HELLS regulates transcription in T-cell lymphomas by reducing unscheduled R-loops and by facilitating RNAPII progression.

Chromatin modifiers are emerging as major determinants of many types of cancers, including Anaplastic Large Cell Lymphomas (ALCL), a family of highly heterogeneous T-cell lymphomas for which therapeutic options are still limited. HELLS is a multifunctional chromatin remodeling protein that affects genomic instability by participating in the DNA damage response. Although the transcriptional function of HELLS has been suggested, no clues on how HELLS controls transcription are currently available. In this study, by integrating different multi-omics and functional approaches, we characterized the transcriptional landscape of HELLS in ALCL. We explored the clinical impact of its transcriptional program in a large cohort of 44 patients with ALCL. We demonstrated that HELLS, loaded at the level of intronic regions of target promoters, facilitates RNA Polymerase II (RNAPII) progression along the gene bodies by reducing the persistence of co-transcriptional R-loops and promoting DNA damage resolution. Importantly, selective knockdown of HELLS sensitizes ALCL cells to different chemotherapeutic agents, showing a synergistic effect. Collectively, our work unveils the role of HELLS in acting as a gatekeeper of ALCL genome stability providing a rationale for drug design.

SBNO2 is a critical mediator of STAT3-driven hematological malignancies.

Gain-of-function mutations in the signal transducer and activator of transcription 3 (STAT3) gene are recurrently identified in patients with large granular lymphocytic leukemia (LGLL) and in some cases of natural killer (NK)/T-cell and adult T-cell leukemia/lymphoma. To understand the consequences and molecular mechanisms contributing to disease development and oncogenic transformation, we developed murine hematopoietic stem and progenitor cell models that express mutated STAT3Y640F. These cells show accelerated proliferation and enhanced self-renewal potential. We integrated gene expression analyses and chromatin occupancy profiling of STAT3Y640F-transformed cells with data from patients with T-LGLL. This approach uncovered a conserved set of direct transcriptional targets of STAT3Y640F. Among these, strawberry notch homolog 2 (SBNO2) represents an essential transcriptional target, which was identified by a comparative genome-wide CRISPR/Cas9-based loss-of-function screen. The STAT3-SBNO2 axis is also present in NK-cell leukemia, T-cell non-Hodgkin lymphoma, and NPM-ALK-rearranged T-cell anaplastic large cell lymphoma (T-ALCL), which are driven by STAT3-hyperactivation/mutation. In patients with NPM-ALK+ T-ALCL, high SBNO2 expression correlates with shorter relapse-free and overall survival. Our findings identify SBNO2 as a potential therapeutic intervention site for STAT3-driven hematopoietic malignancies.

Analysis and therapeutic targeting of the IL-1R pathway in anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL), a subgroup of mature T-cell neoplasms with an aggressive clinical course, is characterized by elevated expression of CD30 and anaplastic cytology. To achieve a comprehensive understanding of the molecular characteristics of ALCL pathology and to identify therapeutic vulnerabilities, we applied genome-wide CRISPR library screenings to both anaplastic lymphoma kinase positive (ALK+) and primary cutaneous (pC) ALK- ALCLs and identified an unexpected role of the interleukin-1R (IL-1R) inflammatory pathway in supporting the viability of pC ALK- ALCL. Importantly, this pathway is activated by IL-1α in an autocrine manner, which is essential for the induction and maintenance of protumorigenic inflammatory responses in pC-ALCL cell lines and primary cases. Hyperactivation of the IL-1R pathway is promoted by the A20 loss-of-function mutation in the pC-ALCL lines we analyze and is regulated by the nonproteolytic protein ubiquitination network. Furthermore, the IL-1R pathway promotes JAK-STAT3 signaling activation in ALCLs lacking STAT3 gain-of-function mutation or ALK translocation and enhances the sensitivity of JAK inhibitors in these tumors in vitro and in vivo. Finally, the JAK2/IRAK1 dual inhibitor, pacritinib, exhibited strong activities against pC ALK- ALCL, where the IL-1R pathway is hyperactivated in the cell line and xenograft mouse model. Thus, our studies revealed critical insights into the essential roles of the IL-1R pathway in pC-ALCL and provided opportunities for developing novel therapeutic strategies.

