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Chronic Myeloid Leukemia is a clonal disorder characterized by the presence of the Ph-chromosome and the BCR-ABL tyrosine-kinase (TK). Target-therapy with Imatinib has greatly improved its outcome. Deeper and faster responses are reported with the second-generation TKI Nilotinib. Sustained responses may enable TKI discontinuation. However, even in a complete molecular response, some patients experience disease recurrence possibly due to persistence of quiescent leukemic CD34+/lin−Ph+ stem cells (LSCs). Degree and mechanisms of LSCs clearance during TKI treatment are not clearly established. The PhilosoPhi34 study was designed to verify the in-vivo activity and timecourse of first-line Nilotinib therapy on BM CD34+/lin−Ph+ cells clearance. Eighty-seven CP-CML patients were enrolled. BM cells were collected and tested for Ph+ residual cells, at diagnosis, 3, 6 and 12 months of treatment. FISH analysis of unstimulated CD34+/lin− cells in CCyR patients were positive in 8/65 (12.3%), 5/71 (7%), 0/69 (0%) evaluable tests, respectively. Per-Protocol analysis response rates were as follows: CCyR 95% at 12 months, MR4.5 31% and 46% at 12 and 36 months, respectively. An exploratory Gene Expression Profiling (GEP) study of CD34+/lin− cells was performed on 30 patients at diagnosis and after, on 79 patients at diagnosis vs 12 months of nilotinib treatment vs 10 healthy subjects. Data demonstrated some genes significantly different expressed: NFKBIA, many cell cycle genes, ABC transporters, JAK-STAT signaling pathway (JAK2). In addition, a correlation between different expression of some genes (JAK2, OLFM4, ICAM1, NFKBIA) among patients at diagnosis and their achievement of an early and deeper MR was observed.

BACKGROUND: Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder with heterogeneous biological and clinical features. The biomolecular mechanisms of CML response to tyrosine-kinase inhibitors are not fully defined. OBJECTIVE: We undertook a gene expression profiling (GEP) study of selected bone marrow (BM) CD34+/lin-cells of chronic-phase CML patients at diagnosis and after 12 months of TKI nilotinib to investigate molecular signatures characterizing both conditions. METHODS:We selected and counted BM CD34+/lin- cells of 30 CML patients at diagnosis and during 3, 6 and 12 months of first-line nilotinib treatment. GEP was performed between CD34+/lin- cells of patients at diagnosis and the same patients after 12 months of nilotinib. RESULTS: The number of BM CD34+/lin- cells dramatically decreased after 3, 6 and 12 months of nilotinib. GEP detected 264 statistically significant differentially expressed genes at diagnosis vs. 12 months of nilotinib. Functional enrichment analysis revealed groups of genes belonging to 14 pathways differentially active during nilotinib treatment. CONCLUSIONS: In conclusion, lipid, glucose and sphingolipid metabolism, insulin resistance, complement and coagulation, platelet activation, cytoscheleton, cell adhesion, transport, B cell differentiation, RAS-signaling pathway, proliferation, growth factors, and apoptosis were significantly deregulated between CML patients at diagnosis and after 12 months of nilotinib.

