Background The Coronavirus disease-2019 (COVID-19) is a global pandemic caused by novel coronavirus SARS-CoV-2. Acute respiratory and renal failure as well as systemic coagulopathy are critical aspects of the morbidity and mortality in patients with COVID-19. Heparin Induced Thrombocytopenia (HIT) occurs when IgG antibodies form against platelet factor 4-Heparin complex, resulting in platelet activation and removal, leading to a prothrombotic state. HIT is suspected when there is a platelet count decrease of more than 50% after exposure to heparin, along with hypercoagulability. Clinical Scoring systems like 4T Score (Thrombocytopenia, Timing, Thrombosis, no other cause of Thrombocytopenia) have been developed to assess the pretest probability of HIT. The use of unfractionated heparin, post-orthopedic and post-cardiac surgery state, female gender, and old age are recognized as risk factors for HIT. There is a nine-fold increased risk of developing HIT in patients requiring hemodialysis. ICU patients and patients with VTE without thrombocytopenia are considered to have low pre-test probability for HIT. Studies have shown that only 6% who are investigated serologically for HIT actually have the diagnosis. We conducted this study to assess the incidence and risk factors for HIT in COVID-19 positive patients and its impact on mortality. Methods A retrospective analysis was performed on all patients who were COVID-19 positive and hospitalized between March 1, 2020 and June 26, 2020 at our institution. Patients with intermediate or high suspicion for HIT, based on 4T score of 4 or higher, underwent IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA). Washed platelet assays such as serotonin release assay (SRA) and heparin-induced platelet aggregation (HIPA) were used as confirmatory tests in cases with intermediate or low optical density (OD) with EIA. The incidence of HIT, its impact on mortality, and positivity of IgG-specific PF4-EIA in COVID-19 patients were studied, and statistical analysis was done with X2 testing. Subgroup analysis was performed based on demographic factors and risk factors for HIT, including exposure to heparin or low molecular weight heparin (LMWH), history of or cancer, recent orthopedic or cardiac surgery, exposure to renal replacement therapy (RRT), and severity of disease (D-dimer >6 ULN, Acute Kidney Injury, ICU admission, and mechanical ventilation requirement). These factors were analyzed by Fisher's exact test to determine their impact on mortality. The hospital course for HIT antibody-positive patients was further analyzed to study the impact of COVID-19 related therapy, such as Remdesivir, Tocilizumab, Hydroxychloroquine, Steroids, and anticoagulation after diagnosis of HIT. Results WEight out of 1265 hospitalized COVID-19 positive patients tested positive for IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA+). Incidence of EIA+ in COVID-19 patients was 0.6%, which is significantly higher than in the general population 0.2% (p<.0001, 95% CI 0.25-1.20%). The incidence of thromboembolic events in EIA+ patients was 87.5%, significantly higher than the rate of 10.90% in all COVID-19 patients (p<.0001, CI 41.96- 86.98%). The mortality rate in EIA+ patients was 50%, significantly greater than the mortality rate of 12% in all hospitalized COVID-19 patients (p=.0011, CI 9.46-66.53). Serological confirmation of HIT diagnosis was 37.5% (2 had OD>1, 1 was SRA positive) which is significantly higher than confirmation of HIT in nonCOVID-19 patients 6% (p<.0001, 95% CI 29.57-85.32%). All 3 confirmed HIT patients (100%) had severe disease (3/3 required ICU admission, 2/3 required mechanical ventilation, the one not requiring mechanical ventilation required RRT). Conclusion Our study indicates incidence of HIT is higher in the COVID-19 population. The incidence of positive EIA for patients with intermediate to high 4T scores is also higher in COVID-19 positive patients. This can be attributed to the cytokine storm and severe sepsis seen in critically ill COVID-19 patients. Our study also suggests that development of HIT can contribute to increased risk for thromboembolic events as well as mortality of COVID-19 patients, however, our study is limited due to small sample size. Therefore, prospective studies are needed to analyze the impact of HIT on morbidity, mortality and long-term outcomes in COVID-19 patients. Table Disclosures No relevant conflicts of interest to declare.

Background Acute respiratory and renal failure as well as systemic coagulopathy are critical aspects of the morbidity and mortality in patients with COVID-19. Heparin Induced Thrombocytopenia (HIT) occurs when IgG antibodies form against platelet factor 4-Heparin complex, resulting in platelet activation and removal, leading to a prothrombotic state. Studies have shown that only 6% who are investigated serologically for HIT actually have the diagnosis. Methods A retrospective analysis was performed on all COVID-19 positive patients hospitalized between March and June 2020. Patients with suspicion for HIT were tested for HIT antibodies with IgG-specific platelet factor 4(PF4)-dependent enzyme immunoassay (EIA). Confirmatory testing with serotonin release assay (SRA) and heparin-induced platelet aggregation were used in cases with intermediate or low optical density (OD) with EIA positivity (EIA+). Due to rarity of disease, a through literature review on HIT in COVID-19 patients was also analyzed. Results Incidence of EIA + in COVID-19 patients was 0.6%, significantly higher than in the general population 0.2% (p < 0.0001). The incidence of thromboembolic events in EIA + patients was 87.5%, significantly higher than the rate of 10.90% in all COVID-19 patients (p < 0.0001). The mortality rate in EIA + patients was 50%, significantly greater than the mortality rate of 12% in all hospitalized COVID-19 patients (p = 0.0011). Serological confirmation of HIT diagnosis was 37.5% which is significantly higher than confirmation of HIT in nonCOVID-19 patients 6% (p < 0.0001). Of 39 HIT antibody positive patients in the literature, 23.07% had positive confirmatory testing (6 SRA, 3 HIPAA) which is significantly higher than 5.6% in the general population (p = 0.00001). The incidence of thrombosis in EIA + COVID-19 patients in the literature was 56.4% which is significantly higher than reported rates of thrombotic events in in all COVID-19 patients in the literature at 4.8%1 (p = 0.00001). Conclusion Our study indicates incidence of HIT is higher in the COVID-19 population. This can be attributed to the cytokine storm and severe sepsis seen in critically ill COVID-19 patients. Our study also suggests that development of HIT can contribute to increased risk for thromboembolic events as well as mortality of COVID-19 patients, however, our study is limited due to small sample size.

Background Accurate diagnostic biomarker testing is crucial to treatment decisions in breast cancer. Biomarker testing is performed on core needle biopsies (CNB) and is often repeated in the surgical specimen (SS) after resection. As differences between CNB and SS testing may alter treatment decisions, we evaluated concordance between CNB and SS as well as associated changes in treatment and clinical outcomes. Methods We performed a retrospective analysis of breast cancer patients at our institution between January 2010 and May 2020. Concordance between CNB and SS was assessed for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Survival in patients, including recurrence, metastatic recurrence, and death, were assessed using chi‐squared likelihood ratio. Results In total, 961 patients met eligibility criteria. Concordance, minor discordance, total concordance (concordance plus minor discordance), and major discordance between CNB and SS were reported for ER (87.7%, 9.2%, 90.8%, and 2.9%), PR (58.1%, 29.1%, 87.2%, and 12.8%), and HER2 IHC (52.5%, 20.9%, 73.4%, 26.6%), respectively. HER2 FISH concordance and major discordance were 58.5% and 1.2%, respectively. Of major discordance, ER (48.2%, p < 0.001) and HER2 FISH (50.0%) led to more management changes than HER2 IHC (2.4%, p = 0.04) and PR (1.6%, p = 0.10). Patients with ER major discordance had increased risk of death (6.7% concordance vs. 22.2% major discordance, p = 0.004). Conclusion Overall, retesting ER and HER2 was more clinically beneficial than retesting PR. To aid decision‐making and minimize healthcare costs, we propose patient‐centered guidelines on retesting biomarker profiles.

Patients with HER2-positive breast cancer have seen improved survival and outcomes over the past two decades. As patients live longer, the incidence of CNS metastases has increased in this population. The authors’ review outlines the most current data in HER2-positive brain and leptomeningeal metastases and discuss the current treatment paradigm in this disease. Up to 55% of HER2-positive breast cancer patients go on to experience CNS metastases. They may present with a variety of focal neurologic symptoms, such as speech changes or weakness, and may also have more diffuse symptoms related to high intracranial pressure, such as headaches, nausea, or vomiting. Treatment can include focal treatments, such as surgical resection or radiation (focal or whole-brain radiation), as well as systemic therapy options or even intrathecal therapy in the case of leptomeningeal disease. There have been multiple advancements in systemic therapy for these patients over the past few years, including the availability of tucatinib and trastuzumab-deruxtecan. Hope remains high as clinical trials for CNS metastases receive greater attention and as other HER2-directed methods are being studied in clinical trials with the goal of better outcomes for these patients.

e12518 Background: Oncotype dx is a 21 gene breast cancer assay that helps predict benefit of chemotherapy in early-stage hormone receptor positive (HR+), HER2 negative, 0 to 3 node positive breast cancer as reported by TAILORx and RxPonder trials. Both trials found no benefit of adjuvant therapy in mid-range scores of 11-25 with the exception of some benefit in age under 50 or premenopausal status, no benefit if score was 0-10, and benefit of chemotherapy if >25. Methods: All breast cancer patients between 2019-2020 were chart checked to evaluate oncotype dx scores. Patient characteristics were analyzed between oncotype dx scores of 0-10, 11-25, and >25 using X square tests. 2000-2020 institutional cancer registry data was analyzed to understand recurrence and mortality in patients with oncotype dx testing. Results: 173 patients had oncotype dx testing between 2019-2020, and most were HR+, HER2-, and had 0-3 lymph nodes. There was no difference in race or ethnicity between the groups of oncotype dx scores (Table), and average age at diagnosis for all three groups was 58 years. More patients with lower oncotype dx score had hormone therapy, but this was not significant (0-10 at 93.6%, 11-25 at 90.8%, and >25 at 82.1%, p=0.26). Patients with a higher oncotype score were significantly more likely to have chemotherapy (0-10 at 0%, 11-25 at 17.3%, and >25 at 82.1%, p<0.01). When looking at long term outcomes, the mortality rate was highest in the 11-25 score group at 9.5%, but was not significantly higher than 0-10 at 4.7% and >25 at 2.1% (p=0.15). The recurrence was highest in the 0-10 group at 5.4%, but not significant compared to the 11-25 group at 4.1% and >25 group at 4.2% (p=0.09). Conclusions: Race, ethnicity, and age does not impact predisposition to high oncotype dx score, which is interesting since literature shows minority women have higher mortality rates. This could be because oncotype dx looks at early-stage breast cancers and many minority women have later stages at diagnosis. There was no difference in which group received hormone therapy and there was significantly higher rate of chemotherapy administration in patients with scores >25, which is consistent with prospective trial recommendations. When evaluating long term outcomes between oncotype dx groups over 20 years, there was no significant difference in recurrence of disease or mortality indicating that oncotype dx scoring accurately predicted overall benefit of chemotherapy.[Table: see text]