Abstract: Abstract 441 New treatment strategies that potentially change the natural course of intermediate (int)-2 and high risk myelodysplastic syndromes (MDS), such as azacitidine, are emerging. Recently, we reported that flow cytometric analysis of bone marrow (BM) in low and int-1 risk MDS is instrumental to identify clinically relevant subgroups. (Westers et al, Blood 2010) Moreover, it was reported that a flow cytometric scoring system (FCSS) is predictive for worse outcome in MDS. (Wells et al, Blood 2003, van de Loosdrecht et al, Blood 2008) The FCSS is a scoring system that allows for a numerical display of immunophenotypic aberrancies in the (im)mature myelo-monocytic lineage. Scores are generated by enumerating abnormalities; e.g. high scores reflect a high number of aberrancies. The current study aimed to investigate the role of this flow cytometry-based scoring system to assess and monitor response to treatment in int-2 and high risk MDS patients treated with azacitidine. Bone marrow aspirates were analyzed by flow cytometry in 18 MDS patients who were treated with azacitidine. Aspirates were drawn before treatment and after every third cycle of azacitidine. Response to treatment was evaluated using IWG-2006 criteria. The median age was 71 (range 50–78). Distribution over WHO 2001 categories was RCMD-RS n=2, RAEB-2 n=7, AML with 20–30% blasts n=6 and MDS/MPD n=3. International prognostic scoring system (IPSS) categories comprised int-2 n=8 and high n=5. In 5 patients the IPSS score could not be assessed due to lack of cytogenetics, these patients were at least int-2 MDS patients. Flow cytometric follow up was available in 12 patients due to short follow up, i.e. in 4 responders, 4 progressive disease (PD) and 4 stable disease (SD) patients; 3 patients stopped due to non-hematologic toxicity, 4 patients died of PD. Median follow up was 7 months (range 3–12). Median pre-treatment Hb was 6.7 mmol/L, platelets 35.5*10e9/L and absolute neutrophil count (ANC) 0.82*10e9/L. Responders had a significant increase in Hb (median 7.8 mmol/L, p=0.04), platelets (291.5 *10e9/L, p=0.03) and ANC (1.4*10e9/L, p=n.s. compared with baseline values). SD and PD patients had a median Hb of 6.5 mmol/L, platelets 69*10e9/L and ANC 0.77*10e9/L. The median pre-treatment flow score was 6 (range 3–8). Interestingly, responders had a significant decrease in flow score from median 5 to median 2 (range 1–3, p=0.005) after 3 months of treatment. No change in flow scores was seen in PD and SD patients after 3 months of treatment (median=6, range 4–8 and pre-treatment FCSS median=6.5, range 3–8). A sustained decrease in flow score was seen in 4 responders after 6 months of treatment (median 2, range 1–3) parallel to a further increase in median Hb (9.0 mmol/L), platelets (278.5 *10e9/L) and ANC (1.7*10e9/L). After 9 cycles of azacitidine, 3 patients were still responsive to treatment (median Hb 9.9 mml/L, platelets 169, ANC 4.07, median flow score 5, range 2–4). The majority of SD and PD MDS patients had aberrant marker expression on myeloid progenitors, such as CD5, CD7 and/or CD56 compared with responsive MDS patients, (63% (5/8) vs 25% (1/4). Moreover, initial loss of aberrant marker expression on myeloid progenitors was detected in one patient who responded to azacitidine treatment. At 9 months, this initially responsive patient and a patient from the stable disease group developed progressive disease. Interestingly, the initially responsive patient showed an increase in the percentage of myeloid progenitors with an aberrant immunophenotype at 6 months; of note, the total percentage of CD34+ cells was less than 3% by flow cytometry. The initial loss of aberrant marker expression on myeloid progenitors might be caused by a relative increase of normal progenitors and decrease of malignant progenitors caused by azacitidine treatment. In conclusion, our data indicate that flow cytometry identifies MDS patients who may benefit from azacitidine treatment by detection of aberrant marker expression on myeloid progenitors. Moreover, the data indicate that the FCSS may be instrumental in selection of SD patients who may benefit from prolonged treatment with azacitidine. Disclosures: Ossenkoppele: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Van de Loosdrecht:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract: Myelodysplastic syndromes (MDS) are a group of clonal disorders of the bone marrow characterized by peripheral cytopenias. Standard treatment in low- and intermediate-I–risk MDS is supportive therapy consisting of regular transfusions and growth factors, that is, erythropoietin (Epo) and granulocyte-colony-stimulating factor (G-CSF). Because flow cytometric analysis of MDS bone marrow samples can identify clinically relevant subgroups regarding transfusion dependency and disease progression, we addressed the question whether flow cytometry (FCM) was instrumental in predicting response. In 46 patients with low- and intermediate-I–risk MDS that were treated with Epo/G-CSF, low Epo level and low transfusion need were associated with response to Epo/G-CSF. Interestingly, aberrant phenotype of myeloblasts identified nonresponders among patients with the greatest response probability according to the predictive model of Hellström-Lindberg et al. Moreover, aberrant FCM of myeloblasts acted as a significant biomarker for treatment failure in multivariate analysis. A new predictive model based on the basis FCM combined with previously validated Epo levels is proposed defining 3 subgroups with 94%, 17%, and 11% response probability. In conclusion, FCM may add significantly to well-known predictive parameters in selecting MDS patients eligible for Epo/G-CSF treatment. This is of relevance regarding prevention of treatment failure.