Chronic myeloid leukemia (CML) is characterized by the constitutive tyrosine kinase activity of the oncoprotein BCR-ABL1 in myeloid progenitor cells that activates multiple signal transduction pathways leading to the leukemic phenotype. The tyrosine-kinase inhibitor (TKI) nilotinib inhibits the tyrosine kinase activity of BCR-ABL1 in CML patients. Despite the success of nilotinib treatment in patients with chronic-phase (CP) CML, a population of Philadelphia-positive (Ph+) quiescent stem cells escapes the drug activity and can lead to drug resistance. The molecular mechanism by which these quiescent cells remain insensitive is poorly understood. The aim of this study was to compare the gene expression profiling (GEP) of bone marrow (BM) CD34+/lin- cells from CP-CML patients at diagnosis and after 12 months of nilotinib treatment by microarray, in order to identify gene expression changes and the dysregulation of pathways due to nilotinib action. We selected BM CD34+/lin- cells from 78 CP-CML patients at diagnosis and after 12 months of first-line nilotinib therapy and microarray analysis was performed. GEP bioinformatic analyses identified 2,959 differently expressed probes and functional clustering determined some significantly enriched pathways between diagnosis and 12 months of nilotinib treatment. Among these pathways, we observed the under expression of 26 genes encoding proteins belonging to the cell cycle after 12 months of nilotinib treatment which led to the up-regulation of chromosome replication, cell proliferation, DNA replication, and DNA damage checkpoint at diagnosis. We demonstrated the under expression of the ATP-binding cassette (ABC) transporters ABCC4, ABCC5, and ABCD3 encoding proteins which pumped drugs out of the cells after 12 months of nilotinib. Moreover, GEP data demonstrated the deregulation of genes involved in the JAK-STAT signaling pathway. The down-regulation of JAK2, IL7, STAM, PIK3CA, PTPN11, RAF1, and SOS1 key genes after 12 months of nilotinib could demonstrate the up-regulation of cell cycle, proliferation and differentiation via MAPK and PI3K-AKT signaling pathways at diagnosis.

In the PhilosoPhi34 study (EudraCT: 2012-005062-34) on 87 CP-CML patients, we analyzed the gene expression profiling (GEP) of bone marrow (BM) CD34+/lin- cells of 79 patients with chronic-phase chronic myeloid leukemia (CP-CML) patients at diagnosis and after 12 months of nilotinib treatment (Pungolino et al. AM J Hematol. 2018). FISH analyses identified CD34+/lin- Ph+ cells in all 79 CML-CP patients at diagnosis. 78/79 patients achieved at least a complete cytogenetic response after 12 months of nilotinib whereas 1/79 patients relapsed at 12 months. No Ph+ nuclei were detected in 78/79 patients at 12 months. We have demonstrated that genes involved in the JAK-STAT signaling pathway, the cell cycle, and the ATP-binding cassette (ABC) transporters were significantly over expressed in patients at diagnosis compared to 12 months of nilotinib treatment (Trojani et al, PLoS One. 2019). In this preliminary study, we isolated BM CD34+/lin- cells from 9 healthy donors (CTRLs). We investigated the gene expression profiling of 79 CP-CML patients at diagnosis vs. the same patients after 12 months of nilotinib treatment (12 months) vs. 9 CTRLs using Affymetrix HTA 2.0. Data was preprocessed and normalized using RMA and ComBat. Selection of differentially expressed genes (DEg) was performed at diagnosis vs. 12 months of nilotinib vs. CTRLs, using Statistical Analysis for Microarrays (SAM) on 3 groups and a Benjamini Hochberg false discovey rate threshold of 5%, followed, for significance comparisons, by a pair-wise SAM test. We focused on 34 genes of the cell cycle and mitosis, 6 genes belonging to the JAK-STAT signaling pathway, and the ABC transporter gene ABCD3 which were significantly under expressed at diagnosis vs. 12 months of nilotinib vs. CRTLs (Tab.1). In the cell cycle, we found that ORC2, ORC4, ORC5, MCM6, and HDAC2 (G1 phase) were progressively significantly down regulated at diagnosis vs. 12 months vs. CTRLs. We noticed HDAC2 which showed the high fold changes of 2.89 and 4.29 in the comparison between 12 months vs. CTRLs and between diagnosis vs. CTRLs, respectively. This gene plays a crucial role in CML, as HDAC inhibitors treatment represent an effective strategy to target leukemic stem cells in CP-CML patients receiving tyrosine kinase inhibitors. CCNA2, CDK7, CDC6, DBF4 (S phase), WEE1, PRKDC, ATM, MDM2, CCNB1 (G2 phase), and TTK, MAD2L1, BUB1, BUB3, ANAPC4, CDC27, SMC3, YWHAE, and YWHAZ (M