Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes.

To fully harness the potential of abundant metal coordination complex photosensitizers, a detailed understanding of the molecular properties that dictate and control the electronic excited-state population dynamics initiated by light absorption is critical. In the absence of detectable luminescence, optical transient absorption (TA) spectroscopy is the most widely employed method for interpreting electron redistribution in such excited states, particularly for those with a charge-transfer character. The assignment of excited-state TA spectral features often relies on spectroelectrochemical measurements, where the transient absorption spectrum generated by a metal-to-ligand charge-transfer (MLCT) electronic excited state, for instance, can be approximated using steady-state spectra generated by electrochemical ligand reduction and metal oxidation and accounting for the loss of absorptions by the electronic ground state. However, the reliability of this approach can be clouded when multiple electronic configurations have similar optical signatures. Using a case study of Fe(II) complexes supported by benzannulated diarylamido ligands, we highlight an example of such an ambiguity and show how time-resolved X-ray emission spectroscopy (XES) measurements can reliably assign excited states from the perspective of the metal, particularly in conjunction with accurate synthetic models of ligand-field electronic excited states, leading to a reinterpretation of the long-lived excited state as a ligand-field metal-centered quintet state. A detailed analysis of the XES data on the long-lived excited state is presented, along with a discussion of the ultrafast dynamics following the photoexcitation of low-spin Fe(II)-Namido complexes using a high-spin ground-state analogue as a spectral model for the 5T2 excited state.

Observation of a Picosecond Light-Induced Spin Transition in Polymeric Nanorods.

Spin transition (ST) materials are attractive for developing photoswitchable devices, but their slow material transformations limit device applications. Size reduction could enable faster switching, but the photoinduced dynamics at the nanoscale remains poorly understood. Here, we report a femtosecond optical pump multimodal X-ray probe study of polymeric nanorods. Simultaneously tracking the ST order parameter with X-ray emission spectroscopy and structure with X-ray diffraction, we observe photodoping of the low-spin-lattice within ∼150 fs. Above a ∼16% photodoping threshold, the transition to the high-spin phase occurs following an incubation period assigned to vibrational energy redistribution within the nanorods activating the molecular spin switching. Above ∼60% photodoping, the incubation period disappears, and the transition completes within ∼50 ps, preceded by the elastic nanorod expansion in response to the photodoping. These results support the feasibility of ST material-based GHz optical switching applications.

Early de-escalation of antibiotic therapy in hospitalized cellular therapy adult patients with febrile neutropenia.

Febrile neutropenia (FN) is an oncologic emergency frequently encountered in hematopoietic cell transplant (HCT) and chimeric antigen receptor (CAR) T-cell therapy patients, which requires immediate initiation of broad-spectrum antibiotics. Data regarding antibiotic de-escalation (DE) in neutropenic patients are limited, and guideline recommendations vary. A clinical protocol for antibiotic DE of broad-spectrum agents was implemented if patients were afebrile after 72 hours and had no clinical evidence of infection. The primary endpoint was the difference in the number of antibiotic therapy days between the pre-and post-DE protocol implementation group. Secondary endpoints included rates of subsequent bacteremia during index hospitalization, 30-day mortality, and hospital length of stay. Retrospective chart reviews were conducted to assess outcomes for patients who received allogeneic HCT, autologous HCT, or CAR T-cell therapy under the antibiotic de-escalation protocol (post-DE) compared to those who did not (pre-DE). The pre-DE group underwent HCT/CAR T-cell from February 2018 through September 2018 (n=64), and the post-DE group from February 2019 through September 2019 (n=67). The median duration of antibiotics was significantly lower in the post-DE group (6 days; range 3-60 days) compared to the pre-DE group (8 days; range 3-31 days) (p=0.034). There were no differences in any secondary endpoints. We conclude that antibiotic DE in neutropenic HCT or CAR T-cell therapy patients treated with broad-spectrum antibiotics for at least three days who are afebrile and without documented infection appears to be a safe and effective practice. Adopting it significantly reduces the number of days of antibiotics without compromising patient outcomes.

Characterization of Deformational Isomerization Potential and Interconversion Dynamics with Ultrafast X-ray Solution Scattering.

