A phase II study of bortezomib in patients with relapsed or refractory aggressive adult T-cell leukemia/lymphoma

Ubiquitin: A double-edged sword in hepatitis B virus-induced hepatocellular carcinoma

Hepatitis B virus is one of the leading causes behind the neoplastic transformation of liver tissue and associated mortality. Despite the availability of many therapies and vaccines, the pathogenic landscape of the virus remains elusive; urging the development of novel strategies based on the fundamental infectious and transformative modalities of the virus-host interactome. Ubiquitination is a widely observed post-translational modification of several proteins, which either regulates the proteins' turnover or impacts their functionalities. In recent years, ample amount of literature has accumulated regarding the ubiquitination dynamics of the HBV proteins as well as the host proteins during HBV infection and carcinogenesis; with direct and detailed characterization of the involvement of HBV in these processes. Interestingly, while many of these ubiquitination events restrict HBV life cycle and carcinogenesis, several others promote the emergence of hepatocarcinoma by putting the virus in an advantageous position. This review sums up the snowballing literature on ubiquitination-mediated regulation of the host-HBV crosstalk, with special emphasis on its influence on the establishment and progression of hepatocellular carcinoma on a molecular level. With the advent of cutting-edge ubiquitination-targeted therapeutic approaches, the findings emanating from this review may potentiate the identification of novel anti-HBV targets for the formulation of novel anticancer strategies to control the HBV-induced hepato-carcinogenic process on a global scale.

Mutations in Ras homolog family member A in patients with peripheral T-cell lymphoma and implications for personalized medicine

Genome sequencing has revealed frequent mutations in Ras homolog family member A (RHOA) among various cancers with unique aberrant profiles and pathogenic effects, especially in peripheral T-cell lymphoma (PTCL). The discrete positional distribution and types of RHOA amino acid substitutions vary according to the tumor type, thereby leading to different functional and biological properties, which provide new insight into the molecular pathogenesis and potential targeted therapies for various tumors. However, the similarities and discrepancies in characteristics of RHOA mutations among various histologic subtypes of PTCL have not been fully elucidated. Herein we highlight the inconsistencies and complexities of the type and location of RHOA mutations and demonstrate the contribution of RHOA variants to the pathogenesis of PTCL by combining epigenetic abnormalities and activating multiple downstream pathways. The promising potential of targeting RHOA as a therapeutic modality is also outlined. This review provides new insight in the field of personalized medicine to improve the clinical outcomes for patients.

Inhibitory effect of a neddylation blockade on HTLV-1-infected T cells via modulation of NF-κB, AP-1, and Akt signaling

Adult T-cell leukemia (ATL), caused by HTLV-1, is the most lethal hematological malignancy. NEDD8-activating enzyme (NAE) is a component of the NEDD8 conjunction pathway that regulates cullin-RING ubiquitin ligase (CRL) activity. HTLV-1-infected T cells expressed higher levels of NAE catalytic subunit UBA3 than normal peripheral blood mononuclear cells. NAE1 knockdown inhibited proliferation of HTLV-1-infected T cells. The NAE1 inhibitor MLN4924 suppressed neddylation of cullin and inhibited the CRL-mediated turnover of tumor suppressor proteins. MLN4924 inhibited proliferation of HTLV-1-infected T cells by inducing DNA damage, leading to S phase arrest and caspase-dependent apoptosis. S phase arrest was associated with CDK2 and cyclin A downregulation. MLN4924-induced apoptosis was mediated by the upregulation of pro-apoptotic and downregulation of anti-apoptotic proteins. Furthermore, MLN4924 inhibited NF-κB, AP-1, and Akt signaling pathways and activated JNK. Therefore, neddylation inhibition is an attractive strategy for ATL therapy. Our findings support the use of MLN4924 in ATL clinical trials.

