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Background Altered tumor suppressor genes (TSG-alt) in prostate cancer are associated with worse outcomes. The prognostic value of TSG-alt in metastatic, hormone-sensitive prostate cancer (M1-HSPC) is unknown. We evaluated the effects of TSG-alt on outcomes in M1-HSPC and their prognostic impact by first-line treatment. Methods We retrospectively identified patients with M1-HSPC at our institution treated with first-line androgen deprivation therapy plus docetaxel (ADT + D) or abiraterone acetate (ADT + A). TSG-alt was defined as any alteration in one or more TSG. The main outcomes were Kaplan–Meier-estimated progression-free survival (PFS) and overall survival, analyzed with the log-rank test. Clinical characteristics were compared with the χ2 test and Kruskal–Wallis rank sum test. Cox regression was used for univariate and multivariable analyses. Results We identified 97 patients with M1-HSPC: 48 (49%) with ADT + A and 49 (51%) with ADT + D. Of 96 patients with data available, 33 (34%) had 1 TSG-alt, 16 (17%) had 2 TSG-alt, and 2 (2%) had 3 TSG-alt. The most common alterations were in TP53 (36%) and PTEN (31%); 6% had RB1 alterations. Median PFS was 13.1 (95% CI, 10.3–26.0) months for patients with normal TSGs (TSG-normal) vs. 7.8 (95% CI, 5.8–10.5) months for TSG-alt (P = 0.005). Median PFS was lower for patients with TSG-alt vs TSG-normal for those with ADT + A (TSG-alt: 8.0 [95% CI, 5.8–13.8] months vs. TSG-normal: 23.2 [95% CI, 13.1–not estimated] months), but not with ADT + D (TSG-alt: 7.8 [95% CI, 5.7–12.9] months vs. TSG-normal: 9.5 [95% CI, 4.8–24.7] months). On multivariable analysis, only TSG-alt predicted worse PFS (hazard ratio, 2.37; 95% CI, 1.42–3.96; P Conclusions The presence of TSG-alt outperforms clinical criteria for predicting early progression during first-line treatment of M1-HSPC. ADT + A was less effective in patients with than without TSG-alt. Confirmation of these findings may establish the need for inclusion of molecular stratification in treatment algorithms.

Objective In this study, we aimed to determine the cause of death (COD) after the diagnosis of neuroendocrine tumors (NET). Methods We used the Surveillance, Epidemiology and End Results (SEER) Program to review patients diagnosed with NET during 2000 to 2016. Patients were followed until death, and different CODs were determined. Results Of 94,399 patients with NETs, 40.9% died during the study period. During the first year of diagnosis, most deaths were from NETs (73%), followed by other cancers (11.2%) and cardiac diseases (4.6%). After more than 10 years, NET deaths decreased to 24.3%, whereas other cancers and cardiac disease became more common. Neuroendocrine tumors were responsible for 42.8%, 63.4%, and 81.2% of deaths in grade I, grade II, and grade III, respectively. For grade I localized NET, other cancers (22.2%) were the most common COD followed by NET (19.7%), whereas in grade 2 localized NET, NET was COD in 31.1% of cases followed by other cancers (22.4%). In metastatic disease, NET was the most common COD regardless of grade. Conclusions For low-grade localized NET, deaths were mostly secondary to non-NET causes. In contrast, NET is responsible for most of deaths in metastatic NET regardless of grade.

