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Measurable residual disease (MRD) is highly prognostic for relapse and overall survival (OS) in acute lymphoblastic leukemia (ALL), although many patients with apparent “MRD negativity” by standard assays still relapse. We evaluated the clinical impact of a highly sensitive next-generation sequencing (NGS) MRD assay in 74 adults with ALL undergoing frontline therapy. Among remission samples that were MRD negative by multiparameter flow cytometry (MFC), 46% were MRD+ by the NGS assay. After 1 cycle of induction chemotherapy, MRD negativity by MFC at a sensitivity of 1 × 10−4 and NGS at a sensitivity of 1 × 10−6 was achieved in 66% and 23% of patients, respectively. The 5-year cumulative incidence of relapse (CIR) among patients who achieved MRD negativity by MFC at complete remission (CR) was 29%; in contrast, no patients who achieved early MRD negativity by NGS relapsed, and their 5-year OS was 90%. NGS MRD negativity at CR was associated with significantly decreased risk of relapse compared with MRD positivity (5-year CIR, 0% vs 45%, respectively; P = .04). Among patients who were MRD negative by MFC, detection of low levels of MRD by NGS identified patients who still had a significant risk of relapse (5-year CIR, 39%). Early assessment of MRD using a highly sensitive NGS assay adds clinically relevant prognostic information to standard MFC-based approaches and can identify patients with ALL undergoing frontline therapy who have a very low risk of relapse and excellent long-term survival.

Supplement (adjusted per last reviewer comment).

Typical injection schemes of rotating detonation combustors inject fuel locally into the combustion channel, creating stratified fuel-rich and fuel-lean mixing regions. In this study, premixed hydrogen and air rotating detonations are explored in a rotating detonation combustor through premixing part of the fuel into the oxidizer flow. The objective is to investigate the effect of premixing on the operation of the combustor. Three premixing schemes are examined where the detonation wave speeds are analyzed. The results show that in premixing, the fuel-lean regions became more favorable for continuous detonation propagation when premixed with the bypass fuel, resulting in higher detonation wave speeds. This phenomenon is shown to be independent of the global fuel-air equivalence ratio and the amount of fuel premixed into the oxidizer. As such, combustor performance and the operational regime could be improved with lean hydrogen premixing amounts in the main flow oxidizer.

Liquid fuel jet in crossflow (LJIC) is a vital atomization technique significant to the aviation industry. The hydrodynamic instability mechanisms that drive a primary breakup of a transverse jet are investigated using modal and traveling wavelength analysis. This study highlights the primary breakup mechanisms for aviation fuel Jet-A, utilizing a method that could be applied to any liquid fuel. Mathematical decomposition techniques known as POD (proper orthogonal decomposition) and Robust MrDMD (multiresolution dynamic mode decomposition) are used together to identify dominant instability flow dynamics associated with the primary breakup mechanism. Implementation of the Robust MrDMD method deconstructs the nonlinear dynamical systems into multiresolution time-scaled components to capture the intermittent coherent structures. The Robust MrDMD, in conjunction with the POD method, is applied to data points taken across the entire spray breakup regimes: enhanced capillary breakup, bag breakup, multimode breakup, and shear breakup. The dominant frequencies of breakup mechanisms are extracted and identified. These coherent structures are classified with an associated time scale and Strouhal number. Three primary breakup mechanisms, namely, ligament shedding, bag breakup, and shear breakup, were identified and associated with the four breakup regimes outlined above. Further investigation portrays these breakup mechanisms to occur in conjunction with each other in each breakup regime, excluding the low Weber number enhanced capillary breakup regime. Spectral analysis of the Robust MrDMD modes’ entire temporal window reveals that while multiple breakup mechanisms are convolved, there is a dominant breakup route for each breakup regime. An associated particular traveling wavelength analysis further investigates each breakup mechanism. Lastly, this study explores the effects of an increased momentum flux ratio on each breakup mechanism associated with a breakup regime.

This article focuses on extending an H2/air rotating detonation engine's detonability limits by introducing solid carbon particles into the combustor. Carbon black particles consisting of 1% volatility and a carbon concentration of 99% were used as a solid-phase mixing agent for enhanced reaction wave dynamics. Carbon black was found to sustain detonations over multiple operational regimes formerly unattainable without carbon particles. The experiments confirm that detonations were attainable over a wide range of operational parameters, including the total mass flux flowing through the annulus (≅120–270 kg/s m2), the hydrogen/air equivalence ratios (0.65–1.0), and carbon additions (0–20 g). Chemiluminescence imaging was used to visualize the detonation wave within the annulus, quantify detonation wave velocities, and define a detonability map. The detonability map demonstrates the advantage of carbon addition, shows that detonation-based combustion can be sustained at leaner equivalence ratios, reduces hydrogen consumption dependency. The detonation wave velocities decreased as the H2/air equivalence ratio was reduced, where, in general, the detonation wave velocities decreased with respect to the Chapman–Jouguet velocity, suggesting a decrease in the detonation waves efficiency with reduced H2 concentrations. However, an extraordinary phenomenon was witnessed at very lean H2/air equivalence ratios and low mass flux conditions, where the detonation wave velocity increased upward of 100 m/s. This variation is a direct effect of the carbon particles, which drive the detonation wave. Thus, the results demonstrate that carbon particles’ addition provides an economically feasible solution to sustain high-efficiency energy production.

