Update: peripheral T-cell lymphomas

Cluster Containing More Than 20 CD3-Positive Cells in Bone Marrow Biopsy Is a Candidate Prognostic Indicator in Peripheral T-Cell Lymphoma, Not Otherwise Specified

Assessment of bone marrow (BM) involvement in peripheral T-cell lymphoma, not otherwise specified (PTCL) is straightforward in cases of extensive involvement but difficult in cases of minimal to partial involvement. We evaluated the usefulness of CD3 as an immunohistochemical marker for assessing BM involvement in PTCL patients. BM biopsies of 92 PTCL patients were immunohistochemically stained for CD3, CD4, CD8, CD20, and CD56, and evaluated by two hematopathologists. CD3 positivity was graded according to the proportion of CD3-positive cells and the number of CD3-positive cells in a cluster. These criteria were used to determine the cut-offs at which significant differences in progression-free survival (PFS) and overall survival (OS) were observed. Multivariate analysis controlling the International Prognostic Index (IPI) score and its individual factors revealed that >20 CD3-positive cells in a cluster adversely affected PFS (relative risk [RR], 2.1; 95% confidence interval [CI], 1.0-4.3; P=0.047) and OS (RR, 2.4; 95% CI, 1.1-5.1; P=0.028) independent of IPI score. A cluster with >20 CD3-positive cells is a candidate indicator for BM involvement in PTCL.

Translocation-generated ITK-FER and ITK-SYK fusions induce STAT3 phosphorylation and CD69 expression

Many cancer types carry mutations in protein tyrosine kinase (PTK) and such alterations frequently drive tumor progression. One category is gene translocation of PTKs yielding chimeric proteins with transforming capacity. In this study, we characterized the role of ITK-FER [Interleukin-2-inducible T-cell Kinase (ITK) gene fused with Feline Encephalitis Virus-Related kinase (FER) gene] and ITK-SYK [Interleukin-2-inducible T-cell Kinase (ITK) gene fused with the Spleen Tyrosine Kinase (SYK)] in Peripheral T Cell Lymphoma (PTCL) signaling. We observed an induction of tyrosine phosphorylation events in the presence of both ITK-FER and ITK-SYK. The downstream targets of ITK-FER and ITK-SYK were explored and STAT3 was found to be highly phosphorylated by these fusion kinases. In addition, the CD69 T-cell activation marker was significantly elevated. Apart from tyrosine kinase inhibitors acting directly on the fusions, we believe that drugs acting on downstream targets could serve as alternative cancer therapies for fusion PTKs.

STAT5 inhibition induces TRAIL/DR4 dependent apoptosis in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare, aggressive, heterogeneous, Non-Hodgkin's lymphoma with poor prognosis and inadequate response to current therapies. Recent sequencing studies indicate a prevalence of activating mutations in the JAK/STAT signaling pathway. Oncogenic mutations in STAT5B, observed in approximately one third of cases of multiple different PTCL subtypes, correlate with inferior patient outcomes. Therefore, interest in the development of therapeutic strategies for targeting STAT5 in PTCL is warranted. In this study, we show that the drug pimozide inhibits STAT5 in PTCL, leading to apoptotic cell death by means of the TRAIL/DR4 dependent extrinsic apoptotic pathway. Pimozide induced PTCL cell death is caspase 8 dependent, increases the expression of the TRAIL receptor, DR4, on the surface of pre-apoptotic PTCL cells, and enhances TRAIL induced apoptosis in a TRAIL dependent manner. In parallel, we show that mRNA and protein levels of intrinsic pathway BCL-2 family members and mitochondrial membrane potential remain unaffected by STAT5 knockdown and/or inhibition. In primary PTCL patient samples, pimozide inhibits STAT5 activation and induces apoptosis. Our data support a role for STAT5 inhibition in PTCL and implicate potential utility for inhibition of STAT5 and activation of the extrinsic apoptotic pathway as combination therapy in PTCL.

IRF4/MUM1 expression is associated with poor survival outcomes in patients with peripheral T-cell lymphoma

Background: Interferon regulatory factor 4 (IRF4)/multiple myeloma oncogene-1 (MUM1) is a member of the interferon regulatory factor family of transcriptional factors. Although IRF4/MUM1 expression is associated with aggressiveness of B-cell lymphoma and multiple myeloma, the prognostic value of IRF4/MUM1 expression in peripheral T-cell lymphoma (PTCL) is unclear.

Methods: We analyzed a tissue array from 69 patients diagnosed with PTCL. The expression levels of IRF4/MUM1 and associated proteins such as MYC and Ikaros were analyzed by immunohistochemistry. Samples were classified by IRF4/MUM1 expression into a negative group (less than 5% of all tumor cells staining positive) or a positive group (≥ 5% of all tumor cells staining positive).