Background Genomic biomarkers that predict response to anti‐PD1 therapy in prostate cancer are needed. Frameshift mutations are predicted to generate more neoantigens than missense mutations; therefore, we hypothesized that the number or proportion of tumor frameshift mutations would correlate with response to anti‐PD1 therapy in prostate cancer. Methods To enrich for response to anti‐PD1 therapy, we assembled a multicenter cohort of 65 men with mismatch repair‐deficient (dMMR) prostate cancer. Patient characteristics and outcomes were determined by retrospective chart review. Clinical somatic DNA sequencing was used to determine tumor mutational burden (TMB), frameshift mutation burden, and frameshift mutation proportion (FSP), which were correlated to outcomes on anti‐PD1 treatment. We subsequently used data from a clinical trial of pembrolizumab in patients with nonprostatic dMMR cancers of various histologies as a biomarker validation cohort. Results Nineteen of 65 patients with dMMR metastatic castration‐resistant prostate cancer were treated with anti‐PD1 therapy. The PSA50 response rate was 65%, and the median progression‐free survival (PFS) was 24 (95% confidence interval 16–54) weeks. Tumor FSP, more than overall TMB, correlated most strongly with prolonged PFS and overall survival (OS) on anti‐PD1 treatment and with density of CD8+ tumor‐infiltrating lymphocytes. High FSP similarly identified patients with longer PFS as well as OS on anti‐PD1 therapy in a validation cohort. Conclusion Tumor FSP correlated with prolonged efficacy of anti‐PD1 treatment among patients with dMMR cancers and may represent a new biomarker of immune checkpoint inhibitor sensitivity. Implications for Practice Given the modest efficacy of immune checkpoint inhibition (ICI) in unselected patients with advanced prostate cancer, biomarkers of ICI sensitivity are needed. To facilitate biomarker discovery, a cohort of patients with DNA mismatch repair‐deficient (dMMR) prostate cancer was assembled, as these patients are enriched for responses to ICI. A high response rate to anti‐PD1 therapy in these patients was observed; however, these responses were not durable in most patients. Notably, tumor frameshift mutation proportion (FSP) was identified as a novel biomarker that was associated with prolonged response to anti‐PD1 therapy in this cohort. This finding was validated in a separate cohort of patients with nonprostatic dMMR cancers of various primary histologies. This works suggests that FSP predicts response to anti‐PD1 therapy in dMMR cancers, which should be validated prospectively in larger independent cohorts., Biomarkers of immune checkpoint inhibition sensitivity are needed. This article reports on genomic biomarkers that may predict response to anti‐PD1 therapy in prostate cancer.

Key Points Question Do patients receiving abiraterone acetate with prednisone as first-line therapy for the treatment of metastatic castration-resistant prostate cancer with bone metastases benefit from the addition of bone resorption inhibitors? Findings In this cohort study of 745 patients receiving first-line abiraterone acetate with prednisone for the treatment of metastatic castration-resistant prostate cancer with bone metastases, the use of concomitant bone resorption inhibitors was associated with improvements in overall survival, particularly among those with a high volume of disease. Meaning These findings suggest that the addition of bone resorption inhibitors to abiraterone acetate with prednisone as first-line therapy could be beneficial for the treatment of patients with metastatic castration-resistant prostate cancer with bone metastases., Importance Bone resorption inhibitors (BRIs) are recommended by international guidelines to prevent skeletal-related events (SREs) among patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. Abiraterone acetate with prednisone is currently the most common first-line therapy for the treatment of patients with mCRPC; however, the clinical impact of the addition of BRIs to abiraterone acetate with prednisone in this disease setting is unknown. Objective To evaluate the association of the use of concomitant BRIs with overall survival (OS) and time to first SRE among patients with mCRPC and bone metastases receiving abiraterone acetate with prednisone as first-line therapy. Design, Setting, and Participants This retrospective cohort study collected data from 745 consecutive patients who began receiving abiraterone acetate with prednisone as first-line therapy for mCRPC with bone metastases between January 1, 2013, and December 31, 2016. Data were collected from 8 hospitals in Canada, Europe, and the US from June 15 to September 15, 2019. Exposures Patients were classified by receipt vs nonreceipt of concomitant BRIs and subclassified by volume of disease (high volume or low volume, using definitions from the Chemohormonal Therapy Vs Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer [CHAARTED] E3805 study) at the initiation of abiraterone acetate with prednisone therapy. Main Outcomes and Measures The primary end point was OS. The secondary end point was time to first SRE. The Kaplan-Meier method and Cox proportional hazards models were used. Results Of the 745 men (median age, 77.6 years [interquartile range, 68.1-83.6 years]; 699 White individuals [93.8%]) included in the analysis, 529 men (71.0%) received abiraterone acetate with prednisone alone (abiraterone acetate cohort), and 216 men (29.0%) received abiraterone acetate with prednisone plus BRIs (BRI cohort). A total of 420 men (56.4%) had high-volume disease, and 276 men (37.0%) had low-volume disease. The median follow-up was 23.5 months (95% CI, 19.8-24.9 months). Patients in the BRI cohort experienced significantly longer OS compared with those in the abiraterone acetate cohort (31.8 vs 23.0 months; hazard ratio [HR], 0.65; 95% CI, 0.54-0.79; P, This cohort study examines whether the addition of bone resorption inhibitors is associated with improvements in overall survival and skeletal-related events among patients with metastatic castration-resistant prostate cancer receiving abiraterone acetate with prednisone as first-line therapy.

