Abstract: Since the landmark study of Omura et al. (Blood 1980;55:199), validating cranial irradiation as an adjunct to intrathecal (IT) methotrexate, no other randomized trial of CNS prophylaxis was performed in adult ALL. Although the risk of CNS relapse is now only 1-4%, irradiation contributes to cumulative CNS toxicity together with high-dose methotrexate/cytarabine (HD-M/A), or is logistically difficult, so that developing an effective radiation-free CNS prophylaxis remains an important clinical task. IT DepoCyte® (ITD) might be advantageous, the slow release of liposome-associated cytarabine allowing therapeutic concentrations in the cerebrospinal fluid for 14+ days. An open trial reported prohibitive CNS toxicity from ITD in 6/31 patients (Jabbour et al. Blood 2007;109:3214), but ITD to ITD and HD-M/A to ITD intervals were short (14 and 10 days, respectively) and no patient suffered from CNS relapse. Methods In a phase II randomized trial (ClinicalTrials.gov NCT-00795756) we evaluated toxicity and feasibility (as primary study endpoint) of ITD 50 mg in comparison with IT triple therapy (ITT: methotrexate 12,5 mg, cytarabine 50 mg, prednisone 40 mg). Stratification was by cell lineage and risk class. ITT was given on d1 of courses 1,2,4,6,8; d15 of courses 1,2,8; and d1 of maintenance cycles 2-5 (12x). ITD was given on d1 of courses 1,2,4,6,8; d15 of courses 1,8 (T-ALL only); and d1 of maintenance cycle 2 (6-8x). The shortest ITD to ITD interval was 14 days in T-ALL (courses 1-2 [3x] and 8 [2x] ), otherwise it was 21 days between ITD and any prior/subsequent ITD and HD course. ALL therapy consisted of eight induction-consolidation courses followed by risk/minimal residual disease-oriented maintenance or stem cell transplantation (SCT). In HD courses 3,7 (M/A) and 5 (M/Asparaginase) M dosage was 2.5 g/m2 (Ph- B-ALL) and 5 g/m2 (T-ALL) up to 55 years, and A 2 g/m2. Imatinib was used with de-intensified chemotherapy in Ph+ ALL; selected high-risk subsets received early SCT. Results Between 2007-12 201 total patients were enrolled and 141 randomized to ITT (n=73) or ITD (n=68). Median age was 42 years (range 18-68) and risk subsets (ITT/ITD) were SR-B 27.4%/29.4%; HR-B Ph- 26%/25%, Ph+ 23.3%/22.1%, SR-T 5.5%/5.9%, HR-T 17.8%/17.7%. Complete remission was 89% (n=65)/89.7% (n=61). Rates of actual v planned IT injections during induction-consolidation cycles 1-8, after removal of study losses (resistance, early death, SCT, toxicity and relapse), were ITT 374/415 (90.1%) v ITD 219/245 (89.3%) (P=0.76). Although toxicity/medical reasons caused 5 ITD patients to discontinue permanently the study v none in ITT arm (P=0.02), toxicity-driven omissions of IT therapy were marginally increased in ITD arm (29/415 [6.9%] v 24/245 [9.8%] ; P=0.20). Neurologic toxicity occurred in 20 (27.4%) ITT v 36 (53%) ITD patients, respectively (P=0.002). According to NCI CTC grading (G), neurotoxicity episodes were GI 7 v 10 (P=0.36), GII 13 v 32 (P=0.003), GIII 4 v 12 (P=0.04), GIV 1 v 5 (P=0.12). GIII-IV neurotoxicity developed in 5/73 (6.8%) ITT patients v 10/52 (19.2%) and 5/16 (31.2%) B- and T-ALL ITD patients, respectively (P= 0.01), correlating in T-ALL with the second/third q14d ITD at courses 1,2,8 (4/5 patients, 5/6 episodes). Apart from reversible headache/radicular pain, the most serious toxicity occurred in 3 (4.1%) ITT patients (seizures 1; leukoencephalopathy 1; loss of consciousness 1) v 5 (7.3%) ITD patients (loss of consciousness 4, 1 with seizures; cerebral oedema/pseudotumor cerebri 1) (P=0.48). Four-year overall and disease-free survival were 54% and 52.2% v 58.9% and 47.7% in ITT and ITD arms, respectively, and relapse rate was 32.3% v 24.6% (all P=NS). In ITT arm there were 2 (3%) CNS and 2 (3%) combined CNS/marrow relapses. In ITD arm only one poorly compliant subject not given any HD course had an isolated CNS relapse (1.6%); no other patient had a CNS recurrence. Conclusion A radiation-free CNS prophylaxis with six spaced ITD in conjunction with HD-M/A may be feasible and at least as effective as other regimens. Excluding reversible headache/radiculitis, serious CNS toxicity was not significantly increased compared with ITT regimen, although some patients were forced to discontinue IT prophylaxis. The occasionally severe CNS toxicity prompts the investigation of a lower ITD dosage (25 mg), also to limit GI-II side effects, and the tighter schedule used in T-ALL should be abandoned because too toxic. Disclosures: Bassan: Mundipharma Oncology; Sigma-Tau; Amgen: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Off Label Use: Liposome-encapsulated cytarabine (DepoCyte®) used in a prospective phase II randomized trial of CNS prophylaxis in ALL. Masciulli:Novartis: Research Funding; Ospedali Riuniti di Bergamo: Research Funding; AIFA (Italian Regulatory Agency): Research Funding; AMGEN S.p.A.: Research Funding; Genzyme Olanda: Research Funding; Gruppo Italiano Trapianti di Midollo Osseo (GITMO): Research Funding; Pierre Fabre Italia S.p.A.: Research Funding; Università Cattolica del Sacro Cuore, Roma: Research Funding; Università degli Studi di Firenze: Research Funding; Sigma-Tau: Research Funding; Myeloproliferative disorder Research Consortium: Research Funding; Celgene: Research Funding; Associazione Italiana Linfomi (AIL): Research Funding; Fondazione Italiana Linfomi (FIL): Research Funding; LaRoche: Research Funding. Gallamini:Millenium: Consultancy. Marfisi:Novartis: Research Funding; Ospedali Riuniti di Bergamo: Research Funding; AIFA (Italian Regulatory Agency: Research Funding; AMGEN S.p.A.: Research Funding; Genzyme Olanda: Research Funding; Gruppo Italiano Trapianti di Midollo (GITMO): Research Funding; Pierre Fabre Italia S.p.A.: Research Funding; Università Cattolica del Sacro Cuore-Roma: Research Funding; Università degli Studi di Firenze: Research Funding; Sigma-Tau: Research Funding; Myeloproliferative disorder Research Consortium: Research Funding; Celgene: Research Funding; Associazione Italiana Linfomi (AIL): Research Funding; Fondazione Italiana Linfomi (FIL): Research Funding; LaRoche: Research Funding. Marchioli:Associazione Italiana Linfomi (AIL): Research Funding; Celgene: Research Funding; Myeloproliferative disorder Research Consortium: Research Funding; Sigma-Tau: Research Funding; Università Cattolica del Sacro Cuore, Roma: Research Funding; Pierre Fabre Italia S.p.A.: Research Funding; Gruppo Italiano Trapianti di Midollo (GITMO): Research Funding; Genzyme Olanda: Research Funding; AMGEN S.p.A.: Research Funding; AIFA (Italian Regulatory Agency): Research Funding; Ospedali Riuniti di Bergamo: Research Funding; Novartis: Research Funding; Fondazione Italiana Linfomi (FIL): Research Funding; LaRoche: Research Funding; Università degli Studi di Firenze: Research Funding. Rambaldi:Italfarmaco: Honoraria; Sanofi: Honoraria; Novartis: Honoraria.

