Bettegowda, Chetan

Real-time intraoperative delineation of cancer and non-cancer brain tissues, especially in the eloquent cortex, is critical for thorough cancer resection, lengthening survival, and improving quality of life. Prior studies have established that thresholding optical attenuation values reveals cancer regions with high sensitivity and specificity. However, threshold of a single value disregards local information important to making more robust predictions. Hence, we propose deep convolutional neural networks (CNNs) trained on labeled OCT images and co-occurrence matrix features extracted from these images to synergize attenuation characteristics and texture features. Specifically, we adapt a deep ensemble model trained on 5,831 examples in a training dataset of 7 patients. We obtain 93.31% sensitivity and 97.04% specificity on a holdout set of 4 patients without the need for beam profile normalization using a reference phantom. The segmentation maps produced by parsing the OCT volume and tiling the outputs of our model are in excellent agreement with attenuation mapping-based methods. Our new approach for this important application has considerable implications for clinical translation.

Abstract BACKGROUND Glioblastoma (GBM) has dismal outcome of 14-16 months. One of the challenges of drug development in GBM is lack of requisite circulating-free (cfDNA) in blood samples to develop biomarker driven targeted therapy trials. The Exablate focused ultrasound with circulating microbubble resonators uses the concept of real-time imaging to treat small target spots focusing energy in a non-invasive manner, thereby disrupting the Blood-Brain Barrier (BBBD) with potential to increase cfDNA in blood. METHODS LIBERATE is a prospective, multi-center, self-controlled pivotal ongoing clinical trial in subjects with suspected GBM evaluating the safety and effectiveness of Exablate Model 4000 to disrupt BBB to achieve a greater proportion of cfDNA in samples taken post-BBB disruption as compared to the sample taken before BBBD. Fifty eligible subjects with suspected GBM who are scheduled to undergo brain tumor resection or biopsy at 10 centers in the U.S. will participate in this study. The primary endpoint is defined for each subject as ratio between his/her cfDNA amount found in the blood sample 1-hour post-BBBD procedure compared to the cfDNA amount found in the blood sample collected pre-BBBD procedure. This study proposes to demonstrate that on average there is at least 2-fold increase in cfDNA (measured by central laboratory) at 1 hour post BBBD. Confirmatory secondary analysis will evaluate correlation between patterns obtained in panel of biomarkers evaluated in the resected tumor tissue and/or biopsy sample and blood sample collected 1-hour post-BBBD. Exploratory endpoints will include: (1) sensitivity of detection of known somatic mutations in the circulating blood samples (circulating tumor DNA) before and after BBBD, (2) time of greatest yield of cfDNA in the samples collected post BBBD blood samples (at 30 min, 1-hour, 2-hour and 3-hour) to determine time of greatest yield, (3) correlation of biomarkers between the imaging and the post-BBBD biomarker samples. (NCT05383872)

PURPOSE Patients with progressive or recurrent meningiomas have limited systemic therapy options. Focal adhesion kinase (FAK) inhibition has a synthetic lethal relationship with NF2 loss. Given the predominance of NF2 mutations in meningiomas, we evaluated the efficacy of GSK2256098, a FAK inhibitor, as part of the first genomically driven phase II study in recurrent or progressive grade 1-3 meningiomas. PATIENTS AND METHODS Eligible patients whose tumors screened positively for NF2 mutations were treated with GSK2256098, 750 mg orally twice daily, until progressive disease. Efficacy was evaluated using two coprimary end points: progression-free survival at 6 months (PFS6) and response rate by Macdonald criteria, where PFS6 was evaluated separately within grade-based subgroups: grade 1 versus 2/3 meningiomas. Per study design, the FAK inhibitor would be considered promising in this patient population if either end point met the corresponding decision criteria for efficacy. RESULTS Of 322 patients screened for all mutation cohorts of the study, 36 eligible and evaluable patients with NF2 mutations were enrolled and treated: 12 grade 1 and 24 grade 2/3 patients. Across all grades, one patient had a partial response and 24 had stable disease as their best response to treatment. In grade 1 patients, the observed PFS6 rate was 83% (10/12 patients; 95% CI, 52 to 98). In grade 2/3 patients, the observed PFS6 rate was 33% (8/24 patients; 95% CI, 16 to 55). The study met the PFS6 efficacy end point both for the grade 1 and the grade 2/3 cohorts. Treatment was well tolerated; seven patients had a maximum grade 3 adverse event that was at least possibly related to treatment with no grade 4 or 5 events. CONCLUSION GSK2256098 was well tolerated and resulted in an improved PFS6 rate in patients with recurrent or progressive NF2-mutated meningiomas, compared with historical controls. The criteria for promising activity were met, and FAK inhibition warrants further evaluation for this patient population.

OBJECTIVE Suprasellar meningioma resection via either the transcranial approach (TCA) or the endoscopic endonasal approach (EEA) is an area of controversy and active evaluation. Skull base surgeons increasingly consider patient-reported outcomes (PROs) when choosing an approach. No PRO measure currently exists to assess quality of life for suprasellar meningiomas. METHODS Adult patients undergoing suprasellar meningioma resection between 2013 and 2019 via EEA (n = 14) or TCA (n = 14) underwent semistructured interviews. Transcripts were coded using a grounded theory approach to identify themes as the basis for a PRO measure that includes all uniquely reported symptoms. To assess content validity, 32 patients and 15 surgeons used a Likert scale to rate the relevance of items on the resulting questionnaire and the general Patient-Reported Outcomes Measurement Information System–29 (PROMIS29). The mean scores were calculated for all items and compared for TCA versus EEA patient cohorts by using unpaired t-tests. Items on either questionnaire with mean scores ≥ 2.0 from patients were considered meaningful and were aggregated to form the novel Suprasellar Meningioma Patient-Reported Outcome Survey (SMPRO) instrument. RESULTS Qualitative analyses resulted in 55 candidate items. Relative to patients who underwent the EEA, those who underwent the TCA reported significantly worse future outlook before surgery (p = 0.01), tiredness from medications 2 weeks after surgery (p = 0.001), and word-finding and memory difficulties 3 months after surgery (p = 0.05 and < 0.001, respectively). The items that patients who received a TCA were most concerned about included medication-induced lethargy after surgery (2.9 ± 1.3), blurry vision before surgery (2.7 ± 1.5), and difficulty reading due to blurry vision before surgery (2.7 ± 2.7). Items that patients who received an EEA were most concerned about included blurry vision before surgery (3.5 ± 1.3), difficulty reading due to blurry vision before surgery (2.4 ± 1.3), and problems with smell postsurgery (2.9 ± 1.3). Although surgeons overall overestimated how concerned patients were about questionnaire items (p < 0.0005), the greatest discrepancies between patient and surgeon relevance scores were for blurry vision pre- and postoperatively (p < 0.001 and < 0.001, respectively) and problems with taste postoperatively (p < 0.001). Seventeen meningioma-specific items were considered meaningful, supplementing 8 significant PROMIS29 items to create the novel 25-item SMPRO. CONCLUSIONS The authors developed a disease- and approach-specific measure for suprasellar meningiomas to compare quality of life by operative approach. If demonstrated to be reliable and valid in future studies, this instrument may assist patients and providers in choosing a personalized surgical approach.

Abstract Background There is an extensive literature highlighting the utility of blood-based liquid biopsies in several extracranial tumors for diagnosis and monitoring. Methods The RANO (Response Assessment in Neuro-Oncology) group developed a multidisciplinary international Task Force to review the English literature on liquid biopsy in gliomas focusing on the most frequently used techniques, that is circulating tumor DNA, circulating tumor cells, and extracellular vesicles in blood and CSF. Results ctDNA has a higher sensitivity and capacity to represent the spatial and temporal heterogeneity in comparison to circulating tumor cells. Exosomes have the advantages to cross an intact blood-brain barrier and carry also RNA, miRNA, and proteins. Several clinical applications of liquid biopsies are suggested: to establish a diagnosis when tissue is not available, monitor the residual disease after surgery, distinguish progression from pseudoprogression, and predict the outcome. Conclusions There is a need for standardization of biofluid collection, choice of an analyte, and detection strategies along with rigorous testing in future clinical trials to validate findings and enable entry into clinical practice.

Study Design: International multicenter prospective observational cohort study on patients undergoing radiation +/− surgical intervention for the treatment of symptomatic spinal metastases. Objectives: To investigate the association between the total Spinal Instability Neoplastic Score (SINS), individual SINS components and PROs. Methods: Data regarding patient demographics, diagnostics, treatment, and PROs (SF-36, SOSGOQ, EQ-5D) was collected at baseline, 6 weeks, and 12 weeks post-treatment. The SINS was assessed using routine diagnostic imaging. The association between SINS, PRO at baseline and change in PROs was examined with the Spearmans rank test. Results: A total of 307 patients, including 174 patients who underwent surgery+/− radiotherapy and 133 patients who underwent radiotherapy were eligible for analyses. In the surgery+/− radiotherapy group, 18 (10.3%) patients with SINS score between 0-6, 118 (67.8%) with a SINS between 7-12 and 38 (21.8%) with a SINS between 13-18, as compared to 55 (41.4%) SINS 0-6, 71(53.4%) SINS 7-12 and 7 (5.2%) SINS 13-18 in the radiotherapy alone group. At baseline, the total SINS and the presence of mechanical pain was significantly associated with the SOSGOQ pain domain (r = −0.519, P < 0.001) and the NRS pain score (r = 0.445, P < 0.001) for all patients. The presence of mechanical pain demonstrated to be moderately associated with a positive change in PROs at 12 weeks post-treatment. Conclusion: Spinal instability, as defined by the SINS, was significantly correlated with PROs at baseline and change in PROs post-treatment. Mechanical pain, as a single SINS component, showed the highest correlations with PROs.

