Abstract: Introduction Some retrospective studies in tyrosine kinase inhibitor (TKI)-resistant Philadephia-positive (Ph+) leukemia patients (pts) have suggested that deep sequencing (DS) may provide a more accurate picture of BCR-ABL1 kinase domain (KD) mutation status as compared to conventional sequencing (CS). However, the frequency and clinical relevance of low burden mutations remains to be explored prospectively in large series of unselected pts. In addition, the implementation of routine BCR-ABL1 DS in multiple molecular diagnostic laboratories has never been attempted. These open issues led us to design a multi-center, multi-laboratory prospective study ('NEXT-IN-CML') aimed to assess the feasibility, performance and informativity of DS for BCR-ABL1 KD mutation screening. Aims The first phase of the study was aimed to establish a network of 5 reference labs sharing a standardized DS workflow, a joint database for clinical and mutational data storage and a common pipeline of data analysis, interpretation and clinical reporting. The second phase of the study, involving 54 Italian Hematology Units, is aimed to assess the frequency and clinical significance of low burden mutations detectable by DS by prospective collection and analysis of samples from chronic myeloid leukemia (CML) pts who exhibit failure (F) or warning (W) responses and relapsed Ph+ acute lymphoblastic leukemia (ALL) pts. Methods A PCR and an amplicon DS protocol already set up and optimized for the Roche GS Junior in the framework of the IRON II international consortium was adopted. In the first phase, 5 batches of blinded cDNA samples were prepared and shipped to evaluate individual lab performances. The batches included archival samples with known BCR-ABL1 mutation status as assessed by CS and serial dilutions of BaF3 T315I+ cells in BaF3 unmutated cells, simulating mutation loads of 20% down to 1%. In the ongoing second phase prospectively, consecutively collected CML and Ph+ ALL samples are being analyzed in parallel by CS and DS. Clinical history and follow-up data are used for correlations. Results In the first phase of the study, 312/320 amplicons were successfully generated and sequenced. A median of 124,686 (range, 48,181-170,687) high quality reads were obtained across the 5 labs. Median number of forward and reverse reads was 1,757 (range 884-7,838), with no coverage dropouts for any amplicon or index. Comparison of observed vs expected mutations showed that 76/78 evaluable samples were accurately scored. In the remaining two, the analysis software failed to detect the 35bp insertion ('35INS') commonly detectable between exons 8 and 9. Quantitation of point mutation burden was highly reproducible across the entire range of frequencies, from 100% to 1%. The second phase of the study has started in Jan 2016. As of Jul 31st, a total of 106 consecutive pts (CML, n=96; Ph+ ALL, n=10) have been enrolled. The present analysis focuses on the first 75 CML pts (60 F and 15 W), for whom sequencing results are currently available (analysis of the entire population of patients enrolled up to Nov 2016 will be presented at the meeting). Clinically actionable mutations have been detected in 10/75 (14%) pts by CS and in 20/75 pts (27%) by DS. Notably, among the 10 pts positive for clinically actionable mutations by DS but not by CS, 3 had a low burden T315I (2 F [dasatinib, imatinib] and 1 W [dasatinib] ). In 5 additional pts negative for mutations by CS (3 F and 2 W), DS identified multiple low burden mutations with unknown IC50, suggesting that the cooperation of individually 'weak' mutants may be a new mechanism underlying reduced TKI efficacy. Longitudinal analysis and follow-up of pts are shaping the clinical significance of different types of low burden mutations and will be presented. Conclusions The 'NEXT-in-CML' study is demonstrating that DS of BCR-ABL1 can successfully be implemented in national lab networks and is an important step forward towards routine use of this technology. We have now adapted the protocol for both the Ion Torrent PGM and the Illumina Miseq platforms. For a minimum of 15 samples per sequencing run, DS costs are estimated to equal those of CS (cost per sample, reagents only: ≈100€ for PGM (314 chip) and Miseq (nano kit v2) vs ≈95€ for CS) with comparable turnaround times for delivery of results. Our study is also contributing useful data for the clinical interpretation of DS findings. Disclosures Soverini: Bristol-Myers Squibb: Consultancy; Ariad: Consultancy; Novartis: Consultancy. Castagnetti:ARIAD Pharmaceuticals: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Ciceri:MolMed SpA: Consultancy. Breccia:Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Honoraria; Celgene: Honoraria; Ariad: Honoraria; Pfizer: Honoraria. Di Raimondo:Janssen-Cilag: Honoraria. Bassan:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees. Cavo:Millennium: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Rosti:Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Ariad: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Baccarani:Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Saglio:Roche: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; ARIAD: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Martinelli:Ariad: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Novartis: Speakers Bureau; BMS: Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; MSD: Consultancy; Genentech: Consultancy.

