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Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337S mutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337S intestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ–induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3, and Mefv predominated in neutrophils, whereas Nlrc4 and Il18 were distinctly epithelial. Demonstrating the importance of free IL-18, Il18 transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337S mice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18–driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.

Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337Smutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337Sintestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ–induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3,and Mefvpredominated in neutrophils, whereas Nlrc4and Il18were distinctly epithelial. Demonstrating the importance of free IL-18, Il18transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337Smice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18–driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.

Reduced-intensity conditioning has improved survival after hematopoietic stem cell transplantation (HSCT) for hemophagocytic lymphohistiocytosis (HLH) at the cost of more frequent mixed chimerism. The minimum level of donor chimerism (DC) required to prevent HLH reactivation in humans remains to be determined. In a multicenter retrospective study, 103 patients transplanted for hereditary HLH (2000-2013) and DC permanently or transiently <75% (overall, CD3+, CD56+) were analyzed regarding DC, specific immunologic function, occurrence of systemic reactivations (≥5/8 HLH criteria), partial systemic flares (<5 criteria and HLH-directed treatment), isolated central nervous system reactivations, and management. Recurrence was reported in 18 patients (systemic reactivation n = 11, partial flare n = 3, isolated central nervous system reactivation n = 4). Ten events occurred during profound immune suppression before day 180 (median DC, 10%; range, 1-100%; CD3+ if available, otherwise overall DC), which renders a differentiation between secondary post-HSCT HLH and HLH related to the genetic defect difficult. Eight events occurred between 0.5 and 6.7 years post-HSCT (median DC, 13%; range, 0-30%). In 5 patients, overall and lineage-specific DC were ≤10% for >6 months (median, 5.1; range, 1.1-10 years) without reactivation. A second HSCT was performed in 18 patients (median, DC 4%; range, 0-19%). Death from reactivation occurred in 4 patients (22% of recurrences). Six patients died of transplant complications following a second HSCT (33% of second HSCT). We conclude that a DC >20%-30% is protective against late reactivation. Lower levels do not, however, inescapably result in recurrences. The decision for or against second HSCT must be based on a thorough risk assessment.

Reduced-intensity conditioning has improved survival after hematopoietic stem cell transplantation (HSCT) for hemophagocytic lymphohistiocytosis (HLH) at the cost of more frequent mixed chimerism. The minimum level of donor chimerism (DC) required to prevent HLH reactivation in humans remains to be determined. In a multicenter retrospective study, 103 patients transplanted for hereditary HLH (2000-2013) and DC permanently or transiently <75% (overall, CD3+, CD56+) were analyzed regarding DC, specific immunologic function, occurrence of systemic reactivations (≥5/8 HLH criteria), partial systemic flares (<5 criteria and HLH-directed treatment), isolated central nervous system reactivations, and management. Recurrence was reported in 18 patients (systemic reactivation n = 11, partial flare n = 3, isolated central nervous system reactivation n = 4). Ten events occurred during profound immune suppression before day 180 (median DC, 10%; range, 1-100%; CD3+if available, otherwise overall DC), which renders a differentiation between secondary post-HSCT HLH and HLH related to the genetic defect difficult. Eight events occurred between 0.5 and 6.7 years post-HSCT (median DC, 13%; range, 0-30%). In 5 patients, overall and lineage-specific DC were ≤10% for >6 months (median, 5.1; range, 1.1-10 years) without reactivation. A second HSCT was performed in 18 patients (median, DC 4%; range, 0-19%). Death from reactivation occurred in 4 patients (22% of recurrences). Six patients died of transplant complications following a second HSCT (33% of second HSCT). We conclude that a DC >20%-30% is protective against late reactivation. Lower levels do not, however, inescapably result in recurrences. The decision for or against second HSCT must be based on a thorough risk assessment.

Genetic disorders affecting biogenesis and transport of lysosome-related organelles are heterogeneous diseases frequently associated with albinism. We studied a patient with albinism, neutropenia, immunodeficiency, neurodevelopmental delay, generalized seizures, and impaired hearing but with no mutation in genes so far associated with albinism and immunodeficiency. Whole exome sequencing identified a homozygous mutation in AP3D1 that leads to destabilization of the adaptor protein 3 (AP3) complex. AP3 complex formation and the degranulation defect in patient T cells were restored by retroviral reconstitution. A previously described hypopigmented mouse mutant with an Ap3d1 null mutation (mocha strain) shares the neurologic phenotype with our patient and shows a platelet storage pool deficiency characteristic of Hermansky-Pudlak syndrome (HPS) that was not studied in our patient because of a lack of bleeding. HPS2 caused by mutations in AP3B1A leads to a highly overlapping phenotype without the neurologic symptoms. The AP3 complex exists in a ubiquitous and a neuronal form. AP3D1 codes for the AP3δ subunit of the complex, which is essential for both forms. In contrast, the AP3β3A subunit, affected in HPS2 patients, is substituted by AP3β3B in the neuron-specific heterotetramer. AP3δ deficiency thus causes a severe neurologic disorder with immunodeficiency and albinism that we propose to classify as HPS10.