Background: Blockade of PD-1/PD-L1 pathways enhances anti-leukemic responses in pre-clinical studies. PD1 inhibition alone had limited clinical activity in AML. CLTA4 inhibition demonstrated encouraging single-agent CR's in postASCT patients (pts), especially for extra-medullary (EMD) relapses (Davis M et al, NEJM 2016). AZA+Nivo up-regulated CTLA4 on bone marrow (BM) CD8 cells in both responders (R) and non-responders (NR) on treatment (Daver N, et al, Cancer Discovery 2019), suggesting a triplet of AZA+Nivo+Ipi may abrogate PD-1 mediated resistance. Methods: Pts were eligible for the AZA+Nivo (cohort 1, n=59) if they had R/R AML, ECOG ≤ 2, and adequate organ function. This cohort has completed enrollment. A cohort of AZA+Nivo+Ipi was opened (cohort 2), with the same eligibility criteria. Ipi 1mg/kg Q6 weeks was added to the established AZA+Nivo schedule and found to be safe in a lead-in dose cohort. Results: Cohort 1 (59 R/R AML) pts were treated with Aza+Nivo (Daver et al., Cancer Discovery 2019). CR/CRi and OS were superior to contemporary historic HMA-based clinical trial controls at MDACC (Table 1). Pts with low pretherapy BM blasts ( Cohort 2 (36 R/R AML) pts were treated with Aza+Nivo+Ipi, with med age 67 years (25-83), secondary AML (50%), ELN unfavorable cytogenetics (67%), TP53 (36%), med salvage 2 (range, 1-3), and prior HMA based therapies in 67%. All 36 pts are evaluable. Per ELN 2017, CR/CRi was noted in 7 (19%) and PR in 1 (3%). Five (14%) pts had durable stable disease (SD) (defined as absence of CR, CRi, PR; with SD on treatment for ≥6 months), and 23 (64%) were NRs (Table 1). Interestingly, 4 pts with EMD were enrolled and 3 had CR/PR [med DOR 8 (5-13) mos]. The 4- and 8-week mortalities were 0 and 6%, respectively. Grade 3/4 immune toxicities noted in 8 pts (19%), including rash, pneumonitis, colitis, pyrexia. One pt required ICU stay, but no deaths attributed to immune toxicity. Other grade ≥2 toxicities were as expected for R/R AML population and were mostly infections/febrile neutropenia. Converse to AZA+Nivo, on CYTOF, R did not have a higher frequency of pre-therapy BM CD8+ infiltration, but did have progressive BM CD8+ infiltration on therapy, compared with NRs, demonstrating that Ipi (unlike Nivo) may be able to mobilize peripheral T-cells to the BM (Fig 1B). Expansion of a cluster of antigen experienced CD8+ T cells was associated with response (Fig 1B). In all salvage the med OS with Aza+Ipi+Nivo versus Aza+Nivo versus contemporary HMA-controls in R/R AML, were 7.6, 5.9, and 4.6 mos, respectively (P=0.01) (Fig 1C). The 1-year OS in R/R AML pts with AZA+Nivo+Ipi was 25%. The med OS with Aza+Ipi+Nivo was comparable to med OS 6-8 mos reported with HMA+VEN salvage in numerous studies. Conclusion: The OS with Aza+Nivo+Ipi was modestly improved over AZA+Nivo and HMA-controls in R/R AML. Single-cell cytokine profiling and single-cell RNA-seq from Aza+Nivo showed striking pre- and on-treatment differences among R and NR not only in T-cell fitness and clonality, but also in the tumor microenvironment. Ipi may be uniquely able to mobilize peripheral T-cell to BM and EMD. This underappreciated immune diversity suggests a critical need for biomarker-based trials (as we are doing with molecular therapies) for immunotherapies in AML. Disclosures Daver: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Garcia-Manero:Merck: Research Funding; Onconova: Research Funding; Novartis: Research Funding; Jazz Pharmaceuticals: Consultancy; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; H3 Biomedicine: Research Funding; AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Amphivena Therapeutics: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Konopleva:Eli Lilly: Research Funding; Rafael Pharmaceutical: Research Funding; Genentech: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Agios: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Sanofi: Research Funding; Kisoji: Consultancy; Amgen: Consultancy; F. Hoffmann La-Roche: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Ablynx: Research Funding; Forty-Seven: Consultancy, Research Funding. Kadia:Pulmotec: Research Funding; Astellas: Research Funding; Cellenkos: Research Funding; Amgen: Research Funding; Genentech: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Cyclacel: Research Funding; JAZZ: Honoraria, Research Funding; Celgene: Research Funding; Incyte: Research Funding; Astra Zeneca: Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria; Abbvie: Honoraria, Research Funding. DiNardo:AbbVie: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Agios: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Jazz: Honoraria; MedImmune: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Syros: Honoraria; Notable Labs: Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria; Novartis: Consultancy. Borthakur:Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding; PTC Therapeutics: Research Funding; Curio Science LLC: Consultancy; FTC Therapeutics: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; Oncoceutics: Research Funding; Xbiotech USA: Research Funding; Polaris: Research Funding; AstraZeneca: Research Funding; BMS: Research Funding; BioLine Rx: Research Funding; Cyclacel: Research Funding; GSK: Research Funding; Jannsen: Research Funding. Pemmaraju:AbbVie: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Stemline Therapeutics: Honoraria, Research Funding; DAVA Oncology: Honoraria; Incyte Corporation: Honoraria; Celgene: Honoraria; Novartis: Honoraria, Research Funding; SagerStrong Foundation: Other: Grant Support; Plexxikon: Research Funding; LFB Biotechnologies: Honoraria; Blueprint Medicines: Honoraria; Samus Therapeutics: Research Funding; Affymetrix: Other: Grant Support, Research Funding; Pacylex Pharmaceuticals: Consultancy; MustangBio: Honoraria; Roche Diagnostics: Honoraria; Cellectis: Research Funding. Jabbour:Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding. Sasaki:Novartis: Consultancy, Research Funding; Otsuka: Honoraria; Pfizer Japan: Consultancy; Daiichi Sankyo: Consultancy. Yilmaz:Pint Pharma: Honoraria; Pfizer: Research Funding; Daicho Sankyo: Research Funding. Issa:Syndax: Research Funding; Celegene: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Short:AstraZeneca: Consultancy; Amgen: Honoraria; Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding. Andreeff:Amgen: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy. Cortes:Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sun Pharma: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Telios: Research Funding; Astellas: Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Immunogen: Research Funding; Merus: Research Funding. Ravandi:Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Macrogenics: Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Xencor: Consultancy, Honoraria, Research Funding. Allison:BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAB: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Kantarjian:Cyclacel: Research Funding; BMS: Research Funding; Takeda: Honoraria; Agios: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Astex: Research Funding; AbbVie: Honoraria, Research Funding; Jazz Pharma: Research Funding; Amgen: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immunogen: Research Funding; Novartis: Research Funding; Ariad: Research Funding. Sharma:Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Constellation: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAb: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Oncolytics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Infinity Pharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Glympse: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Nivolumab and Ipilimumab based combinations for AML, will be discussed. These agents do not have an on label indication for AML at this time.

Liquid fuel jet in Crossflow (LJIC) is significant to the aviation industry since it is a vital technique for atomization. The hydrodynamic instability mechanisms that drive a transverse jet’s primary breakup were investigated using modal and traveling wavelength analysis. This study highlights the primary breakup mechanisms for aviation fuel Jet-A. However, the techniques discussed are applicable to any liquid. Mathematical decomposition techniques are known as POD (Proper Orthogonal Decomposition), and MrDMD (Multi-Resolution Dynamic Mode Decomposition) are used together to identify dominant instability flow dynamics associated with the primary breakup mechanism. Implementation of the MrDMD method deconstructs the nonlinear dynamical systems into multiresolution time-scaled components that capture the intermittent coherent structures. The MrDMD, in conjunction with the POD method, is applied to data points taken across the entire spray breakup regimes, which are: enhanced capillary breakup, bag breakup, multimode breakup, and shear breakup. The dominant frequencies of both breakup regimes are extracted and identified. These coherent structures are classified with an associated time scale and Strouhal number. Characterization of the traveling column and surface wavelengths are conducted and associated with a known instability model. It is found that the Plateau-Rayleigh instability model predicts columns wavelengths similar to wavelengths found in dominant modes associated with a capillary breakup. Rayleigh Taylor’s instability model matches well with bag and multimode breakup. Small scale surface wavelengths associated with a shear breakup are correlated to a modified Rayleigh Taylor instability model founded by Wang et al. [1]. Furthermore, an atomization model that predicts the Sauter Mean Diameter associated with the dominant small-scale surface traveling wavelengths is established.

Preclinical models have shown that blocking PD-1/PD-L1 pathways enhances antileukemic responses. Azacitidine upregulates PD-1 and IFNγ signaling. We therefore conducted this single-arm trial, in which patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) were treated with azacitidine 75 mg/m2 days 1 to 7 intravenously or subcutaneously with nivolumab 3 mg/kg intravenously on days 1 and 14, every 4 to 6 weeks. For the seventy patients who were treated, the median age was 70 years (range, 22–90) and the median number of prior therapies received was 2 (range, 1–7). The overall response rate (ORR) was 33%, including 15 (22%) complete remission/complete remission with insufficient recovery of counts, 1 partial response, and 7 patients with hematologic improvement maintained >6 months. Six patients (9%) had stable disease >6 months. The ORR was 58% and 22%, in hypomethylating agent (HMA)–naïve (n = 25) and HMA-pretreated (n = 45) patients, respectively. Grade 3 to 4 immune-related adverse events occurred in 8 (11%) patients. Pretherapy bone marrow and peripheral blood CD3 and CD8 were significantly predictive for response on flow cytometry. CTLA4 was significantly upregulated on CD4+ Teff in nonresponders after 2 and 4 doses of nivolumab. Azacitidine and nivolumab therapy produced an encouraging response rate and overall survival in patients with R/R AML, particularly in HMA-naïve and salvage 1 patients. Pretherapy bone marrow aspirate and peripheral blood CD3 percentage may be biomarkers for patient selection. Significance: Azacitidine in combination with nivolumab appeared to be a safe and effective therapy in patients with AML who were salvage 1, prior hypomethylator-naïve, or had increased pretherapy CD3+ bone marrow infiltrate by flow cytometry or IHC. Bone marrow CD3 and CD8 are relatively simple assays that should be incorporated to select patients in future trials. This article is highlighted in the In This Issue feature, p. 305

Background Phenotypic characterization of immune cells in the bone marrow (BM) of patients with acute myeloid leukemia (AML) is lacking. Methods T‐cell infiltration was quantified on BM biopsies from 13 patients with AML, and flow cytometry was performed on BM aspirates (BMAs) from 107 patients with AML who received treatment at The University of Texas MD Anderson Cancer Center. The authors evaluated the expression of inhibitory receptors (programmed cell death protein 1 [PD1], cytotoxic T‐lymphocyte antigen 4 [CTLA4], lymphocyte‐activation gene 3 [LAG3], T‐cell immunoglobulin and mucin‐domain containing‐3 [TIM3]) and stimulatory receptors (glucocorticoid‐induced tumor necrosis factor receptor‐related protein [GITR], OX40, 41BB [a type 2 transmembrane glycoprotein receptor], inducible T‐cell costimulatory [ICOS]) on T‐cell subsets and the expression of their ligands (41BBL, B7‐1, B7‐2, ICOSL, PD‐L1, PD‐L2, and OX40L) on AML blasts. Expression of these markers was correlated with patient age, karyotype, baseline next‐generation sequencing for 28 myeloid‐associated genes (including P53), and DNA methylation proteins (DNA methyltransferase 3α, isocitrate dehydrogenase 1[IDH1], IDH2, Tet methylcytosine dioxygenase 2 [TET2], and Fms‐related tyrosine kinase 3 [FLT3]). Results On histochemistry evaluation, the T‐cell population in BM appeared to be preserved in patients who had AML compared with healthy donors. The proportion of T‐regulatory cells (Tregs) in BMAs was higher in patients with AML than in healthy donors. PD1‐positive/OX40‐positive T cells were more frequent in AML BMAs, and a higher frequency of PD1‐positive/cluster of differentiation 8 (CD8)‐positive T cells coexpressed TIM3 or LAG3. PD1‐positive/CD8‐positive T cells were more frequent in BMAs from patients who had multiply relapsed AML than in BMAs from those who had first relapsed or newly diagnosed AML. Blasts in BMAs from patients who had TP53‐mutated AML were more frequently positive for PD‐L1. Conclusions The preserved T‐cell population, the increased frequency of regulatory T cells, and the expression of targetable immune receptors in AML BMAs suggest a role for T‐cell–harnessing therapies in AML., T‐cell subsets are preserved in the bone marrow of patients with acute myeloid leukemia. The expression of targetable immune checkpoints by T cells suggests that therapies harnessing T cells may benefit these patients.