Background Early phase clinical trials evaluate the safety and efficacy of new treatments. The exclusion/inclusion criteria in these trials are usually rigorous and may exclude many patients seen in clinical practice. Our objective was to study the comorbidities limiting the participation of patients with breast, colorectal, or lung cancer in clinical trials. Materials and Methods We queried ClinicalTrials.gov on December 31, 2016. We reviewed the eligibility criteria of 1,103 trials. Logistic regression analyses were completed, and exclusion was studied as a binary variable. Results Out of 1,103 trials, 70 trials (6%) excluded patients >75 years of age, and 45% made no reference to age. Eighty-six percent of trials placed restrictions on patients with history of prior malignancies. Regarding central nervous system (CNS) metastasis, 416 trials (38%) excluded all patients with CNS metastasis, and 373 (34%) only allowed asymptomatic CNS metastasis. Regarding chronic viral infections, 347 trials (31%) excluded all patients with human immunodeficiency virus, and 228 trials (21%) excluded all patients with hepatitis B or C infection. On univariate analysis, chemotherapy trials were more likely to exclude patients with CNS metastasis and history of other malignancies than targeted therapy trials. Multivariate analysis demonstrated that industry-sponsored trials had higher odds of excluding patients with compromised liver function. Conclusion Many clinical trials excluded large segments of the population of patients with cancer. Frequent exclusion criteria included patients with CNS metastasis, history of prior malignancies, and chronic viral infections. The criteria for participation in some clinical trials may be overly restrictive and limit enrollment. Implications for Practice The results of this study revealed that most early phase clinic trials contain strict exclusion criteria, potentially excluding the patients who may be more likely to represent the population treated in clinical settings, leaving patients susceptible to unintended harm from inappropriate generalization of trial results. Careful liberalization of the inclusion/exclusion criteria in clinical trials will allow investigators to understand the benefits and drawbacks of the experimental drug for a broader population, and possibly improve recruitment of patients with cancer into clinical trials.

Importance While there have been multiple assessments of clinical trials leading to anticancer drug approvals by the US Food and Drug Administration (FDA), the cumulative percentage of approvals based on trials with a limitation remains uncertain. Objective To assess the percentage of clinical trials with limitations in 4 domains—lack of randomization, lack of significant overall survival advantage, inappropriate use of crossover, and use of suboptimal control arms—that led to FDA approvals from June 30, 2014, to July 31, 2019. Design, Setting, and Participants This observational analysis included all anticancer drug indications approved by the FDA from June 30, 2014, through July 31, 2019. All indications were investigated, and each clinical trial was evaluated for design, enrollment period, primary end points, and presence of a limitation in the domains of interest. The standard-of-care therapy was determined by evaluating the literature and published guidelines 1 year prior to the start of clinical trial enrollment. Crossover was examined and evaluated for optimal use. The percentage of approvals based on clinical trials with any or all limitations of interest was then calculated. Main Outcomes and Measures Estimated percentage of clinical trials with limitations of interest that led to an anticancer drug marketing authorization by the FDA. Results A total of 187 trials leading to 176 approvals for 75 distinct novel anticancer drugs by the FDA were evaluated. Sixty-four (34%) were single-arm clinical trials, and 123 (63%) were randomized clinical trials. A total of 125 (67%) had at least 1 limitation in the domains of interest; 60 of the 125 trials (48%) were randomized clinical trials. Of all 123 randomized clinical trials, 37 (30%) lacked overall survival benefit, 31 (25%) had a suboptimal control, and 17 (14%) used crossover inappropriately. Conclusions and Relevance Two-thirds of cancer drugs are approved based on clinical trials with limitations in at least 1 of 4 essential domains. Efforts to minimize these limitations at the time of clinical trial design are essential to ensure that new anticancer drugs truly improve patient outcomes over current standards.

Recent clinical trials have addressed the notion of early treatment of smoldering multiple myeloma (SMM). The results evidence improvement in progression-free survival and, in one study, overall survival. Although the treatment of SMM can be considered under specific circumstances, we propose here that careful interpretation of the clinical trials and the patient-specific data are needed before recommending therapy. In particular, many questions remain regarding the best regimen to be used as well as how to adapt based on the underlying disease biology. Hematologists should have a very thorough understanding of models designed to predict the progression from SMM to multiple myeloma, because their correct interpretation is paramount to establish proper care. Although there is no doubt that treatment should be started before overt end-organ damage, we do not believe that the current data support the widespread treatment of all SMM.

OBJECTIVE To determine the presence of racial/ethnic differences in patients with anemia and serum folate deficiency. METHODS We performed a retrospective analysis of data from patient samples collected from January 2010 to October 2018. Reference laboratory ranges were determined by Mayo Clinic Reference Laboratories. Race and ethnicity were classified according to National Institutes of Health categories. RESULTS The analysis comprised 197 974 samples. Hemoglobin, hematocrit, and SF results were available for 173 337, 173 056, and 129 760 samples, respectively. Of the samples, 46 505 (26.8%) showed anemia, with a higher prevalence among American Indian/Alaskan Natives (AI/AN) 42.9% and African Americans (AA) 47.2% (P

Introduction: Patients with coronavirus disease 2019 (COVID-19) have an increased risk for venous thromboembolic events. Thrombotic events contribute to the morbidity and mortality associated with COVID-19 infection, and have prompted investigation into strategies for mitigating thrombosis risk in patients hospitalized with COVID-19 infection. Our team reviewed the charts of patients hospitalized with COVID-19 pneumonia at a tertiary hospital in metropolitan Phoenix Arizona between 2020-2021, to assess frequency and efficacy of utilizing a VTE prophylaxis algorithm designed to prevent thrombosis in patients infected with COVID-19. Methods: A total of 846 patients were retrospectively evaluated to determine if they were treated with guideline-appropriate anticoagulation while hospitalized with COVID-19, as well as if they developed venous or arterial thrombotic events, or major or minor bleeds. 317 patients were excluded for taking therapeutic anticoagulation prior to admission, or for having a COVID-19 diagnosis >7 days after admission. Appropriate anticoagulation was determined by an institutionally designed COVID-19 thromboprophylaxis algorithm, based on platelet count, d-dimer, bleeding risk, and level of medical care required. Regimen options included: no anticoagulation, prophylactic enoxaparin (40 mg SQ daily) or heparin in the setting of kidney dysfunction, weight-based dosing of enoxaparin (40 mg SQ BID if BMI>40), intermediate intensity enoxaparin without thrombus (30 mg BID if BMI40), and therapeutic anticoagulation (for example enoxaparin 1 mg/kg BID) with thrombus. Demographics: Demographic data and clinical characteristics were collected for 529 patients. Average age was 59 years old, and the majority were men (58.4%). Most patients were White (58.3%), followed by Hispanic (17.8%), or Native American (15.7%). Fewer patients had a normal BMI (21.3%; BMI 18.5 - 24.9) compared to those who were overweight (31.2%; BMI 25-29.9) or obese (43.1% BMI > 30). Other comorbidities included Type 1 or Type 2 diabetes mellitus (N= 172, 32.5%), hypertension (N = 271, 51.2%), and hyperlipidemia (N = 176, 33.3%). Results: A total of 42 patients (8%), were diagnosed with a venous thrombosis during hospitalization. Patients admitted to the ICU were significantly more likely to have a thrombotic event of any type compared to non-ICU patients (21.6% to 5.7%; p < 0.001). Specifically, critically ill patients had higher incidences of deep vein thrombosis (9.5% to 0.7%), pulmonary emboli (8.1% to 4.8%), and superficial thrombi (2.7% to 0.2%). Only 1.1% of patients (6/529) experienced any bleeding, of which 3 were classified as a major bleed. Discussion: Among patients hospitalized at our institution with COVID-19, the majority were anticoagulated appropriately according to the COVID-19 thromboprophylaxis algorithm. Overall incidence of thrombosis in the study population was 8%. A significantly higher percent of critically ill patients had thrombi, supporting reports of correlation between severity of illness and thrombosis risk. The two regimens of anticoagulation least adhered to were weight-based and intermediate-based dosing, likely reflecting a departure from the hospital's thromboprophylaxis regimens prior to COVID-19 pandemic. Further studies are needed to characterize whether identifiable risk factors correlate with the incidence of thrombosis, and whether treatment with lower than recommended doses of anticoagulation, based on the COVID-19 thromboprophylaxis algorithm, were associated with thrombosis. Disclosures No relevant conflicts of interest to declare.

Introduction: Response assessment at day 100 post Autologous Stem Cell Transplant (ASCT) is associated with long-term relapsed free survival (RFS) and overall survival (OS) in multiple myeloma (MM). The International Myeloma Working Group (IMWG) are the preferred criteria to define best response to treatment and define relapse. In the last years, response assessment has incorporated minimal residual disease (MRD) status -associated with improved RFS and OS (Munshi et al); and PET/CT combined with clinical characteristics -also associated with favorable outcomes (Zamagni et al. NCT01910987; MMY3033). The 2016 IMWG MRD criteria, combined imaging (PET/CT) plus next-generation sequencing (NGS) MRD-negative to define complete response (CR). To our knowledge, there is limited data examining the correlation and prognostic value of MRD and FDG-PET/CT at day 100 post ASCT in MM. IN this study, we aimed to determine the prognostic valued of MRD by NGS combined with PET/CT in RFS and OS status after high dose chemotherapy and ASCT in MM. Methods: Patients who underwent ASCT for MM at Mayo Clinic Arizona and had MRD and PET/CT data were included in the study. Clinical data was obtained via retrospective chart review. Cytogenetic risk (CyR) was classified using the mSMART criteria . Disease and ASCT related characteristics were compared by MRD status. MRD was measured by NGS on bone marrow aspirates using the previosly validated clonoSEQ ® Assay (Adaptive Biotechnologies Corporation, Seattle, USA) tracking the IgH, IgK and IgL rearrangements at a minimum sensitivity level of 10-5. MRD was defined by residual clonal cells per million nucleated cells as: negative= 0, borderline= 1-5, positive >5. PET/CT scans were performed locally at baseline and at day 100. Comparisons were performed using the chi-square test for categorical variables, Wilcoxon rank-sum test for continuos variables, McNemar's test and Cohens's Kappa for agreement measures. Results: A total of 103 patients had matched MRD and PET/CT assessment around day 100 (+/-9 days) and were included in the analysis. Median age at diagnosis was 62 years (range, 54-66 years), 71 patients (68.9%) were men. CyR was standard risk in 49 (47.6%), high-risk in 39 (37.9%) and unknown in 15 (14.6%) patients. Most 75 (72.8%) patients were MRD positive, 16 (15.5%) were MRD negative, and 12 (11.7%) borderline. The median main MRD clone detected was 64 (range 0-91,874). 70 patients (68%) and 33 (32%) had a negative and positive PET/CT respectively. The median follow-up time was 18 months (range, 13-31 months). At the time of data analysis, 10 patients (9.7%) had relapsed and only 4 (3.9%) had died. There was a high-correlation between MRD status and PET/CT, 31 patients (93.9%) with positive PET/CT were also MRD positive (p=0.0027). There were no statistical differences between PET/CT and CyR (p=0.95). We analyzed the correlation using the FREQ procedure (McNemars's test); there was a strong association between positive PET/CT and positive MRD in 31/33 patients (93.9%, high sensitivity), and low association for negative PET/CT the negative/borderline MRD in 26/70 (37.1%, low specificity; p Conclusions: In conclusion, we demonstrate that the combination of MRD by NGS (clonoSEQ ®) and PET/CT at day 100 are complementary and have a high sensitivity (true positive rate) and fair correlation of agreement but low specificity (true negative rate). PET/CT was the best most sensitive technique to prognosticate RFS and OS. We did not find prognostic correlation of MRD with RFS and OS. However, our findings might be confounded by the low risk of relapse and death, a longer follow-up may demonstrate clinically important differences. Our results add evidence that MRD plus PET/CT improve the definition of CR in MM patients post ASCT. Prospective studies are needed to elucidate the optimal timing and role of combined MRD, PET/CT with other prognostic markers of clinical outcomes. Disclosures Larsen: Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fonseca:Juno: Consultancy; Kite: Consultancy; Aduro: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Oncopeptides: Consultancy; GSK: Consultancy; AbbVie: Consultancy; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy; BMS: Consultancy; Celgene: Consultancy.

Introduction: Serum folate (SF), vitamin B12 (B12), and iron deficiency (def) are common causes of nutritional anemias (NA). These deficiencies are usually multifactorial, with nutritional and non-nutritional causes playing a role. SF, B12, and iron levels are usually ordered in the setting of anemia, and malnutrition with or without neurologic symptoms. Clinical evidence suggests that these def have a strong dietary component and socioeconomic status (SES). The relationship of NA and area-based SES in the US has not been studied. We aimed to determine the relationship of SES with the prevalence of NA. Methods: We performed a cross-sectional analysis of adult patients with SF, B12 and iron levels at Mayo Clinic Arizona and Florida between 2010 and 2018. Race was classified using the NIH criteria. Normal laboratory values were determined according to our lab reference and the US NHANES III. SF levels (mcg/Lt) were defined as deficient 400-900, and excess ≥900. Iron def was determined by ferritin levels (mcg/L) as low 336 for men, low 307 for women. Area-Level SES indicators: Median Household income (MHI), unemployment rate (UR), median gross rent month (MGRM), % uninsured, median house value (MHV), % high school; were geocoded by zip code using the 2014 American Community Survey. Demographics and clinical variables were compared between groups by chi-square test for frequency data or Kruskal Wallis rank-sum test for continuous variables. Results: 202,046 samples from 128,084 patients were analyzed. In the sample-level analysis, there were statistically significant associations between SES and SF def; all SES indicators except UR for B12 def; and no differences for iron def, except % uninsured (Table 1). There was no statistically significant interaction between race and SES for SF def and iron def. Race was a statistically significant modifier between B12 def and MHI (p Conclusions: We show significant relationships between SES and NA in the US. Differences were observed between SF def and all the SES indicators without race interactions. There were significant interactions between B12 def, race and SES for pts of White, Asian and Other race. There were no differences between SES and race for iron def. These relationships confirm that NA are related to area-level SES and other social determinants of health. Research regarding the causes of these disparities on a population level are needed. Disclosures No relevant conflicts of interest to declare.

e18518 Background: Initiatives enhancing equitable oncologic care are an increasingly emphasized priority. Our study aims to identify aspects of breast cancer (BC) care in which differences exist based on insurance coverage status. Methods: We performed a retrospective, case control study consisting of 39 Hispanic ethnicity uninsured patients (UP) with newly diagnosed BC at federally qualified health centers and 119 insured patients (IP) diagnosed at Mayo Clinic Arizona (MCA). Patients were matched 3:1 for age, stage, year of diagnosis, ER and HER2 status. Demographic information, clinical variables, and zip code level specific socioeconomic information were compared. Continuous variables were compared by Wilcoxon rank-sum test and categorical variables by chi-square test. All patients ultimately received their cancer treatment at MCA. Results: Similar treatment patterns with chemotherapy, surgery, and radiation treatment were observed between groups. Primary language was Spanish for 94% of UP and English for 97.5% of IP. The majority of UP were of Hispanic ethnicity (97.4%); IP were 83.2% non-Hispanic White, 9.2% Hispanic, 3.4% African American. Zip code level information reflected more unemployment with a median of 10.6% versus 6.9% p ˂ 0.001, percent of high school or lower (53.0 % v 23.2 %, p ˂ 0.001), and lower income for UP (33733.5 v 64728.0 p values ˂ 0.001). UP BMI was significantly higher (30.6 V 24.7, p=0.005), with presence of more co-morbidities; diabetes (28.2% v 5.0%, p ˂ 0.001), hypertension (35.9 % v 20.2%, p= 0.046), dyslipidemia (28.2% v 12.6%, p = 0.023), metabolic syndrome (p 23.7% v 8.5, p= 0.013), and tobacco use (17.9% v 2.5%, p ˂ 0.001). IP had higher alcohol use (52.9% v 5.3%, p ˂ 0.001). Genetics consultation was performed for 62.2% IP versus 35.9% UP (p=0.004), lower acceptance of oncology nutrition consultation for UP (29.4% vs 7.4%, p= 0.024) Median time from abnormal mammogram to biopsy (25.5 days vs. 14 days, p=0.056), and interval from diagnosis to treatment (62 days vs. 39 days) (p=0.001) were less favorable for UP compared to IP. Conclusions: In comparing the status of UP (primarily Hispanic, Spanish-speaking) and IP (primarily non-Hispanic White, English-speaking) with newly diagnosed BC we identified greater prevalence of co-morbidities and adverse social determinants of health in the former group. We identified access to genetic counseling services, access to oncology nutrition consultation, and timeliness of diagnostic biopsy and initiation of treatment as disparate features in the care pathway. These observations can allow development of tailored interventions to achieve greater equity in delivery of BC care.

10503 Background: Gender bias can be reinforced through the use of gender-subordinating language and differences in the forms of address. We examined how professional titles were used during speakers’ introductions at the American Society of Clinical Oncology (ASCO) Annual Meeting. Methods: A retrospective observational study of video-archived speaker introductions at the 2017 and 2018 ASCO annual meetings was conducted. Data were extracted by mixed-gender coders. Professional address was defined as professional title followed by full name or last name. Multivariable logistic regressions were used to identify factors associated with the form of address. Results: 2511 videos were reviewed and 812 met inclusion criteria. Regarding speakers’ characteristics, 530 (65%) were non-Hispanic white (NHW), 743 (92%) held a MD or MD-PhD degree, and 484 (60%) were an associate or full professor. Female speakers were less likely to receive a professional address compared to male speakers (61% vs. 81%, p < 0.001). Female speakers were more likely to be introduced by first name only (17% vs. 3%, p < 0.001). Males were less likely to use a professional address when introducing female speakers compared to male speakers (53% vs. 80%, p < 0.01). No gender differences in professional address were observed for female introducers (p = 0.13). Male introducers were more likely to address female speakers by first name only compared to female introducers (24% vs. 7%, p < 0.01). In a multivariable regression including gender, race, degree, and academic rank, male speakers were more likely to receive a professional address compared to female speakers (OR: 2.67, 95%CI: 1.81-3.94, p < 0.01). Black speakers of both genders were less likely to receive a professional address compared to NHW (OR: 0.10, 95%CI: 0.01-0.53, p < 0.01). Female gender was a predictor for a non-professional form of address (first name only) (OR: 9.50, 95%CI: 4.38-20.62, p < 0.01). Conclusions: When introduced by men, female speakers were less likely to receive a professional address and more likely to be introduced by first name only compared to male speakers. Selective use of forms of address may strengthen gender bias; more research is needed to explore the causes of this disparity and its influence.

