Sézary Syndrome is a rare leukemic form of cutaneous T-cell lymphoma defined as erythroderma, adenopathy, and circulating atypical T-lymphocytes. It is rarely curable with poor prognosis. Here we present a multi-platform genomic analysis of 37 Sézary Syndrome patients that implicates dysregulation of the cell cycle checkpoint and T-cell signaling. Frequent somatic alterations were identified in TP53, CARD11, CCR4, PLCG1, CDKN2A, ARID1A, RPS6KA1, and ZEB1. Activating CCR4 and CARD11 mutations were detected in nearly a third of patients. ZEB1, a transcription repressor essential for T-cell differentiation, was deleted in over half of patients. IL32 and IL2RG were over-expressed in nearly all cases. Analysis of T-cell receptor Vβ and Vα expression revealed ongoing rearrangement of the receptors after the expansion of a malignant clone in one third of subjects. Our results demonstrate profound disruption of key signaling pathways in Sézary Syndrome and suggest potential targets for novel therapies.

Cutaneous T-cell lymphomas (CTCLs) are extremely symptomatic and still incurable, and more effective and less toxic therapies are urgently needed. ONC201, an imipridone compound, has shown efficacy in pre-clinical studies in multiple advanced cancers. This study was to evaluate the anti-tumor activity of ONC201 on CTCL cells. The effect of ONC201 on the cell growth and apoptosis were evaluated in CTCL cell lines (n=8) and primary CD4+ malignant T cells isolated from CTCL patients (n=5). ONC201 showed a time-dependent cell growth inhibition in all treated cell lines with a concentration range of 1.25-10.0 μM. ONC201 also induced apoptosis in tested cells with a narrow concentration range of 2.5-10.0 μM, evidenced by increased Annexin V+ cells, accompanied by accumulated sub-G1 portions. ONC201 only induced apoptosis in CD4+ malignant T cells, not in normal CD4+ T cells. The activating transcription factor 4 (ATF4), a hallmark of integrated stress response, was upregulated in response to ONC201 whereas Akt was downregulated. In addition, molecules in JAK/STAT and NF-κB pathways, as well as IL-32β, were downregulated following ONC201 treatment. Thus, ONC201 exerts a potent and selective anti-tumor effect on CTCL cells. Its efficacy may involve activating integrated stress response through ATF4 and inactivating JAK/STAT and NF-κB pathways.

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Background/PurposeWe previously reported that myeloid dendritic cells (mDC) were increased in patients with leukemic cutaneous T‐cell lymphoma (L‐CTCL) following extracorporeal photopheresis (ECP) using the Therakos UVAR XTS™ system. We now assessed monocyte‐derived mDCs (Mo‐DCs) in L‐CTCL patients treated with the CELLEXTM photopheresis system. CD209, a transmembrane receptor, was used to define Mo‐DCs.MethodsPeripheral blood samples from baseline pre‐ECP and at Day 2, 1 month, 3 months, and 6 months post‐ECP were analyzed by flow cytometry for Lin−HLA‐DR+CD123+ plasmacytoid dendritic cells (pDCs), Lin−HLA‐DR+CD11c+ mDCs, and CD209+ mDCs. The expression of CD209 mRNA was assessed by real‐time PCR.ResultsAt baseline, 7 of 19 patients had lower than normal mDCs, and all patients had lower than normal CD209+ mDCs in peripheral blood mononuclear cells (0.005% in patients, n = 19, vs 0.50% in healthy donors, n = 7, P < .0001). The CD209+ mDC numbers only accounted for 3.28% out of total mDCs in patients compared with 66.51% in healthy donors. After treatment, the CD209+ mDC numbers showed increasing trends in patients. The average absolute numbers of CD209+ mDCs went up by 4.8‐fold at 3 months (n = 10, P = .103) and by 6.4‐fold at 6 months (n = 9, P = .100). CD209 mRNA expression went up in two patients responsive to therapy, parallel to CD209+ mDC numbers. L‐CTCL patients achieved 70% overall clinical response rate (7/10) following ECP therapy with the CELLEXTM system.ConclusionsOur results suggest that the CELLEXTM photopheresis system is effective for treating L‐CTCL patients like the UVAR XTS™ system, and in vivo‐generated Mo‐DCs increase following ECP.

Background: ONC201 (also called TIC10) is an orally active, first-in-class small molecule that is in phase II clinical trials for advanced cancers based on its ability to activate apoptosis in tumor cells, but not normal cells, in a p53-independent manner. Recent studies have implicated the integrated stress response as an early stage mechanism of ONC201 that may lead to the previously observed downstream anti-cancer effects. This study was conducted to evaluate the anti-tumor activity of ONC201 on Cutaneous T-Cell Lymphoma (CTCL) cell lines and Sézary cells. Methods: We treated 8 CTCL cell lines (H9, HH, Hut78, Mac2A, MJ, MyLA, Pb2b and SeAx), peripheral blood mononuclear cells (PBMC) from 5 Sézary syndrome (SS) patients and 6 healthy donors with ONC201. MTS viability Assay was used to assess the anti-proliferation effect. Apoptosis was assessed using Annexin V FITC/PI staining and sub-G1 analysis by flow cytometry. Protein expression by western blotting was analyzed in 3 CTCL cell lines (HH, Hut78, MJ) and in PBMCs from 2 SS patients treated for 72 hours with ONC201including Activating Transcription Factor 4 (ATF4), interferon regulatory factor 7 (IRF7/pIRF7), Signal transducer and activator of transcription 3 (STAT3), Janus Kinase 3 (JAK3/pJAK3) and NF-κB family members (p65, RelB, c-Rel and p105). Results: MTS viability assay showed pronounced cell growth inhibition, significantly increasing in a time-dependent manner in H9, HH, Hut78, Mac2A, MJ, MyLa, Pb2b, and SeAx lines after a 96-hour incubation within a very narrow efficacy threshold ranging from 1.25 to 10µM (n = 8, p < 0.05). To determine whether growth inhibition of ONC201 is due to cell-cycle arrest and/or to apoptosis in CTCL cell lines, sub-G1 analysis by flow cytometry was measured in 3 CTCL cell lines (HH, Hut78 and MJ). The percentages of HH, Hut78 and MJ cells with sub-G1 population increased, suggesting that cells are undergoing apoptosis (n = 3, p < 0.05). Induction of apoptosis was further confirmed by Annexin V FITC/PI staining, revealing dose and time dependent apoptosis induction in all 8 cell lines (Figure 1). To confirm cell line results in refractory ex vivo samples, we tested the pro-apoptotic effects of ONC201 on PBMCs from 5 SS patients who had high circulating CD4+CD26- malignant T-cells compared with PBMCs from 6 healthy donors. ONC201 induced significant levels of apoptosis in PBMCs from SS patients, but not in normal PBMCs (Figure 1, p < 0.001). Western blot analysis revealed that ONC201 increased the expression of ATF4, a hallmark of the integrated stress response and a negative regulator of IRF7. ONC201 decreased expression of IRF7/pIRF7 and down-regulated JAK3/pJAK3 and STAT3 expression in CTCL cell lines and PBMCs from SS patients. ONC201 also decreased the protein expression of NF-κB family members ( p65, RelB, c-Rel and p105) that can cause resistance to apoptosis in CTCL cells. Conclusions: ONC201 appears to be active as a single oral agent. It may impact key signaling pathways in CTCL preclinical models by inhibiting proliferation and inducing apoptosis through a mechanism that involves the integrated stress response, leading to inactivation of JAK/STAT signaling and down-regulation of the NFκB pathway. Figure 1. ONC201 induces apoptosis in CTCL cell lines and PBMCs from SS patients Figure 1. ONC201 induces apoptosis in CTCL cell lines and PBMCs from SS patients Disclosures Duvic: Eisai: Research Funding; MiRagen Therapeutics: Consultancy; Cell Medica Ltd: Consultancy; Tetralogics SHAPE: Research Funding; Soligenics: Research Funding; Array Biopharma: Consultancy; Innate Pharma: Research Funding; Allos (spectrum): Research Funding; Rhizen Pharma: Research Funding; Spatz Foundation: Research Funding; Oncoceutics: Research Funding; Huya Bioscience Int'l: Consultancy; Therakos: Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kyowa Hakko Kirin, Co: Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: Most drugs for ctcl are non approved. This drug is a small molecule and is not approved for any cancer. Tarapore:Oncoceutics, Inc: Employment, Equity Ownership. Allen:Oncoceutics, Inc: Employment, Equity Ownership.

