Abstract: Splenic marginal zone B-cell lymphoma (SMZL) is a heterogeneous clinico-biological entity. The clinical course is variable, multiple genes are mutated with no unifying mechanism, and essential regulatory pathways and surrounding microenvironments are diverse. We sought to clarify the heterogeneity of SMZL by resolving different subgroups and their underlying genomic abnormalities, pathway signatures, and microenvironment compositions to uncover biomarkers and therapeutic vulnerabilities. We studied 303 SMZL spleen samples collected through the IELSG46 multicenter international study (NCT02945319) by using a multiplatform approach. We carried out genetic and phenotypic analyses, defined self-organized signatures, validated the findings in independent primary tumor metadata and determined correlations with outcome data. We identified 2 prominent genetic clusters in SMZL, termed NNK (58% of cases, harboring NF-κB, NOTCH, and KLF2 modules) and DMT (32% of cases, with DNA-damage response, MAPK, and TLR modules). Genetic aberrations in multiple genes as well as cytogenetic and immunogenetic features distinguished NNK- from DMT-SMZLs. These genetic clusters not only have distinct underpinning biology, as judged by differences in gene-expression signatures, but also different outcomes, with inferior survival in NNK-SMZLs. Digital cytometry and in situ profiling segregated 2 basic types of SMZL immune microenvironments termed immune-suppressive SMZL (50% of cases, associated with inflammatory cells and immune checkpoint activation) and immune-silent SMZL (50% of cases, associated with an immune-excluded phenotype) with distinct mutational and clinical connotations. In summary, we propose a nosology of SMZL that can implement its classification and also aid in the development of rationally targeted treatments.

Abstract: Introduction. The majority of SMZLs display an indolent course, however the disease is still incurable and a significant proportion of patients (~25-30%) experience poor outcomes surviving 〈 5 years. Molecular alterations of SMZL are promising biomarkers, which might improve risk stratification of patients. The main objective of the study is to test the impact of molecular aspects on disease-specific survival prognostication in newly diagnosed SMZL. Methods. IELSG46 is a multicenter, international, retrospective, observational study in which already existing and coded health-related personal and biological material is used. The study included adults, who received a diagnosis of SMZL on spleen histology with a follow up 〉 5 years, and for whom tumor material collected before initiation of medical therapy was available. Mutation analysis was performed by CAPP-seq targeted deep next generation sequencing of tumor genomic DNA. A stringent bioinformatic pipeline was applied to suppress the background noise allowing to call variants with a sensitivity of 5x10-2 in FFPE derived DNA. Copy number variations (CNVs) were identified by using the sequencing reads-based GATK4-CNV algorithm. IGHV rearrangements were obtained by using LymphoTrack® IGH FR1 Assay Panel kit. Molecular clusters were identified by an iterative algorithm that maximizes genetic distinctiveness of subgroups by reassigning patients between clusters that are created a priori based on the co-occurrence of genetic lesions. Relative survival, defined as the ratio between actuarial survival observed in the SMZL cohort and expected survival of the general population matched to patients by geographical origin, sex, age and calendar year of diagnosis, was calculated using the Ederer II method. Results. The analysis included 303 patients with a SMZL diagnosis confirmed on spleen histology. The sample size allowed to identify 30% differences in survival for molecular subgroups comprising at least 5% of cases with a statistical power between 80-100%. Median follow-up was 9.2 years. At 10 years, 85% of patients were alive, consistent with the known indolent behavior of this lymphoma. Genes recurrently affected by non-synonymous somatic mutations in 〉 10% of SMZL included KLF2 (24%), NOTCH2 (19%), KMT2D (15%), TNFAIP3 (13%), EP300 and TP53 (10%). Deletion 7q was documented in 25% of cases and IGHV1-2*04 usage in 32%. By cluster analysis, three major molecular subgroups were identified, each of them characterized by a NOTCH pathway mutated gene (Fig. 1A). The first cluster was defined by NOTCH2 and/or KLF2 mutations and was enriched in TNFAIP3 mutations and IGHV1-2*04 gene usage (Fig. 1A). The second cluster was defined by SPEN mutations, and was enriched in KMT2D and other epigenetic gene mutations (Fig. 1A). The third cluster was enriched in NOTCH1 mutations (Fig. 1A). By