Genetic disorders affecting biogenesis and transport of lysosome-related organelles are heterogeneous diseases frequently associated with albinism. We studied a patient with albinism, neutropenia, immunodeficiency, neurodevelopmental delay, generalized seizures, and impaired hearing but with no mutation in genes so far associated with albinism and immunodeficiency. Whole exome sequencing identified a homozygous mutation in AP3D1that leads to destabilization of the adaptor protein 3 (AP3) complex. AP3 complex formation and the degranulation defect in patient T cells were restored by retroviral reconstitution. A previously described hypopigmented mouse mutant with an Ap3d1null mutation (mocha strain) shares the neurologic phenotype with our patient and shows a platelet storage pool deficiency characteristic of Hermansky-Pudlak syndrome (HPS) that was not studied in our patient because of a lack of bleeding. HPS2 caused by mutations in AP3B1Aleads to a highly overlapping phenotype without the neurologic symptoms. The AP3 complex exists in a ubiquitous and a neuronal form. AP3D1codes for the AP3δ subunit of the complex, which is essential for both forms. In contrast, the AP3β3A subunit, affected in HPS2 patients, is substituted by AP3β3B in the neuron-specific heterotetramer. AP3δ deficiency thus causes a severe neurologic disorder with immunodeficiency and albinism that we propose to classify as HPS10.

In patients with hypogammaglobulinemia secondary to chronic lymphocytic leukemia (CLL) or multiple myeloma (MM), intravenous immune globulin (IVIg) may be administered to reduce the risk of infection. Since 2013, IVIg products have carried a boxed safety warning about the risk of thromboembolic events (TEEs), with TEEs reported in 0.5% to 15% of patients treated with IVIg. In this retrospective cohort study of older patients with CLL or MM identified from the Surveillance, Epidemiology, and End Results-Medicare Linked Database, we assessed rates of clinically serious TEEs in 2724 new users of IVIg and a propensity-matched comparison group of 8035 nonusers. For the primary end point, arterial TEE, we observed a transient increased risk of TEE during the day of an IVIg infusion and the day afterward (hazard ration = 3.40; 95% confidence interval [CI]: 1.25, 9.25); this risk declined over the remainder of the 30-day treatment cycle. When considered in terms of absolute risk averaged over a 1-year treatment period, the increase in risk attributable to IVIg was estimated to be 0.7% (95% CI: −0.2%, 2.0%) compared with a baseline risk of 1.8% for the arterial TEE end point. A statistically nonsignificant risk increase of 0.3% (95% CI: −0.4%, 1.5%) compared with a baseline risk of 1.1% was observed for the venous TEE end point. Further research is needed to establish the generalizability of these results to patients receiving higher doses of IVIg for other indications.

In patients with hypogammaglobulinemia secondary to chronic lymphocytic leukemia (CLL) or multiple myeloma (MM), intravenous immune globulin (IVIg) may be administered to reduce the risk of infection. Since 2013, IVIg products have carried a boxed safety warning about the risk of thromboembolic events (TEEs), with TEEs reported in 0.5% to 15% of patients treated with IVIg. In this retrospective cohort study of older patients with CLL or MM identified from the Surveillance, Epidemiology, and End Results-Medicare Linked Database, we assessed rates of clinically serious TEEs in 2724 new users of IVIg and a propensity-matched comparison group of 8035 nonusers. For the primary end point, arterial TEE, we observed a transient increased risk of TEE during the day of an IVIg infusion and the day afterward (hazard ration = 3.40; 95% confidence interval [CI]: 1.25, 9.25); this risk declined over the remainder of the 30-day treatment cycle. When considered in terms of absolute risk averaged over a 1-year treatment period, the increase in risk attributable to IVIg was estimated to be 0.7% (95% CI: −0.2%, 2.0%) compared with a baseline risk of 1.8% for the arterial TEE end point. A statistically nonsignificant risk increase of 0.3% (95% CI: −0.4%, 1.5%) compared with a baseline risk of 1.1% was observed for the venous TEE end point. Further research is needed to establish the generalizability of these results to patients receiving higher doses of IVIg for other indications.

Accumulation of CD3+ T-cell receptor (TCR)αβ+CD4−CD8− double-negative T cells (DNT) is a hallmark of autoimmune lymphoproliferative syndrome (ALPS). DNT origin and differentiation pathways remain controversial. Here we show that human ALPS DNT have features of terminally differentiated effector memory T cells reexpressing CD45RA+ (TEMRA), but are CD27+CD28+KLRG1− and do not express the transcription factor T-bet. This unique phenotype was also detected among CD4+ or CD8+ ALPS TEMRA cells. T-cell receptor β deep sequencing revealed a significant fraction of shared CDR3 sequences between ALPS DNT and both CD4+ and CD8+TEMRA cells. Moreover, in ALPS patients with a germ line FAS mutation and somatic loss of heterozygosity, in whom biallelic mutant cells can be tracked by absent Fas expression, Fas-negative T cells accumulated not only among DNT, but also among CD4+ and CD8+TEMRA cells. These data indicate that in human Fas deficiency DNT cannot only derive from CD8+, but also from CD4+ T cells. Furthermore, defective Fas signaling leads to aberrant transcriptional programs and differentiation of subsets of CD4+ and CD8+ T cells. Accumulation of these cells before their double-negative state appears to be an important early event in the pathogenesis of lymphoproliferation in ALPS patients.

