Associations of circulating T-cell subsets in carotid artery stiffness: the Multi-Ethnic Study of Atherosclerosis.

Background: Arterial stiffness measured by total pulse wave velocity (T-PWV) is associated with increased risk of multiple age-related diseases. T-PWV can be described by structural (S-PWV) and load-dependent (LD-PWV) arterial stiffening. T-cells have been associated with arterial remodeling, blood pressure, and arterial stiffness in humans and animals; however, it is unknown whether T-cells are related to S-PWV or LD-PWV. Therefore, we evaluated the cross-sectional associations of peripheral T-cell subpopulations with T-PWV, S-PWV, and LD-PWV stiffness. Methods: Peripheral blood T-cells were characterized using flow cytometry and the carotid artery was measured using B-mode ultrasound to calculate T-PWV at the baseline examination in a subset of the Multi-Ethnic Study of Atherosclerosis (MESA, n=1,984). A participant-specific exponential model was used to calculate S-PWV and LD-PWV based on elastic modulus and blood pressure gradients. The associations between five primary (p-significance<0.01) and twenty-five exploratory (p-significance<0.05) immune cell subpopulations, per 1-SD increment, and arterial stiffness measures were assessed using adjusted, linear regressions. Results: For the primary analysis, higher CD4+CD28-CD57+ T-cells were associated with higher LD-PWV (ß=0.04 m/s, p<0.01) after adjusting for co-variates. For the exploratory analysis, T-cell subpopulations that commonly shift with aging towards memory and differentiated/immunosenescent phenotypes were associated with greater T-PWV, S-PWV, and LD-PWV after adjusting for co-variates. Conclusions: In this cross-sectional study, several T-cell subpopulations commonly associated with aging were related with measures of arterial stiffness. Longitudinal studies that examine changes in T-cell subpopulations and measures of arterial stiffness are warranted.

Immune cell profiling of the ICAM1 p.K56M heart failure with preserved ejection fraction risk variant.

AIMS: Intercellular adhesion molecule-1 (ICAM-1) facilitates inflammation via leucocyte recruitment and has been implicated in heart failure with preserved ejection fraction (HFpEF). Approximately 35% of African American individuals carry a copy of an ICAM1 missense variant (rs5491; p.K56M), which is associated with an increased risk of HFpEF. The pathways by which rs5491 increases HFpEF risk are not well defined. We evaluated the circulating immune cell profile of rs5491. METHODS: Among African American individuals in the Multi-Ethnic Study of Atherosclerosis, we evaluated the associations of rs5491 with 29 circulating peripheral blood mononuclear cell subsets. The top immune cells were then related to echocardiographic measures of structure and function. RESULTS: Among 502 individuals with immune cell profiling (mean age 63 years, 51% female), 191 individuals (38%) had at least one copy of rs5491. Each additional rs5491 allele was significantly associated with higher proportions of Tc17 CD8+ cytotoxic T cells (ß = 1.34, SE = 0.45, P = 9.5 × 10-5) and Tc2 CD8+ cytotoxic T cells (ß = 1.19, SE = 0.44, P = 0.00012). There were no other associations noted between rs5491 and the remaining immune cells. A higher proportion of Tc17 cells was significantly associated with a higher left ventricular ejection fraction, E/e' average and right ventricular systolic pressure (RVSP), while a higher proportion of Tc2 cells was significantly associated with a higher RVSP. CONCLUSIONS: The ICAM1 p.K56M variant (rs5491) carries a distinct and inflammatory T-cell subset profile. These cytotoxic T cells are in turn associated with alterations in cardiac function and adverse haemodynamics later in life, thus providing insight into pathways by which rs5491 may increase the risk of HFpEF.

Gene expression and splicing QTL analysis of blood cells in African American participants from the Jackson Heart Study.

Most gene expression and alternative splicing quantitative trait loci (eQTL/sQTL) studies have been biased toward European ancestry individuals. Here, we performed eQTL and sQTL analyses using TOPMed whole-genome sequencing-derived genotype data and RNA-sequencing data from stored peripheral blood mononuclear cells in 1,012 African American participants from the Jackson Heart Study (JHS). At a false discovery rate of 5%, we identified 17,630 unique eQTL credible sets covering 16,538 unique genes; and 24,525 unique sQTL credible sets covering 9,605 unique genes, with lead QTL at P < 5e-8. About 24% of independent eQTLs and independent sQTLs with a minor allele frequency > 1% in JHS were rare (minor allele frequency < 0.1%), and therefore unlikely to be detected, in European ancestry individuals. Finally, we created an open database, which is freely available online, allowing fast query and bulk download of our QTL results.

Immune cell phenotypes and mortality in the Framingham Heart Study.

BACKGROUND: Global life expectancy is rising, with the 60 + age group projected to hit 2 billion by 2050. Aging impacts the immune system. A notable marker of immune system aging is the presence of Aging-Related Immune Cell Phenotypes (ARIPs). Despite their importance, links between immune cell phenotypes including ARIPs and mortality are underexplored. We prospectively investigated 16 different immune cell phenotypes using flow cytometry and IL-6 in relation to survival outcome among dementia-free Framingham Heart Study (FHS) offspring cohort participants who attended the seventh exam (1998-2001). RESULTS: Among 996 participants (mean age 62 years, range 40 to 88 years, 52% female), the 19-year survival rate was 65%. Adjusting for age, sex, and cytomegalovirus (CMV) serostatus, higher CD4/CD8 and Tc17/CD8 + Treg ratios were significantly associated with lower all-cause mortality (HR: 0.86 [0.76-0.96], 0.84 [0.74-0.94], respectively), while higher CD8 regulatory cell levels (CD8 + CD25 + FoxP3 +) were associated with increased all-cause mortality risk (HR = 1.17, [1.03-1.32]). Elevated IL-6 levels correlated with higher all-cause, cardiovascular, and non-cardiovascular mortality (HR = 1.43 [1.26-1.62], 1.70 [1.31-2.21], and 1.36 [1.18-1.57], respectively). However, after adjusting for cardiovascular risk factors and prevalent cancer alongside age, sex, and CMV, immune cell phenotypes were no longer associated with mortality in our cohort. Nonetheless, IL-6 remained significantly associated with all-cause and cardiovascular mortality (HRs: 1.3 [1.13-1.49], 1.5 [1.12-1.99], respectively). CONCLUSIONS: In 19-year follow-up, higher Tc17/CD8 + Treg and CD4/CD8 ratios were associated with lower all-cause mortality, while the CD8 + CD25 + FoxP3 + (CD8 + Treg) phenotype showed increased risk. Elevated IL-6 levels consistently correlated with amplified mortality risks. These findings highlight the links between immune phenotypes and mortality, suggesting implications for future research and clinical considerations.

Panel Interview of ONcology practices with Emergent Experience of teclistamab in the Real world: the TecPIONEER Study.

OBJECTIVE: To understand clinicians' current teclistamab step-up dosing (SUD) model and how they envision future administration models, as well as perceived barriers and facilitators to these models in day-to-day clinical practice. METHODS: Interviews of clinicians with RW experience administering teclistamab, with a subsequent roundtable discussion to discuss interview findings. Topics of interest included managing adverse events (AE), and handling logistics of SUD and transition of care (ToC). RESULTS: 20 clinicians representing 19 practices participated. Of 14 practices administering inpatient teclistamab SUD, 12 (86%) utilized a single admission. A day 1-3-5 dosing schedule with a 7-day length of stay was planned in 10/14 (71%). The remaining 5 practices employed outpatient or hybrid SUD. SUD models depended on cellular therapy experience, patient volume, and monitoring capabilities. Clinicians desired to administer SUD outpatient for convenience and reduced healthcare resource use. 11% of practices reported using tocilizumab for cytokine release syndrome (CRS) prophylaxis, whilst it was uniformly used to treat grade 2+ CRS. Corticosteroids were the preferred treatment for neurotoxicity. Infection prophylaxis with intravenous immunoglobulin was reported by 89% of practices. Patient- and institution-level factors affected decision-making of transitioning patients back to referring sites after SUD. CONCLUSION: The results consolidated practice-based experiences and indicated diverse RW SUD models and patient management strategies in practices with familiarity with teclistamab AE management and ToC protocols. Inpatient SUD is common, with expectations that approaches will evolve toward outpatient or community-based administration. Further research is needed to investigate outcomes of different care models and AE management strategies.

Multiple myeloma is a blood cancer that forms in plasma cells. Teclistamab is a new treatment for patients with multiple myeloma who have received prior treatment but for whom their multiple myeloma has come back or stopped responding to treatment multiple times. Because teclistamab works differently than other existing multiple myeloma treatments, there is a need to understand how oncologists who have experience with teclistamab are managing their patients in order to inform best practices for use by more healthcare providers. We interviewed oncologists that treat patients with multiple myeloma to understand their experiences with teclistamab, including how they manage initial dosing (step-up dosing) processes, treat adverse events, and transition patients to outpatient or external clinics for continued care. Most practices were administering step-up dosing of teclistamab in an inpatient setting soon after teclistamab became a treatment option, with a high level of desire to move the initial dosing to an outpatient setting in the near future. Those that were already administering step-up dosing in an outpatient setting had models unique to their practice. Oncologists described numerous processes for monitoring and managing adverse events of the treatment, including treating patients with preventative medications and regularly monitoring vital signs throughout step-up dosing. Oncologists expected that their teclistamab administration processes will likely evolve over time as they gain more familiarity with the treatment, and will need to consider patient-level factors to administer step-up dosing in an outpatient setting.

Determinants of mosaic chromosomal alteration fitness.

Clonal hematopoiesis (CH) is characterized by the acquisition of a somatic mutation in a hematopoietic stem cell that results in a clonal expansion. These driver mutations can be single nucleotide variants in cancer driver genes or larger structural rearrangements called mosaic chromosomal alterations (mCAs). The factors that influence the variations in mCA fitness and ultimately result in different clonal expansion rates are not well understood. We used the Passenger-Approximated Clonal Expansion Rate (PACER) method to estimate clonal expansion rate as PACER scores for 6,381 individuals in the NHLBI TOPMed cohort with gain, loss, and copy-neutral loss of heterozygosity mCAs. Our mCA fitness estimates, derived by aggregating per-individual PACER scores, were correlated (R2 = 0.49) with an alternative approach that estimated fitness of mCAs in the UK Biobank using population-level distributions of clonal fraction. Among individuals with JAK2 V617F clonal hematopoiesis of indeterminate potential or mCAs affecting the JAK2 gene on chromosome 9, PACER score was strongly correlated with erythrocyte count. In a cross-sectional analysis, genome-wide association study of estimates of mCA expansion rate identified a TCL1A locus variant associated with mCA clonal expansion rate, with suggestive variants in NRIP1 and TERT.

Pulmonary Hypertension and Anastrozole (PHANTOM): A Randomized, Double-Blind, Placebo-Controlled Trial.

RATIONALE: Inhibition of aromatase with anastrozole reduces pulmonary hypertension in experimental models. OBJECTIVES: We aimed to determine whether anastrozole improved six-minute walk distance (6MWD) at six months in pulmonary arterial hypertension (PAH). METHODS: We performed a randomized, double-blind, placebo-controlled Phase II clinical trial of anastrozole in subjects with PAH at seven centers. Eighty-four post-menopausal women and men with PAH were randomized in a 1:1 ratio to receive anastrozole 1 mg or placebo by mouth daily, stratified by sex using permuted blocks of variable sizes. All subjects and study staff were masked. The primary outcome was the change from baseline in 6MWD at six months. Using intent-to-treat analysis, we estimated the treatment effect of anastrozole using linear regression models adjusted for sex and baseline 6MWD. Assuming 10% loss to follow-up, we anticipated having 80% power to detect a difference in the change in 6MWD of 22 meters. MEASUREMENTS AND MAIN RESULTS: Forty-one subjects were randomized to placebo and 43 to anastrozole and all received the allocated treatment. Three subjects in the placebo group and two in the anastrozole group discontinued study drug. There was no significant difference in the change in 6MWD at six months (placebo-corrected treatment effect -7.9 m, 95%CI -32.7 - 16.9, p = 0.53). There was no difference in adverse events between the groups. CONCLUSIONS: Anastrozole did not show a significant effect on 6MWD compared to placebo in post-menopausal women and men with PAH. Anastrozole was safe and did not show adverse effects. Clinical trial registration available at www. CLINICALTRIALS: gov, ID: NCT03229499.

Early goal enteral nutrition associated with decreased in-hospital death in mechanically ventilated critically ill adults: a retrospective cohort study.

INTRODUCTION: Early enteral nutrition (EN) in critically ill adult patients is thought to improve mortality and morbidity; expert guidelines recommend early initiation of EN in critically ill adults. However, the ideal schedule and dose of EN remain understudied. STUDY OBJECTIVE: Our objective was to evaluate the relationship between achieving 70% of recommended EN within 2 days of intubation ('early goal EN') and clinical outcomes in mechanically ventilated medically critically ill adults. We hypothesised that early goal EN would be associated with reduced in-hospital death. METHODS: We conducted a retrospective cohort study of mechanically ventilated adult patients admitted to our medical intensive care unit during 2013-2019. We assessed the proportion of recommended total EN provided to the patient each day following intubation until extubation, death or 7 days whichever was shortest. Patients who received 70% or more of their recommended total daily EN within 2 days of intubation (ie, 'baseline period') were considered to have achieved 'early goal EN'; these patients were compared with patients who did not ('low EN'). The primary outcome was in-hospital death; secondary outcomes were successful extubation and discharge alive. RESULTS: 938 patients met eligibility criteria and survived the baseline period. During the 7-day postintubation period, 64% of all patients reached 70% of recommended daily calories; 33% of patients achieved early goal EN. In unadjusted and adjusted models, early goal EN versus low EN was associated with a lower incidence of in-hospital death (subdistribution HR (SHR) unadjusted=0.63, p=0.0003, SHR adjusted=0.73, p=0.02). Early goal EN was also associated with a higher incidence of successful extubation (SHR unadjusted=1.41, p<0.00001, SHR adjusted=1.27, p=0.002) and discharge alive (SHR unadjusted=1.54, p<0.00001, SHR adjusted=1.24, p=0.02). CONCLUSIONS: Early goal EN was associated with significant improvement in clinical metrics of decreased in-hospital death, increased extubation and increased hospital discharge alive.

Nursing Considerations for Cytokine Release Syndrome in Relapsed/Refractory Multiple Myeloma: Experience with Teclistamab from the MajesTEC-1 Study.

OBJECTIVES: Cytokine release syndrome (CRS) is a systemic inflammatory response that is commonly observed as a class effect of T-cell-redirecting therapies. This article provides important practical guidance for nurses relating to the diagnosis, monitoring, and management of CRS in patients receiving teclistamab, based on experience from the MajesTEC-1 clinical trial and real-life nursing practice. METHODS: MajesTEC-1 is a phase 1/2 study of teclistamab in heavily pretreated patients with relapsed/refractory multiple myeloma. To mitigate the risk of high-grade CRS, patients were carefully monitored for early signs and symptoms of CRS (including fever, which must have fully resolved before teclistamab administration). RESULTS: A survey of nurses from several of the study sites provided additional real-life insights into nursing best practices for managing CRS from four academic institutions in three countries. CONCLUSIONS: In MajesTEC-1, 72% of patients treated with teclistamab experienced CRS, the majority of which was low grade. All cases resolved and none led to treatment discontinuation. Real-life supportive measures for CRS are generally aligned with those outlined in the study. IMPLICATIONS FOR NURSING PRACTICE: Because nurses are on the frontline of patient care, they play a crucial role in promptly recognizing the signs and symptoms of CRS and responding with timely and appropriate supportive treatment. This review provides important practical guidance for nurses on diagnosis, monitoring, and management of CRS in patients receiving teclistamab, based on experience from the MajesTEC-1 trial and real-life nursing practice.

Investigating peripheral blood monocyte and T-cell subsets as non-invasive biomarkers for asymptomatic hepatic steatosis: results from the Multi-Ethnic Study of Atherosclerosis.

Background: Circulating immune cells have gained interest as biomarkers of hepatic steatosis. Data on the relationships between immune cell subsets and early-stage steatosis in population-based cohorts are limited. Methods: This study included 1,944 asymptomatic participants of the Multi-Ethnic Study of Atherosclerosis (MESA) with immune cell phenotyping and computed tomography measures of liver fat. Participants with heavy alcohol use were excluded. A liver-to-spleen ratio Hounsfield units (HU) <1.0 and liver attenuation <40 HU were used to diagnose liver fat presence and >30% liver fat content, respectively. Logistic regression estimated cross-sectional associations of immune cell subsets with liver fat parameters adjusted for risk factors. We hypothesized that higher proportions of non-classical monocytes, Th1, Th17, and memory CD4+ T cells, and lower proportions of classical monocytes and naive CD4+ T cells, were associated with liver fat. Exploratory analyses evaluated additional immune cell phenotypes (n = 19). Results: None of the hypothesized cells were associated with presence of liver fat. Higher memory CD4+ T cells were associated with >30% liver fat content, but this was not significant after correction for multiple hypothesis testing (odds ratio (OR): 1.31, 95% confidence interval (CI): 1.03, 1.66). In exploratory analyses unadjusted for multiple testing, higher proportions of CD8+CD57+ T cells were associated with liver fat presence (OR: 1.21, 95% CI: 1.02, 1.44) and >30% liver fat content (OR: 1.34, 95% CI: 1.07, 1.69). Conclusions: Higher circulating memory CD4+ T cells may reflect liver fat severity. CD8+CD57+ cells were associated with liver fat presence and severity, but replication of findings is required.

Demographic and Clinical Factors Associated With SARS-CoV-2 Spike 1 Antibody Response Among Vaccinated US Adults: the C4R Study.

This study investigates correlates of anti-S1 antibody response following COVID-19 vaccination in a U.S. population-based meta-cohort of adults participating in longstanding NIH-funded cohort studies. Anti-S1 antibodies were measured from dried blood spots collected between February 2021-August 2022 using Luminex-based microsphere immunoassays. Of 6245 participants, mean age was 73 years (range, 21-100), 58% were female, and 76% were non-Hispanic White. Nearly 52% of participants received the BNT162b2 vaccine and 48% received the mRNA-1273 vaccine. Lower anti-S1 antibody levels are associated with age of 65 years or older, male sex, higher body mass index, smoking, diabetes, COPD and receipt of BNT16b2 vaccine (vs mRNA-1273). Participants with a prior infection, particularly those with a history of hospitalized illness, have higher anti-S1 antibody levels. These results suggest that adults with certain socio-demographic and clinical characteristics may have less robust antibody responses to COVID-19 vaccination and could be prioritized for more frequent re-vaccination.

Patient Priorities-Aligned Care for Older Adults With Multiple Conditions: A Nonrandomized Controlled Trial.

Importance: Older adults with multiple conditions receive health care that may be burdensome, of uncertain benefit, and not focused on what matters to them. Identifying and aligning care with patients' health priorities may improve outcomes. Objective: To assess the association of receiving patient priorities care (PPC) vs usual care (UC) with relevant clinical outcomes. Design, Setting, and Participants: In this nonrandomized controlled trial with propensity adjustment, enrollment occurred between August 21, 2020, and May 14, 2021, with follow-up continuing through February 26, 2022. Patients who were aged 65 years or older and with 3 or more chronic conditions were enrolled at 1 PPC and 1 UC site within the Cleveland Clinic primary care multisite practice. Data analysis was performed from March 2022 to August 2023. Intervention: Health professionals at the PPC site guided patients through identification of values, health outcome goals, health care preferences, and top priority (ie, health problem they most wanted to focus on because it impeded their health outcome goal). Primary clinicians followed PPC decisional strategies (eg, use patients' health priorities as focus of communication and decision-making) to decide with patients what care to stop, start, or continue. Main Outcomes and Measures: Main outcomes included perceived treatment burden, Patient-Reported Outcomes Measurement Information System (PROMIS) social roles and activities, CollaboRATE survey scores, the number of nonhealthy days (based on healthy days at home), and shared prescribing decision quality measures. Follow-up was at 9 months for patient-reported outcomes and 365 days for nonhealthy days. Results: A total of 264 individuals participated, 129 in the PPC group (mean [SD] age, 75.3 [6.1] years; 66 women [48.9%]) and 135 in the UC group (mean [SD] age, 75.6 [6.5] years; 55 women [42.6%]). Characteristics between sites were balanced after propensity score weighting. At follow-up, there was no statistically significant difference in perceived treatment burden score between groups in multivariate models (difference, -5.2 points; 95% CI, -10.9 to -0.50 points; P = .07). PPC participants were almost 2.5 times more likely than UC participants to endorse shared prescribing decision-making (adjusted odds ratio, 2.40; 95% CI, 0.90 to 6.40; P = .07), and participants in the PPC group experienced 4.6 fewer nonhealthy days (95% CI, -12.9 to -3.6 days; P = .27) compared with the UC participants. These differences were not statistically significant. CollaboRATE and PROMIS Social Roles and Activities scores were similar in the 2 groups at follow-up. Conclusions and Relevance: This nonrandomized trial of priorities-aligned care showed no benefit for social roles or CollaboRATE. While the findings for perceived treatment burden and shared prescribing decision-making were not statistically significant, point estimates for the findings suggested that PPC may hold promise for improving these outcomes. Randomized trials with larger samples are needed to determine the effectiveness of priorities-aligned care. Trial Registration: ClinicalTrials.gov Identifier: NCT04510948.

Teclistamab: Mechanism of action, clinical, and translational science.

Multiple myeloma (MM) remains incurable despite improvements in treatment options. B-cell maturation antigen (BCMA) is predominantly expressed in B-lineage cells and represents a promising new target for MM. Teclistamab (TECVAYLITM ) is the first T-cell redirecting bispecific antibody approved for patients with MM. Targeting both CD3 receptor complex on T cells and BCMA on myeloma cells, teclistamab leads to T-cell activation and subsequent lysis of BCMA+ cells. The recommended dose of teclistamab is 1.5 mg/kg subcutaneous weekly after two step-up doses of 0.06 and 0.3 mg/kg, which was selected after review of safety, efficacy, pharmacokinetic, and pharmacodynamic data. Exposure-response analyses of efficacy and safety data were also used to confirm the teclistamab dose. Teclistamab resulted in a high rate of deep and durable responses (63% overall response, 45.5% complete response or better, with 22 months median duration of response) in patients with triple-exposed relapsed/refractory MM. Common adverse reactions included cytokine release syndrome, hematologic abnormalities, and infections. Teclistamab is currently being investigated as monotherapy as well as combination therapy across different MM indications.

Aging-Related Immune Cell Phenotypes and Mortality in the Framingham Heart Study.

Background: The global increase in human life expectancy is evident. The total number of individuals aged 60 or above is anticipated to reach 2 billion by 2050. Aging, an inherently complex process, manifests prominently in the changes observed in the immune system. A notable marker of immune system aging is the presence of Aging-Related Immune Cell Phenotypes (ARIPs). Despite their significance, the connections between various ARIPs and mortality have not been thoroughly investigated. We prospectively investigated 16 different ARIPs using flow cytometry, namely, CD4/CD8 ratio, Granzyme B + CD8/Granyzme B + CD4, TN/TM = Tn / (Teff + Tem + Tcm) for TN/TM CD4 + and TN/TM CD8 + ratios, Th17/CD4 + Treg, Tc17/CD8 + Treg, Th17, Tc17, CD4 + Temra, CD8 + Temra, CD4 + CD25 + FoxP3+ (CD4 + Treg), CD8 + CD25 + FoxP3+ (CD8 + Treg) CD4 + CD27-, CD4 + CD28-CD27-, CD8 + CD27-, CD8 + CD28-CD27- and IL-6 in relation to survival outcome among dementia-free Framingham Heart Study (FHS) offspring cohort participants who attended the seventh exam (1998-2001). Results: Among 996 participants (mean age 62 years, range 40 to 88 years, 52% female), the survival rate was 65% during 19 years of follow-up. For the model adjusting for age, sex, and cytomegalovirus (CMV) serostatus, higher CD4/CD8 and Tc17/CD8 + Treg ratios were significantly associated with lower all-cause mortality (HR:0.86 [0.76-0.96], 0.84 [0.74-0.94], respectively) and higher CD8 regulatory cell levels (CD8 + CD25 + FoxP3+) were associated with higher all-cause mortality (HR = 1.17, [1.03-1.32]). Higher IL-6 levels were associated with higher all-cause, cardiovascular, and non-cardiovascular mortality (HR = 1.43 [1.26-1.62], 1.70 [1.31-2.21], and 1.36 [1.18-1.57], respectively).

Seeded stimulated X-ray emission at 5.9 keV.

X-ray free-electron lasers (XFELs) provide intense pulses that can generate stimulated X-ray emission, a phenomenon that has been observed and studied in materials ranging from neon to copper. Two schemes have been employed: amplified spontaneous emission (ASE) and seeded stimulated emission (SSE), where a second color XFEL pulse provides the seed. Both phenomena are currently explored for coherent X-ray laser sources and spectroscopy. Here, we report measurements of ASE and SSE of the 5.9 keV Mn Kα1 fluorescence line from a 3.9 molar NaMnO4 solution, pumped with 7 femtosecond FWHM XFEL pulses at 6.6 keV. We observed ASE at a pump pulse intensity of 1.7 × 1019 W/cm2, consistent with earlier findings. We observed SSE at dramatically reduced pump pulse intensities down to 1.1 × 1017 W/cm2. These intensities are well within the range of many existing XFEL instruments, which supports the experimental feasibility of SSE as a tool to generate coherent X-ray pulses, spectroscopic studies of transition metal complexes, and other applications.