relative survival analysis, the NOTCH2/KLF2 cluster showed a lower survival compared to the matched general population, indicating a significant impact of the disease on patients' expected survival (Fig. 1B). Conclusions. The large sample size and inclusion of SMZL confirmed by spleen histopathology review allowed for precise estimation of the prevalence of KLF2 and NOTCH2 mutations in this lymphoma. Three molecular clusters were identified in SMZL, each of them containing a NOTCH pathway gene, supporting the relevance of NOTCH signaling in the pathogenesis of SMZL. Patients belonging to the NOTCH2/KLF2 cluster had a lower relative survival compared to the matched general population. Disclosures Traverse-Glehen: Astra Zeneca: Other: Travel; Takeda: Research Funding. Gomes da Silva:Roche: Other: Institution's payment for consultancy, Travelling support; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: lecture fees; Celgene: Other: Travelling support; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: lecture fees, Institution's payment for consultancy, Travelling support; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: lecture fees; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: lecture fees, Research Funding. Ladetto:Celgene: Honoraria; Jannsen: Honoraria; Acerta: Honoraria; Abbvie: Honoraria; Sandoz: Honoraria; Roche: Honoraria. Rambaldi:Pfizer: Consultancy; Novartis: Consultancy; Omeros: Consultancy; Italfarmaco: Consultancy; Amgen Inc.: Consultancy; Roche: Consultancy; Celgene: Consultancy. Vitolo:Takeda: Speakers Bureau; Sandoz: Speakers Bureau; Gilead: Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Zinzani:MSD: Honoraria, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; SERVIER: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; PFIZER: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees; TG Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees; PFIZER: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Speakers Bureau. Gaidano:Roche: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Morphosys: Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Salles:Servier: Honoraria; Abbvie: Honoraria; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; Amgen: Honoraria; BMS: Honoraria, Other: Advisory Board; Celgene: Honoraria, Other: Advisory Board, Research Funding; Acerta: Honoraria; Janssen: Honoraria, Other: Advisory Board; Merck: Honoraria; Pfizer: Honoraria; Morphosys: Honoraria; Gilead: Honoraria, Other: Advisory Board; Epizyme: Honoraria; Servier: Honoraria, Other: Advisory Board; Takeda: Honoraria. Zucca:Celltrion: Consultancy; AstraZeneca: Consultancy.

Abstract: Introduction .Treatment of multiple myeloma (MM) patients (pts) has radically changed over the last years following the introduction of next generation proteasome inhibitors (PI) and immunomodulatory derivatives (IMiDs). Despite the improvement of pts' outcome due to these drugs, MM remainsan incurable disease given its propensity for clonal heterogeneity and its complex interaction with the surrounding bone marrow microenvironment. Almost all pts eventually relapse despite their responses to PI, IMiDs or both. Recently, one further therapeutic option for MM patients is represented bydaratumumab, an anti-CD38 monoclonal antibody approved alsofor heavily pre-treated pts who have exhausted all other therapeutic options. Patients and Methods. We report the experience of the Multiple Myeloma GIMEMA Lazio Group in 50 relapsed/refractory MM pts treated with daratumumab as monotherapy. Twenty-nine pts (58%) were men and 21 (32%) women. According to the ISS,24 pts (48%) were ISS I, 11 (22%) ISS II, 7 (14%) ISS III and 8(16%)not evaluable. According toDurie & Salmon, 20 pts (40%) were 1 A, 2 (4%) 1 B, 12 (24%) II A, 1 (2%) II B,7 (14%) III A, 3 (6%) III B and 5 (10%) not evaluable. Isotype IgG-k was found in 21 pts (42%), IgG-λ in 13 (26%), IgA-k in 6 (12%), IgA-λ in 3 (6%), micromolecular k in 5 (10%) andmicromolecular λ in 2 (4%). Median age was 62.3 years (range, 43.1 - 85.7); 32 pts (64%) were refractory to the last line of therapy; 26 (52%) had previously received a stem cell transplant (13 single autologous, 12 tandem autologous and one an autologous followed by an allogeneic transplant). After a median follow-up from diagnosis of 54.5 months (range 1.0 - 203.0) and a median of 3 previous lines of therapy (range 2 - 8), pts received a median of 3 cycles (range 1 - 23) of daratumumab. Results.Forty-seven pts (94%) performed at least one cycle and were evaluable for response. The overall response rate was 74%; in particular, 2 pts obtained a CR (4.2%), 3 pts a VGPR (6.3%), 17 pts a PR (36.2%) and 15 pts a SD (32%), while 10 pts (21.3%) presented a PD. After a median follow-up of 5.3 months (range 1 - 31) ,24 pts(65%) were still in response and alive, one pt (5.8%) died in PR due to post-allograft GVHD and 12 (32%) experienced a PD (1 CR, 1 VGPR, 6 PR and 4 SD). Seven (19%) pts died and 30 (81%) are still alive. With regard to the 3 pts not evaluable for response, 2 died early and 1 has not yet completed the first cycle. The median time to response, duration of response, progression-free survival and overall survival were 1.5 months (range 1.0 - 6.0), 6.7 months (95% CI, 4.14 - 14.21), 5.7 months (95% CI, 3.26 - 13.75) and 22.5 months (95% CI, 11.6 - 36.1), respectively. Daratumumab was well tolerated; the most common adverse events, of any grade, were infections in 20 pts (42.0%) and anaemia in 21 pts (44.0%), which did not lead to treatment discontinuation. Infusion-related reactionswere observed in 7pts (14.8%), grade I-II (4 pts), grade III (3 pts). Conclusions.Daratumumab monotherapy is an effective strategy for heavily pre-treated and refractory pts with multiple myeloma, with a favorable safety profile. This treatment option needs to be considered for pts not eligible for combination therapy of daratumumab with bortezomib or lenalidomide, recently approved also in our country. Disclosures Vozella: Takeda Oncology; Amgen: Honoraria. Annibali:Celgene; Takeda; Amgen, Janssen Cilag: Honoraria. Caravita di Toritto:Johnson & Johnson: Other: Advisory Board, Travel and Accomodation EHA; Amgen: Other: Advisory Board; Bristol-Myers Squibb: Honoraria, Other: Travel and Accomodation EMN; Takeda: Other: Advisory Board; Celgene: Other: Advisory Board, Travel and Accomodation ASH, Research Funding. Foà:NOVARTIS: Speakers Bureau; JANSSEN: Other: ADVISORY BOARD, Speakers Bureau; CELGENE: Other: ADVISORY BOARD, Speakers Bureau; GILEAD: Speakers Bureau; AMGEN: Other: ADVISORY BOARD; INCYTE: Other: ADVISORY BOARD; CELTRION: Other: ADVISORY BOARD; ABBVIE: Other: ADVISORY BOARD, Speakers Bureau; ROCHE: Other: ADVISORY BOARD, Speakers Bureau. Petrucci:Takeda Oncology; Amgen; Celgene; BMS; Janssen Cilag: Honoraria, Other: Advisory Board.

Abstract: We conducted a prospective, multicenter, single-arm, open-label, non-randomized, phase II study to evaluate the efficacy and safety of 90Y Ibritumomab Tiuxetan of a new approach combining induction chemotherapy with oral Fludarabine and Mitoxantrone (FM) followed by consolidation with 90Y Ibritumomab Tiuxetan for patients with previously untreated FL. Patient eligibility was represented by: age ≥ 18 years with biopsy-proven, untreated; stage II – IV FL grade I–II; WHO performance status of 0 to 2. All patients signed a written informed consent. Patients were treated with standard FM chemotherapy (Fludarabine was administered orally at the dose 40 mg/m2/day for 3 consecutive days) every 28 days for 6 cycles. Patients were restaged 4 to 8 weeks after completion of the sixth cycle of FM. Patients achieving at least a PR after 6 cycles of FM chemotherapy were eligible for consolidation with 90Y Ibritumomab Tiuxetan provided the granulocyte count was 〉 1500/μL, the platelet count 〉 100.000/μL, lymphocytes expressing the CD20 antigen and the bone marrow examination at the completion of FM demonstrated 〈 25% involvement with lymphoma. All patients were to receive a single dose of 90Y Ibritumomab Tiuxetan 14.8 MBq/kg (0.4 mCi/kg) up to a maximum dose of 1184 MBq (32 mCi). At data reporting for this abstract, 62 patients were enrolled and 41 were evaluable for response. Of these 41 patients, all are evaluable for induction FM regimen and 19 of them also are evaluable after 90Y Ibritumomab Tiuxetan treatment. 15 were male and 26 female; the median age was 52.5 years (range 36–70); 5 were stage II, 12 stage III, and 24 stage IV. After the FM treatment the OR rate was 100%, including 73% complete remissions (CR + CRu) and 27% PR. Time to event analyses, including TTP and duration of response are pending further follow-up. Treatment was well tolerated; grade ≥ 3 AEs were seen in 20 patients; the most common grade ≥ 3 AEs was neutropenia. Among the actual 19 evaluable patients subsequentially treated with 90Y Ibritumomab Tiuxetan, 3/5 (60%) patients improved their remission status from PR to CR. The 90Y Ibritumomab Tiuxetan toxicity included grade ≥ 3 hematologic AEs in 12 patients. These preliminary data indicate: 1) FM regimen including oral fludarabine presents the same activity of i.v. formulation one without significant gastrointestinal toxicity and with a better patient compliance; 2) feasibility, tolerability, and efficacy of the FM plus 90Y Ibritumomab Tiuxetan regimen for untreated FL. Final efficacy and safety data will be presented.

