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Patients with primary central nervous system lymphoma (PCNSL) are treated with high-dose methotrexate-based chemotherapy, which requires hospitalization and extensive expertise to manage related toxicity. The use of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) could overcome these difficulties, but blood-brain barrier (BBB) penetration of related drugs is poor. Tumor necrosis factor-a coupled with NGR (NGR-hTNF), a peptide targeting CD13+ vessels, induces endothelial permeabilization and improves tumor access of cytostatics. We tested the hypothesis that NGR-hTNF can break the BBB, thereby improving penetration and activity of R-CHOP in patients with relapsed/refractory PCNSL (NCT03536039). Patients received six R-CHOP21 courses, alone at the first course and preceded by NGR-hTNF (0.8 µg/m2) afterward. This trial included 2 phases: an “explorative phase” addressing the effect of NGR-hTNF on drug pharmacokinetic parameters and on vessel permeability, assessed by dynamic contrast-enhanced magnetic resonance imaging and 99mTc-diethylene-triamine-pentacetic acid–single-photon emission computed tomography, and the expression of CD13 on tumor tissue; and an “expansion phase” with overall response rate as the primary end point, in which the 2-stage Simon Minimax design was used. At the first stage, if =4 responses were observed among 12 patients, the study accrual would have continued (sample size, 28). Herein, we report results of the explorative phase and the first-stage analysis (n = 12). CD13 was expressed in tumor vessels of all cases. NGR-hTNF selectively increased vascular permeability in tumoral/peritumoral areas, without interfering with drug plasma/cerebrospinal fluid concentrations. The NGR-hTNF/R-CHOP combination was well tolerated: there were only 2 serious adverse events, and grade 4 toxicity was almost exclusively hematological, which were resolved without dose reductions or interruptions. NGR-hTNF/R-CHOP was active, with 9 confirmed responses (75%; 95% confidence interval, 51-99), 8 of which were complete. In conclusion, NGR-hTNF/R-CHOP was safe in these heavily pretreated patients. NGR-hTNF enhanced vascular permeability specifically in tumoral/peritumoral areas, which resulted in fast and sustained responses.

Patients with primary central nervous system lymphoma (PCNSL) are treated with high-dose methotrexate-based chemotherapy, which requires hospitalization and extensive expertise to manage related toxicity. The use of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) could overcome these difficulties, but blood-brain barrier (BBB) penetration of related drugs is poor. Tumor necrosis factor-α coupled with NGR (NGR-hTNF), a peptide targeting CD13+vessels, induces endothelial permeabilization and improves tumor access of cytostatics. We tested the hypothesis that NGR-hTNF can break the BBB, thereby improving penetration and activity of R-CHOP in patients with relapsed/refractory PCNSL (NCT03536039). Patients received six R-CHOP21 courses, alone at the first course and preceded by NGR-hTNF (0.8 μg/m2) afterward. This trial included 2 phases: an “explorative phase” addressing the effect of NGR-hTNF on drug pharmacokinetic parameters and on vessel permeability, assessed by dynamic contrast-enhanced magnetic resonance imaging and 99mTc-diethylene-triamine-pentacetic acid–single-photon emission computed tomography, and the expression of CD13 on tumor tissue; and an “expansion phase” with overall response rate as the primary end point, in which the 2-stage Simon Minimax design was used. At the first stage, if ≥4 responses were observed among 12 patients, the study accrual would have continued (sample size, 28). Herein, we report results of the explorative phase and the first-stage analysis (n = 12). CD13 was expressed in tumor vessels of all cases. NGR-hTNF selectively increased vascular permeability in tumoral/peritumoral areas, without interfering with drug plasma/cerebrospinal fluid concentrations. The NGR-hTNF/R-CHOP combination was well tolerated: there were only 2 serious adverse events, and grade 4 toxicity was almost exclusively hematological, which were resolved without dose reductions or interruptions. NGR-hTNF/R-CHOP was active, with 9 confirmed responses (75%; 95% confidence interval, 51-99), 8 of which were complete. In conclusion, NGR-hTNF/R-CHOP was safe in these heavily pretreated patients. NGR-hTNF enhanced vascular permeability specifically in tumoral/peritumoral areas, which resulted in fast and sustained responses.