Variant ALK-fusion positive anaplastic large cell lymphoma (ALCL): A population-based paediatric study of the NHL-BFM study group.

Frequency, distribution and prognostic meaning of ALK-partner genes other than NPM1 in ALK-positive anaplastic large-cell lymphoma (ALCL) are unknown. Forty-nine of 316 ALCL diagnosed in the NHL-BFM study group showed no nuclear ALK expression suggestive of a variant ALK-partner; 41 were analysed by genomic capture high-throughput sequencing or specific RT-PCRs. NPM1::ALK was detected in 13 cases. Among the 28 patients with a non-NPM1::ALK-fusion partner, ATIC (n = 8; 29%) and TPM3 (n = 9; 32%) were the most common. Five of eight patients with ATIC::ALK-positive ALCL relapsed, none of nine with TPM3::ALK. Variant ALK-partners are rare and potentially associated with different prognoses.

Peripheral T-cell lymphomas expressing CD30 and CD15 expand the spectrum of anaplastic large cell lymphoma, ALK-negative.

Peripheral T-cell lymphomas (PTCL) are morphologically and biologically heterogeneous and a subset expresses CD30, including anaplastic large cell lymphomas (ALCL) and a minority of PTCL, not otherwise specified (PTCL, NOS). ALCL with ALK translocations (ALCL, ALK+) are readily identified by routine diagnostic methods, but differentiating ALCL without ALK translocation (ALCL, ALK-) and PTCL, NOS expressing CD30 (PTCL CD30+) can be challenging. Furthermore, rare PTCL co-express CD30 and CD15 (PTCL CD30+CD15+); some resemble ALCL, ALK- while others resemble classic Hodgkin lymphoma. To explore the relationship between PTCL CD30+CD15+ and ALCL, ALK-, we analysed 19 cases of PTCL with CD30 expression, previously diagnosed as ALCL, ALK- (nine cases) and PTCL CD30+CD15+ (10 cases) for DUSP22/IRF4 rearrangements, coding RNA expression and selected transcriptome analysis using the NanoString nCounter gene expression analysis platform. Unsupervised clustering showed no clear segregation between ALCL, ALK- and PTCL CD30+CD15+. Three cases previously classified as PTCL CD30+CD15+ showed DUSP22/IRF4 rearrangements, favouring a diagnosis of ALCL, ALK-. Our results suggest that cases previously designated PTCL CD30+CD15+, likely fall within the spectrum of ALCL, ALK-; additionally, a subset of ALCL, ALK- with DUSP22/IRF4 rearrangement expresses CD15, consistent with previous reports and expands the immunophenotypic spectrum of this lymphoma subgroup.

Molecular Screening in Anaplastic Lymphoma Kinase-Positive Anaplastic Large Cell Lymphoma: Anaplastic Lymphoma Kinase Analysis, Next-Generation Sequencing Fusion Gene Detection, and T-Cell Receptor Immunoprofiling.