Abstract: Median age of CML patients at diagnosis is reported to be around 66 years. Few data about the characteristics and outcome of patients younger than 40 years are available, and the clinical trials of dasatinib and nilotinib as first line treatment were not stratified by age. We retrospectively analyzed 251 young patients with CML in chronic phase from 12 different Italian Institutions, diagnosed between October 2001 and October 2016. Up to 2011 all patients were treated frontline with imatinib while from January 2011 onwards with imatinib or a second generation TKI (nilotinib or dasatinib), based on clinical judgment. At diagnosis median age was 32,6 years [interquartile range (IQR) 27,6- 36,9]; 143 (57%) were male. Splenomegaly was found in 129 out of 233 evaluable patients, in 29,2% of the cases spleen was palpable 〉 5 cm below the costal margin. The risk score was low in most of the cases (low risk Sokal 71%, low risk Eutos 91,3% vs high risk Sokal 9,8%, high risk Eutos 8,7%). Clinical features of the patients in treatment with different inhibitors are summarized in table 1. There were two main statistically significant differences in the group of patients treated with dasatinib: a higher proportion of high risk (30,8%) according to Eutos score and a lower median Hb level at diagnosis (8,5 gr/dL). These features probably reflected the trend of using dasatinib in patients with a more aggressive disease, as this drug was shown to be more potent since the first in vitro studies. Out of 251 patients 179 were treated with imatinib, 57 (22%) with nilotinib, 15 (5,9%) with dasatinib. Median follow up of the whole cohort was 76,5 months (IQR 41- 116); as expected, the follow up was longer in the imatinib group compared to the nilotinib and dasatinib groups (100 months vs 39,6 and 23,0 respectively). In the whole cohort, the cumulative incidence of Complete Cytogenetic Response (CCyR) and Major Molecular Response (MMolR) were 90,4% and 75,7% respectively; a deep molecular response (negative nested PCR, MR4.0, MR4,5) was achieved by 52.2% of patients, without differences among the 3 groups. Primary resistance occurred in 12,4% of patients, without differences among the 3 groups: secondary resistance occurred in 15.9% of patients, with a higher rate in the imatinib group (19,5%) as compared with nilotinib (7,0%) and dasatinib (6,7%) (p=0.047). Treatment discontinuation due to toxicity was observed in 6.0% of patients, without differences among the 3 groups. Blast transformation occurred in 7 out of 251 patients (2,8%), all in the imatinib group, after a median time from the diagnosis of 31 months (range 4-110). The 4-year cumulative Event-Free Survival (EFS) and Overall Survival (OS) were 72,4% (95%CI 66,7 - 78,5) and 98,1% (95%CI 96,4 - 99,8) respectively, without differences among the 3 groups. All deaths were related to blast transformation in imatinib group. In conclusion, as expected in a younger population, response to treatment and OS were excellent. However, the 4-year EFS was lower than expected, in spite of the presence of patients with predominantly low risk score. Furthermore, while the higher rate of secondary resistance in the imatinib group probably reflects the longer follow-up, it is worth of note that no statistically significant difference was observed between imatinib and 2nd generation TKI groups in terms of OS and EFS. Disclosures Breccia: Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Honoraria; Celgene: Honoraria; Ariad: Honoraria; Pfizer: Honoraria.

Abstract: Background Dasatinib has been recently licensed for first line treatment of patients with chronic myeloid leukemia (CML). However, very few data are available as to toxicity and efficacy of dasatinib in unselected elderly CML patients. Aim To address this issue, we revised a “real-life” cohort of 43 CML patients in chronic phase aged 〉 65 years treated with frontline dasatinib in 19 Italian Centers from 6/2012 to 6/2014 focusing on toxicity and efficacy data. Methods The main clinical features of the patients at diagnosis were as follows: M/F 20/23 (46.5%/53.5%), median age 75.2 years [interquartile range (IQR) 70.3 – 79.8), median Hb 12.5 g/dl (IQR 11.0 – 13.7), median WBC 57.7 x 109/l (IQR 29.5 – 100.0), median PLTS 466 x 109/l (IQR 249 – 758). According to Sokal risk classification, 3 patients (6.9%) were low risk, 26 (60.4%) intermediate risk, 10 (23.2%) high risk while 4 (9.5%) were not classificable. 20/43 patients (46.5%) had ≥ 2 comorbidities requiring concomitant therapies: according to ECOG scale, performance status at baseline was 0 – 1 in 36 patients (83.7%) and 2 in 7 patients (16.3%). Results Median interval from diagnosis to dasatinib start was 23 days (IQR 14 – 32). Dasatinib starting dose was 140 mg/day in 1 patient (2.3%), 100 mg/day in 33 patients (76.7%) and 〈 100 mg/day in 9 patients (21.0%), respectively. After a median period of treatment of 9.7 months (IQR 4.3 – 17.5) all patients were evaluable for toxicity; on the whole, grade 3 – 4 hematological and extra-hematological toxicities were reported in 4 (9.3%) and 6 (13.9%) patients, respectively. Overall, 7 patients (16.2%) permanently discontinued dasatinib due to toxicity (2 patients in the first 3-month period of treatment and 5 beyond that period). Pleural effusions of all WHO grades occurred in 7 patients (16.2%): in 2 of them the pleural effusion occurred during the first 3-month period of treatment. As to treatment efficacy, 6 patients were considered too early to be evaluated ( 〈 3 months of treatment) and 37 were evaluable for cumulative response; on the whole, 33/37 patients (89.1%) achieved complete cytogenetic response (CCyR) and 23/37 (62.1%) also a major molecular response (MMolR). Response to treatment at different time-points is shown on Table.3rd month6th month12th monthNot evaluable: Too early Not performed11651311219190Evaluable323024Discontinuation2 (6.2%)4 (13.3%)6 (25%)Less than CCyR6 (18,7%)2 (6.7%)0CCyR only17 (53.1%)5 (16.6%)4 (16.6%)MMolR7 (21.9%)19 (63.3%)14 (58.4%) Conclusions Present data shows that dasatinib could have a major role in the treatment of unselected patients aged 〉 65 years; indeed, dasatinib seems very effective and has a favourable safety profile also in elderly subjects with comorbidities. Disclosures Latagliata: Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Celgene: Consultancy; Shire: Consultancy. Gugliotta:Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Breccia:novartis: Consultancy; BMS: Consultancy; Celgene: Consultancy.

Abstract: Abstract 1229 In the “real world” of clinical practice, many very elderly CML patients have been treated with imatinib (IM), but there are few data on the results and the best initial dosage in such patients. To highlight peculiar aspects of toxicity and efficacy of IM in this subset which accounts for at least 10–15% of all CML cases, we retrospectively revised 156 CML patients in chronic phase treated with IM when aged 〉 75 years from 23 haematological Institutions in Italy; there were 85 males and 71 females, median age at IM start was 78.4 years (IR 76.1 – 81.4), Sokal Risk at diagnosis was low in 2 patients, intermediate in 90, high in 50 and not evaluable in 14. One or more concomitant diseases requiring specific treatments were present in 144/156 patients (92.3%), with 94 patients (60.2%) assuming 3 or more concomitant drugs. Thirty patients (19.2%) were in late chronic phase (≥ 12 months from diagnosis) and pretreated (25 with HU and 5 with IFN) before starting IM; on the whole, median time from diagnosis to IM was 1.2 months (IR 0.5 – 3.6). Starting dose of IM was 400 mg/day in 117 patients (75.0%) and 300 mg/day or less in 39 patients (25.0%); overall, 59 patients (37.8%) (52/117 at 400 mg starting dose and 7/39 at 3 300 mg starting dose) needed a dose reduction and 18 (11.5%) discontinued IM for toxicity (early toxicity in 13 and late toxicity in 5). Excluding the 13 patients who discontinued IM due to early toxicity, maximum tolerated daily dose during treatment was 400 mg in 63 patients, 300 mg in 51 patients and 〈 300 mg in 29 patients. According to CTC-AE, grade 3 – 4 hematological and extra-hematological toxicities were observed in 34 (21.7%) and 34 (21.7%) patients, respectively; 5 patients (3.2%) presented a pleural effusion during IM treatment. After a median treatment period of 29.4 months (IR 7.9 – 54.4), 8 patients (5.1%) are still too early ( 〈 6 months of treatment), 13 (8.3%) discontinued IM due to early toxicity, 3 (1.9%) were resistant and 1 (0.7%) died from unrelated cause early after IM initiation: the remaining 131 patients (84.6%) achieved a complete haematological response (CHR). Among these 131 patients in CHR, 11 refused any other karyotipic or molecular evaluation (1 lost CHR and shifted to hydroxyurea, 4 are still alive in CHR, 6 died in CHR from unrelated causes), 17 achieved CHR only and 103 (66.0% of all 156 patients) achieved a cytogenetic response (CyR), which was major in 11 patients and complete (CCyR) in 92 (58.9% of all 156 patients). In addition, among the 92 patients in CCyR, 62 (39.7% of all 156 patients) achieved a molecular response (major molecular response in 40 patients and complete molecular response with an undetectable BCR/ABL hybrid gene at qualitative nested PCR in 22 patients). After a median follow-up of 34.0 months (IR 12.9 – 60.0), 36 patients have died (5 from disease progression and 31 from unrelated causes), 4 patients were lost to follow-up and 116 are still alive: 2-year and 4-year overall survival were 90.2% (CI95% 84.8 – 95.6) and 76.8% (CI95% 68.6 – 85.0), respectively. In conclusion, results from this large unselected cohort of patients show that should be definitely considered unethical to avoid IM therapy to any elderly patient; no upper age limit should be given but also very elderly (and with concomitant severe diseases) patients should have this chance of cure. The role of a reduced starting dose of IM warrants further studies. Disclosures: No relevant conflicts of interest to declare.

Abstract: Introduction Treatment of chronic phase (CP) chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKIs) proved to be almost equally effective in young and elderly patients. Three TKIs, imatinib (IM), dasatinib (DAS) and nilotinib (NIL), are approved for frontline therapy in Italy. Choice of frontline TKI is based on a combined evaluation of patient's characteristics and expectations, with age usually playing a prominent role. However, to date, few data are available on patterns of TKI selection in very elderly patients. Aim To analyse the use of frontline TKI therapy in a large and unselected cohort of very elderly CP-CML patients Methods We retrospectively evaluated 332 patients aged ≥75 year diagnosed from 1/2012 to 12/2019 at 36 Hematology Centres participating at the "Campus CML" project. Results Clinical features at diagnosis for the whole cohort and according to frontline TKI are reported in Table 1. As to frontline TKI, 285 patients (85.8%) received IM and 47 (14.2%) a 2G-TKI (DAS n=28, 59.5%; NIL n=19, 40.5%). Of the 285 IM-treated patients, 192 (67.3%) started with standard dose (400 mg/day) and 93 (32.7%) with a reduced dose (300 mg/day n=64, 22.5%; & lt;300 mg/day n=29, 10.2%). Among the 47 patients starting a 2G-TKIs, 35 (74.4%) received standard dose and 12 (25.6%) a reduced dose (NIL & lt;600 mg/day n=3; DAS 80 mg/day n=4 and 50 mg/day n=5). There were no differences between patients treated with imatinib or 2G-TKI (Table 1); only a previous cerebrovascular event was reported in a significantly higher rate of IM-treated patients. It is however evident that the distinct toxicity profiles of NIL and DAS had an impact on TKI choice as, for example, no patient with diabetes or ischemic heart disease received NIL. Following widespread introduction of generic IM in Italy in early 2018, patients were divided in 2 groups: among 238 patients diagnosed from 2012 to 2017, 198 (83.1%) received IM and 40 (16.9%) a 2G-TKI, while patients diagnosed in 2018-2019 were treated with IM in 87/94 (92.5%) cases and with a 2G-TKI in 7 (7.5%) cases only (p=0.028). Conclusions IM remains the frontline drug of choice in very elderly CML patients, and this trend seems to increase after the introduction of the generic formulation. However, 2G-TKI are used in a small but sizeable group of patients, without a clear correlation with baseline CML features, thus probably reflecting a physician's evaluation of patient's fitness and/or expectation. Efficacy and safety of initial reduced TKIs doses in the setting of very elderly patients warrant further analyses. Figure 1 Figure 1. Disclosures Latagliata: Novartis: Honoraria; BMS Cellgene: Honoraria; Pfizer: Honoraria. Bonifacio: Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Bristol Myers Squibb: Honoraria. Elena: CELGENE: Other: funding for meeting participation; PFIZER: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; GILEAD: Membership on an entity's Board of Directors or advisory committees. Iurlo: Novartis: Speakers Bureau; Incyte: Speakers Bureau; Pfizer: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Stagno: Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; InCyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding. Abruzzese: Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Breccia: Bristol Myers Squibb/Celgene: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Pfizer: Honoraria; Novartis: Honoraria.