Abstract: Abstract 2131 Background. Some studies have shown how the use of pediatric-type therapy (PDT) and minimal residual disease (MRD)-oriented programs could improve outcome of adult ALL. Study Design. We included PDT elements in a pilot trial started January, 2008. Protocol 10/07 consisted of standard induction and late reinduction courses plus 3 PDT blocks (modified after BFM therapy) alternating with 3 lineage-targeted Methotrexate (LTM) blocks (B-precursor: 2.5 g/m2; T-precursor: 5 g/m2; Ph+ or age 〉 55 years: 1.5 g/m2). LTM targeted a Methotrexate plasma concentration of ∼35 and ∼65 micromol/L in B- and T-ALL, respectively, in line with a therapeutic concept developed at St. Jude's Hospital (Memphis, TN, USA) in childhood ALL. The program was integrated by (a) a randomised, radiation-free central nervous system (CNS) prophylaxis study comparing intrathecal Methotrexate, Ara-C, and Prednisone (×12) vs. liposomal Ara-C (DepoCyte 50 mg, ×6 [B-ALL]-8 [T-ALL] ); (b) the molecular evaluation of MRD at pre-fixed treatment weeks (w), to optimise risk stratification and indications for allogeneic stem cell transplantation (allo-SCT); and (c) by concurrent imatinib in patients with Ph+ ALL. The whole chemotherapy plus MRD study sequence was as follows: prephase (Prednisone, Cyclophosphamide) → induction (Idarubicin, Vincristine, Asparaginase, Dexamethasone) + w4 MRD → PDT1 (Cyclophosphamide, Vincristine, Idarubicin, Dexamethasone, Ara-C, 6-mercaptopurine) → LTM1 (plus high-dose Ara-C) + w10 MRD → PDT2 → LTM2 (plus Asparaginase) + w16 MRD → PDT3 → LTM3 (plus HD Ara-C) + w22 MRD → reinduction (Idarubicin, Vincristine, Cyclophosphamide, Dexamethasone). CNS prophylaxis was administered only during PDT blocks, with a minimum interval 〉 15 days from/to LTM cycles. Risk classes were standard (SR: pre-B and WBC 〈 30; cortical T and WBC 〈 100; CR at cycle 1) and high (HR: other subsets). Allo-SCT was prescribed as soon as possible to all patients with Ph/t(4;11)+ ALL or other highly adverse cytogenetics; with WBC 〉 100, or CD1a-negative early or mature T phenotype; and to SR/HR patients with MRD 〉 10-4 after LTM1 (w10) or detectable at any level after LTM3 (w22). Autologous SCT followed by maintenance was a suitable alternative when allo-SCT was not feasible. All patients not eligible to frontline allo-SCT and with low positive ( 〈 10-4) or negative MRD results were submitted to standard maintenance. Results. Seventy-five of 81 evaluable patients (median age 40 years [range 18–65], 54% male, 23% T-ALL, 60% HR, 20% Ph+) achieved CR (92.5%); 55 of them (73.5%) were alive in CR1 at time of interim analysis (April, 2010). Sixteen patients relapsed (21.5%) and four died in CR of therapy-related complications (one after allo-SCT and 3 aged 〉 55 years after a PDT cycle). With a maximum follow-up slightly 〉 2 years (27.5 mos.), projected overall survival (OS) at 1.5 years is 73% (95% CI 57%-83%), and disease-free survival (DFS) 66% (95% CI 52%-77%). The best results were observed in patients aged 55 years and less (n=65, OS 79%) and those with T-ALL (n=20, OS 86%). These findings correlated well with a favourable early MRD response in Ph-negative subsets: 49% of evaluable cases achieved a major MRD response ( 〈 10-4) at end of induction cycle (w4: MRD negative 6/13 T [46%] vs. 7/24 B [29%] ; 〈 10-4 2 T and 3 B; overall 61.5% T and 42% B), as did 64% of the patients after LTM1 (w10: MRD negative 11/15 T [73%] and 16/27 B [59%] ; 〈 10-4 2 T and 1 B; overall 87% T and 63% B). MRD results were predictive of CR durability. Pooled MRD data from all time-points (w4-22) indicated a probability of CR of 92% in 18 patients with all results 〈 10-4 vs. 60% in 19 patients with at least one MRD value 〉 10-4 (P=0.039). The flexible risk- and MRD-adapted SCT policy resulted in high early transplantability rate in patients with this indication (70% in T-ALL). Finally, the randomised CNS prophylaxis trial preliminarily confirmed the feasibility of intrathecal DepoCyte as planned (total randomised patients = 57). Conclusions. This regimen was highly active, yielding a 〉 90% CR rate in unselected adults aged up to 65 years, with a major early MRD response of 63% in Ph-negative B-ALL and 87% in T-ALL. The toxicity observed after PDT blocks in a first group of patients aged 〉 55 years required a reduction of PDT dose intensity in this age group. LTM therapy proved feasible, up to 5 g/m2 in T-ALL, and remarkable early OS/DFS rates were obtained in T-ALL and in unselected patients aged 〈 55 years. Disclosures: Bassan: Mundipharma: Consultancy, Research Funding. Off Label Use: Study is devoted to assess feasibility/toxicity/value of intrathecal liposome-encapsulated cytarabine (DepoCyte) vs standard intrathecal therapy as prophylaxis of CNS recurrence in adult ALL.