Dimeric complexes composed of d8 square planar metal centers and rigid bridging ligands provide model systems to understand the interplay between attractive dispersion forces and steric strain in order to assist the development of reliable methods to model metal dimer complexes more broadly. [Ir2 (dimen)4]2+ (dimen = para-diisocyanomenthane) presents a unique case study for such phenomena, as distortions of the optimal structure of a ligand with limited conformational flexibility counteract the attractive dispersive forces from the metal and ligand to yield a complex with two ground state deformational isomers. Here, we use ultrafast X-ray solution scattering (XSS) and optical transient absorption spectroscopy (OTAS) to reveal the nature of the equilibrium distribution and the exchange rate between the deformational isomers. The two ground state isomers have spectrally distinct electronic excitations that enable the selective excitation of one isomer or the other using a femtosecond duration pulse of visible light. We then track the dynamics of the nonequilibrium depletion of the electronic ground state population─often termed the ground state hole─with ultrafast XSS and OTAS, revealing a restoration of the ground state equilibrium in 2.3 ps. This combined experimental and theoretical study provides a critical test of various density functional approximations in the description of bridged d8-d8 metal complexes. The results show that density functional theory calculations can reproduce the primary experimental observations if dispersion interactions are added, and a hybrid functional, which includes exact exchange, is used.

A US perspective on closing the carbon cycle to defossilize difficult-to-electrify segments of our economy.

Electrification to reduce or eliminate greenhouse gas emissions is essential to mitigate climate change. However, a substantial portion of our manufacturing and transportation infrastructure will be difficult to electrify and/or will continue to use carbon as a key component, including areas in aviation, heavy-duty and marine transportation, and the chemical industry. In this Roadmap, we explore how multidisciplinary approaches will enable us to close the carbon cycle and create a circular economy by defossilizing these difficult-to-electrify areas and those that will continue to need carbon. We discuss two approaches for this: developing carbon alternatives and improving our ability to reuse carbon, enabled by separations. Furthermore, we posit that co-design and use-driven fundamental science are essential to reach aggressive greenhouse gas reduction targets.

Impact of age, obesity, and renal impairment on outcomes after autologous stem cell transplantation for patients with newly diagnosed multiple myeloma.

INTRODUCTION: There remains a need to determine whether certain subgroups of newly diagnosed multiple myeloma (NDMM) derive the same benefit from high-dose chemotherapy-autologous stem cell transplant (HDT-ASCT). We describe our institutional experience highlighting the impact of age, obesity, and renal impairment on outcomes after HDT-ASCT for patients with NDMM in a real-world setting. METHODS: A total of 449 consecutive patients were included in this retrospective analysis. RESULTS: No difference in median progression free survival or overall survival was seen for patients with age > 65, body mass index (BMI) > 30 kg/m2, or estimated glomerular filtration rate < 60 mL/min/1.73 m2 when compared to those without these characteristics. From a safety standpoint, there were no differences in the incidence of transplant-related mortality or secondary malignancy among subgroups. CONCLUSION: For patients with NDMM undergoing HDT-ASCT, there is no difference in outcomes based on age, BMI, or renal function, and the presence of one or more of these factors should not preclude patients from HDT-ASCT.

Early versus standard management of chimeric antigen receptor therapy toxicities and management's impact on safety and efficacy.

BACKGROUND: Cytokine release syndrome (CRS) and immune effector cell-associated neurologic syndrome (ICANS) are well-documented toxicities of CAR T-cell therapy. To mitigate excessive toxicity, our center has formulated treatment protocols (early vs. standard) for timely management of CRS and ICANS with tocilizumab and/or corticosteroids. METHODS: This retrospective, single-center analysis included patients treated with CAR T-cell therapy. The goal was to describe the association of two management protocols with toxicity and efficacy outcomes. RESULTS: Fifty-five percent of the 40 patients assigned to early management, out of which 5% and 9% developed grade 3+ CRS and ICANS, respectively. Seventy-seven percent and 41% of these patients received tocilizumab and corticosteroids, respectively. Forty-five percent of patients were stratified as standard management, out of which 0% and 11% developed grade 3+ CRS and ICANS, respectively. Seventeen percent and 28% of these patients received tocilizumab and corticosteroids, respectively. The day +90 overall response rate (ORR) for all patients was 63%, with an ORR of 89% for those managed per early management versus 50% for those managed per standard protocol. CONCLUSION: Early use of tocilizumab and corticosteroids is effective in preventing excessive CAR-T-related toxicities with no negative impact on efficacy.

Impact of race and ethnicity on outcomes after autologous stem cell transplantation for patients with newly diagnosed multiple myeloma.

Non-Hispanic Black patients are disproportionally affected by multiple myeloma (MM) and whether efficacy outcomes after autologous stem cell transplant (ASCT) differ by race and ethnicity remains an area of active investigation. This study included 449 patients enriched with a large proportion of non-Hispanic Black patients and sought to highlight the impact of race and ethnicity on outcomes after HDT-ASCT for patients with newly diagnosed MM. We found induction chemotherapy followed by high-dose therapy-ASCT and maintenance chemotherapy is associated with long-term PFS and OS, regardless of race or ethnicity.

Solution phase high repetition rate laser pump x-ray probe picosecond hard x-ray spectroscopy at the Stanford Synchrotron Radiation Lightsource.

We present a dedicated end-station for solution phase high repetition rate (MHz) picosecond hard x-ray spectroscopy at beamline 15-2 of the Stanford Synchrotron Radiation Lightsource. A high-power ultrafast ytterbium-doped fiber laser is used to photoexcite the samples at a repetition rate of 640 kHz, while the data acquisition operates at the 1.28 MHz repetition rate of the storage ring recording data in an alternating on-off mode. The time-resolved x-ray measurements are enabled via gating the x-ray detectors with the 20 mA/70 ps camshaft bunch of SPEAR3, a mode available during the routine operations of the Stanford Synchrotron Radiation Lightsource. As a benchmark study, aiming to demonstrate the advantageous capabilities of this end-station, we have conducted picosecond Fe K-edge x-ray absorption spectroscopy on aqueous [FeII(phen)3]2+, a prototypical spin crossover complex that undergoes light-induced excited spin state trapping forming an electronic excited state with a 0.6-0.7 ns lifetime. In addition, we report transient Fe Kß main line and valence-to-core x-ray emission spectra, showing a unique detection sensitivity and an excellent agreement with model spectra and density functional theory calculations, respectively. Notably, the achieved signal-to-noise ratio, the overall performance, and the routine availability of the developed end-station have enabled a systematic time-resolved science program using the monochromatic beam at the Stanford Synchrotron Radiation Lightsource.

Ferricyanide photo-aquation pathway revealed by combined femtosecond Kß main line and valence-to-core x-ray emission spectroscopy.

Reliably identifying short-lived chemical reaction intermediates is crucial to elucidate reaction mechanisms but becomes particularly challenging when multiple transient species occur simultaneously. Here, we report a femtosecond x-ray emission spectroscopy and scattering study of the aqueous ferricyanide photochemistry, utilizing the combined Fe Kß main and valence-to-core emission lines. Following UV-excitation, we observe a ligand-to-metal charge transfer excited state that decays within 0.5 ps. On this timescale, we also detect a hitherto unobserved short-lived species that we assign to a ferric penta-coordinate intermediate of the photo-aquation reaction. We provide evidence that bond photolysis occurs from reactive metal-centered excited states that are populated through relaxation of the charge transfer excited state. Beyond illuminating the elusive ferricyanide photochemistry, these results show how current limitations of Kß main line analysis in assigning ultrafast reaction intermediates can be circumvented by simultaneously using the valence-to-core spectral range.

Prophylactic Trimethoprim-Sulfamethoxazole for Allogeneic Hematopoietic Stem Cell Transplant Recipients During the Pre-engraftment Period.

BACKGROUND: Our institution has used trimethoprim-sulfamethoxazole (TMP-SMX) as the antibacterial agent of choice for infection prophylaxis during the pre-engraftment period in the allogeneic transplant (allo-HCT) population. METHODS: This retrospective, single center study was developed to compare the safety of that antibacterial prophylaxis to fluoroquinolones in allo-HCT. The primary endpoint was time to neutrophil engraftment. RESULTS: A total of 366 patients were reviewed (TMP-SMX n = 332, fluoroquinolone n = 34). No difference in days to neutrophil engraftment was found (median 15 versus 16 days, p = 0.62). Hyperkalemia was more common in the TMP-SMX cohort (32.2% versus 14.7%, p = 0.035); this did not contribute to a higher rate of agent discontinuation or arrhythmia. There was no significant difference in the incidence of neutropenic fever; however, those in the TMP-SMX cohort were more likely to have microbiologically confirmed bacteremia (24.1% versus 8.8% respectively, p = 0.043). There was no significant difference in infections. No long-term implication of prophylactic antibacterial agent selection was observed in terms of graft-versus-host-disease, underlying disease relapse, or mortality. CONCLUSION: The use of TMP-SMX was associated with a higher likelihood of bacteremia and hyperkalemia; however, this did not result in increased hospital stay, escalation of care, or mortality. The use of TMP-SMX for prophylaxis during the pre-engraftment period for allo-HCT recipients is safe and effective.

Newly approved and forthcoming T-cell-redirecting bispecific antibodies for the treatment of relapsed/refractory multiple myeloma.

OBJECTIVE: Summarize the background, clinical trials, and place in therapy for the newly Food and Drug Administration (FDA) approved and forthcoming bispecific antibodies for relapsed/refractory (R/R) multiple myeloma. DATA SOURCES: A search of the PubMed database was conducted using the following search terms: B-cell maturation antigen (BCMA), teclistamab, myeloma, BsAbs, GPRC5D, and bispecific. Ongoing clinical trials as well as abstracts from ASH and ASCO evaluating the efficacy and safety of novel agents were evaluated. Prescribing information was also reviewed. SUMMARY: For patients with R/R multiple myeloma who have failed available therapies, treatment options are limited and survival is short. The FDA recently approved teclistamab, a T-cell-redirecting bispecific antibody, in patients with R/R multiple myeloma who have failed four prior lines of therapy. Teclistamab targets both CD3 expressed on T-cells and BCMA expressed on the surface of myeloma cells, mediating T-cell activation and lysis of plasma cells that express BCMA. Accelerated approval was granted based upon the results of the MajesTEC-1 study, which showed a durable response in a high proportion of heavily pretreated patients. Teclistamab is the first bispecific antibody approved for use in patients with multiple myeloma and the fourth approved agent targeting BCMA. Additional T-cell redirecting bispecific antibodies for use in multiple myeloma are also currently being studied. CONCLUSION: Teclistamab is the newest agent granted FDA approval for use in R/R multiple myeloma and represents a promising new option for patients. Ongoing trials are investigating teclistamab and other novel bispecific antibodies in the upfront and R/R setting.

Fever Characteristics and Impact on Safety and Efficacy of Chimeric Antigen Receptor T-Cell Therapy.

BACKGROUND: Fever is a hallmark symptom of cytokine release syndrome (CRS) after chimeric antigen receptor (CAR) T-cell therapy. Fever characteristics and the impact of fever on safety and efficacy post CAR T are not well understood. We sought to explore the impact of fever and its characteristics on safety and efficacy post CAR T-cell therapy. PATIENTS AND METHODS: We reviewed 40 patients with various hematologic malignancies (non-Hodgkin lymphoma, acute lymphoblastic leukemia, multiple myeloma) treated with CAR T-cell therapy between March 2019 and March 2022. We evaluated all patients who developed fever after CAR T infusion and analyzed the association of fever with toxicity (CRS and neurotoxicity) and efficacy (overall response (ORR) and complete response (CR) at day +90 post CAR T infusion). Fever was defined as per Lee criteria (equal to or greater than 38°C). CRS and immune-effector cell associated neurotoxicity syndrome (ICANS) were graded using American Society for Transplantation and Cellular Therapy grading system. RESULTS: Fever occurred in 75% (30/40) of patients. Rates of all grade and grade 3+ CRS and ICANS were 75%, 2%, 33% and 10%, respectively. Fever occurred within 24 and 72 hours after CAR T infusion in 40% and 53% of patients, respectively. Fifty percent of patients received tocilizumab (toci) for CRS. After the first dose of toci, fever recurred in 38% of the patients, of which 67% had recurrence within 24 hours. Day +90 CR rates were 43% and 10% in patients with and without fever, respectively (Table 3). CONCLUSION: While fever is common after CAR T-cell therapy, early-onset and higher magnitude do not appear to affect safety or efficacy of CAR T. Absence of fever may affect response to CAR T.

Impact of Cytogenetic Abnormalities, Induction and Maintenance Regimens on Outcomes After High-Dose Chemotherapy and Autologous Stem Cell Transplantation in Patients With Newly Diagnosed Multiple Myeloma: A Decade-Long Real-World Experience.

Background: High-dose chemotherapy and autologous stem cell transplant (HDT-ASCT) has become a standard of care for transplant eligible newly diagnosed multiple myeloma (NDMM) patients. While cytogenetic abnormalities have been shown to affect outcomes after HDT-ASCT in clinical trials, these trials often exclude or underrepresent elderly patients with comorbidities and those belonging to ethnic minorities. We describe our institutional experience highlighting the impact of high-risk cytogenetic abnormalities (HRCAs) on outcomes after HDT-ASCT for NDMM patients. Methods: A total of 449 patients with NDMM who underwent HDT-ASCT between February 2012 and August 2022 were included in this retrospective analysis. HRCAs included the presence of one or more of: deletion 17p, t(14;16), t(4;14), and amplification 1q. Survival analyses, including progression-free survival (PFS) and overall survival (OS), were performed using Kaplan-Meier estimator. Results: With a median follow-up of 29 (1 - 128) months for the entire patient population, the best overall response rate for the patients with HRCAs was lower compared to those with standard risk cytogenetics (90% vs. 96%; P = 0.01). Patients with HRCAs had an inferior PFS compared to patients with standard-risk cytogenetics (29 vs. 58 months; P < 0.001) without a difference in OS (70 months vs. not reached; P = 0.13). Conclusions: In a multivariable analysis adjusting for factors including age, race, and comorbidities, HRCAs, non-lenalidomide-based maintenance, non-proteasome inhibitor-based maintenance, and age greater than 65 were associated with inferior PFS. Amongst these factors, only non-lenalidomide-based maintenance was associated with inferior OS.