Accumulation of CD3+T-cell receptor (TCR)αβ+CD4−CD8−double-negative T cells (DNT) is a hallmark of autoimmune lymphoproliferative syndrome (ALPS). DNT origin and differentiation pathways remain controversial. Here we show that human ALPS DNT have features of terminally differentiated effector memory T cells reexpressing CD45RA+(TEMRA), but are CD27+CD28+KLRG1−and do not express the transcription factor T-bet. This unique phenotype was also detected among CD4+or CD8+ALPS TEMRA cells. T-cell receptor β deep sequencing revealed a significant fraction of shared CDR3 sequences between ALPS DNT and both CD4+and CD8+TEMRA cells. Moreover, in ALPS patients with a germ line FASmutation and somatic loss of heterozygosity, in whom biallelic mutant cells can be tracked by absent Fas expression, Fas-negative T cells accumulated not only among DNT, but also among CD4+and CD8+TEMRA cells. These data indicate that in human Fas deficiency DNT cannot only derive from CD8+, but also from CD4+T cells. Furthermore, defective Fas signaling leads to aberrant transcriptional programs and differentiation of subsets of CD4+and CD8+T cells. Accumulation of these cells before their double-negative state appears to be an important early event in the pathogenesis of lymphoproliferation in ALPS patients.

Genetic disorders of lymphocyte cytotoxicity predispose patients to hemophagocytic lymphohistiocytosis (HLH). Reduced lymphocyte cytotoxicity has been demonstrated in Hermansky-Pudlak syndrome type 2 (HPS2), but only a single patient was reported who developed HLH. Because that patient also carried a potentially contributing heterozygous RAB27A mutation, the risk for HLH in HPS2 remains unclear. We analyzed susceptibility to HLH in the pearl mouse model of HPS2. After infection with lymphocytic choriomeningitis virus, pearl mice developed all key features of HLH, linked to impaired virus control caused by a moderate defect in CTL cytotoxicity in vivo. However, in contrast to perforin-deficient mice, the disease was transient, and all mice fully recovered and controlled the infection. An additional heterozygous Rab27a mutation did not aggravate the cytotoxicity defect or disease parameters. In the largest survey of 22 HPS2 patients covering 234 patient years, we identified only 1 additional patient with HLH and 2 with incomplete transient HLH-like episodes, although cytotoxicity or degranulation was impaired in all 16 patients tested. HPS2 confers a risk for HLH that is lower than in Griscelli or Chediak-Higashi syndrome, probably because of a milder defect in cytotoxicity. Preemptive hematopoietic stem cell transplantation does not appear justified in HPS2.

Genetic disorders of lymphocyte cytotoxicity predispose patients to hemophagocytic lymphohistiocytosis (HLH). Reduced lymphocyte cytotoxicity has been demonstrated in Hermansky-Pudlak syndrome type 2 (HPS2), but only a single patient was reported who developed HLH. Because that patient also carried a potentially contributing heterozygous RAB27Amutation, the risk for HLH in HPS2 remains unclear. We analyzed susceptibility to HLH in the pearlmouse model of HPS2. After infection with lymphocytic choriomeningitis virus, pearlmice developed all key features of HLH, linked to impaired virus control caused by a moderate defect in CTL cytotoxicity in vivo. However, in contrast to perforin-deficient mice, the disease was transient, and all mice fully recovered and controlled the infection. An additional heterozygous Rab27amutation did not aggravate the cytotoxicity defect or disease parameters. In the largest survey of 22 HPS2 patients covering 234 patient years, we identified only 1 additional patient with HLH and 2 with incomplete transient HLH-like episodes, although cytotoxicity or degranulation was impaired in all 16 patients tested. HPS2 confers a risk for HLH that is lower than in Griscelli or Chediak-Higashi syndrome, probably because of a milder defect in cytotoxicity. Preemptive hematopoietic stem cell transplantation does not appear justified in HPS2.

Background:In patients with newly-diagnosed multiple myeloma (NDMM) who receive frontline autologous stem cell transplantation (ASCT), maintenance therapy (MT) following ASCT has been shown to delay disease progression and death. Current National Comprehensive Cancer Network (NCCN) guidelines also recommend MT for patients with MM, including the use of lenalidomide, bortezomib-based regimens, or ixazomib. However, there is limited evidence on the use and outcomes associated with MT in contemporary real-world patients. The present study assessed MT treatment patterns and clinical outcomes in a real-world US cohort of patients with NDMM following ASCT.

Introduction:Infections continue to be one of the main causes of morbidity and mortality in multiple myeloma (MM) patients. Compared to the general population, MM patients have a 7-fold increased risk of bacterial infections and 10-fold risk of viral infections. The recent National Comprehensive Cancer Network (NCCN) guideline has provided guidance for prevention of cancer-related infections; however, utilization of anti-infective prophylaxis among MM patients in real-world practice has not been fully established. Daratumumab, a human IgGκ monoclonal antibody targeting CD38, is approved as monotherapy and in combination with standard-of-care regimens for newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM). The primary objective of the study was to describe the proportion of MM patients who received anti-infective prophylaxis when initiating a daratumumab-based treatment regimen.