Abstract: Introduction. The application of Pediatric-Type Therapy (PTT) programs to adults with ALL can improve outcome significantly despite higher age-related toxicity. Recent series reported survival rates ≥ 50%, but only few combined PTT with Minimal Residual Disease (MRD) study for risk-oriented Hematopoietic Cell Transplantation (HCT) and/or explored the value of specific PTT element such as higher dose, lineage-targeted MTX up to 5 g/m2. Methods. To improve over prior data, NILG protocol 10/07 (Clinical.Trials.gov NCT-00795756) for unselected adult patients aged 18-65 years combined PTT together with MRD study for risk/MRD-based HCT. The 8-course program consisted of a 5-drug complete remission (CR) induction (cycle no. 1; imatinib added if Ph+) followed by 3 modified BFM blocks (no. 2, 4 and 6), 3 lineage-targeted MTX blocks (no. 3, 5 and 7; MTX 5 g/m2 for T-ALL and 2.5 g/m2 for B-ALL [1.5 g/m2 if age 〉 55 years or Ph+]; no. 3 and 7 with high-dose Ara-C 2 g/m2 x4, no. 5 with L-Asp 10,000 IU/m2 x2) and reinduction (no. 8). CNS prophylaxis was with triple intrathecals or liposomal cytarabine (Haematologica 2015;100:786). MRD was studied molecularly with sensitive probe(s) (sensitivity 10-4 or greater) on marrow samples obtained at end of induction (week 4, w4) and after cycles 3 (w10), 5 (w16), 7 (w22) i.e. after 1st, 2nd and 3rd lineage-targeted MTX block. Patients were risk-stratified at diagnosis and after MRD analysis for the purpose of allocation to HCT or conventional maintenance. The HCT allocation cohort consisted of predefined very high-risk patients (vHR: WBC 〉 100, highly adverse cytogenetics, pre-T/mature T-ALL) regardless of MRD, of HR patients without MRD study (HR: late CR; B-ALL with WBC 〉 30 or pro-B phenotype), and of HR or standard-risk (SR) patients with MRD ≥ 10-4 at w10/16 or positive at w22. Conversely, the maintenance allocation cohort consisted of SR and HR patients with MRD 〈 10-4 at w10/16 and negative at w22 and of SR patients without MRD study. A family related/unrelated donor search was activated at diagnosis in order to proceed to HCT soon after cycle no. 3 when needed. Results. 205 patients were enrolled, with a median age of 41 years (range 17-67 years, 11% 〉 60 years). 55% were male, 42 had Ph+ ALL, 119 Ph- B-ALL and 44 T-ALL. Of 163 patients with Ph- ALL, 45% were SR, 13% HR and 42% vHR. CR rate was 98% in Ph+ ALL and T-ALL, and 83% in Ph- B-ALL (88% vs 58% in patients ≤ vs 〉 60 years, P .0013). The MRD study was successful in 109/142 CR patients with Ph- ALL (77%), contributing to the final risk classification in 63 patients, of whom 41 were MRD responsive (65%) and 22 MRD resistant (35%). Altogether, 55 CR patients constituted the maintenance allocation group (39%) and 87 the HCT allocation group (61%), which included mainly vHR patients (n=61, 43%) selected for HCT independently of MRD study results. According to intention-to-treat, median OS is not reached (53% at 5 years, figure) and median DFS is 4.8 years (48% at 5 years). In Ph- ALL, 5-year OS/DFS are 74%/61% in T-ALL (medians not reached) and 48% each in B-ALL (medians 3.9 and 4.7 years). Median OS is not reached in both HCT and maintenance allocation groups (58% and 73% at 5 years, respectively, P .078), with a median DFS of 4.7 years (48% at 5 years) versus not reached (59% at 5 years) (P .19). Treatment adherence was good with some exceptions in maintenance allocation group (6 HCT, 11%) and a transplant realization of 68% (53 allogeneic; 6 autologous) in HCT allocation group. With HCT, 5-year incidence of nonrelapse mortality was 17%. The MRD analysis proved that DFS of patients achieving an MRD response 〈 10-4 at w4 (n=46/90, 51%) or w10 (n=76/107, 71%) was significantly improved compared to those with MRD ≥ 10-4, with median not reached and 5-year rate 67% versus 4.5 years and 41% (w4 MRD; P .041), and 7.2 years and 64% versus 1 year and 23% (w10 MRD; P .0001). Conclusion. The current PTT and MRD-based risk-oriented strategy was applicable to adults with ALL in a wide age range, with some limitations in patients 〉 60 years. 5-year OS and DFS of 55% and 52% respectively in Ph- patients aged up to 65 years represent an improvement over prior NILG study (5-year OS and DFS of 36% and 35% respectively). MRD was essential in orientating the HCT choice in SR and HR patients and retained a major prognostic role in all patients. Optimizing the early MRD response with new immunotherapeutics and clarifying the role of HCT in MRD responsive vHR patients are some relevant topics of future research. Figure Figure. Disclosures Ciceri: MolMed SpA: Consultancy. Vitolo:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; Gilead: Honoraria; Celgene: Honoraria; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Gallamini:Millenium Takeda: Membership on an entity's Board of Directors or advisory committees.