Treatment of Adult T-Cell Leukemia/Lymphoma: Established Paradigms and Emerging Directions

OPINION STATEMENT

Adult T-cell leukemia/lymphoma (ATL) is a rare, aggressive subtype of peripheral T-cell lymphoma developing after many years of chronic, asymptomatic infection with the retrovirus human T-cell lymphotropic virus type 1 (HTLV-1). HTLV-1 is endemic to certain geographic areas of the world, and primary infection generally occurs in infancy through mother-to-child transmission via breastfeeding. In less than 5% of infected individuals, a decades-long pathogenic process culminates in the development of ATL. Aggressive subtypes of ATL are life-threatening and challenging to treat, with median overall survival typically less than 1 year in the absence of allogeneic hematopoietic cell transplantation (alloHCT). Owing to the rarity of this illness, prospective large-scale clinical trials have been challenging to perform, and treatment recommendations are largely founded upon limited evidence. Herein, we review the current therapeutic options for ATL, providing a broad literature overview of the foremost clinical trials and reports of this disease. We emphasize our own treatment paradigm, which is broadly based upon disease subtype, patient fitness, and intent to perform alloHCT. Finally, we highlight recent advances in understanding ATL disease biology and important ongoing clinical trials that we foresee as informative and potentially practice-changing.

Genetic Landscape of Peripheral T-Cell Lymphoma

Peripheral T-Cell lymphoma (PTCL) comprises a heterogenous group of uncommon lymphomas derived from mature, post-thymic or “peripheral” T- and natural killer cells. The World Health Organization (WHO) emphasizes a multiparameter approach in the diagnosis and subclassification of these neoplasms, integrating clinical, morphologic, immunophenotypic, and genetic features into the final diagnosis. Clinical presentation is particularly important due to histologic, immunophenotypic and genetic variations within established subtypes, and no convenient immunophenotypic marker of monoclonality exists. In recent years, widespread use of gene expression profiling and next-generation sequencing (NGS) techniques have contributed to an improved understanding of the pathobiology in PTCLs, and these have been incorporated into the 2016 revised WHO classification of mature T- and NK-cell neoplasms which now encompasses nearly 30 distinct entities. This review discusses the genetic landscape of PTCL and its role in subclassification, prognosis, and potential targeted therapy. In addition to discussing T-Cell lymphoma subtypes with relatively well-defined or relevant genetic aberrancies, special attention is given to genetic advances in T-Cell lymphomas of T follicular helper cell (TFH) origin, highlighting genetic overlaps between angioimmunoblastic T-Cell lymphoma (AITL), follicular T-Cell lymphoma, and nodal peripheral T-Cell lymphoma with a TFH phenotype. Furthermore, genetic drivers will be discussed for ALK-negative anaplastic large cell lymphomas and their role in differentiating these from CD30+ peripheral T-Cell lymphoma, not otherwise specified (NOS) and primary cutaneous anaplastic large cell lymphoma. Lastly, a closer look is given to genetic pathways in peripheral T-Cell lymphoma, NOS, which may guide in teasing out more specific entities in a group of T-Cell lymphomas that represents the most common subcategory and is sometimes referred to as a “wastebasket” category.

Triple combination of BET plus PI3K and NF-κB inhibitors exhibit synergistic activity in adult T cell leukemia/lymphoma

Triple combination of I-BET762, copanlisib, and bardoxolone methyl exhibits synergistic activity against ATL in vitro and in vivo.

Triple combination synergizes to inhibit c-MYC ex vivo in PBMCs containing leukemic cells from ATL patients.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell lymphoproliferative malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). ATL is an orphan disease with no curative drug treatment regimens urgently needing new combination therapy. HTLV-1-infected cells rely on viral proteins, Tax and HBZ (HTLV-1-b-ZIP factor), to activate the transcription of various host genes that are critical for promoting leukemic transformation. Inhibition of bromodomain and extraterminal motif (BET) protein was previously shown to collapse the transcriptional network directed by BATF3 super-enhancer and thereby induced ATL cell apoptosis. In the current work, by using xenograft, ex vivo, and in vitro models, we demonstrated that I-BET762 (BETi) synergized with copanlisib (PI3Ki) and bardoxolone methyl (NF-κBi) to dramatically decrease the growth of ATL cells. Mechanistically, the triple combination exhibited synergistic activity by down-regulating the expression of c-MYC while upregulating the level of the glucocorticoid-induced leucine zipper (GILZ). The triple combination also enhanced apoptosis induction by elevating the expression of active caspase-3 and cleaved PARP. Importantly, the triple combination prolonged the survival of ATL-bearing xenograft mice and inhibited the proliferation of ATL cells from peripheral blood mononuclear cells (PBMCs) of both acute and smoldering/chronic ATL patients. Therefore, our data provide the rationale for a clinical trial exploring the multiagent combination of BET, PI3K/AKT, and NF-κB inhibitors for ATL patients and expands the potential treatments for this recalcitrant malignancy.

