CDK4/6 inhibition augments anti-tumor efficacy of XPO1 inhibitor selinexor in natural killer/T-cell lymphoma.

XPO1 is an attractive and promising therapeutic target frequently overexpressed in multiple hematological malignancies. The clinical use of XPO1 inhibitors in natural killer/T-cell lymphoma (NKTL) is not well documented. Here, we demonstrated that XPO1 overexpression is an indicator of poor prognosis in patients with NKTL. The compassionate use of the XPO1 inhibitor selinexor in combination with chemotherapy showed favorable clinical outcomes in three refractory/relapsed (R/R) NKTL patients. Selinexor induced complete tumor regression and prolonged survival in sensitive xenografts but not in resistant xenografts. Transcriptomic profiling analysis indicated that sensitivity to selinexor was correlated with deregulation of the cell cycle machinery, as selinexor significantly suppressed the expression of cell cycle-related genes. CDK4/6 inhibitors were identified as sensitizers that reversed selinexor resistance. Mechanistically, targeting CDK4/6 could enhance the anti-tumor efficacy of selinexor via the suppression of CDK4/6-pRb-E2F-c-Myc pathway in resistant cells, while selinexor alone could dramatically block this pathway in sensitive cells. Overall, our study provids a preclinical proof-of-concept for the use of selinexor alone or in combination with CDK4/6 inhibitors as a novel therapeutic strategy for patients with R/R NKTL.

Single-cell landscape of idiopathic multicentric Castleman disease in identical twins.

ABSTRACT: Idiopathic multicentric Castleman disease (iMCD) is a rare cytokine-driven disorder characterized by systemic inflammation, generalized lymphadenopathy, and organ dysfunction. Here, we present an unusual occurrence of iMCD in identical twins and examined the immune milieu within the affected lymphoid organs and the host circulation using multiomic high-dimensional profiling. Using spatial enhanced resolution omics sequencing (Stereo-seq) transcriptomic profiling, we performed unsupervised spatially constrained clustering to identify different anatomic structures, mapping the follicles and interfollicular regions. After a cell segmentation approach, interleukin 6 (IL-6) pathway genes significantly colocalized with endothelial cells and fibroblastic reticular cells, confirming observations using a single-cell sequencing approach (10× Chromium). Furthermore, single-cell sequencing of peripheral blood mononuclear cells revealed an "inflammatory" peripheral monocytosis enriched for the expression of S100A family genes in both twins. In summary, we provided evidence of the putative cell-of-origin of IL-6 signals in iMCD and described a distinct monocytic host immune response phenotype through a unique identical twin model.

ASTER: A Method to Predict Clinically Relevant Synthetic Lethal Genetic Interactions.

A Synthetic Lethal (SL) interaction is a functional relationship between two genes or functional entities where the loss of either entity is viable but the loss of both is lethal. Such pairs can be used to develop targeted anticancer therapies with fewer side effects and reduced overtreatment. However, finding clinically relevant SL interactions remains challenging. Leveraging unified gene expression data of both disease-free and cancerous samples, we design a new technique based on statistical hypothesis testing, called ASTER, to identify SL pairs. We empirically find that the patterns of mutually exclusivity ASTER finds using genomic and transcriptomic data provides a strong signal of synthetic lethality. For large-scale multiple hypothesis testing, we develop an extension called ASTER++ that can utilize additional input gene features within the hypothesis testing framework. Our computational and functional experiments demonstrate the efficacy of ASTER in identifying SL pairs with potential therapeutic benefits.

Single-Cell Analysis Reveals Malignant Cells Reshape the Cellular Landscape and Foster an Immunosuppressive Microenvironment of Extranodal NK/T-Cell Lymphoma.

