Adult T cell leukemia/lymphoma (ATL) is a peripheral T cell neoplasm of largely unknown genetic basis, associated with human T cell leukemia virus type-1 (HTLV-1) infection. Here we describe an integrated molecular study in which we performed whole-genome, exome, transcriptome and targeted resequencing, as well as array-based copy number and methylation analyses, in a total of 426 ATL cases. The identified alterations overlap significantly with the HTLV-1 Tax interactome and are highly enriched for T cell receptor-NF-κB signaling, T cell trafficking and other T cell-related pathways as well as immunosurveillance. Other notable features include a predominance of activating mutations (in PLCG1, PRKCB, CARD11, VAV1, IRF4, FYN, CCR4 and CCR7) and gene fusions (CTLA4-CD28 and ICOS-CD28). We also discovered frequent intragenic deletions involving IKZF2, CARD11 and TP73 and mutations in GATA3, HNRNPA2B1, GPR183, CSNK2A1, CSNK2B and CSNK1A1. Our findings not only provide unique insights into key molecules in T cell signaling but will also guide the development of new diagnostics and therapeutics in this intractable tumor.

Successful treatment of many patients with advanced cancer using antibodies against programmed cell death 1 (PD-1; also known as PDCD1) and its ligand (PD-L1; also known as CD274) has highlighted the critical importance of PD-1/PD-L1-mediated immune escape in cancer development. However, the genetic basis for the immune escape has not been fully elucidated, with the exception of elevated PD-L1 expression by gene amplification and utilization of an ectopic promoter by translocation, as reported in Hodgkin and other B-cell lymphomas, as well as stomach adenocarcinoma. Here we show a unique genetic mechanism of immune escape caused by structural variations (SVs) commonly disrupting the 3' region of the PD-L1 gene. Widely affecting multiple common human cancer types, including adult T-cell leukaemia/lymphoma (27%), diffuse large B-cell lymphoma (8%), and stomach adenocarcinoma (2%), these SVs invariably lead to a marked elevation of aberrant PD-L1 transcripts that are stabilized by truncation of the 3'-untranslated region (UTR). Disruption of the Pd-l1 3'-UTR in mice enables immune evasion of EG7-OVA tumour cells with elevated Pd-l1 expression in vivo, which is effectively inhibited by Pd-1/Pd-l1 blockade, supporting the role of relevant SVs in clonal selection through immune evasion. Our findings not only unmask a novel regulatory mechanism of PD-L1 expression, but also suggest that PD-L1 3'-UTR disruption could serve as a genetic marker to identify cancers that actively evade anti-tumour immunity through PD-L1 overexpression.

Purpose Adult T-cell leukemia-lymphoma (ATL) is a distinct mature T-cell malignancy caused by chronic infection with human T-lymphotropic virus type 1 with diverse clinical features and prognosis. ATL remains a challenging disease as a result of its diverse clinical features, multidrug resistance of malignant cells, frequent large tumor burden, hypercalcemia, and/or frequent opportunistic infection. In 2009, we published a consensus report to define prognostic factors, clinical subclassifications, treatment strategies, and response criteria. The 2009 consensus report has become the standard reference for clinical trials in ATL and a guide for clinical management. Since the last consensus there has been progress in the understanding of the molecular pathophysiology of ATL and risk-adapted treatment approaches. Methods Reflecting these advances, ATL researchers and clinicians joined together at the 18th International Conference on Human Retrovirology—Human T-Lymphotropic Virus and Related Retroviruses—in Tokyo, Japan, March, 2017, to review evidence for current clinical practice and to update the consensus with a new focus on the subtype classification of cutaneous ATL, CNS lesions in aggressive ATL, management of elderly or transplantation-ineligible patients, and treatment strategies that incorporate up-front allogeneic hematopoietic stem-cell transplantation and novel agents. Results As a result of lower-quality clinical evidence, a best practice approach was adopted and consensus statements agreed on by coauthors (> 90% agreement). Conclusion This expert consensus highlights the need for additional clinical trials to develop novel standard therapies for the treatment of ATL

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.

The long-term prognosis of indolent adult T-cell leukemia-lymphoma (ATL) is not clearly elucidated. From 1974 to 2003, newly diagnosed indolent ATL in 90 patients (65 chronic type and 25 smoldering type) was analyzed. The median survival time was 4.1 years; 12 patients remained alive for more than 10 years, 44 progressed to acute ATL, and 63 patients died. The estimated 5-, 10-, and 15-year survival rates were 47.2%, 25.4%, and 14.1%, respectively, with no plateau in the survival curve. Although most patients were treated with watchful waiting, 12 patients were treated with chemotherapy. Kaplan-Meier analyses showed that advanced performance status (PS), neutrophilia, high concentration of lactate dehydrogenase, more than 3 extranodal lesions, more than 4 total involved lesions, and receiving chemotherapy were unfavorable prognostic factors for survival. Multivariate Cox analysis showed that advanced PS was a borderline significant independent factor in poor survival (hazard ratio, 2.1, 95% confidence interval, 1.0-4.6; P ‫؍‬ .06), but it was not a factor when analysis was limited to patients who had not received chemotherapy. The prognosis of indolent ATL in this study was poorer than expected.