Abstract: The e13a2 and the e14a2 are the most frequent BCR-ABL1 transcripts in chronic myeloid leukemia (CML) patients. The aim of the present study was to assess the prognostic value of the e13a2 (b2a2) or the e14a2 (b3a2) fusion transcripts on the long-term outcome of early chronic phase (ECP) CML patients treated frontline with imatinib mesylate (IM). Few studies, mostly based on a small number of patients or with a relatively short observation, have been published, particularly in ECP setting. Due to partially conflicting data, the transcript type is not actually considered an established baseline prognostic factor. To our knowledge, this is the first long-term analysis conducted in the context of large prospective studies. Methods A retrospective analysis of 3 GIMEMA CML WP prospective clinical studies (NCT00514488, NCT00510926, observational study CML/023) was performed. All the 559 enrolled patients were analyzed. A qualitative RT-PCR for BCR-ABL1 transcript was routinely performed at enrollment. Patients expressing rare transcripts or with both e13a2-e14a2 transcripts were excluded: 493 out of 559 patients were included, 203 (41%) with e13a2 transcript and 290 with e14a2 transcript (59%). Definitions. Major molecular response (MMR): BCR-ABL1IS ratio 〈 0.1%. Deep molecular response (MR4.0): detectable disease ≤ 0.01% BCR-ABL1IS or undetectable disease with ≥10,000 ABL1 transcripts. Progression: transformation to accelerated or blastic phase. Failure: according to 2013 ELN recommendations. Event: failure or permanent discontinuation for any reasons. All the deaths, at any time and for any reasons, were included. Results The median follow-up was 76 months; 95% of the patients had at least a 5-year observation. The 2 groups were comparable for demographic and hematologic characteristics, except for the proportion of male patients, that was higher in the e13a2 group (p = 0.05), and for the baseline percentages of eosinophils, that was lower in the e13a2 group (p = 0.009). The Sokal, Hasford and EUTOS risk score distributions and the proportion of patients with CCA in Ph+ cells were comparable. The complete cytogenetic response (CCyR) rate at 12 month was not significantly different (75% and 79% in e13a2 e14a2 patients, respectively, p=0.274), but the MMR rate at 18 months and the MR4.0 at 36 months were significantly lower in e13a2 patients (52% and 67%, p = 0.001; 20% and 30%, p = 0.013, respectively). As far as the rapidity of response, the time to MMR and the time to MR4 were significantly slower for patients with e13a2 transcript (12 and 6 months; 54 and 37 months, respectively), with an inferior overall estimated probability of MMR (85% and 92%, p 〈 0.001) and MR4 (57% and 71%, p = 0.002). The overall survival (83% and 86%, p = 0.023), the progression-free survival (81% and 86%, p = 0.007), the failure-free survival (54% and 71%, p 〈 0.001) and the event-free survival (46% and 61%, p = 0.003) were significantly lower in patients with e13a2 transcript (figure 1). In a multivariate analysis (Cox model), the transcript type retained its prognostic significance, when adjusted for other relevant variables. Analyzing separately the patients treated with IM 400 mg (n = 371; e13a2 and e14a2 transcript: 208 and 163 patients, respectively) or IM 800 mg (n = 122; e13a2 and e14a2 transcript: 82 and 40 patients, respectively), all the above mentioned response and outcome differences were confirmed, with one exception: in the high-dose IM group the overall survival probability was inferior for the e13a2 patients, but, probably due to the small number of patients, the difference was not statistically significant (83% and 86%, p = 0.268). Conclusions A long-term analysis in a large cohort of CML patients suggests that the e13a2 transcript is an adverse prognostic factor in ECP CML patients treated frontline with IM. An independent evaluation is required for confirmation. Acknowledgments University of Bologna, BolognaAIL, COFIN, Fondazione Carisbo. Disclosures: Castagnetti: Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Gugliotta:Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria. Abruzzese:BMS, Novartis: Consultancy.