Abstract: Among 1967 Italian patients diagnosed between 2012 and 2019 with chronic‐phase chronic myeloid leukemia (CP‐CML), 1089 patients (55.4%) received imatinib and 878 patients (44.6%) received a second‐generation tyrosine kinase inhibitor: nilotinib or dasatinib. Factors associated with the predominant use of imatinib were age 〉 65 years, enlarged spleen, the presence of comorbidities (hypertension, diabetes, chronic obstructive pulmonary disease, previous neoplasms, ischemic heart disease, and stroke), and ≥3 concomitant medications at the time of CML diagnosis.

Abstract: To evaluate the role of bosutinib in elderly patients aged  〉 65 years with chronic myeloid leukemia (CML), a real‐life cohort of 101 chronic‐phase CML patients followed up in 23 Italian centers and treated with bosutinib in second or a subsequent line was retrospectively evaluated. Starting dose of bosutinib was 500 mg/day in 25 patients (24.8%), 400 mg/day in 7 patients (6.9%), 300 mg/day in 33 patients (32.7%), 200 mg/day in 34 patients (33.6%), and 100 mg/day in 2 patients (2.0%). Grade 3/4 hematological toxicity occurred in 7/101 patients (6.9%) and grade 3/4 extra‐hematological toxicity in 19/101 patients (18.8%). Permanent bosutinib discontinuation due to toxicity was needed in 12 patients (11.9%). Among the 96 patients evaluable for response, 74 (77.0%) achieved a complete cytogenetic response (CCyR), while 64 of these 74 patients in CCyR (66.6% of all 96 evaluable patients) also achieved a molecular response (MR) (major MR [MR 3.0] in 21 [21.8%] , deep MR [MR 4.0/4.5] in 43 [44.8%] ). The 3‐year event‐free survival and overall survival of the whole patients' cohort from bosutinib start were 60.9% (CI 95% 49.3–72.5) and 86.4% (CI 95% 77.2–95.6), respectively. Our real‐life data show that bosutinib is effective, with a favorable safety profile, also in elderly patients with important comorbidities and resistance and/or intolerance to previous tyrosine‐kinase inhibitor treatments. As a consequence, it could play a significant role in current clinical practice for frail patients.

Abstract: Here, we report real-world evidence on the safety and efficacy of nilotinib as a first-line treatment in elderly patients with chronic phase CML, treated in 18 Italian centers. Sixty patients aged  〉  65 years (median age 72 years (65–84)) were reported: 13 patients were older than 75 years. Comorbidities were recorded at baseline in 56/60 patients. At 3 months of treatment, all patients obtained complete hematological response (CHR), 43 (71.6%) an early molecular response (EMR), while 47 (78%) reached a complete cytogenetic response (CCyR). At last follow-up, 63.4% of patients still had a deep molecular response (MR4 or better), 21.6% reached MR3 as best response and 11.6% persisted without MR. Most patients (85%) started the treatment at the standard dose (300 mg BID), maintained at 3 months in 80% of patients and at 6 months in 89% of them. At the last median follow-up of 46.3 months, 15 patients discontinued definitively the treatment (8 due to side effects, 4 died for unrelated CML causes, 1 for failure, 2 were lost to follow-up). One patient entered in treatment-free remission. As to safety, 6 patients (10%) experienced cardiovascular events after a median time of 20.9 months from the start. Our data showed that nilotinib could be, as first-line treatment, effective and relatively safe even in elderly CML patients. In this setting, more data in the long term are needed about possible dose reduction to improve the tolerability, while maintaining the optimal molecular response.