BACKGROUND

Gentner: Genenta Science: Consultancy, Equity Ownership, Research Funding. Mazzoleni:Genenta Science: Employment, Equity Ownership. Russo:Genenta Science: Consultancy, Equity Ownership. Naldini:Genenta Science: Consultancy, Equity Ownership; Magenta Therapeutics: Equity Ownership; San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), a joint venture between Fondazione Telethon and Ospedale San Raffaele (OSR): Other: Wiskott-Aldrich Syndrome (WAS) gene therapy was licensed to GlaxoSmithKline (GSK) in 2014. It was then licensed to Orchard Therapeutics (OTL) in April 2018. OTL is the current sponsor of the clinical trial..

Introduction

Bonini: Molmed SpA: Consultancy; TxCell: Membership on an entity's Board of Directors or advisory committees. Ciceri:MolMed SpA: Consultancy.

No relevant conflicts of interest to declare.

Broome: Alexion Pharmaceuticals: Consultancy, Honoraria, Research Funding.

Broome: Alexion Pharmaceuticals: Consultancy, Honoraria, Research Funding.

Infections are the major cause of treatment-related morbidity and mortality in hematological patients, mostly after allogeneic hematopoietic stem cell transplantation (HSCT). Although the proportion of infection-related deaths has decreased in the past two decades, the alarming emergence of multidrug resistant (MDR) gram-negative pathogens, increasingly reported from various cancer treatment centers, represents a significant challenge. Dramatic infection-related mortality (64.4%) have been observed in allogeneic HSCT, due to carbapenem-resistant Klebsiella pneumoniae(CRKp). Timely microbiological diagnosis, active surveillance and early therapeutic strategies represent critical aspects for the management of MDR infections after allogeneic HSCT.

Broome: Alexion Pharmaceuticals: Honoraria.

Broome: Alexion Pharmaceuticals: Honoraria.

Post transplant thrombotic microangiopathy (PT-TMA) has been recognized for over 25 years. The exact incidence of PT-TMA in small bowel transplant (SBT) patients is unknown with reports varying from 4% to greater than 30%. One of the contributors to the differences in reported occurrence rates is the continued debate regarding the definition of PT-TMA. There is a growing consensus that PT-TMA is complement mediated and therefore can be defined by the same criteria as atypical hemolytic uremic syndrome (aHUS). AHUS is a complement mediated TMA defined by microangiopathic hemolytic anemia, thrombocytopenia (TCP), and end organ damage. We have previously demonstrated that the initiation of eculizumab in post-transplant aHUS (PT-aHUS) has led to improved outcomes in these patients. We believe that establishing reliable diagnostic criteria that can be utilized in the post transplant period will lead to earlier recognition and treatment which will decrease the high mortality rate associated with PT- aHUS.

Martinelli: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy; ARIAD: Consultancy.

Bonini: MolMed S.p.A.: Consultancy. Bordignon:MolMed: Employment.

