The Influence of Social Determinants on Receiving Outpatient Treatment with Monoclonal Antibodies, Disease Risk, and Effectiveness for COVID-19

BACKGROUND

Limited research has studied the influence of social determinants of health (SDoH) on the receipt, disease risk, and subsequent effectiveness of neutralizing monoclonal antibodies (nMAbs) for outpatient treatment of COVID-19.

OBJECTIVE

To examine the influence of SDoH variables on receiving nMAb treatments and the risk of a poor COVID-19 outcome, as well as nMAb treatment effectiveness across SDoH subgroups.

DESIGN

Retrospective observational study utilizing electronic health record data from four health systems. SDoH variables analyzed included race, ethnicity, insurance, marital status, Area Deprivation Index, and population density.

PARTICIPANTS

COVID-19 patients who met at least one emergency use authorization criterion for nMAb treatment.

MAIN MEASURE

We used binary logistic regression to examine the influence of SDoH variables on receiving nMAb treatments and risk of a poor outcome from COVID-19 and marginal structural models to study treatment effectiveness.

RESULTS

The study population included 25,241 (15.1%) nMAb-treated and 141,942 (84.9%) non-treated patients. Black or African American patients were less likely to receive treatment than white non-Hispanic patients (adjusted odds ratio (OR) = 0.86; 95% CI = 0.82-0.91). Patients who were on Medicaid, divorced or widowed, living in rural areas, or living in areas with the highest Area Deprivation Index (most vulnerable) had lower odds of receiving nMAb treatment, but a higher risk of a poor outcome. For example, compared to patients on private insurance, Medicaid patients had 0.89 (95% CI = 0.84-0.93) times the odds of receiving nMAb treatment, but 1.18 (95% CI = 1.13-1.24) times the odds of a poor COVID-19 outcome. Age, comorbidities, and COVID-19 vaccination status had a stronger influence on risk of a poor outcome than SDoH variables. nMAb treatment benefited all SDoH subgroups with lower rates of 14-day hospitalization and 30-day mortality.

CONCLUSION

Disparities existed in receiving nMAbs within SDoH subgroups despite the benefit of treatment across subgroups.

Molecular Analysis of Clinically Defined Subsets of High-Grade Serous Ovarian Cancer

The diversity and heterogeneity within high-grade serous ovarian cancer (HGSC), which is the most lethal gynecologic malignancy, is not well understood. Here, we perform comprehensive multi-platform omics analyses, including integrated analysis, and immune monitoring on primary and metastatic sites from highly clinically annotated HGSC samples based on a laparoscopic triage algorithm from patients who underwent complete gross resection (R0) or received neoadjuvant chemotherapy (NACT) with excellent or poor response. We identify significant distinct molecular abnormalities and cellular changes and immune cell repertoire alterations between the groups, including a higher rate of NF1 copy number loss, and reduced chromothripsis-like patterns, higher levels of strong-binding neoantigens, and a higher number of infiltrated T cells in the R0 versus the NACT groups.

Abstract 5403: Reproducible elevation of RNA versus DNA mutation signal in low purity breast tumors

Background: Accurate detection of somatic mutations is critical for informing targeted therapy options. Prevalent non-cancer cell admixture complicates this detection in breast cancer. Conventional mutation detection relies on DNA sequencing; however in prior work, we demonstrated that combining RNA and DNA sequencing increases mutation signal strength, or mutant allele fraction (MAF). The ratio of RNA MAF versus DNA MAF (RNA:DNA MAF) was greatest in low purity breast tumors. We hypothesized that this elevation is biologically driven and would be conserved in a second, distinct tissue specimen of the same tumors. Here, we compare mutation characteristics between two tissue blocks in a cohort of breast tumors (n = 8) to evaluate possible preservation of RNA versus DNA mutation signal throughout the tumor.

Methods: We selected four high purity and four low purity breast tumors (“Block1”) from The Cancer Genome Atlas (TCGA) cohort and associated ABSOLUTE purity analysis. For these tumors, we acquired a second tissue block (“Block2”) not analyzed by TCGA, cut sections, analyzed sections by H&E stains, and extracted nucleic acids. Whole genome DNA sequencing and mRNA sequencing was performed for Block2 specimens using Illumina X and NextSeq 500 sequencers, respectively. Somatic mutations in Block2 were detected using UNCeqR and compared to published UNCeqR somatic mutations from TCGA. We then evaluate MAF characteristics in the entire TCGA breast tumor cohort (n = 695).

Results: Tumor purity estimates, determined by histology and by sequencing, were reduced in Block2 of the low purity tumor set versus the high purity tumor set, consistent with Block1 analysis. Molecular properties of genome-wide gene expression and somatic DNA copy number were highly similar between block-mated specimens (p < 0.01). We then identified expressed mutations present in Block1 and Block2 of the same tumor and compared the MAFs on these common mutations. DNA MAF and RNA MAF were each significantly correlated between Block1 and Block2 (p < 1e-12 in both cases). The average RNA:DNA MAF was 2.5 for the cohort, indicating that RNA mutation signal is greater than DNA in general. In Block2 specimens, the RNA:DNA MAFs were significantly greater in the low purity tumor set than the high purity tumor set (mean 2.7 versus 2.1, p < 6e-5), reflecting the same trend observed in Block1 specimens. Analyzing the entire TCGA cohort, RNA:DNA MAF was positively correlated with proliferation pathway gene expression (p < 3e-16 ) and was greatest in the Basal subtype versus other subtypes (p < 2e-9).

Conclusion: Mutant allele fraction both of DNA and of RNA was conserved across breast tumor subsections. Low purity and basal subtype breast tumors had elevated RNA:DNA MAF supporting a relationship to underlying biology and identifying classes of tumors with pronounced benefit for DNA and RNA integrated mutation analysis.

Citation Format: Jerez Te, Coralie Viollet, Xijun Zhang, Jatinder Singh, Jeffrey A. Hooke, Harvey B. Pollard, Hai Hu, Craig D. Shriver, Clifton L. Dalgard, Matthew D. Wilkerson. Reproducible elevation of RNA versus DNA mutation signal in low purity breast tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5403. doi:10.1158/1538-7445.AM2017-5403

Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.

Steric hindrance mutagenesis in the conserved extracellular vestibule impedes allosteric binding of antidepressants to the serotonin transporter

The serotonin transporter (SERT) controls synaptic serotonin levels and is the primary target for antidepressants, including selective serotonin reuptake inhibitors (e.g. (S)-citalopram) and tricyclic antidepressants (e.g. clomipramine). In addition to a high affinity binding site, SERT possesses a low affinity allosteric site for antidepressants. Binding to the allosteric site impedes dissociation of antidepressants from the high affinity site, which may enhance antidepressant efficacy. Here we employ an induced fit docking/molecular dynamics protocol to identify the residues that may be involved in the allosteric binding in the extracellular vestibule located above the central substrate binding (S1) site. Indeed, mutagenesis of selected residues in the vestibule reduces the allosteric potency of (S)-citalopram and clomipramine. The identified site is further supported by the inhibitory effects of Zn(2+) binding in an engineered site and the covalent attachment of benzocaine-methanethiosulfonate to a cysteine introduced in the extracellular vestibule. The data provide a mechanistic explanation for the allosteric action of antidepressants at SERT and suggest that the role of the vestibule is evolutionarily conserved among neurotransmitter:sodium symporter proteins as a binding pocket for small molecule ligands.

Induction of basic fibroblast growth factor (bFGF) expression following focal cerebral ischemia

Basic fibroblast growth factor (bFGF) is a biologically active polypeptide with mitogenic, angiogenic, and neurotrophic properties. In the present study, we examined the temporal and spatial expression profiles of bFGF mRNA and protein concentration in a focal cerebral ischemia model induced by transient occlusion of the right middle cerebral artery (MCA) and both common carotid arteries (CCAs). Results of Northern blot analysis shows a transient 2.5-fold increase in the 6.0 kb transcript of bFGF mRNA within the ischemic cortex of rats subjected to 60 min ischemic insult followed by 12 h of reperfusion. Although enhanced expression of bFGF mRNA was also noted in the ipsilateral hippocampus, the temporal induction profile appeared to be different from that of the ischemic cortex. A significant increase in bFGF mRNA was observed as early as 60 min following ischemia and remained elevated for up to 2 weeks after the onset of reperfusion. In situ hybridization studies revealed constitutive expression of bFGF mRNA in discrete brain regions of sham-operated animals. Following 60 min ischemia and 12 h reperfusion, increased expression of bFGF mRNA was observed in the ischemic cortex (both peri-infarct and infarct area). Increased expression of bFGF mRNA within the infarcted area is largely confined rostrally to the outer cortical layers of the infarct, an area with increased density of blood vessels. bFGF-like immunoreactivity was also detected in areas expressing bFGF mRNA. Furthermore, a striking increase in bFGF-like immunoreactivity was observed in the ipsilateral hippocampus. Double-staining with anti-GFAP antibody indicated that the majority of the bFGF-like immunoreactivity was localized in the astrocytes, however, not all astrocytes showed bFGF-like immunoreactivity. Some GFAP negative cell also showed bFGF-like immunoreactivity. In summary, increased expression of both bFGF mRNA and immunoreactivity following ischemia were located in the same brain regions. An increase in bFGF-like immunoreactivity after ischemic insult is likely due to an increase in the expression of its 6.0 kb bFGF mRNA transcripts. Although increased bFGF mRNA was observed in both ischemic cortex and ipsilateral hippocampus after ischemic insult, the temporal expression profiles differed. Results from the present study raise the possibility that increased expression of bFGF in the peri-infarcted area may limit the spread of ischemic injury.

Prolongation and enhancement of postischemic c-fos expression after fasting

BACKGROUND AND PURPOSE

A rapid but transient expression of c-fos after cerebral ischemia has been extensively documented. However, the mechanism of this induction and whether induction of c-fos is neuroprotective or detrimental to the brain after ischemia is presently not clear. Fasting before transient cerebral ischemia has been shown to reduce delayed neuronal necrosis and infarct volume. The purpose of the present study was to examine the effect of preischemic fasting for 24 hours on the expression of c-fos after transient focal cerebral ischemia.

METHODS

Focal cerebral ischemia was induced by temporary occlusion of the right middle cerebral artery and both common carotid arteries for 60 minutes. Male Long-Evans rats weighting 250 to 300 g were randomly divided into two groups: fed (control group) and food deprived for 24 hours (fasted group) before ischemic surgery. Infarct volumes were measured on the basis of triphenyltetrazolium chloride-delineated infarct areas, and plasma glucose levels were determined by the glucose oxidase method. Temporal and spatial expression of c-fos was assessed by Northern blot analysis, in situ hybridization, and immunohistochemistry.

RESULTS

Fasting for 24 hours before 60 minutes of ischemia resulted in a 26.6% decrease in preischemic plasma glucose levels and a 74.5% reduction in infarct volumes in the fasted group compared with the control group. A rapid but transient induction of c-fos mRNA was observed in the ischemic cortex in control animals after 60 minutes of ischemia. Fasting not only prolonged but also enhanced the intensity of c-fos expression in the ischemic cortex. Regional c-fos expression was also different between these two groups.

CONCLUSIONS

The results support the contention that c-fos expression may be compatible with its purported neuroprotective role in selected experimental paradigms. The signaling mechanisms underlying the effect of fasting and subsequent lowering of plasma glucose levels on postischemic c-fos expression remain to be explored.