Mesothelin (MSLN) is a differentiation antigen that is highly expressed in many epithelial cancers. MSLN is an important therapeutic target due to its high expression in cancers and limited expression in normal human tissues. Although it has been assumed that shed antigen is a barrier to immunotoxin action, a modeling study predicted that shed MSLN may enhance the action of MSLN-targeting recombinant immunotoxins such as SS1P and similar therapeutics by facilitating their redistribution within tumors. We aimed to determine whether shed MSLN enhances or reduces the antitumor effect of MSLNtargeting immunotoxins SS1P and RG7787. We engineered a cell line, A431/G9 (TACE mutant) that expresses a mutant form of MSLN in which the TNF-converting enzyme protease site is replaced with GGGS. We compared the response of the TACEmutant cells with immunotoxins SS1P and RG7787 with that of the parental A431/H9 cell line. We show that TACE-mutant cells shed 80% less MSLN than A431/H9 cells, that TACE-mutant cells show a 2-to 3-fold increase in MSLN-targeted immunotoxin uptake, and that they are about 5-fold more sensitive to SS1P killing in cell culture. Tumors with reduced shedding respond significantly better to treatment with SS1P and RG7787. Our data show that MSLN shedding is an impediment to the antitumor activity of SS1P and RG7787. Approaches that decrease MSLN shedding could enhance the efficacy of immunotoxins and immunoconjugates targeting MSLN-expressing tumors. Mol Cancer Ther; 15(7); 1648-55. Ó2016 AACR.

<b><i>Introduction:</i></b> Cardiovascular comorbidities may predispose to adverse outcomes in hospitalized patients with coronavirus disease 2019 (COVID-19). However, across the USA, the burden of cardiovascular comorbidities varies significantly. Whether clinical outcomes of hospitalized patients with COVID-19 differ between regions has not yet been studied systematically. Here, we report differences in underlying cardiovascular comorbidities and clinical outcomes of patients hospitalized with COVID-19 in Texas and in New York state. <b><i>Methods:</i></b> We established a multicenter retrospective registry including patients hospitalized with COVID-19 between March 15 and July 12, 2020. Demographic and clinical data were manually retrieved from electronic medical records. We focused on the following outcomes: mortality, need for pharmacologic circulatory support, need for mechanical ventilation, and need for hemodialysis. Univariate and multivariate logistic regression analyses were performed. <b><i>Results:</i></b> Patients in the Texas cohort (<i>n</i> = 296) were younger (57 vs. 63 years, <i>p</i> value &#x3c;0.001), they had a higher BMI (30.3 kg/m² vs. 28.5 kg/m², <i>p</i> = 0.015), and they had higher rates of diabetes mellitus (41 vs. 30%; <i>p</i> = 0.014). In contrast, patients in the New York state cohort (<i>n</i> = 218) had higher rates of coronary artery disease (19 vs. 10%, <i>p</i> = 0.005) and atrial fibrillation (11 vs. 5%, <i>p</i> = 0.012). Pharmacologic circulatory support, mechanical ventilation, and hemodialysis were more frequent in the Texas cohort (21 vs. 13%, <i>p</i> = 0.020; 30 vs. 12%, <i>p</i> &#x3c; 0.001; and 11 vs. 5%, <i>p</i> = 0.009, respectively). In-hospital mortality was similar between the 2 cohorts (16 vs. 18%, <i>p</i> = 0.469). After adjusting for differences in underlying comorbidities, only the use of mechanical ventilation remained significantly higher in the participating Texas hospitals (odds ratios [95% CI]: 3.88 [1.23, 12.24]). Median time to pharmacologic circulatory support was 8 days (interquartile range: 2, 13.8) in the Texas cohort compared to 1 day (0, 3) in the New York state cohort, while median time to in-hospital mortality was 16 days (10, 25.5) and 7 days (4, 14), respectively (both <i>p</i> &#x3c; 0.001). In-hospital mortality was higher in the late versus the early study phase in the New York state cohort (24 vs. 14%, <i>p</i> = 0.050), while it was similar between the 2 phases in the Texas cohort (16 vs. 15%, <i>p</i> = 0.741). <b><i>Conclusions:</i></b> Geographical differences, including practice pattern variations and the impact of disease burden on provision of health care, are important for the evaluation of COVID-19 outcomes. Unadjusted data may cause bias affecting future regulatory policies and proper allocation of resources.

Introduction: Although primarily a respiratory illness, COVID-19 frequently involves the cardiovascular system. Hypothesis: Accordingly, we assessed whether abnormal electrocardiographic findings, including cardiac dysrhythmias, ST/T wave changes, and QTc interval prolongation, predict adverse outcomes in patients with COVID-19. Methods: A multi-center retrospective study of hospitalized patients with COVID-19 was performed across 4 hospitals in Texas and 1 in New York. Initial and subsequent ECG findings among patients with uncomplicated disease course, patients with adverse clinical outcomes (need for vasopressors, mechanical ventilation or renal replacement therapy) and patients who died were analyzed. Univariable and multivariable Cox analyses were performed. Results: We identified 297 consecutive patients with COVID-19. Of these patients, 91% had available ECGs. Median heart rate on initial ECG was 92 bpm (IQR: 27), and median QTc interval was 442 msec (IQR: 40). Longer QTc interval on initial ECG was associated with adverse clinical outcomes (443 msec, IQR: 43) and death (457 msec, IQR: 52, vs 441.5 msec, IQR: 36; p=0.033). Cardiac dysrhythmias or ST/T wave changes were noted in subsequent ECGs of 46% of patients and were associated with adverse clinical outcomes (58%) or death (68% vs 33%; HR: 2.2, 95% CI: 1.3-3.6; p=0.002). Sixty-four patients (23%) developed a QTc interval >500msec during their hospitalization. In multivariable Cox analysis, history of coronary artery disease was independently associated with development of QTc>500msec (HR 2.1, 95% CI 1.0-4.4; p=0.047) while other baseline comorbidities were not. Patients with QTc>500msec were more commonly treated with azithromycin (91% vs 77%; p=0.048); no other differences in COVID-19 treatment were identified. In-hospital mortality among patients with QTc>500msec was 37% versus 13% among patients with shorter QTc intervals (HR: 2.6, 95% CI 1.5-4.5; p=0.001). Conclusions: Prolonged QTc interval on initial ECG of COVID-19 patients predicted adverse outcomes and death. Azithromycin was associated with development of QTc>500msec. Patients with a QTc interval >500msec had a 2.6 times higher risk for in-hospital mortality compared to patients with shorter QTc intervals.