Results: IRF4/MUM1 expression was observed in 33% of all patients (23/69), most frequently in patients with anaplastic large cell lymphoma (ALCL, 78%, 7/9). Patients with PTCL, not otherwise specified (PTCL-NOS) and angioimmunoblastic T-cell lymphoma (AITL) showed expression rates of 33% (9/28) and 50% (4/8), respectively, whereas only 3 patients with extranodal NK/T-cell lymphoma (12%, 3/24) showed positive staining. The percentage of IRF4-positive tumor cells was significantly associated with the percentage of MYC-positive tumor cells (R: 0.410, P=0.013). Comparison of survival outcomes revealed that the IRF4/MUM1-positive group exhibited worse survival than the IRF4/MUM1-negative group; moreover, IRF4/MUM1-positive patients with a high level of MYC expression had the worst survival of all patients with nodal PTCL (PTCL-NOS, AITL, and ALCL; n=45) (P < 0.05).

Conclusions: IRF4/MUM1 expression was associated with poor survival outcomes in PTCL, implying that this gene is a potential therapeutic target.

Concurrent Mutations in ATM and Genes Associated with Common γ Chain Signaling in Peripheral T Cell Lymphoma

Peripheral T cell lymphoma (PTCL) is a heterogeneous malignancy with poor response to current therapeutic strategies and incompletely characterized genetics. We conducted whole exome sequencing of matched PTCL and non-malignant samples from 12 patients, spanning 8 subtypes, to identify potential oncogenic mutations in PTCL. Analysis of the mutations identified using computational algorithms, CHASM, PolyPhen2, PROVEAN, and MutationAssessor to predict the impact of these mutations on protein function and PTCL tumorigenesis, revealed 104 somatic mutations that were selected as high impact by all four algorithms. Our analysis identified recurrent somatic missense or nonsense mutations in 70 genes, 9 of which contained mutations predicted significant by all 4 algorithms: ATM, RUNX1T1, WDR17, NTRK3, TP53, TRMT12, CACNA2D1, INTS8, and KCNH8. We observed somatic mutations in ATM (ataxia telangiectasia-mutated) in 5 out of the 12 samples and mutations in the common gamma chain (γc) signaling pathway (JAK3, IL2RG, STAT5B) in 3 samples, all of which also harbored mutations in ATM. Our findings contribute insights into the genetics of PTCL and suggest a relationship between γc signaling and ATM in T cell malignancy.

The oncogenic transcription factor IRF4 is regulated by a novel CD30/NF-κB positive feedback loop in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are generally aggressive non-Hodgkin lymphomas with poor overall survival rates following standard therapy. One-third of PTCLs express interferon regulatory factor-4 (IRF4), a tightly regulated transcription factor involved in lymphocyte growth and differentiation. IRF4 drives tumor growth in several lymphoid malignancies and has been proposed as a candidate therapeutic target. Because direct IRF4 inhibitors are not clinically available, we sought to characterize the mechanism by which IRF4 expression is regulated in PTCLs. We demonstrated that IRF4 is constitutively expressed in PTCL cells and drives Myc expression and proliferation. Using an inhibitor screen, we identified nuclear factor κB (NF-κB) as a candidate regulator of IRF4 expression and cell proliferation. We then demonstrated that the NF-κB subunits p52 and RelB were transcriptional activators of IRF4. Further analysis showed that activation of CD30 promotes p52 and RelB activity and subsequent IRF4 expression. Finally, we showed that IRF4 transcriptionally regulates CD30 expression. Taken together, these data demonstrate a novel positive feedback loop involving CD30, NF-κB, and IRF4; further evidence for this mechanism was demonstrated in human PTCL tissue samples. Accordingly, NF-κB inhibitors may represent a clinical means to disrupt this feedback loop in IRF4-positive PTCLs.

CHO(E)P-14 followed by alemtuzumab consolidation in untreated peripheral T cell lymphomas: final analysis of a prospective phase II trial

The rate of long-term remissions after treatment of peripheral T cell lymphomas (PTCL) with standard CHOP-like protocols is unsatisfactory. A prospective multicenter phase II trial was initiated in untreated patients with PTCL of all International Prognostic Index-risk groups, evaluating alemtuzumab consolidation in patients with complete or good partial remission after CHO(E)P-14 induction. Twenty-nine (70.7 %) of the 41 enrolled patients received alemtuzumab consolidation (133 mg in total). The main grades 3–4 toxicities during alemtuzumab therapy were infections and neutropenia with one potentially treatment-related death. Complete responses were seen in 58.5 %, partial responses in 2.4 % and 29.3 % had progressive disease. After a median observation time of 46 months, 19 patients have died, 16 of them due to lymphoma and/or salvage therapy complications. Event-free and overall survival at 3 years in the whole intent to treat population are 32.3 and 62.5 %, respectively, and 42.4 and 75.1 % in the patients who received alemtuzumab. In conclusion, application of a short course of alemtuzumab after CHO(E)P-14 induction is feasible although complicated by severe infections. A current phase III trial, applying alemtuzumab as part of the initial chemotherapy protocol to avoid early progression, will further clarify its significance for the therapeutic outcome.