Extranodal natural killer/T-cell lymphoma (NKTCL) is an aggressive type of lymphoma associated with Epstein-Barr virus (EBV) and characterized by heterogeneous tumor behaviors. To better understand the origins of the heterogeneity, this study utilizes single-cell RNA sequencing (scRNA-seq) analysis to profile the tumor microenvironment (TME) of NKTCL at the single-cell level. Together with in vitro and in vivo models, the study identifies a subset of LMP1+ malignant NK cells contributing to the tumorigenesis and development of heterogeneous malignant cells in NKTCL. Furthermore, malignant NK cells interact with various immunocytes via chemokines and their receptors, secrete substantial DPP4 that impairs the chemotaxis of immunocytes and regulates their infiltration. They also exhibit an immunosuppressive effect on T cells, which is further boosted by LMP1. Moreover, high transcription of EBV-encoded genes and low infiltration of tumor-associated macrophages (TAMs) are favorable prognostic indicators for NKTCL in multiple patient cohorts. This study for the first time deciphers the heterogeneous composition of NKTCL TME at single-cell resolution, highlighting the crucial role of malignant NK cells with EBV-encoded LMP1 in reshaping the cellular landscape and fostering an immunosuppressive microenvironment. These findings provide insights into understanding the pathogenic mechanisms of NKTCL and developing novel therapeutic strategies against NKTCL.

Clinical features and prognostic outcomes of angioimmunoblastic T cell lymphoma in an Asian multicenter study.

In our Asian multicenter retrospective study, we investigated the clinical prognostic factors affecting the outcomes of AITL patients and identified a novel prognostic index relevant in the Asian context. In our 174-patient cohort, the median PFS and OS was 1.8 years and 5.6 years respectively. Age > 60, bone marrow involvement, total white cell count >12 × 109/L and raised serum lactate dehydrogenase were associated with poorer PFS and OS in multivariate analyses. This allowed for a prognostic index (AITL-PI) differentiating patients into low (0-1 factors, n = 64), moderate (2 factors, n = 59) and high-risk (3-4 factors, n = 49) subgroups with 5-year OS of 84.0%, 44.0% and 28.0% respectively (p < 0.0001). POD24 proved to be strongly prognostic (5-year OS 24% vs 89%, p < 0.0001). Exploratory gene expression studies were performed and disparate immune cell profiles and cell signaling signatures were seen in the low risk group as compared to the intermediate and high risk groups.

PBRM1-deficient PBAF complexes target aberrant genomic loci to activate the NF-κB pathway in clear cell renal cell carcinoma.

PBRM1 encodes an accessory subunit of the PBAF SWI/SNF chromatin remodeller, and the inactivation of PBRM1 is a frequent event in kidney cancer. However, the impact of PBRM1 loss on chromatin remodelling is not well examined. Here we show that, in VHL-deficient renal tumours, PBRM1 deficiency results in ectopic PBAF complexes that localize to de novo genomic loci, activating the pro-tumourigenic NF-κB pathway. PBRM1-deficient PBAF complexes retain the association between SMARCA4 and ARID2, but have loosely tethered BRD7. The PBAF complexes redistribute from promoter proximal regions to distal enhancers containing NF-κB motifs, heightening NF-κB activity in PBRM1-deficient models and clinical samples. The ATPase function of SMARCA4 maintains chromatin occupancy of pre-existing and newly acquired RELA specific to PBRM1 loss, activating downstream target gene expression. Proteasome inhibitor bortezomib abrogates RELA occupancy, suppresses NF-κB activation and delays growth of PBRM1-deficient tumours. In conclusion, PBRM1 safeguards the chromatin by repressing aberrant liberation of pro-tumourigenic NF-κB target genes by residual PBRM1-deficient PBAF complexes.

Aberrant JAK-STAT signaling-mediated chromatin remodeling impairs the sensitivity of NK/T-cell lymphoma to chidamide.

BACKGROUND: Natural killer/T-cell lymphoma (NKTL) is a rare type of aggressive and heterogeneous non-Hodgkin's lymphoma (NHL) with a poor prognosis and limited therapeutic options. Therefore, there is an urgent need to exploit potential novel therapeutic targets for the treatment of NKTL. Histone deacetylase (HDAC) inhibitor chidamide was recently approved for treating relapsed/refractory peripheral T-cell lymphoma (PTCL) patients. However, its therapeutic efficacy in NKTL remains unclear. METHODS: We performed a phase II clinical trial to evaluate the efficacy of chidamide in 28 relapsed/refractory NKTL patients. Integrative transcriptomic, chromatin profiling analysis and functional studies were performed to identify potential predictive biomarkers and unravel the mechanisms of resistance to chidamide. Immunohistochemistry (IHC) was used to validate the predictive biomarkers in tumors from the clinical trial. RESULTS: We demonstrated that chidamide is effective in treating relapsed/refractory NKTL patients, achieving an overall response and complete response rate of 39 and 18%, respectively. In vitro studies showed that hyperactivity of JAK-STAT signaling in NKTL cell lines was associated with the resistance to chidamide. Mechanistically, our results revealed that aberrant JAK-STAT signaling remodels the chromatin and confers resistance to chidamide. Subsequently, inhibition of JAK-STAT activity could overcome resistance to chidamide by reprogramming the chromatin from a resistant to sensitive state, leading to synergistic anti-tumor effect in vitro and in vivo. More importantly, our clinical data demonstrated that combinatorial therapy with chidamide and JAK inhibitor ruxolitinib is effective against chidamide-resistant NKTL. In addition, we identified TNFRSF8 (CD30), a downstream target of the JAK-STAT pathway, as a potential biomarker that could predict NKTL sensitivity to chidamide. CONCLUSIONS: Our study suggests that chidamide, in combination with JAK-STAT inhibitors, can be a novel targeted therapy in the standard of care for NKTL. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02878278. Registered 25 August 2016, https://clinicaltrials.gov/ct2/show/NCT02878278.

Emerging predictive biomarkers for novel therapeutics in peripheral T-cell and natural killer/T-cell lymphoma.

Peripheral T-cell lymphoma (PTCL) and natural killer/T-cell lymphoma (NKTCL) are rare subtypes of non-Hodgkin's lymphoma that are typically associated with poor treatment outcomes. Contemporary first-line treatment strategies generally involve the use of combination chemoimmunotherapy, radiation and/or stem cell transplant. Salvage options incorporate a number of novel agents including epigenetic therapies (e.g. HDAC inhibitors, DNMT inhibitors) as well as immune checkpoint inhibitors. However, validated biomarkers to select patients for individualized precision therapy are presently lacking, resulting in high treatment failure rates, unnecessary exposure to drug toxicities, and missed treatment opportunities. Recent advances in research on the tumor and microenvironmental factors of PTCL and NKTCL, including alterations in specific molecular features and immune signatures, have improved our understanding of these diseases, though several issues continue to impede progress in clinical translation. In this Review, we summarize the progress and development of the current predictive biomarker landscape, highlight potential knowledge gaps, and discuss the implications on novel therapeutics development in PTCL and NKTCL.

An ex vivo platform to guide drug combination treatment in relapsed/refractory lymphoma.

Although combination therapy is the standard of care for relapsed/refractory non-Hodgkin's lymphoma (RR-NHL), combination treatment chosen for an individual patient is empirical, and response rates remain poor in individuals with chemotherapy-resistant disease. Here, we evaluate an experimental-analytic method, quadratic phenotypic optimization platform (QPOP), for prediction of patient-specific drug combination efficacy from a limited quantity of biopsied tumor samples. In this prospective study, we enrolled 71 patients with RR-NHL (39 B cell NHL and 32 NK/T cell NHL) with a median of two prior lines of treatment, at two academic hospitals in Singapore from November 2017 to August 2021. Fresh biopsies underwent ex vivo testing using a panel of 12 drugs with known efficacy against NHL to identify effective single and combination treatments. Individualized QPOP reports were generated for 67 of 75 patient samples, with a median turnaround time of 6 days from sample collection to report generation. Doublet drug combinations containing copanlisib or romidepsin were most effective against B cell NHL and NK/T cell NHL samples, respectively. Off-label QPOP-guided therapy offered at physician discretion in the absence of standard options (n = 17) resulted in five complete responses. Among patients with more than two prior lines of therapy, the rates of progressive disease were lower with QPOP-guided treatments than with conventional chemotherapy. Overall, this study shows that the identification of patient-specific drug combinations through ex vivo analysis was achievable for RR-NHL in a clinically applicable time frame. These data provide the basis for a prospective clinical trial evaluating ex vivo-guided combination therapy in RR-NHL.

A genomic-augmented multivariate prognostic model for the survival of natural-killer/T-cell lymphoma patients from an international cohort.

With lowering costs of sequencing and genetic profiling techniques, genetic drivers can now be detected readily in tumors but current prognostic models for Natural-killer/T cell lymphoma (NKTCL) have yet to fully leverage on them for prognosticating patients. Here, we used next-generation sequencing to sequence 260 NKTCL tumors, and trained a genomic prognostic model (GPM) with the genomic mutations and survival data from this retrospective cohort of patients using LASSO Cox regression. The GPM is defined by the mutational status of 13 prognostic genes and is weakly correlated with the risk-features in International Prognostic Index (IPI), Prognostic Index for Natural-Killer cell lymphoma (PINK), and PINK-Epstein-Barr virus (PINK-E). Cox-proportional hazard multivariate regression also showed that the new GPM is independent and significant for both progression-free survival (PFS, HR: 3.73, 95% CI 2.07-6.73; p < .001) and overall survival (OS, HR: 5.23, 95% CI 2.57-10.65; p = .001) with known risk-features of these indices. When we assign an additional risk-score to samples, which are mutant for the GPM, the Harrell's C-indices of GPM-augmented IPI, PINK, and PINK-E improved significantly (p < .001, χ2 test) for both PFS and OS. Thus, we report on how genomic mutational information could steer toward better prognostication of NKTCL patients.

CREBBP cooperates with the cell cycle machinery to attenuate chidamide sensitivity in relapsed/refractory diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) exhibits frequent inactivating mutations of the histone acetyltransferase CREBBP, highlighting the attractiveness of targeting CREBBP deficiency as a therapeutic strategy. In this study, we demonstrate that chidamide, a novel histone deacetylase (HDAC) inhibitor, is effective in treating a subgroup of relapsed/refractory DLBCL patients, achieving an overall response rate (ORR) of 25.0% and a complete response (CR) rate of 15.0%. However, the clinical response to chidamide remains poor, as most patients exhibit resistance, hampering the clinical utility of the drug. Functional in vitro and in vivo studies have shown that CREBBP loss of function is correlated with chidamide sensitivity, which is associated with modulation of the cell cycle machinery. A combinatorial drug screening of 130 kinase inhibitors targeting cell cycle regulators identified AURKA inhibitors, which inhibit the G2/M transition during the cell cycle, as top candidates that synergistically enhanced the antitumor effects of chidamide in CREBBP-proficient DLBCL cells. Our study demonstrates that CREBBP inactivation can serve as a potential biomarker to predict chidamide sensitivity, while combination of an AURKA inhibitor and chidamide is a novel therapeutic strategy for the treatment of relapsed/refractory DLBCL.

Multiomic analysis and immunoprofiling reveal distinct subtypes of human angiosarcoma.

