LMD-15. Beyond cytologY - A single institution experience using CNSideTM for diagnosing and monitoring treatment response in Non-Small Cell Lung Cancer patients with Leptomeningeal Carcinomatosis (LMC)

Introduction Leptomeningeal Carcinomatosis (LMC) occurs in 3–9% of Non-Small Cell Lung Cancer (NSCLC) patients. Diagnosis of LMC includes clinical evaluation, imaging, and cytology. These have modest sensitivity and are inadequate for monitoring treatment response. Biocept’s CNSideTM is a proprietary assay utilizing a 10-antibody capture cocktail with microfluidic chamber that quantitatively detects tumor cells in the cerebrospinal fluid (CSF). Switch BlockerTM is a proprietary single gene assay that detects actionable mutations in the CSF. We describe a retrospective single institution experience using these assays in NSCLC patients with confirmed LMC or suspected LMC, treated between 2017 and 2021. Methods For fresh samples, CNSide and cytology were used to detect tumor cells, NGS and Switch Blocker was used to detect actionable mutations. Frozen samples were analyzed by NGS and/or Switch Blocker assays. Results CSF was collected from 30 samples (16 unique patients), of which frozen (8 unique patients) and fresh samples (8 unique patients; 5 with and 3 without LMC). CNSide detected tumor cells in 100% samples (10/10) vs cytology in 40% samples (4/10). Of those without LMC, neither CNSide nor cytology identified tumor cells. In patients with serial samples, CNSide tracked the clinical course. Analysis of frozen CSF by NGS identified mutations including EGFR in six (6), ALK in three (3) and BRAF in one (1) patient, which correlated with the primary tumor. The median survival from diagnosis of LMC for those with frozen samples was 71.6 weeks. Conclusion We demonstrate that 1) survival of patients with LMC can be prolonged, especially when an actionable target is identified, 2) CNSide has greater sensitivity in detecting LMC than cytology, and 3) quantitative monitoring of CSF tumor cells can be used to guide initial and subsequent therapies. Larger clinical trials are needed to better establish the utility of CNSide in managing LMC.

Urinary biomarkers for monitoring treatment response in neuroblastoma patients.

e22008 Background: Neuroblastoma is the most common extracranial solid tumor in children. Its heterogeneity may account for the non-uniform response to therapy; thus, accurate predictive biomarkers are required. We focused on urinary biomarkers since urine contains numerous low molecular weight metabolites that can be used as reliable and non-invasive biomarkers. We detected more than 2,000 metabolites by liquid chromatography-mass spectrometry (LC-MS) through a comprehensive analysis of metabolites in urine samples of patients with neuroblastoma and identified potential urinary biomarker candidates using the Wilcoxon rank-sum test and random forest. In this study, the levels of urinary biomarker candidates were compared between the responder and resistant groups to identify urinary biomarkers for monitoring treatment response. Furthermore, their effectiveness was compared with minimal residual disease (MRD) markers, which are currently considered to predict tumor relapse. Methods: Thirty-two patients with neuroblastoma were divided into two groups according to their responsiveness to therapy: the responder group, in which patients had no recurrence (60 urine samples from 24 patients) and the resistant group in which patients had a recurrence or died (18 urine samples from 8 patients). Levels of urinary metabolites (homovanillic acid [HVA], vanillylmandelic acid [VMA], 3-methoxytyramine sulfate [3-MTS], vanillactic acid [VLA], 3-methoxytyrosine [3-MTR]), and MRD markers (TH, PHOX2B, MK) were compared between the two groups during treatment. Results: The levels of five urinary metabolites (HVA, VMA, VLA, 3-MTR, 3-MTS) were significantly increased in the resistant group compared to that in the responder group. Conclusions: This study shows that three novel urinary metabolites (VLA, 3-MTR, 3-MTS) are significantly associated with the recurrence or death from neuroblastoma.

Systematic review and meta-analysis of the reproducibility of patient self-reported joint counts in rheumatoid arthritis

Objective To assess the reproducibility of patient-reported tender and swollen joint counts of RA patients compared to trained clinicians. Methods We conducted a systematic literature review and meta-analysis of studies comparing patient-reported tender and/or swollen joint counts (TJC and SJC) to clinician counts in patients with rheumatoid arthritis. We calculated a pooled summary estimates for correlation. Agreement was compared using a Bland and Altman approach. Results 14 studies were included in the meta-analysis. There were strong correlations between clinician and patient TJC, 0.78 (95% CI: 0.76, 0.80), and clinician and patient SJC, 0.59 (95% CI: 0.54, 0.63). TJC had good reliability ranging from 0.50 to 0.85. SJC had moderate reliability ranging from 0.28 to 0.77. Agreement for TJC reduced for higher TJC values, suggesting a positive bias for self-reported TJC, which was not observed for SJC. Conclusion This meta-analysis has identified a strong correlation for patient-reported and clinician TJC, and a moderate correlation for SJC. Patient-reported joint counts may be suitable for use in annual review for patients in remission and in monitoring treatment response for patients with rheumatoid arthritis. However, they are likely not appropriate for decisions on commencement of biologics. Further research is needed to identify patient groups where patient-reported joint counts are unsuitable.

Highly Specific and Ultrasensitive Plasma Test Detects Abeta(1-42) and Abeta(1-40) in Alzheimer’s Disease

BACKGROUND Plasma biomarkers that reflect specific amyloid beta (Abeta) proteoforms are essential to monitor treatment effects of Alzheimer’s disease (AD) therapies. Our aim was to develop and validate ready-to-use Simoa ‘Amyblood’ assays that measure full length Abeta1-42 and Abeta1-40 and compare their performance with two commercial assays. METHODS Linearity, intra- and inter-assay %CV were compared between Amyblood, Quanterix Simoa triplex, and Euroimmun ELISA. Sensitivity and selectivity were assessed for Amyblood and the Quanterix triplex. Clinical performance was assessed in CSF biomarker confirmed AD (n=43, 68±6 years) and controls (n=42, 62±5 years). RESULTS Prototype and Amyblood showed similar calibrator curves and differentiation (20 AD vs 20 controls, p<0.001). Amyblood, Quanterix triplex, and ELISA showed similar linearity (96%-122%) and intra-assay %CVs (≤3.1%). A minor non-specific signal was measured with Amyblood of +2.4 pg/mL Abeta1-42 when incubated with 60 pg/mL Abeta1-40. A substantial non-specific signal of +24.7 pg/mL Abetax-42 was obtained when 40 pg/mL Abeta3-42 was measured with the Quanterix triplex. Selectivity for Abeta1-42 at physiological Abeta1-42 and Abeta1-40 concentrations was 125% for Amyblood and 163% for Quanterix. Amyblood and Quanterix ratios (p<0.001) and ELISA Abeta1-42 concentration (p=0.025) could differentiate AD from controls. CONCLUSIONS We successfully developed and upscaled a prototype to the Amyblood assays with similar technical and clinical performance as the Quanterix triplex and ELISA, but better specificity and selectivity than the Quanterix triplex assay. These results suggest leverage of this specific assay for monitoring treatment response in trials.