with blood transfusion (55.6%) was higher than in those without blood transfusion (8.7%), and healthy residents. In hemodialysis patients with CRF who had received blood transfusions the prevalence of anti‐HTLV‐I increased with the number of blood transfusions. Therefore, HTLV‐I transmission via blood transfusion would partially explain these high prevalence of anti‐HTLV‐I. However, the prevalence of anti‐HTLV‐I in hemodialysis patients with CRF was statistically higher than that in healthy residents, regardless of blood transfusion (P < 0.01). Furthermore, hemodialysis patients showed significantly higher prevalence of anti‐HTLV‐I than healthy residents, even at a younger age. Patients with pulmonary tuberculosis and leprosy showed the same results as hemodialysis patients. These results suggest the possibility that HTLV‐I infection has some relation not only to ATL but also to other diseases. Therefore, it seems very important to halt the spread of HTLV‐I transmission as soon as possible.

Japan Clinical Oncology Group (JCOG) prognostic index and characterization of long-term survivors of aggressive adult T-cell leukaemia-lymphoma (JCOG0902A)

This study evaluated the clinical features of 276 patients with aggressive adult T‐cell leukaemia‐lymphoma (ATL) in 3 Japan Clinical Oncology Group (JCOG) trials. We assessed the long‐term survivors who survived >5 years and constructed a prognostic index (PI), named the JCOG‐PI, based on covariates obtained by Cox regression analysis. The median survival time (MST) of the entire cohort was 11 months. In 37 patients who survived >5 years, no disease‐related deaths in 10 patients with lymphoma‐type were observed in contrast to the 10 ATL‐related deaths in other types. In multivariate analysis of 193 patients, the JCOG‐PI based on corrected calcium levels and performance status identified moderate and high risk groups with an MST of 14 and 8 months respectively (hazard ratio, 1·926). The JCOG‐PI was reproducible in an external validation. Patients with lymphoma‐type who survived >5 years might have been cured. The JCOG‐PI is valuable for identifying patients with extremely poor prognosis and will be useful for the design of future trials combining new drugs or investigational treatment strategies.

Arsenic trioxide and the growth of human T-cell leukemia virus type I infected T-cell lines.

A novel therapeutic potential for acute promyelocytic leukemia using arsenic trioxide (As2O3) has been reported. Recent in vitro studies demonstrated that As2O3 effectively inhibits the growth of some cell lines derived from patients with malignant lymphoma, chronic lymphocytic leukemia and multiple myeloma. Adult T-cell leukemia (ATL) is an aggressive neoplasm of mature T-cell origin caused by human T-cell leukemia virus type-I (HTLV-I) the prognosis of which still remains very poor. A possible role of As2O3 for the treatment of ATL is demonstrated from evidence that As2O3 significantly inhibits the growth of HTLV-I infected T-cell lines and induces apoptosis in fresh ATL cells at clinically achievable concentration of the agent. The growth inhibition of As2O3 treated HTLV-I infected T-cell lines was induced by both apoptosis and G1 phase accumulation. Cleaved bcl-2 protein and an enhanced expression of bak protein in the cells were coincidentally observed during As2O3 treatment. A broad spectrum caspase inhibitor, z-Val-Ala-DL-Asp-fluoromethylketone inhibited the apoptosis induced by As2O3. Increased expression of p53, Cip1/p21 and Kip1/p27, and dephosphorylation of retinoblastoma protein (pRb) were detected in the As2O3 treated cells. In conclusion, As2O3 might become a new therapeutic tool in the treatment of ATL as As2O3 induces apoptosis by destruction of the bcl-2 protein and enhancement of the bak protein production proceeding to activate caspases, and also induces G1 phase accumulation by enhancement of p.53, Cipl/p21, Kipl/p27 and dephosphorylation of pRb to HTLV-I infected T-cell lines.