Systemic mastocytosis (SM) is a rare myeloproliferative neoplasm characterized by proliferation and hyperactivation of clonal mast cells. Clinical manifestations are heterogeneous and encompass cutaneous lesions, gastrointestinal alterations, osteoporosis, anaphylaxis and involvement of bone marrow and other organs due to neoplastic mast cells (MC) infiltration. As consequence, diagnosis may be difficult and patients (pts) are often evaluated by different specialists before the disease is recognized. To date, only few studies (Lim 2009, Escribano 2009, Cohen 2014) described relatively large series of pts with SM. We performed a multicentre retrospective study to evaluate clinical and biological features and therapeutic management in a large series of pts from 10 Italian centres experienced in management of SM and organized in multidisciplinary groups of specialists. We collected 455 pts diagnosed with SM according to WHO criteria. Additionally 26 pts with mastocytosis in the skin (MIS) evaluated with BM examination did not fulfil criteria for SM, leading to diagnosis of Cutaneous Mastocytosis (CM); however 2/26 pts with CM had both cKITD816V mutation and CD2/CD25 expression on MC in BM, additional 3 showed either cKITD816V or CD2/CD25. Moreover, we found 22 pts without MIS but with features of monoclonal mast cell activation syndrome. Of the 455 pts with WHO-SM (male 56%), 252 (55%) had MIS: median age at MIS diagnosis (dg) was 37 years (y) (range 0-79), while at SM dg it was 46.5 (range 18-82). Time from onset of MIS to dg of SM was 9 y (range 0-43). In 18/252 pts (7%) MIS occurred before age of 18 y (median 9, range 0-17) and persisted over childhood. Median age at dg of SM without MIS (203/455 pts, 45%) was older: 54 y, range 19-79 (p<0.0001). First manifestations of SM were MIS in 46.5% of pts, anaphylaxis in 47.8%, mediator related symptoms in 6.4%, osteoporosis/bone lesions in 5.2%, organomegaly in 3.4%, hematologic alterations in 0.4%. Anaphylaxis was observed in 76/252 (30.1%) pts with MIS, of which 23 had tryptase <20 mcg/L. BM multifocal infiltrates of MC were present in 61.6% of pts, while in 38.4% dg was performed only by using minor criteria. cKIT D816V mutation was detected in BM of 394/432 analysed pts (91.2%). Three D816V-negative pts had different cKIT mutations: M541L, D816H and K546K. In peripheral blood cKIT D816V was evaluated in 165 pts and found in 49.7%. CD2 and/or CD25 expressing MC were found in 99% of pts of the 426 evaluated. Mean tryptase value at dg was 75.9±263 mcg/L. SM subtypes were indolent SM (ISM) 402/455 (88.4%), of which 140 isolated bone marrow mastocytosis (BMM) (34.5% of ISM) and 34 smoldering SM (SSM) (8.4% of ISM), aggressive SM (ASM) 32/455 (7%), SM associated with hematological non mast cell disorders (SM-AHNMD) 20/455 (4.4%), mast cell leukemia (MCL) 1/455 (0.2%). In SM-AHNMD the associated hematologic disease was chronic myelomonocytic leukemia (6/20, 30%), non-Hodgkin lymphoma and refractory anemia with ring sideroblasts and thrombocytosis (3/20 each, 15%), essential thrombocythemia and not otherwise characterized myeloproliferative neoplasm (2/20 each, 10%), myelodysplastic syndrome, myelofibrosis, multiple myeloma and acute myeloid leukemia (AML) (1/20 each, 5%). Median follow up was 23 months (mo), range 2-289. At last follow up, 27/455 pts died (5.9%). 52% of pts had ASM, 18.5% SM-AHNMD, 14.7% SSM, 7.4% ISM and 3.7% each MCL and BMM. Causes of death were disease progression in 21/27 pts (77.8%), other solid neoplasms in 3/27 (11.1%), arterial thrombosis in 2/27 (9.5%), cerebral haemorrhage in 1/27 (3.7%). Disease progression consisted in evolution to AML in 6 pts with ASM, 1 pts with SSM and 1 pts with SM-AHNMD; median time to progression to AML was 30 mo (range 13-149); 2 pts developed other AHNMD: chronic myeloid leukemia and myelofibrosis. 178/455 pts (39%) were treated with anti MC mediators therapies. Of the 60/455 (13%) treated with cytostatic therapy 47% had ASM, 12% SM-AHNMD, 2% MCL, 35% ISM of which 38% were SSM. The ISM cohort was treated mainly due to severe osteoporosis with vertebral fractures not C-findings or disease evolution. First line therapy was interferon (28.3%), hydroxyurea (20%), midostaurine (18.3%), imatinib (13.3%), cladribin (8.3%), dasatinib (6.7%) and masitinib (5%). This is one of the largest series reporting pts with SM that may provide useful information for clinical management of pts with this probably underestimated “rare” disease.

Patients who receive non-renal solid organ transplants have a reported 4-30% incidence of post transplant thrombotic microangiopathy (PT-TMA). The development of PT- TMA is associated with a significant increase in early mortality when compared to patients with no PT-TMA. Mortality rates as high as 70% are associated with PT-TMA in spite of plasma exchange therapy. The factors which contribute to this high mortality are poorly understood. New findings suggest that this form of TMA is complement mediated and can be classified as PT-aHUS. We and others have reported the clinical and laboratory benefits of treating PT-aHUS with eculizumab. There are suggestions of a link between PT-TMA and decreased graft survival although the mechanism is not well understood. Theories include: 1) chronic ischemia from TMA, 2) chronic/low grade antibody mediated rejection (perhaps contributed to by alloimmunization from transfusions) and 3) direct damage to graft mediated by complement. The role that multiple post transplant transfusions plays in poor overall and/or poor graft survival in these patients has not been evaluated, but is intriguing.