phase) were progressively down regulated at diagnosis vs. 12 months vs. CTRLs. Among them, SMC3, YWHAE and YWHAZ showed the following high fold changes in the comparison between 12 months vs. CTRLs and between diagnosis vs. CTRLs: 2.31 and 3.15, 2.59 and 3.94, 2.75 and 4.15, respectively. Notably, the proto-oncogene MDM2 which promotes the development of tumors by targeting p53, was progressively up regulated in CTRLs vs. 12 months vs. diagnosis. In the mitosis, we detected that 10 genes playing a crucial role in mitotic chromosome organization, were progressively under expressed at diagnosis vs. 12 months vs. CTRLs (Tab.1). Notably, CLAPS2, ZW10 and ANLN (hematopoietic cell differentiation) regulate the exit from mitosis. NDC80, SMC4, ZNF207, and NEK2 take part in the mitotic sister chromatid segregation whereas CENPE and SMC2 are mitotic cell cycle check points. In the JAK-STAT signaling pathway, SOS1, PIK3CA, IL7, JAK2, STAM, and PTPN11 were progressively up regulated in CTRLs vs. 12 months vs. diagnosis (Tab.1). ABCD3, encoding a protein which pumped drugs out of the cells, was progressively under expressed at diagnosis vs. 12 months vs. CRTLs as shown in Tab.1. In conclusion, we found progressive gene expression changes in BM CD34+/lin- cells of 79 CP-CML patients at diagnosis vs. 12 months of nilotinib vs. the normal cell counterparts of 9 CTRLs in the cell cycle, JAK-STAT, and the ABC transporter ABCD3. FISH analyses demonstrated that the BM CD34+/lin- cells of 78/79 patients after 12 months of nilotinib were Ph-negative. Despite, our GEP results suggested that BM CD34+/lin- cells after 12 months of nilotinib treatment and the normal cell counterparts differed mostly in the expression of genes regulating the cell cycle and the JAK-STAT signaling pathway. Disclosures Rossi: Daiichi-Sankyo: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Mundipharma: Honoraria; BMS: Honoraria; Sandoz: Honoraria. Elena:Novartis: Consultancy; Pfizer: Consultancy. Iurlo:Pfizer: Other: Speaker Honoraria; Incyte: Other: Speaker Honoraria; Novartis: Other: Speaker Honoraria.

Myeloproliferative neoplasms (MPNs) are clonal disorders that include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Patients with MPNs have a higher risk than the general population of developing a lymphoid neoplasm.1 It is still unclear whether this holds true for nonhematological second primary malignancies (SPMs).2-4 However, among 20 250 MPN patients included in the Surveillance, Epidemiology, and End Results (SEER) Program database, the 10-year cumulative incidence of SPMs was 12.7%, significantly higher than that expected in the general US population.5 Ruxolitinib (RUX) is an oral JAK inhibitor (JAKi) approved for International Prognostic Scoring System (IPSS)/Dynamic IPSS (DIPSS) intermediate- and high-risk myelofibrosis (MF)6,7 and for inadequately controlled PV. More than 2600 RUX-treated MF patients have been prospectively observed for at least 2 years within the 2 pivotal COMFORT trials8,9 and the expanded-access JUMP trial.10,11 Safety data from these trials underline a possibly increased incidence of nonmelanoma skin cancers (NMSCs), but no significant increase of lymphoproliferative neoplasms, similarly to what occurs in PV.12,13 Recently, Porpaczy et al alerted, however, on the possible 16-fold increased risk of developing aggressive lymphomas in MPN patients treated with JAKis, especially in the presence of a preexisting B-cell clone.14 The publication included a total of 1555 MPN patients, 126 of whom were treated with a JAKi (ruxolitinib, gandotinib, fedratinib, momelotinib), obtained assembling 2 broad academic data sets. In the well-described Viennese cohort, 3 of 31 MF patients treated with JAKi developed lymphomas. Median time from JAKi initiation to lymphoma diagnosis was 25 months. Subsequent analyses of other large academic data sets did, however, not confirm an increased risk of aggressive lymphoma development under JAKis in MPNs15,16 and in post-PV and post-ET MF (secondary MF [SMF]).17 These contradictory results were derived either from clinical trials with strict eligibility criteria, possibly at the expense of uncertainty about the generalizability of results, or from highly selected data sets of patients evaluated at referral centers, thus highlighting the need for real-world data (RWD). We consequently set out to assess the occurrence of SPMs, including lymphoproliferative neoplasms, in RUX-treated MF patients on the basis of RWD provided by the health authority of the Lombardy Region, integrated with institutional data.

