3D models of glioblastoma interaction with cortical cells

Introduction: Glioblastoma (GBM) invasiveness and ability to infiltrate deep into the brain tissue is a major reason for the poor patient prognosis for this type of brain cancer. Behavior of glioblastoma cells, including their motility, and expression of invasion-promoting genes such as matrix metalloprotease-2 (MMP2), are strongly influenced by normal cells found in the brain parenchyma. Cells such as neurons may also be influenced by the tumor, as many glioblastoma patients develop epilepsy. In vitro models of glioblastoma invasiveness are used to supplement animal models in a search for better treatments, and need to combine capability for high-throughput experiments with capturing bidirectional interactions between GBM and brain cells.

Methods: In this work, two 3D in vitro models of GBM-cortical interactions were investigated. A matrix-free model was created by co-culturing GBM and cortical spheroids, and a matrix-based model was created by embedding cortical cells and a GBM spheroid in Matrigel.

Results: Rapid GBM invasion occurred in the matrix-based model, and was enhanced by the presence of cortical cells. Little invasion occurred in the matrix-free model. In both types of models, presence of GBM cells resulted in a significant increase in paroxysmal neuronal activity.

Discussion: Matrix-based model may be better suited for studying GBM invasion in an environment that includes cortical cells, while matrix-free model may be useful in investigation of tumor-associated epilepsy.

Efficacy of Radial Endobronchial Ultrasound (R-EBUS) guided transbronchial cryobiopsy for peripheral pulmonary lesions (PPL...s): A systematic review and meta-analysis

BACKGROUND

Transbronchial lung cryobiopsy (TBLC) is frequently described for the diagnosis of diffuse parenchymal lung diseases (DPLD). A few studies have reported transbronchial cryobiopsy for the diagnosis of peripheral pulmonary lesions (PPL...s). We aimed to study the utility and safety of transbronchial cryobiopsy for the diagnosis of PPL...s.

METHODS

We performed a systematic search of the PubMed and Embase databases to extract the relevant studies. We then performed a meta-analysis to calculate the diagnostic yields of transbronchial cryobiopsy and bronchoscopic forceps biopsy.

RESULTS

Following a systematic search, we identified nine relevant studies (300 patients undergoing cryobiopsy). All used Radial Endobronchial Ultrasound (R-EBUS) for PPL localization. The pooled diagnostic yield of transbronchial cryobiopsy was 77% (95% CI, 71%...84%) (I^2=38.72%, p=0.11). The diagnostic yield of forceps biopsy was 72% (95% CI, 60%...83%) (I^2=78.56%, p<0.01). The diagnostic yield of cryobiopsy and forceps biopsy was similar (RR 1.05, 95% CI 0.96...1.15), with a 5% risk difference for diagnostic yield (95% CI, ...6% to 15%). There was significant heterogeneity (I^2=57.2%, p=0.017), and no significant publication bias. One severe bleeding and three pneumothoraxes requiring intercostal drain (ICD) placement (major complication rate 4/122, 1.8%) were reported with transbronchial cryobiopsy.

CONCLUSIONS

R-EBUS guided transbronchial cryobiopsy is a safe and efficacious modality. The diagnostic yields of TBLC and forceps biopsy are similar. More extensive multicentre randomized trials are required for the further evaluation and standardization of transbronchial cryobiopsy for PPL...s.

Mental health, economic well-being and health care access amid the COVID-19 pandemic: a mixed methods study among urban men who have sex with men in India

Scant empirical research from Asia has addressed the impact of COVID-19 on sexual minority health. We aimed to explore and understand the impact of COVID-19 on income security, mental health, HIV risk and access to health services among men who have sex with men (MSM) in India. We conducted a concurrent mixed methods study from April to June 2020, including a cross-sectional survey and in-depth semi-structured interviews with MSM recruited from three non-governmental organisations providing HIV prevention services in Chandigarh, India. We examined the associations of sexual minority stressors (sexual stigma, internalised homonegativity), economic stressors, and stress due to social distancing, with depression and anxiety, HIV risk, and access to health services. Survey findings (n = 132) indicated that internalised homonegativity and stress related to social distancing were significantly associated with depressive and anxiety symptoms. Results also showed reduced access to condoms, HIV testing and counselling services. Qualitative findings (n = 10) highlighted adverse economic impacts of COVID-19, including loss of employment/wages and engaging in survival sex work, which contributed to psychological distress and HIV risk. The COVID-19 pandemic has resulted in considerable psychological and financial distress among low socioeconomic status MSM in India, including those involved in sex work - communities already marginalised in economic, family and healthcare sectors. Structural interventions to improve access to mental health and HIV services and decrease financial burden are critical to mitigate the impact of COVID-19.

Absence of atrial fibrillation in the blanking period following cryoballoon pulmonary vein isolation – does it always portend a good prognosis?

Background

Cryoballoon (CB) pulmonary vein isolation (PVI) is an accepted method for ablation in patients with paroxysmal and persistent atrial fibrillation (PAF, PeAF). Freedom from AF in the blanking period (BP), conventionally defined as the first 3-months post-PVI, has been associated with the best long-term outcomes. However, the influence of antiarrhythmic drugs (AADs) during the BP on long-term outcomes is not well understood.

Objective

To compare long-term outcomes between patients who were and were not on an AAD prior to ablation and remained free from AF during the 3-month BP post CB PVI.

Methods

We enrolled consecutive AF patients undergoing CB PVI; all pts had an implantable loop recorder (ILR). No patient had any AF in the first 90 days post CB PVI. We divided the patients into three groups: (1) never had exposure to an AAD; (2) were intolerant to/failed AAD and thus were not taking an AAD at time of ablation; and (3) were on AAD at time of ablation. In the latter group, every effort was made to stop the AAD before the end of the BP.

Results

The cohort included 96 pts (66±10 years; 60 [63%] male; 55 [57%] PAF; CHA2DS2-VASc 2.5±1.4). There were 23 (24%) patients in group 1, 13 (14%) patients in group 2, and 60 (63%) pts in group 3. Patients in group 3 were more likely to have PeAF; AADs were stopped at a median of 36 days IQR (27, 91) in this group. Patients were followed for 1-year during which time 28 (29%) patients had recurrent AF (despite having no AF during the BP). The best outcome was seen in patients who never used an AAD; the worst outcome was seen in patients who were on an AAD at time of ablation (Figure 1).

Conclusion

Our data show that absence of AF during a 3-month post CB PVI BP alone does not guarantee good-long term outcome, unless the patient was never treated with an AAD. In contrast, in patients ablated while taking an AAD, recurrent AF was observed in 37% even though they were completely AF-free during the BP.

Funding Acknowledgement

Type of funding sources: None.

Recurrence of atrial fibrillation following pulmonary vein isolation: impact of body mass index on one- and three-year outcomes

Background

Cryoballoon (CB) pulmonary vein isolation (PVI) is an accepted method for ablation in patients with paroxysmal and persistent atrial fibrillation (PAF, PeAF). However, there are a paucity of data about the impact of body mass index (BMI) on one-year and longer-term outcomes following ablation.

Objective

To objectively understand the impact of BMI on outcomes following CB PVI.

Methods

We enrolled consecutive AF patients undergoing CB PVI; all patients had an implantable loop recorder (ILR), which transmitted data wirelessly daily. We assessed AF recurrences after excluding an initial 3-month post-ablation blanking period.

Results

The cohort included 222 pts (66±9 years; 143 [64%] male; 120 [54%] PAF; CHA2DS2-VASc 2.6±1.6). The mean BMI was 30±5. Patients were followed for 763±347 days, during which time 50% and 68% had recurrent AF 1- and 3-years post ablation. We divided the cohort based on the mean BMI into 2 groups: BMI &lt;30 and BMI &gt;30. Heavier patients were younger and more likely to have PeAF. Over 1-year of follow-up, patients with a BMI &lt;30 had similar likelihood of being free of AF to patients with a BMI &gt;30 (46% vs, 56%, p=0.0.097, Figure 1, left). However, as patients were followed for 3-years, freedom from AF was significantly higher in patients with a BMI &lt;30 (59% vs. 81% in BMI &gt;30, p=0.002, Figure 1, right).

Conclusions

Our data show that although patients had similar outcomes 1-year post-ablation, during longer-term follow-up patients with a BMI &gt;30 had a much worse outcome. Our study uniquely offers objective (using an ILR) assessment of the impact of BMI on long-term outcomes following CB PVI (homogenous ablation strategy). These data highlight the need to identify strategies to improve outcomes in obese patients.

Funding Acknowledgement

Type of funding sources: None.

Superconducting-qubit readout via low-backaction electro-optic transduction

Entangling microwave-frequency superconducting quantum processors through optical light at ambient temperature would enable means of secure communication and distributed quantum information processing¹. However, transducing quantum signals between these disparate regimes of the electro-magnetic spectrum remains an outstanding goal^2-9, and interfacing superconducting qubits, which are constrained to operate at millikelvin temperatures, with electro-optic transducers presents considerable challenges owing to the deleterious effects of optical photons on superconductors^9,10. Moreover, many remote entanglement protocols^11-14 require multiple qubit gates both preceding and following the upconversion of the quantum state, and thus an ideal transducer should impart minimal backaction¹⁵ on the qubit. Here we demonstrate readout of a superconducting transmon qubit through a low-backaction electro-optomechanical transducer. The modular nature of the transducer and circuit quantum electrodynamics system used in this work enable complete isolation of the qubit from optical photons, and the backaction on the qubit from the transducer is less than that imparted by thermal radiation from the environment. Moderate improvements in the transducer bandwidth and the added noise will enable us to leverage the full suite of tools available in circuit quantum electrodynamics to demonstrate transduction of non-classical signals from a superconducting qubit to the optical domain.

The impact of atrial fibrillation burden early post cryoballoon pulmonary vein isolation on long-term freedom from recurrent atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. A three-month blanking period (BP) is commonly used in clinical trials and practice. Early recurrence of AF portends worse ablation long-term outcome; however, the utility of using AF burden (AFB) early post cryoballoon (CB) PVI to predict long-term outcome is unknown.

Purpose

To determine, using ECG data acquired by an implantable loop recorder (ILR), the relationship between post-ablation AFB and long-term freedom from AF.

Methods

We enrolled consecutive patients with AF who had CB PVI and an ILR. We determined the monthly AFB for the first 3 months post CB PVI and assessed the relationship between AFB and 1-year freedom from AF. We defined 4 distinct AFB groups: (1) 0%, (2) &gt; 0-0.1%, (3) &gt; 0.1-0.5%, and (4) &gt; 0.5%.

Results

There were 210 patients (66 ± 9 years; 138 [66%] male; 116 [55%] paroxysmal AF; CHA2DS2-VASc 2.5 ± 1.6). Following a 3-month BP, 101 (48%) patients had a recurrence of AF at 160 ± 86 days post-ablation. An AFB of &gt; 0% over the first 3 months predicted AF recurrence (p &lt; 0.0001, Figure 1). Patients with &gt; 0.5% AF burden after 1st month and any AF after 2nd month post CB PVI have a very high long-term AF recurrence rate (Figure 2).

Conclusion

The best long term outcome post CB PVI is seen in pts who have no AF in the first 3 months post ablation. An AFB &gt;0.5% after the first month and any AF after the second month portend ablation failure. These data define a clinical utility of using AFB to risk stratify patients post CB PVI.

Yearly incidence and pattern of very late recurrence of atrial fibrillation as detected by continuous electrocardiographic monitoring using an implantable loop recorder

Funding Acknowledgements

Type of funding sources: None.

Background

A very late recurrence (VLR) of atrial fibrillation (AF) is considered present when patients have their first recurrence of AF &gt; 12 months post-ablation. Little is known about the yearly rates and patterns of VLR AF recurrence.

Objective

To assess the yearly incidence and pattern of VLR in pts with AF who underwent cryoballoon (CB) pulmonary vein isolation (PVI).

Methods

We prospectively enrolled consecutive patients with AF who underwent CB PVI and had an implantable loop recorder (ILR) inserted up to 3 months post-ablation. Patients were followed for recurrent AF (excluding a 3-month post-ablation blanking period).

Results

Our cohort included 222 patients (66 ± 9 years; 143 [64%] male; 120 [54%] paroxysmal AF; CHA2DS2-VASc 2.6 ± 1.6). At 1-year, 111 (50%) patients remained free of AF. Two-year follow-up was available in 95 of these patients; 62 (65%) remained in sinus. Three-year follow-up was available in 42 of these patients; 36 (86%) remained in sinus (Figure). Of the 39 patients who developed AF after initially being free of AF for at least 1-year post ablation, 24 (62%) patients had either a frequent or persistent pattern of AF.

Conclusions

Our data show that the greatest likelihood of failure following a CB PVI occurs in the first year of ablation. The rate of failure becomes lower year by year. These data suggest that long term outcome may be driven more by the initial ablation as opposed to progressive evolution of the patient’s substrate

Risk factors of mortality after secondary procedures during the world-wide randomized antibiotic envelope infection prevention trial (WRAP-IT)

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Medtronic

Background

Previous analysis of WRAP-IT (World-wide Randomized Antibiotic Envelope Infection Prevention trial) data identified both patient and procedural characteristics as risk factors for cardiac implantable electronic device (CIED) infection. In the current analysis, we sought to similarly use prospectively collected WRAP-IT data to assess risk factors of all-cause mortality. Understanding if mortality risk can be modified and identifying baseline characteristics associated with high risk can help guide physician decision making.

Purpose

To identify modifiable and non-modifiable risk factors for 1-year all-cause mortality after a secondary (replacement, revision, or upgrade) CIED procedure.

Methods

This analysis included 5,461 secondary procedure patients from the WRAP-IT study. Included as candidate factors were patient and procedural characteristics. Patients with more than one year follow-up were censored at one year. A multivariate Cox Proportional Hazards model was reached by stepwise selection to minimize Akaike Information Criterion.

Results

The overall one-year mortality rate was 5.2% after secondary procedures. Of the 26 patient and 18 procedural characteristics analyzed, the following variables best predicted risk of a 1-year all-cause mortality: age, NYHA class, renal dysfunction, anticoagulant use, ischemic cardiomyopathy, diabetes, BMI, procedure time, myocardial infarction, valve surgery, and hypertrophic cardiomyopathy (Table).

Conclusion

In WRAP-IT patients undergoing secondary procedures, the only procedure characteristics that had any association with all-cause 1-year mortality risk was procedure time suggesting that most of the risk factors of mortality are non-modifiable. Baseline patient characteristics and co-morbidities were the principal risk factors of all-cause 1-year mortality. Specifically, increasing age, NYHA class, and a history of renal dysfunction were strongly associated with mortality.

Is there clinical utility to replacement of an implantable loop recorder in patients who have previously undergone cryoballoon pulmonary vein isolation?

Funding Acknowledgements

Type of funding sources: None.

Background

Implantable loop recorders (ILRs) are used for long-term ECG monitoring following catheter ablation in patients (pts) with atrial fibrillation (AF) to guide clinical management. However, little is known about what do when the ILR reaches end of service (EOS).

Purpose

To identify pts who underwent replacement of their ILR and determine the diagnostic yield and clinical utility of the replacement device.

Methods

We enrolled 222 consecutive pts with AF who underwent cryoballoon pulmonary vein isolation (CB PVI) and had an ILR. We identified pts who subsequently underwent ILR replacement. The diagnostic and clinical utility of the newly replaced ILR was determined.

Results

The cohort included 56 pts (64 + 9 years; 35 [63%] male; 27 [48%] PAF; CHA2DS2-VASc 2.3 ± 1.5) in whom the initial ILR reached EOS. They were followed for 3.7 ± 2.1 years. Recurrent AF was observed in 41 (73%) of these pts; this triggered an intervention in 17 (41%) pts (Figure). Of the other 15 (27%) pts without any documented AF, anticoagulation was withheld in 13 [87%] pts. Following ILR replacement, 33 (80%) of the 41 pts had more AF (n=11 [33%] required an intervention) and 5 additional pts had AF for the first time.

Conclusions

Our data show that after CB PVI, ILRs help guide decisions regarding rhythm management and oral anticoagulation. When the initial ILR was replaced by a second ILR, AF was detected (often for the first time) in some patients; the findings were used to guide clinical decision making in the entire cohort. Thus, at this time, it remains undefined when ECG monitoring of these pts can be stopped because it is no longer clinical meaningful.

[89Zr]ZrDFO-CR011 positron emission tomography correlates with response to glycoprotein non-metastatic melanoma B-targeted therapy in triple negative breast cancer

There is a need for prognostic markers to select patients most likely to benefit from antibody drug conjugate (ADC) therapy. We quantified the relationship between pre-treatment positron emission tomography (PET) imaging of glycoprotein non-metastatic melanoma B (gpNMB) with 89Zr-labeled anti-gpNMB antibody ([89Zr]ZrDFO-CR011) and response to ADC therapy (CDX-011) in triple negative breast cancer (TNBC). First, we compared different PET imaging metrics and found that standardized uptake values (SUV) and tumor-to-heart SUV ratios (SUVR) were sufficient to delineate differences in radiotracer uptake in the tumor of four different cell- and patient-derived tumor models and achieved high standardized effect sizes. These tumor models with varying levels of gpNMB expression were imaged with [89Zr]ZrDFO-CR011 followed by treatment with a single bolus injection of CDX-011. The percent change in tumor volume relative to baseline (% CTV) was then correlated with SUVmean of [89Zr]ZrDFO-CR011 uptake in the tumor. All gpNMB-positive tumor models responded to CDX-011 over 6 weeks of treatment, except one patient-derived tumor re-grew after 4 weeks of treatment. As expected, the gpNMB-negative tumor increased in volume by 130 {plus minus} 59 % at endpoint. The magnitude of pre-treatment SUV had the strongest inverse correlation with the % CTV at 2 - 4 weeks after treatment with CDX-011 (Spearman ρ = -0.8). However, pre-treatment PET imaging with [89Zr]ZrDFO-CR011 did not inform on which tumor types will re-grow over time. Other methods will be needed to predict resistance to treatment.

Molecular alterations associated with improved outcome in patients with glioblastoma treated with Tumor-Treating Fields

Background

The genomic and overall biologic landscape of glioblastoma (GB) has become clearer over the past 2 decades, as predictive and prognostic biomarkers of both de novo and transformed forms of GB have been identified. The oral chemotherapeutic agent temozolomide (TMZ) has been integral to standard-of-care treatment for nearly 2 decades. More recently, the use of non-pharmacologic interventions, such as application of alternating electric fields, called Tumor-Treating Fields (TTFields), has emerged as a complementary treatment option that increases overall survival (OS) in patients with newly diagnosed GB. The genomic factors associated with improved or lack of response to TTFields are unknown.

Methods

We performed comprehensive genomic analysis of GB tumors resected from 55 patients who went on to receive treatment using TTFields, and compared results to 57 patients who received standard treatment without TTFields.

Results

We found that molecular driver alterations in NF1, and wild-type PIK3CA and epidermal growth factor receptor (EGFR), were associated with increased benefit from TTFields as measured by progression-free survival (PFS) and OS. There were no differences when stratified by TP53 status. When NF1, PIK3CA, and EGFR status were combined as a Molecular Survival Score, the combination of the 3 factors significantly correlated with improved OS and PFS in TTFields-treated patients compared to patients not treated with TTFields.

Conclusions

These results shed light on potential driver and passenger mutations in GB that can be validated as predictive biomarkers of response to TTFields treatment, and provide an objective and testable genomic-based approach to assessing response.

TAMI-15. PROSTATE SPECIFIC MEMBRANE ANTIGEN EXPRESSION IN GLIOBLASTOMA TUMOR AND ENDOTHELIAL CELLS

INTRODUCTION

Prostate specific membrane antigen (PSMA) has emerged in recent years as a potential target for PET imaging of CNS tumors. Originally studied for imaging in prostate cancer, it was incidentally found to have selective uptake in some CNS tumors. Early studies have shown promise for PSMA tracer use in glioblastoma (GBM), but more research is needed to characterize the PSMA expression profile in GBM.

METHODS

Formalin-fixed paraffin-embedded tissues of 26 GBMs were immunostained with PSMA antibody. Stained sections were scored, using 5 images per tumor, in total 130 observations. Sections were assessed for extent and intensity of PSMA expression, in tumor cells and neovascular endothelial cells. Extent of expression: 0% (none), 1-9% (very low), 10-39% (low), 40-69% (moderate), &gt; 70% (high). Intensity of expression: no staining (none); barely perceptible staining (low); readily apparent at low magnification (moderate); and maximum-intensity staining (high).

RESULTS

Extent of PSMA expression in tumor cells was mostly very low (76 out of 130, 58%), but intensity was often moderate (42, 32%), low (41, 32%), or high (39, 30%). The most prevalent combination was very low extent with low or moderate intensity (both 30, 23%). Endothelial cells were absent in 61 (47%) sections. Extent of expression in endothelial cells was mostly high (28, 41%), and intensity was often moderate (25, 36%) or high (20, 29%). The most prevalent combination was high extent with moderate (14, 20%) or high intensity (13, 19%).

CONCLUSION

PSMA expression was variable and was seen in both vascular endothelial cells and tumor cells. The mechanism of PSMA expression in GBM may not be straightforward, but rather may vary by cell type and tumor mutation status. Further tissue studies to understand the specific mechanism are needed to establish the potential use of PSMA PET as a neuroimaging modality in GBM.

CSIG-09. ASSESSMENT OF TUMOR TREATING FIELDS (TTFields) COMBINED WITH TRICHOSTATIN A (TSA) IN PATIENT-DERIVED GLIOBLASTOMA (GBM) CELLS

BACKGROUND

TTFields therapy is a non-invasive biophysical approach for GBM patient treatment. TTFields produce an anti-mitotic effect by destabilizing microtubule polymerization and interrupting cell division. However, epigenetic modifications that may be induced by TTFields remain unknown. To address this, TTFields were applied to patient-derived GBM cells ± the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) and cellular proliferation was assessed. HDAC activity was also measured after TTFields application.

METHODS

GBM cells were isolated from a newly-diagnosed patient tumor (IDH-WT, unmethylated MGMT promoter). Cells were grown in DMEM/F12 media with 10% FBS and gentamicin. Cells were plated on plastic coverslips (1×104cells/coverslip) and incubated overnight. TTFields were applied at 200 kHz (field intensity of ~1.6 V/cm) for 6 days. For the last 2 days of TTFields, cells were incubated with DMSO or 250 nM TSA. Cells were harvested and counted to assess proliferation (n=4-5/group). To determine if TTFields have a direct effect on HDAC activity, TTFields were applied as described and nuclei were extracted. Nuclear HDAC activity was measured using a commercial kit (n=2-3/group). Cell counts were compared with one-way ANOVA and Tukey multiple comparisons with p&lt; 0.05 considered significant.

RESULTS

Cell counts for the DMSO control group, TSA only, TTFields only, and the combination were: 643,400 ± 111,384, 233,800 ± 144,200, 90,775 ± 45,209, and 41,520 ± 36,168, respectively (mean ± SD; ANOVA p&lt; 0.0001). There was no statistical difference between the TTFields only and TSA only or TTFields + TSA groups, with all other comparisons statistically significant. For the HDAC activity measurements, control nuclei were 1068 ± 135 pmol/min/mg and TTFields-treated nuclei were 1301 ± 313.6 pmol/min/mg and were not statistically different.

CONCLUSIONS

The addition of TSA to TTFields did not alter cellular proliferation more than TTFields alone and TTFields did not alter HDAC activity in these GBM cells.

CBIO-02. IN VITRO TUMOR TREATING FIELDS (TTFields) REDUCE PROLIFERATION AND ALTER MLH1 EXPRESSION IN TEMOZOLOMIDE RESISTANT (TMZR) PATIENT-DERIVED GLIOBLASTOMA (GBM) CELLS

BACKGROUND

TTFields therapy is approved as a monotherapy for the treatment of recurrent GBM, tumors that often have acquired resistance to TMZ. To examine TTFields efficacy in the context of TMZR in vitro, TTFields were applied to TMZR GBM cells to assess proliferation, clonogenicity, and changes in expression of O6-methylguanine-DNA methyltransferase (MGMT) that confers TMZ resistance and DNA Mismatch Repair Protein Mlh1 (MLH1) that may confer TMZ sensitivity.

METHODS

15-037 GBM cells were isolated from a newly-diagnosed patient tumor (IDH-WT, unmethylated MGMT promoter. Cells were grown in DMEM/F12 media with 10% FBS and gentamicin. U-251 MG cells and 15-037 cells were incubated with 100 µM TMZ for three 5-day cycles to establish TMZR. TMZR cells were plated on coverslips (1×104cells/coverslip) and incubated overnight prior to TTFields application. TTFields were applied at 200 kHz (field intensity of ~1.6 V/cm) for 14 days. Then coverslips (n=3/group) were harvested, counted, and replated for clonogenic assay at 1000 cells/35mm2 well. Clonogenic assay plates were stained with crystal violet, imaged, and colonies counted. Additional coverslips (n=3/group) were harvested and MGMT and MLH1 expression were assessed by qRT-PCR with the delta-delta Ct method using GAPDH as housekeeping control. Cell counts and colony counts were compared with two-tailed t-test with significance at p&lt; 0.05.

RESULTS

In U-251 MG and 15-037 TMZR cells, TTFields application significantly reduced both cell counts and clonogenic assay colony counts compared to untreated controls (U-251 MG: 45.4% and 26.5%; 15-037: 96.2% and 60.9%, respectively, p&lt; 0.05). In both TMZR cell lines, MGMT expression was unchanged by TTFields, but MLH1 expression increased 2.2 fold in U-251 MG cells and 7.1 fold in 15-037 cells after TTFields application.

CONCLUSIONS

Not only are TMZR GBM cells sensitive to TTFields in vitro, but TTFields increased expression of MLH1 which may be able to reduce resistance to TMZ.

Defining the optimal blanking period duration after cryoballoon pulmonary vein isolation in patients with atrial fibrillation who have never been treated with an antiarrhythmic drug

Background

Cryoballoon (CB) pulmonary vein isolation (PVI) is an approved method for ablation in patients with paroxysmal (PAF) or persistent (PeAF) atrial fibrillation (AF). Although the first 90 days post-ablation are considered within the blanking period (BP), the optimal duration of the BP remains undefined.

Purpose

To objectively define the BP duration in pts undergoing CB PVI by evaluating a cohort never treated with an antiarrhythmic drug (AAD).

Methods

We enrolled consecutive pts with either PAF or PeAF who underwent initial CB PVI; all pts had an implantable loop recorder (ILR) for long-term ECG monitoring. No pt received an AAD either before or after ablation. We determined the time to last AF episode within the first 90 days of ablation. We then correlated this to the likelihood a patient had recurrent AF between 91 and 365 days of ablation.

Results

There were 45 pts (67±8 years; 26 [58%] male; 40 [89%] PAF; CHA2DS2-VASc 2.6±1.3). We defined 4 distinct groups post ablation based on whether or not they had AF in the BP: (1) no AF days 0–90 (n=19 [42%]), (2) last AF days 0–30 (n=11 [24%]), (3) last AF days 31–60 (n=3 [7%]), and (4) last AF days 61–90 (n=12 [27%]). After the 90-day BP, 15 (33%) pts had AF recurrence. Pts with no AF and those with AF only within 30 days of ablation had similar long-term outcome; however, recurrent AF more than 32 days after ablation predicted long-term ablation failure (Figure).

Conclusion

The post CB PVI blanking period is just a month. AF recurrences beyond a month in patients not on an AAD are associated with AF recurrence in the majority of pts.

Funding Acknowledgement

Type of funding sources: None. Blanking Group by AF Recurrence

Role of novel cancer gene SLITRK3 to activate NTRK3 in squamous cell lung cancer

The development of targeted therapies that inhibit cancer-driving oncogenes has improved outcomes of patients diagnosed with lung adenocarcinoma (LUAD). In contrast, patients diagnosed with lung squamous cell carcinoma (LUSC) suffer worse survival outcomes and lack effective targeted treatment options. Identification of molecular drivers of LUSC to support development of targeted treatments is urgently needed. Addressing this need, the current report introduces the novel cancer gene SLIT- and NTRK-like family member 3 (SLITRK3) and its role in activating the neurotrophic receptor tyrosine kinase 3 (NTRK3) in LUSC cells. Multiple genome-wide data sets from patient samples were produced by us or downloaded from public databases to analyze tumor gene copy number aberrations, mRNA expression and associated survival outcomes. An accompanying mechanistic study employed LUSC cell lines and multiple methods, including in situ immunofluorescence, sphere-formation assay, and fluorescence-activated cell sorting analysis of the CD133-positive cell fraction. Altogether, the results indicate that gene amplification and consequent high expression of SLITRK3 in LUSC is associated with worse outcomes and induces SLITRK3-dependent activation of NTRK3 to promote a cancer stem cell phenotype that is inhibited by existing NTRK-targeted inhibitors. Based on a recent literature search, this is the first report of a mechanistic role for SLITRK3 in cancer.

Mobile digital x-ray and portable cartridge based nucleic acid amplification test machines for point-of-care diagnosis of TB in rural India

BACKGROUND

There is no experience of point-of-care (POC) microbiological confirmation for TB in India in field settings.

METHODS

Under the TB-Free Haryana project, a mobile van-mounted digital x-ray and portable GeneXpert system screened all presumptive TB patients with strong clinic-radiological suspicion for TB.

RESULTS

Of 1673 x-rays, 215 (13%) had findings suggestive of TB, 109 had strong clinical suspicion and were eligible for POC GeneXpert, in whom a test was performed in 82 (75%) cases; 59 (72%) tested positive and were initiated on treatment within 24 h.

CONCLUSIONS

A mobile van equipped with digital x-ray and POC GeneXpert is feasible and has a good success rate with potential for replication.

Abstract 1007: Patient-derived metastatic renal carcinoma cells are highly sensitive to in vitro Tumor Treating Fields (TTFields)

Background: Until the advent of checkpoint inhibitor (CI) therapies, renal cell carcinoma (RCC) was clinically challenging to treat given its radio- and chemotherapy resistance. Despite the advances with CIs, patients with brain metastases derived from RCC still face challenges with treatment due to limited brain penetration of CI compounds. Anti-mitotic TTFields therapy is FDA-approved for the treatment of glioblastoma and mesothelioma, and clinical trials are underway for the application of TTFields therapy to primary lung cancer as well as lung cancer brain metastases. In this study, in vitro TTFields were applied to patient-derived brain metastasis RCC cells to determine the potential efficacy of this emerging treatment modality.

Methods: This study was approved by the Institutional Review Board. A single-cell suspension was generated from tumor tissues obtained from a patient with newly-diagnosed RCC brain metastasis (male, age 52, mutant p53). Cells were cultured in DMEM/F12 media with 10% fetal bovine serum and gentamicin. Prior to TTFields initiation, cells were plated on plastic coverslips (1×104cells/coverslip; n=8/group) and incubated overnight. Then, TTFields were applied at 200 kHz with a field intensity of ~1.6 V/cm for 14 days, with one group of coverslips maintained as untreated controls. At the conclusion of the experiment, cells were harvested, stained with acridine orange/propidium iodide and counted with a Cellometer K2 (Nexcelom Bioscience, Lawrence, MA) that provides viable cell counts and average cell diameter. Groups were compared with a two-tailed t-test (GraphPad Prism v9, GraphPad Software, San Diego, CA) with significance set at P&lt;0.05.

Results: Viable cell count per coverslip for the control group was 149,863 ± 85644 (mean ± SD; n=8) and for the TTFields (200 kHz) group was 1,426 ± 1345 (n=6, 2 coverslips had no cell recovery). Average cell diameter was 9.713 ± 0.6312 for the control group and 16.92 ± 2.903 for the TTFields group. TTFields application significantly reduced cell count (P=0.0012) and increased the average cell diameter (P&lt;0.0001) compared to the controls.

Conclusions: TTFields application (200 kHz) demonstrated efficacy by markedly reducing cell proliferation (i.e., decreased cell counts) in RCC. The increase in average cell diameter observed with TTFields is consistent with previously reported findings of other research groups also showing increases in cell volume with TTFields in multiple cancer types (brain, lung, pancreas, breast, ovarian, and cervical). This study is the first to demonstrate the efficacy of in vitro TTFields treatment in patient-derived RCC and suggests that patients with renal carcinoma brain metastases may benefit from TTFields therapy.

Citation Format: Sharon K. Michelhaugh, Blake C. Walker, Susan Coombe, Sandeep Mittal. Patient-derived metastatic renal carcinoma cells are highly sensitive to in vitro Tumor Treating Fields (TTFields) [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 1007.

Gliosarcoma vs. glioblastoma: a retrospective case series using molecular profiling

Background

Gliosarcoma (GS) refers to the presence of mesenchymal differentiation (as seen using light microscopy) in the setting of glioblastoma (GB, an astrocytoma, WHO Grade 4). Although the same approach to treatment is typically adopted for GS and GB, there remains some debate as to whether GS should be considered a discrete pathological entity. Differences between these tumors have not been clearly established at the molecular level.

Methods

Patients with GS (n=48) or GB (n=1229) underwent molecular profiling (MP) with a pan-cancer panel of tests as part of their clinical care. The methods employed included next-generation sequencing (NGS) of DNA and RNA, copy number variation (CNV) of DNA and immunohistochemistry (IHC). The MP comprised 1153 tests in total, although results for each test were not available for every tumor profiled. We analyzed this data retrospectively in order to determine if our results were in keeping with what is known about the pathogenesis of GS by contrast with GB. We also sought novel associations between the MP and GS vs. GB which might improve our understanding of pathogenesis of GS.

Results

Potentially meaningful associations (p<0.1, Fisher’s exact test (FET)) were found for 14 of these tests in GS vs. GB. A novel finding was higher levels of proteins mediating immuno-evasion (PD-1, PD-L1) in GS. All of the differences we observed have been associated with epithelial-to-mesenchymal transition (EMT) in other tumor types. Many of the changes we saw in GS are novel in the setting of glial tumors, including copy number amplification in LYL1 and mutations in PTPN11.

Conclusions

GS shows certain characteristics of EMT, by contrast with GB. Treatments targeting immuno-evasion may be of greater therapeutic value in GS relative to GB.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12883-021-02233-5).

Randomized Controlled Trial on the Promotion of Sexual Health Using "Self-Care Interventional Package" in Men Who have Sex with Men

Purpose:

Men who have sex with men (MSM) is a vulnerable group, who have been neglected and discriminated. Such discrimination decreases their access to health care and increases the spread of sexually transmitted infections (STIs) and human immunodeficiency virus (HIV).

Aims and Objective:

The objective is to evaluate the effectiveness of “self-care interventional package” on the promotion of sexual health, among MSM.

Materials and Methods:

A randomized controlled trial was conducted on MSM from two nongovernmental organization centers of Chandigarh, which were randomized by simple random sampling into a control and experimental group. Over a period of 1 month, a total of 115 MSM were found eligible; 55 in control group and 60 in experimental group. Data were collected by a personal interview, after taking consent, in a comfortable and private environment. The Self-Care Interventional Package on the promotion of sexual health was developed in the form of flash book and booklet, and delivered by one-to-one interaction. Three follow-ups were done weekly for motivation in both the groups. Postintervention assessment was conducted after 1 month.

Results:

There was a statistically significant (P < 0.01) improvement in knowledge about prevention and management of STIs and HIV, getting vaccinated for Hepatitis B and regular self check-up. Statistically significant reduction in unsafe sexual practices was noted among the MSM of experimental group.

Conclusion:

The self-care interventional package for the promotion of sexual health was effective in improving the sexual heath of the MSM population.

Is the optimal blanking period duration after cryoballoon pulmonary vein isolation impacted by use of antiarrhythmic drugs?

Funding Acknowledgements

Type of funding sources: None.

Background

Cryoballoon pulmonary vein isolation (CB) is an accepted method for ablation in patients with atrial fibrillation (AF). A three-month blanking period (BP) is commonly used in clinical trials and practice. However, when the optimal BP duration differs in patients (pts) on or off an antiarrhythmic drug (AAD) at time of ablation remains undefined.

Objective

To compare the BP duration in pts undergoing CB while either taking or not taking an AAD.

Methods

We enrolled consecutive pts with AF who had CB PVI while on an AAD. All pts had an implantable loop recorder (ILR). We prospectively followed all pts and determined the time to last AF episode during the 90-day post-PVI BP. This was then correlated with likelihood of having an AF recurrence between 3-12 months post-PVI.

Results

The cohort included 164 pts (66 ± 9 years; 97 [60%] male; 90 [55%] PAF; CHA2DS2-VASc 2.7 ± 1.7). Ablation was performed with 92 (56%) pts taking an AAD, which was stopped at a median of 80 [36, 105] days post-PVI. We defined 4 distinct groups: (1) no AF in 90-day BP (n = 75 [46%]); (2) last AF within 30 days of PVI (n = 32 [20%]); (3) last AF within 60 days of PVI (n = 17 [10%]); and (4) last AF within 90 days of PVI (n = 40 [24%]). Following the 90-day BP, 81 (49%) pts had a recurrence of AF. Long-term freedom from recurrent AF was similar in pts who did and did not use an AAD, irrespective of BP duration (Figure).

Conclusion

Our data suggest that the optimal BP duration in AF patients undergoing CB PVI while taking an AAD is 30 days. An AF recurrence after 30 days is associated with a very high likelihood of recurrent AF during longer-term follow-up, irrespective of whether an AAD is being used or not. Abstract Figure.

Defining the blanking period duration after cryoballoon pulmonary vein isolation in patients taking an antiarrhythmic drug

Funding Acknowledgements

Type of funding sources: None.

Background

Cryoballoon pulmonary vein isolation (CB) is an accepted method for ablation in patients with atrial fibrillation (AF). A three-month blanking period (BP) is commonly used in clinical trials and practice. However, the actual BP duration in patients (pts) on an antiarrhythmic drug (AAD) at time of ablation remains undefined.

Objective

To objectively define the BP duration in pts undergoing CB while taking an AAD.

Methods

We enrolled consecutive pts with AF who had CB PVI while on an AAD. All pts had an implantable loop recorder (ILR). We prospectively followed all pts and determined the time to last AF episode during the 90-day post-PVI BP. This was then correlated with likelihood of having an AF recurrence between 3-12 months post-PVI.

Results

The cohort included 92 pts (66 ± 10 years; 62 [67%] male; 33 [36%] PAF; CHA2DS2-VASc 2.6 ± 1.7). AADs used included dofetilide (42), dronedarone (14), amiodarone (25), sotalol and propafenone (3 each), and flecainide (5). The AAD was stopped at a median of 80 [36, 105] days post-PVI.  We defined 4 distinct groups: (1) no AF in 90-day BP (n = 45 [49%]); (2) last AF within 30 days of PVI (n = 17 [18%]); (3) last AF within 60 days of PVI (n = 13 [15%]); and (4) last AF within 90 days of PVI (n = 17 [18%]). Following the 90-day BP, 47 (51%) pts had a recurrence of AF. Once recurrent AF was observed &gt; 30 days post-ablation, patients had high likelihood of having a long term AF recurrence (p = 0.037, Figure).

Conclusion

Our data suggest that the optimal BP duration in AF patients undergoing CB PVI while taking an AAD is 30 days. An AF recurrence after 30 days is associated with a very high likelihood of recurrent AF during longer-term follow-up. Abstract Figure.

Depression and tryptophan metabolism in patients with primary brain tumors: Clinical and molecular imaging correlates

Patients with brain tumors have an increased risk for depression, whose underlying pathomechanism may involve dysregulated tryptophan/kynurenine metabolism. In this study, we analyzed the relation of depressive symptoms to clinical and tumor characteristics as well as cerebral and systemic tryptophan metabolism in patients with primary brain tumors. Sixty patients with newly-diagnosed or recurrent primary brain tumor underwent testing with the Beck Depression Inventory-II (BDI-II), and 34 patients also had positron emission tomography (PET) imaging with alpha-[¹¹C]methyl-L-tryptophan (AMT). BDI-II scores were correlated with clinical and tumor-related variables, cerebral regional AMT metabolism measured in the non-tumoral hemisphere, and plasma tryptophan metabolite levels. Sixteen patients (27%) had BDI-II scores indicating depression, including 6 with moderate/severe depression. High BDI-II scores were independent of clinical and tumor-related variables except lower Karnofsky Performance Status scores. In patients with recurrent malignant gliomas, depression was associated with shorter survival (hazard ratio: 3.7; p = 0.048). High BDI-II total and somatic subscale scores were associated with higher frontal cortical and thalamic AMT metabolic values measured on PET. In contrast, plasma tryptophan and kynurenine metabolite levels did not correlate with the BDI-II scores. In conclusion, our results confirm previous data that depression affects more than ¼ of patients with primary brain tumors, it is largely independent of tumor characteristics and is associated with shorter survival in patients with recurrent malignant gliomas. On PET imaging, higher tryptophan metabolism in the frontal cortex and thalamus was found in those with brain tumor-associated depression and supports the role of dysregulated tryptophan/kynurenine metabolism in this condition.

A study on the effects of stress and hopelessness in isolated COVID-19 patients in relation to severity of infection

Introduction

In India, Coronavirus pandemic started in the month of march 2020 and is growing day by day. In view of India being one of the most populous countries, it is hard to follow social distancing and abide by the lockdown rules. Therefore, as of December 2020, total number of covid-19 cases has crossed the 10 million. But the recovery rate in India is high, so the fear due to Covid-19 has decreased in intensity.

Objectives

To assess level of perceived stress in isolated covid-19 patients To assess level of hopelessness in isolated covid-19 patients

Methods

30 Patients of diagnosed Covid-19 positive,who were isolated in covid care setting in Uttar Pradesh(India),above 18yrs of age,of both sexes and willing to participate in the study were included, their socio-demographic data collected. Beck’s hopelessness scale and Perceived stress scale were administered. Infection severity upto moderate was selected and ICU patients were excluded. Results were analysed using SPSS software.

Results

It was observed that level of hopelessness increased with increasing age and increasing severity of covid-19.Level of perceived stress also increased with increasing age and increasing covid severity. There was no relation seen between hopelessness level and perceived stress level and no difference was seen in the levels of hopelessness and perceived stress between the two sexes.

Conclusions

Levels of hopelessness and stress increased with increasing age and increasing severity of covid-19.No relation seen between hopelessness level and perceived stress level and no difference was seen in the levels of hopelessness and perceived stress between the two sexes.

Disclosure

No significant relationships.

Mechanisms of temozolomide resistance in glioblastoma - a comprehensive review

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and has an exceedingly low median overall survival of only 15 months. Current standard-of-care for GBM consists of gross total surgical resection followed by radiation with concurrent and adjuvant chemotherapy. Temozolomide (TMZ) is the first-choice chemotherapeutic agent in GBM; however, the development of resistance to TMZ often becomes the limiting factor in effective treatment. While O6-methylguanine-DNA methyltransferase repair activity and uniquely resistant populations of glioma stem cells are the most well-known contributors to TMZ resistance, many other molecular mechanisms have come to light in recent years. Key emerging mechanisms include the involvement of other DNA repair systems, aberrant signaling pathways, autophagy, epigenetic modifications, microRNAs, and extracellular vesicle production. This review aims to provide a comprehensive overview of the clinically relevant molecular mechanisms and their extensive interconnections to better inform efforts to combat TMZ resistance.

COVID-19 lockdown: a rare opportunity to establish baseline pollution level of air pollutants in a megacity, India

This paper analyses air quality data from megacity Delhi, India, during different periods related to the COVID-19, including pre-lockdown, lockdown and unlocked (post-lockdown) (2018-2020) to determine what baseline levels of air pollutants might be and the level of impact that could be anticipated under the COVID-19 lockdown emission scenario. The results show that air quality improved significantly during the lockdown phases, with the most significant changes occurring in the transportation and industrially dominated areas. A pronounced decline in PM_{2.5 and} PM₁₀ up to 63% and 58%, respectively, was observed during the lockdown compared to the pre-lockdown period in 2020. When compared to 2018 and 2019, they were lower by up to 51% and 61%, respectively, dropping by 56% during unlock. Some pollutants (NOx and CO) dropped significantly during lockdown, while SO₂ and O₃ declined only slightly. Moreover, when compared between the different phases of lockdown, the maximum decline for most of the pollutants and air quality index occurred during the lockdown phase 1; thus, this period was used to report the COVID-19 baseline threshold values (CBT; threshold value is the upper limit of baseline variation). Of the various statistical methods used median + 2 median absolute deviation (mMAD) was most suitable, indicating CBT values of 143 and 75 ug/m³ for PM₁₀ and PM_2.5, respectively. This results although preliminary, but it gives a positive indication that temporary lockdown can be considered as a boon to mitigate the damage we have done to the environment. Also, this baseline levels can be helpful as a first line of information to set future target limits or to develop effiective management policies for achieving better air quality in urban centres like Delhi.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13762-021-03142-3.

The oncolytic Newcastle disease virus as an effective immunotherapeutic strategy against glioblastoma

Glioblastoma is the most frequent primary brain tumor in adults, with a dismal prognosis despite aggressive resection, chemotherapeutics, and radiotherapy. Although understanding of the molecular pathogenesis of glioblastoma has progressed in recent years, therapeutic options have failed to significantly change overall survival or progression-free survival. Thus, researchers have begun to explore immunomodulation as a potential strategy to improve clinical outcomes. The application of oncolytic virotherapy as a novel biological to target pathogenic signaling in glioblastoma has brought new hope to the field of neuro-oncology. This class of immunotherapeutics combines selective cancer cell lysis prompted by virus induction while promoting a strong inflammatory antitumor response, thereby acting as an effective in situ tumor vaccine. Several investigators have reported the efficacy of experimental oncolytic viruses as demonstrated by improved long-term survival in cancer patients with advanced disease. Newcastle disease virus (NDV) is one of the most well-researched oncolytic viruses known to affect a multitude of human cancers, including glioblastoma. Preclinical in vitro and in vivo studies as well as human clinical trials have demonstrated that NDV exhibits oncolytic activity against glioblastoma, providing a promising avenue of potential treatment. Herein, the authors provide a detailed discussion on NDV as a mode of therapy for glioblastoma. They discuss the potential therapeutic pathways associated with NDV as demonstrated by in vitro and in vivo experiments as well as results from human trials. Moreover, they discuss current challenges, potential solutions, and future perspectives in utilizing NDV in the treatment of glioblastoma.

Atypical representation of sensorimotor cortex in a patient with autism and epilepsy confirmed by direct electrocortical stimulation

Prior studies have used functional neuroimaging to demonstrate that the organization of the autistic brain is different from that of the non-autistic brain. Similarly, patients with epilepsy have also shown cortical reorganization. We present a case study that provides direct confirmation of disorganized sensorimotor distribution in a patient with autism spectrum disorder and epilepsy. To our knowledge, this is the first time cortical mapping directly showing abnormal cortical organization in a patient with autism spectrum disorder and epilepsy has been reported in the literature.

Case Report: Metastatic Bronchopulmonary Carcinoid Tumor to the Pineal Region

Intracranial spread of a systemic malignancy is common in advanced staged cancers; however, metastasis specifically to the pineal gland is a relatively rare occurrence. A number of primary lesions have been reported to metastasize to the pineal gland, the most common of which is lung. However, metastasis of a bronchial neuroendocrine tumor to the pineal gland is a seldom-reported entity. Here, we present a 53-year-old female who presented with worsening headaches and drowsiness. MRI brain revealed a heterogeneously enhancing partially cystic mass in the pineal region. The patient had an extensive oncologic history consisting of remote stage IIA invasive breast ductal carcinoma as well as a more recently diagnosed atypical bronchopulmonary neuroendocrine tumor with lymph node metastases. She underwent microsurgical volumetric resection of the large pineal mass and a gross total removal of the tumor was achieved. Histopathology confirmed a metastatic tumor of neuroendocrine origin and the immunohistochemical profile was identical to the primary bronchopulmonary carcinoid tumor. Eight weeks after surgery, she underwent stereotactic radiosurgical treatment to the resection cavity. At 1-year follow-up, the patient remains clinically stable without any new focal neurological deficits and without any evidence of residual or recurrent disease on postoperative MRI. Metastatic neuroendocrine tumors should be considered in the differential diagnosis of pineal region tumors and aggressive surgical resection should be considered in selected patients. Gross total tumor resection may afford excellent local disease control. We discuss the relevant literature on neuroendocrine tumors and current treatment strategies for intracranial metastases of neuroendocrine origin.

Practical consensus recommendations on fertility preservation in patients with breast cancer

Young women diagnosed with cancer today have a greater chance of long-term survival than ever before. Successful survivorship for this group of patients includes maintaining a high quality of life after a cancer diagnosis and treatment; however, lifesaving treatments such as chemotherapy, radiation, and surgery can impact survivors by impairing reproductive and endocrine health. Expert oncologists along with reproductive medicine specialists discuss fertility preservation options in this chapter since fertility preservation is becoming a priority for young women with breast cancer. This expert group used data from published literature, practical experience and opinion of a large group of academic oncologists to arrive at these practical consensus recommendations for the benefit of community oncologists.

Molecular Imaging of Brain Tumor-Associated Epilepsy

Epilepsy is a common clinical manifestation and a source of significant morbidity in patients with brain tumors. Neuroimaging has a pivotal role in neuro-oncology practice, including tumor detection, differentiation, grading, treatment guidance, and posttreatment monitoring. In this review, we highlight studies demonstrating that imaging can also provide information about brain tumor-associated epileptogenicity and assist delineation of the peritumoral epileptic cortex to optimize postsurgical seizure outcome. Most studies focused on gliomas and glioneuronal tumors where positron emission tomography (PET) and advanced magnetic resonance imaging (MRI) techniques can detect metabolic and biochemical changes associated with altered amino acid transport and metabolism, neuroinflammation, and neurotransmitter abnormalities in and around epileptogenic tumors. PET imaging of amino acid uptake and metabolism as well as activated microglia can detect interictal or peri-ictal cortical increased uptake (as compared to non-epileptic cortex) associated with tumor-associated epilepsy. Metabolic tumor volumes may predict seizure outcome based on objective treatment response during glioma chemotherapy. Advanced MRI, especially glutamate imaging, can detect neurotransmitter changes around epileptogenic brain tumors. Recently, developed PET radiotracers targeting specific glutamate receptor types may also identify therapeutic targets for pharmacologic seizure control. Further studies with advanced multimodal imaging approaches may facilitate development of precision treatment strategies to control brain tumor-associated epilepsy.

EXTH-33. VALPROIC ACID ENHANCES THE ANTI-PROLIFERATIVE EFFECT OF TUMOR-TREATING FIELDS ON PATIENT-DERIVED GLIOSARCOMA CELLS IN VITRO

BACKGROUND

Valproic acid (VPA) is an anti-epileptic drug often prescribed for glioma-associated seizures. VPA is also investigated as a potential anti-proliferative cancer treatment due to its histone deacetylase inhibitor activity. Tumor-treating fields (TTFields) are an FDA-approved therapy that reduce proliferation of tumor cells by interfering with microtubule formation during mitosis. In this study, we determined whether the combination of VPA with TTFields in comparison to each treatment alone would alter proliferation or cytotoxicity in patient-derived gliosarcoma cells.

METHODS

Gliosarcoma cells were grown in DMEM/F12 media with 10% fetal bovine serum and gentamicin. Prior to TTFields application and VPA incubation, cells were plated on plastic coverslips (1×104cells/coverslip) and incubated overnight. TTFields were applied to cells at 200 kHz optimal frequency (field intensity of ~1.6 V/cm) for 14 days and/or incubated with VPA at concentrations of 0, 0.25, 0.5, or 1mM. Proliferation was assessed by quantifying total RNA from each coverslip (n=3–4/group). Cytotoxicity was assessed by measuring lactate dehydrogenase (LDH) released into the media (n=8/group). Groups were compared by t-tests.

RESULTS

RNA yields from cells treated with only VPA were unchanged compared to control. TTFields treatment alone reduced RNA yield from 14.85±4.23 to 8.92±1.39 µg (mean± SD; P&lt; 0.05). The addition of 1mM VPA to TTFields further reduced RNA yield to 5.48±1.5 µg (P&lt; 0.03), although VPA alone had no effect. Additionally, 1mM VPA increased media LDH from 4.00±1.3 to 6.68±1.7 AU (mean± SD; P&lt; 0.01), while TTFields alone also increased media LDH to 5.67±0.99 AU (P&lt; 0.02). Media LDH levels due to combined TTFields and 1mM VPA treatment was 5.86±1.2 AU (not statistically different from either alone).

CONCLUSIONS

In patient-derived gliosarcoma cells, TTFields and VPA individually elicited modest cytotoxicity. However, TTFields plus VPA combination treatment reduced proliferation more than TTFields alone, though VPA treatment alone did not induce an anti-proliferative effect.

BIOM-17. BRAF MUTATION IS AN EARLY EVENT IN THE EVOLUTION OF A SUBSET OF GLIOBLASTOMAS AND IS ASSOCIATED WITH INCREASED PD-L1 EXPRESSION

INTRODUCTION

BRAF is a RAF-family kinase that regulates MAPK/ERK signaling. Activating BRAF mutations, including V600E, are common in circumscribed low-grade gliomas of childhood and young adulthood, but are uncommon in infiltrative astrocytomas, including glioblastoma. Their role in glioblastoma initiation and progression requires analysis of large datasets given the low frequency (1.0%) in TCGA IDH-wild-type glioblastomas.

METHODS

Molecular profiling was done on 4679 FFPE gliomas by next-generation sequencing at Caris Life Sciences, of which 3170 underwent RNA-sequencing for gene fusion and 4603 DNA-sequencing for mutations. MGMT promoter methylation was tested by pyrosequencing and PD-L1 IHC was performed using the SP142 clone.

RESULTS

Excluding variants of uncertain significance, BRAF mutations/fusions were most common in pleomorphic xanthoastrocytoma (PXA; N=12/24, 50%), glioneuronal tumors (N=6/13, 46%), pilocytic astrocytoma (PA; N=15/48, 31%), and ganglioglioma (n=5/18, 28%). BRAF fusions were uncommon (N=17), most frequent in PA (N=8/31, 26%) where they were associated with older age at daignosis (P=0.043), and typically involved KIAA1549 as fusion partner (70%). BRAF-mutated/fused glioblastoma patients (N=59/3126, 2%) were younger than BRAF-wild-type glioblastoma patients (54 versus 59 years, P=3.5x10-3); more likely to be MGMT-unmethylated (75% versus 56%, P=5.0x10-3); and 3x more likely to express PD-L1 (55% versus 17%, P=2.1x10-10). In tumors harboring a V600E mutation, the variant allele frequency (VAF) was similar in glioblastoma as in PXA, PA, ganglioglioma, and glioneuronal tumors (median VAF=35%).

CONCLUSIONS

BRAF-mutated glioblastoma were 3x more likely to express PD-L1 than BRAF-wild-type glioblastoma. We observed no differences in BRAF V600E clonality in BRAF-mutated glioblastoma compared to BRAF-mutated PXA, PA, ganglioglioma, and glioneuronal tumors, suggesting BRAF mutation is an initiating event in the clonal evolution of a subset of glioblastoma. There is rationale to evaluate combined BRAF inhibition with checkpoint inhibition in BRAF-mutated glioblastoma, potentially synergizing the complete response profile of the former with the durable response profile of the latter.

STEM-09. INTRINSIC INTERFERON SIGNALING REGULATES THE CELL DEATH OF GLIOBLASTOMA STEM CELLS

Glioblastoma (GBM) is the most common, highly aggressive, and lethal primary brain tumor in adults. Interferon (IFN)-mediated signal transducer and activator of transcription 1 (STAT1) signaling contributes to various aspects of stemness, cell death, cytokine signaling in immune and non-immune cells. However, the role of IFN/STAT1 signaling in stemness, cell death and treatment resistance in GBM is unclear. This study aimed to investigate the cancer cell-intrinsic IFN/STAT1 signaling and its role in cell proliferation, stemness, and apoptosis. By using the metagene scores for type I and type II IFN-responsive genes, we evaluated basal IFN/STAT1 signaling in The Cancer Genome Atlas (TCGA) and in patient-derived cohorts of stem-like cells (GSCs) RNA expression datasets. In-silico analyses were further validated for the constitutive IFN signaling in a subset of GSCs using qPCR, WB and ELISA assays. We employed pharmacological activators and/or inhibitors of IFN/STAT1 signaling in GSCs to study its role in stemness and cell death. We found differential cell-intrinsic type I and type II IFN-signaling markers in GSCs and GBM tumors. High IFN-signaling is associated with mesenchymal phenotype and poor survival outcomes. Acute and chronic GSC exposure to recombinant IFNs reversibly activated both type I and II IFN-signaling in GSCs. IFN-β exposure induced apoptosis in intrinsically high IFN/STAT1-signaling GSCs, but not in the low IFN/STAT1-signaling GSCs. In summary, our findings demonstrate that GBM exhibit differential cell-intrinsic IFN-signaling, and basal IFN/STAT1 is a key factor for IFN-β-mediated cell death in GSCs. However, further mechanistic investigation of intrinsic IFN signaling in GBM, particularly in the stem cell compartment is needed.

Depletion of CLK2 sensitizes glioma stem-like cells to PI3K/mTOR and FGFR inhibitors

The Cdc2-like kinases (CLKs) regulate RNA splicing and have been shown to suppress cell growth. Knockdown of CLK2 was found to block glioma stem-like cell (GSC) growth in vivo through the AKT/FOXO3a/p27 pathway without activating mTOR and MAPK signaling, suggesting that these pathways mediate resistance to CLK2 inhibition. We identified CLK2 binding partners using immunoprecipitation assays and confirmed their interactions in vitro in GSCs. We then tested the cellular viability of several signaling inhibitors in parental and CLK2 knockdown GSCs. Our results demonstrate that CLK2 binds to 14-3-3τ isoform and prevents its ubiquitination in GSCs. Stable CLK2 knockdown increased PP2A activity and activated PI3K signaling. Treatment with a PI3K/mTOR inhibitor in CLK2 knockdown cells led to a modest reduction in cell viability compared to drug treatment alone at a lower dose. However, FGFR inhibitor in CLK2 knockdown cells led to a decrease in cell viability and increased apoptosis. Reduced expression of CLK2 in glioblastoma, in combination with FGFR inhibitors, led to synergistic apoptosis induction and cell cycle arrest compared to blockade or either kinase alone.

Low-temperature electrocautery reduces lead-related complications: insights from the WRAP-IT study

Background

Patients with an existing cardiovascular implantable electronic device (CIED) often require a generator replacement or system upgrade/revision, during which some degree of dissection is usually necessary to free the existing lead(s). Commonly used techniques include blunt dissection, standard surgical electrocautery, or newer forms of electrocautery such as the low-temperature electrosurgical device (PlasmaBlade Soft Tissue Dissection Device) designed to minimize inadvertent thermal injury to leads.

Objective

Determine whether the dissection technique impacts the likelihood of developing a lead-related complication.

Methods

The WRAP-IT trial enrolled patients undergoing CIED replacement, upgrade, revision or de novo CRT-D implant. This analysis excluded patients undergoing a de novo procedure. All adverse events were adjudicated by an independent physician committee. Data were analyzed using Cox proportional hazard regression modeling, controlling for capsulectomies and lead dissections.

Results

5639 patients (mean [±SD] age: 70.6±12.7 years; 28.8% female) underwent a replacement/upgrade/revision. Electrocautery was used in 5203 (92.3%) patients and among these, low-temperature electrocautery was used in 1866 (35.9%) patients. Compared to standard electrocautery, low-temperature electrocautery was used more often when leads were dissected or mobilized (P&lt;0.001) or when a partial or complete capsulectomy was performed (P&lt;0.001). Use of low-temperature electrocautery was associated with a 31% reduction in lead-related complications (HR: 0.69, 95% CI: 0.49–0.98, P=0.037) (Figure).

Conclusion

The low-temperature electrosurgical device (PlasmaBlade) uses precise pulses of radiofrequency energy to dissect tissue with only minimal thermal damage. In this large cohort of replacement, revision, and upgrade procedures, use of low-temperature electrocautery led to significantly fewer lead-related complications.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Medtronic

Hardware challenges with an anticoagulation strategy guided by detection of atrial fibrillation by an implantable loop recorder

Background

A “pill-in-the-pocket” anticoagulation strategy, guided by ECG data from an implantable loop recorder (ILR), has been advocated as a clinical strategy. However, a fundamental requirement is the ability to reliably obtain daily ECG data from patients.

Objective

To determine the reliability of daily ECG data transfer from ILRs.

Methods

We evaluated patients implanted with an ILR in whom we sought to withhold oral anticoagulation (OAC) unless atrial fibrillation (AF) was detected. The ILR transmits data nightly to a bedside monitor. Once received, the data are sent to a central server. Over the course of a month, we tracked for each patient whether ECG data were received by the server.

Results

The study included 170 AF patients with an ILR where we planned to withhold OAC unless AF was documented. Daily ECG data were automatically transmitted and retrievable in only 36 (21%) patients. Two (1%) pts had not a single day of connectivity, 6 (4%) pts were connected &lt;7 days, and 16 (9%) pts were connected &lt;14 days. Wireless connectivity was lost for &gt;48 hours in 89 (52%) patients (Figure). Most patients experienced multiple reasons for data transmission failure within the month.

Conclusions

To determine whether an ILR guided OAC strategy is feasible, reliable daily transmission of ECG data is a fundamental prerequisite. Current technology facilitated daily ECG data transfer in only 1/5 of patients. In the remaining, there was either extended loss of connectivity or no connectivity at all. A “pill-in-the-pocket” anticoagulation approach is currently difficult given existing hardware limitations.

Funding Acknowledgement

Type of funding source: None

Abstract 574: In vitro TTFields enhance the response to temozolomide or radiation in GBM cells from a newly diagnosed patient

Background: Tumor treating fields (TTFields) are FDA-approved for treatment of newly diagnosed and recurrent glioblastoma and are typically initiated after patients have undergone surgical resection, temozolomide, (TMZ) and radiotherapy. In this study, GBM cells generated from a tumor resected from a newly diagnosed glioblastoma patient were treated in vitro with TTFields ± TMZ or treated with in vitro TTFields followed by irradiation to determine if TTFields alter the response to the standard-of-care treatment modalities.

Methods: Single-cell suspensions generated from tumor tissue obtained from a newly diagnosed patient were cultured in DMEM/F12 media with 10% fetal bovine serum and gentamicin. For the TMZ experiment, cells were plated on plastic coverslips (1 × 104cells/coverslip; n=4-6/group) and incubated overnight. TTFields (200 kHz; field intensity of ~1.6 V/cm). were applied with or without 50 µM TMZ for 5 days, followed by the XTT proliferation assay. For the radiation experiment, cells were plated on plastic coverslips (5 × 104cells/coverslip; n=3/group) and incubated overnight. TTFields (200 kHz; field intensity of ~1.6 V/cm). were applied for 3 days followed by irradiation with 0, 2, 4, or 6 Gy. Cells were harvested and plated to assess clonogenic potential. After 3 days, cells were stained with crystal violet and plates were scanned to determine cell counts. Data were analyzed by one-way ANOVA with Tukey's post-hoc test.

Results: In the TTFields/TMZ experiment, control XTT values were 0.665 ± 0.052, TMZ only were 0.480±0.024, TTFields only were 0.550±0.080 and TTFields + TMZ were 0.164 ± 0.062 (mean ± SD; ANOVA p&lt;0.0001). In the TTFields/radiation experiment, there was no statistical difference in cell counts across the radiation doses in the control cells. In the TTFields treated groups, the mean cell counts were 62146, 53324, 41070 and 28680 in the control, 2 Gy, 4Gy, and 6 Gy groups (ANOVA p=0.002).

Conclusions: In GBM cells generated from a newly diagnosed patient's tumor. TTFields application in combination with TMZ reduced cell proliferation by 75%, compared to only 20-30% for either treatment alone. Also, TTFields application prior to radiation significantly reduced cell counts. These results suggest that newly diagnosed patients would benefit from TTFields therapy earlier in the course of treatment.

Citation Format: Sharon K. Michelhaugh, Sandeep Mittal. In vitro TTFields enhance the response to temozolomide or radiation in GBM cells from a newly diagnosed patient [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 574.

Abstract 5254: Combined in vitro TTFields and paclitaxel reduce proliferation and clonogenicity in non-small cell lung cancer (NSCLC) cells from a patient previously treated with standard-of-care

TTFields therapy in conjunction with chemotherapy has been FDA approved as a first line treatment regimen for patients with unresectable malignant pleural mesothelioma. Clinical trials are underway to test the efficacy of TTFields in patients with progressive NSCLC or NSCLC brain metastases following standard-of-care or radiosurgery, respectively. Our study utilized tumor cells extracted from a NSCLC metastatic brain tumor from a patient previously treated with standard-of-care chemoradiation prior to progression to brain metastasis. These patient-derived NSCLC cells were subjected to TTFields application with and without paclitaxel to determine if the combination of TTFields with paclitaxel would be more effective than either treatment alone. Written informed consent was obtained from the patient, who was 60 years-old and female. She received concurrent carboplatin/paclitaxel and radiotherapy to the upper lobe of her left lung prior to discovery and resection of a solitary brain lesion. Cells isolated from the metastatic brain tumor were cultured for 3 passages prior to plating on coverslips (4 × 104 each) in DMEM/F12 media with 10% fetal bovine serum. TTFields were applied at ~1.6 V/cm at 150 kHz. Paclitaxel was added to the media to a final concentration of 5 nM. Cells were treated for 14 days. At the end of the treatment period, some coverslips of cells were lysed and assayed for lactate dehydrogenase (LDH) to represent cell number (n=5) and another set of coverslips of cells were harvested and replated in triplicate for the clonogenic assay (n=3). Groups were compared with one-way ANOVA. Data shown in table are mean ± SD. For the LDH assay, ANOVA p&lt;0.0001. For the clonogenic assay, ANOVA p=0.0003. Overall, the combination of TTFields with paclitaxel produced additive reductions in cell proliferation (75%) and reduced the clonogenic potential (95%) compared to untreated controls. The additive effects of TTFields and paclitaxel suggest that they target different cell populations within a heterogeneous tumor, and that lung cancer patients previously treated with standard-of-care may benefit from TTFields therapy.

Proliferation and clonogenic assay results from combined TTFields and paclitaxelAssayControlPaclitaxel (5 nM)TTFieldsTTFields ± Paclitaxel (5 nM)Proliferation (LDH assay)1.83±0.090.81±0.041.34±0.150.46±0.21Clonogenicity (cell counts)26641±46258697±161717399±59981598±598

Citation Format: Sharon K. Michelhaugh, Sandeep Mittal. Combined in vitro TTFields and paclitaxel reduce proliferation and clonogenicity in non-small cell lung cancer (NSCLC) cells from a patient previously treated with standard-of-care [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5254.

Omeprazole Inhibits Glioblastoma Cell Invasion and Tumor Growth

Background: The aryl hydrocarbon receptor (AhR) is expressed in gliomas and the highest staining is observed in glioblastomas. A recent study showed that the AhR exhibited tumor suppressor-like activity in established and patient-derived glioblastoma cells and genomic analysis showed that this was due, in part, to suppression of CXCL12, CXCR4 and MMP9. Methods: Selective AhR modulators (SAhRMs) including AhR-active pharmaceuticals were screened for their inhibition of invasion using a spheroid invasion assay in patient-derived AhR-expressing 15-037 glioblastoma cells and in AhR-silenced 15-037 cells. Invasion, migration and cell proliferation were determined using spheroid invasion, Boyden chambers and scratch assay, and XTT metabolic assays for cell growth. Changes in gene and gene product expression were determined by real-time PCR and Western blot assays, respectively. In vivo antitumorigenic activity of omeprazole was determined in SCID mice bearing subcutaneous patient-derived 15-037 cells. Results: Results of a screening assay using patient-derived 15-037 cells (wild-type and AhR knockout) identified the AhR-active proton pump inhibitor omeprazole as an inhibitor of glioblastoma cell invasion and migration only AhR-expressing cells but not in cells where the AhR was downregulated. Omeprazole also enhanced AhR-dependent repression of the pro-invasion CXCL12, CXCR4 and MMP9 genes, and interactions and effectiveness of omeprazole plus temozolomide were response-dependent. Omeprazole (100 mg/kg/injection) inhibited and delayed tumors in SCID mice bearing patient-derived 15-037 cells injected subcutaneously. Conclusion: Our results demonstrate that omeprazole enhances AhR-dependent inhibition of glioblastoma invasion and highlights a potential new avenue for development of a novel therapeutic mechanism-based approach for treating glioblastoma.

Multimodal Imaging of Nonenhancing Glioblastoma Regions

BACKGROUND

Clinical glioblastoma treatment mostly focuses on the contrast-enhancing tumor mass. Amino acid positron emission tomography (PET) can detect additional, nonenhancing glioblastoma-infiltrated brain regions that are difficult to distinguish on conventional magnetic resonance imaging (MRI). We combined MRI with perfusion imaging and amino acid PET to evaluate such nonenhancing glioblastoma regions.

METHODS

Structural MRI, relative cerebral blood volume (rCBV) maps from perfusion MRI, and α-[¹¹C]-methyl-l-tryptophan (AMT)-PET images were analyzed in 20 patients with glioblastoma. The AMT uptake and rCBV (expressed as tumor to normal [T/N] ratios) were compared in nonenhancing tumor portions showing increased signal on T2/fluid-attenuated inversion recovery (T2/FLAIR) images.

RESULTS

Thirteen (65%) tumors showed robust heterogeneity in nonenhancing T2/FLAIR hyperintense areas on AMT-PET, whereas the nonenhancing regions in the remaining 7 cases had homogeneous AMT uptake (low in 6, high in 1). AMT and rCBV T/N ratios showed only a moderate correlation in the nonenhancing regions (r = 0.41, P = .017), but regions with very low rCBV (<0.79 T/N ratio) had invariably low AMT uptake.

CONCLUSIONS

The findings demonstrate the metabolic and perfusion heterogeneity of nonenhancing T2/FLAIR hyperintense glioblastoma regions. Amino acid PET imaging of such regions can detect glioma-infiltrated brain for treatment targeting; however, very low rCBV values outside the contrast-enhancing tumor mass make increased AMT uptake in nonenhancing glioblastoma regions unlikely.

1261Geographical variations in the incidence of CIED infection and infection prevention strategies: Update from the global WRAP-IT study

Funding Acknowledgements

Medtronic, Inc.

Introduction

Cardiac Implantable Electronic Device (CIED) infections lead to significant morbidity, mortality, and use of health care resources. There is variation in infection prevention strategies among centers, and it is not clear whether there is also variation in infection rates across different geographies. Recently, WRAP-IT, the largest global randomized trial to evaluate an infection reduction strategy, randomized 6,983 patients to receive an antibacterial envelope (treatment) vs. no envelope (control). The results demonstrated a significant reduction in major CIED infection with the TYRX antibiotic envelope (12-mo infection rate for envelope vs. control 0.7% and 1.2%, respectively; HR, 0.60; 95% [CI], 0.36 to 0.98; P = 0.04).  The purpose of this analysis is to assess geographical variations in patient characteristics, procedural routines, and infection rates.

Methods

The WRAP-IT study enrolled patients undergoing a CIED pocket revision, generator replacement, or system upgrade or an initial implantation of a cardiac resynchronization therapy defibrillator and randomized them to receive the envelope or not, in addition to mandated pre-procedure intravenous antibiotic prophylaxis. To assess geographical variations in infection rates, the control group (per protocol) baseline demographics and procedural characteristics were identified. Major infection was defined as CIED infections resulting in system extraction or revision, long-term antibiotic therapy with infection recurrence, or death.

Results

A total of 3429 control patients were evaluated and followed for a mean of 20.9 ± 8.3 months; 2530 patients from 123 centers in North America, 777 patients from 46 centers in Europe, and 122 patients from 11 centers in Asia/South America. The 24-month Kaplan-Meier major infection rates were 1.2% in North America (30 pts), 2.5% in Europe (16 pts), and 4.3% Asia/South America (5 pts) (see Figure). These geographical variations in the incidence of major CIED infections were significant (overall P = 0.008, univariate). There were differences in baseline patient characteristics, including age, sex, medication use, NYHA Class, and number of previous devices across geographies. Differences also included procedural characteristics, such as device type, use of pocket wash, skin preparation, pre-operative antibiotic drug use, and procedure time.

Conclusion

Major CIED infection rates vary significantly across geographies. The effect of patient demographics and procedural characteristics on these findings will be assessed and presented at EHRA. Insights into geographical variability of CIED infections is important to mitigate infection risk, reduce morbidity and cost.

Abstract Figure. Major CIED Infection Rate by Geography

Molecular features of gliomas with high tumor mutational burden

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Background: TMB-H in gliomas is caused by molecular alterations or alkylator treatment- induced genomic changes characterized by a large number of G:C>A:T transitions. Our study describes the molecular features of TMB-H gliomas. Methods: Gliomas were tested with NextGen sequencing (592 genes), MGMT promoter methylation (MGMT-m) fragment analysis and IHC at Caris Life Sciences. Microsatellite instability (MSI) was test by NGS, FA/IHC. The GC:AT transition rate was calculated as the prevalence of G:A and C:T changes seen in each tumor and > 80% was regarded as high transition(TR-H). TMB values were compared using Wilcoxon Rank Sum. TMB-H was defined as the top quartile of all TMB values (TMB>9). Results: TMB in the 3129 gliomas ranged from 0 to 372 mutations/MB (mean: 8.5, median: 6). TMB-H was observed in 31% of glioblastomas, 16% of astrocytomas (astro) (22% of grade III, 7% of grade I/II) and 22% of oligodendrogliomas (oligo) (32% of grade III and 15% of grade I/II). MGMT-m (58% vs. 47%; p=0.0001), pathogenic (p) or likely p (lp) EGFR (14% vs 10%, p=0.004) and PIK3CA mutations (13% vs. 9%, p=0.002), as well as p/lp in 30 other genes were more prevalent in TMB-H cases (p<0.01). In the 613 TMB-H tumors, TR-H was seen in 12% (73) and was strongly associated with increased TMB (median TMB 52 in TR-H vs. 9 in TR-L,) and MSI-H (7.3% vs. 1.1%), both p<0.0001. Tumors with both TR-H and MSI-H had a mTMB of 114 vs. 49 in TR-H /MSS tumors. MSI-H and TR-L tumors had an mTMB of 23 vs. 9 in MSS /TR-L tumors (p<0.0001). All 5 POLE-MT tumors had TMB of >100 (median 264) and TR-L; 4 of the 5 were also MSI-H. PDL1 IHC had no correlation with TMB, MSI or transition rates. In 89 paired samples taken >150 days apart (regardless of intervening treatment), acquisition of TMB-H was seen in 11 pairs: 8 glioblastomas, 2 grade II/III astro and 2 oligo. In the paired tumors that acquired TMB-H status compared to those that did not, a significantly higher prevalence of MGMT-m (82% vs. 37%, p=0.008) and IDH mutation (64% vs. 19%, p=0.004) were seen. 10 of the 11 recurrent tumors with acquisition of TMB-H had TR-H while none in the other 78 pairs. Conclusions: TMB varies significantly in gliomas and associates with POLE, TR-H and MSI-H, but not with an increase of PD-L1. POLE-mutated tumors had the highest TMB levels. TR-H, an indicator of alkylator-induced phenotype, is associated with a higher TMB than MSI-H, however, TR-H may synergize with MSI-H to further increase TMB. Tumors with an IDH mutation and MGMT-m are more prevalent in tumors with high TMB gain. Further understanding of molecular and immune profile of the TMB-H may facilitate more individualized treatment planning.