Introduction:Despite recent treatment (tx) advances that have improved overall survival (OS), multiple myeloma (MM) remains a mostly incurable malignancy. Txs become less effective with each successive line of therapy (LOT). The rapidly evolving tx landscape has raised questions about the optimal tx sequence; recent trial data may be useful to develop and test hypotheses about tx sequencing. However, real-world (RW) data have shown that while most patients (pts) with newly diagnosed MM (NDMM) receive first-line (1L) tx, attrition rates are high in later LOT, with up to 50% of transplant ineligible (TIE) pts receiving no tx beyond 1L. As many pts will not have an opportunity to be salvaged with later LOT, achieving the longest possible progression-free survival (PFS) upfront is critical. In the MAIA trial, daratumumab (DARA), lenalidomide, and dexamethasone (D-Rd) demonstrated significant PFS (hazard ratio [HR]=0.53, P<0.0001) and OS (HR=0.68, P=0.0013) benefit vs Rd. In a subgroup of pts ≥65 years old in the SWOG S0777 study, bortezomib, lenalidomide, and dexamethasone (VRd) had no significant OS benefit vs Rd. In the absence of head-to-head studies comparing different tx sequences, clinical trial data can be used to explore different scenarios. Published models suggest that delaying DARA until later LOT is a viable tx strategy. Limitations of these models include basing conclusions on tx sequences other than those recommended in clinical guidelines, not accounting for the attrition rates from 1L to subsequent LOT and relying on inappropriate clinical inputs for second-line (2L) tx and beyond. While addressing those limitations, we examined different clinical scenarios to explore the clinical value of using DARA first vs saving it until a later LOT.

Fonseca: Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy; Janssen: Consultancy; GSK: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; Aduro: Consultancy; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; AbbVie: Consultancy; Mayo Clinic in Arizona: Current Employment; BMS: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Bayer: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Juno: Consultancy; Takeda: Consultancy; Merck: Consultancy. Hashim: Johnson and Johnson: Current Employment. Nair: Janssen Research & Development: Current Employment. He: Janssen: Current Employment, Current equity holder in publicly-traded company. Ammann: Janssen: Current Employment, Current equity holder in publicly-traded company. Lam: Janssen: Current Employment, Current equity holder in publicly-traded company. Wildgust: Janssen: Current Employment, Current equity holder in publicly-traded company. Kumar: Beigene: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Amgen: Consultancy, Research Funding; Antengene: Consultancy, Honoraria; Roche-Genentech: Consultancy, Research Funding; Tenebio: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Consultancy; Bluebird Bio: Consultancy; BMS: Consultancy, Research Funding; Carsgen: Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Research Funding.

Durie: Amgen, Celgene, Johnson & Johnson, and Takeda: Consultancy. Kumar:Takeda: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Usmani:Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau; Amgen Array Biopharma, Bristol-Myers Squibb, Celgene, Janssen, Merck, Pharmacyclics, Sanofi, Takeda: Other: Research Grant; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, SkylineDX, Takeda: Other: Consultant/Advisor. Ammann:Janssen: Employment, Equity Ownership. Lam:Janssen: Employment, Equity Ownership. Kobos:Janssen: Employment. Maiese:Janssen: Employment, Equity Ownership. Facon:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: 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, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees.

Introduction:Daratumumab, a CD38-directed monoclonal antibody, in combination with lenalidomide and dexamethasone (D-Rd), recently received FDA approval for the treatment of patients with newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation (ASCT). FDA approval was based on results of the prespecified interim analysis of a pivotal phase III trial (MAIA) in which D-Rd was compared to Rd among patients with NDMM who were ineligible for ASCT. In the MAIA trial, D-Rd significantly reduced the risk of progression or death compared to Rd. However, no trials have compared D-Rd to other standard-of-care (SOC) regimens. The present study compared progression-free survival (PFS) of D-Rd from the MAIA trial database to common SOC regimens from the Flatiron Health EHR Database, a de-identified nationwide US database of records primarily from community-based oncology practices.

Buxhofer-Ausch: AOP Orphan: Research Funding. Gisslinger:Geron: Consultancy; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; AOP ORPHAN: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Janssen Cilag: Honoraria, Speakers Bureau; Sanofi Aventis: Consultancy. Thaler:AOP Orphan: Research Funding. Schlögl:AOP Orphan: Research Funding. Gastl:AOP Orphan: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Kralovics:AOP Orphan: Research Funding; Qiagen: Membership on an entity's Board of Directors or advisory committees. Ban:AOP Orphan: Research Funding. Egle:AOP Orphan: Research Funding. Melchardt:AOP Orphan: Research Funding. Burgstaller:Celgene: Consultancy, Honoraria, Research Funding; Mundipharma: Honoraria; Novartis: Honoraria; AOP Orphan Pharmaceuticals: Honoraria, Research Funding. Willenbacher:AOP Orphan: Research Funding. Zörer:AOP Orphan: Employment. Ammann-Mwathi:AOP Orphan: Employment. Kadlecova:AOP Orphan: Consultancy. Zagrijtschuk:AOP Orphan: Employment. Klade:AOP Orphan: Employment. Greil:Novartis: Honoraria; Astra-Zeneca: Honoraria; Boehringer-Ingelheim: Honoraria; Sanofi Aventis: Honoraria; GSK: Research Funding; Celgene: Consultancy; Pfizer: Honoraria, Research Funding; Roche, Celgene: Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria; Cephalon: Consultancy, Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Eisai: Honoraria; Mundipharma: Honoraria, Research Funding; Merck: Honoraria; Janssen-Cilag: Honoraria; Genentech: Honoraria, Research Funding; Ratiopharm: Research Funding; AOP Orphan: Research Funding.