Abstract: Abstract 2294 Background. The TKIs Nilotinib and Dasatinib offer additional therapeutic options for patients with CML who are resistant or intolerant to Imatinib. These agents, active against the majority of Imatinib resistant BCR-ABL mutated clones, have a different pattern of kinase target selectivity, pharmacokinetics parameters, cell uptake, efflux properties and adverse events profiles. Preliminary results suggest that some patients may respond to a second TKI used as third line therapy, but little is known about the long term benefit of such an approach.Aim of this collaborative Italian study was to verify the response (rate and duration) and the clinical outcome in patients with CML treated with a third TKI after sequential failure of the previous ones. Methods. We evaluated 66 patients with CML, resistant/intolerant to Imatinib and treated with Dasatinib or Nilotinib, then switched to a third- line TKI after treatment failure. Of these, 29 patients were treated with dasatinib after imatinib/nilotinib failure and 37 with nilotinib after imatinib/dasatinib failure. Patients were monitored with complete blood counts, cytogenetic analysis, bone marrow aspiration RT-PCR and mutational analysis. Results. A total of 66 patients (median age 63 years, range, 33–85 years) were treated with sequential TKIs; 40 (61%) patients had received interferon-a before starting Imatinib; 26 (39%) patients received imatinib as first line therapy. The median time on imatinib therapy was 47.5 months (range 4–101 months). At the start of nilotinib as second line, 27/29 (93%) patients were in CP, 1 (3.5%) in AP, and 1 (3.5%) in BP. 9 patients (31%) had developed mutations before starting treatment. The median time on second line TKI was 8 months (range 2–36 months). In the resistant patients 4 new mutations were identified (F359V in two patients, T315I, Y253H+F359V). At the start of dasatinib as second line, 33/37 (89.2%) patients were in CP, 4 (10.8%) in AP. 7 patients (18.9%) had developed mutations before starting treatment. The median time on second line TKI was 14 months (range 4–59 months).In the resistant patients 5 new mutations were identified (F137L in three pts, M318T, M244V+F317L). At the start of the third TKI, 60/66 (90.9%) patients were in CP, 5 (7.6%) in AP, and 1 (1.5%) in BP. Of these, 7 patients (18.9%) on dasatinib and 7 (24.1%) on nilotinib had mutations before starting treatment. The best response to the third line treatment with TKI was 10 (15.2%) MMR, 10 (15.2%) CCyR, 8 PcyR (12.1%), 5 (7.5%) mCyR, 24 (36.4%) CHR and 9 (13.6%) No Response (NR). In the dasatinib group, 9 (31%) patients discontinued treatment because of toxicity versus 17 (45.9%) patients in the nilotinib group.Two new mutations (F317L, E255V) emerged with dasatinib as third line therapy.After a median follow up of 13 months (range 2–37 months) 50 patients (48 CP, 2 AP) are continuing therapy (33 on nilotinib, 17 on dasatinib).Since the start of the third TKI, 61 patients (92.4%) are still alive for a median overall survival of 110 months (range 15–300) (52 CP, 7 AP, 2 NA); the 5 deaths (7.6%) were caused by disease progression and spread of the gene mutation T315I. Discussion. In our study, about one third of patients derived benefit from the use of three sequential TKIs; patients with better, longer response (28.7%) to third TKI were the same patients with a better response to the Imatinib and 2TKIs therapy. All these patients had taken interferon therapy before the Imatinib. In this subset of patients (good responders: CCyR and MMR) 5 patients developed mutations that were sensitive to the sequential treatment.The lack of a durable cytogenetic remission could be explained by the emergence of new kinase domain mutations as patients are exposed to sequential TKI; a change of therapy resulted in an adequate response. In our series, patients with poor prognosis showed mutations not sensitive to the TKIs treatment. Conclusions. Although allogeneic SCT is the treatment of choice in all patients failing 2 TKIs who are suitable candidates for this approach, alternative strategies are required for ineligible patients. The use of a third TKI after failure of two previous TKIs induces response in some patients. Longer follow up of a larger series of patients is needed to determine the long term impact of the response. Disclosures: No relevant conflicts of interest to declare.