Coal dust explosions can be hazardous; however, they can also generate a significant rise in stagnation pressure if adequately harnessed. Rotating detonation combustors seek to take advantage of the stagnation pressure rise phenomenon in a more sustained and controlled manner via confinement to a physical annulus, leading to increased overall thermodynamic efficiency. This investigation presents an analysis of detonations fueled by Carbon Black, a solid particulate consisting of virtually pure carbon molecules and lean Hydrogen-Air mixtures. It is realized that with the addition of Carbon Black, an increase of lean mixture detonability and detonation velocities extending the operating limit over that of a pure hydrogen-air mixture is experienced. For all testing conditions, the total equivalence ratio is held at φ = 1, while the fuel mixture's carbon mass fraction is increased from 0 to 0.7 while the hydrogen is decreased. Detonation wave velocities are extracted from high-speed imaging through applying a Discrete Fourier Transform algorithm to determine changes to the wave speed as Carbon Black particles are introduced. As a result, due to the addition of Carbon Black as an auxiliary fuel source, detonations were formed instead of deflagrations in operating conditions where one would expect deflagrations at the same hydrogen-air equivalence ratios without Carbon Black addition. The detonation formation provides evidence that the coal particles are reacting within the detonation wave in a large enough capacity to support a detonation wave within the annulus. Furthermore, the wave speed is shown to increase with the additional of carbon particles. At a constant global equivalence ratio, the detonation wave velocities were found to decrease with hydrogen's incremental replacement with coal particles. Whereby, through a theoretical comparison of the heat of combustion as computed from the experimentally derived detonation wave velocities, a linear relationship of the two was shown to exist. Therefore, the heat of combustion has the potential to describe an operational limit to sustaining a detonation wave.

The present study experimentally investigates adiabatic film cooling effectiveness for high performance flow auxetic geometries (S-Slot and Ellipsoid). Both geometries are auxetic structures that were designed around a Negative Poisson Ratio (NPR). Manufactured NPR combustion liners offer higher quality fracture resistance [1] and high energy absorption [2]. Film cooling effectiveness results for test geometries were non-dimensionalized by a baseline case of circular inline orifices. Non-intrusive pressure sensitive paint (PSP) technique was utilized to obtain local surface pressure gradients for each experimental geometry. Adiabatic film cooling effectiveness measurements were tested for multiple blowing ratios (BR) ranging between 0.05–1.15. Three plate configurations were studied with void inclination angles of 0 degrees. Analyses demonstrate that blowing ratios of 0.5 and 0.75 are optimal for S-slot adiabatic effectiveness. Film cooling results for the Ellipse configuration show increasing effectiveness up to an optimal blowing ratio of 0.5, and decreases as BR is increased beyond that. Additional experiments were performed by keeping the differential pressure across the plates constant. Results indicate that the S-slot provides optimum film cooling effectiveness while the differential pressure conserved in comparison to Ellipses and Circles.

Summary Background Outcomes for younger patients with acute myeloid leukaemia have moderately improved over the past two decades owing to better supportive care and recent introduction of novel targeted agents. Blocking PD-1 and its ligand's pathways enhances antileukaemia responses by enabling T cells in murine models. We aimed to assess the addition of nivolumab to frontline therapy with idarubicin and cytarabine in patients with newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome. Methods This single-arm, phase 2 part of the phase 1–2 study of nivolumab in combination with idarubicin and cytarabine was done at the University of Texas MD Anderson Cancer Center (Houston, TX, USA). Eligible patients were aged 18–60 years (or >60 years if suitable for intensive chemotherapy), and had newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome, and an Eastern Cooperative Oncology Group performance status of 0–2. Induction included cytarabine 1·5 g/m2 by 24-h continuous infusion daily on days 1–4 (3 days in patients >60 years) and idarubicin 12 mg/m2 daily on days 1–3. Nivolumab 3 mg/kg was started on day 24 (range 22–26) and continued every 2 weeks for up to a year in responders. Responders received either up to five consolidation cycles of attenuated doses of idarubicin and cytarabine, or allogeneic stem cell transplantation if eligible. The primary endpoint was event-free survival. Efficacy and safety analyses were done in all patients who received at least one dose of study treatment. Secondary endpoints were relapse-free survival and overall survival. This ongoing trial is registered with ClinicalTrials.gov , number NCT02464657 . Findings Between Aug 7, 2015, and June 2, 2018, 44 patients were enrolled of whom 22 (50%) had adverse genetic risk by European Leukaemia Network classification. All patients were evaluable for safety and efficacy. At a median follow-up of 17·25 months (IQR 0·50–30·40), median event-free survival was not reached (95% CI 7·93–NR). Median relapse-free survival of responders was 18·54 months (95% CI 8·20–23·22). The median overall survival was 18·54 months (95% CI 10·81–28·81). Six patients had seven grade 3–4 immune-related adverse events with two cases of rash, two of colitis, and one each of transaminitis, pancreatitis, and cholecystitis. 19 (43%) of 44 patients achieved a response and proceeded to allogeneic stem cell transplantation, with grade 3–4 graft-versus-host disease observed in five (26%). No treatment related deaths were attributed to nivolumab. Interpretation Addition of nivolumab to induction chemotherapy with idarubicin and cytarabine is feasible in patients with newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome. Post-transplant severe graft-versus-host disease could be improved, and earlier initiation of checkpoint inhibitor therapy is warranted in future studies. Funding The MD Anderson Cancer Center Support Grant CA016672 , and the MD Anderson Cancer Center Leukaemia SPORE CA100632 from the National Cancer Institute, Bristol Myers Squibb.