Abstract: Genetic and Clinical Background: The clinical outcome of Core Binding Factor Leukemia (CBFL) seems influenced by the mutational status of KIT. In fact, several retrospective studies, in addition to our own, as well as a systematic review, indicate that KIT mutations have a negative prognostic impact in AML with t(8;21) or, to a lesser extent, with inv(16)/t(16;16). In addition, gene expression studies found KIT to be highly expressed in CBFL regardless of its mutational status. Furthermore, recent studies have identified novel recurrent somatic mutations co-occurring with KITmut. In-vitro studies revealed that Midostaurin (Mido) is effective in inhibiting both wild type (WT) and a range of KIT mutants. In addition, it is proven to be effective in KIT-positive malignancies such as Aggressive Systemic Mastocytosis (ASM), Mast Cell Leukemia (MCL), and SM with Associated Hematological Neoplasm (SM-AHN). With this background, we designed a Phase II trial to evaluate the safety and efficacy of Mido in association with Intensive Chemotherapy (IC), in CBFL regardless of KIT mutational status. Methods: The inclusion criteria were the following: age 18 to 60 years, diagnosis of de-novo CBFL, adequate organ function, signed informed consent. The exclusion criteria were: central nervous system involvement, uncontrolled infections, other active malignancies, a Qtc value greater than 470 ms (according to Bazett formula) at the electrocardiogram, significant uncontrolled or active cardiovascular diseases. Patients received standard induction therapy with an anthracycline containing regimen ("7+3"-like) + Mido, three cycles of post-remission consolidation chemotherapy with high-dose cytarabine + Mido, and 12 months of Mido as Maintenance. The Mido dosage was: 50 mg orally twice a day, on days 8-21, in association with IC, and 50 mg orally twice a day as single agent maintenance. In order to attain a reduction in 2 years Relapse Incidence (RI), from the historical value of 48% to 28% (Primary Objective of the Study), we plan to enrol 39 patients (power 82%, alpha error 4,6%). At diagnosis all patients were studied by a comprehensive NGS panel targeting 40 DNA genes and 29 RNA fusion driver genes. MRD status was assessed by qPCR and high-resolution multicolor flow cytometry at established check-points during consolidation and maintenance therapy. Results: 17 patients were enrolled between December 2018 to April 2020 (table1). Overall, the CR rate was 94.2%. At a median follow-up of 9 months (range 3-19 months), we recorded a RI of 12.5%, an OS of 93.7%, and a DFS of 81.2%. 16 patients continue on study and 14 patients are in 1st CR, MRD-negative by flow cytometry and qPCR. Six patients (35.2 %) experienced 12 Treatment Emergent Adverse Event (TEAE), 10 out of whom were infections, with grade 3-4 neutropenia (Table 2). We only recorded one death from SARS-Cov2 infection (Interstitial Pneumonia) in a patient in MRD-negative complete remission. There were no treatment-related deaths. Conclusion: In patients with CBFL, the regimen consisting of intensive chemotherapy and consolidation chemotherapy in association with Mido, followed by Mido maintenance, had an acceptable safety profile and excellent response rates with a significant proportion of patients in MRD-negative complete remission. Trial is continuing to accrue (EudraCT Number 2017-002094-18; ClinicalTrials ID: NCT 03686345). This work was supported by a grant from Fondazione Regionale per la Ricerca Biomedica (FRRB 2015). Disclosures Krampera: Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Todisco:Jannsen, Abbvie, Jazz: Membership on an entity's Board of Directors or advisory committees. Veronese:Novartis: Other: Travel Expenses; Bayer: Honoraria; AstraZeneca: Other: Travel Expenses; Janssen Cilag: Honoraria. OffLabel Disclosure: Midostaurin for treatment of Core Binding Factor Leukemia. The drug has been used as KIT inhibitor.