Background Chronic Myeloid Leukemia (CML) is a clonal myeloproliferative disorder which molecular base is represented by the bcr-abl fusion gene, encoding for the constitutionally activated BCR-ABL tirosine-kinase. Three Tirosin-Kinase Inhibitors (TKI) are approved for first line treatment: Imatinib (IM) and the second generation (2G) TKI Nilotinib (NIL) and Dasatinib. 2G TKI are known to provide faster and deeper molecular responses (MR) compared to Imatinib, but serious toxicities may hamper long term treatment with these molecules. Furthermore, 2G TKI were usually employed as second line after IM failure, while the inverse sequence from second to first generation TKI (like an induction-maintenance model) has not been explored yet. We used this schedule in a small group of patients in the PhilosoPhi34 study (EudraCT: 2012-005062-34), a clinical trial designed by the REL (Rete Ematologica Lombarda) cooperative group. This study was composed by three consecutive phases: a Recruitment Phase, a Core Phase (CP) in which patients received NIL 300 mg BID for 12 month (mos), and an Observational Phase (OP), restricted for patients who obtained at least complete cytogenetic response at the end of the CP. During OP, treatment choice was up to the physician and any TKI approved for first line treatment could be used, including IM. In 2017 we presented preliminary data showing that a 12-mos-NIL treatment followed by IM appears as a safe and effective choice for first line therapy in chronic phase CML. Fluctuations in BCR/ABL ratio were similar between IM and NIL treated pts, and the probability of loss of MR4 or MR3 was the same in the two groups; furthermore, despite fluctuations, MR was maintained or improved over time in IM subgroup. Our purpose is to verify these data after 24 mos follow up (FU) at the end of OP. Methods We analyze PhilosoPhi34 database; MR is reported at 3, 6 and 12 mos during the CP and every 6 mos during the OP. The last pt completed the 24 mos of OP in June 2018. Database is still open, evaluations ongoing, and some data can be missing yet: our preliminary observations concern pts with available data of 24 mos OP. Results Seventy-nine pts started the OP. Fourteen pts switched to IM during the OP (Table 1) due to high cardiovascular risk or grade 1-2 chronic AEs . Only 11 pts started IM since the beginning of OP, and we consider these pts in our analysis. Sokal score was high in 2 pts (18%), intermediate in 5 (45.5%), low in 4 (36.5%). At the beginning of OP, 6 pts had a MR ≥ 4 (54.5%), 5 had MR3 (45.5%). At 12 mos of the OP, 7 had MR ≥ 4, 3 had MR3 and 1 had lost MR3 with PCR 0.192%IS (1/5, 20%). At 24 mos of the OP, 9 had MR ≥ 4 (81,8%), and 2 had MR3. Notably, none of pts lost MMR; 2/3 pts(66%) improved response from MR 3 to MR 4 and the pt who transiently lost MMR at 12 mos, recovered it at 24. Sixty-four pts maintained 2G TKI: 62 NIL, 2 other TKI (not considered for analysis). Of them, 4 were lost during this phase: 2 within the first year of OP, other 2 within 12 and 24 mos of OP. In the NIL group, Sokal score was high in 10 pts (16.6%), intermediate in 19 (31.6%) and low in 31 (51.6%). At the beginning of OP, 32 pts had MR ≥ 4 (51.6%), 21 had MR3 (33.8%) and 9 less than MR 3 (14.5%). Responses were improved over time: at 12 mos, 36 pts had MR ≥ 4 (60%), 20 had MR3 (33%) and 4 less than MR3 (6%). At 24 mos 46 pts had MR ≥ 4 (78%), 8 MR3 (13.5%) and 4 less than MR3 (8,5%), Among them, 1 pt experienced disease progression due to a mutation. In particular, during the second year of OP, 11 pts improved response from MR3 to MR ≥ 4(11/20, 55%). Discussion Our data show progressive MR improvement in both IM and NIL group. In particular, risk of loss of MMR is not increased in IM group. More data, more balanced groups and a longer FU are necessary to further confirmations, but after three years of FU, we consider this combination of NIL-followed-by-IM a possible strategy for first line treatment in chronic phase CML, in particular for pts with cardiovascular risk factors. Disclosures Rossi: Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Gilead: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Honoraria; BMS: Honoraria; Sandoz: Honoraria; Pfizer: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

The study analyzed 30 chronic phase CML patients at diagnosis and at 3, 6 and 12 months of first-line nilotinib treatment. As optimal molecular response was achieved at 3, 6 and 12 months after nilotinib in all the 30 patients (figure 1), we established cut off values of molecular response (MR) to define groups of CML patients (n =30), and to investigate differences of gene expression profiles between patients at diagnosis based on the MR achieved after 3, 6 and 12 months of nilotinib, respectively. We used the following cut off values: 1% IS at 3 months of nilotinib, 0.1% IS at 6 months of nilotinib, and 0.01% IS at 12 months of nilotinib. Patients were divided into 2 groups based on MR values of each patient at 3 months of nilotinib: group A (n =24) with MR ≤1.0% IS and group B (n =6) with MR >1% IS. Based on the values of MR at 6 months of nilotinib, patients were divided into 2 groups: group C (n =22) with MR ≤0.1% IS and group D (n =8) with MR >0.1% IS. At 12 months of nilotinib, patients were divided into the following groups: group E (n =18) with MR ≤0.01% IS and group F (n =12) with MR >0.01% IS. Gene expression profiling (GEP) on the selected bone marrow (BM) CD34+/lin- cells of 30 CML patients at diagnosis was performed using Affymetrix GeneChip HTA 2.0. GEP data was preprocesses using RMA. SAMR and GSEA were used to detect differentially expressed genes and pathways (i.e. MSigDB Canonical pathways and GOBP gene sets) associated with the different groups, respectively. In both cases, correction for multiple testing was performed using the false discovery rate procedure with a threshold 0.05 for SAMR and 0.25 for GSEA as suggested by the software developers. GSEA detected significant differences in the transcriptional signature between group A and group B associated with the MR at 3 months as well as between group C and group D in respect to the MR at 6 months of nilotinib, whereas no genes were identified as significantly differentially expressed. Based on the MR at 3 months, we identified Reactome pathways "P130 cascade" and "GRB2 SOS linkage to MAPK signaling for integrins" significantly upregulated in group A compared to group B. FGA, FGB, FGG, APBB1IP, ITGA2B and CRK genes contributed to call the pathways upregulated. In vitro studies (Ding J et al. PloS One, 2013) demonstrated that nilotinib induced dephosphorilation of the BCR-ABL1 target CRK oncogene which acts in the CML hematopoietic stem cells like an adaptor in diverse signaling pathways and cellular processes playing an apoptotic role in CML. Our GEP results highlighted that the Reactome pathway involved in MAPK signaling (CRK gene) wasover expressed in CML patients with a better MR ≤1% IS at 3 months of nilotinib. Pathway "aminoacid and amine transport across the plasma membrane" was also significantly over expressed, whereas "lipid metabolism" was significantly down regulated (genes AKR1C1 and ANGPTL3) in group A compared to group B, respectively. Based on the MR at 6 months, GEP results showed that "positive regulation of cytokine secretion" and "interleukin 1 secretion" were significantly upregulated in group C compared to group D, involving PYCARD8, NLRP2, NLRC4, NLRP3 and CARD8 genes. Of note, PYCARD and CARD8 represent key mediators, which promote caspase-mediated apoptosis processes involving the recruitment of certain recognition receptors, such as NLRP2, NLRP3 and NLRC4. In addition, CARD8 and PYCARD promote apoptosis inhibiting NFKB activation. In conclusion, the study showed that MAPK signaling for integrins and amine transport across the plasma membrane were significantly over expressed in CML patients with a MR ≤1.0% IS while lipid metabolism was significantly over expressed in CML patients with a MR >1% IS after 3 months of nilotinib. After 6 months of nilotinib, positive regulation of cytokine secretion and interleukin 1 secretion were significantly over expressed in CML patients with a MR ≤0.1 IS compared to patients with a MR >0.1% IS. We identified distinct sets of genes involved in apoptotic processes differentially expressed in 30 CML patients based on the MR at 3 months as well as 6 months of first-line nilotinib treatment. Studies in a larger cohort of CML patients are ongoing to define the expression, role and functions of the genes regulating apoptosis CRK, PYCARD and CARD8 as candidate prognostic factors for molecular response to first-line nilotinib treatment. Disclosures No relevant conflicts of interest to declare.

Background. Chronic Myeloid Leukaemia (CML) can be effectively treated with the first generation Tyrosine Kinase Inhibitor (TKI) Imatinib, and more effectively with the second generation TKI, like Nilotinib. However, despite the deeper and faster responses induced by nilotinib in a large proportion of patients, the possible eradication of the pathological stem cells is not yet clearly elucidated. In fact, in vitro data suggest that quiescent stem cells are not sensitive to Bcr/Abl inhibition (Corbin AS, et al 2011; Hamilton A, et al 2012). A preliminary in-vivo study (Defina M, et al 2012) shows that in patients in CCyR even after short-term of nilotinib therapy, residual leukemic progenitors are rarely detected. Methods. On behalf of Rete Ematologica Lombarda (REL), Italy, we designed a single arm prospectic study, PhilosoPhi34 (EudraCT: 2012-005062-34), with the aim to investigate the efficacy of nilotinib 300 mg BID in obtaining the disappearance of Bone Marrow (BM) leukemic stem cells (CD34+/lin-Ph+) in newly diagnosed CP-CML. Primary objective of the study: to enumerate the BM CD34+/lin-Ph+ cells at the end of 6 months of treatment. Secondary objectives: to enumerate the BM CD34+/lin-Ph+ cells at 3 and 12 months; to assess the percentage of patients showing MR ≤10% IS at 3 months and MR ≤1% IS at 6 months and the MMR IS and MR4.5 IS by 3, 6 and 12 months of treatment. BM blood samples (range of 5-20 ml) were collected at diagnosis and after 3, 6 and 12 months of nilotinib treatment. BM mononuclear cells were purified by density gradient centrifugation and then CD34+/lin- cells were isolated using Diamond CD34 Isolation Kit (Miltenyi Biotec). The purity of CD34+/lin- cells was about 97% as determined by flow cytometry. BM CD34+/lin- cells were counted and a range of 100,000-800,000 has been noted at diagnosis. After the treatment we observed that the number of CD34+/lin- cells dramatically decreased after 3 (1,000-600,000), 6 (1,000-260,000) and 12 months (100-130,000). In particular, CD34+/lin- cells were even less than 1000 at 12 month of treatment. In order to verify the disappearance of leukemic stem cells, isolated CD34+/lin- cells were tested by standard FISH (i.e. to categorize a sample as negative at least 200 nucleus were examined). From April 2013 and June 2015 we enrolled 87 pts, as for protocol. We report here the preliminary results. Results. Of 56 patients in CCyR after 6 months of treatment, FISH performed on BM CD34+/lin- cells nuclei was evaluable in 51 cases (5 negative cases were excluded because of less than 200 nucleus were analysed). In 4 out of 51 patients (7.8%), Ph+ nuclei were detected. The Sokal score of these 4 patients was 1 low, 2 intermediate and 1 high risk with a ratio (positive nuclei/total nuclei) of 295/300, 1/200, 2/92, 3/300, respectively. Among 58 patients tested at 3 months and 44 tested at 12 months of treatment, the number of evaluable patients was 48 and 37, respectively; 8/48 (16.6%) and 0/37 (0%) patients showed Ph+ nuclei. Only 2 out of 8 positive patients had a high Sokal score. Regarding efficacy of treatment, Table 1 summarizes the MRs IS observed after 3, 6 and 12 months of treatment in 71, 57 and 41 patients, respectively. Conclusion. Data of this prospective study confirms that nilotinib 300 mg BID, rapidly and progressively induces the clearance of BM CD34+/lin-Ph+ cells in CP-CML patients. In particular, on CD34+/lin- cells, after 6 months of treatment, only 7.8% of patients showed positive nuclei. On 37 patients after 12 months of treatment, no positive nuclei were detected. So far, the kinetic