Abstract: Introduction: The incidence and prevalence of patients with Myelodysplastic Syndromes (MDS) are continuously rising due to population ageing and diagnostic advances. Consequently, the appropriate use of health care resources and assessment of their impact on relevant outcomes are of growing interest. Several evidence-based guidelines and recommendations (G & Rs) have been published for adult MDS patients. However, publishing G & Rs does not necessarily translate into better quality of care. Several studies have shown that MDS patients are not always treated according to published G & Rs, but systematic investigations have not been done so far. To this aim, we initiated the I-CARE for MDS study with the objectives to i) define relevant guideline-based indicators (GBIs) as measurable elements of practice performance for appropriate care, ii) assess the level of adherence and reasons for non-adherence to GBIs and iii) investigate the impact of adherence/non-adherence to GBIs on MDS relevant outcomes. Here we present results of the development of GBIs for appropriate care in adult MDS patients. Methods: We systematically screened G & Rs from cooperative MDS groups as well as cancer care accreditation/certification programs (table 1). All relevant information was extracted by a structured procedure and summarized as candidate GBIs in a handbook (table 2). We applied a RAND technique with a two-step DELPHI rating procedure to find an expert consensus for the clinically most relevant GBIs (Coulter J et al, J Health Serv Res Policy, 2018). The expert panel group (EPGs) members consisted of 17 internationally acknowledged MDS experts, 7 additional health-professionals (3 nurses, 1 pharmacologist, 1 physiotherapist, 1 psychologist and 1 epidemiologist) and 3 patient advocates. Candidate GBIs were rated using a 9-point Likert-like scale for Relevance, Understandability, Measurability, Behaviorability, Attainability (RUMBA-criteria) and ranked according to the agreement score, defined as % of all EPG members scoring all RUMBA-criteria in the first tertile (9, 8, or 7). Results: We extracted 61 candidate GBIs from G & Rs for the three domains Diagnostics (n=23), Treatment (n=21) and Provider characteristics (n=17). 18 and 16 candidate GBIs were excluded after the first and second round, respectively, remaining with a set of 27 GBIs (figures 1-3). Twelve GBIs were selected for Diagnostics (figure 1). Patient reported outcomes (PROs), Toxicity assessment (TAs) and Geriatric assessment were excluded as there was no agreement among experts on appropriate measurement instruments and concerns for practicability in daily routine. Eight GBIs were selected for Treatment (figure 2). Iron-chelation and Immunosuppressive treatment, even though mentioned in most G & Rs, were excluded, as there were concerns with regard to controversial indications, side effects and benefit for only a minority of patients. Seven GBIs were selected for Provider characteristics (figure 3), which will be generally fulfilled by accreditation or certification of institutions. Agreement scores were generally higher in this domain and required a more stringent threshold for selection of GBIs. Conclusions: Here we report on the development of relevant GBIs for the management of adult MDS patients covering the domains of Diagnostics, Treatment and Provider characteristics. Our preliminary set GBIs represents the most comprehensive integration of current practice based G & Rs and were developed by a structured consensus process involving internationally acknowledged experts. We identified important shortcomings in standardisation, measurability and practicability, especially for PROs and TAs, which asks for improvements in the future. Even though PROs and TAs are generally acknowledged endpoints for efficacy and safety, respectively, they are yet not standardised outside clinical trials or validated to inform routine MDS care. Our preliminary set of GBIs will be tested for applicability/operability as well as validated for their potential impact on relevant outcomes in MDS cohorts. They will eventually enable to systematically monitor, compare and optimize appropriateness of health care provided to MDS patients in everyday clinical practice. As such, GBIs will be important for the realization of a common standard for value-based medicine in economically driven health care systems with limiting resources. Disclosures Fenaux: Celgene Corporation: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Aprea: Research