Gisslinger: Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; AOP ORPHAN: Consultancy, Honoraria, Research Funding, Speakers Bureau; Geron: Consultancy; Sanofi Aventis: Consultancy; Janssen Cilag: Honoraria, Speakers Bureau. Buxhofer-Ausch:AOP Orphan: Research Funding. Thaler:AOP Orphan: Research Funding. Schlögl:AOP Orphan: Research Funding. Gastl:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AOP Orphan: Research Funding. Ban:AOP Orphan: Research Funding. Egle:AOP Orphan: Research Funding. Melchardt:AOP Orphan: Research Funding. Burgstaller:AOP Orphan Pharmaceuticals: Honoraria, Research Funding; Novartis: Honoraria; Mundipharma: Honoraria; Celgene: Consultancy, Honoraria, Research Funding. Willenbacher:COMET Center ONCOTYROL: Research Funding; AOP Orphan: Research Funding. Kralovics:AOP Orphan: Research Funding; Qiagen: Membership on an entity's Board of Directors or advisory committees. Zörer:AOP Orphan: Employment. Ammann-Mwathi:AOP Orphan: Employment. Kadlecova:AOP Orphan: Consultancy. Zagrijtschuk:AOP Orphan: Employment. Klade:AOP Orphan: Employment. Greil:Pfizer: Honoraria, Research Funding; GSK: Research Funding; Boehringer-Ingelheim: Honoraria; AOP Orphan: Research Funding; Celgene: Consultancy; Janssen-Cilag: Honoraria; Genentech: Honoraria, Research Funding; Novartis: Honoraria; Astra-Zeneca: Honoraria; Amgen: Honoraria, Research Funding; Ratiopharm: Research Funding; Sanofi Aventis: Honoraria; Merck: Honoraria; Mundipharma: Honoraria, Research Funding; Eisai: Honoraria; Cephalon: Consultancy, Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria; Roche, Celgene: Honoraria, Research Funding.

BackgroundRopeginterferon alfa-2b (AOP2014/P1101) is a novel long-acting pegylated IFN-alpha-2b, composed of mainly one isoform, resulting in longer half-life and exposure time. Reduced dosing frequencies, better tolerability, improved compliance and more favorable long-term treatment outcomes in patients with polycythemia vera (PV) are expected. The drug has Orphan designation by EMA and FDA and is currently in the phase III stage of development.

BackgroundRopeginterferon alfa-2b (AOP2014/P1101) is a novel long-acting pegylated IFN-alpha-2b, consisting predominantly of only one isoform, leading to longer half-life and exposure time. Reduced dosing frequencies, better tolerability, improved compliance and more favorable long-term treatment outcomes in patients with polycythemia vera (PV) are expected. The drug has Orphan designation by EMA and FDA and is currently in the phase III stage of development.

Several guidelines on gamma irradiation of blood components state that platelets can be irradiated at any stage in their five-day storage and can thereafter be stored up to their normal shelf life of five days after collection. We explored whether the timing of irradiation has an effect on the transfusion efficacy of APCs.Transfusion efficacy of 809 APCs (median 6/child; range 1-68) transfused to 113 children and adolescents (53 girls and 60 boys, age 0.1y-20.0y) with thrombocytopenia due to a reduced platelet production caused by their haematological/oncological disease itself or by the applied chemotherapy was evaluated retrospectively. Transfusions were divided according to 3 APCs-groups: nonirradiated, irradiated within 24 hours before transfusion (≤ 24h), and irradiated in advance (> 24h). Exclusion criteria were: splenomegaly, fever ≥38.5°C, hemorrhage ≥ WHO Grade 3, or discontinuation of transfusion due to transfusion reactions. Transfusion efficacy was measured by the 1-hour PPR, ( PPR1h [%] = (post-transfusion count [109/L] – pre-transfusion count [109/L]) x blood volume [L] / PLT dose [1011/L]). Accounting for the many patients receiving multiple transfusions, linear mixed regression was used for univariate and multivariate analyses.Univariate comparison of PPR1h is summarized in the table.We recently have shown that a variety of factors influences transfusion efficacy of APCs (TRANSFUSION 48; 2008, p.442; TRANSFUSION 49; 2009, p.21). Therefore, all these variables were included in the present analysis. Multivariate analysis, corrected for storage time, applied apheresis procedure, apheresis yield, ABO transfusion constellation, body weight of recipients, and platelet count before transfusion, confirmed that transfusion of APCs irradiated in advance was associated with a significantly inferior transfusion efficacy compared to nonirradiated APCs (estimated difference in PPR1h, 4.9%; 95% confidence interval, 1.3 to 8.5; p=0.008), while transfusion efficacy of APCs irradiated within 24 hours before transfusion was not (estimated difference in PPR1h, 2.3%; 95% confidence interval, -1.0 to 5.5; p=0.18).Interestingly, no significant difference in transfusion efficacy could be observed between nonirradiated and APCs irradiated within 24 hours before transfusion, while transfusions of platelets irradiated in advance were significantly less efficient. Although many studies, including our own, provide evidence that gamma irradiated platelets have a lower transfusion efficacy, there are no data exploring the impact of the timing of the irradiation. Although our retrospective study indicates a reduced transfusion efficacy of APCs irradiated in advance, only a prospective randomized trial can unequivocally answer the question when platelets should be irradiated.Our data strongly support that irradiation of APCs should be performed at the latest within 24 hours before transfusion. APCs irradiated in advance are less efficient.No relevant conflicts of interest to declare.

Abstract 3139

Background: In contrast to the transfusion of red blood cells there is no evidence for stringent rules on ABO-matching in platelet transfusion. Patients and methods: In a prospective study in pediatric patients we investigated the efficacy of randomly transfused ABO blood group identical and out-of-group (antigen incompatible or antibody [isoagglutinins] incompatible) leukocyte-depleted single donor apheresis platelets (SDP). Four hundred SDP (median, 5/child, range, 1–68) were transfused to 50 children (29 girls and 21 boys, age 0.2 y–18.5 y) with thrombocytopenia due to chemotherapy or aplastic anemia. In the majority, indications for platelet transfusion were not based on platelet counts <5 x 109/L, but were first of all prophylactical; e.g. before lumbar puncture, intramuscular injection, or minor surgery. Exclusion criteria were: splenomegaly, fever ≥38.5°C, major hemorrhage or transfusion reactions. Transfusion efficacy was measured by the 1-hour CCI. (CCI = increase in PLT count [109/L] x body surface area [m2]/number of PLT given [1011]). Expression of A antigen on platelets was assessed by flowcytometry. Accounting for the many patients receiving multiple transfusions, linear mixed effects (LME) analysis was used for univariate and multivariate analyses of the effect of ABO compatibility status on transfusion efficacy. Results: Comparison of data between ABO identical and out-of-group transfusions is summarized in the table. In addition, by multivariate LME the following parameters were significantly and independently associated with CCI: time since apheresis, apheresis device, volume of SDP, irradiation of SDP, and age of the recipients. Discussion: CCI after ABO antigen incompatible transfusions was significantly lower compared to identical transfusions (p=0.018, multivariate analysis), particularly after antigen incompatible transfusion of A1 platelets (p=0.011, multivariate analysis). In patients with blood group O or B, transfused platelets expressing high levels of A antigen were rapidly cleared from the circulation as demonstrated by flowcytometry. Because donors with blood group A2 do not express A antigen on their platelets, after transfusion of A2 SDP there was no difference in CCI as compared to ABO identical transfusions (p=0.76, multivariate analysis). This led to a more striking (p=0.004, multivariate analysis) difference of CCI between ABO identical and antigen incompatible transfusions after excluding A2 SDP from the analysis. Conclusions: If ABO identical SDP are not available, our data strongly support an ABO antigen compatible transfusion strategy for obtaining the best possible CCI - with the only equally effective exception being SDP from A2 donors given to group O or B recipients. However, this would require an extended ABO blood group typing in platelet donors, since by routine typing blood groups A1 and A2 are not differentiated. Although we have not observed significant hemolytic transfusion reactions, ABO antibody incompatible SDP are known to have an inherent risk for it, but relating to CCI they seem to be comparable to ABO identical SDP.

Background: In contrast to the transfusion of red blood cells there is no evidence for stringent rules on ABO-matching in platelet transfusion.