Background: Preclinically blocking PD-1/PD-L1 pathways enhanced anti-leukemic responses. PD-1 positive CD8 T-cells are increased in the bone marrow (BM) of patients (pts) with relapsed AML (Williams P et al., Cancer 2018). PD1 inhibition alone however had limited clinical activity in AML (Berger et al, Clin Cancer Res 2008). AZA up-regulates PD-1 and PD-L1 in AML and the up-regulation of these genes has been associated with emergence of resistance to AZA (Yang et al., Leukemia 2013). Methods: Pts were eligible for the AZA+Nivo (cohort 1) if they had relapsed/refractory AML (R/R AML), ECOG ≤ 2, and adequate organ function. 70 R/R AML pts were treated. This cohort is closed. A subsequent cohort of AZA+Nivo+Ipi was opened (cohort 2), with the same eligibility criteria. Ipi 1mg/kg Q6 weeks was added to the established AZA+Nivo schedule. This double CPI dosing was based on lung and melanoma dosing. Results: Cohort 1 of 70 R/R AML pts treated with Aza+Nivo (Daver et al., Cancer Discovery 2018). Response rates and OS were superior to contemporary historic HMA-based clinical trial controls at MDACC (Table 1), with most significant OS improvement in patients with low pretherapy BM blasts (10 with a statistically significant OS difference for PSI< vs > 10 (p= 0.0018) (Figure1B), suggesting this may be a more specific biomarker to prospectively select pts for T-cell therapy based trials. RNAseq and nanostring analysis on baseline R vs NR sample will be presented at the meeting. Cohort 2 of 31 R/R AML pts treated with Aza+Nivo+Ipi with median (med) age 71 years (26-86), secondary AML (49%), ELN unfavorable cytogenetics (65%), TP53 (38%), med salvage 2 (range, 1-4). 54% pts previously treated with HMA based therapies. 4 pts had prior alloSCT (med time from alloSCT 13 monts). 24 pts are evaluable, 7 too early. CR/CRi was noted in 9 (36%), additionally 2 (8%) had HI maintained >6 months, 4 (16%) stable disease (SD) (defined as absence of CR, CRi, PR, MLFS; with stable disease on treatment for at least 6 months), and 10 (40%) were NRs. The 4-week and 8-week mortality were 0 and 8%, respectively. In all salvage setting the med OS in Aza+Ipi+Nivo versus Aza+Nivo versus contemporary historical HMA-based clinical trial in R/R AML at MDACC, were 10.5, 6.4, and 4.6 months, respectively (P =0.0025) (Figure 1C). This median OS with Aza+Ipi+Nivo compares favorably even to DAC10+venetoclax in R/R AML (med OS: 7.1 months) reported from our center at ASH 2019. The 1-year OS in R/R AML pts with AZA+Nivo+Ipi was very encouraging at 45%. Grade 3/4 immune mediated toxicities were observed in 6 pts (25%), including rash, pneumonitis, and colitis. One pt required ICU stay but no deaths were attributed to immune toxicity. Other grade >2 toxicities were as expected for R/R AML population and were mostly infections/febrile neutropenia, and electrolyte disturbance. Conclusion: The CR/CRi rates and OS with Aza+Nivo+Ipi are encouraging, with median OS of >10 months in R/R high-risk AML, and the study is enrolling. PSI on pretherapy BM CD4 T-cells from pts treated with Aza+Nivo almost completely segregated Rs vs NRs (p=0.0317). This suggests a very significant and hitherto underappreciated immune diversity in AML and a critical need for biomarker based trials (as we are doing with molecular therapies) with immunotherapies in AML. Disclosures Garcia-Manero: Amphivena: Consultancy, Research Funding; Helsinn: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Celgene: Consultancy, Research Funding; Astex: Consultancy, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Merck: Research Funding. Konopleva:Ablynx: Research Funding; Agios: Research Funding; Astra Zeneca: Research Funding; Reata Pharmaceuticals: Equity Ownership, Patents & Royalties; Kisoji: Consultancy, Honoraria; Ascentage: Research Funding; Genentech: Honoraria, Research Funding; Calithera: Research Funding; F. Hoffman La-Roche: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria; Cellectis: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; Eli Lilly: Research Funding; Forty-Seven: Consultancy, Honoraria. Pemmaraju:incyte: Consultancy, Research Funding; affymetrix: Research Funding; sagerstrong: Research Funding; Daiichi-Sankyo: Research Funding; plexxikon: Research Funding; novartis: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; cellectis: Research Funding; mustangbio: Consultancy, Research Funding; abbvie: Consultancy, Honoraria, Research Funding; celgene: Consultancy, Honoraria; samus: Research Funding. Kadia:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bioline RX: Research Funding; BMS: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. DiNardo:celgene: Consultancy, Honoraria; syros: Honoraria; notable labs: Membership on an entity's Board of Directors or advisory committees; abbvie: Consultancy, Honoraria; agios: Consultancy, Honoraria; jazz: Honoraria; daiichi sankyo: Honoraria; medimmune: Honoraria. Cortes:Biopath Holdings: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; BiolineRx: Consultancy; Sun Pharma: Research Funding; Takeda: Consultancy, Research Funding; Merus: Consultancy, Honoraria, Research Funding; Forma Therapeutics: Consultancy, Honoraria, Research Funding. Ravandi:Macrogenix: Consultancy, Research Funding; Cyclacel LTD: Research Funding; Xencor: Consultancy, Research Funding; Selvita: Research Funding; Menarini Ricerche: Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Jabbour:Amgen: Consultancy, Research Funding; Cyclacel LTD: Research Funding; Pfizer: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding. Takahashi:Symbio Pharmaceuticals: Consultancy. Sasaki:Otsuka: Honoraria; Pfizer: Consultancy. Allison:BMS: Consultancy, Honoraria, Research Funding. Sharma:BMS: Consultancy, Honoraria, Research Funding. Kantarjian:Ariad: Research Funding; Takeda: Honoraria; Jazz Pharma: Research Funding; Agios: Honoraria, Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astex: Research Funding; Cyclacel: Research Funding; BMS: Research Funding; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Amgen: Honoraria, Research Funding; Novartis: Research Funding; AbbVie: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding.

Background The combination of the αPD-1 (nivolumab) and hypomethylating agent azacytidine demonstrated encouraging response rate and overall survival in relapsed/refractory acute myeloid leukemia (AML) patients, compared to azacytidine alone1 (NCT02397720). However, the percentage of the patient who achieved an IWG 2016 response to such therapy was still limited (overall response rate = 33%), so it is desirable to have early predictive biomarkers to facilitate patient stratification and selection for future trials. A better understanding of T cells (primary targets of αPD-1 therapy) from bone marrow (BM) and peripheral blood (PB) in AML pre-therapy and on-therapy should yield valuable insights on the treatment-induced anti-tumor response. Methods We performed whole transcriptomic profiling (RNA-sequencing, RNA-seq) on T cells from a cohort of AML patients who were enrolled in the clinical trial mentioned above, and treated with azacytidine and nivolumab (Table 1). Sixty-four FACS-sorted patient-derived T cell samples from cryopreserved peripheral blood (PB) or bone marrow (BM) aspirates, which were collected pre-therapy (T0) and after the first round of treatment (end of cycle one, EOC1), were evaluated. By leveraging subset definitions based on scRNA-seq results from T cells of cancer patients, we implemented deconvolution of our bulk T-cell RNA-seq data to obtain the relative abundance of different T-cell subsets (in-silico dissection without physical isolation). Results We performed ex vivo cDNA library preparation on 2,000-100,000 sorted T cells and yielded a minimal of 17 million sequencing reads per BM T-cell library and 2.6 million sequencing reads per PBMC T-cell library. We compared the gene expression profile of peripheral blood T cells from AML patients (CD4: n = 16; CD8: n = 15) and healthy donors (HD, n = 8)2,3 to validate our methodology. The deconvolution results were consistent with previously published flow-cytometry data profiling cancer patients4,5 (Figure 1). In comparison with HDs, circulating CD4 T cells from AML patients consisted of a higher frequency of Treg (AML versus HD: 5.1% versus 0.6%, P Independent of the clinical responses attained on the azacytidine and nivolumab, comparison of the pre-therapy CD8 T cells from BM and PB from all AML patients using both gene set enrichment analysis and deconvolution indicated that the BM CD8 T cells were more activated/differentiated compared with PBMC CD8 T cells, likely reflective of an ongoing immune response against the AML. We also found treatment-induced gene expression profile changes in the AML circulating CD8 T cells, characterized by increased cell metabolism and cell proliferation. Deconvolution identified that pre-therapy relative abundance of exhausted (CD3+CD8+PD-1+CD45RO+) and effector (CD3+CD8+CD45RA+Tbet+PD-1lo) CD8 T cells (plasticity) could serve as subpopulations relevant for patient stratification (Figure 2). We further validated these results using CyTOF wherein these same subpopulations were differentially abundant between responders and non-responders at the pre-therapy time-point. Conclusions Collectively, the analyses of RNA-seq of CD8 T cells from AML patients on the azacytidine with nivolumab trial revealed that (1) the PD-1 blockade-based treatment-induced gene expression profiling changes (increased cell proliferation and metabolism) of CD8 T cells are detectable as early as EOC1 in the peripheral blood; (2) specific subpopulations of plastic CD8 T cells identified may have the potential to serve as an actionable biomarker to select AML patients most likely to benefit from such immune checkpoint therapies. These findings need to be confirmed in larger studies, planned or currently being conducted, with αPD-1 based therapies in AML and MDS. References 1. Daver, N. et al.Cancer Discov.9, 370-383 (2019). 2. Corces, M. R. et al.Nat. Genet.48, 1193-1203 (2016). 3. Linsley, P. S. et al. PLoS One9, (2014). 4. Szczepanski, M. J. et al.Clin. Cancer Res.15, 3325-3332 (2009). 5. Knaus, H. A. et al.JCI Insight3, (2018). Disclosures Varadarajan: CellChorus: Employment, Equity Ownership.

