Correlation of clinical outcomes with programmed death ligand-1 expression on liquid biopsy

e21050

Background: Programmed death ligand-1 (PD-L1) expression is predictive of immunotherapy benefit. However, tissue PD-L1 protein immunohistochemical testing can be fraught with tissue acquisition and heterogeneity limitations. PD-L1 expression by RNA sequencing can be performed by both tissue and plasma with tissue PD-L1 protein correlations. What has not been well characterized is the correlation of plasma cell free circulating tumor RNA (cfRNA) PD-L1 and clinical outcomes with immunotherapy. Plasma cfRNA PD-L1 expression was evaluated and correlated with immunotherapy benefit in advanced non-small cell lung cancers (NSCLC). Methods: Patients with advanced NSCLC undergoing plasma next-generation sequencing including plasma cfRNA.PD-L1 testing in a Clinical Laboratory Improvement Amendments (CLIA) and College of American pathologists (CAP) accredited laboratory were retrospectively identified and evaluated at a single institution. Plasma PD-L1 positive patients underwent a de-identified chart abstraction to identify those patients with advanced NSCLC treated with front line immunotherapy regimens and those who received cytotoxic chemotherapy alone. Results: Sixteen patients with plasma PD-L1 expression treated with front-line immunotherapy regimens including single-agent immune checkpoint inhibitors, and combinatorial chemo-immune or chemo-immune-bevacizumab regimens were assessed for overall survival (OS). Eleven patients with plasma PD-L1 expression who received chemotherapy were used as a non-immunotherapy OS comparison. Median OS for the immunotherapy treated patients was thirteen months with a thirty percent three year landmark OS versus four months median OS and a ten percent three-year landmark OS for those treated with chemotherapy alone. Comparative log-rank test p-value 0.0091 and a hazard ratio of 0.36 (95%-CI 0.13-0.99). Conclusions: Plasma cfRNA PD-L1 expression is predictive of a statistically significant survival benefit from immunotherapy treatment compared to chemotherapy in the first line treatment of advanced NSCLC. The three year landmark OS of thirty percent parallels tissue PD-L1 directed immunotherapy-based treatment outcomes. The clinical utility of plasma cfRNA PD-L1 to overcome tissue acquisition and PD-L1 protein heterogeneity limitations and to study the dynamic nature of PD-L1 expression with non-immune cancer treatments and potential immunotherapy response monitoring are undergoing ongoing research.

Racial variation in molecular profile of advanced gastrointestinal cancers

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Background: Heterogeneity in the tumor molecular profile based on race is poorly understood. We sought to review the utilization of next generation sequencing (NGS) in patients with advanced gastrointestinal (GI) malignancies treated at a rural academic center and analyze inter racial variations in the molecular tumor profile. Methods: We conducted a retrospective review of patients with advanced GI malignancies that underwent NGS between 2015 to 2018 at East Carolina University.104 patients met eligibility criteria but 8 patients were excluded due to insufficient tissue sampling. Patients with colorectal, gastric, pancreatic, biliary, small intestinal and esophageal cancers were included. Targeted NGS using Caris Life Sciences¨ platform was performed to obtain molecular analysis. We conducted descriptive univariate analysis, cox regression and Kaplan-Meier survival curve analysis. Results: Median age at diagnosis was 64yrs and 64% of patients were black. The study cohort had 41% (n=39) with colon cancer, 18%(17) gastric cancer, 30% (29) pancreatic cancer, 6%(6) biliary cancer, 4%(4) small intestinal cancer and 1%(1) esophageal cancer. 60% (55) had de novo Stage IV disease. Median overall survival (OS) was 25 months (mo), 30 mo in blacks and 32 mo in whites (p value =0.46). Microsatellite stability was seen in 94% (87) and instability in 3% (3). Overall cohort had mutations (mut) in KRAS (50%), TP53 (64%), BRAF (4%), and ERBB amplification (3%). On the cox regression model APC mutation was associated with worse outcome. Black patients had more alterations in KRAS, TP53 (both not significant), and APC (p=0.02). Conclusions: In our analysis we observed inter racial variations in molecular profile of advanced GI malignancies. Black patients had increased rates of APC, KRAS and TP 53 mut. Further studies are required to analyze the impact of these molecular variations on outcomes. Results.

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Gemella Species Bacteremia and Stroke in an Elderly Patient with Respiratory Tract Infection

Gemella species are part of normal human flora. They are rarely associated with infections. As opportunistic pathogens, they can cause life-threatening infection in individuals with risk factors. We present an unusual case of an elderly patient, with no predisposing risk factors, who presented with respiratory tract infection and Gemella species bacteremia and suffered a stroke in the absence of features of endocarditis.