Anaplastic lymphoma kinase-positive anaplastic large cell lymphoma (ALK+ ALCL) originates from the T-lineage and is marked by rearrangements of the ALK gene. More than 10 fusion partners with the ALK gene are known, with the most common being the t(2;5)(p23;q35) translocation resulting in the NPM1::ALK fusion. In 10% to 20% of the ALK+ ALCL cases, the ALK gene fuses with various other partners. Modern molecular techniques, especially next-generation sequencing (NGS), have eased the identification of ALK gene fusion partners and have allowed in-depth characterization of the T-cell receptor (TCR) repertoire. We devised a real-time quantitative reverse-transcription polymerase chain reaction to measure the expression of the translocated portion of the ALK gene. Fusion partners for the ALK gene were analyzed using rapid amplification of 5'cDNA ends (RACE) method or NGS. TCR immunoprofiling was performed by amplicon NGS. We studied 96 ALK+ ALCL patients. NPM1::ALK fusion gene was observed in 71 patients, ATIC::ALK in 9, and TPM3::ALK in 3. CLTC::ALK, MYH9::ALK, and RNF213::ALK fusions were identified in 2 patients each. We also discovered the TPM4::ALK and SATB1::ALK fusion genes, plus the following 2 previously unidentified ALK+ ALCL fusions: SQSTM1::ALK and CAPRIN1::ALK. High expression of the translocated ALK gene segment was observed in all 93 analyzed samples. TCR testing was conducted on 23 patients with available DNA. In 18 (78%) patients, we discerned at least one (ranging from 1 to 4) clonal TCR rearrangement. In 59% of the patients, clonal TCR beta junctions corresponded with sequences previously observed in both healthy donors and under various pathological conditions. Reverse-transcriptase quantitative detection of ALK expression is a fast and reliable method for both diagnosing and monitoring treatment response in ALK+ ALCL patients, irrespective of the ALK gene translocation. NGS reveals new ALK translocation partners. Both malignant and reactive TCR repertoires in ALK+ ALCL patients are unique and do not consistently occur among different patients.

BIA-ALCL and BIA-SCC: Updates on Clinical Features and Genetic Mutations for Latest Recommendations.

Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL) and Breast Implant-Associated Squamous Cell Carcinoma (BIA-SCC) are emerging neoplastic complications related to breast implants. While BIA-ALCL is often linked to macrotextured implants, current evidence does not suggest an implant-type association for BIA-SCC. Chronic inflammation and genetics have been hypothesized as key pathogenetic players, although for both conditions, the exact mechanisms and specific risks related to breast implants are yet to be established. While the genetic alterations in BIA-SCC are still unknown, JAK-STAT pathway activation has been outlined as a dominant signature of BIA-ALCL. Recent genetic investigation has uncovered various molecular players, including MEK-ERK, PI3K/AKT, CDK4-6, and PDL1. The clinical presentation of BIA-ALCL and BIA-SCC overlaps, including most commonly late seroma and breast swelling, warranting ultrasound and cytological examinations, which are the first recommended steps as part of the diagnostic work-up. While the role of mammography is still limited, MRI and CT-PET are recommended according to the clinical presentation and for disease staging. To date, the mainstay of treatment for BIA-ALCL and BIA-SCC is implant removal with en-bloc capsulectomy. Chemotherapy and radiation therapy have also been used for advanced-stage BIA-ALCL and BIA-SCC. In-depth characterization of the tumor genetics is key for the development of novel therapeutic strategies, especially for advanced stage BIA-ALCL and BIA-SCC, which show a more aggressive course and poor prognosis.

[ALK-positive anaplastic large cell lymphoma of paranasal sinuses: two cases report and literature review]. / ALK-pozitivnaya anaplasticheskaya krupnokletochnaya limfoma s porazheniem pridatochnykh pazukh nosa: dva klinicheskikh nablyudeniya i obzor literatury.

ALK-positive anaplastic large cell lymphoma is a rare T-cell lymphoma with ALK gene rearrangement that develops in children and young adults. The disease almost always affects the lymph nodes, and extranodal areas are also frequently involved. This article describes two cases of atypical localization of ALK-positive anaplastic large cell lymphoma with involvement of the paranasal sinuses.

Brentuximab vedotin in combination with chemotherapy for pediatric patients with ALK+ ALCL: results of COG trial ANHL12P1.