Abstract: High-dose (200 mg/m2, MEL200) and intermediate-dose melphalan (100 mg/m2, MEL100) showed significant activity in myeloma. In a phase 3 study, 298 patients were randomly assigned to receive 2 autologous transplantations after conditioning with MEL200 or MEL100. Ninety-six of 149 (64%) completed MEL200 and 103 of 149 (69%) MEL100. Best response to MEL200 was: complete remission 22 of 149 (15%); partial remission 95 of 149 (64%), for an overall response rate of 79%. Best response to MEL100 was: complete remission 12 of 149 (8%); partial remission 95 of 149 (64%), for an overall response rate of 72%. Overall survival did not differ (P = .13); median progression-free survival (31.4 vs 26.2 months, P = .01), median time to progression (34.4 vs 27.0 months, P = .014) were longer in the MEL200. Treatment-related mortality was 3.1% in the MEL200 and 2.9% in the MEL100 group. Severe neutropenia and infections were marginally superior, whereas severe thrombocytopenia, mucositis, gastrointestinal adverse events, and the overall occurrence of at least 1 nonhematologic grade 3 or 4 adverse event were significantly higher in the MEL200 cohort. We conclude that MEL200 leads to longer remission duration and should be considered the standard conditioning regimen for autologous transplantation. This study was registered at www.clinicaltrials.gov as #NCT00950768.

Abstract: Telomerase reverse transcriptase (TERT) is a good candidate for cancer immunotherapy because it is overexpressed in 85% of all human tumors and implicated in maintenance of the transformed phenotype. TERT-based cancer vaccines have been shown to be safe, not inducing any immune-related pathology, but their impact on tumor progression is modest. Here we show that adoptive cell therapy with the use of high-avidity T lymphocytes reactive against telomerase can control the growth of different established tumors. Moreover, in transgenic adenocarcinoma mouse prostate mice, which develop prostate cancer, TERT-based adoptive cell therapy halted the progression to more aggressive and poorly differentiated tumors, significantly prolonging mouse survival. We also demonstrated that human tumors, including Burkitt lymphoma, and human cancer stem cells, are targeted in vivo by TERT-specific cytotoxic T lymphocytes. Effective therapy with T cells against telomerase, different from active vaccination, however, led to autoimmunity marked by a consistent, although transient, B-cell depletion in primary and secondary lymphoid organs, associated with alteration of the spleen cytoarchitecture. These results indicate B cells as an in vivo target of TERT-specific cytotoxic T lymphocytes during successful immunotherapy.