Recent advances in T-cell lymphoid neoplasms

T Cells comprise many subtypes of specified lymphocytes, and their differentiation and function take place in different tissues. This cellular diversity is also observed in the multiple ways T-cell transformation gives rise to a variety of T-cell neoplasms. This review covers the main types of T-cell malignancies and their specific characteristics, emphasizing recent advances at the cellular and molecular levels as well as differences and commonalities among them.

Emerging Therapeutic Landscape of Peripheral T-Cell Lymphomas Based on Advances in Biology: Current Status and Future Directions

Simple Summary

Peripheral T-cell lymphoma is a rare but aggressive tumor. Due to its rarity, the disease has not been completely understood. In our review, we look at this lymphoma at the molecular level based on available literature. We highlight the mechanism behind the progression and resistance of this tumor. In doing so, we bring forth possible mechanism that could be exploited through novel chemotherapy drugs. In addition, we also look at the current available drugs used in treating this disease, as well as highlight other new drugs, describing their potential in treating this lymphoma. We comprehensively have collected and present the available biology behind peripheral T-cell lymphoma and discuss the available treatment options.

Abstract

T-cell lymphomas are a relatively rare group of malignancies with a diverse range of pathologic features and clinical behaviors. Recent molecular studies have revealed a wide array of different mechanisms that drive the development of these malignancies and may be associated with resistance to therapies. Although widely accepted chemotherapeutic agents and combinations, including stem cell transplantation, obtain responses as initial therapy for these diseases, most patients will develop a relapse, and the median survival is only 5 years. Most patients with relapsed disease succumb within 2 to 3 years. Since 2006, the USFDA has approved five medications for treatment of these diseases, and only anti-CD30-therapy has made a change in these statistics. Clearly, newer agents are needed for treatment of these disorders, and investigators have proposed studies that evaluate agents that target these malignancies and the microenvironment depending upon the molecular mechanisms thought to underlie their pathogenesis. In this review, we discuss the currently known molecular mechanisms driving the development and persistence of these cancers and discuss novel targets for therapy of these diseases and agents that may improve outcomes for these patients.

How I treat adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive T-cell malignancy that arises in a proportion of individuals who are long-term carriers of human T-lymphotropic virus type 1. The median survival of aggressive subtypes is 8 to 10 months; with chemotherapy-based approaches, overall survival has remained largely unchanged in the ∼35 years since ATL was first described. Through the use of 4 representative case studies, we highlight advances in the biological understanding of ATL and the use of novel therapies such as mogamulizumab, as well as how they are best applied to different subtypes of ATL. We discuss the implementation of molecular methods that may guide diagnosis or treatment, although we accept that these are not universally available. In particular, we acknowledge discrepancies in treatment between different countries, reflecting current drug licensing and the difficulties in making treatment decisions in a rare disease, with limited high-quality clinical trial data.

Diagnosis and management of adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell malignancy caused by human T-cell leukemia virus type I (HTLV-1). Between 3% and 5% of HTLV-1-infected individuals develop ATL after a long latency. Confirmation of seropositivity of anti-HTLV-1 antibody, and clonal proliferation of CD4 and CD25 positive lymphocytes with nuclear pleomorphism in patients suspicious of malignant lymphoma or chronic lymphocytic leukemia is crucial for the diagnosis of ATL. The clinical course of ATL is very heterogeneous, and divided into acute, lymphoma, chronic, and smoldering types. The chronic type is further subclassified into the favorable and unfavorable subtypes. Acute, lymphoma, and unfavorable chronic type ATL, and favorable chronic and smoldering type ATL are defined as aggressive and indolent ATL, respectively. Recently identified prognostic indices based on clinical parameters and/or genetic predictors of outcomes need to be confirmed and incorporated for more stratified therapeutic interventions. The standard of care for aggressive ATL is multiagent chemotherapy followed by allogeneic hematopoietic stem cell transplantation if possible, while that for indolent ATL is watchful waiting until progression to aggressive ATL. The combination of interferon-α and zidovudine is also standard for leukemic type ATL. In addition, mogamulizumab, lenalidomide, and brentuximab vedotin have been incorporated into clinical practices in Japan. Furthermore, several novel drugs are currently undergoing clinical trials.

Genomics of Peripheral T-Cell Lymphoma and Its Implications for Personalized Medicine

Peripheral T-cell lymphoma (PTCL) is a rare, heterogenous group of mature T-cell neoplasms that comprise 10–15% of non-Hodgkin lymphoma cases in the United States. All subtypes of PTCL, except for ALK⁺ anaplastic T-cell lymphoma, are associated with poor prognosis, with median overall survival (OS) rates of 1–3 years. The diagnosis of PTCL is mainly based on clinical presentation, morphologic features, and immunophenotypes. Recent advances in genome sequencing and gene expression profiling have given new insights into the pathogenesis and molecular biology of PTCL. An enhanced understanding of its genomic landscape holds the promise of refining the diagnosis, prognosis, and management of PTCL. In this review, we examine recently discovered genetic abnormalities identified by molecular profiling in 3 of the most common types of PTCL: RHOA^G17V and epigenetic regulator mutations in angioimmunoblastic T-cell lymphoma, ALK expression and JAK/STAT3 pathway mutations in anaplastic T-cell lymphoma, and T-follicular helper phenotype and GATA3/TBX21 expression in PTCL-not otherwise specified. We also discuss the implications of these abnormalities for clinical practice, new/potential targeted therapies, and the role of personalized medicine in the management of PTCL.

Unfolded Protein Response in Leukemia: From Basic Understanding to Therapeutic Opportunities

Understanding genetic and epigenetic changes that underlie abnormal proliferation of hematopoietic stem and progenitor cells is critical for development of new approaches to monitor and treat leukemia. The unfolded protein response (UPR) is a conserved adaptive signaling pathway that governs protein folding, secretion, and energy production and serves to maintain protein homeostasis in various cellular compartments. Deregulated UPR signaling, which often occurs in hematopoietic stem cells and leukemia, defines the degree of cellular toxicity and perturbs protein homeostasis, and at the same time, offers a novel therapeutic target. Here, we review current knowledge related to altered UPR signaling in leukemia and highlight possible strategies for exploiting the UPR as treatment for this disease.

Combinatorial ixazomib and belinostat therapy induces NFE2L2-dependent apoptosis in Hodgkin and T-cell lymphoma

Ixazomib activity and transcriptomic analyses previously established in T cell (TCL) and Hodgkin (HL) lymphoma models predicted synergistic activity for histone deacetylase (HDAC) inhibitory combination. In this present study, we determined the mechanistic basis for ixazomib combination with the HDAC inhibitor, belinostat, in HL and TCL cells lines (ixazomib-sensitive/resistant clones) and primary tumour cells. In ixazomib-treated TCL and HL cells, transient inhibition followed by full recovery of proteasomal activity observed was accompanied by induction of proteasomal gene expression with NFE2L2 (also termed NRF2) as a prominent upstream regulator. Downregulation of both NFE2L2 and proteasomal gene expression (validated by quantitative real time polymerase chain reaction) occurred with belinostat treatment in Jurkat and L428 cells. In addition, CRISPR/Cas9 mediated knockdown of NFE2L2 in Jurkat cells resulted in a significant decrease in cell viability with ixazomib compared with untreated control cells. Using transcriptomic and proteasomal activity evaluation of ixazomib, belinostat, or ixazomib + belinostat treated cells, we observed that NFE2L2, proteasome gene expression and functional recovery were abrogated by ixazomib + belinostat combination, resulting in synergistic drug activity in ixazomib-sensitive and -resistant cell lines and primary cells. Altogether, these results suggest that the synergistic activity of ixazomib + belinostat is mediated via inhibition NFE2L2-dependent proteasomal recovery and extended proteasomal inhibition culminating in increased cell death.

Mogamulizumab versus investigator's choice of chemotherapy regimen in relapsed/refractory adult T-cell leukemia/lymphoma

Mogamulizumab, a humanized defucosylated anti-C-C chemokine receptor 4 monoclonal antibody, has been approved in Japan for the treatment of C-C chemokine receptor 4-positive adult T-cell leukemia/lymphoma (ATL). This phase II study evaluated efficacy and safety of mogamulizumab in ATL patients with acute, lymphoma, and chronic subtypes with relapsed/refractory, aggressive disease in the US, Europe, and Latin America. With stratification by subtype, patients were randomized 2:1 to intravenous mogamulizumab 1.0 mg/kg once weekly for 4 weeks and biweekly thereafter (n=47) or investigator's choice of chemotherapy (n=24). The primary end point was confirmed overall response rate (cORR) confirmed on a subsequent assessment at 8 weeks by blinded independent review. ORR was 11% (95%CI: 4-23%) and 0% (95%CI: 0-14%) in the mogamulizumab and chemotherapy arms, respectively. Best response was 28% and 8% in the respective arms. The observed hazard ratio for progression-free survival was 0.71 (95%CI: 0.41-1.21) and, after post hoc adjustment for performance status imbalance, 0.57 (95%CI: 0.337-0.983). The most frequent treatment-related adverse (grade ≥3) events with mogamulizumab were infusion-related reaction and thrombocytopenia (each 9%). Relapsed/refractory ATL is an aggressive, poor prognosis disease with a high unmet need. Investigator's choice chemotherapy did not result in tumor response in this trial; however, mogamulizumab treatment resulted in 11% cORR, with a tolerable safety profile.

(Immuno)proteasomes as therapeutic target in acute leukemia

The clinical efficacy of proteasome inhibitors in the treatment of multiple myeloma has encouraged application of proteasome inhibitor containing therapeutic interventions in (pediatric) acute leukemia. Here, we summarize the positioning of bortezomib, as first-generation proteasome inhibitor, and second-generation proteasome inhibitors in leukemia treatment from a preclinical and clinical perspective. Potential markers for proteasome inhibitor sensitivity and/or resistance emerging from leukemia cell line models and clinical sample studies will be discussed focusing on the role of immunoproteasome and constitutive proteasome (subunit) expression, PSMB5 mutations, and alternative mechanisms of overcoming proteolytic stress.

A Review of New Findings in Adult T-cell Leukemia-Lymphoma: A Focus on Current and Emerging Treatment Strategies

Adult T-cell leukemia–lymphoma (ATL), a rare and aggressive T-cell malignancy caused by human T-cell lymphotropic virus type 1 (HTLV-1), is associated with a poor prognosis. Evidence-based standard treatment options are lacking and outcomes are generally unsatisfactory, particularly for patients with relapsed or refractory disease. Continued research is contributing to changing treatment landscape as a number of existing and investigational agents are evaluated. We describe the epidemiology of HTLV-1 and ATL, discuss the biology behind the disease, review current treatment practices and guidelines, and provide an overview of emerging therapies in ATL, with a focus on those for relapsed or refractory disease.

HTLV-1, the Other Pathogenic Yet Neglected Human Retrovirus: From Transmission to Therapeutic Treatment

Going back to their discovery in the early 1980s, both the Human T-cell Leukemia virus type-1 (HTLV-1) and the Human Immunodeficiency Virus type-1 (HIV-1) greatly fascinated the virology scene, not only because they were the first human retroviruses discovered, but also because they were associated with fatal diseases in the human population. In almost four decades of scientific research, both viruses have had different fates, HTLV-1 being often upstaged by HIV-1. However, although being very close in terms of genome organization, cellular tropism, and viral replication, HIV-1 and HTLV-1 are not completely commutable in terms of treatment, especially because of the opposite fate of the cells they infect: death versus immortalization, respectively. Nowadays, the antiretroviral therapies developed to treat HIV-1 infected individuals and to limit HIV-1 spread among the human population have a poor or no effect on HTLV-1 infected individuals, and thus, do not prevent the development of HTLV-1-associated diseases, which still lack highly efficient treatments. The present review mainly focuses on the course of HTLV-1 infection, from the initial infection of the host to diseases development and associated treatments, but also investigates HIV-1/HTLV-1 co-infection events and their impact on diseases development.

Mogamulizumab for relapsed adult T-cell leukemia-lymphoma: Updated follow-up analysis of phase I and II studies