IntroductionHaematopoietic stem cell transplantation (HSCT) is the only curative option for patients (pts) affected by high-risk haematological diseases (HRHD). However, the availability of a match donor is still an unmet-medical need. Recently alternative donor transplantations have been broadly exploited, reaching results similar to transplants from a well match donor. Anyway, whoever the donor is, the most important complication remains Graft-versus-Host Disease(GvHD).

Broome: Alexion Pharmaceuticals: Honoraria, Speakers Bureau. Off Label Use: Eculizumab for the treatment of calcineurin induced TMA.

Thrombotic microangiopathy (TMA) is seen in up to 30% of patients receiving solid organ transplantation and almost always occurs in the setting of calcineurin inhibitor (CNI) therapy. The underlying pathophysiology of calcineurin induced TMA is poorly understood. Long term follow up in non renal transplant patients with TMA suggests that in spite of plasma exchange therapy the 1 year mortality following TMA is up to 70%.

Definition of leukemia remission requires the lack of disease markers at sub-microscopic level. This is highly important after a potentially curative approach as allogeneic hematopoietic stem cell transplant (HSCT), where early detection of relapse at molecular level may lead to modulation of immunosuppressive therapy or donor lymphocyte infusion (DLI). In AML various approaches has been used to define MRD, but still the majority of AML cases do not have a useful and sensitive MRD marker. Over-expression of Wilms' tumor gene 1 (WT1) in leukemic blasts has been reported in >80% of AML and >40% of MDS. Physiologic hematopoietic stem cell compartments also express WT1, however, a ‘malignant’ WT1 expression can be clearly distinguished based on quantitative detection methods such as semiquantitative RT-PCR. Quantification of WT1 expression levels can detect frequencies of leukemic cells in bone marrow (BM) and peripheral blood (PB) as low as 10-3 and 10-5, respectively. Therefore WT1 expression levels provide a new marker for leukemic blast cells regardless of the type of leukemia especially in the relevant percentage of patients that lacks a specific molecular marker of their disease and thus may be a useful marker MRD and may predict the relapse after allogeneic HSCT.We measured quantitative expression of WT1 at diagnosis, before and after allogeneic transplant monthly for the first six months and then every three months. The quantitative assessment of the WT1 transcript amount was performed by real-time quantitative polymerase chain reaction (RQ-PCR).Our study included 19 AML and 6 MDS pts who underwent allogeneic HSCT in our Institute between 12/2007 and 6/2009. Median age at diagnosis was 49 years (range 22-68). Bone marrow samples at diagnosis showed a WT1 median expression level of 5851.66 copies (range 77.98-31203.57). Fifteen pts (60%) had a specific cytogenetic marker that could allow MRD monitoring. At HSCT 17 pts (68%) were in CR, 5 (20%) had a refractory or relapsed disease, while 3 (12%) were transplanted upfront. Six pts (24%) received grafts from a matched sibling donors, 6 (24%) were transplanted from a matched unrelated donor (MUD), 10 (40%) from a familiar haploidentical donor and 3 (12%) received a cord blood unit. Myeloablative conditioning regimen consisted of Treosulfan 42 g/sqm, Fludarabine 150 mg/sqm, ALG 30 mg/kg and Rituximab 500 mg (last two drugs only for alternative donors). After HSCT a rapid decline of WT1 expression levels was observed in all pts that obtained or maintained a condition of CR. Two pts (8%) relapsed and both had an increase in WT1 expression before relapse. In the first relapsed pt, analysis of WT1 showed a dramatically increase between pre transplant level and day +28, while STR showed 100% donor chimerism. Relapse occurred on day +43, still on IST, with 69% of blast at AM evaluation and 40% donor chimerism. This pt was successfully reinduced with chemotherapy followed by allogeneic PBSC infusion without GvHD profilaxys obtaining a rapid reduction of WT1 (43.66). The pt developed GvHD that required a new IST, confirming a strong immune-surveillance of HSCT. The second pt was still on immunosuppressive treatment (IST) at the time of relapse (+136). WT1 in BM on day +30 was 30 cp and then increased gradually to 167 and 190 cp on day +67 and +102, respectively. Cytogenetic analysis and STR chimerism still showed a cCR with 100% donor chimerism. At relapse AM showed 10% blasts, WT1 expression level was 7447 cp with >95% donor chimerism. IST was discontinued and one month later WT1 expression level decreased to 1640 with >95% donor chimerism. In this situation we reasoned that DLI was the best available treatment. The total dose of donor T cell infused was 5 ×105 CD3/Kg. This procedure allowed an immune-mediated leukemia control with reduction of WT1 (1.58), cCR and 100% donor chimerism.These data show that WT1 may be useful as a non-specific leukemia marker for monitoring MRD in AML and MDS after allogeneic HSCT and should enable the detection of early relapse allowing intervention at a more favourable stage than at overt relapse. We observed a complete concordance between WT1 expression levels and status of AML before and after allogeneic HSCT. Based on these results cases with increase of WT1 levels after HSCT and without GVHD may be candidate to immune intervention such as discontinuation of immunosuppression and/or DLI.Bonini: MolMed S.p.A.: Consultancy.