Extracorporeal photopheresis (ECP) is an effective frontline therapy for patients with leukemic cutaneous T-cell lymphoma (L-CTCL), but the mechanisms of action are not fully understood. To elucidate molecular mechanisms underlying the efficacy of ECP, we used Agilent Whole Human Genome Microarrays to examine blood transcriptional profiles in L-CTCL patients after ECP therapy. Ten L-CTCL patients including 5 clinical responders and 5 non-responders were studied. Their peripheral blood was collected before ECP (baseline), at Day 2, and one month post-ECP. Total RNA extracted from peripheral blood mononuclear cells was assayed with Whole Human Genome Oligo Microarrays (4 × 44 K) (Agilent, Santa Clara, CA). The differentially expressed gene analysis (DGA) was done using the paired t-test with Benjamini- Hochberg correction (P value < 0.05) between post-ECP and baseline. The fold change of gene expression between post-ECP and baseline were calculated from the normalized values. Hierarchical clustering of differentially expressed genes was performed with the Pearson correlation. The DGA between responders and non-responders were cross-compared. Canonical biological pathways were identified using Ingenuity Pathway Analysis (IPA, Ingenuity Systems, Redwood City, CA). Differentially expressed gene profiles were different in responders from non-responders. As indicated in Figure 1, there were more genes differentially regulated in responders than in non-responders post-ECP at both Day 2 (549 genes in responders versus 66 genes in non-responders) and at one month (472 genes in responders versus 95 genes in non-responders). Among 472 differentially expressed genes in responders at one month post-ECP, almost twice as many genes (313) were down-regulated compared to up-regulated genes (159). The top down-regulated genes were IL-1β, EGR1, CCL3, CCL3L3, and CXCL2. The down-regulated genes were mainly related to functions of platelets, immune and/or stress responses, and chromatin remodeling. The upregulated genes were mainly related to functions of the nucleolus and included USP34, POLR3F, ZNF529, C22orf35, and BAT2D1. The ingenuity pathway analysis revealed that the top 5 pathways affected by ECP at one-month in responders were 1) integrin signaling; 2) granulocyte adhesion and diapedesis; 3) signaling by Rho Family GPTases; 4) agranulocytes (lymphocyte, monocyte and macrophage) adhesion and diapedesis; and 5) triggering receptor expressed on myeloid cells 1 (TREM1) signaling (Table 1). In contrast, these pathways and genes were less affected in non-responders. Of note, a comparison of all DGA results indicated that the responder group overlapped in the differentially expressed genes between Day 2 group (RD2) and one month group (RM1), but had few genes in common to the non-responder group (NM1). There were 94 genes consistently downregulated among RD2 and RM1 while only 6 genes were found in common between the RM1 and NM1 group. Similarly, 61 genes were consistently upregulated in group RD2 and RM1 while only 3 genes were found in common between the RM1 and NM1 group. In summary, the blood transcriptional profiling by this study identifies a signature of genes and pathways relevant to clinical response to ECP in L-CTCL patients. These findings expand our understanding of molecular mechanisms of ECP. Further validation of these genes and pathways is warranted in the future studies. Table 1. Top canonical pathways affected by ECP in L-CTCL patients responded to ECP at one-month Canonical Pathways Downregulated genes Upregulated genes Integrin Signaling 15/201 (7%) ITGA2B, MAP3K11, ITGA5, MYLK, ITGB3, MYL9, PARVB, AKT1, RHOB, CAPN1, ACTN4, CTTN, ARPC4, ACTN1, ITGB5 2/201 (1%) ITGB1, PPP1R12A Granulocyte Adhesion and Diapedesis 14/179 (8%) CSF3R, ICAM1, PPBP,ITGA5, CXCL5, SDC4, CCL3, ITGB3, GNAI2, CLDN5, CCL3L3, IL1B, CXCL1, CXCL2 1/179 (1%) ITGB1 Signaling by Rho Family GTPases 13/236 (6%) SEPT5, MAP3K11, ITGA5, MYLK, GNAZ, CDC42EP2, GNAI2, MYL9, GNG11, GNA15, RHOB, GNB2, ARPC4 3/236 (1%) ITGB1, DIAPH3, PPP1R12A Agranulocyte Adhesion and Diapedesis 13/190 (7%) ICAM1, PPBP, ITGA5, CXCL5, SDC4, CCL3, GNAI2, MYL9, CLDN5, CCL3L3, IL1B, CXCL1, CXCL2 1/190 (1%) ITGB1 TREM1 Signaling 7/76 (9%) ICAM1, AKT1, NLRP12, ITGA5, IL1B, CD83, CCL3 2/76 (3%) ITGB1, NLRC3 Figure 1. Differentially expressed genes post-ECP between responders and non-responders Figure 1. Differentially expressed genes post-ECP between responders and non-responders Disclosures Duvic: Therakos: Research Funding. Ni:Therakos: Research Funding.

Flow cytometry analysis of T-cell receptor (TCR)-vb expression has been long used for assisting diagnosis of patients with cutaneous T-cell lymphoma (CTCL). But antibodies used in flow cytometry only covers 70% of TCR vb repertoire. The high throughput sequencing has been considered as a complete and sensitive method for monitoring malignant T-cell clones in CTCL. But it is expensive. Thus, an affordable method to profile TCR repertoires for patients with CTCL is still needed. In this study, we used a direct TCR expression assay (DTEA) to detect and quantify 111 TCR mRNA expressions (va¼45, vb¼46, vg¼15, and vd¼5) in patients with leukemic CTCL who underwent extracorporeal photopheresis (ECP). The total RNA (50ng) extracted from PBMCs of patients at baseline pre-ECP (n¼16) and 3 months (n¼12) and 6 months (n¼12) post-ECP was assayed. DTEA showed a higher sensitivity in detecting T-cell clones than flow cytometry. DTEA detected T-cell clones in 16 of 16 patients (100%) in comparison to 10 of 14 (71.4%) by flow cytometry. Ten patients who showed single TCR vb clone by flow cytometry, had double, triple, or multiple TCR vb clones by DTEA. DTEA profiled not only TCR vb repertoire but also va, vg, and vd repertoires. For 12 patients who had follow-up samples, TCR repertoires or malignant T-cell clones by DTEA were similar between baseline and after ECP in every patient. TCR v-gene expression in patients responsive to ECP declined while in patients resistant to ECP increased. Our results suggest that DTEA can sensitively detect and track changes in TCR-v gene usages in T-cell pool. This assay requires limited total RNA and costs only $100 per sample. Thus, it may serve as a good assay for clinical use for CTCL patients.

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