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Intimal sarcomas are rare and histologically heterogeneous tumors, commonly arising from the pulmonary arteries. They have remained challenging to treat. Few studies in the literature study the genomics of this cancer. Identifying targetable alterations is an important step in advancing the treatment of intimal sarcomas. Using data from the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange (AACR GENIE) database, we cataloged genetic alterations and assessed their clinical utility from thirteen patients with intimal sarcoma. Notable copy number alterations included amplification in MDM2, CDK4, PDGFRA, and NOTCH2, as well as copy number losses in CDKN2A and CDKN2B. Actionable alterations included mutations in ATM/ATR, PTCH1, and PDGFRB. Moreover, genomic rearrangement events, specifically PDE4DIP-NOTCH2 and MRPS30-ARID2 fusions were identified. Co-occurring alterations included a NOTCH2 copy number gain in the PDE4DIP-NOTCH2 fusion positive tumor and PDGFRB mutations in both fusion-positive cases. Our study suggests that PDGFRB may be relevant in the tumorigenesis process. Including genomic profiling in the management of intimal sarcoma and potential enrollment in targeted therapy trials is warranted.

e14121 Background: Various immune-related adverse events (IRAE) have been reported with the use of immune checkpoint inhibitors (ICI). Although a rare event, the increasing incidence of ICI related myocarditis and its reported high mortality raises concern. Cardiovascular IRAE such as pericardial effusions (PE) have been documented in case reports and case series but their clinical significance is unclear. Methods: Retrospective chart review was performed on 1075 patients receiving ICI between 2015 and 2017 with baseline echocardiograms without pericardial effusions and follow up echocardiograms at MD Anderson Cancer Center. We collected baseline characteristics, laboratory findings, echocardiograms, and dates of ICI initiation, PE development, last follow up and death. Overall survival (time from first ICI therapy to death or last follow up) was calculated. Univariate Fine-Gray regression analyses were conducted to identify variables associated with PE to account for death as a competing risk event. A p-value of less than 0.05 indicated statistical significance. Results: After initiation of ICI, 78 patients (7.3%) developed PE of which 45 patients died (58%) compared to 347 deaths (35%) out of the 997 patients without PE. The median follow-up time was 445 days. Univariate Fine-Gray analyses predicting PE demonstrated lower body surface area, lowest nadir in left ventricular ejection fraction (LVEF), higher troponin levels, lower platelet counts, absence of ectopy and hyperlipidemia, and lack of avelumab in therapy as well as a history of heart failure with preserved or reduced ejection fraction, hematologic cancer, and peripheral artery stents were significantly associated with higher incidence of PE. Conclusions: While the development of PE is an IRAE or progression of cancer itself cannot be determined, this study indicates patients receiving ICI who developed PE had higher mortality. Those with greater troponin levels and substantial decline in LVEF were shown to have a greater propensity of developing PE, suggesting the possibility of an underlying myopericarditis. If PE develops during ICI therapy, providers should consider an expedited workup and treatment of ICI related myocarditis.

e23097 Background: Doxorubicin and trastuzumab have been described to cause clinical heart failure and asymptomatic declines in left ventricular ejection fraction (LVEF). Initial studies of doxorubicin in the 1970’s defined cardiotoxicity by the clinical syndrome of heart failure without imaging for LVEF determination. Trials with adjuvant trastuzumab used various LVEF cut-offs that were arbitrarily determined. This study aims to compare the predictive value of commonly used definitions of cardiotoxicity associated with chemotherapy for the development of clinical heart failure. Methods: A retrospective chart review was performed on an IRB approved cohort of 638 patients with breast cancer who received doxorubicin, trastuzumab, or both and who had baseline and follow up echocardiograms, collecting LVEF values for each echocardiogram. Clinical heart failure was determined by formal cardiology evaluations denoting clinical heart failure in patients. Four different definitions of cardiotoxicity were compared; American Society of Echocardiography (ASE), Cardiac Review and Evaluation Committee (CREC), Alexander et al, and Schwartz et al (Table). Results: Only 8 patients (1.25%) developed clinical heart failure. The sensitivity, specificity, positive predictive value, and negative predictive value of each definition of cardiotoxicity are listed in the table. Conclusions: Overall there is a low threshold for detection of clinical heart failure in breast cancer therapy. While the ASE definition has the highest combination of sensitivity, specificity, and positive predictive value, it has a sensitivity of only 62.5%. Thus, cardiologists and oncologists should collaborate to develop a definition of cardiotoxicity better correlated to clinical outcomes. [Table: see text]