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Here, we describe the immunoglobulin and T cell receptor (Ig/TCR) molecular rearrangements identified as a leukemic clone hallmark for minimal residual disease assessment in relation to TP53 mutational status in 171 Ph-negative Acute Lymphoblastic Leukemia (ALL) adult patients at diagnosis. The presence of a TP53 alterations, which represents a marker of poor prognosis, was strictly correlated with an immature DH/JH rearrangement of the immunoglobulin receptor (p < 0.0001). Furthermore, TP53-mutated patients were classified as pro-B ALL more frequently than their wild-type counterpart (46% vs. 25%, p = 0.05). Although the reasons for the co-presence of immature Ig rearrangements and TP53 mutation need to be clarified, this can suggest that the alteration in TP53 is acquired at an early stage of B-cell maturation or even at the level of pre-leukemic transformation.

Here, we describe the immunoglobulin and T cell receptor (Ig/TCR) molecular rearrangements identified as a leukemic clone hallmark for minimal residual disease assessment in relation to TP53 mutational status in 171 Ph-negative Acute Lymphoblastic Leukemia (ALL) adult patients at diagnosis. The presence of a TP53 alterations, which represents a marker of poor prognosis, was strictly correlated with an immature DH/JH rearrangement of the immunoglobulin receptor (p < 0.0001). Furthermore, TP53-mutated patients were classified as pro-B ALL more frequently than their wild-type counterpart (46% vs. 25%, p = 0.05). Although the reasons for the co-presence of immature Ig rearrangements and TP53 mutation need to be clarified, this can suggest that the alteration in TP53 is acquired at an early stage of B-cell maturation or even at the level of pre-leukemic transformation.

In adult acute lymphoblastic leukemia (ALL) the evaluation of clinical and biological conventional risk criteria at diagnosis is important but not sufficient to predict clinical outcome. The impact of TP53 mutations has been investigated in a limited number of studies and has still not been defined

SUMMARY While adult acute lymphoblastic leukemia (ALL) is curable in 40–50% of the patients, the individual prognosis is rather unpredictable due to associated biological and clinical risk factors. In both B- and T-precursor ALL, minimal residual disease (MRD) represents the most sensitive prognostic marker, useful to support critical treatment decisions, ranging from allogeneic stem cell transplantation in patients with inadequate MRD response to chemotherapy only in MRD responsive ones. This optimized risk-adapted strategy allows to spare transplant-associated morbidity and mortality in patients curable by chemotherapy. Further progress is expected from the integration of the MRD-based strategy with improved pediatric-type regimens and novel targeting agents for discrete ALL subsets. These changes are increasing the cure rate to above 50%.

Acute lymphoblastic leukemia (ALL) is curable in about 40-50% of adult patients, however this is subject to ample variations owing to several host- and disease-related prognostic characteristics. Currently, the study of minimal residual disease (MRD) following induction and early consolidation therapy stands out as the most sensitive individual prognostic marker to define the risk of relapse following the achievement of remission, and ultimately that of treatment failure or success. Because substantial therapeutic advancement is now being achieved using intensified pediatric-type regimens, MRD analysis is especially useful to orientate stem cell transplantation choices. These strategic innovations are progressively leading to greater than 50% cure rates.

The therapeutic role of mediastinal radiotherapy and stem cell transplantation (SCT) in lymphoblastic lymphoma (LL) remains controversial. In a risk-oriented design, we adopted a flexible treatment program in which (1) patients with persistent mediastinal abnormality, evaluated by post-induction computed chest tomography, received mediastinal irradiation; and (2) those with persistence of minimal residual disease (MRD), evaluated by MRD analysis of the bone marrow, underwent SCT. Twenty-eight out of 30 patients (T-lineage, n = 24; B-lineage, n = 6) achieved a complete response. Of 21 patients with mediastinal mass, 13 (62%) achieved a complete response after chemotherapy alone, while 6 (28.5%) required additional irradiation. Eleven patients were evaluated for MRD: 6 were negative and 5 positive. On the basis of MRD findings and clinical risk characteristics, 14 patients underwent SCT, 13 received maintenance chemotherapy, and 1 had local radiotherapy. Five patients relapsed. Among the 14 non-irradiated patients with T-LL, the mediastinal recurrence rate was only 7%. After a median follow-up of 3.9 years, 21 patients who responded were alive without recurrence (75%). The projected 5-year survival, disease-free survival, and relapse rate were 72%, 77%, and 18%, respectively. This program induced high remission and survival rates, indicating the feasibility and the benefits potentially associated with a selective, response-oriented policy of mediastinal irradiation and a concurrent MRD-based strategy to assign adult LL patients to SCT.

Clinical risk classification is inaccurate in predicting relapse in adult patients with acute lymphoblastic leukemia, sometimes resulting in patients receiving inappropriate chemotherapy or stem cell transplantation (SCT). We studied minimal residual disease (MRD) as a predictive factor for recurrence and as a decisional tool for postconsolidation maintenance (in MRDneg) or SCT (in MRDpos). MRD was tested at weeks 10, 16, and 22 using real-time quantitative polymerase chain reaction with 1 or more sensitive probes. Only patients with t(9;22) or t(4;11) were immediately eligible for allogeneic SCT. Of 280 registered patients (236 in remission), 34 underwent an early SCT, 60 suffered from relapse or severe toxicity, and 142 were evaluable for MRD at the end of consolidation. Of these, 58 were MRDneg, 54 MRDpos, and 30 were not assessable. Five-year overall survival/disease-free survival rates were 0.75/0.72 in the MRDneg group compared with 0.33/0.14 in MRDpos (P = .001), regardless of the clinical risk class. MRD was the most significant risk factor for relapse (hazard ratio, 5.22). MRD results at weeks 16 to 22 correlated strongly with the earlier time point (P = .001) using a level of 10−4 or higher to define persistent disease. MRD analysis during early postremission therapy improves risk definitions and bolsters risk-oriented strategies. ClinicalTrials.gov identifier: NCT00358072.

Background and Objectives The molecular analysis of minimal residual disease (MRD) may provide informaton on the risk of recurrence in patients with acute lymphoblastic leukemia (ALL). The aim of this study was to correlate the kinetics of MRD clearance after allogeneic transplantation with the clinical outcome of adults with ALL.Design and Methods MRD was evaluated by real-time quantitative polymerase chain reaction (RQ-PCR) using probes derived from fusion chimeric genes (BCR/ABL and MLL/AF4) (n=22) or rearrangements of the T-cell receptor or immunoglobulin genes (n =21). Forty-three adult patients with ALL were studied to correlate the kinetics of MRD clearance before and after allogeneic hematopoietic stem cell transplantation.Results At 36 months, the overall survival of patients who underwent transplantation in hematologic remission (n = 37) was 80% for those who were PCR-negative before transplantation (n = 12) compared to 49% for PCR-positive patients (n = 25)(p=0.17). For the same patients the cumulative incidence of relapse was 0% and 46%, respectively (p=0.027). Moreover, the relapse rate of patients who were PCR-negative at day +100 after transplantation was remarkably low (7%) compared to that among patients who were PCR-positive (80%, p=0.0006).Interpretation and Conclusions The kinetics of MRD clearance may help to identify patients at high risk of leukemia relapse after allogeneic stem cell transplantation. Patients not achieving an early molecular remission after transplantation require prompt and appropriate pre-emptive treatments such as infusions of donor lymphocytes or new experimental drugs.

Background and Aim of the Study For both childhood and adult Acute Lymphoblastic Leukemia (ALL) patients, clinical risk factors such as age, white cell count, response to steroids, time to complete remission, as well as biologic characteristics such as immunophenotype and cytogenetic at diagnosis are important but not sufficient in predicting clinical outcome. Aberrations of TP53 play a crucial role in the molecular pathogenesis of leukemias and lymphomas in which their presence is associated to disease progression and represents a strong predictor of poor clinical outcome. In childhood ALL, hereditary and acquired TP53 mutations are involved both in the pathogenesis and progression of the disease. In adult ALL, TP53 mutations are frequent in patients negative for recurrent fusion genes and correlate with poor response to induction therapy (Chiaretti S. et al, Haematologica 2013). The aim of this study was to evaluate the impact of TP53 alterations, analyzed by Next Generation Sequencing (NGS), on the outcome of a cohort of T (n= 57) and B (n= 114) precursor, Philadelphia (Ph) negative, adult ALL patients enrolled into the NILG-ALL 09/2000 clinical trial (ClinicalTrials.gov identifier: NCT00358072, Bassan R. et al, Blood 2009) in which molecular minimal residual disease was used to guide post-remissional therapy. Patients and Study design Among the 171 patients who were investigated for TP53 mutations, 16 proved also positive for t(4;11) and 3 for t(1;19). We analyzed DNA isolated from mononuclear cells obtained from bone marrow or peripheral blood samples containing at least 30% of blasts at diagnosis. The TP53 gene was sequenced using 454 ultra-deep sequencing (Roche Diagnostics) for alterations in exons 4 to 11, following the protocol developed in the IRON-II consortium. The sequencing data were analyzed by the Roche Diagnostics GS Run Browser and GS Amplicon Variant Analyzer software. The probabilities of survival were estimated using the Kaplan Meier method. The log-rank test was used to compare survival probabilities between subgroups of patients. Results and Discussion The data obtained by NGS allowed to identify 15 coding mutations detected in the DNA binding domain region (exons 5 to 8). These alterations were observed at diagnosis in 14 patients (8%), (11 B-precursor ALL and 3 T-ALL). In 12 cases these aberrations were single nucleotide changes, in 2 cases we found a duplication (one of 4 and the other of 8 nucleotides) and in one case there was an 11 base pair DNA insertion. Remarkably, all of these DNA alterations led to missense or frame-shift mutations that introduced a premature stop codon. Moreover, they were detected with a wide range of allele burden (from 5% to 97%) pointing out that TP53 mutations can be present at diagnosis in different proportions within the leukemic clones. All patients carrying a TP53 alteration reached complete remission after induction therapy but 13 out of 14 suffered an early relapse. Frequency of relapses was significantly higher in mutated than in wild-type cases (p=0.019). Relapse DNA samples were available in 3 patients and in all of them we detected the same TP53 mutation found at diagnosis, indicating the presence of a stable mutated clone. The univariate analysis enlightens a clear relationship between TP53 mutation with an increasing age (p= 0.0003) but no correlation with other clinical features such as gender, hemoglobin, white blood count, platelets, percentage of blasts and cytogenetics at diagnosis. Moreover, patients with mutated TP53 showed a Disease Free Survival (DFS) and Overall Survival (OS) dramatically shorter than wild-type patients. The 2 years DFS was 43% in the TP53 non-mutated subjects compared to 7% in the mutated (p=0.0007). Similarly, the 2 years OS was of 50% in wild-type patients and of 7% in mutated patients (p=0.0011) (Figure 1). Conclusions In adult ALL, response to induction chemotherapy is not different in patients with a wild-type or a TP53 mutated gene, but in these latter cases the leukemia relapse rate is dramatically higher. The frequency of these mutations observed at diagnosis and the poor clinical outcome indicate the need of their identification during the diagnostic work up of adult ALL to guide treatment strategies. The use of a highly sensitive deep sequencing approach is crucial to identify also minor leukemic clones carrying TP53 mutations that may lead to the rapid emergence of a treatment resistant disease. Disclosures Kohlmann: AstraZeneca: Employment.

Different molecular levels of post-induction minimal residual disease may predict hematopoietic stem cell transplantation outcome in adult Philadelphia-negative acute lymphoblastic leukemia

Abstract 2493 MRD is a powerful prognostic tool, increasingly adopted in adult ALL for a risk-oriented application of stem cell transplantation (SCT) in MRD-positive (MRDpos) patients. This policy gives the opportunity to assess the therapeutic value of allogeneic (or autologous) SCT in MRDpos patients, who are very unlikely to be cured by chemotherapy. In this study we reanalyze the long-term results of a prospective Northern Italy Leukemia Group trial (Bassan et al, Blood 2009;113:4153), aiming to determine which MRD levels were predictive of a better SCT outcome in MRDpospatients after induction/consolidation therapy. MRD was evaluated molecularly using one or two patient-specific probe(s) with sensitivity of at least 10−4. In remission patients, bone marrow MRD was assessed after chemotherapy courses no. 3 (week 10), 4 (week 16) and 6 (week 22). In the original risk model, MRDpos was defined by a level of 10−4 or greater at week 16 and/or any positivity at week 22. For this analysis, MRD results from all three time-points were pooled, and the highest value registered in individual patients was used to identify the MRD-negative group (always MRDneg) and three other subsets characterized by increasing levels of residual leukemia (less than 10−4 [MRDpos1], 10−4 and greater but less than 10−3 [MRDpos2], 10−3 and greater [MRDpos3]. Survival, disease-free survival (DFS), and relapse incidence were assessed and compared among these MRD groups, as well as outcome following SCT in MRDpossubsets, and this in accordance with protocol design i.e. in patients having SCT at end of consolidation phase after completion of the MRD study. Three-hundred and four patients with Ph- ALL were treated between 2000–2006 (median age 35 years, range 16–68; male gender 57%), of whom 258 (85%) entered complete remission. One or more sensitive probe(s)were available for 200 responsive patients (77.5%), of whom 141 completed consolidation and 59 did not because of elective early SCT in t(4;11)+ ALL (n=13), relapse (n=41) and toxicity (n=5). Of 141 evaluable patients, 136 completed the MRD study through weeks 10–22 (standard risk: 61 B-lineage and 14 T-lineage; high-risk: 41 B and 17 T; unspecified 3). Altogether, 64 patients were reclassified MRDneg (47%), 21 MRDpos1 (15.5%), 17 MRDpos2 (12.5%) and 34 MRDpos3 (25%). With a minimum observation time of 4 years and a maximum close to 12 years, estimated 6-year survival, DFS and relapse rates were 72.5%, 64% and 36% in MRDneg, 56%, 57% and 32% in MRDpos1, 48.5%, 46% and 50% in MRDpos2 and 23.5%, 15% and 76% in MRDpos3 cohorts, respectively (all P values In this study different MRD levels measured at weeks 10–22 were associated with a progressively worse outcome in the four patient subsets defined by the highest individual value at three study time-points. However, about one half of MRDpos1–2 patients could be salvaged by SCT, and even more with allogeneic rather than autologous SCT. Because of the very poor SCT results in MRDpos3 group, patients with MRD levels of 10−3 and greater should receive further therapy and not proceed to SCT until the MRD signal is below the 10−3 cutoff. Disclosures: No relevant conflicts of interest to declare.

Abstract 2573 Introduction In adult Ph- ALL two major risk groups are generally identified on account of patient age, presentation white blood cell (WBC) count, disease immunophenotype and genetics/cytogenetics, with 5-year overall and disease-free survival (OS, DFS) rates of approximately 50% in standard-risk (SR) and 30% in high-risk (HR) patients, respectively. Although the difference is significant, this classification reflects a static risk assessment and does not recognize increasingly important factors such as individual response dynamics (complete remission [CR] vs induction failure or early relapse; MRD course) and risk-oriented treatment decisions with or without stem-cell transplantation (SCT). Aim To evaluate dynamic risk factors in association with adherence to risk-oriented therapy as major determinants of outcome. Patients and Methods OS and DFS rates were reanalyzed according to MRD-related risk definitions and risk-oriented treatment steps in a prospective clinical trial (Bassan et al, Blood 2009;113:4153). Different risk and treatment subsets were identified according to (i) achievement of CR vs early failure due to induction death, early relapse or toxicity precluding the application of MRD/risk-oriented therapy according to trial design, and (ii) adherence to planned MRD/risk-oriented chemotherapy or SCT vs non-adherence unrelated to early failure. Outcome results were compared with those obtained using traditional SR and HR definitions. Results Three-hundred and four patients with Ph- ALL were treated (age range 16–68 years, median 35 years; male 57%), of whom 258 (85%) entered CR and 18 and 28 proved refractory or died early, respectively. Among CR patients, 78 did not complete early consolidation and MRD study (50 relapse, 9 toxicity and 19 very HR to early SCT), while 144 did it and were allocated to MRD-oriented therapy and 36 without a sensitive probe for MRD analysis were allocated according to clinical risk class. Six-year OS and DFS were 44% (n=138) and 43% (n=122) in SR vs 28% (n=166) and 28% (n=136) in HR, respectively (P=0.0009). Instead, OS and DFS results according to early treatment response, completion of MRD study for risk re-stratification and adherence to MRD/risk-oriented therapy identified several distinct prognostic categories, in which survival, largely unrelated to age and clinical risk class, ranged from 0% at 2.8 mos. (early deaths) to 73% at 6–10 years (MRD-negative), as detailed in the table and figure. Conclusion In this study, long-term survival rates were about 50% in SR patients (MRD unknown), 70% in MRD-negative ones receiving chemotherapy, and 40%–50% in all those proceeding to allogeneic SCT because very HR, HR MRD unknown or MRD-positive. Therefore, using a risk/MRD-oriented strategy, the adherence to protocol design concurs to identify the patient subsets with the highest probability of cure. Disclosures: No relevant conflicts of interest to declare.

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 WBC100, 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 ( 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 (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 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.

Clinical risk classifications fail to predict relapse (REL) in about 25% and 50% of high- and standard-risk (HR, SR) ALL patients (pts.), respectively, with potential under-/over-exposure to chemotherapy or allogeneic stem cell transplant (SCT, with intrinsic mortality ≥20%). Between 2000–5, we studied MRD as major predictive factor for REL and key decisional tool for SCT or less aggressive therapy in individual pts. with SR/HR ALL. Induction/consolidation consisted of Ida/V/P/Asp/CY (blocks 1–3,5,6,8), HD-MTX/Ara-C (4,7), CNS phase and imatinib (Ph+). Risk classes were SR (pre-B, WBC30 [B]/100 [T]), and very HR (VHR) i.e. Ph/t(4;11)+. All cases were screened for fusion genes or IgH/TCRβγδ/Kde rearrangements (23/22 PCR amplifications for B/T subsets, respectively). Marrow cells obtained before blocks 4,6,8 (week 10,16,22 i.e. timepoints [TP]1-3) were analyzed by RQ-PCR using 1 or more pt.-specific probes. MRD negativity (Mneg) was defined by negative/low-positive (30; P