Approximately 30% of pediatric patients with anaplastic large cell lymphoma (ALCL) relapse. Although brentuximab vedotin has demonstrated excellent activity in ALCL, it has not been used for newly diagnosed patients. Children's Oncology Group (COG) trial ANHL12P1 determined the toxicity and efficacy of brentuximab vedotin with chemotherapy in children with newly diagnosed nonlocalized anaplastic large cell lymphoma kinase (ALK)+/CD30+ ALCL. From 2013 to 2017, 68 children with ALK+ ALCL were enrolled and received brentuximab vedotin. All patients received 5-day prophase, followed by 6 cycles of chemotherapy. Brentuximab vedotin was given on day 1 of each of the 6 cycles. Of the 67 patients eligible for toxicity evaluation, 66 completed all 6 cycles of chemotherapy, resulting in 399 evaluable cycles. There were no toxic deaths, no case of progressive multifocal leukoencephalopathy syndrome, and no case of grade 3 or 4 neuropathy. The 2-year event-free survival (EFS) was 79.1% (95% confidence interval [CI], 67.2-87.1). The 2-year overall survival (OS) was 97.0% (95% CI, 88.1-99.2). Fourteen patients relapsed. Eleven of 14 (79%) relapses occurred within 10 months of diagnosis; only 1 patient (1.5%) relapsed during therapy. Quantitative reverse transcription polymerase chain reaction for NPM-ALK at baseline (minimal disseminated disease) demonstrated prognostic value for EFS (P = .0004). Overall, the addition of brentuximab vedotin to standard chemotherapy does not add significant toxicity or alter the desired interval between cycles. The addition of brentuximab vedotin prevented relapses during therapy, and the OS and EFS estimates compare favorably with results obtained using conventional chemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT01979536.

Pathobiology of nodal peripheral T-cell lymphomas: current understanding and future directions.

Predominantly nodal is the most common clinical presentation of peripheral T- (and NK-) cell lymphomas (PTCL), which comprise three main groups of diseases: (i) systemic anaplastic large cell lymphomas (ALCL), whether positive or negative for anaplastic lymphoma kinase (ALK); (ii) follicular helper T-cell lymphomas (TFHL); and (iii) PTCL, not otherwise specified (NOS). Recent advances in the genomic and molecular characterization of PTCL, with enhanced understanding of pathobiology, have translated into significant updates in the latest 2022 classifications of lymphomas. ALK-negative ALCL is now recognized to be genetically heterogeneous, with identification of DUSP22 rearrangements in approximately 20-30% of cases, correlated with distinctive pathological and biological features. The notion of cell-of-origin as an important determinant of the classification of nodal PTCL is best exemplified by TFHL, considered as one disease or a group of related entities, sharing oncogenic pathways with frequent recurrent epigenetic mutations as well as a relationship to clonal hematopoiesis. Data are emerging to support that a similar cell-of-origin concept might be relevant to characterize meaningful subgroups within PTCL, NOS, based on cytotoxic and/or Th1 versus Th2 signatures. The small group of primary nodal Epstein-Barr virus-positive lymphomas of T- or NK-cell derivation, formerly considered PTCL, NOS, is now classified separately, due to distinctive features, and notably an aggressive course. This review summarizes current knowledge of the pathology and biology of nodal-based PTCL entities, with an emphasis on recent findings and underlying oncogenic mechanisms.

ALK-negative anaplastic large cell lymphoma with DUSP22 rearrangement has distinctive disease characteristics with better progression-free survival: a LYSA study.

ALK-negative anaplastic large cell lymphoma (ALCL) comprises subgroups harboring rearrangements of DUSP22 (DUSP22- R) or TP63 (TP63-R). Two studies reported 90% and 40% 5-year overall survival (OS) rates in 21 and 12 DUSP22-R/TP63- not rearranged (NR) patients, respectively, making the prognostic impact of DUSP22-R unclear. Here, 104 newly diagnosed ALK-negative ALCL patients (including 37 from first-line clinical trials) from the LYSA TENOMIC database were analyzed by break-apart fluorescence in situ hybridization assays for DUSP22-R and TP63-R. There were 47/104 (45%) DUSP22-R and 2/93 (2%) TP63-R cases, including one DUSP22-R/TP63-R case. DUSP22-R tumors more frequently showed CD3 expression (62% vs. 35%, P=0.01), and less commonly a cytotoxic phenotype (27% vs. 82%; P<0.001). At diagnosis, DUSP22- R ALCL patients more frequently had bone involvement (32% vs. 13%, P=0.03). The patient with DUSP22-R/TP63-R ALCL had a rapidly fatal outcome. After a median follow-up of 4.9 years, 5-year progression-free survival (PFS) and OS rates of 84 patients without TP63-R treated with curative-intent anthracycline-based chemotherapy were 41% and 53%, respectively. According to DUSP22 status, 5-year PFS was 57% for 39 DUSP22-R versus 26% for 45 triple-negative (DUSP22-NR/TP63-NR/ALK-negative) patients (P=0.001). The corresponding 5-year OS rates were 65% and 41%, respectively (P=0.07). In multivariate analysis, performance status and DUSP22 status significantly affected PFS, and distinguished four risk groups, with 4-year PFS and OS ranging from 17% to 73% and 21% to 77%, respectively. Performance status but not DUSP22 status influenced OS. The use of brentuximab vedotin in relapsed/refractory patients improved OS independently of DUSP22 status. Our findings support the biological and clinical distinctiveness of DUSP22- R ALK-negative ALCL. Its relevance to outcome in patients receiving frontline brentuximab vedotin remains to be determined.

Prognostic factors for primary cutaneous anaplastic large-cell lymphoma: a multicentre retrospective study from Japan.

BACKGROUND: The clinical implications of DUSP22 rearrangement and the association between DUSP22 rearrangement and lymphoid enhancer-binding factor 1 (LEF1) expression pattern in CD30+ cutaneous T-cell lymphomas (CTCLs) are unknown. OBJECTIVES: This study assessed the incidence of DUSP22 rearrangement and its clinical and immunohistochemical implications in primary cutaneous anaplastic large-cell lymphoma (pcALCL), lymphomatoid papulosis (LyP) and CD30+ mycosis fungoides with large-cell transformation (MF-LCT), focusing especially on the association with the prognosis and LEF1 expression pattern. Prognostic factors of pcALCL were also examined. METHODS: We conducted a multicentre retrospective study including patients with pcALCL, LyP and MF-LCT diagnosed between 1 January 2000 and 31 December 2018 in Japan. Baseline data at diagnosis, treatment course, overall survival (OS) and disease-specific survival (DSS) were collected. Immunohistochemical analysis and fluorescence in situ hybridization to detect DUSP22 and TP63 rearrangement were performed using skin samples at diagnosis. We investigated the association between staining pattern and these gene rearrangements. We also assessed the prognostic implications of clinical status, immunohistochemical results and the presence of gene rearrangements. RESULTS: DUSP22 rearrangement was detected in 50% (11 of 22) of cases of pcALCL, but not in any cases with LyP (0 of 14) or MF-LCT (0 of 11). TP63 rearrangement was not detected in any case. Clinically, patients with pcALCL with DUSP22 rearrangement did not tend to develop ulcers (P = 0.081). There was no significant association between DUSP22 rearrangement status and immunohistochemical results, including LEF1 expression pattern. T3 stage and the presence of lower limb lesions were significantly associated with shorter OS (P = 0.012 and 0.021, respectively, by log-rank test). Similarly, they were significantly correlated with shorter DSS (P = 0.016 and 0.0001, respectively). CONCLUSIONS: DUSP22 rearrangement is relatively specific to pcALCL among CD30+ CTCLs in Japan. Although the LEF1 expression pattern was not related to DUSP22 rearrangement in pcALCL, there was no rearrangement if LEF1 was not expressed. We confirmed that T3 stage and the lower limb involvement were significantly associated with decreased OS and DSS. The presence or absence of lower limb lesions should be included in T-stage subcategorization in the future.

The Role of IgM Antibodies in T Cell Lymphoma Protection in a Novel Model Resembling Anaplastic Large Cell Lymphoma.