the majority of AML and poor risk MDS cases in the elderly (>60 years) are resistant to induction chemotherapy or relapse after initial response; thereafter, most of these patients (pts) receive only supportive treatments, with an expected survival of few weeks. Allogeneic (allo) stem cell transplantation (SCT) could be the only potentially salvage strategy; actually, for the high probability of letal toxicites due to the conditioning regimen, acute graft-versus-host disease (aGvHD) and infections, these pts are rarely offered this procedure.Since 2005, we have transplanted 12 pts, age>60, with refractory or relapsed AML/MDS, from an allogeneic donor. Data on feasibility and outcome are here reported.to retrospectively evaluate data on alloSCT in elderly pts with refractory or relapsed AML and MDS, transplanted at our Institute.period 9/2005 to 4/2009, 12 pts, median age 65 (61-72). Performance status (Karnofsky): median 90% (80-100), HCT-CI: median score 1 (0-4). Diagnosis (WHO): AML 3, AMLMD 4, RAEB2 2, MDS/MPD 2, therapy-related AML 1. Median number of chemo cycles before SCT: 2 (1-7), all pts received at least 1 cycle with intermediate or high-dose cytarabine, 2 pts also received an autologous SCT. Donors: matched sibling 2, matched unrelated 2, related haploidentical 7, cord blood 1. Disease status at SCT: primary refractory 7, relapsed 5. Conditioning regimen: treosulfan (TREO) 14 g/sqm for 3 days, fludarabine (FLU) 30 mg/sqm for 5 days, ATG 10 mg/kg for 3 days for SCT from alternative donors. GvHD prophylaxis: T-cell depletion in 2 cases, cyclosporine (CSA)/methotrexate in 7, rapamycin/mycophenolate mofetil (MMF) in 3.11/12 (92%) pts engrafted and were in CR at day +30, with 95-100% donor chimerism (VNTR). Deaths within day 30 and day 100 were 0 and 3 (25%), respectively. Acute GvHD: 6 pts (55%), grade II (3) or III (3), only of skin in 3 cases, skin+liver in 1, only intestinal in 2. Relapses were 4 (36%). Overall TRM was 25% (3 pts), with all deaths due to infections during immunosuppression for aGVHD; 5 more pts died because of disease progression. Median OS from SCT of all 12 pts was 180 (56-1150) days, DFS (11 pts) was 128 (24-1114) days. At last follow-up (FU) 4 pts (33%) are alive, all in CR with a median FU of 406 (128-1150) days.alloSCT proved to be feasible in our elderly pts with AML/MDS refractory to induction or relapsed after initial complete remission. Early letal toxicities, due to the conditioning treatment, were absent; aGVHD, infections and relapses were the principal causes of mortality. Up to now, prolonged survival (>1 year) free from disease has been obtained in 25% of pts; of the 4 pts alive in CR, only 1 is receiving immunosuppression (CSA), for chronic GVHD. In conclusion, the TREO-FLU association showed a reduced-toxicity profile in these frail pts and a substantial anti-leukemic effect. Better prevention of aGVHD should be obtained, expecially after SCT from alternative donors, possibly with the rapamycin/MMF combination, which we are currently investigating at our Institute. AlloSCT after TREO-FLU conditioning can be considered an effective option for AML/MDS elderly pts with active disease after failure of previous intensive treatments.bonini: MolMed S.p.A.: Consultancy.

Abstract 4488

Abstract 4318