Angiosarcomas are rare, clinically aggressive tumors with limited treatment options and a dismal prognosis. We analyzed angiosarcomas from 68 patients, integrating information from multiomic sequencing, NanoString immuno-oncology profiling, and multiplex immunohistochemistry and immunofluorescence for tumor-infiltrating immune cells. Through whole-genome sequencing (n = 18), 50% of the cutaneous head and neck angiosarcomas exhibited higher tumor mutation burden (TMB) and UV mutational signatures; others were mutationally quiet and non-UV driven. NanoString profiling revealed 3 distinct patient clusters represented by lack (clusters 1 and 2) or enrichment (cluster 3) of immune-related signaling and immune cells. Neutrophils (CD15+), macrophages (CD68+), cytotoxic T cells (CD8+), Tregs (FOXP3+), and PD-L1+ cells were enriched in cluster 3 relative to clusters 2 and 1. Likewise, tumor inflammation signature (TIS) scores were highest in cluster 3 (7.54 vs. 6.71 vs. 5.75, respectively; P < 0.0001). Head and neck angiosarcomas were predominant in clusters 1 and 3, providing the rationale for checkpoint immunotherapy, especially in the latter subgroup with both high TMB and TIS scores. Cluster 2 was enriched for secondary angiosarcomas and exhibited higher expression of DNMT1, BRD3/4, MYC, HRAS, and PDGFRB, in keeping with the upregulation of epigenetic and oncogenic signaling pathways amenable to targeted therapies. Molecular and immunological dissection of angiosarcomas may provide insights into opportunities for precision medicine.

PRDM15 is a key regulator of metabolism critical to sustain B-cell lymphomagenesis.

PRDM (PRDI-BF1 and RIZ homology domain containing) family members are sequence-specific transcriptional regulators involved in cell identity and fate determination, often dysregulated in cancer. The PRDM15 gene is of particular interest, given its low expression in adult tissues and its overexpression in B-cell lymphomas. Despite its well characterized role in stem cell biology and during early development, the role of PRDM15 in cancer remains obscure. Herein, we demonstrate that while PRDM15 is largely dispensable for mouse adult somatic cell homeostasis in vivo, it plays a critical role in B-cell lymphomagenesis. Mechanistically, PRDM15 regulates a transcriptional program that sustains the activity of the PI3K/AKT/mTOR pathway and glycolysis in B-cell lymphomas. Abrogation of PRDM15 induces a metabolic crisis and selective death of lymphoma cells. Collectively, our data demonstrate that PRDM15 fuels the metabolic requirement of B-cell lymphomas and validate it as an attractive and previously unrecognized target in oncology.

Evaluation of the PIK3 pathway in peripheral T-cell lymphoma and NK/T-cell lymphoma.

Peripheral T-cell lymphomas (PTCL) and natural killer (NK)/T-cell lymphomas (NKTCL) are a heterogeneous group of aggressive malignancies with dismal outcomes and limited treatment options. While the phosphatidylinositol 3-kinase (PIK3) pathway has been shown to be highly activated in many B-cell lymphomas, its therapeutic relevance in PTCL and NKTCL remains unclear. The aim of this study is to investigate the expression of PIK3 and phosphatase and tensin homolog (PTEN) in these subtypes of lymphoma and to identify potential therapeutic targets for clinical testing. Therefore, the expression of PIK3α, PIK3ß, PIK3γ, PIK3δ and PTEN was analyzed in 88 cases of PTCL and NKTCL samples by immunohistochemistry. All PTCL and NKTCL samples demonstrated high expression of PIK3 isoforms. In particular, high PIK3α expression was significantly associated with poor survival, even after adjustment for age, International Prognostic Index (IPI) score and anthracycline-based chemotherapy in first line. Notably, copanlisib, a pan-class I inhibitor with predominant activities towards PIK3α and PIK3δ isoforms, effectively inhibited phosphorylation of AKT, 4E-BP-1 and STAT3, causing G0 /G1 cell cycle arrest and resulting in suppression of tumour cell growth in vitro and in vivo. This study provides evidence that targeting the PIK3 pathway, particularly simultaneous inhibition of PIK3α and δ, could be a promising approach for the treatment of PTCL and NKTCL.