7041 Background: Combining PD-1/PD-L1 blockade with hypomethylating agents (HMA) shows encouraging preliminary efficacy in AML, but immune features predictive of response are lacking. Methods: We treated 11 relapsed/refractory (R/R) AML patients with azacitidine (AZA) and nivolumab (Nivo) in a phase 2 clinical trial ( Daver N et al Cancer Discovery 2018). Patient characteristics: median (med) age 65 years (47-73), 63% adverse cytogenetics, 27% TP53 mutated. Pretreatment bone marrow aspirates had immune-phenotypic 17-color flow analysis and NanoString RNA quantification of 1469 immune-relevant genes. Results were correlated with clinical, pathological and molecular data. Results: The median courses of AZA+Nivo administered was 3 (range 1-17). The CR/CRi rate was 45% (including 2 CR, 1 CRi, 1 CRN and 1 CRP), with a median time to response of 1.8 months (range 0.8-4.9 months). The median overall survival was 13 months with 27% patients alive at 1 year. We found significant positive correlations between proportions of T-effector cells at baseline, and CD3+, CD8+, and T-regulatory cells at end of cycle (EOC) 1 (r > 0.75, p < 0.01 for all). At EOC2, these correlations were no longer significant. However, there was a significant positive correlation between T-effector cells at baseline and T-regulatory cells (r = 1, p < 0.001) at EOC4. Using NanoString analysis, we found 105 differentially expressed genes (fold change = 1.5, p < 0.05) between responders (5/11) and non-responders (6/11) at pretreatment. IL2-STAT5, TP53 and TNF Hallmark pathways and immune response from GO gene sets were highly enriched (q < 5x10-4) in responders. We then utilized z-score distribution analysis to quantify the degree of activation of known immunologic pathways. We found that signatures highly specific to neutrophils, NK cells, T-cells and eosinophils were significantly (p < 0.05) upregulated in patients with CR compared to non-responders at pretreatment. Conclusions: Our data demonstrates that a signature suggestive of lymphocyte activation in the pretreatment BM may be associated with augmented clinical response to PD-1 based therapies. Similar underlying pathways that have consistently predicted for responses to PD-1 inhibition in solid cancers, primarily IL2-STAT5 genes, may have predictive relevance in AML. Such pretreatment flow and NanoString signatures may help select AML patients most likely to benefit from PD-1 blockade plus HMA, further enhancing the benefit-risk ratio with such therapies.

Background: Preclinically blocking PD-1/PD-L1 pathways enhanced anti-leukemic responses. PD-1 positive CD8 T-cells were increased in the bone marrow (BM) of pts with AML (Daver et al, ASH 2016). Azacitidine up-regulates PD-1 and interferon-gamma signaling (Yang et al., Leukemia 2013). Methods: Pts were eligible for the AZA+Nivo (cohort 1) if they had relapsed/refractory AML (R/R AML), ECOG ≤ 2, and adequate organ function. The recommended phase 2 dose was established as AZA 75mg/m2 Days 1-7 with Nivo 3mg/kg Day 1 and 14. Courses were repeated approximately every 4-5 weeks indefinitely. 70 R/R AML pts have been treated; cohort 1 is closed. A subsequent cohort of AZA+Nivo+Ipi in R/R AML was opened (cohort 2), with the same eligibility criteria as cohort 1 except that enrollment was restricted to pts with salvage 1 and 2 AML. Ipi 1mg/kg Q6 weeks was added to the established AZA+Nivo schedule. This dosing was based on lung and melanoma dosing for Ipi + Nivo. Responses in both cohorts included best response within 3 months of therapy initiation. Results: Cohort 1: 70 R/R AML pts with median (med) age 70 years (range, 22-90), secondary AML (44%), poor risk cytogenetics (34%), med salvage 2 (range, 1-7) were enrolled. The ORR was 33% including 15 CR/CRi (22%) (4 CR, 11 CRi), 1 PR, and 7 HI maintained on study >6 months (10%) without allogeneic stem cell transplant. Additionally, 6 pts (9%) remained on study with stable disease (SD) >6 months. The remaining 41 pts (58%) had no response. 8-week (wk) mortality was 10%. Patients who achieved a CR/CRi/PR/HI/SD (n=29; 42%) had significantly improved overall survival (OS) compared with NRs (n=41; 58%) (16.1 versus 4.1 months; p Flow-cytometry (MFC) was performed on pre- and post-therapy BMAs, after 2 doses (end of cycle 1 or EOC1) and 4 doses (EOC2) of nivol in 19 of 23 responders (R) (CR/CRi/PR/HI) (83%) and 28 of 41 NRs (68%). 36 parameter CyTOF was performed at same time-points in 5R and 5NRs. On pretherapy BMAs, R had a higher frequency of CD3+ (p=0.04) and CD8+ cells (p=0.09) on MFC (Fig 2A). CD3+ in the pretherapy BMA with a cut-off of 13.2%, had a sensitivity of 74% and a specificity of 65% for predicting response. The CD3+ was >13.2% in 26 of 47 pts (55%) who had an evaluable pretherapy BMA. Immunohistochemistry confirmed that CD3+ cells were increased in pretherapy BMs in R. PhenoGraph clustering of all CD3-gated cells revealed 24 meta-clusters (Fig 2B). The frequency of an effector CD8+ T cell cluster (C2) expressing CD45RA+PD1loTbethiEomeslo was significantly higher in the pretherapy BMAs of R versus NRs (11.2% versus 2.5%; p=0.002), and was further expanded in R not in NRs in the EOC1, EOC2, and EOC4 BMAs (Fig 2C). Cohort 2: 20 pts with R/R AML, med salvage 2 (range 1-2), med age 68 (range, 25-83), secondary AML (36%), adverse cytogenetics (25%), and common molecular mutations TP53 in 5, RAS in 4, DNMT3A/ASXL1 in 2 pts each, were enrolled. 14 pts enrolled before May 1, 2018 were evaluable for response: 6 CR/CRp/CRi (43%) (including 2 CR, 2CRp, 2CRi), 2 stable disease > 6 mths, and 6 no response. The 8-wk mortality was 0. Grade 3/4 irAEs noted in 26% of the pts, most common pneumonitis. Med cycles to response of 2 (1-3). The med OS for all pts was not reached and the projected 1-yr OS in R/R AML was encouraging at 58% (Fig 1). Conclusion: AZA+Nivo was effective in pts with AML in Salvage 1 or those with increased pretherapy CD3+ BM infiltrate by MFC or IHC. BM CD3 and CD8 are simple assays to select pts for future trials of AZA+PD1 inhibitors in AML. AZA+Nivo+Ipi had a encouraging CR/CRp/CRi rate (43%) and med OS (NR) in pts with salvage 1/2 AML and is enrolling. Disclosures Daver: BMS: Research Funding; ImmunoGen: Consultancy; Sunesis: Consultancy; Incyte: Research Funding; Novartis: Consultancy; Karyopharm: Consultancy; Daiichi-Sankyo: Research Funding; Novartis: Research Funding; Pfizer: Consultancy; Karyopharm: Research Funding; Pfizer: Research Funding; Kiromic: Research Funding; ARIAD: Research Funding; Otsuka: Consultancy; Sunesis: Research Funding; Incyte: Consultancy; Alexion: Consultancy. Cortes:novartis: Research Funding. Ravandi:Bristol-Myers Squibb: Research Funding; Astellas Pharmaceuticals: Consultancy, Honoraria; Sunesis: Honoraria; Jazz: Honoraria; Xencor: Research Funding; Bristol-Myers Squibb: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau; Astellas Pharmaceuticals: Consultancy, Honoraria; Xencor: Research Funding; Sunesis: Honoraria; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Macrogenix: Honoraria, Research Funding; Macrogenix: Honoraria, Research Funding; Abbvie: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau. Kadia:Takeda: Consultancy; Abbvie: Consultancy; BMS: Research Funding; BMS: Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Celgene: Research Funding; Pfizer: Consultancy, Research Funding; Celgene: Research Funding; Abbvie: Consultancy; Jazz: Consultancy, Research Funding; Novartis: Consultancy; Takeda: Consultancy; Amgen: Consultancy, Research Funding; Novartis: Consultancy; Jazz: Consultancy, Research Funding. Konopleva:Stemline Therapeutics: Research Funding; Immunogen: Research Funding; abbvie: Research Funding; cellectis: Research Funding. DiNardo:Celgene: Honoraria; Medimmune: Honoraria; Abbvie: Honoraria; Karyopharm: Honoraria; Bayer: Honoraria; Agios: Consultancy. Pemmaraju:daiichi sankyo: Research Funding; SagerStrong Foundation: Research Funding; Affymetrix: Research Funding; novartis: Research Funding; abbvie: Research Funding; stemline: Consultancy, Honoraria, Research Funding; plexxikon: Research Funding; samus: Research Funding; celgene: Consultancy, Honoraria; cellectis: Research Funding.