of reduction of such cells seems not influenced by Sokal score. According to international studies, PhilosoPhi34 shows a very high efficacy of Nilotinib to induce MRs in CP-CML patients, at the standard time points. Table 1. Molecular Response (MR) in CP-CML patients treated with Nilotinib 300mg BID from diagnosis. MR IS 3 months 6 months 12 months ≤10% 67/71 94% 57/57 100% 40/41 97.50% ≤1% 57/71 80% 55/57 96.50% 40/41 97.50% ≤0.1% 17/71 24% 41/57 72% 35/41 85% ≤0.01% 3/71 4% 19/57 33% 20/41 48.70% MR4.5(UD) 2/71 2.80% 10 (6)/57 17.5% (10.5%) 15 (9)/41 36.5% (22%) UD: undetectable We acknowledge all REL Colleagues for their collaboration and Novartis SpA for the partial financial support to the study. Disclosures No relevant conflicts of interest to declare.

Background CML is a clonal disorder characterized by the presence of the Philadelphia (Ph) chromosome which encodes for the bcr-abl tyrosine-kinase (TK). Target therapy with the TK inhibitors (TKIs)) has greatly improved its outcome. Treatment with second generation TKIs - e.g. nilotinib (NIL) - results in deeper and faster responses and prevents disease progression. Sustained responses may enable TKI discontinuation. However, even in the event of qPCR negativity, a fraction of patients (pts) experience disease recurrence possibly due to persistence of quiescent leukemic stem cells (LSCs). Degree and mechanisms of LSCs clearance during TKI treatment are not established yet and conflicting results are reported in the literature. Work from the group of Bocchia (Bocchia 2008; Defina 2012) showed reduction of LSCs during long term imatinib (IM) therapy; moreover, in CCyR pts residual LSCs are more rarely detected after NIL compared to IM therapy and, in a small fraction of pts this occurs after very short-term NIL therapy. This data conflicts with in vitro evidence that NIL is not superior to IM in inducing growth suppression in CML LSCs (Konig, 2008). To verify the in vivo activity and time-course of first-line NIL therapy on bone marrow (BM) Ph+ stem cells (CD34+/lin-) clearance, on behalf of the Rete Ematologica Lombarda (REL) the PhilosoPhi34 study (EudraCT: 2012-005062-34) was designed. Primary efficacy endpoint was to measure the rate of BM residual CD34+/lin-Ph+ cells in CCyR pts at 6 months of treatment. Methods BM cells were collected and stored at diagnosis and at 3,6 and 12 mos of treatment. CD34+/lin- cells were purified using a Diamond CD34 Isolation Kit Miltenyi (97% of purity). FISH analysis of selected unstimulated CD34+/lin- cells was performed according to standard procedures; considering the low sensitivity of the test, in order to define the test as negative at least 200 nuclei were examined. The A'Hern single stage design was chosen for the present study; considering the CCyR results obtained in the ENESTnd study and the anticipated number of un-evaluable tests, a minimun of 87 pts were required. Results Enrolment of the 87 pts was completed by June 2015. Table 1 summarises pts' characteristics and response to treatment. FISH results are as follows: at 3 mos, 8/65 (12,3%; CI 95%: 2,3%-15,7%) evaluable FISH tested positive (10 negative tests not evaluable); at 6 mos 5/71 (7%; CI 95% :2,3-15,7%) evaluable FISH tested positive (7 negative tests not evaluable); at 12 mos, 0/68 (0%; CI95%:0,0-5,2%) evaluable FISH tested positive (9 negative tests not evaluable). At any time point, Sokal score did not predict for FISH results. However, as outlined in Table 2, H-Sokal score pts are less prevalent among pts who achieve a CCyR, a requirement for FISH analysis. Of the 4 pts who failed