The present study sought to elucidate the prognosis of adult T-cell leukemia-lymphoma (ATL) patients receiving mogamulizumab, a defucosylated anti-CCR4 monoclonal antibody. Progression-free survival (PFS) and overall survival (OS) of ATL patients enrolled in two studies are herein updated, namely NCT00355472 (phase I study of mogamulizumab in relapsed patients with ATL and peripheral T-cell lymphoma) and NCT00920790 (phase II study for relapsed ATL). Of 13 patients with relapsed aggressive ATL in the phase I study, four (31%) survived >3 years. For 26 relapsed patients with aggressive ATL in the phase II study, median PFS was 5.2 months and 1-year PFS was 26%, whereas median OS was 14.4 months, and 3-year OS was 23%. For patients without a rash or who developed a grade 1 rash only, median PFS was 0.8 months, and 1-year PFS was zero, with a median OS of 6.0 months, and 3-year OS of 8%. In contrast, for patients who developed a rash ≥grade 2, median PFS was 11.7 months, and 1-year PFS was 50%, with a median OS of 25.6 months, and 3-year OS of 36%. Thus, we conclude that mogamulizumab monotherapy may improve PFS and OS in some patients with relapsed aggressive ATL, especially those who develop a skin rash as a moderate immune-related adverse event. Therefore, further investigation is warranted to validate the present observations and to clarify the mechanisms involved in the activity of mogamulizumab.

Molecular basis of targeted therapy in T/NK-cell lymphoma/leukemia: A comprehensive genomic and immunohistochemical analysis of a panel of 33 cell lines

T and NK-cell lymphoma is a collection of aggressive disorders with unfavorable outcome, in which targeted treatments are still at a preliminary phase. To gain deeper insights into the deregulated mechanisms promoting this disease, we searched a panel of 31 representative T-cell and 2 NK-cell lymphoma/leukemia cell lines for predictive markers of response to targeted therapy. To this end, targeted sequencing was performed alongside the expression of specific biomarkers corresponding to potentially activated survival pathways. The study identified TP53, NOTCH1 and DNMT3A as the most frequently mutated genes. We also found common alterations in JAK/STAT and epigenetic pathways. Immunohistochemical analysis showed nuclear accumulation of MYC (in 85% of the cases), NFKB (62%), p-STAT (44%) and p-MAPK (30%). This panel of cell lines captures the complexity of T/NK-cell lymphoproliferative processes samples, with the partial exception of AITL cases. Integrated mutational and immunohistochemical analysis shows that mutational changes cannot fully explain the activation of key survival pathways and the resulting phenotypes. The combined integration of mutational/expression changes forms a useful tool with which new compounds may be assayed.

Multicenter Phase II Study of Lenalidomide in Relapsed or Recurrent Adult T-Cell Leukemia/Lymphoma: ATLL-002

Purpose

Few treatment options exist for adult T-cell leukemia/lymphoma (ATL), and the prognosis for this disease is poor. A phase I study of lenalidomide demonstrated preliminary antitumor activity in patients with relapsed ATL. The current phase II study evaluated the efficacy and safety of lenalidomide monotherapy in patients with relapsed or recurrent ATL.

Patients and Methods

Patients 20 years of age or older with acute, lymphoma, or unfavorable chronic subtype ATL, who had received one or more prior anti-ATL systemic chemotherapy and achieved stable disease or better on their last anti-ATL therapy with subsequent relapse or recurrence, were eligible. Patients received oral lenalidomide 25 mg/d continuously until disease progression or unacceptable toxicity. The primary end point was overall response rate; secondary end points included safety, tumor control rate (stable disease or better), time to response, duration of response, time to progression, progression-free survival, and overall survival.

Results

Objective responses were noted in 11 of 26 patients (overall response rate, 42%; 95% CI, 23% to 63%), including four complete responses and one unconfirmed complete response. The tumor control rate was 73%. The median time to response and duration of response were 1.9 months and not estimable, respectively, and the median time to progression was 3.8 months. The median progression-free survival and overall survival were 3.8 and 20.3 months, respectively. The most frequent grade ≥ 3 adverse events were neutropenia (65%), leukopenia (38%), lymphopenia (38%), and thrombocytopenia (23%), which were all manageable and reversible.

Conclusion

Lenalidomide demonstrated clinically meaningful antitumor activity and an acceptable toxicity profile in patients with relapsed or recurrent aggressive ATL, hinting at its potential to become a treatment option. Further investigations of lenalidomide in ATL and other mature T-cell neoplasms are warranted.

A Multicenter Phase II Study of Twice-Weekly Bortezomib plus Rituximab in Patients with Relapsed Follicular Lymphoma: Long-Term Follow-Up

Single-agent bortezomib (B) has shown activity in heavily pretreated patients with relapsed/refractory indolent lymphoma. On the basis of these findings, we performed a phase II study of B combined with rituximab (R) in patients with relapsed follicular lymphoma (FL). Forty-five patients with fairly good prognostic profiles were enrolled from 2007 to 2011 and received a total of 6 cycles of the B+R combination. The endpoints were the overall response rate (ORR), progression-free survival (PFS), duration of remission (DoR), overall survival (OS), and toxicity evaluation. When considering all the enrolled patients the ORR was 64%. At 5 years, the estimated PFS, DoR, and OS were 34, 49, and 70%, respectively. After excluding the 7 R-naïve patients, the ORR was 58%, with a PFS of 19 months. The most common grade >2 toxicities were thrombocytopenia (18%), peripheral neuropathy (13%), and neutropenia (2%). Our study shows the feasibility, long-term efficacy, and excellent tolerability of the B+R combination. We are aware that our study has specific limitations, such as the small sample size consisting of patients with a relatively good prognostic profile. However, because FL patients will be treated with subsequent chemotherapy regimens, a well-tolerated and effective chemotherapy-free therapy could be considered an additional tool for long-term disease control.

Striving to cure adult T-cell leukaemia/lymphoma: a role for allogeneic stem cell transplant?

Adult T-cell leukaemia/lymphoma (ATL) is an aggressive HTLV-1-related malignancy, rare outside of regions where the retrovirus is endemic. Although the use of antiviral therapy has improved outcomes, particularly for indolent forms of ATL, response to combination chemotherapy is poor and outcomes for aggressive subtypes remains dismal. Consolidation with allogeneic stem cell transplant (alloSCT) has an increasing role in the management of ATL in eligible patients, offering favourable long-term remission rates. However, relatively high-transplant-related mortality and issues with donor recruitment for certain ethnicities remain problematic. In this review, we discuss the rationale for and issues surrounding alloSCT in ATL in the context of conventional and emerging therapies.

Proteasomal Inhibition by Ixazomib Induces CHK1 and MYC-Dependent Cell Death in T-cell and Hodgkin Lymphoma

Proteasome-regulated NF-κB has been shown to be important for cell survival in T-cell lymphoma and Hodgkin lymphoma models. Several new small-molecule proteasome inhibitors are under various stages of active preclinical and clinical development. We completed a comprehensive preclinical examination of the efficacy and associated biologic effects of a second-generation proteasome inhibitor, ixazomib, in T-cell lymphoma and Hodgkin lymphoma cells and in vivo SCID mouse models. We demonstrated that ixazomib induced potent cell death in all cell lines at clinically achievable concentrations. In addition, it significantly inhibited tumor growth and improved survival in T-cell lymphoma and Hodgkin lymphoma human lymphoma xenograft models. Through global transcriptome analyses, proteasomal inhibition showed conserved overlap in downregulation of cell cycle, chromatin modification, and DNA repair processes in ixazomib-sensitive lymphoma cells. The predicted activity for tumor suppressors and oncogenes, the impact on "hallmarks of cancer," and the analysis of key significant genes from global transcriptome analysis for ixazomib strongly favored tumor inhibition via downregulation of MYC and CHK1, its target genes. Furthermore, in ixazomib-treated lymphoma cells, we identified that CHK1 was involved in the regulation of MYC expression through chromatin modification involving histone H3 acetylation via chromatin immunoprecipitation. Finally, using pharmacologic and RNA silencing of CHK1 or the associated MYC-related mechanism, we demonstrated synergistic cell death in combination with antiproteasome therapy. Altogether, ixazomib significantly downregulates MYC and induces potent cell death in T-cell lymphoma and Hodgkin lymphoma, and we identified that combinatorial therapy with anti-CHK1 treatment represents a rational and novel therapeutic approach. Cancer Res; 76(11); 3319-31. ©2016 AACR.

Recent Advances in Therapeutic Approaches for Adult T-cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma caused by human T-cell leukemia/lymphoma virus type 1 (HTLV-1). ATLL occurs in approximately 3%–5% of HTLV-1 carriers during their lifetime and follows a heterogeneous clinical course. The Shimoyama classification has been frequently used for treatment decisions in ATLL patients, and antiviral therapy has been reportedly promising, particularly in patients with indolent type ATLL; however, the prognosis continues to be dismal for patients with aggressive-type ATLL. Recent efforts to improve treatment outcomes have been focused on the development of prognostic stratification and improved dosage, timing, and combination of therapeutic modalities, such as antiviral therapy, chemotherapy, allogeneic hematopoietic stem cell transplantation, and molecular targeted therapy.