Because of an increasing requirement of single-donor apheresis platelets (SDP) and concomitantly a limited number of platelet (PLT) donors, it is necessary to optimize the productivity of plateletpheresis. One possibility is to increase its yield, targeting 3–4 SDP from one donation. However, no data demonstrate the transfusion effectiveness of these high-yield SDP. In a prospective study in pediatric patients we investigated the effect of plateletpheresis yield on transfusion effectiveness of 225 leukocyte-depleted SDP produced on two different apheresis devices: Amicus Crescendo (Baxter) (n=83), and Trima Accel (Gambro BCT) (n=142). The SDP were transfused to 30 children (17 girls and 13 boys, age up to 18 y) with thrombocytopenia due to chemotherapy or aplastic anemia (median, 7/child, range, 1–52). Exclusion criteria were: splenomegaly, fever, major hemorrhage or transfusion reaction. The transfusion effectiveness, measured by the 1-hour corrected count increment (CCI = increase in PLT count [109/l] x body surface area [m2] / number of PLT given [1011]), was considered as satisfactory if CCI ≥7.5. The median PLT yield was 6.6x1011 (range, 2.6–10.0) with Amicus and 7.9x1011 (1.8–11.5) with Trima. The CCI was ≥ 7.5 in 44/83 (53%) SDP produced with Amicus and in 100/142 (70%) produced with Trima. Results are summarized in the table. Univariate linear mixed effect (LME) analysis revealed that apheresis on the Amicus (p<0.001), need for parenteral calcium application during apheresis (p=0.001), higher PLT concentration in the product (p=0.002), higher apheresis yield (p=0.004), longer delay from apheresis to transfusion (p=0.023), older patient’s age (p<0.001), and a higher number of previous transfusions (p=0.031) were significantly associated with lower CCI. Multivariate LME analysis accounting for the remaining factors demonstrated that a higher apheresis yield led to lower CCI of SDP produced with Amicus (coefficient, −1.93; p=0.037), but not with Trima (−0.06, p=0.90). Looking for explanatory pathophysiological mechanisms, expression of p-selectin on PLTs and pH were measured prospectively in 43 and 22 SDP, respectively. Both lower pH (p=0.024) and higher expression of p-selectin (p=0.001) were significantly associated with lower CCI. High PLT yields showed a tendency for higher p-selectin expression (p=0.084), but no influence on pH (p=0.99).We conclude that at least in the Amicus device higher PLT yields per donation were associated with lower CCI in transfused patients. We recommend that target PLT yield per donation produced with Amicus should not exceed 6.0x1011. At this time, possible explanations for our observations are speculative. In Amicus, PLTs are concentrated in the centrifuge during the whole apheresis, whereas in Trima they are directly collected in the storage bag. PLTs harvested by Amicus are stored in 65% T-sol and 35% donor plasma, whereas PLTs from Trima are stored in undiluted donor plasma. Further studies with different devices are required to measure the effect of plateletpheresis yields on transfusion effectiveness of SDP.

Treatment-related myelodysplastic syndrome (tMDS) is a serious complication of therapy of childhood cancer. Here we report on 59 patients (pts) (35 males, 24 females) with tMDS enrolled in the prospective study EWOG-MDS 98. Prior malignancy was ALL in 21 pts, AML in 5, lymphoma in 6, CNS tumors in 12, and other solid tumors in 15. Median age at diagnosis of tMDS was 11.2 yrs (range 1.2 – 23.2), and median time between first malignancy and tMDS 3.3 yrs (range 0.5 – 11.1). Disease was classified as refractory cytopenia in 15 pts, RAEB in 30 and RAEB-T in 14. Of the 47 pts with cytogenetic analysis at diagnosis, 77% had an abnormal karyotype, including 38% that were complex. Monosomy 7 with or without other abnormalities was detected in 38%. Progression of disease was noted in 26 of 52 evaluable pts at a median time of 2.5 mo (range 0.3 – 16) from diagnosis; the cumulative incidence of progression being 74%. After a median follow-up time of 20 mo (range 3–69) 28 pts are alive with an estimated 5-year overall survival of 32% (95% CI 20 – 51). No child survived beyond 15 mo from diagnosis without receiving allogeneic hematopoietic stem cell transplantation (HSCT). HSCT was performed in 45 pts. Source of stem cells was bone marrow in 24 pts, peripheral blood in 20 and cord blood in 1. The donor was an HLA-identical relative (MFD) in 18 cases, while 26 pts were transplanted from an HLA-matched or 1-antigen/allele disparate unrelated donor (UD) and 1 pt from a 2-antigen disparate parent. Preparative regimen included busulfan 16 mg/kg, cyclophosphamide 120 mg/kg and melphalan 140 mg/m2 in 32 pts. Prophylaxis of GVHD generally consisted of cyclosporine-A for MFD, combined with methotrexate and ALG for UD. Two patients had graft failure. The cumulative incidence of grade II–IV acute GVHD and chronic GVHD were 32% (95% CI 28 – 37) and 24% (95% CI 19 – 28), respectively. Twelve pts suffered transplant-related mortality (TRM), the cumulative incidence of TRM in pts transplanted from a MFD or UD being 12% and 39%, respectively (P=0.058). Prior therapy with platinum compounds was an independent predictor of an increased risk of TRM. Fifteen pts relapsed at a median time of 9 mo (range 2 – 29) after HSCT, the 5-year cumulative incidence of relapse being 44% (95% CI 21 – 66). A WBC > 4 G/L at diagnosis predicted a higher risk of relapse. Twenty-one of the 45 pts transplanted are alive and 19 are disease-free. The estimated 5-year EFS after HSCT was 27% (95% CI 15 – 47). Prior therapy with platinum compounds, a WBC > 4 G/L at diagnosis, and a female donor predicted inferior EFS, while HSCT from an UD versus MFD resulted in similar outcome (5-year EFS, 21% and 39%, respectively). AML-type therapy prior to HSCT did not improve survival. Innovative stragegies for improving the outcome of these patients are warranted.