MRL/lpr mice typically succumb to immune complex-mediated nephritis within the first year of life. However, MRL/lpr mice that only secrete IgM Abs because of activation-induced deaminase deficiency (AID-/-MRL/lpr mice) experienced a dramatic increase in survival. Further crossing of these mice to those incapable of making secretory IgM (µS mice) generated mice lacking any secreted Abs but with normal B cell receptors. Both strains revealed no kidney pathology, yet Ab-deficient mice still experienced high mortality. In this article, we report Ab-deficient MRL/lpr mice progressed to high-grade T cell lymphoma that can be reversed with injection of autoreactive IgM Abs or following adoptive transfer of IgM-secreting MRL/lpr B cells. Anti-nuclear Abs, particularly anti-dsDNA IgM Abs, exhibited tumor-killing activities against a murine T cell lymphoma cell line. Passive transfers of autoreactive IgM Abs into p53-deficient mice increased survival by delaying onset of T cell lymphoma. The lymphoma originated from a double-negative aberrant T cell population seen in MRL/lpr mice and most closely resembled human anaplastic large cell lymphoma. Combined, these results strongly implicate autoreactive IgM Abs in protection against T cell lymphoma.

Nuclear NPM-ALK Protects Myc from Proteasomal Degradation and Contributes to Its High Expression in Cancer Stem-Like Cells in ALK-Positive Anaplastic Large Cell Lymphoma.

In ALK-positive anaplastic large cell lymphoma (ALK+ALCL), a small subset of cancer stem-like (or RR) cells characterized by high Myc expression have been identified. We hypothesize that NPM-ALK contributes to their high Myc expression. While transfection of NPM-ALK into HEK293 cells effectively increased Myc by inhibiting its proteosomal degradation (PD-Myc), this effect was dramatically attenuated when the full-length NPM1 (FL-NPM1) was downregulated using shRNA, highlighting the importance of the NPM-ALK:FL-ALK heterodimers in this context. Consistent with this concept, immunoprecipitation experiments showed that the heterodimers are abundant only in RR cells, in which the half-life of Myc is substantially longer than the bulk cells. Fbw7γ, a key player in PD-Myc, is sequestered by the heterodimers in RR cells, and this finding correlates with a Myc phosphorylation pattern indicative of ineffective PD-Myc. Using confocal microscopy and immunofluorescence staining, we found that the fusion signal between ALK and FL-NPM1, characteristic of the heterodimers, correlates with the Myc level in ALK+ALCL cells from cell lines and patient samples. To conclude, our findings have revealed a novel oncogenic function of NPM-ALK in the nucleus. Specifically, the NPM-ALK:FL-NPM1 heterodimers increase cancer stemness by blocking PD-Myc and promoting Myc accumulation in the cancer stem-like cell subset.

De novo generation of the NPM-ALK fusion recapitulates the pleiotropic phenotypes of ALK+ ALCL pathogenesis and reveals the ROR2 receptor as target for tumor cells.

BACKGROUND: Anaplastic large cell lymphoma positive for ALK (ALK+ ALCL) is a rare type of non-Hodgkin lymphoma. This lymphoma is caused by chromosomal translocations involving the anaplastic lymphoma kinase gene (ALK). In this study, we aimed to identify mechanisms of transformation and therapeutic targets by generating a model of ALK+ ALCL lymphomagenesis ab initio with the specific NPM-ALK fusion. METHODS: We performed CRISPR/Cas9-mediated genome editing of the NPM-ALK chromosomal translocation in primary human activated T lymphocytes. RESULTS: Both CD4+ and CD8+ NPM-ALK-edited T lymphocytes showed rapid and reproducible competitive advantage in culture and led to in vivo disease development with nodal and extra-nodal features. Murine tumors displayed the phenotypic diversity observed in ALK+ ALCL patients, including CD4+ and CD8+ lymphomas. Assessment of transcriptome data from models and patients revealed global activation of the WNT signaling pathway, including both canonical and non-canonical pathways, during ALK+ ALCL lymphomagenesis. Specifically, we found that the WNT signaling cell surface receptor ROR2 represented a robust and genuine marker of all ALK+ ALCL patient tumor samples. CONCLUSIONS: In this study, ab initio modeling of the ALK+ ALCL chromosomal translocation in mature T lymphocytes enabled the identification of new therapeutic targets. As ROR2 targeting approaches for other cancers are under development (including lung and ovarian tumors), our findings suggest that ALK+ ALCL cases with resistance to current therapies may also benefit from ROR2 targeting strategies.