Background: The combination of an anthracycline and cytarabine has remained a standard of care induction regimen for newly diagnosed AML pts for more than 40 years. PD-1 positive CD8+ T-cells are increased in bone marrow (BM) of AML pts and blocking PD-1/PD-L1 pathways enhances anti-leukemia effect of cytotoxic chemotherapy by increasing CD8+ T-cells in murine models. Addition of Nivo to IA induction may prolong event-free, relapse-free and overall survival (EFS, RFS, OS; respectively). We report on updated feasibility and efficacy data. Methods: Pts aged 18-65 yrs with newly diagnosed AML (≥20% blasts by WHO criteria) and high risk MDS (≥10% blasts) were eligible if they had adequate performance status (ECOG ≤2) and organ function. Treatment included 1-2 induction cycles of (A) 1.5 g/m2 over 24 hours (days 1-4) and (I) 12 mg/m2 (days 1-3). Nivo 3 mg/kg was started on day 24±2 and continued every 2 weeks for up to a yr. For pts achieving complete response (CR) or CR with incomplete count recovery (CRi), up to 5 consolidation cycles of attenuated dose I+A was given. Eligible pts received allogeneic stem cell transplant (alloSCT) at any time during or after consolidation. Results: 3 AML pts were treated at a run-in phase with Nivo 1 mg/kg without drug-related toxicity. Subsequently, 41 pts were treated as above. Median (med) age was 54 yrs (range, 26-66) with 42 AML (32 de novo, 7 secondary, 3 therapy-related) and 2 high risk MDS. 19 pts had adverse ELN genetic risk with 8 TP53 mutations (Fig 1A). All pts were evaluable for response: 34 (77%) achieved CR/CRi (28 CR, 6 CRi) and 18/34 (53%) had undetectable MRD by flow cytometry (FC) following induction. Med number of cycles to response was 1 (range 1-2) and med number of total cycles received was 2 (range, 1-6). Counting maintenance schedule, med number of Nivo doses was 2 (range, 0-25) and 15 pts (34%) received ≥4 doses; 4 pts did not receive Nivo: insurance issues (n=2), early death (n=1) and rapid disease progression (n=1). The 4- and 8-week mortality was 5%. At med follow-up of 17.25 mos (range 0.5-30.4), med OS was 18.54 mos (range, 0.5-30.4) and med RFS for the 34 CR/CRi pts was 18.5 mos (range 1.7-25.6); med EFS was not reached (range 0.5-13.7). When compared to a contemporary cohort of pts treated with I+A alone, there is a trend of improvement of OS at a short follow-up duration (med 18.54 vs 13.2 mos; p=0.2). Six pts had grade 3/4 immune-related toxicities with rash (n=2), colitis (n=2), transaminitis and pancreatitis (n=1; each). Grade 3/4 cholecystitis was possibly attributed to Nivo in 1 pt. 18 (41%) pts proceeded to alloSCT. Donor source was matched related in 3, matched unrelated in 12 and haplo-identical in 3 pts. Conditioning regimen was Fludarabine+busulfan-based in 12, and fludarabine+melphalan in 6 pts. 13 (72%) pts developed graft versus host disease (GVHD)(grades I/II in 8, III/IV in 5), which responded to treatment in 8 (Fig 1B). Multicolor FC studies were conducted on baseline (prior to 1st Nivo dose) and on-treatment BM aspirate and peripheral blood to assess T-cell repertoire and expression of co-stimulatory receptors and ligands on T-cells and leukemic blasts, respectively. Baseline BM was evaluated on 19 responders and 5 non-responders. Pts who achieved CR/CRi had a trend to higher frequency of live CD3+ total T cell infiltrate compared to non-responders in baseline BM aspirates (Fig 1C). We evaluated expression of immune markers on T cell subsets: CD4 T effectors [Teff]: CD3+CD4+CD127lo/+Foxp3-, CD4 T regulatory: CD3+CD4+CD127-Foxp3+, and CD8 T cells. At baseline, BM of non-responders had significantly higher percentage of CD4 Teff co-expressing PD1/TIM3 (p Conclusion: Addition of Nivo to (I+A) induction is feasible and safe in younger AML pts. Post-transplant severe GVHD is not significantly increased and is manageable. CD4+ T-effector cells display exhausted phenotype in non-responders that can be potentially reversed. Studies with earlier initiation of checkpoint inhibitor therapy are planned Figure. Figure. Disclosures Daver: Novartis: Research Funding; ARIAD: Research Funding; Novartis: Consultancy; BMS: Research Funding; Sunesis: Consultancy; Incyte: Research Funding; Karyopharm: Consultancy; Alexion: Consultancy; Daiichi-Sankyo: Research Funding; Kiromic: Research Funding; Pfizer: Consultancy; ImmunoGen: Consultancy; Incyte: Consultancy; Pfizer: Research Funding; Sunesis: Research Funding; Karyopharm: Research Funding; Otsuka: Consultancy. Thompson:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Research Funding; Gilead Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kadia:Amgen: Consultancy, Research Funding; Celgene: Research Funding; BMS: Research Funding; Celgene: Research Funding; Takeda: Consultancy; Abbvie: Consultancy; Novartis: Consultancy; Abbvie: Consultancy; Amgen: Consultancy, Research Funding; BMS: Research Funding; Jazz: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Jazz: Consultancy, Research Funding; Novartis: Consultancy; Takeda: Consultancy; Pfizer: Consultancy, Research Funding. Konopleva:Stemline Therapeutics: Research Funding. DiNardo:Karyopharm: Honoraria; Agios: Consultancy; Bayer: Honoraria; Celgene: Honoraria; Medimmune: Honoraria; Abbvie: Honoraria. Cortes:Pfizer: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Astellas Pharma: Consultancy, Research Funding; Arog: Research Funding. Ravandi:Astellas Pharmaceuticals: Consultancy, Honoraria; Jazz: Honoraria; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Jazz: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Abbvie: Research Funding; Macrogenix: Honoraria, Research Funding; Astellas Pharmaceuticals: Consultancy, Honoraria; Abbvie: Research Funding; Macrogenix: Honoraria, Research Funding; Xencor: Research Funding; Seattle Genetics: Research Funding; Xencor: Research Funding; Sunesis: Honoraria; Sunesis: Honoraria; Orsenix: Honoraria; Orsenix: Honoraria; Seattle Genetics: Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau.

Background: Blocking PD-1/PD-L1 pathways enhances anti-leukemia responses by enabling T-cells in murine models of AML (Zhang et al, Blood 2009). PD-1 positive CD8 T-cells are increased in bone marrow (BM) of pts with AML (Daver et al, AACR 2016). PD1 inhibition has shown activity in AML (Berger et al, Clin Cancer Res 2008). We hypothesized that addition of nivolumab to an induction regimen of ara-C and idarubicin may prolong relapse-free survival (RFS) and overall survival (OS); this study was designed to determine the feasibility of this combination. Methods: Pts with newly diagnosed acute myeloid leukemia (by WHO criteria; ≥20% blasts) and high risk MDS (≥10% blasts) were eligible to participate if they were 18-65 yrs of age and had adequate performance status (ECOG ≤3) and organ function (LVEF ≥ 50%; creatinine ≤ 1.5 g mg/dL, bilirubin ≤ 1.5 mg/dL and transaminases ≤ 2.5 times upper limit of normal). Treatment included 1 or 2 induction cycles of ara-C 1.5 g/m2 over 24 hours (days 1-4) and Idarubicin 12 mg/m2 (days 1-3). Nivolumab 3 mg/kg was started on day 24 ± 2 days and was continued every 2 weeks for up to a year. For pts achieving complete response (CR) or CR with incomplete count recovery (CRi) up to 5 consolidation cycles of attenuated dose ara-C and idarubicin was administered at approximately monthly intervals. Eligible pts received an allogeneic stem cell transplant (alloSCT) at any time during the consolidation or thereafter. Results: 3 pts with relapsed AML were treated at a run-in phase with a dose of nivolumab 1 mg/kg without specific drug-related toxicity. Subsequently, 32 pts (median age 53 yrs; range, 26-65) were treated as above including 30 with AML (24 de novo AML, 2 therapy-related AML, 3 secondary AML and 1 therapy-related secondary AML) and 2 high risk MDS. Pre-treatment genetic risk by ELN criteria was 11 adverse, 16 intermediate, and 5 favorable, including 2 FLT3 -ITD mutated, 5 NPM1 mutated, and 7 TP53 mutated. All 32 pts were evaluable for response and 23 (72%) achieved CR/CRi (19 CR, 4 CRi). The 4-week and 8 week mortality was 6% and 6%. The median number of doses of nivolumab received was 6 (range, 0-13); one pt did not receive nivolumab due to insurance issues. 9 pts underwent an alloSCT. After a median follow-up of 8.3 mths (range, 1.5-17.0) the median RFS among the responding pts has not been reached (range, 0.1 - 15.8 mths) and the median OS has not been reached (range 0.5-17.0 mths). Grade 3/4 immune mediated toxicities have been observed in 5 pts and include rash, pancreatitis, and colitis. Other grade 3/4 toxicities thought to be potentially related to nivolumab include cholecystitis in one pt. 9 pts proceeded to an alloSCT. Donor source was matched related in 2, matched unrelated in 6 and haplo-identical in 1 pt. Conditioning regimen was Fludarabine plus busulfan-based in 8, and fludarabine plus melphalan in 1 pt. 4 pts developed graft versus host disease (GVHD)(grade I/II in 3, grade III/IV in 1), which responded to treatment in 3. Multicolor flow-cytometry studies are conducted by the Immunotherapy Platform on baseline (prior to first dose of nivolumab) and on-treatment BM aspirate and peripheral blood to assess the T-cell repertoire and expression of co-stimulatory receptors and ligands on T-cell subsets and leukemic blasts, respectively. The baseline BM was evaluated on 23 of the 32 evaluable pts, including 18 responders and 5 non-responders. Pts who achieved a CR/CRi had a trend of higher frequency of live CD3+ total T cell infiltrate as compared to non-responders in the baseline BM aspirates (Fig 1A). We evaluated expression of immune markers on T cell subsets: CD4 T effector cells [Teff]: CD3+CD4+CD127lo/+Foxp3-, CD4 T regulatory cells [Treg]: CD3+CD4+CD127-Foxp3+, and CD8 T cells. At baseline, BM of non-responders had significantly higher percentage of CD4 T effector cells co-expressing the inhibitory markers PD1 and TIM3 (p Conclusion: Addition of nivolumab to ara-C and anthracycline induction chemotherapy is feasible and safe in younger pts with AML. Among the pts proceeding to alloSCT the risk of GVHD is not significantly increased. Figure 1 Figure 1. Disclosures Daver: Pfizer Inc.: Consultancy, Research Funding; Otsuka America Pharmaceutical, Inc.: Consultancy; Sunesis Pharmaceuticals, Inc.: Consultancy, Research Funding; Novartis Pharmaceuticals Corporation: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; Kiromic: Research Funding; Karyopharm: Consultancy, Research Funding; Jazz: Consultancy; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Incyte Corporation: Honoraria, Research Funding. Thompson: Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees. Jabbour: Bristol-Myers Squibb: Consultancy. Takahashi: Symbio Pharmaceuticals: Consultancy. DiNardo: Novartis: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Sharma: Jounce: Consultancy, Other: stock, Patents & Royalties: Patent licensed to Jounce; Astellas: Consultancy; EMD Serono: Consultancy; Amgen: Consultancy; Astra Zeneca: Consultancy; GSK: Consultancy; Consetellation: Other: stock; Evelo: Consultancy, Other: stock; Neon: Consultancy, Other: stock; Kite Pharma: Consultancy, Other: stock; BMS: Consultancy. Cortes: BMS: Consultancy, Research Funding; Sun Pharma: Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Teva: Research Funding; ImmunoGen: Consultancy, Research Funding; ARIAD: Consultancy, Research Funding. Kantarjian: Delta-Fly Pharma: Research Funding; Amgen: Research Funding; ARIAD: Research Funding; Novartis: Research Funding; Bristol-Meyers Squibb: Research Funding; Pfizer: Research Funding.

Introduction Herein we present details of the standard procedures and operations of the Leukemia Sample Bank (LSB) as a guide to others desiring to establish their own bank. The availability of primary tissue samples to evaluate the molecular biology and pathogenesis of leukemia, as well as to develop and evaluate novel therapeutic strategies, has been instrumental to advances in the leukemia field. The Department of Leukemia at the University of Texas M. D. Anderson Cancer Center (MDACC) improves the treatment of patients with leukemias by providing basic, translational, and clinical scientists access to clinically annotated fresh and frozen primary tissue samples to test and validate their hypotheses. The LSB was created to collect, process, and maintain tissue specimens from patients with known or suspected hematologic malignancies, and also maintains a comprehensive, prospective, interactive database with detailed clinical and pathologic data and facilitates distribution of samples to various investigators. Bank Design and Activity An MDACC protocol was IRB approved in 2001 to facilitate primary leukemia tissue collection, storage, and distribution. The protocol serves as a "front door" consent to the Leukemia Department for approaching all new patients that come to the Leukemia Center. The protocol allows for use of tissue samples for current and future research projects related to researching hematological malignancies. Investigators utilize a separate IRB approved "back door" protocol, with a waiver of consent, to obtain samples for various projects. The LSB protocol thus serves as a single-sign research consent for patients, avoiding consent "fatigue" and ennui. A bank usage committee reviews request for samples and determines which to approve, including collaborations that are intra departmental, intra institution, inter academic institutional and with pharmaceutical institutions. A priority of usage is given to MDACC leukemia department investigators, other academic departments inside and outside MDACC, and finally to pharmaceutical institutions. Our policy is not to release the last vial of material for any particular patient. In the past year, these efforts have resulted in 93% of patients being approached, 82% providing consent, and only 11% declining. While most patients are motivated to consent to help advance research and improve treatments, hematology banks are unique in that they experience barriers to consent that solid tissue banks may not. Once blood and bone marrow samples are obtained, samples are processed per disease specific algorithms on the same day of collection to yield disease enriched material such as DNA, RNA, protein, serum or viable cells. Same day processing removes cryopreservation effects on labile analytes (mRNA, miRNA, protein) that could arise from a freeze thaw cycle. Material is distributed fresh to investigators or cryopreserved for later use. Samples are collected serially at the time of diagnosis, during therapy, in remission, or at relapse. The LSB provides annotated clinical data for any distributed samples. In support of the bank, a database records sample collection and archive details, and provides "chain of custody". A query tool was also developed allows for searching sample inventory by demographic, clinical, and sample characteristics, which also links to the Leukemia Clinical Data Repository (LCDR), to allow for searching of samples by leukemia specific characteristics such as diagnosis, prior treatments, and cytogenetic abnormalities. Results The LSB is one of the world's largest leukemia repositories and serves as a valuable local and national resource. The very high levels of patients consenting to participate make the holdings truly representative of all leukemias. The serial samples collected from patients allow for comparison between diagnosis and relapse states of disease. The ability to provide detailed annotation of clinical, laboratory, and outcome data further increases the value of research done with these samples. The LSB continues to collect valuable samples for use in research related to improving patient outcomes for patients with hematological malignancies. Disclosures No relevant conflicts of interest to declare.

Background: Limited data is available on expression levels of checkpoint receptors, respective ligands, and other immune markers in patients with CLL (Ramsay et al. Blood 2012). Checkpoint blockade has been a successful therapy of many cancers including melanoma, and more recently, Hodgkin's lymphoma. Understanding expression patterns of checkpoint receptors and ligands may help in the clinical development of checkpoint blockade as a therapy for patients with CLL. Methods: Between September 2015 and April 2016, we performed 17-color multi-parameter flow-cytometry (MFC) in paired peripheral blood (PB) and bone marrow (BM) samples from 30 patients with CLL who presented as new patients for evaluation at MDACC. Patients may have received prior CLL therapy. We evaluated expression of immune receptors (inhibitory receptors: PD1, CTLA4, LAG3, TIM3; activating receptors: GITR, OX40, 41BB, ICOS) on T cell subsets: CD4 T effector cells [Teff]: CD3+CD4+CD127lo/+Foxp3-, CD4 T regulatory cells [Treg]: CD3+CD4+CD127-Foxp3+, and CD8 T cells. CLL cells were assessed for both immune receptors (as above), and ligands (4-1BBL, B7-1, B7-2, ICOSL, PDL-1, PDL-2, OX40L). These analyses were performed on freshly collected PB and BM samples by the M. D. Anderson Cancer Center Immunotherapy Platform. Results: A total of 30 patients with CLL were enrolled. The median age was 66 years (range, 35-83). Nine were women. Nineteen were treatment-naive. Prognostic markers included FISH [del(17p) = 6; del(13q) = 9, del(11q) = 4, trisomy 12 = 3, negative = 8]. IGHV mutation status was available for 19 patients (13 unmutated IGHV, 6 mutated IGHV). B2M was ≥3.5 in 11 pts. Baseline expression of costimulatory receptors in CD8 T cells in the marrow, and of the ligands in CLL cells in the marrow is shown in Figure 1. In paired PB and BM sample analysis, there was a high correlation between expression level of PD1 on Treg (Pearson correlation, r = 0.90, p Patients with prior therapy had significantly higher expression of PDL1 on the CLL cells in both PB and BM (p=0.01 and p=0.002, respectively) compared to previously untreated patients. OX40 expression on CD8 cells was significantly higher in both PB and BM in previously treated patients (compared to previously untreated patients). Patients with unmutated IGHV (p = 0.003) and del17p (p = .03) had higher PDL1 expression on CLL cells in the marrow. Conclusions: There is a strong correlation in the expression levels of PD1 on various T cell subsets between PB and BM. Clinically targetable checkpoint receptors including PD1, OX40, CTLA4, and ICOS are consistently expressed across patients with CLL, and present on cells in both PB and BM. Disclosures Jain: BMS: Research Funding; Abbvie: Research Funding; ADC Therapeutics: Consultancy, Honoraria, Research Funding; Novimmune: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Genentech: Research Funding; Infinity: Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Novartis: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Seattle Genetics: Research Funding; Celgene: Research Funding. Burger:Roche: Other: Travel, Accommodations, Expenses; Pharmacyclics, LLC, an AbbVie Company: Research Funding; Janssen: Consultancy, Other: Travel, Accommodations, Expenses; Portola: Consultancy; Gilead: Research Funding. Thompson:Pharmacyclics: Consultancy, Honoraria. Daver:Otsuka: Consultancy, Honoraria; Ariad: Research Funding; Karyopharm: Honoraria, Research Funding; BMS: Research Funding; Sunesis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Kiromic: Research Funding. Wierda:Acerta: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Novartis: Research Funding; Abbvie: Research Funding.