Abstract: The most frequent BCR‐ABL1 fusion transcripts in chronic myeloid leukemia (CML) are the e13a2 (b2a2) and the e14a2 (b3a2) ones. In the imatinib era few studies addressing the prognostic significance of the BCR‐ABL1 transcript type in early chronic phase CML have been published. Overall, these studies suggest that in e14a2 patients the response to imatinib is faster and deeper. To evaluate if the BCR‐ABL1 transcript type (e13a2 compared to e14a2) affect the response to imatinib and the clinical outcome in newly diagnosed adult CML patients, 559 patients enrolled in 3 prospective studies (NCT00514488, NCT00510926, observational study CML/023) were analyzed. A qualitative PCR was performed at baseline: 52% patients had a e14a2 transcript, 37% a e13a2 transcript, 11% co‐expressed both transcripts and 1% had other rare transcripts. The median follow‐up was 76 months (95% of the patients had at least a 5‐year observation). The complete cytogenetic response rates were comparable in e14a2 and e13a2 patients. The median time to MR 3.0 (6 and 12 months) and MR 4.0 (41 and 61 months) was significantly shorter for e14a2 patients compared to e13a2 patients, with a higher cumulative probability of MR 3.0 (88% and 83%, P   〈  .001) and MR 4.0 (67% and 52%, P  = .001). The 7‐year overall survival (90% and 83%, P  = .017), progression‐free survival (89% and 81%, P  = .005) and failure‐free survival (71% and 54%, P   〈  .001) were significantly better in patients with e14a2 transcript. In conclusion, patients with e13a2 transcript had a slower molecular response with inferior response rates to imatinib and a poorer long‐term outcome.

Abstract: Several papers authored by international experts have proposed recommendations on the management of BCR-ABL1+ chronic myeloid leukemia (CML). Following these recommendations, survival of CML patients has become very close to normal. The next, ambitious, step is to bring as many patients as possible into a condition of treatment-free remission (TFR). The Gruppo Italiano Malattie EMatologiche dell’Adulto (GIMEMA; Italian Group for Hematologic Diseases of the Adult) CML Working Party (WP) has developed a project aimed at selecting the treatment policies that may increase the probability of TFR, taking into account 4 variables: the need for TFR, the tyrosine kinase inhibitors (TKIs), the characteristics of leukemia, and the patient. A Delphi-like method was used to reach a consensus among the representatives of 50 centers of the CML WP. A consensus was reached on the assessment of disease risk (EUTOS Long Term Survival [ELTS] score), on the definition of the most appropriate age boundaries for the choice of first-line treatment, on the choice of the TKI for first-line treatment, and on the definition of the responses that do not require a change of the TKI (BCR-ABL1 ≤10% at 3 months, ≤1% at 6 months, ≤0.1% at 12 months, ≤0.01% at 24 months), and of the responses that require a change of the TKI, when the goal is TFR (BCR-ABL1 & gt;10% at 3 and 6 months, & gt;1% at 12 months, and & gt;0.1% at 24 months). These suggestions may help optimize the treatment strategy for TFR.