OCT-based quantitative tissue optical properties imaging is a promising technique for intraoperative brain cancer assessment. The attenuation coefficient analysis relies on the depth-dependent OCT intensity profile, thus sensitive to tissue surface positions relative to the imaging beam focus. However, it is almost impossible to maintain a steady tissue surface during intraoperative imaging due to the patient’s arterial pulsation and breathing, the operator’s motion, and the complex tissue surface geometry of the surgical cavity. In this work, we developed an intraoperative OCT imaging probe with a surface-tracking function to minimize the quantification errors in optical attenuation due to the tissue surface position variations. A compact OCT imaging probe was designed and engineered to have a long working distance of ∼ 41 mm and a large field of view of 4 × 4 mm2 while keeping the probe diameter small (9 mm) to maximize clinical versatility. A piezo-based linear motor was integrated with the imaging probe and controlled based upon real-time feedback of tissue surface position inferred from OCT images. A GPU-assisted parallel processing algorithm was implemented, enabling detection and tracking of tissue surface in real-time and successfully suppressing more than 90% of the typical physiologically induced motion range. The surface-tracking intraoperative OCT imaging probe could maintain a steady beam focus inside the target tissue regardless of the surface geometry or physiological motions and enabled to obtain tissue optical attenuation reliably for assessing brain cancer margins in challenging intraoperative settings.

OBJECTIVE Oncological resection of primary spine tumors is associated with lower recurrence rates. However, even in the most experienced hands, the execution of a meticulously drafted plan sometimes fails. The objectives of this study were to determine how successful surgical teams are at achieving planned surgical margins and how successful surgeons are in intraoperatively assessing tumor margins. The secondary objective was to identify factors associated with successful execution of planned resection. METHODS The Primary Tumor Research and Outcomes Network (PTRON) is a multicenter international prospective registry for the management of primary tumors of the spine. Using this registry, the authors compared 1) the planned surgical margin and 2) the intraoperative assessment of the margin by the surgeon with the postoperative assessment of the margin by the pathologist. Univariate analysis was used to assess whether factors such as histology, size, location, previous radiotherapy, and revision surgery were associated with successful execution of the planned margins. RESULTS Three hundred patients were included. The surgical plan was successfully achieved in 224 (74.7%) patients. The surgeon correctly assessed the intraoperative margins, as reported in the final assessment by the pathologist, in 239 (79.7%) patients. On univariate analysis, no factor had a statistically significant influence on successful achievement of planned margins. CONCLUSIONS In high-volume cancer centers around the world, planned surgical margins can be achieved in approximately 75% of cases. The morbidity of the proposed intervention must be balanced with the expected success rate in order to optimize patient management and surgical decision-making.

Abstract Background Chordomas are the most common primary spinal column malignancy in the United States. The aim of this study was to determine whether chordomas may be detected by evaluating mutations in circulating tumor DNA (ctDNA). Methods Thirty-two patients with a biopsy-confirmed diagnosis of chordoma had blood drawn pre-operatively and/or at follow-up appointments. Mutations in the primary tumor were identified by whole exome sequencing and liquid biopsy by ddPCR and/or RACE-Seq was used to detect one or more of these mutations in plasma ctDNA at concurrent or later time points. Results At the time of initial blood draw, 87.1% of patients were ctDNA positive (P &lt;.001). Follow-up blood draws in twenty of the patients suggest that ctDNA levels may reflect the clinical status of the disease. Patients with positive ctDNA levels were more likely to have greater mutant allele frequencies in their primary tumors (P = .004) and undergo radiotherapy (P = .02), and the presence of ctDNA may correlate with response to systemic chemotherapy and/or disease recurrence. Conclusions Detection of ctDNA mutations may allow for the detection and monitoring of disease progression for chordomas.

Abstract BACKGROUND Despite our inability to accurately predict survival in many cancer patients, a life expectancy of at least 3 mo is historically necessary to be considered for surgical treatment of spinal metastases. OBJECTIVE To compare health-related quality of life (HRQOL) in patients surviving <3 mo after surgical treatment to patients surviving >3 mo to assess the validity of this inclusion criteria. METHODS Patients who underwent surgery for spinal metastases between August 2013 and May 2017 were retrospectively identified from an international cohort study. HRQOL was evaluated using generic and disease-specific outcome tools at baseline and at 6 and 12 wk postsurgery. The primary outcome was the HRQOL at 6 wk post-treatment measured by the Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ). RESULTS A total of 253 patients were included: 40 patients died within the first 3 mo after surgery and 213 patients survived more than 3 mo. Patients surviving <3 mo after surgery presented with lower baseline performance status. Adjusted analyses for baseline performance status did not reveal a significant difference in HRQOL between both groups at 6 wk post-treatment. No significant difference in patient satisfaction at 6 wk with regard to their treatment could be detected between both groups. CONCLUSION When controlled for baseline performance status, quality of life 6 wk after surgery for spinal metastasis is independent of survival. To optimize improvement in HRQOL for this patient population, baseline performance status should take priority over expected survival in the surgical decision-making process.