Al Plasma Research Articles

Transmissions of an x-ray free electron laser pulse through Al: Influence of nonequilibrium electron kinetics.

A theoretical model for investigating the radiative transfer of an x-ray free electron laser (XFEL) pulse is developed based on a one-dimensional radiative transfer equation. The population dynamics of energy levels is obtained by rate equationapproximation coupling with the Fokker-Planck equation, in which the electron energy distribution function (EEDF) is self-consistently determined. As an illustrative example, XFEL pulse propagation through a solid-density aluminum (Al) is investigated. The characteristics of the temporal evolution of the x-ray pulse shape, level population, and EEDF are demonstrated. The EEDF usually has two parts in XFEL-Al interactions: the near equilibrium part in the lower energy regions and the nonequilibrium part in the higher energy region. The deep gap between the two parts is quickly filled in the solid-density Al plasma. The pulse shape is distorted and the duration shortens as the x-ray pulse propagates through the Al sample. The x-ray transmission spectra were compared with experimental and other theoretical results, and good agreement was found. There are slight discrepancies between the transmission obtained by solving the Fokker-Planck equationand Maxwellian assumptions because nonequilibrium electrons in the higher energy region account for only a small fraction of the total electrons.

Spectral Analysis of Al Arc Discharge Plasma Generated in ZnO/DDDW Colloid

This study aims to investigate the aluminum (Al) arc plasma parameters generated through the explosive strip technique. The research involves the measurement of key plasma characteristics such as plasma frequency (fp), Debye length, and Debye number. The electron temperature (Te) and electron density (ne) of the plasma were calculated utilizing the Boltzmann plot and Stark expansion method. Analysis of the optical emission spectrum revealed distinctive peaks corresponding to oxygen, Al, and zinc oxide (ZnO) within the plasma. The outcomes of the study demonstrated a noteworthy correlation between the applied current and the electron temperature and density. Specifically, as the current increases, both electron temperature and density increase. The electron temperature of the Al plasma increased from the range of 0.852 eV to 0.92404 eV, accompanied by a corresponding elevation in electron density from 13.1× 1017 cm-3 to 15.2× 1017 cm-3. Furthermore, the detonation of the Al strip within a ZnO suspension led to even more pronounced changes. In this case, the electron temperature surged from 0.92885 eV to 1.1012 eV, and the electron density experienced an increase from 37.7 × 1017 cm-3 to 44.7 × 1017 cm-3.

Effect of Sample Temperature on Spectra of AlO Molecules in Femtosecond Laser-Induced Al Plasma

Effect of Sample Temperature on Spectra of AlO Molecules in Femtosecond Laser-Induced Al Plasma

Study on the propagation properties of terahertz waves in spacecraft dusty plasma sheath

Terahertz (THz) wave transmission in non-uniform dielectric layer containing dusty plasmas and aluminum (Al) is investigated by using the Wentzel–Kramer–Brillouin method. The application of magnetic field and increase in electromagnetic waves frequency are up-and-coming solutions for the “blackout” issue. Therefore, this work considers the effect of external magnetic field and electron density distribution. The electron density distributions are assumed to be double Gaussian profile, uniform distribution, Epstein distribution, and both right- and left-hand circularly polarized waves are analyzed. Then the effects of physical parameters and THz frequency on the transmission properties are analyzed. Results show that the presence of Al can shield electromagnetic waves, but we can still control THz waves in lower frequency band to achieve communication. By adjusting THz waves frequency and plasma parameters, waves can pass through the Al plasma sheath effectively under certain circumstances. It is expected to mitigate the blackout issue of hypersonic spacecraft.

Four-framed X-ray imaging crystal spectrometer for time-resolved laser plasma diagnostics

X-ray imaging crystal spectrometers with high spectral and spatial resolutions are the important diagnostic tools for acquiring high-quality plasma information in the study of laser–matter interactions. In this paper we propose a new multi-channel imaging crystal spectrometer with coupling X-ray framing camera to record the dynamic evolution of a laser-induced plasma: a four-channel imaging mica crystal spectrometer with a spatial resolution of 40–60 μm for diagnosing the aluminum (Al) plasma targets was developed. Calibration experiments revealed that the spectral resolution is higher than 1700 at Al Kα3 characteristic lines (1496.4eV). Further, we established an aiming method based on the positioning ball and two monitoring CCDs. The optical design, mechanical design, and experimental measurements of the four-channel imaging mica crystal spectrometer are discussed.

Effect of Al2O3 and MoS2 reinforcement on microstructure, mechanical, and wear properties of plasma sprayed aluminium hybrid composite coating

This study investigates the role of incorporating alumina (Al2O3) and molybdenum disulfide (MoS2) into an aluminium (Al) plasma sprayed coating on microstructure, mechanical, and wear properties. For this, we fabricated four different coatings with various compositions viz. Al,Al + 10 wt% Al2O3, Al+ 5 wt% MoS2, Al+ 10 wt% Al2O3 + 5 wt% MoS2 utilizing a plasma spraying. The microstructure analysis reveals that the reinforcements are distributed uniformly within the coating, and relative density of Al hybrid composite coating has enhanced significantly to 97.5%. Furthermore, mechanical properties like hardness and elastic modulus increased to 112.5% and 77.1%, respectively. Then, reinforcement of Al2O3 and MoS2 into the Al coating significantly reduces the wear rate and coefficient of friction of the coating as 45.5% and 72.3% respectively. These improved tribological properties of the coating can be accredited to the enhanced hardness and lubrication characteristics of the reinforcements. The findings suggest that incorporating both Al2O3 and MoS2 into an Al plasma sprayed coating can be a promising approach for improving the coating's microstructural, mechanical, and tribological properties, making it suitable for a variety of industrial applications.

Collimation and energy enhancement in laser driven MeV protons

Enhancing the energy and controlling the divergence of proton beam have been crucial tasks since the development of laser-based ion accelerators. In this study, we employ 2D particle-in-cell EPOCH simulation to investigate a method to control the divergence and enhance the energy of MeV proton beam produced from the interaction of high intensity laser with a gold target. The energy and divergence of proton beam for the conventional laser-foil target configuration are compared with our proposed three laser-three target configuration. In the single laser-single target configuration, a high intensity laser irradiates a gold foil target resulting in proton acceleration from the plasma. In contrast, in the three laser-three target configuration, the generated proton beam is allowed to traverse through the configuration of two parallel Al plates irradiated with high intensity lasers. The new configuration provides the proton energy enhancements of 40% and more collimated beam compared to the single laser-foil target setup. This collimation and energy increase are due to the vertical and horizontal components of the electric field generated by the hot electron plasma of Al plates. The proton energy and divergence can also be tuned by varying the plasma electron density of the Al plasma. Also, the control of proton beam collimation is explored by varying target parameters as well, and it is observed that the separation between the Al plates and length of the Al plates plays major role in controlling the divergence of the beam. This study will have a significant impact in the ongoing laser fusion program, fast ignition, and laser ion therapy.

Real optical imaging simulation of laser-produced aluminum plasmas.

We developed a post-processing optical imaging model based on two-dimensional axisymmetric radiation hydrodynamics. Simulation and program benchmarks were performed using laser-produced Al plasma optical images obtained via transient imaging. The emission profiles of a laser-produced Al plasma plume in air at atmospheric pressure were reproduced, and the influence of plasma state parameters on radiation characteristics were clarified. In this model, the radiation transport equation is solved on the real optical path, which is mainly used to study the radiation of luminescent particles during plasma expansion. The model outputs consist of the electron temperature, particle density, charge distribution, absorption coefficient, and corresponding spatio-temporal evolution of the optical radiation profile. The model helps with understanding element detection and quantitative analysis of laser-induced breakdown spectroscopy.

Experimental setup for interaction between highly charged ions and laser-produced plasma near Bohr velocity energy region

Ion energy loss in the interaction between highly charged ions and dense plasma near Bohr velocity energy region is one of the important physical problems in the field of high-energy density physics driven by intense heavy ion beams. Based on the 320 kV experimental platform at the Institute of Modern Physics, Chinese Academy of Sciences, a new experimental setup was built for the research of interaction between ions and laser-produced plasma near the Bohr velocity, where the ion energy loss and charge state distribution can be experimentally investigated. In this paper we introduce the new setup in detail, including the generation and controlling of pulsed ion beam ( ≥ 200 ns); the preparation of high-density laser plasma target (10<sup>17</sup>—10<sup>21</sup> cm<sup>–3</sup>); the diagnostics of plasma and the developed high energy resolution ion measurement system (< 1%). In the experiment, the charge distribution of Xe<sup>15+</sup> ions with 4 MeV penetrating through the laser-produced Al plasma target is measured. The charge-state analysis device observes different results without and with the plasma, in which the outgoing Xe ion charge-state changes correspondingly from the 15+ to 10+, thus the electron capture process is believed to be dominant. In addition, the proton energy loss is also measured by using the magnetic spectrometer, showing that the experimental energy loss is about 2.0 keV, 30% higher than those theoretical predictions , which can be attributed to the fact that in the near Bohr velocity energy regime, the first-order Born approximation condition is not valid, thus the Bethe model and SSM model are inapplicable to the experimental results. In future, a systematic study will be performed based on our ions-plasma ineteraction setup, and the energy loss and charge state data will be introduced.

X-ray spectroscopy of laser produced Al plasma near the target surface in a laser ion source

The spatially resolved x-ray spectrum of a laser produced Al plasma near the target surface has been obtained in the energy range of 1.5–2.2 keV using a compact flat crystal spectrometer. The widely used temperature and density diagnostics, the line ratios of Lyα/Heβ and IC/Heα, were measured and compared with the calculation results of a steady-state collisional-radiative model so that the temperature and density profiles with a spatial resolution of 55 µm were obtained within 200 µm from the target plane. The plasma parameters derived from the spatially integrated spectrum were used to calculate the ionization state distribution near the target surface with the steady-state model, and the result was compared with the ion charge state distribution measured with an Electrostatic Ion Analyzer (EIA) at a distance of 4.2 m from the target surface. The validity of the steady-state model and the difference between the calculated ion charge state distribution and that measured with the EIA are discussed.

The NSG-hIL6 Mouse As a Novel Murine Patient Derived Xenograft Model of Plasma Cell Dyscrasias for Study of Disease Biology and Therapeutic Development

Background Plasma cell dyscrasias include pre-malignant and malignant conditions spanning the spectrum from monoclonal gammopathy of undetermined significance (MGUS) to smoldering multiple myeloma (SMM) to active multiple myeloma (aMM) and include the disorders AL amyloidosis and plasma cell leukemia (PCL). Though the last 2 decades has yielded effective therapies against these disorders, there remain no reliably curative treatments, and complications due to multiple myeloma are most often the cause of death. A major reason for the lack of curative therapies is the dearth of relevant research models in which to study these diseases and test new drug candidates. Cell lines that do not reflect the biology of mainstream myeloma are currently the mainstay of disease modeling. Plasma cells do not survive well outside the bone marrow and to this point, little success has been made using primary tumors from patients to model disease. Thus, there is a significant need for more relevant models to build the next, hopefully curative, generation of therapeutics for these diseases. Research Significance We present a novel immunodeficient murine model able to engraft plasma cell dyscrasias from primary patient tumors and the ability to study basic biology and test efficacy of cellular therapies, representing a significant advance in this field. Methods The NSG-h(IL6) mouse, developed by Dr. Shultz, builds on the background NSG mouse that lacks adaptive immunity and has limited innate immunity. It expresses a BAC with a piece of human chromosome 7, containing the human IL-6 gene and all associated local promoter and enhancer elements. With the expertise of the stem cell and xenograft core facility (SCXC), mice were preconditioned with busulfan, and 1e6 mononuclear cells (MNCs) isolated from human myeloma patient marrow aspirate were injected into the murine femur. Blood and urine were sampled every 4-5 weeks and analyzed for the presence of human antibodies by ELISA. Deceased mice were sent for histology and their spleens and marrow analyzed for the presence of clonal plasma cells by flow cytometry. Serum protein electrophoresis (SPEP) and complete blood counts (CBC) were noted as hallmarks of disease. Samples from patients with MGUS, SMM, aMM (both newly diagnosed and relapsed/refractory), PCL and AL amyloidosis were engrafted into mice as above. Mice were treated with untraduced T-cells (UTD) or BCMA-directed CARTs 10 weeks after engraftment of active myeloma and blood was assayed for level of immunoglobulins to follow response. Results Analysis of murine serum and urine by ELISA revealed the presence of rising titers of human antibodies in all engrafted mice and the presence of an M-spike on SPEP. NSG-hIL6 mice conditioned with busulfan showed greater engraftment than non-IL6 containing mice and non-conditioned mice (7 vs 2 vs 0, p<0.005). Light chain specific ELISA showed a clear predominance of one light chain, congruent with the patient sample that was engrafted. Flow cytometric analysis of engrafted murine bone marrow showed the presence of light chain restricted plasma cells. Histology showed the presence of plasma cells in the marrow, spleen and liver of engrafted animals with IHC positivity for specific light chain and CD138. CBC showed pancytopenia (p<0.005) with anemia being most significant in engrafted vs. unengrafted animals. All fresh samples and nearly all frozen samples of MGUS, SMM, aMM, PCL and AL amyloidosis were able to be engrafted at high rates (>50% of mice). Mice injected with column separated CD138+ cells alone showed no engraftment vs. mice injected with total MNCs from the marrow of the same myeloma (3 vs 0, p<0.005 ). BCMA directed CARTs significantly decreased circulating antibody compared to UTD controls (p<0.005). Conclusion Using the NSG-hIL6 mouse, busulfan conditioning and intrafemur injections, we have been able to engraft all the major plasma cell dyscrasias as denoted by the presence of monoclonal human antibody in these mice and presence of light chain restricted plasma cells congruent with the patient's paraprotein. We have preliminarily shown that the ability to engraft disease is dependent on human supporting cells. Additionally, treatment with BCMA directed CARTs is showing a response. This simple model will allow for further preclinical testing of new agents against multiple myeloma and associated plasma cell neoplasms and allow for study of basic biology of these diseases. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Spatially and temporally resolved plasma formation on alumina target in microwave-enhanced laser-induced breakdown spectroscopy

Microwave energy was applied to the laser-induced breakdown spectroscopy (LIBS) of laser-ablated Al plasma using a helical antenna. The process of generating an enhanced laser ablation plasma was visualized with a high-speed camera. The time and space evolution of the plasma were investigated by changing the laser power, microwave energy, and microwave energy duration. The obtained raw images were converted into 8-bit 255 grayscale and binary black and white (BW) images and were analyzed using Matlab. Three major periods of plasma evolution were established based on the key physical process involved. Laser energy was the primary parameter involved in period 1, where laser ablation and initial plasma formation occurred. The microwaves had little significance at the beginning of the ablation process, as suggested by the minimal changes in plasma size and intensity. The microwaves controlled the expansion of the plasma and sustained breakdown in period 2. The post ablation breakdown of the material by microwaves sustained the enlargement of the plasma. The events leading to plasma dissipation comprised period 3, where the nonthermal plasma was sustained for 500 μs after the microwave was turned off. The effects of the laser and microwave parameters in the timeline of these periods were discussed. Complementary emission intensity measurements were also presented.

Varying magnetic field strength as an effective approach to boost up the plasma signal in laser-induced breakdown spectroscopy

Externally variable magnetic field was incorporated with the combination of laser induced breakdown spectroscopy (LIBS) to enhance the emission characteristics of aluminum (Al) plasma. Significant emission enhancement of laser induced plasma (LIP) was obtained at different magnetic field strengths, for instance, enhancement factors of about 1.2, 1.3 and 1.4 times were observed at field-strength of 0.4, 0.5 and 0.6 T, respectively. The electron-impact excitation rates and recombination process were increased at higher field-strengths, which led to the higher emission signal due the stronger plasma confinement by the field. The electron number density and electron temperature were measured using the spectroscopic techniques at several delay times. At higher field strengths, both electron density and electron excitation temperature showed an increased trend as compared to the case when No-field was applied. Hence, the research has significance for enhancing the plasma signal which led to improve the LIBS sensitivity.

Laser absorption spectroscopy on a transient aluminum plasma generated by excimer laser ablation

Transient Al plasma produced by excimer laser ablation in vacuum was investigated through laser absorption spectroscopy to probe the space-time evolution of neutral species. Spectrally integrating the absorbance, the ground state Al atoms column density was calculated. Typical decreasing trends in time (over a plasma lifetime of about 10 μs) and space (for distances in the range 0.5–8.5 mm from the target surface) were observed. The kinetic temperature of Al ground state species was also estimated from the recorded linewidths, in the assumption of a Doppler broadening mechanism. The resulted values displayed only weak time-fluctuations, while the time-averaged ones showed. a significant drop in few millimeters from the target, similarly to the column density behavior.

Quantitative spatiotemporal density evolution of aluminum heated purely by monochromatic electrons

A spatially resolved air-wedge shearing interferometer and shadowgraph diagnostic provides measurements of electron density with a resolution of ∼40 μm. A ∼100-ns-long, monoenergetic electron bunch at 19.8 MeV and a current of 1.4 kA (8.5×1014 e−) heats 100-μm-thick aluminum (Al) foils in a 1-mm-spot to Te∼1 eV. A 5-ns-long, ∼60 mJ, frequency doubled Nd:YAG laser probes the dense Al plasma. Electron densities up to 1020cm−3 are resolved; the maximum resolvable density is limited by opacity, transmission, and spatial fringe density achievable with the detector. This diagnostic provides measurements of the total phase shift, transmission, and electron density. Several measurements at different time slices provide the ability to determine the velocity of the leading edge of the shadowgraph and compare it to the motion of different density shells. These measurements are also compared to radiation hydrodynamics simulations. A rough quantitative agreement is shown between the hydro simulations and the measurements; there are differences in the exact density distributions.

Determining the temperature of aluminum plasma produced by laser‐induced breakdown spectroscopy based on its ultraviolet emission spectra

AbstractPlasma temperature and electron density are two important parameters describing the characteristics of plasma. The Aluminum plasma is produced by laser‐induced breakdown spectroscopy and its emission spectra are observed by a spectrometer with high resolution. Based on its discrete ultraviolet lines, pair‐line Boltzmann (PLB) approach is proposed to determine the temperature of plasma. These pair‐lines are with the same lower electronic state partially immune to self‐absorption influence. For comparison with Boltzmann two‐line method, the Al plasma is prepared at three different pulse energy levels. It is demonstrated that the accuracy of PLB is improved about three times by employing four ultraviolet pair‐lines. The electron density is estimated at different excited energy according to Stark line broadening of Al I 396.15 nm. Furthermore, the alloy of 7075‐Al is used as the sample target to generate the plasma to validate the PLB approach.

High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest

We present an experimental method to generate quasiperpendicular supercritical magnetized collisionless shocks. In our experiment, ambient nitrogen (N) plasma is at rest and well magnetized, and it has uniform mass density. The plasma is pushed by laser-driven ablation aluminum (Al) plasma. Streaked optical pyrometry and spatially resolved laser collective Thomson scattering clarify structures of plasma density and temperatures, which are compared with one-dimensional particle-in-cell simulations. It is indicated that just after the laser irradiation, the Al plasma is magnetized by a self-generated Biermann battery field, and the plasma slaps the incident N plasma. The compressed external field in the N plasma reflects N ions, leading to counterstreaming magnetized N flows. Namely, we identify the edge of the reflected N ions. Such interacting plasmas form a magnetized collisionless shock.

Is There Correlation Between Aluminum-Based Food Consumption and Plasma Level in Pregnant Women?

To explore the correlation of AL-based food consumption, known to have negative impact on health, and Al plasma levels with pregnancy status. A cross-sectional study was conducted on 75 participants, including 50 pregnant women. Al plasma levels were analyzed by ET-AAS. Exposure to food was positively correlated to Al mean plasma levels (reaching 2.12 ± 1.17μg/L) by 32%, specifically for potatoes, fruits, soft drinks, and ready meals. Usage of Al cookware was associated to higher Al plasma levels while pregnancy status was protective. Establishment of national recommendation to maintain lower levels of Al in food is required.

The Role of Non-Coding RNAs in the Pathogenesis of AL Amyloidosis

Background: Systemic light chain (AL) amyloidosis is a clonal plasma cell disorder characterized by deposition of misfolded immunoglobulin light chain products in vital organs, causing their dysfunction. All therapies used to treat AL patients are adapted from multiple myeloma (MM) and customized to the typically frail AL population. Hence, it is important to identify novel therapeutic targets for these patients. MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression and have a role in cancer development and progression. MiRNAs can be purified from serum, plasma and bone marrow (BM) and may be used as biomarkers to distinguish between patients and healthy individuals. Moreover, miRNA-mRNA interactions may determine the molecular mechanism involved in AL pathogenesis and may suggest novel therapeutic approaches. To date, knowledge about circulating or BM miRNAs involved in AL amyloidosis is lacking.Aims: To decipher specific miRNA expression profiles in AL amyloidosis compared to MM patients and healthy controls (HC) and to examine how miRNAs are involved in AL pathogenesis.Methods: miRNA expression profile was determined using the nCounter assay (NanoString technologies). RNA-Seq data was downloaded from GEO database (GSE175384), and was used to detect potential miRNA-mRNA targets, and enriched biological pathways by the bioinformatics tool Ingunity Pathway Analysis (IPA). MiRNA and gene expression profiles were validated by qRT-PCR in 60 AL, 60 MM and 10 HC samples. The effect of aberrantly expressed miRNAs on potential molecular targets was analyzed in ALMC1 cells by transfecting the cells with miRNA mimic, following qRT-PCR, Western blot analysis and Annexin-PI staining.Results: BM and plasma miRNAs were differentially expressed in AL amyloidosis compared to MM or HC. MiRs-9a-5p, 181a-5p, 199a-3p, 130a-3p, 145-5p and 301a-3p were differentially expressed between AL and MM samples and may be used as biomarkers for distinguish AL amyloidosis from MM. Moreover, we found that the differentially expressed miRNAs and mRNA in AL patients regulates key signaling pathways related to cell cycle and anti-apoptosis mechanisms including cytokine signaling, oxidative phosphorylation (OXPHOS), NFkB signaling, activation of MAPK and PI3K/AKT pathways, which are all linked to cancer cell growth, proliferation and therapeutic resistance, and therefore may be used as a therapeutic targets. Specifically, our analysis showed that genes related to mitochondrial activity were upregulated in AL patients (Figure 1), particularly the anti-apoptotic BCL2 family genes (BCL2, MCL1, and BCL2L1). MCL1 and BCL2L1 are predicted targets of miR-181a-5p that was downregulated in BM and plasma samples of AL patients compared to MM patients, indicating a possible interaction between these molecules. MiR-9-5p, which was also found to be downregulated in AL BM and plasma samples compared to MM patients, is predicted to have an indirect effect on the BCL2 family members through CREB molecule (Figure 1).The biological significance of miR-9-5p and miR-181a-5p was evaluated, by transfecting ALMC1 cell line with miRNA mimics. Overexpression of these miRNAs led to downregulation of the BCL2 family anti-apoptotic genes and induced apoptosis by Annexin V staining. These findings might explain the biological mechanism by which AL patients respond to the BCL2 inhibitor, venetoclax, as recently reported (Sidiqi et al, BCJ, 2020).Conclusions: We provide insight into the molecular mechanisms mediated by miRNAs and the aberrant expression of oncogenic/tumor suppressor genes. The differential expression of miRNAs in AL amyloidosis may be used to understand disease pathogenesis and predict risk of progression to AL amyloidosis among patients with known plasma cell disorders. Additionally, signaling pathways involved in AL amyloidosis, mediated by miRNAs, may assist in tailoring more specific treatments. [Display omitted] DisclosuresDispenzieri: Oncopeptides: Consultancy; Sorrento Therapeutics: Consultancy; Pfizer: Research Funding; Alnylam: Research Funding; Takeda: Research Funding; Janssen: Consultancy, Research Funding.

Daratumumab Activity Is Agnostic to Fc Gamma Receptor 3A (FcγR3A) 158 Genotype in Patients with Primary Refractory or Relapsed Systemic AL Amyloidosis

Introduction: Treatment targeted at the clonal plasma cells that produce the pathologic immunoglobulin light chain in patients with systemic AL amyloidosis, if effective and timely, can normalize serum free light chains resulting in organ responses and significantly improved overall survival. A third of patients with AL have no response to initial therapy, and over half of those who respond to initial therapy will relapse in 4 years; non-responders and relapsed patients with cardiac involvement are at especially high risk of shortened survival. Single agent daratumumab has been shown to have a response rate of 36% in relapsed refractory multiple myeloma patients (Lokhorst, Plesner et al. 2015). Daratumumab is an option for patients with AL who have marrow plasma cell burden > 10%, consistent with myeloma. Antibody- dependent cellular cytotoxicity is a mechanism of action of daratumumab, and this implicates recognition of the FC portion of the therapeutic antibody by FC receptors on effector cells such as macrophages and NK cells. A single nucleotide polymorphism at codon 158 of the FcγR3A receptor has been shown to affect the therapeutic efficacy of monoclonal antibodies(Mellor, Brown et al. 2013). The aim of this study was to assess hematologic and organ responses to daratumumab in a cohort of AL patients with primary refractory or relapsed clonal plasma cell disease and to test whether FcγR3A genotype influenced response to daratumumab.Materials and Methods: Patients with biopsy proven AL amyloidosis and organ involvement evaluated at Tufts Medical Center who received daratumumab were identified and evaluated for hematologic and organ responses according to consensus criteria (Comenzo, Reece et al. 2012, Palladini, Hegenbart et al. 2014). FcγR3a genotype for each patient was identified by PCR amplification and sequencing using genomic DNA from blood or marrow mononuclear cells. The translation of 158F or 158V in the alleles of the membrane-proximal extracellular domain was determined by T/G zygosity at nt559 in the gene sequence.Results: Fifteen patients with AL amyloidosis (λ=10, κ=5) who had primary refractory (no response after at least 2 cycles of initial therapy) (n = 5) or relapsed clonal plasma cell disease (n = 10) received daratumumab at standard doses at a median of 29 months from diagnosis (range, 2-107). Median age at diagnosis was 62 years (47-73) and 60% were male. The median lines of prior therapy were 3 (1-5). Eighty seven percent (n=13) had received bortezomib-based therapy and 53% (n=8) had undergone high-dose melphalan with autologous stem cell transplant. Nine patients had renal involvement (6 with stage 3), and 9 had cardiac involvement with a median NT-proBNP of 2373pg/ml (553-18021). All patients are alive with a median follow-up of 7 months (1-16). Hematologic responses were seen in 87% (CR=5, VPGR=8) with a median time to best response of 71 days. Forty four percent (n=4) had a renal response within an average of 107 days while 55% (n=5) achieved a cardiac response within an average of 149 days. Responses did not correlate with FcγR3A genotype (see figure below). Those with 158V/V or V/F had 3 CR, 3 VGPR and 1 no response (NR) while those with 158F/F had 2 CR, 5 VGPR and 1 NR. The ratio of FcγR3A 158 genotypes in patients with systemic AL amyloidosis has not previously been studied.Conclusions: Daratumumab achieved rapid hematologic responses in over 85% of patients with primary refractory or relapsed systemic AL amyloidosis with significant organ responses. Daratumumab activity was agnostic to FcγR3A 158 genotypes in this cohort of patients, in whom, of note, the distribution of genotypes is of interest. The basis for daratumumab activity may be linked to other mechanisms such as direct cytotoxicity or to the low fraction of cells in S-phase in AL plasma cell clones (Gertz, Kyle et al. 1989). Daratumumab is a very active agent in AL and its rapid clinical evaluation in patients with newly diagnosed AL is anticipated. [Display omitted] DisclosuresComenzo:Prothena: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Karyopharm: Research Funding; Takeda: Research Funding.