The limited effectiveness of conventional therapy for malignant pleural mesothelioma demands innovative approaches to this difficult disease. Even with aggressive multimodality treatment of surgery, radiation, and/or chemotherapy, the median survival is only 1–2 years depending on stage and histology. Oncolytic viral therapy has emerged in the last several decades as a rapidly advancing field of immunotherapy studied in a wide spectrum of malignancies. Mesothelioma makes an ideal candidate for studying oncolysis given the frequently localized pattern of growth and pleural location providing access to direct intratumoral injection of virus. Therefore, despite being a relatively uncommon disease, the multitude of viral studies for mesothelioma can provide insight for applying such therapy to other malignancies. This article will begin with a review of the general principles of oncolytic therapy focusing on antitumor efficacy, tumor selectivity, and immune system activation. The second half of this review will detail results of preclinical models and human studies for oncolytic virotherapy in mesothelioma.

e20520 Background: Studies have suggested that antibiotics can negatively influence efficacy of immune check-point blockers (ICB) but the results are inconsistent. The impact of concomitant proton pump inhibitors (PPI) is not known. We evaluated whether antibiotic and PPI use in patients with advanced non-small-cell lung cancer (NSCLC) and metastatic renal cell cancer (RCC) affects ICB efficacy. Methods: We identified advanced NSCLC and RCC patients treated with anti-PD1/PD-L1 at our institution between 5/2015 to 1/2019. Data regarding systemic antibiotics and PPI use < 1 month or during ICB treatment were collected. The primary outcome was progression free survival (PFS) per response evaluation criteria in solid tumors (RECIST 1.1). Secondary outcomes were overall survival (OS) and objective response rate (ORR). Logistic regression and cox proportional hazards model were used for statistical analysis. Results: 87/148 (58%) and 40/55 (72%) patients received antibiotics and 57/148 (39%) and 17/55 (31%) received PPI < 1 month or during ICI therapy in NSCLC and RCC respectively. In RCC, antibiotic use was associated with inferior PFS (2.9 v 5.0 months, HR = 2.3 95%CI 1.0-5.0; p = 0.04) but OS and ORR were not affected. In NSCLC, antibiotic exposure was associated with superior PFS (5.0 v 2.5 months, HR = 0.5, 95% CI 0.3-0.7; p < 0.01), OS (13.0 v 8.0 months, HR = 0.5, 95% CI 0.3-0.8; p < 0.01) and ORR (33% v 11%, OR = 4.6, p < 0.01). On univariate analysis, there was trend towards inferior OS in NSCLC (9.0 v 13.0 months, p = 0.05) with PPI use. PPI use was not associated with other primary or secondary outcomes in both the cohorts. The antibiotic effect remained significant for PFS in NSCLC and RCC in multivariate analysis. Conclusions: Antibiotic use significantly affected PFS in both NSCLC and RCC. PPI use did not affect outcomes. In contrast to previous studies, this is the first study to show that antibiotic use was associated with favorable outcomes in NSCLC. More studies are needed to explain this association. Future clinical trials with ICB should consider stratification of patients based on antibiotic exposure.

Background: Immune checkpoint inhibitors (ICIs) have changed the treatment paradigm of advanced-stage non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). The aim of this study was to evaluate the effectiveness and tolerance of ICIs in a real-world patient population and to investigate the predictive factors associated with survival outcomes. Methods: Medical records of patients with advanced lung cancer who started ICI monotherapy were reviewed for data collection. Treatment outcomes included objective response rate, progression-free survival (PFS), and overall survival (OS). Immune-related adverse events (irAEs) were assessed. Multiple Cox regression models were fit to investigate the predictive factors for survival outcomes. Results: We included 220 patients (median 66.5 years). Seventy-nine (35.9%) patients had Eastern Cooperative Oncology Group (ECOG) performance-status (PS) score ⩾2. Median follow-up was 11.4 months. In NSCLC, median PFS was 3.8 months (4.7 months for first line and 3.7 months for subsequent line). Median OS was 12.4 months (15.6 months for first line therapy and 11.5 months for subsequent line). In SCLC, median PFS was 1.8 months, and median OS was 4.6 months. A quarter of patients developed irAEs. There was 1 disease flare among 17 patients with pre-existing autoimmune diseases. ECOG PS of 0 to 1 and body mass index (BMI) ⩾ 25 kg/m2 (but not occurrence of irAE) were independently associated with improved OS in NSCLC, with a hazard ratio of 0.41 (95% confidence interval [CI], 0.29-0.59) and 0.62 (95% CI, 0.44-0.87), respectively. Conclusions: The clinical benefit of ICIs appears to persist in a real-world population of relatively older age, including those with poor PS and pre-existing autoimmune diseases. ECOG PS of 0 to 1 and BMI ⩾ 25 kg/m2 were independently associated with improved OS.

Purpose The heterogeneous nature of myelodysplastic syndromes (MDS) complicates therapeutic decision making, particularly for newly diagnosed disease. Factors impacting the treatment plan in this early period of disease course are poorly defined. This study determines whether therapeutic choices for newly diagnosed MDS are associated with location of treatment (community or academic), prognostic risk category, and patient age. Methods The Adults in Minnesota with Myelodysplastic Syndromes (AIMMS) database was utilized in this statewide, prospective population-based study conducted by the University of Minnesota (UMN), Mayo Clinic, and Minnesota Department of Health. Adult (age 20+ years) cases of MDS newly diagnosed starting in April 2010 were invited to participate. This analysis includes patients enrolled during the first study year with one-year follow-up data. Treatment choices (supportive, active, and transplant) were stratified by the international prognostic scoring system (IPSS) and the revised-IPSS (IPSS-R), then separated into groups by location of care and age (<65 or 65+ years). Academic-based care was any contact with the UMN and Mayo Clinic; community-based care was all other clinical sites. Results Stratification by IPSS and IPSS-R showed supportive care decreased and active care increased with advancing risk categories (p <0.0001). Comparing treatment setting, community-based care had 77% supportive and 23% active treatment; academic-based care was 36% supportive, 41% active, and 23% transplant (p <0.0001). By age groups, patients <65 years with intermediate, high, or very high risk disease by IPSS-R received 97% active care/transplant, compared to only 52% of patients age 65+. Conclusions Younger patients and those treated at academic centers had a more aggressive treatment approach. Whether these treatment differences convey improved disease control and mortality, and therefore should be extended more frequently to older and community-based patients, is the subject of ongoing prospective study.

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Background: The Yt system consists of five antigens: antithetical Yt a /Yt b and the high-prevalence antigens YTEG, YTLI, and YTOT. We investigated a sample from a Native American (NA) female with post-operative anemia and an unidentified antibody who developed rigors, tachycardia, and hypotension on transfusion of incompatible RBCs.Methods and Materials: Serologic testing methods included LISS, PEG, and IgG gel. Test RBCs were treated with papain, trypsin, alpha-chymotrypsin, 2-amino-ethylisothiouronium, and dithiothreitol. Rare RBCs were tested, and inhibition studies were performed. DNA extracted from WBCs was used for Sanger sequencing.Results: Initial testing showed strong 3-4+ plasma reactivity with all panel cells at LISS IAT; auto control was negative. Positive reactions were observed with numerous rare RBCs except for PNH-III, which lack GPI-linked DO, Yt, CROM, JMH, and Emm. Enzyme sensitivity patterns suggest Yt specificity, and soluble recombinant srYt neutralized reactivity. ACHE sequencing revealed YT*A/A genotype but with a homozygous change in exon 2, c.290A>G (p.Gln97Arg). Antibody reactivity was reminiscent of that seen in an unrelated NA male investigated previously. His RBCs were nonreactive with her plasma. ACHE carried the same c.290G/G change. Conclusion:Two unrelated NA patients were found to have an antibody to a new high-prevalence Yt antigen, designated YTGT (YT6), associated with a clinically significant transfusion reaction. Identification of the specificity relied on enzyme sensitivity, use of PNH-III RBCs, neutralization using soluble recombinant Yt, and the finding of a novel change in ACHE, c.290A>G (p.Gln97Arg), designated YT*01.-06. IVIG and steroids were used to mitigate further reactions to transfusion.

5051 Background: Prostate specific antigen (PSA) screening for prostate cancer has declined following the USPSTF 2012 recommendation. How screening rates and prostate cancer diagnoses have subsequently changed in a racially diverse patient population is not well defined. In this study, we aim to determine the impact of the USPSTF screening recommendation in the Hennepin Healthcare System (HHS) in the state of Minnesota. Methods: A single-institution retrospective analysis of data from our electronic health record, to identify the characteristics of PSA screening and new prostate cancer diagnoses for men ≥50 years between 2008 and 2015. Data before and after May 2012 were compared. P-values were calculated using binominal and generalized linear models. Results: Nearly 22,000 patients underwent PSA screening from 2008 to 2015. PSA screening rates decreased after May 2012 for the four largest demographics represented (p < 0.001). Hispanics and Blacks were more likely to be screened when compared to Whites and Asians (p < 0.05). 319 cases of prostate cancer were diagnosed from 2008 to 2015 with 87 cases (27.3%) diagnosed by PSA-screening. The number needed to screen to diagnose one patient with prostate cancer at HHS was 137.5, and 9.5% of patients (1146 patients) had a false positive PSA that led to further testing or a biopsy. $56,090 was spent in screening costs per diagnosis of early stage prostate cancer via screening. Patients diagnosed from screening were less likely to present with high Gleason scores (8-10) compared to non-screening diagnosis (8% vs 23.3%, p < 0.01). The 5-year survival percentage (prostate cancer mortality) was improved for those patients diagnosed by PSA screening vs the non-screened group (100% vs 89.3%, p < 0.05). Conclusions: PSA screening has declined at HHS since the USPSTF recommendation against prostate cancer screening. Implementation of PSA screening in our healthcare system is expensive and leads to a high number of false positives. Despite this, the 5-year survival from prostate cancer is significantly higher when patients are diagnosed by PSA screening.

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