the treatments' objectives by 12 mos, 1 was in CCyR with detectable residual CD34+/lin-Ph+ cells at 3 mos; 2 were not in CCyR and with residual CD34+/lin-Ph+ cells at 3mos; 1 was in CCyR and with CD34+/lin-Ph- cells at 3 and 6 mos but with increasing qPCR. Only 1 pt with CD34+/lin-Ph- cells at all time points and with optimal molecular response harboured a NIL-resistant mutation at 26 mos of treatment. None of the 22 pts (including 4 H-Sokal score pts = equal proportion of study cohort) in Molecular Response (MR) 3.0 at 3 mos had a positive FISH at 3 and 6 mos or failed treatment at follow-up. Conclusion. Our final results on the whole cohort of pts confirm our preliminary data on the efficacy of NIL 300 g BID in early clearance of BM LSCs (CD34+/lin-Ph+) in newly diagnosed CP-CML patients tested at 3, 6 and 12 mos of treatment. Moreover, according to our data, fast disease debulking seems crucial for obtaining BM LSCs clearance and it can be speculated that the same mechanism responsible for this early MR 3.0 achievement is also capable of preventing H-Sokal risk pts from failing treatment. Disclosures Orlandi: Ariad: Honoraria; BMS: Honoraria; Novartis: Honoraria.

A 43 year-old woman presented with fever, abdominal pain, epato-splenomegaly, ascites, cholestasis, anemia, thrombocytopenia and previous diagnosis of sclerosing cholangitis based on liver biopsy and endoscopic retrograde cholangiopancreatography(ERCP). The bone marrow biopsy and the revision of liver biopsy using antitryptase stain diagnosed systemic mastocytosis. Because of the aggressive course of the disease the patient was treated with an acute myeloid leukaemia chemotherapy regimen without success.

The incidence of invasive filamentous fungal infections in hematologic patients is increasing as a consequence of high dose chemotherapy and bone marrow transplant procedures. Mortality is usually very high. The diagnosis is often difficult and yet a fast, accurate diagnosis is of fundamental importance for treating the infection and planning subsequent management of the hematologic disease. We evaluated the sensitivity of computed tomography (CT)-guided percutaneous biopsy in diagnosing pulmonary fungal infections.Between 1997 and 2002 we performed 17 CT-guided percutaneous transthoracic lung biopsies in 17 hematologic patients with suspected filamentous fungi infection with negative BAL, to obtain a certain diagnosis and to know what species of fungi was responsible for infection. In all cases suspected mycosis began during the post-chemotherapy aplastic period. Patients were receiving antifungal therapy at the time of all biopsies. When the platelet count rose above 50 x 10(9)/L, CT-guided percutaneous lung biopsy with fine-needle aspiration for cytology was performed.Twelve of 17 patients had histologic confirmation of the fungal infection (70.5%), 8 with Aspergillus spp. 4 with Mucorales spp. Biopsies provided non-specific results in 4 cases; in 2 of these cases, clinical course and response to therapy confirmed the diagnosis of mycosis; in the last case bronchoalveolar carcinoma was found as a new diagnosis. Cultures were positive in only 6 cases, all for Aspergillus spp. The sensitivity of CT-guided percutaneous lung biopsy was 70.6% and its positive predictive value (PPV) was 100%. This procedure provided an immediate diagnosis and only one side-effect (1 pneumothorax, without complications).Histologic discrimination between aspergillosis and mucormycosis is very important for deciding secondary prophylaxis during transplant procedures, because Mucor is usually resistant to azoles.