Single-cell RNA sequencing and spatial transcriptomics reveal cancer-associated fibroblasts in glioblastoma with protumoral effects

Cancer-associated fibroblasts (CAFs) were presumed absent in glioblastoma given the lack of brain fibroblasts. Serial trypsinization of glioblastoma specimens yielded cells with CAF morphology and single-cell transcriptomic profiles based on their lack of copy number variations (CNVs) and elevated individual cell CAF probability scores derived from the expression of 9 CAF markers and absence of 5 markers from non-CAF stromal cells sharing features with CAFs. Cells without CNVs and with high CAF probability scores were identified in single-cell RNA-Seq of 12 patient glioblastomas. Pseudotime reconstruction revealed that immature CAFs evolved into subtypes, with mature CAFs expressing actin alpha 2, smooth muscle (ACTA2). Spatial transcriptomics from 16 patient glioblastomas confirmed CAF proximity to mesenchymal glioblastoma stem cells (GSCs), endothelial cells, and M2 macrophages. CAFs were chemotactically attracted to GSCs, and CAFs enriched GSCs. We created a resource of inferred crosstalk by mapping expression of receptors to their cognate ligands, identifying PDGF and TGF-β as mediators of GSC effects on CAFs and osteopontin and HGF as mediators of CAF-induced GSC enrichment. CAFs induced M2 macrophage polarization by producing the extra domain A (EDA) fibronectin variant that binds macrophage TLR4. Supplementing GSC-derived xenografts with CAFs enhanced in vivo tumor growth. These findings are among the first to identify glioblastoma CAFs and their GSC interactions, making them an intriguing target.

Abstract LB054: Confirmation of target inhibition and anti-tumor activity of the SHP2 inhibitor RMC-4630 via longitudinal analysis of ctDNA in a phase 1 clinical study

RMC-4630 is a potent, selective, orally bioavailable allosteric inhibitor of SHP2, a central node in the RAS signaling pathway. Preclinical data have demonstrated that RMC-4630 can shrink tumors carrying certain mutations in the RAS pathway such as KRASG12C, NF1LOF, and BRAFClass3. Longitudinal circulating tumor DNA (ctDNA) was isolated from blood using GuardantOMNI in 80 patients with relapsed/refractory solid tumors in the phase 1 dose-escalation trial of RMC-4630 (NCT03634982) to characterize and confirm RAS pathway mutations and to evaluate molecular responses in patients receiving RMC-4630 monotherapy. Safety, PK and efficacy findings from this study are reported in a separate abstract. 78 of 80 patients had baseline somatic mutations detected in plasma, of which 60 were either KRASG12X, NF1LOF, or BRAFClass3; 48 of these 60 patients also had on-treatment ctDNA assessments and these patients constitute the population reported here. 9 of 48 patients (19%) had KRASG12C detected at baseline, available scan results and a ctDNA sample after 4 weeks of receiving RMC-4630. A decrease in KRASG12C variant allele frequency (VAF) was detected in 5/9 patients (56%) with clearance in 1 patient with a partial response. Decrease in KRASG12C VAF was associated with change in tumor volume (PCC=0.85, p=0.008), preceding scan results by approximately 1 month, suggesting that change in KRASG12C VAF may be an early measure of drug activity or possibly response. 5 of 48 patients (10%) had NF1LOF detected at baseline. A decrease, or stability in NF1LOF VAF on treatment compared to baseline was detected in 4 (80% of all NF1LOF patients). The decrease in NF1LOF VAF was not associated with change in tumor volume and may represent effects of RMC-4630 on a subclone harboring NF1LOF. One patient had a detectable BRAFClass3 mutation at baseline, which decreased in VAF on treatment compared to baseline. Of the remaining patients there were 12 KRASG12D, 9 KRASG12V and other KRASG12X. The majority progressed with an increase in VAF of all mutations including KRASG12X, suggesting that the KRASG12X-containing clone is responsible for escape from single agent RMC-4630. In most instances the increase in KRASG12X VAF in blood preceded determination of clinical progression. Longitudinal assessment of ctDNA indicates that some patients with RAS-addicted tumors undergo a molecular response on treatment with the SHP2 inhibitor RMC-4630.

Citation Format: Josie L. Hayes, Marianna Koczywas, Sai-Hong Ignatius Ou, Pasi A. Janne, Jose M. Pacheco, Susanna Ulahannan, Judy S. Wang, Howard A. Burris, Jonathan W. Riess, Caroline McCoach, Michael S. Gordon, Anna Capasso, Ariel Chen, Richa Dua, Bojena Bitman, Martha Guerra, Hongfang Wang, Xiaolin Wang, Eric Haura. Confirmation of target inhibition and anti-tumor activity of the SHP2 inhibitor RMC-4630 via longitudinal analysis of ctDNA in a phase 1 clinical study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB054.

Proteomic Analysis Implicates Vimentin in Glioblastoma Cell Migration

We previously showed lithium chloride (LiCl) and other inhibitors of glycogen synthase kinase-3 (GSK-3) including 6-bromo-indirubin-3-oxime (BIO), can block glioblastoma (GBM) cell migration. To investigate the mechanisms involved we used two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry to identify proteins altered after treatment of U251 GBM cells with 20 mM LiCl. Downregulation of the intermediate filament protein vimentin was the most significant change identified. Analysis of patient tumor samples revealed that vimentin is expressed abundantly in GBM, and is prognostic especially in lower grade tumors. Additionally, siRNA-mediated vimentin knockdown impaired GBM migration. Western blotting showed that treatment with LiCl or small molecule GSK-3 inhibitors led to the rapid downregulation of detergent soluble vimentin levels across a panel of GBM-derived cells. Fluorescence reactivation after photobleaching (FRAP) microscopy studies showed a significant reduction in the ability of the vimentin cytoskeleton to recover from photo-bleaching in the presence of LiCl or BIO. Biochemical studies revealed that GSK-3 and vimentin directly interact, and analysis of vimentin revealed a GSK-3 consensus phosphorylation site. We conclude that anti-migratory compounds with the ability to inhibit GSK-3 have effects on vimentin cytoskeletal dynamics, which may play a role in their anti-invasive activity.

Disruption of the β1L Isoform of GABP Reverses Glioblastoma Replicative Immortality in a TERT Promoter Mutation-Dependent Manner

TERT promoter mutations reactivate telomerase, allowing for indefinite telomere maintenance and enabling cellular immortalization. These mutations specifically recruit the multimeric ETS factor GABP, which can form two functionally independent transcription factor species: a dimer or a tetramer. We show that genetic disruption of GABPβ1L (β1L), a tetramer-forming isoform of GABP that is dispensable for normal development, results in TERT silencing in a TERT promoter mutation-dependent manner. Reducing TERT expression by disrupting β1L culminates in telomere loss and cell death exclusively in TERT promoter mutant cells. Orthotopic xenografting of β1L-reduced, TERT promoter mutant glioblastoma cells rendered lower tumor burden and longer overall survival in mice. These results highlight the critical role of GABPβ1L in enabling immortality in TERT promoter mutant glioblastoma.

Immune evasion mediated by PD-L1 on glioblastoma-derived extracellular vesicles

Binding of programmed death ligand-1 (PD-L1) to programmed cell death protein-1 (PD1) leads to cancer immune evasion via inhibition of T cell function. One of the defining characteristics of glioblastoma, a universally fatal brain cancer, is its profound local and systemic immunosuppression. Glioblastoma has also been shown to generate extracellular vesicles (EVs), which may play an important role in tumor progression. We thus hypothesized that glioblastoma EVs may be important mediators of immunosuppression and that PD-L1 could play a role. We show that glioblastoma EVs block T cell activation and proliferation in response to T cell receptor stimulation. PD-L1 was expressed on the surface of some, but not of all, glioblastoma-derived EVs, with the potential to directly bind to PD1. An anti-PD1 receptor blocking antibody significantly reversed the EV-mediated blockade of T cell activation but only when PD-L1 was present on EVs. When glioblastoma PD-L1 was up-regulated by IFN-γ, EVs also showed some PD-L1-dependent inhibition of T cell activation. PD-L1 expression correlated with the mesenchymal transcriptome profile and was anatomically localized in the perinecrotic and pseudopalisading niche of human glioblastoma specimens. PD-L1 DNA was present in circulating EVs from glioblastoma patients where it correlated with tumor volumes of up to 60 cm³. These results suggest that PD-L1 on EVs may be another mechanism for glioblastoma to suppress antitumor immunity and support the potential of EVs as biomarkers in tumor patients.

Repellent properties of the host compound 4-allylanisole to the southern pine beetle

The phenylpropanoid 4-allylanisole is a compound produced by loblolly pines (Pinus taeda L.), an abundant species in southern pine forests and a preferred host of southern pine beetle (Dendroctonus frontalis Zimmermann). Repellency of individual beetles was demonstrated in laboratory behavioral assays ofD. frontalis and other scolytids. Inhibition was demonstrated in natural populations ofD. frontalis using baited traps. In both tests, response to the inhibitory pheromone verbenone was used for comparison. In the laboratory, a higher proportion of newly emerged and reemergedD. frontalis responded negatively to 4-allylanisole than to verbenone. However, fewer reemergent than newly emerged individuals responded to either compound. In all field trials, the response ofD. frontalis to its attractant pheromone in funnel traps was significantly reduced by simultaneous release of 4-allylanisole. In most trials total reduction did not differ from verbenone; however, unlike verbenone, 4-allylanisole reduced male and female catches proportionally. Both compounds together did not significantly further reduce trap catch. The response of a major predator,Thanasimus dubius (F.), to the attractant pheromone ofD. frontalis, did not differ with the simultaneous release of either verbenone or 4-allylanisole. The results of preliminary field applications are presented and discussed.

The use of local anaesthesia in haemorrhoidal banding: a randomized controlled trial

AIM

Rubber band ligation is a common office procedure for the treatment of symptomatic haemorrhoids. It can be associated with pain and vasovagal symptoms. The effect of local anaesthetic use during banding was studied.

METHOD

A single-blinded randomized controlled trial was carried out in the colorectal outpatient clinic. Patients presenting with symptomatic haemorrhoids suitable for banding were prospectively recruited and randomized to undergo the procedure with local anaesthetic or without (control). Submucosal bupivacaine was injected immediately after banding just proximal to the site. Vasovagal symptoms were assessed at the time of banding and pain scores (visual analogue scale) were recorded at the conclusion of the procedure, after 15 min, and on leaving the clinic.

RESULTS

Seventy-two patients (40 local anaesthetic injection, group 1; 32 no injection, group 2) were recruited. The mean ages were 50 and 54 years respectively, the median duration of symptoms was 12 months in each group and the median number of haemorrhoids banded was three in each group. The mean pain score on leaving the clinic was 2.6 (95% CI 2.1, 3.1) in group 1 and 4.1 (95% CI 3.3, 5.0) (P = 0.04) in group 2. There were no complications related to local anaesthetic use. No significant difference in vasovagal symptoms was found (P = 0.832).

CONCLUSION

Local anaesthetic injection at the time of banding is simple and safe. It may reduce patient discomfort following banding of haemorrhoids.

Surgical versus medical methods for second trimester induced abortion

BACKGROUND

Determining the optimal method of performing second-trimester abortions is important, since they account for a disproportionate amount of abortion-related morbidity and mortality.

OBJECTIVES

To compare surgical and medical methods of inducing abortion in the second trimester of pregnancy with regard to efficacy, side effects, adverse events, and acceptability.

SEARCH STRATEGY

We identified trials using Pub Med, EMBASE, POPLINE, and the Cochrane Central Register of Controlled Trials (CENTRAL). We also searched the reference lists of identified studies, relevant review articles, book chapters, and conference proceedings for additional, previously unidentified studies. We contacted experts in the field for information on other published or unpublished research.

SELECTION CRITERIA

Randomised trials comparing any surgical to any medical method of inducing abortion at >/= 13 weeks' gestation were included.

DATA COLLECTION AND ANALYSIS

We assessed the validity of each study using the methods suggested in the Cochrane Handbook. Investigators were contacted as needed to provide additional information regarding trial conduct or outcomes. Two reviewers abstracted the data. Odds ratios and 95% confidence intervals were calculated for dichotomous variables using RevMan 4.2. The trials did not have uniform interventions, therefore, we were unable to combine them into a meta-analysis.

MAIN RESULTS

Two studies met criteria for this review. One compared dilation and evacuation (D&E) to intra-amniotic instillation of prostaglandin F(2) (alpha). The second study compared D&E to induction with mifepristone and misoprostol. Compared with prostaglandin instillation, the combined incidence of minor complications was lower with D&E (OR 0.17, 95% CI 0.04-0.65) as was the total number of minor and major complications (OR 0.12, 95% CI 0.03-0.46). The number of women experiencing adverse events was also lower with D&E than with mifepristone and misoprostol (OR 0.06, 95% CI 0.01-0.76). Although women treated with mifepristone and misoprostol reported significantly more pain than those undergoing D&E, efficacy and acceptability were the same in both groups. In both trials, fewer subjects randomised to D&E required overnight hospitalisation.

AUTHORS' CONCLUSIONS

Dilation and evacuation is superior to instillation of prostaglandin F(2) (alpha). The current evidence also appears to favour D&E over mifepristone and misoprostol, however larger randomised trials are needed.

Candesartan cilexetil: comparison of once-daily versus twice-daily administration for systemic hypertension. Candesartan Cilexetil Study Investigators

This randomized, double-masked, placebo-controlled, forced-titration, parallel-arm study was designed to compare the blood pressure (BP)-lowering effect of candesartan cilexetil, a potent antagonist of the angiotensin II receptor subtype AT1, administered once daily with that of the same agent administered twice daily at the same total daily dose of 16 mg. After a 4- to 5-week placebo run-in period, 277 patients with a sitting diastolic BP of 95 to 109 mm Hg were randomly allocated to receive placebo (n = 92) or candesartan cilexetil 8 mg once daily for 4 weeks, followed by forced titration to either 16 mg once daily (n = 91) or 8 mg twice daily (n = 94) for 4 weeks. At 8 weeks, mean reductions in trough sitting diastolic BP were similar for the once- and twice-daily treatment groups (9.4 and 10.3 mm Hg, respectively). After 8 weeks of treatment, no statistically significant differences were observed in diastolic or systolic BP, peak or trough BP, or sitting or standing BP between the 2 active-treatment groups. The rates of positive responses (defined as a trough sitting diastolic BP of <90 mm Hg or a decrease in BP of > or =10 mm Hg) were also similar (approximately 60%) in the once- and twice-daily candesartan cilexetil groups. Furthermore, placebo-corrected trough-to-peak ratios for sitting diastolic BP exceeded 75% for both candesartan cilexetil regimens, indicating a persistent 24-hour duration of drug effect. Ambulatory BP monitoring performed in a subset of patients (n = 44) confirmed the consistent 24-hour BP-lowering effect and preservation of diurnal variation with once-daily dosing. No significant between-group differences were observed in the incidence or severity of clinical or laboratory adverse events. The results of this study suggest that identical daily doses of candesartan cilexetil administered once or twice daily have comparable efficacy and tolerability and that no additional clinical benefit is derived from twice-daily administration.

Genetic relatedness of North American populations of Tomicus piniperda (Coleoptera:Scolytidae)

We used DNA fingerprinting by random amplified polymorphic (RAPD) DNA and electrophoretic characterization of esterase isozymes to investigate the genetic relatedness of North American populations of the exotic bark beetle Tomicus piniperda (L.). Cluster analyses of genetic distances among populations identified the Illinois population as an outlier population with mean genetic distances to other populations averaging 0.895 (where complete dissimilarity = 2), compared with genetic distance averages of 0.595 among populations excluding Illinois. When genetic distance means and geographical distance between populations were compared, the results suggested that T. piniperda populations in the United States were established separately in Illinois near Lake Michigan and in Ohio along Lake Erie. Molecular markers indicated that insects derived from the 2 founder groups were interbreeding in contiguous regions in western Indiana.

Encapsulated cell technology

The potential therapeutic applications of encapsulated cells are enormous. In the US alone, it has been estimated that nearly half-a-trillion dollars are spent each year to care for patients who suffer tissue loss or dysfunction. Over 6 million patients suffer from neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, over 14 million patients suffer from diabetes, and millions more from liver failure, hemophilia, and other diseases caused by the loss of specific vital cellular functions. It appears likely that by the end of the decade clinical trials of encapsulated cells to treat many of these diseases will become a reality. The Food and Drug Administration has already authorized studies to evaluate the safety and biological activity of several types of systems. A number of issues will have to be addressed, including the sourcing of raw materials, the design and building of manufacturing facilities, the scale-up and optimization process, storage and distribution of the product, and quality control.

Potentially hazardous co-prescribing of beta-adrenoceptor antagonists and agonists in the community

AIM

The aim of this study was to investigate the co-prescribing of beta-antagonists and beta-agonists in the community, and to assess the potential hazards of such co-prescribing.

METHODS

The study was set in the population of Tayside, Scotland (population approximately 400,000), between January 1993 and March 1993. An automated person-specific prescribing database was used, which could also be linked to hospital admissions. Patients who were co-prescribed beta-antagonists and beta-agonists on the same day or within 30 days were selected. A model was used to identify those who showed an asthmatic profile, on the basis of age, and previous prescribing and hospitalization history, and for whom the co-prescribing was judged to be particularly hazardous.

RESULTS

Altogether, 0.9% of 15824 patients who received a beta-antagonist during the study period received a beta-agonist on the same day. This figure increased to 274 (1.7%) for 30-day co-prescription. A few instances of particularly hazardous co-prescribing were identified, which involved young people who had previously received prescriptions for corticosteroids and been hospitalized for asthma.

CONCLUSION

Potentially hazardous co-prescribing of beta-agonists and beta-antagonists occurs despite labelled warnings, even in patients who appear to be at high risk. These events are quite rare but probably should not occur at all.

Factors associated with failure to complete treatment for diabetic retinopathy among Navajo Indians

OBJECTIVE

To determine the proportion of patients with suspected proliferative diabetic retinopathy who did not receive the recommended follow-up ophthalmological evaluation and care, and to examine associations between various patient characteristics and the failure to obtain care.

RESEARCH DESIGN AND METHODS

The study cohort included all Navajo Indians identified by a retrospective review of records who had proliferative diabetic retinopathy diagnosed at an Indian Health Service Optometry Clinic between 1 October 1985 and 30 September 1988. Follow-up data were obtained by medical record reviews and by interviews with subjects.

RESULTS

Of 69 patients identified, 57 of 61 living patients were interviewed. Twenty-three (40.4%) had failed to obtain recommended follow-up. The RR for incomplete treatment among those without a vehicle in the household compared with those with a vehicle was 1.91 (95% CI 1.32-2.76). Other factors associated with incomplete treatment were female sex and marital status other than currently married. Twelve (21%) patients answered "no" to the question, "Have you been told that diabetes was affecting your eyes?" Eight of 38 (21%) who confirmed that they had been told that diabetes was affecting their eyes responded "no" to the question, "Do you think that diabetes is affecting your eyes?" However, the answers to these questions did not distinguish between patients who obtained or did not obtain recommended care.

CONCLUSIONS

Interventions to increase the proportion of Navajo Indians with diabetic retinopathy who receive appropriate ophthalmologic care must address the issue of transportation.