Funding; Astex: Honoraria, Research Funding. Germing:Novartis: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria; Celgene: Honoraria, Research Funding. Pfeilstocker:Janssen-Cilag: Honoraria; Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Platzbecker:Celgene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Medina De Almeida:Celgene: Speakers Bureau; Novartis: Speakers Bureau. Mittelman:Novartis: Honoraria, Research Funding, Speakers Bureau. Steensma:H3 Biosciences: Other: Research funding to institution, not investigator.; Stemline: Consultancy; Arrowhead: Equity Ownership; Aprea: Research Funding; Pfizer: Consultancy; Onconova: Consultancy; Astex: Consultancy; Summer Road: Consultancy. Santini:Menarini: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Acceleron: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees. Stauder:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Teva (Ratiopharm): Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Advisory board, Research Funding. Symeonidis:MSD: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding; Tekeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding. de Witte:Novartis: Research Funding; celgene: Research Funding; Amgen: Research Funding. Bonadies:Novartis: Other: financial support for travel, Research Funding; Celgene: Other: financial support for travel, Research Funding; Janssen: Other: financial support for travel; Roche: ; Amgen: Other: financial support for travel.

Abstract: Abstract 1860 Immune editing is recognized as being important in the pathogenesis of myelodysplastic syndrome (MDS). In low risk MDS, inappropriate immune reactions are thought to contribute to the initiation and progression of the disease. IL-17 producing CD4+ T-helper cells have been associated with various autoimmune diseases and are found in increased frequencies in low-risk MDS. These increased Th17 frequencies are accompanied by a reduced FoxP3+ T-regulatory (Treg) frequency. On the other hand, in high-risk MDS, the elevated number of bone marrow blasts was associated with increased numbers of Treg. These increased Treg may inhibit immune responses directed against the dysplastic blasts and as such permit progression of the disease. The demethylating agents ‘5-aza-2’-deoxycytidine and ‘5-azacitidine (Aza) have shown significant clinical benefits in the treatment of MDS. Although aberrant DNA methylation patterns appear to play a role in the pathogenesis of MDS, clinical responses to DNA demethylating agents could not be related to changes in DNA methylation patterns. Cytokine production and FoxP3 expression are also regulated by epigenetic mechanisms, and FoxP3 expression is increased upon in vitro treatment with Aza. Since cytokines and FoxP3+ Treg may play a role in the pathogenesis of MDS, we set out to investigate the effects of Aza (Vidaza®) treatment on CD4+ T-helper subset frequencies in high-risk MDS patients. Nine patients treated with 75 mg/m2/day subcutaneously for 7 consecutive days in a 28 day cycle were included in this study. Peripheral blood samples were drawn before, 15 days after start of treatment and at the end of the third cycle. There was no change in absolute or relative CD3+ and CD3+CD4+ T-cell numbers during treatment. The proportion of Treg was slightly but not significantly increased (paired student's T-test, p=0.08) on day 15 (11.9 % of CD4+) compared to levels before treatment (9.6 % of CD4+) while numbers dropped to pretreatment levels after the third cycle(9.6 % of CD4+). Cytokine producing cells were enumerated after stimulation with phorbol-12-myristate-13-acetate (PMA) and ionomycin in the presence of Brefeldin A. No significant changes in IFNγ (23.8%, 22.5% and 17.9% of CD4+ cells pretreatment, 15d post treatment and after the third cycle respectively) TNFα (38.3, 35.9 and 39.3% of CD4+ cells) or IL-4 (0.6, 1.0 and 0.6% of CD4+ cells) producing cells were observed. However, the proportion of IL-17 producing cells progressively decreased during treatment (1.1, 0.7 and 0.6% of CD4+ cells; ANOVA, p=0.006). In conclusion, Aza may modulate the immune response and in particular reduce IL-17 responses. This effect of Aza may provide a rationale for expanding the group of patients eligible for Aza treatment with low risk MDS patients, because low risk MDS has been associated with elevated, potential pathogenic, Th17 cells. Disclosures: Ossenkoppele: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Van de Loosdrecht:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding.