The Liquid Biopsy Consortium: Challenges and opportunities for early cancer detection and monitoring.

The emerging field of liquid biopsy stands at the forefront of novel diagnostic strategies for cancer and other diseases. Liquid biopsy allows minimally invasive molecular characterization of cancers for diagnosis, patient stratification to therapy, and longitudinal monitoring. Liquid biopsy strategies include detection and monitoring of circulating tumor cells, cell-free DNA, and extracellular vesicles. In this review, we address the current understanding and the role of existing liquid-biopsy-based modalities in cancer diagnostics and monitoring. We specifically focus on the technical and clinical challenges associated with liquid biopsy and biomarker development being addressed by the Liquid Biopsy Consortium, established through the National Cancer Institute. The Liquid Biopsy Consortium has developed new methods/assays and validated existing methods/technologies to capture and characterize tumor-derived circulating cargo, as well as addressed existing challenges and provided recommendations for advancing biomarker assays.

Extrinsic and intrinsic preanalytical variables affecting liquid biopsy in cancer.

Liquid biopsy, through isolation and analysis of disease-specific analytes, has evolved as a promising tool for safe and minimally invasive diagnosis and monitoring of tumors. It also has tremendous utility as a companion diagnostic allowing detection of biomarkers in a range of cancers (lung, breast, colon, ovarian, brain). However, clinical implementation and validation remains a challenge. Among other stages of development, preanalytical variables are critical in influencing the downstream cellular and molecular analysis of different analytes. Although considerable progress has been made to address these challenges, a comprehensive assessment of the impact on diagnostic parameters and consensus on standardized and optimized protocols is still lacking. Here, we summarize and critically evaluate key variables in the preanalytical stage, including study population selection, choice of biofluid, sample handling and collection, processing, and storage. There is an unmet need to develop and implement comprehensive preanalytical guidelines on the optimal practices and methodologies.

O-Arm Accuracy and Radiation Exposure in Adult Deformity Surgery.

OBJECTIVE: In long thoracolumbar deformity surgery, accurate screw positioning is critical for spinal stability. We assessed pedicle and pelvic screw accuracy and radiation exposure in patients undergoing long thoracolumbar deformity fusion surgery (≥4 levels) involving 3-dimensional fluoroscopy (O-Arm/Stealth) navigation. METHODS: In this retrospective single-center cohort study, all patients aged >18 years who underwent fusion in 2016-2018 were reviewed. O-Arm images were assessed for screw accuracy. Effective radiation doses were calculated. The primary outcome was pedicle screw accuracy (Heary grade). Secondary outcomes were pelvic fixation screw accuracy, radiation exposure, and screw-related perioperative and postoperative complications or revision surgery within 3 years. RESULTS: Of 1477 pedicle screws placed in 91 patients (mean 16.41 ± 5.6 screws/patient), 1208 pedicle screws (81.8%) could be evaluated by 3-dimensional imaging after placement. Heary Grade I placement was achieved in 1150 screws (95.2%), Grade II in 47 (3.9%), Grade III in 10 (0.82%), Grade IV in 1 (0.08%), and Grade V in 0; Grade III-V were replaced intraoperatively. One of 60 (1.6%) sacroiliac screws placed showed medial cortical breach and was replaced. The average O-Arm-related effective dose was 29.54 ± 14.29 mSv and effective dose/spin was 8.25 ± 2.65 mSv. No postoperative neurological worsening, vascular injuries, or revision surgeries for screw misplacement were recorded. CONCLUSIONS: With effective radiation doses similar to those in interventional neuroendovascular procedures, the use of O-Arm in multilevel complex deformity surgery resulted in high screw accuracy, no need for surgical revision because of screw malposition, less additional imaging, and no radiation exposure for the surgical team.

Decoding vesicle-based precision oncology in gliomas.

Extracellular vesicles (EVs) represent a valuable tool in liquid biopsy with tremendous clinical potential in diagnosis, prognosis, and therapeutic monitoring of gliomas. Compared to tissue biopsy, EV-based liquid biopsy is a low-cost, minimally invasive method that can provide information on tumor dynamics before, during, and after treatment. Tumor-derived EVs circulating in biofluids carry a complex cargo of molecular biomarkers, including DNA, RNA, and proteins, which can be indicative of tumor growth and progression. Here, we briefly review current commercial and noncommercial methods for the isolation, quantification, and biochemical characterization of plasma EVs from patients with glioma, touching on whole EV analysis, mutation detection techniques, and genomic and proteomic profiling. We review notable advantages and disadvantages of plasma EV isolation and analytical methods, and we conclude with a discussion on clinical translational opportunities and key challenges associated with the future implementation of EV-based liquid biopsy for glioma treatment.

Calcifying Pseudoneoplasm of the Neuraxis Presenting with Vasogenic Edema and a Perilesional Cyst.

Calcifying pseudoneoplasms of the neuraxis (CAPNONs) are uncommon benign lesions that are rarely diagnosed radiographically. We report an unusual case of a left middle cerebellar peduncle CAPNON with vasogenic edema and a perilesional cyst. The patient was a 36-year-old woman with a 20-year history of left-sided hearing loss that had recently progressed. Computed tomography and magnetic resonance imaging showed a heterogenous calcified lesion with vasogenic edema and a perilesional cyst in the left middle cerebellar peduncle. Although it is a rare radiographic feature of CAPNON, vasogenic edema should be included as a possible feature of this uncommon tumefactive lesion.

Highly Sensitive EGFRvIII Detection in Circulating Extracellular Vesicle RNA of Glioma Patients.

PURPOSE: Liquid biopsy offers an attractive platform for noninvasive tumor diagnosis, prognostication, and prediction of glioblastoma clinical outcomes. Prior studies report that 30% to 50% of GBM lesions characterized by EGFR amplification also harbor the EGFRvIII mutation. EXPERIMENTAL DESIGN: A novel digital droplet PCR (ddPCR) assay for high GC content amplicons was developed and optimized for sensitive detection of EGFRvIII in tumor tissue and circulating extracellular vesicle RNA (EV RNA) isolated from the plasma of patients with glioma. RESULTS: Our optimized qPCR assay detected EGFRvIII mRNA in 81% [95% confidence interval (CI), 68%-94%] of EGFR-amplified glioma tumor tissue, indicating a higher than previously reported prevalence of EGFRvIII in glioma. Using the optimized ddPCR assay in discovery and blinded validation cohorts, we detected EGFRvIII mutation in 73% (95% CI, 64%-82%) of patients with a specificity of 98% (95% CI, 87%-100%), compared with qPCR tumor tissue analysis. In addition, upon longitudinal monitoring in 4 patients, we report detection of EGFRvIII in the plasma of patients with different clinical outcomes, rising with tumor progression, and decreasing in response to treatment. CONCLUSIONS: This study demonstrates the feasibility of detecting EGFRvIII mutation in plasma using a highly sensitive and specific ddPCR assay. We also show a higher than previously reported EGFRvIII prevalence in glioma tumor tissue. Several features of the assay are favorable for clinical implementation for detection and monitoring of EGFRvIII-positive tumors.

Cerebral Arteriovenous Malformation Deep Draining Veins Not Observed on Preoperative Angiography Identified on Postoperative Angiography.

Postoperative digital subtraction angiography (DSA) is the gold standard for establishing a cure of an arteriovenous malformation (AVM) after treatment. The incidence of residual AVM identified on postoperative DSA ranges from 1.8 to 11%. Although this is important for finalizing the treatment of AVMs, postoperative DSA rarely shows new findings that were not previously identified on preoperative imaging. We present a unique case where we identified residual AVM nidus on immediate postoperative DSA that drained into two deep veins that were not evident on preoperative DSA and increased the AVM grade from Spetzler-Martin grade II to III. To our knowledge, this finding has not been previously reported in the literature. We resected the residual AVM nidus identified on postoperative DSA, leading to an angiographic cure. The patient demonstrated a postoperative right-sided supplementary motor area syndrome that resolved over time with therapy. She made a complete functional recovery by her one-month follow-up appointment.

Idiopathic chronic temporal lobe herniation with associated epilepsy.

Herniation of parahippocampal gyrus is usually caused by pressure differentials intracranially, and herniation without known risk factors is extremely rare. We describe a patient with a long history of seizures and a remote status epilepticus event. On magnetic resonance imaging, a presumed left temporal lobe tumor was observed. On neurosurgical consultation, the lesion was identified as a chronic mesial temporal lobe herniation. The patient lacked history that would suggest risk of cerebral herniation. Accurately identifying the patient's chronic temporal lobe herniation radiographically likely saved this patient from unnecessary surgery or biopsy and allowed the patient to receive appropriate conservative care.

Use of a Surgical Stepdown Protocol for Cost Reduction After Transsphenoidal Pituitary Adenoma Resection: A Case Series.

OBJECTIVE: No established standard of care currently exists for the postoperative management of patients with surgically resected pituitary adenomas. Our objective was to quantify the efficacy of a postoperative stepdown unit protocol for reducing patient cost. METHODS: In 2018-2020, consecutive patients undergoing transsphenoidal microsurgical resection of sellar lesions were managed postoperatively in the full intensive care unit (ICU) or an ICU-based surgical stepdown unit based on preset criteria. Demographic variables, surgical outcomes, and patient costs were evaluated. RESULTS: Fifty-four patients (27 stepdown, 27 full ICU; no difference in age or sex) were identified. Stepdown patients were also compared with 634 historical control patients. The total hospital length of stay was no different among stepdown, ICU, and historical patients (4.8 ± 1.0 vs. 5.9 ± 2.8 vs. 4.4 ± 4.3 days, respectively, P = 0.1). Overall costs were 12.5% less for stepdown patients (P = 0.01), a difference mainly driven by reduced facility utilization costs of -8.9% (P = 0.02). The morbidity and complication rates were similar in the stepdown and full ICU groups. Extrapolation of findings to historical patients suggested that ∼$225,000 could have been saved from 2011 to 2016. CONCLUSIONS: These results suggest that use of a postoperative stepdown unit could result in a 12.5% savings for eligible patients undergoing treatment of pituitary tumors by shifting patients to a less acute unit without worsened surgical outcomes. Historical controls indicate that over half of all pituitary patients would be eligible. Further refinement of patient selection for less costly perioperative management may reduce cost burden for the health care system and patients.

The Effect of Hospital Transfer on Patient Outcomes After Rehabilitation for Spinal Injury.

OBJECTIVE: Spine fractures, including associated spinal cord injury, account for 3%-6% of all skeletal fractures annually in the United States. Patients who undergo interhospital transfer after injury may have a greater likelihood of nonroutine disposition, longer hospital stay, and higher cost. We evaluated the effects of patient transfer on functional outcomes after spine trauma. METHODS: Patients were treated after acute traumatic spine injury at a rehabilitation hospital in 2011-2017. Compared patients were those directly admitted to the tertiary hospital or transferred from a community hospital. RESULTS: A total of 188 patients (mean age 46.1 ± 18.6 years, 77.1% men) were evaluated, including 130 (69.1%) directly admitted and 58 (30.9%) transferred patients. The most common levels of injury were at C5 (19.1%) and C6 (12.2%), and most injuries were American Spinal Injury Association injury severity score grade D (33.2%) or grade A (32.1%). No statistical difference in age, injury pattern, timing from injury to surgery, or rehabilitation length of stay was seen between admitted and transferred patients. A significant improvement in ambulation distances was seen at discharge for directly admitted compared with transferred patients (447.7 ± 724.9 vs. 159.9 ± 359.5 feet; P = 0.005). However, no significant difference primary outcomes, namely American Spinal Injury Association injury severity score distribution (P = 0.2) or Functional Independence Measures (Δ30.9 ± 15.9 vs. 30.1 ± 17.1; P = 0.7), were seen between admitted and transferred patients at time of rehabilitation discharge. CONCLUSIONS: Interhospital transfer status did not diminish time to rehabilitation after injury or reduce functional recovery, suggesting early surgical treatment in community settings may have merit prior to transfer.

Cost Analysis of Inpatient Rehabilitation after Spinal Injury: A Retrospective Cohort Analysis.

Objective The lifetime direct and indirect costs of spinal injury and spinal cord injury (SCI) increase as the severity of injury worsens. Despite the potential for substantial improvement in function with acute rehabilitation, the factors affecting its cost have not yet been evaluated. We used a proprietary hospital database to evaluate the direct costs of rehabilitation after spine injury. Methods A single-center, retrospective cohort cost analysis of patients with acute, traumatic spine injury treated at a tertiary facility from 2011 to 2017 was performed. Results In the 190 patients (mean age 46.1 ± 18.6 years, 76.3% males) identified, American Spinal Injury Association impairment scores on admission were 32.1% A, 14.7% B, 14.7% C, 33.2% D, and 1.1% E. Surgical treatment was performed in 179 (94.2%) cases. Most injuries were in the cervical spine (53.2%). A mean improvement of Functional Impairment Score of 30.7 ± 16.2 was seen after acute rehabilitation. Costs for care comprised facility (86.5%), pharmacy (9.2%), supplies (2.0%), laboratory (1.5%), and imaging (0.8%) categories. Injury level, injury severity, and prior inpatient surgical treatment did not affect the cost of rehabilitation. Higher injury severity (p = 0.0001, one-way ANOVA) and spinal level of injury (p = 0.001, one-way ANOVA) were associated with higher length of rehabilitation stay in univariate analysis. However, length of rehabilitation stay was the strongest independent predictor of higher-than-median cost (risk ratio = 1.56, 95% CI 1.21-2.0, p = 0.001) after adjusting for other factors. Conclusions Spine injury has a high upfront cost of care, with greater need for rehabilitation substantially affecting cost. Improving the efficacy of rehabilitation to reduce length of stay may be effective in reducing cost.