Abstract: In Philadelphia-positive (Ph+) Acute Lymphoblastic Leukemia (ALL) patients (pts), resistance to tyrosine kinase inhibitors (TKIs) is frequently associated with the selection of one or more mutations in the BCR-ABL1 kinase domain (KD). The swift emergence of mutant clones as early as during induction therapy supports the hypothesis that, at least in some cases, mutations may already be present at diagnosis. Next Generaton Sequencing (NGS) has been proposed as an alternative to Sanger sequencing (seq) for BCR-ABL1 KD mutation screening because of its greater sensitivity and accuracy, but no studies have so far evaluated its prospective use in Ph+ ALL. Between 2015 and 2018, we have used NGS in parallel to Sanger seq to analyze a consecutive series of 126 Ph+ ALL pts who were newly diagnosed (n=39) or who had relapsed/refractory disease (n=87) on TKI therapy. In 22 cases, both bone marrow and peripheral blood were analyzed and compared. NGS of ≈400bp amplicons generated by nested RT-PCR was performed on a Roche GS Junior (until April 2017) or on an Illumina MiSeq (from May 2017 on). Read alignment and variant calling (with a lower limit set to 3%) were done with the AmpSuite software (SmartSeq srl). When multiple mutations mapped within the same sequence reads, assessment of cis vs trans configuration was done correcting for the probability of PCR recombination. Three out of 39 (7.7%) de novo Ph+ ALL pts had low burden point mutations detectable by NGS: one had a V289A (variant frequency, 3.4%); one had a D276G (4.0%) and a F359V (3.5%); one had an E255K mutation (3.3%). The first pt was enrolled in the GIMEMA LAL1811 study of frontline ponatinib; the second and the third pts were enrolled in the GIMEMA D-ALBA study of frontline sequential treatment with dasatinib and blinatumomab. All pts achieved molecular remission, consistently with the mutations being sensitive to the TKIs received. The 35INS insertion/truncation mutant was detected in 27 (69%) pts, who all have so far achieved molecular remission. This is in line with the report by O'Hare et al (Blood 2011) suggesting that the 35INS variant is kinase-inactive and does not contribute to TKI resistance. For this reason, the 35INS was excluded from subsequent analyses. Relapsed/refractory pts positive for mutations by Sanger seq were 57 (65%); those positive for mutations by NGS were 69 (79%). Fifty-six out of 87 (49%) pts had 〉 1 mutation (up to 13) detected by NGS. NGS identified low burden mutations (i.e., mutations present in a proportion of transcripts between 3 and 20%) in 12 pts who were negative for mutations by Sanger seq. Most importantly, NGS provided a more accurate picture of BCR-ABL1 mutations status in 40 (46%) pts who turned out to have one or more low burden mutations in addition to the dominant mutation(s) detectable by Sanger seq. In all cases, each low burden mutation detected by NGS could be recognized as poorly sensitive either to the TKI the pt was receiving at the time of testing, or to the previous TKI. The clonal nature of NGS-based analysis further proved its utility i) in 4 pts where Sanger seq had shown 2 base substitutions in the same codon so that the actual amino-acid change(s) were impossible to infer (a ponatinib-resistant pt with a T315M mutation, 2 dasatinib-resistant pts with various combinations of F317I, F317C and/or F1317L, a dasatinib-resistant pt with 2 different nucleotide substitutions both leading to the V299L), and ii) in 48/56 pts who had ≥2 mutations whose clonal configuration could not be resolved. Twenty-eight out of these 48 pts were found to carry one or more (up to 3) compound mutants. Compound mutants were more common in pts who had failed ≥2 lines of therapy, whereas polyclonality was more common in pts who had failed first line therapy. The most frequent compound mutants were T315I+E255K and T315I+E255V. Interestingly, the latter was associated with poor or no response to ponatinib. Our results in a relatively large series of Ph+ ALL pts suggest that an NGS-based approach provides a more accurate characterization of the complexity of BCR-ABL1 KD mutation status, including compound mutants some of whom may be poorly sensitive even to ponatinib. Mutations may already be detected at the time of diagnosis. It remains to be assessed whether more sensitive techniques like digital PCR may identify a greater number of pts with pre-therapy mutations and whether the detection of pre-therapy mutations may be used to guide 1st-line treatment selection. Disclosures Soverini: Incyte Biosciences: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Consultancy. Pagano:Gilead: Speakers Bureau; Basilea: Speakers Bureau; Merck: Speakers Bureau; Janssen: Speakers Bureau; Pfizer: Speakers Bureau. Abruzzese:Ariad: Consultancy; BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy. Martinelli:Roche: Consultancy; Celgene: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy; Pfizer: Consultancy, Speakers Bureau; Novartis: Speakers Bureau; Abbvie: Consultancy; Janssen: Consultancy; Ariad/Incyte: Consultancy; Amgen: Consultancy. Cavo:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees.