Bendamustine is safe and effective for lymphodepletion before tisagenlecleucel in patients with refractory or relapsed large B-cell lymphomas

BACKGROUND

Anti-CD19 chimeric antigen receptor T-cell immunotherapy (CAR-T) is now a standard treatment of relapsed or refractory B-cell non-Hodgkin lymphomas; however, a significant portion of patients do not respond to CAR-T and/or experience toxicities. Lymphodepleting chemotherapy is a critical component of CAR-T that enhances CAR-T-cell engraftment, expansion, cytotoxicity, and persistence. We hypothesized that the lymphodepletion regimen might affect the safety and efficacy of CAR-T.

PATIENTS AND METHODS

We compared the safety and efficacy of lymphodepletion using either fludarabine/cyclophosphamide (n = 42) or bendamustine (n = 90) before tisagenlecleucel in two cohorts of patients with relapsed or refractory large B-cell lymphomas treated consecutively at three academic institutions in the United States (University of Pennsylvania, n = 90; Oregon Health & Science University, n = 35) and Europe (University of Vienna, n = 7). Response was assessed using the Lugano 2014 criteria and toxicities were assessed by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 and, when possible, the American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading.

RESULTS

Fludarabine/cyclophosphamide led to more profound lymphocytopenia after tisagenlecleucel infusion compared with bendamustine, although the efficacy of tisagenlecleucel was similar between the two groups. We observed significant differences, however, in the frequency and severity of adverse events. In particular, patients treated with bendamustine had lower rates of cytokine release syndrome and neurotoxicity. In addition, higher rates of hematological toxicities were observed in patients receiving fludarabine/cyclophosphamide. Bendamustine-treated patients had higher nadir neutrophil counts, hemoglobin levels, and platelet counts, as well as a shorter time to blood count recovery, and received fewer platelet and red cell transfusions. Fewer episodes of infection, neutropenic fever, and post-infusion hospitalization were observed in the bendamustine cohort compared with patients receiving fludarabine/cyclophosphamide.

CONCLUSIONS

Bendamustine for lymphodepletion before tisagenlecleucel has efficacy similar to fludarabine/cyclophosphamide with reduced toxicities, including cytokine release syndrome, neurotoxicity, infectious and hematological toxicities, as well as reduced hospital utilization.

Amplification of flat laser pulse train

We present modeling and measurements of flattop amplification of a laser pulse train in a diode pumped Nd:YLF system. We establish a theoretical model, accounting for the transverse Gaussian shape of an amplified laser beam, in order to explain remaining slopes in the pulse train energy. The influence of the transverse Gaussian shape on the train's flatness has been experimentally verified. Based on the model we are able to increase the total amplification of a long train of infrared seed beam in the drive laser system at the Fermilab Accelerator Science and Technology facility. The single-pass amplifier improvements resulted in a gain of ∼7 with flat output pulse train for up to 1000 seed pulses.

On the role of electron energy distribution function in double frequency heating of electron cyclotron resonance ion source plasmas

Double frequency heating (DFH) is a tool to improve the output of highly charged ions particularly from modern electron cyclotron resonance ion source installations with very high RF-frequencies. In order to gain information on the DFH-mechanism and on the role of the lower injected frequency we have carried out a series of dedicated experiments where we have put emphasis on the creation of a discrete resonance surface also for this lower frequency. Our well-established method of inserting an emissive MD (metal-dielectric) liner into the plasma chamber of the source is used in these experiments as a tool of investigation. In this way, the electron temperature and density for both ECR zones is increased in a controlled manner, allowing conclusions on the role of the change of the electron-energy-distribution function with and without DFH.

The impact of plasma-wall interaction on the gas mixing efficiency in electron cyclotron resonance ion source

It is generally accepted that different effects are necessary to explain the gas mixing method of increasing the output of highly charged ions from an ECRIS. The two most important effects are the mass effect and the dilution effect. Their relative weights have not been determined experimentally yet, but it is generally assumed that the mass effect is dominant in standard ECRIS installations with stainless steel plasma chambers. In order to gain more insight into the physics of the gas mixing effect and in particular on the relevance of the dilution process, we have carried out a study where we have investigated the role of the plasma-wall interaction on the gas mixing effect. In this contribution, we shall discuss Charge state distributions spectra, measured at the Frankfurt ECRIS using different working gases, pure argon, a mixture of argon and oxygen, and argon mixed with neon.

Metal-dielectric structures for high power electron cyclotron resonance ion source

Metal-dielectric (MD)-structures in electron cyclotron resonance ion source (ECRIS) devices (partially) restore the plasma ambipolarity and supply cold electrons to the plasma. Both effects lead to an enhancement of the plasma electron density and temperature and significantly increase the performance of this type of ion source. At the same time, MD-structures are well suited to reduce the heat load on cold masses by Bremsstrahlung radiation. Here, we report on experiments at high microwave powers to test the practical use of MD-structures for new, high performance ECRISs with their much higher power densities. The comparatively long conditioning times can be shortened by covering only those parts of the source with MD-structures, which are essential for the improvement.

Enhanced confinement in electron cyclotron resonance ion source plasma

Power loss by plasma-wall interactions may become a limitation for the performance of ECR and fusion plasma devices. Based on our research to optimize the performance of electron cyclotron resonance ion source (ECRIS) devices by the use of metal-dielectric (MD) structures, the development of the method presented here, allows to significantly improve the confinement of plasma electrons and hence to reduce losses. Dedicated measurements were performed at the Frankfurt 14 GHz ECRIS using argon and helium as working gas and high temperature resistive material for the MD structures. The analyzed charge state distributions and bremsstrahlung radiation spectra (corrected for background) also clearly verify the anticipated increase in the plasma-electron density and hence demonstrate the advantage by the MD-method.

Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures

The influence of metal-dielectric (MD) layers (MD structures) inserted into the plasma chamber of an electron cyclotron resonance ion source (ECRIS) onto the production of electron bremsstrahlung radiation has been studied in a series of dedicated experiments at the 14 GHz ECRIS of the Institut für Kernphysik der Universität Frankfurt. The IKF-ECRIS was equipped with a MD liner, covering the inner walls of the plasma chamber, and a MD electrode, covering the plasma-facing side of the extraction electrode. On the basis of similar extracted currents of highly charged ions, significantly reduced yields of bremsstrahlung radiation for the "MD source" as compared to the standard (stainless steel) source have been measured and can be explained by the significantly better plasma confinement in a MD source as compared to an "all stainless steel" ECRIS.

The influence of ambipolarity on plasma confinement and on the performance of electron cyclotron resonance ion sources

Charge diffusion in an electron cyclotron resonance ion source (ECRIS) discharge is usually characterized by nonambipolar behavior. While the ions are transported to the radial walls, electrons are lost axially from the magnetic trap. Global neutrality is maintained via compensating currents in the conducting walls of the vacuum chamber. It is assumed that this behavior reduces the ion breeding times compared to a truly ambipolar plasma. We have carried out a series of dedicated experiments in which the ambipolarity of the ECRIS plasma was influenced by inserting special metal-dielectric structures (MD layers) into the plasma chamber of the Frankfurt 14 GHz ECRIS. The measurements demonstrate the positive influence on the source performance when the ECR plasma is changed toward more ambipolar behavior.

A status report of the multipurpose superconducting electron cyclotron resonance ion source

Intense heavy ion beam production with electron cyclotron resonance (ECR) ion sources is a common requirement for many of the accelerators under construction in Europe and elsewhere. An average increase of about one order of magnitude per decade in the performance of ECR ion sources was obtained up to now since the time of pioneering experiment of R. Geller at CEA, Grenoble, and this trend is not deemed to get the saturation at least in the next decade, according to the increased availability of powerful magnets and microwave generators. Electron density above 10(13) cm(-3) and very high current of multiply charged ions are expected with the use of 28 GHz microwave heating and of an adequate plasma trap, with a B-minimum shape, according to the high B mode concept [S. Gammino and G. Ciavola, Plasma Sources Sci. Technol. 5, 19 (1996)]. The MS-ECRIS ion source has been designed following this concept and its construction is underway at GSI, Darmstadt. The project is the result of the cooperation of nine European institutions with the partial funding of EU through the sixth Framework Programme. The contribution of different institutions has permitted to build in 2006-2007 each component at high level of expertise. The description of the major components will be given in the following with a view on the planning of the assembly and commissioning phase to be carried out in fall 2007. An outline of the experiments to be done with the MS-ECRIS source in the next two years will be presented.

Hybrid cerenkov mode in a resonant medium

Energy stored in a resonant medium may be used to amplify the Cerenkov radiation generated by a small driving bunch. The hybrid eigenmode of the system is a combination of Cerenkov radiation and eigenmode of the resonant medium. In the vicinity of the resonant frequency of the medium and when Cerenkov condition is satisfied, the eigenfrequency has an imaginary part. The latter occurs in a relatively limited range of energies of the driving bunch and it depends on the guiding geometry and on the population inversion. Simulation results of electron acceleration using this eigenmode are presented.

Coupling of symmetric and asymmetric modes in a high-power, high-efficiency traveling-wave amplifier

A three-dimensional model has been developed for the investigation of the coupling of symmetric (TM01) and asymmetric (HEM11) modes in a high-power, high-efficiency traveling-wave amplifier. In the framework of a simplified model it is shown that the coupling between these two modes is determined by a single parameter that depends on the beam characteristics. For a specific set of parameters corresponding to operation at 35 GHz, simulations indicate that an initial HEM11 power of 0.5 MW at the input end is sufficient to deflect electrons to the wall. The build-up of this parasitic mode is investigated over many round trips of the wave in the structure and a threshold criterion for self-sustain oscillation is established. Finally a way for suppressing the HEM11 mode is analyzed.

Attitudes of family physicians to nonconventional therapies. A challenge to science as the basis of therapeutics

Eighty-nine Israeli family physicians responded to a questionnaire on their experience with nonconventional therapies (NCTs) and their opinions about the scientific basis and clinical efficacy of these treatments. They were also asked whether they thought that NCTs should be incorporated into regular medical practice. Seventeen percent of the physicians had formal training in some form of NCT and 11% thought the scientific basis of these treatments was sound; however, a majority (54%) thought they may be clinically useful. Forty-two percent had referred patients for such treatments. The majority thought that NCTs should be incorporated into medical practice. Our survey suggests that many physicians are not using the tools of scientific critical appraisal in forming their views on NCTs.

Effect of blood glucose control on retinal vascular permeability in insulin-dependent diabetes mellitus

Thirteen patients were instructed in a technique of self-management of insulin-dependent diabetes mellitus, using multiple home-monitored blood glucose determinations and multiple injections of regular insulin in conjunction with once-daily Ultra Lente insulin. Hemoglobin A1c and quantitative fluorescein fluorophotometry were used to assess blood glucose control and retinal permeability, respectively. In those patients achieving normal blood glucose control, retinal vascular leakage was statistically identical to that of a nondiabetic control population. In those patients less well controlled, retinal permeability did not differ statistically from values observed in a population of insulin-dependent diabetic patients under "standard" control. It is concluded that with "tight" control of blood sugar and normalized A1c hemoglobin, retinal permeability similarly is normalized.