Introduction: The expression of co-stimulatory (costim) receptors/ligands in the bone marrow (BM) and peripheral blood (PB) in patients (pts) with AML has not been defined. Identification of immune-checkpoint pathways that dominate in AML will guide the rational selection of specific antibodies for clinical trials. Methods: Between March, 2015 and October 2015 we performed 17-color multi-parameter flow-cytometry (MFC) on 15 untreated AML and 25 relapsed AML to assess expression of costim ligands (4-1BBL, B7-1, B7-2, ICOSL, PDL-1, PDL-2, OX40L) on leukemic blasts and costim receptors (4-1BB, CTLA-4, ICOS, PD-1, OX40, GITR, LAG-3, TIM-3) on T cell subsets: CD4 T effector cells [Teff]: CD3+CD4+CD127lo/+Foxp3−, CD4 T regulatory cells [Treg]: CD3+CD4+CD127−Foxp3+, and CD8 T cells: CD3+CD8+. Four healthy human BMs were used as control. Expression is denoted by percentage of specific T-cell subset or gated AML blasts positive for the marker indicated. PB mononuclear cells (PBMCs) and blasts were evaluated at the same time-point. Results: OX40+ Teffs and OX40+ CD8 cells were higher in untreated AML BM as compared to healthy donor BM (median [med]: 7.2% versus [vs] 0.26%; P = 0.0005 and med: 2.03% vs 0.06%; P = 0.07, respectively). PD1+ Tregs and OX40+ Tregs were also higher in untreated AML BM as compared to healthy donor BM (med: 19.7% vs 7.5%; P = 0.03 and med: 10.3% vs 0.5%; P = 0.02, respectively). PD1+ Teffs, OX40+ Teffs, and ICOS+ Teffs were higher in relapsed AML BM as compared to healthy donor BM (med: 17.7% vs 6.7%; P = 0.047, med: 12% vs 0.27%, P = 0.002, and med: 13.3% vs 1.1%; P = 0.07, respectively). OX40+ CD8 cells, ICOS+ CD8 cells, TIM3+ CD8 cells (med: 5.0% vs 0.07%; P = 0.04, med: 18.5% vs 2.6%; P = 0.09, and med: 2.7% vs 0.7%; P = 0.01, respectively) and OX40+ Tregs (med: 15.5% vs 0.5%; P Conclusions: Clinically targetable checkpoint receptors including PD1, OX40, and ICOS appear to be overexpressed in the BM of pts with AML as compared to healthy donor BM. Relapsed AML had higher expression of costim receptors than untreated AML. Three anti-PD1 based clinical trials for pts with AML are enrolling at our institution (NCT02397720, NCT02464657, NCT02532231). Citation Format: Naval Daver, Sreyashi Basu, Guillermo Garcia-Manero, Jorge Cortes, Farhad Ravandi, Steven Kornblau, Marina Konopleva, Michael Andreeff, Gautam Borthakur, Nitin Jain, William Wierda, Srdan Verstovsek, Peter Ruvolo, Tapan Kadia, Jairo Matthews, Wilmer Flores, Hui Yang, Carlos Bueso-Ramos, Narmeen Somani, Jorge Blando, James Allison, Hagop Kantarjian, Padmanee Sharma. Defining the immune checkpoint landscape of acute myeloid leukemia (AML). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3205.

The Platanares geothermal area, Departamento de Copan, Honduras, is located within a graben that is complexly faulted. The graben is bounded on the north by a highland composed of Paleozoic (?) metamorphic rocks in contact with Cretaceous - Tertiary redbeds of unknown thickness. These are unconformably overlain by Tertiary andesitic lavas, rhyolitic ignimbrites, and associated sedimentary rocks. The volcanic rocks are mostly older than 14 Ma, and thus are too old to represent the surface expression of an active crustal magma body. Thermal fluids that discharge in the area are heated during deep circulation of meteoric water along faults in a region of somewhat elevated heat flow. Geothermometry based upon the chemical composition of thermal fluids from hot springs and from geothermal gradient coreholes suggests that the reservoir equilibrated at temperatures as high as 225 to 240°C, within the Cretaceous redbed sequence. Three continuously cored geothermal gradient holes have been drilled; fluids of about 165°C have been produced from two drilled along a NW-trending fault zone, from depths of 250 to 680 m. A conductive thermal gradient of 139°C/km, at a depth of 400 m, was determined from the third well, drilled 0.6 km west of that fault zone. These data indicate that the Platanares geothermal area holds considerable promise for electrical generation by moderate- to hightemperature geothermal fluids.

Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ≥ 1.5 km in a region of active tectonism devoid of Quaternary volcanism. Large, artesian water entries of 160 to 165°C geothermal fluid in two core holes at 625 to 644 m and 460 to 635 m depth have maximum flow rates of roughly 355 and 560 l/min, respectively, which are equivalent to power outputs of about 3.1 and 5.1 MW(thermal). Dilute, alkali-chloride reservoir fluids (TDS ≤ 1200 mg/kg) are produced from fractured Miocene andesite and Cretaceous to Eocene redbeds that are hydrothermally altered. Fracture permeabillity in producing horizons is locally greater than 1500 and bulk porosity is ≤ 6%. A simple, fracture-dominated, volume-impedance model assuming turbulent flow indicates that the calculated reservoir storage capacity of each flowing hole is approximately 9.7 × 106 l/(kg cm−2), Tritium data indicate a mean residence time of 450 yr for water in the reservoir. Multiplying the natural fluid discharge rate by the mean residence time gives an estimated water volume of the Platanares system of ≥ 0.78 km3. Downward continuation of a 139°C/km “conductive” gradient at a depth of 400 m in a third core hole implies that the depth to a 225°C source reservoir (predicted from chemical geothermometers) is at least 1.5 km. Uranium-thorium disequilibrium ages on calcite veins at the surface and in the core holes indicate that the present Platanares hydrothermal system has been active for the last 0.25 m.y.

The Platanares geothermal system is located in a region of active Quaternary tectonism in western Honduras. Although the geothermal area is partially blanketed by Miocene ignimbrites (14.5 m.y.), there are no nearby Quaternary volcanic rocks to suggest a young, subsurface, magmatic heat source. No acid-sulfate waters, indicative of vapor-dominated conditions, exist in the area. Hot spring activity is most vigorous along a 2 km stretch of the Quebrada del Agua Caliente fault zone. Natural discharge is high (33001/min), spring temperatures range from 35 to 100°C, pH ranges from 7 to 9, and total dissolved solids are low (1100 mg/kg). Chemical geothermometers indicate a subsurface reservoir temperature of about 225°C. Three exploration core holes (7.8 cm diameter) have been drilled to a maximum depth of 680 m and maximum temperature of 165°C. Two holes produce copious amounts of water under artesian conditions (5001/min maximum; 5 bars flowing) from fractured red beds of Cretaceous to Eocene age (Valle de Angeles Group). Maximum power output is 4.5 MW (thermal) but CO2 released during flashing formed some aragonite scale in one hole. The third core hole has an apparent conductive gradient of 139°C/km at400m. Downward continuation of this gradient implies that the minimum depth to a possible geothermal resource (225°C) is about 1.5 km.

From 1985 to 1987, the National Company of Electrical Energy developed simultaneously two evaluation projects of geothermal resources in Honduras. One of these was with the assistance of the U.S. Agency for International Development and the other of the United Nations Development Program; the first project rapidly evaluated geothermal areas previously identified, then concentrated on the Platanares area; the second evaluated the central region of Honduras, undertaking detailed work in the Azacualpa and San Ignacio areas as well as in the Comayagua and Sula grabens.