PDGFRß promotes oncogenic progression via STAT3/STAT5 hyperactivation in anaplastic large cell lymphoma.

BACKGROUND: Anaplastic large cell lymphoma (ALCL) is an aggressive non-Hodgkin T cell lymphoma commonly driven by NPM-ALK. AP-1 transcription factors, cJUN and JUNb, act as downstream effectors of NPM-ALK and transcriptionally regulate PDGFRß. Blocking PDGFRß kinase activity with imatinib effectively reduces tumor burden and prolongs survival, although the downstream molecular mechanisms remain elusive. METHODS AND RESULTS: In a transgenic mouse model that mimics PDGFRß-driven human ALCL in vivo, we identify PDGFRß as a driver of aggressive tumor growth. Mechanistically, PDGFRß induces the pro-survival factor Bcl-xL and the growth-enhancing cytokine IL-10 via STAT5 activation. CRISPR/Cas9 deletion of both STAT5 gene products, STAT5A and STAT5B, results in the significant impairment of cell viability compared to deletion of STAT5A, STAT5B or STAT3 alone. Moreover, combined blockade of STAT3/5 activity with a selective SH2 domain inhibitor, AC-4-130, effectively obstructs tumor development in vivo. CONCLUSIONS: We therefore propose PDGFRß as a novel biomarker and introduce PDGFRß-STAT3/5 signaling as an important axis in aggressive ALCL. Furthermore, we suggest that inhibition of PDGFRß or STAT3/5 improve existing therapies for both previously untreated and relapsed/refractory ALK+ ALCL patients.

Small cell/lymphohistiocytic morphology is associated with peripheral blood involvement, CD8 positivity and retained T-cell antigens, but not outcome in adults with ALK+ anaplastic large cell lymphoma.

Several morphologic variants of ALK+ anaplastic large cell lymphoma (ALCL) are recognized. The small cell (SC) and lymphohistiocytic (LH) variants are reported to be associated with poorer outcome in children with ALK + ALCL. In this study of 102 adults with ALK + ALCL, there were 18 (18%) cases of SC and/or LH variants. Patients with SC/LH ALK + ALCL more often had peripheral blood involvement than patients with non-SC/LH neoplasms (60% vs 0%, p = 0.02). There were no other significant differences in clinical features between patients with SC/LH versus non-SC/LH ALK + ALCL. Compared with non-SC/LH cases of ALK + ALCL, neoplasms with SC/LH features were more often positive for CD2 (92% vs. 36%, p = 0.0007), CD3 (81% vs. 15%, p = 0.0001), CD7 (80% vs. 37%, p = 0.03), and CD8 (54% vs. 7%, p = 0.0006). There were no other significant differences in the immunophenotype between SC/LH and non-SC/LH ALK + ALCL cases. The initial chemotherapy regimens and the response rates were similar between patients with ALK + ALCL with SC/LH patterns versus those with non-SC/LH patterns. After a median follow-up of 30.8 months (range, 0.3-208 months), patients with high (>3) International Prognostic Index (IPI) scores had significantly shorter overall survival than patients with low (<3) IPI scores (p = 0.003). However, there was no significant difference in overall or progression-free survival between patients with SC/LH versus non-SC/LH ALK + ALCL (p = 0.99 and p = 0.94, respectively). We conclude that, in adults with ALK + ALCL, SC and LH variants are associated with peripheral blood involvement and a CD8 + immunophenotype with retention of T-cell markers (CD2, CD3, and CD7). However, in contrast with children with ALK + ALCL, SC and LH variants appear to have no impact on prognosis in adults with ALK + ALCL.

Gene alterations in epigenetic modifiers and JAK-STAT signaling are frequent in breast implant-associated ALCL.

The oncogenic events involved in breast implant-associated anaplastic large cell lymphoma (BI-ALCL) remain elusive. To clarify this point, we have characterized the genomic landscape of 34 BI-ALCLs (15 tumor and 19 in situ subtypes) collected from 54 BI-ALCL patients diagnosed through the French Lymphopath network. Whole-exome sequencing (n = 22, with paired tumor/germline DNA) and/or targeted deep sequencing (n = 24) showed recurrent mutations of epigenetic modifiers in 74% of cases, involving notably KMT2C (26%), KMT2D (9%), CHD2 (15%), and CREBBP (15%). KMT2D and KMT2C mutations correlated with a loss of H3K4 mono- and trimethylation by immunohistochemistry. Twenty cases (59%) showed mutations in ≥1 member of the JAK/STAT pathway, including STAT3 (38%), JAK1 (18%), and STAT5B (3%), and in negative regulators, including SOCS3 (6%), SOCS1 (3%), and PTPN1 (3%). These mutations were more frequent in tumor-type samples than in situ samples (P = .038). All BI-ALCLs expressed pSTAT3, regardless of the mutational status of genes in the JAK/STAT pathway. Mutations in the EOMES gene (12%) involved in lymphocyte development, PI3K-AKT/mTOR (6%), and loss-of-function mutations in TP53 (12%) were also identified. Copy-number aberration (CNA) analysis identified recurrent alterations, including gains on chromosomes 2, 9p, 12p, and 21 and losses on 4q, 8p, 15, 16, and 20. Regions of CNA encompassed genes involved in the JAK/STAT pathway and epigenetic regulators. Our results show that the BI-ALCL genomic landscape is characterized by not only JAK/STAT activating mutations but also loss-of-function alterations of epigenetic modifiers.

Chromosome 20 loss is characteristic of breast implant-associated anaplastic large cell lymphoma.

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a very rare type of T-cell lymphoma that is uniquely caused by a single environmental stimulus. Here, we present a comprehensive genetic analysis of a relatively large series of BIA-ALCL (n = 29), for which genome-wide chromosomal copy number aberrations (CNAs) and mutational profiles for a subset (n = 7) were determined. For comparison, CNAs for anaplastic lymphoma kinase (ALK)- nodal anaplastic large cell lymphomas (ALCLs; n = 24) were obtained. CNAs were detected in 94% of BIA-ALCLs, with losses at chromosome 20q13.13 in 66% of the samples. Loss of 20q13.13 is characteristic of BIA-ALCL compared with other classes of ALCL, such as primary cutaneous ALCL and systemic type ALK+ and ALK- ALCL. Mutational patterns confirm that the interleukin-6-JAK1-STAT3 pathway is deregulated. Although this is commonly observed across various types of T-cell lymphomas, the extent of deregulation is significantly higher in BIA-ALCL, as indicated by phosphorylated STAT3 immunohistochemistry. The characteristic loss of chromosome 20 in BIA-ALCL provides further justification to recognize BIA-ALCL as a separate disease entity. Moreover, CNA analysis may serve as a parameter for future diagnostic assays for women with breast implants to distinguish seroma caused by BIA-ALCL from other causes of seroma accumulation, such as infection or trauma.

IL10RA modulates crizotinib sensitivity in NPM1-ALK+ anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL) is a T-cell malignancy predominantly driven by a hyperactive anaplastic lymphoma kinase (ALK) fusion protein. ALK inhibitors, such as crizotinib, provide alternatives to standard chemotherapy with reduced toxicity and side effects. Children with lymphomas driven by nucleophosmin 1 (NPM1)-ALK fusion proteins achieved an objective response rate to ALK inhibition therapy of 54% to 90% in clinical trials; however, a subset of patients progressed within the first 3 months of treatment. The mechanism for the development of ALK inhibitor resistance is unknown. Through genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) activation and knockout screens in ALCL cell lines, combined with RNA sequencing data derived from ALK inhibitor-relapsed patient tumors, we show that resistance to ALK inhibition by crizotinib in ALCL can be driven by aberrant upregulation of interleukin 10 receptor subunit alpha (IL10RA). Elevated IL10RA expression rewires the STAT3 signaling pathway, bypassing otherwise critical phosphorylation by NPM1-ALK. IL-10RA expression does not correlate with response to standard chemotherapy in pediatric patients, suggesting that a combination of crizotinib and chemotherapy could prevent ALK inhibitor resistance-specific relapse.