IRF4 Mediates the Oncogenic Effects of STAT3 in Anaplastic Large Cell Lymphomas

Systemic anaplastic large cell lymphomas (ALCL) are a category of T-cell non-Hodgkin’s lymphomas which can be divided into anaplastic lymphoma kinase (ALK) positive and ALK negative subgroups, based on ALK gene rearrangements. Among several pathways aberrantly activated in ALCL, the constitutive activation of signal transducer and activator of transcription 3 (STAT3) is shared by all ALK positive ALCL and has been detected in a subgroup of ALK negative ALCL. To discover essential mediators of STAT3 oncogenic activity that may represent feasible targets for ALCL therapies, we combined gene expression profiling analysis and RNA interference functional approaches. A shRNA screening of STAT3-modulated genes identified interferon regulatory factor 4 (IRF4) as a key driver of ALCL cell survival. Accordingly, ectopic IRF4 expression partially rescued STAT3 knock-down effects. Treatment with immunomodulatory drugs (IMiDs) induced IRF4 down regulation and resulted in cell death, a phenotype rescued by IRF4 overexpression. However, the majority of ALCL cell lines were poorly responsive to IMiDs treatment. Combination with JQ1, a bromodomain and extra-terminal (BET) family antagonist known to inhibit MYC and IRF4, increased sensitivity to IMiDs. Overall, these results show that IRF4 is involved in STAT3-oncogenic signaling and its inhibition provides alternative avenues for the design of novel/combination therapies of ALCL

Diffuse large B-cell lymphoma genotyping on the liquid biopsy

Accessible and real-time genotyping for diagnostic, prognostic, or treatment purposes is increasingly impelling in diffuse large B-cell lymphoma (DLBCL). Cell-free DNA (cfDNA) is shed into the blood by tumor cells undergoing apoptosis and can be used as source of tumor DNA for the identification of DLBCL mutations, clonal evolution, and genetic mechanisms of resistance. In this study, we aimed at tracking the basal DLBCL genetic profile and its modification upon treatment using plasma cfDNA. Ultra-deep targeted next generation sequencing of pretreatment plasma cfDNA from DLBCL patients correctly discovered DLBCL-associated mutations that were represented in >20% of the alleles of the tumor biopsy with >90% sensitivity and ∼100% specificity. Plasma cfDNA genotyping also allowed for the recovery of mutations that were undetectable in the tissue biopsy, conceivably because, due to spatial tumor heterogeneity, they were restricted to clones that were anatomically distant from the biopsy site. Longitudinal analysis of plasma samples collected under rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone (R-CHOP) chemotherapy showed a rapid clearance of DLBCL mutations from cfDNA among responding patients. Conversely, among patients who were resistant to R-CHOP, basal DLBCL mutations did not disappear from cfDNA. In addition, among treatment-resistant patients, new mutations were acquired in cfDNA that marked resistant clones selected during the clonal evolution. These results demonstrate that cfDNA genotyping of DLBCL is as accurate as genotyping of the diagnostic biopsy to detect clonally represented somatic tumor mutations and is a real-time and noninvasive approach to tracking clonal evolution and the emergence of treatment-resistant clones

MicroRNA Expression Profiling Identifies Molecular Diagnostic Signatures for Anaplastic Large Cell Lymphoma

Medicine, Research & ExperimentalPathologySCI(E)CPCI-S(ISTP)0MEETING ABSTRACT342A-342A9

Beyond NPM-anaplastic lymphoma kinase driven lymphomagenesis

PURPOSE OF REVIEW: Anaplastic large cell lymphomas (ALCLs) are rare entities whose somatic genetic lesions have been identified only in a subset of patients. Thus, an integrated and massive discovery programme is required to define their tumourigenic alterations and to design more successful tailored therapies. RECENT FINDINGS: The discovery of anaplastic lymphoma kinase (ALK) fusions has provided the basis for the characterization of distinct subsets among ALCL patients. Although the oncogenic addiction of ALK signalling is proven, the tumorigenic contribution of coactivating lesions is still missing. As ALK- and ALK+ share common signatures, it is plausible that analogous mechanisms of transformation may be operating in both subsets, as confirmed by the dysregulated activation of c-MYC, RAS and NF\u3baB, and the loss of Blimp-1 and p53/p63 axis. Nonetheless, recurrent genetic alterations for ALK- ALCL or refractory leukaemic ALK+ ALCL are lacking. Moreover, although conventional chemotherapies (anthracycline-based) are most successful, that is in ALK+ ALCL patients, the implementation of ALK inhibitors or of anti-CD30 based treatments provides innovative solutions, particularly in paediatric ALK+ ALCL and in chemorefractory/relapsed patients. SUMMARY: The complete portrayal of the landscape of genetic alterations in ALCL will dictate the development of innovative chemotherapeutic and targeted therapies that will fit most with the molecular and clinical profiling of individual patients