Abstract: To assess the most important features and clinical impact of pleural effusions, which are a common toxicity during dasatinib treatment and often impair its high efficacy, 172 unselected consecutive patients with chronic myelogenous leukaemia in chronic phase treated in 27 Italian centres, with dasatinib when aged 〉 60 years for resistance/intolerance to imatinib, were examined. During treatment, 52/172 patients (30.2%) presented pleural effusion, which was grades 1–2 in 38 patients and grades 3–4 in 14 patients (8.1% of the entire cohort of patients), according to the WHO scale; in 14/52 patients (26.9%), there was a concomitant pericardial effusion. Pleural effusion was recurrent in 25/52 patients (48.0%). Median time from dasatinib to first pleural effusion was 11.0 months (interquartile range 3.6–18.6). Eleven patients (6.4%) required permanent dasatinib discontinuation. Only presence of concomitant pulmonary disease ( p = 0.035) and initial daily dose of dasatinib (140 mg vs 100 mg, p = 0.014) were significantly associated with pleural effusions. There were no differences among patients with or without pleural effusions as concerns response rates and overall survival. Pleural effusions were common in our unselected ‘real‐life’ population of elderly patients but were clinically manageable and did not seem to affect treatment results. Copyright © 2012 John Wiley & Sons, Ltd.

Abstract: Background: The presence of peripheral blasts (PB) is a negative prognostic factor in patients (pts) with primary and secondary myelofibrosis (PMF/SMF) and PB ≥4% was associated with a particularly unfavorable prognosis (Masarova L et al, Cancer 2020). Ruxolitinib (RUX) is the JAK1/2 inhibitor most used for treatment of MF-related splenomegaly and symptoms. Its role has not been assessed in correlation with PB. Aims: To evaluate the impact of PB percentage on RUX efficacy and prognosis Methods: After IRB approval, the "RUX-MF" retrospective study collected 804 RUX-treated chronic-phase (CP, defined as PB & lt;10%) pts in 26 Hematology Centers. In 794 pts, PB count was evaluated by morphology at RUX start and correlated with treatment success and outcome. Risk category was assessed according to DIPSS (Passamonti F et al, Blood. 2010). Spleen (SR) and symptoms (SyR) response were assessed using IWG-MRT criteria (Tefferi A et al, Blood. 2013). Comparisons of quantitative variables between the 3 groups were carried out by Kruskal-Wallis and Dunn's tests while association between categorical variables was tested by the χ2 test. Variables significantly associated to RUX stop/leukemic transformation (LT)/overall survival (OS) in univariate analysis (Log-rank test) were considered for multivariable analyses, carried out using the Cox regression model, with evaluation of the model's performance in terms of goodness of fit. Results: Pts were categorized according to PB at RUX start: PB-0 (no PB; n. 487, 61.3%), PB-5 (PB 1-5%; n. 283, 35.8%), and PB-9 (PB 6-9%; n. 24, 2.9%). Pts characteristics at RUX start were: median age 68.1y (24-89); males 58.1%; PMF 52.5%; JAK2, CALR and MPL mutated: 80.5%, 13.1% and 2% (4.4% triple negative), high DIPSS: 7.6%; PLT & lt;100/WBC & gt;25 x10 9/l: 10.8%/16.4%; spleen length ≥10 cm: 47.8%, TSS ≥20: 60.6%; ≥1/≥2 high-risk mutation (HMR): 69/18 out of 167 evaluable (41.3%/10.8%); fibrosis grade ≥2: 77.9%; starting/cumulative RUX dose ≥15 mg BID: 61.4%/52.6%. Higher PB count was associated to high DIPSS risk (PB-0: 1.9%, PB-5: 16.2%, PB-9: 21.7%, p & lt;0.001), PLT & lt;100 x10 9/l (PB-0: 17.6%, PB-5: 15.1%, PB-9: 26.1%, p & lt;0.001), fibrosis grade ≥2 (PB-0: 73.3%, PB-5: 84.2%, PB-9: 100%, p & lt;0.001), spleen length ≥10 cm (PB-0: 43%, PB-5: 55.1%, PB-9: 59.1%, p=0.003). At 3 and 6 mos, 26.9% and 30.4% of evaluable pts achieved a SR, while 59.7% and 68.1% were in SyR, respectively. At 3 mos, SR (PB-0: 31.8%, PB-5: 20.6%, PB-9: 10%, p=0.001) and SyR (PB-0: 62.9%, PB-5: 55.5%, PB-9: 36.8%, p=0.02) were less frequently achieved by PB-5 and PB-9 pts compared to PB-0 pts. This association remained significant for SR at 6 mos (PB-0: 35%, PB-5: 23.9%, PB-9: 14.3%, p=0.006) and for both SR (p=0.003) and SyR (p=0.01) at any time. After a median RUX exposure of 1.5 y (0.1-8.9), 491 (61.8%) pts stopped RUX, 110 (13.9%) had a LT and 365 (46%) died. In univariate analysis, at 2y PB-9 pts had higher rates of RUX stop (73.9% vs 40.8% and 34.3% in PB-5 and PB-0 pts, log-rank p & lt;0.001) and LT (38.5% vs 10.2% and 6.2% in PB-5 and PB-0 pts, log-rank p=0.003). Median survival times of PB-0, PB-5 and PB-9 patients were 5.8, 4.9 and 2 years, respectively (log-rank p & lt;0.001) (Figure 1). In multivariable analysis, PB-9 pts confirmed their association with: 1) RUX stop (HR 3.74, 95%CI 1.51-3.70, p & lt;0.001), with TSS & gt;20 (HR 1.66, 95%CI 1.05-2.61, p=0.03), and HMR≥2 (HR 2.69, 95%CI 1.26-4.47, p=0.007); 2) LT (HR 3.71, 95%CI 1.71-8.04, p & lt;0.001), with HMR≥2 (HR 7.10, 95%CI 2.28-22.1, p & lt;0.001); 3) OS (HR 2.40, 95%CI 1.60-3.60, p & lt;0.001), with age≥65 (HR 2.31, 95%CI 1.17-4.57, p=0.02) and HMR≥2 (HR 3.21, 95%CI 1.67-6.20, p & lt;0.001). Unfavorable association with LT and OS was confirmed also in patients with HMR≥1. Conclusions: CP-MF pts with PB & gt;5% have a worse response to RUX and a worse outcome. Personalized approaches beyond RUX monotherapy may be useful in this context. Further clinical trials evaluating combination strategies and new drugs are required. Figure 1 Figure 1. Disclosures Palandri: Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; AOP: Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Membership on an entity's Board of Directors or advisory committees; CTI: Consultancy. Abruzzese: Bristol Myers Squibb: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Iurlo: Bristol Myers Squibb: Speakers Bureau; Pfizer: Speakers Bureau; Novartis: Speakers Bureau; Incyte: Speakers Bureau. Bonifacio: Bristol Myers Squibb: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria. Cuneo: AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau. Pane: AbbVie; Amgen; Novartis: Other: Travel, accommodation, expenses; Novartis Pharma SAS;: Research Funding; AbbVie; Amgen; Novartis, GSK , Incyte: Consultancy; AbbVie; Amgen; Novartis, GSK, Incyte: Speakers Bureau. Lemoli: Celgene: Other: Support for attending meetings and/or travel; Jazz, Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie, Daiichi Sankyo, Servier: Honoraria, Speakers Bureau. Cavo: Bristol-Myers Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Speakers Bureau; Adaptive Biotechnologies: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Accommodations, Speakers Bureau; GlaxoSmithKline: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Breccia: Novartis: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; Bristol Myers Squibb/Celgene: Honoraria; Abbvie: Honoraria.

Abstract: In the current clinical practice, imatinib is widely used also in very elderly patients with chronic myeloid leukemia (CML) at different doses based on concomitant diseases and physician' judgment. However, data on long-term follow-up of these patients are still lacking. To address this issue, we revised in our retrospective database 233 CML patients aged ≥ 75 years and treated with imatinib frontline in 34 italian hematological centers from 2/2002 to 7/2014. Median age at diagnosis was 78.4 years [interquartile range (IQR) 76.3 - 81.3], there were 113 males (48.5%) and 120 females (51.5%), median WBC, Hb and PLT counts were 45.0 x 109/l (IQR 29.4 - 83.4), 12,4 g/dl (IQR 11.0 - 13.6) and 375 x 109/l (IQR 238 - 680), respectively. Sokal Risk at diagnosis was low in 1 patient (0.4%), intermediate in 149 (67.4%), high in 71 (32.2%) and not evaluable in 12. One or more concomitant diseases requiring specific treatments were present in 225/233 patients (96.5%). Median interval from diagnosis to imatinib start was 0.7 month (IQR 0.2 - 1.4): the initial imatinib dose was 400 mg/day in 161 patients (69.1%), 300 mg/day in 57 (24.5%) and 〈 300 mg/day in 15 (6.4%). According to WHO, a grade 3 - 4 hematological and extra-hematological toxicity was reported in 44 (18.8%) and 41 (17.6%) patients, respectively. As to cumulative response, 13 patients (5.6%) discontinued IM due to early toxicity, 4 (1.7%) were resistant and 2 (0.8%) died from unrelated cause early after IM initiation: the remaining 214 patients (91.9%) achieved a complete haematological response (CHR). Among these 214 patients in CHR, 13 refused any other karyotipic or molecular evaluation, 23 achieved CHR only and 178 (76.4% of all 233 patients) achieved a cytogenetic response (CyR), which was partial in 16 patients and complete (CCyR) in 162 (69.5% of all 233 patients). In addition, among the 162 patients in CCyR, 125 (53.6% of all 233 patients) achieved a molecular response (MolR) (ratio 〈 0.1). A blastic phase occurred in 11 patients (4.7%). After a median follow-up from imatinib start of 45.0 months (IQR 22.3 - 72.0), 70 patients have died (9 from disease progression and 61 from unrelated causes), 16 patients were lost to follow-up and 147 are still alive (115 of them still in treatment with imatinib): 5-year event-free survival (EFS) and overall survival (OS) were 51.4% (CI95% 43.9 - 58.9) and 68.5% (CI95% 61.2 - 75.8), respectively. At univariate analysis, only the initial dose of imatinib (400 vs ≤ 300, p=0.03) was a significant predictive factor for CCyR achievement while only PLT count ≤ 500 x 109/l (p=0.031) was a significant predictive factor for MolR achievement. At multivariate analysis for EFS, achievement of a MolR (OR 0.25, 95%CI 0.14 - 0.43, p 〈 0.001), achievement of a CCyR (OR 0.40, 95%CI 0.23 - 0.67, p=0.001) and spleen enlargement (OR 1.56, 95%CI 1.01 - 2.41, p=0.042) were independent prognostic factors; at multivariate analysis for OS, achievement of a MolR (OR 0.30, 95%CI 0.18 - 0.49, p 〈 0.001), age 〈 80 yrs (OR 0.53, 95%CI 0.33 - 0.86, p=0.011) and male gender (OR 1.80, 95%CI 1.11 - 2.91, p=0.016) were independent prognostic factors. In conclusion, the long term follow-up of very elderly CML patients who started imatinib is very good and justify any effort to treat these patients with standard doses, in order to achieve cytogenetic and molecular responses as in younger subjects. Disclosures Castagnetti: BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; ARIAD: Consultancy, Honoraria. Tiribelli:Ariad Pharmaceuticals: Consultancy, Speakers Bureau; Novartis Farma: Consultancy, Speakers Bureau; Bristol Myers Squibb: Consultancy, Speakers Bureau. Gugliotta:BMS: Honoraria; Novartis: Honoraria. Abruzzese:BMS, Novartis, Pfizer, Ariad: Consultancy.

Abstract: Tyrosine-kinase inhibitors (TKIs)have completely changed the expected survival of chronic myeloid leukemia (CML) patients which is now approaching that of the general population: a relevant proportion of CML patients are currently elderly or very elderly. Very elderly patients represent generally a small proportion in published experiences. Older CML patients imatinib treated, as it happens in the general population, receive other drug treatments for associated chronic illnesses. Our aim is to assess if and which classes of concomitant drugs have an impact on cytogenetic response in chronic phase (CP)-CML very elderly (age 〉 75 years) patients. Two hundred and twelve very elderly CP-CML patients, imatinib treated at 33 italian hematological institutions have been retrospectively evaluated. Median age at diagnosis was 78.5 years (range 75.0-93.0); 111 (52.4%) were male. Sixty-two (29.2%) were Sokal high risk. Sixty-seven (31.8%) were treated with reduced dose imatinib ( 〈 400 mg/day), and the remaining patients with imatinib 〉 400 mg/day. Concomitant drugs were 1-2 in 73 (34.4%) patients, 3-4 in 59 (27.8%), and 〉 5 in 64 (30.2%); 16 (7.6%) did not assume any concomitant drug. Drugs more frequently used were antiplatelets, assumed by 104 (49.1%) patients, followed by diuretics in 91 (42.9%) patients, proton pump inhibitors (PPIs) in 86 (40.6%), ACE inhibitors in 55 (25.9%), beta blockers in 44 (20.7%), angiotensin II receptors blockers (ARB) in 41 (19.3%), calcium channel blockers in 34 (16%), statins in 25 (11.8%), and alpha blockers in 11 (5.2%). Univariate logistic regression models were computed to assess the association between cytogenetic response after 6 or 12 months of imatinib treatment and number of concomitant drugs or selected drug classes. Statistical analyses were done using JMP 11.1 (SAS Institute Inc., Cary, NC, USA). Complete cytogenetic response (CCyR) was obtained in 124 (58.8%) patients, of whom 70 (33%) within 6 months. Consequently, we focused our study on the impact of number and types of drugs on CCyR rate, which represents the primary therapeutic endpoint in the elderly. Cytogenetic response distribution according to concomitant drugs is reported in table 1. We did not find any significant correlation between number of concomitant drugs, single classes of antihypertensive drugs, antiplatelets, PPIs or statins and CCyR rate at 6 or 12 months. Even though few pharmacokinetic interactions are reported between imatinib and some of medications we considered, this does not seem to have an impact on cytogenetic response rate in our cohort. Indeed, our results confirm the well-known safety and efficacy of imatinib also in very elderly CML patients. Table 1. Cytogenetic response according to concomitant drugs Drug classes Cytogenetic response CCyR 〈 6 months CCyR 7-12 months CCyR 〉 12 months No CCyR Antiplatelets (n=104) 38 (36.5%) 31 (29.8%) 11 (10.6%) 24 (23.1%) Diuretics (n=91) 32 (35.2%) 21 (23.1%) 13 (14.3%) 25 (27.4%) Proton pump inhibitors (n=86) 30 (34.9%) 22 (25.6%) 13 (15.1%) 21 (24.4%) ACE inhibitors (n=55) 19 (34.6%) 11 (20%) 12 (21.8%) 13 (23.6%) Beta blockers (n=44) 18 (40.9%) 11 (25%) 3 (6.8%) 12 (27.3%) Angiotensin II receptor blockers (n=41) 19 (46.3%) 11 (26.8%) 5 (12.3%) 6 (14.6%) Calcium channel blockers (n=34) 10 (29.4%) 7 (20.6%) 6 (17.7%) 11 (32.3%) Statins (n=25) 9 (36%) 7 (28%) 2 (8%) 7 (28%) Alpha blockers (n=11) 4 (36.4%) / 1 (9.1%) 6 (54.5%) Disclosures Castagnetti: Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; ARIAD: Consultancy, Honoraria. Abruzzese:BMS, Novartis, Pfizer, Ariad: Consultancy. Tiribelli:Bristol Myers Squibb: Consultancy, Speakers Bureau; Ariad Pharmaceuticals: Consultancy, Speakers Bureau; Novartis Farma: Consultancy, Speakers Bureau. Rosti:Novartis: Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau.