S4 EORTC Cutaneous Lymphoma Task Force Meeting 2019 abstract book | European Journal of Cancer 119S1 (2019) S1–S44 compared the results to other 18 cases of systemic PTCL-NOS without skin involvement (36 cases in total). Conclusion: Our series evidence the importance of the skin involvement at diagnosis and also at disease relapse on systemic PTCL-NOS. We also highlight the importance of recognizing a group of indolent cases. Even though described with an aggressive behavior, there is a high heterogeneity on this group and aggressive therapy is often, but not always, mandatory. 010 In vitro effect of Jak and HDAC inhibitors in cutaneous T-cell lymphoma F. Karagianni 1 , K. Saraki 1 , M. Papadaki 1 , V. Mpakou 2 , C. Piperi 3 , V. Pappa 2 , E. Papadavid 1 1 2nd Department of Dermatology and Venereal Diseases, National and Kapodistrian University of Athens Medical School, Athens, Greece 2 2nd Department of Internal Medicine and Research Institute, National and Kapodistrian University of Athens Medical School, Athens, Greece 3 Department of Biological Chemistry, National and Kapodistrian University of Athens Medical School, Athens, Greece Introduction: The therapeutic role of Jak and HDAC inhibitors have been explored in hematological malignancies, many of them in clinical trials. We investigated the role of inhibitors of JAK1,2 , ruxolitinib and HDAC 6, resminostat in vitro in proliferation, apoptosis, cytokine expression profiling and the implicated signaling pathways in CTCL cell lines. Material and methods: The MF (MyLa) and SS (SeAx) cell lines were cultured in the absence/ presence of ruxolitinib and/or resminostat at appropriate concentration at different time points. The proliferation status was studied using an MTT assay at the absence/presence of the drug. The apoptotic rate was determined through Annexin V/PI staining in untreated and drug-treated cells. The cytokine expression of IFNγ, IL2, IL4, IL17 and TGFβ and a multipathway analysis (Akt, CREB, Erk/MAPK, JNK/SAPK1, NFκB, p38, p70S6 kinase, STAT3 and STAT5A/B) were determined by Luminex Technology. Results: Ruxolitinib and resminostat inhibited cell proliferation either as monotherapy or combination compared to untreated cells but the best effect was shown with the single drug resminostat (p<0.001) in both cell lines whereas the combined use of these inhibitors induced apoptosis at significant level in both cell lines 40% p<0.001 for Myla and 20% p<0.001 for SeAx). An altered expression profile of CTCL-associated inflammatory cytokines after the drug treatments were also detected indicating a shift from Th2 to Th1 phenotype. Moreover, treatment with the above drugs inhibited the phosphorylation of key molecules in CTCL development which have a crucial role of the cross talk between different pathways. Conclusion: Use of JAK/STAT and HDAC inhibitors seems to offer substantial anti-tumor benefit, and combined therapy of Jak and HDAC inhibitors may represent a promising novel therapeutic modality for CTCL. 011 A retrospective analysis of patients with co-existent mycosis fungoides and primary cutaneous anaplastic large cell lymphoma from the Australian Cutaneous Lymphoma Network database C. Gao 1,2 , C. McCormack 1,3 , C. van der Weyden 1 , R. Twigger 1 , O. Buelens 1 , S. Lade 1 , C. Khoo 1 , B.A. Campbell 1,4 , M. Goh 1,3 , P. McKelvie 3 , H.M. Prince 1,2,4 1 Peter MacCallum Cancer Centre, Melbourne, VIC Australia 2 Monash University, Clayton, VIC Australia 3 St Vincent’s Hospital, Fitzroy, VIC Australia 4 University of Melbourne, Parkville, VIC Australia It can be difficult to distinguish between patients with mycosis fungoides (MF) with large-cell transformation (LCT), or patients with the clinically similar MF with co-existent primary cutaneous anaplastic large- cell lymphoma (pcALCL). The purpose of this study was to investigate patients with MF/LCT and those with MF/pcALCL and compare their overall survival (OS) against patients with MF-alone, or pcALCL-alone. The following cohort were analyzed and compared, with study endpoints including OS and time-to-next-treatment (TTNT): MF/LCT (n=40); MF/ pcALCL (n=13); MF-alone (n=95); pcALCL-alone (n=51). Our analysis of the data showed a significant difference in OS between patients with MF/LCT (median predicted OS 80 months) and patients with MF/pcALCL (median predicted OS not reached, p=0.05). MF/pcALCL seemed to represent a much less aggressive disease entity with prognosis similar to that of patients with pcALCL-alone (median predicted OS not reached, p=0.82) and MF-alone (median predicted OS not reached, p=0.99). Furthermore, patients with MF/LCT required more treatment lines compared to patients with MF/pcALCL (median systemic agents required: seven versus four respectively) and had a significantly shorter TTNT of four months compared to those with MF/pcALCL (eight months, p=0.0097). Overall, our results suggest that MF/pcALCL represents a distinct disease entity with better survival and treatment outcomes compared to the clinically similar MF/LCT. This emphasizes the need to carefully differentiate between these two conditions as it will have important implications for both the clinicians’ choice of treatment, as well as patient prognosis. 012 Malignant, benign conventional and regulatory T immune compartments in 36 patients treated with mogamulizumab for advanced CTCL M. Roelens 1,2 *, A. de Masson 1,3 *, M. Battistella 1,4 *, S. Mourah 1,5 , M.J. Estevez 1,2 , J. Delyon 1,3 , F. Herms 3 , C. Ram-Wolff 3 , C. Lebbé 1,3 , M. Bagot 1,3 *, H. Moins-Teisserenc 1,2,6 * 1 Université de Paris, Paris, France 2 INSERM UMR1160, Paris, France 3 Dermatology, Hôpital Saint-Louis, Paris, France 4 Pathology, Hôpital Saint-Louis, Paris, France 5 Pharmacogenomics, Hôpital Saint-Louis, Paris, France 6 Hematology Laboratory, Hôpital Saint-Louis, Paris, France *Equal contributors Mogamulizumab, an anti-CCR4 monoclonal antibody, has shown to increase progression-free survival compared to vorinostat in previously treated cutaneous T-cell lymphoma (CTCL). We recently reported 2 long- lasting complete remissions associated with multiple autoimmune mani- festations. We monitored circulating regulatory T-cells (Treg), conventional T-cells (CD8 + , benign CD4 + KIR3DL2 – TCRVb – Tconv) and KIR3DL2 + TCRVb + tumor cells from 36 patients treated with mogamulizumab for advanced CTCL. Sixteen patients from the MAVORIC phase 3 study were retro- spectively analyzed. Twenty additional patients were included (11/2018– 03/2019) and studied prospectively. Twenty-seven patients had Sézary syndrome (SS) and 9 Mycosis Fungoides (MF). The overall response rate was 70% in SS and 33% in MF. Although most patients displayed low Treg counts before and during treatment, the three patients who developed grade 3 autoimmune side-effects had particularly low initial effector Treg counts, or experienced a dramatic decrease of this subset during treatment. Mogamulizumab induced a marked decrease in circulating tumor cells, and significant changes within CD8 + and CD4 + benign T-cells, with an increase of naïve Tconv and a decrease