Treatment-related myelodysplastic syndrome (tMDS) is a serious complication of therapy of childhood cancer. Here we report on 59 patients (pts) (35 males, 24 females) with tMDS enrolled in the prospective study EWOG-MDS 98. Prior malignancy was ALL in 21 pts, AML in 5, lymphoma in 6, CNS tumors in 12, and other solid tumors in 15. Median age at diagnosis of tMDS was 11.2 yrs (range 1.2 – 23.2), and median time between first malignancy and tMDS 3.3 yrs (range 0.5 – 11.1). Disease was classified as refractory cytopenia in 15 pts, RAEB in 30 and RAEB-T in 14. Of the 47 pts with cytogenetic analysis at diagnosis, 77% had an abnormal karyotype, including 38% that were complex. Monosomy 7 with or without other abnormalities was detected in 38%. Progression of disease was noted in 26 of 52 evaluable pts at a median time of 2.5 mo (range 0.3 – 16) from diagnosis; the cumulative incidence of progression being 74%. After a median follow-up time of 20 mo (range 3–69) 28 pts are alive with an estimated 5-year overall survival of 32% (95% CI 20 – 51). No child survived beyond 15 mo from diagnosis without receiving allogeneic hematopoietic stem cell transplantation (HSCT). HSCT was performed in 45 pts. Source of stem cells was bone marrow in 24 pts, peripheral blood in 20 and cord blood in 1. The donor was an HLA-identical relative (MFD) in 18 cases, while 26 pts were transplanted from an HLA-matched or 1-antigen/allele disparate unrelated donor (UD) and 1 pt from a 2-antigen disparate parent. Preparative regimen included busulfan 16 mg/kg, cyclophosphamide 120 mg/kg and melphalan 140 mg/m2in 32 pts. Prophylaxis of GVHD generally consisted of cyclosporine-A for MFD, combined with methotrexate and ALG for UD. Two patients had graft failure. The cumulative incidence of grade II–IV acute GVHD and chronic GVHD were 32% (95% CI 28 – 37) and 24% (95% CI 19 – 28), respectively. Twelve pts suffered transplant-related mortality (TRM), the cumulative incidence of TRM in pts transplanted from a MFD or UD being 12% and 39%, respectively (P=0.058). Prior therapy with platinum compounds was an independent predictor of an increased risk of TRM. Fifteen pts relapsed at a median time of 9 mo (range 2 – 29) after HSCT, the 5-year cumulative incidence of relapse being 44% (95% CI 21 – 66). A WBC > 4 G/L at diagnosis predicted a higher risk of relapse. Twenty-one of the 45 pts transplanted are alive and 19 are disease-free. The estimated 5-year EFS after HSCT was 27% (95% CI 15 – 47). Prior therapy with platinum compounds, a WBC > 4 G/L at diagnosis, and a female donor predicted inferior EFS, while HSCT from an UD versus MFD resulted in similar outcome (5-year EFS, 21% and 39%, respectively). AML-type therapy prior to HSCT did not improve survival. Innovative stragegies for improving the outcome of these patients are warranted.

Because of an increasing requirement of single-donor apheresis platelets (SDP) and concomitantly a limited number of platelet (PLT) donors, it is necessary to optimize the productivity of plateletpheresis. One possibility is to increase its yield, targeting 3–4 SDP from one donation. However, no data demonstrate the transfusion effectiveness of these high-yield SDP. In a prospective study in pediatric patients we investigated the effect of plateletpheresis yield on transfusion effectiveness of 225 leukocyte-depleted SDP produced on two different apheresis devices: Amicus Crescendo (Baxter) (n=83), and Trima Accel (Gambro BCT) (n=142). The SDP were transfused to 30 children (17 girls and 13 boys, age up to 18 y) with thrombocytopenia due to chemotherapy or aplastic anemia (median, 7/child, range, 1–52). Exclusion criteria were: splenomegaly, fever, major hemorrhage or transfusion reaction. The transfusion effectiveness, measured by the 1-hour corrected count increment (CCI = increase in PLT count [109/l] x body surface area [m2] / number of PLT given [1011]), was considered as satisfactory if CCI ≥7.5. The median PLT yield was 6.6x1011(range, 2.6–10.0) with Amicus and 7.9x1011(1.8–11.5) with Trima. The CCI was ≥ 7.5 in 44/83 (53%) SDP produced with Amicus and in 100/142 (70%) produced with Trima. Results are summarized in the table. Univariate linear mixed effect (LME) analysis revealed that apheresis on the Amicus (p<0.001), need for parenteral calcium application during apheresis (p=0.001), higher PLT concentration in the product (p=0.002), higher apheresis yield (p=0.004), longer delay from apheresis to transfusion (p=0.023), older patient's age (p<0.001), and a higher number of previous transfusions (p=0.031) were significantly associated with lower CCI. Multivariate LME analysis accounting for the remaining factors demonstrated that a higher apheresis yield led to lower CCI of SDP produced with Amicus (coefficient, −1.93; p=0.037), but not with Trima (−0.06, p=0.90). Looking for explanatory pathophysiological mechanisms, expression of p-selectin on PLTs and pH were measured prospectively in 43 and 22 SDP, respectively. Both lower pH (p=0.024) and higher expression of p-selectin (p=0.001) were significantly associated with lower CCI. High PLT yields showed a tendency for higher p-selectin expression (p=0.084), but no influence on pH (p=0.99).We conclude that at least in the Amicus device higher PLT yields per donation were associated with lower CCI in transfused patients. We recommend that target PLT yield per donation produced with Amicus should not exceed 6.0x1011.