Introduction: Bruton tyrosine kinase (BTK) inhibitors are a class of drugs that inhibit B-cell receptor (BCR) and are increasingly used in B-cell lymphoproliferative neoplasms, including chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and Waldenstrom's macroglobulinemia. Ibrutinib, a first-generation BTK inhibitor has been associated with increased risk of cardiovascular adverse events (AEs), including atrial fibrillation (AF), hypertension (HTN) and bleeding. These unique AEs are thought to be due to off-target effects. Acalabrutinib, a second-generation BTK inhibitor is characterized by less off-target effects, and is thought to be associated with a decreased risk of cardiovascular and other AEs. However, a head to head comparison of ibrutinib and acalabrutinib has not been conducted. Herein, we conducted a systematic review and network meta-analysis of AEs from prospective clinical trials of ibrutinib and acalabrutinib in B-cell lymphoproliferative disorders to compare their safety profile. Methods: We searched PubMed, Embase, Scopus, and Web of Science from database inception through November 15th 2019. Only full-text articles were included. Other inclusion criteria included prospective trials (single arm or randomized) with ibrutinib, ibrutinib plus anti-CD20 antibody, or acalabrutinib as investigational agents. Trials investigating BTK inhibitor plus chemotherapy were excluded. When updated results of prospective trials were available, data were extracted from the most recent publication with the longest follow-up. Reports of 17 AEs of interest, including number of events (any grade and grade 3 or higher) were documented. Rate of discontinuation was investigated. Results: Twenty-seven prospective clinical trials, 12 multicenter single-arm, 9 multicenter randomized, 5 single center single-arm, and 1 single center randomized, were included. Data from 29 study arms including 3207 patients were analyzed in 3 groups - ibrutinib, ibrutinib plus anti-CD20 antibody, and acalabrutinib with augmented Bayesian network meta-analysis and meta-regression implemented in R including packages gemtc and rjags. The most common any grade AEs (>20%) with ibrutinib were diarrhea (46%, 95% CI 36-55%), myalgias/arthralgias (37%, 95%CI 28-46%), fatigue (33%, 95% CI 24-42%), cough (26%, 95% 17-36%), anemia (23%, 95% 15-30%), thrombocytopenia (22%, 95% 15-30%), and pyrexia (21%, 95% 13-30%). The most common any grade AEs with acalabrutinib were headache (37%, 95%CI 26-48%), diarrhea (30%, 95% 20-41%), peripheral edema (21%, 95% 15-28%), fatigue (20%, 95% 11-29%), and myalgias/arthralgias (16%, 95% 8-24%). The most common any grade cardiovascular AEs with ibrutinib were bleeding/bruising (32%, 95% 23-41%), HTN (23%, 95% 15-32%), AF (9%, 95% 3-15%). The most common any grade cardiovascular AEs with acalabrutinib were bleeding/bruising (41%, 95% CI 30-52%), and HTN (6%, 95% 1-11%). The rate of AEs with ibrutinib compared to ibrutinib plus anti-CD20 antibody were similar so the data was pooled. Of all AEs of interest, there was a significant difference in any grade AEs favoring ibrutinib for headache (12% vs. 37%), and infections (35% vs 57%). There was a significant difference in any grade AEs favoring acalabrutinib for myalgias/arthralgias (16% vs. 37%), anemia (6% vs. 23%), thrombocytopenia (5% vs. 22%), and HTN (6% vs. 23%). After adjusting for median follow-up and age, there was no significant difference in rates of bleeding/bruising and any grade infections between ibrutinib and acalabrutinib. However, there was a significant difference favoring acalabrutinib for any grade HTN (OR 0.26, 95% CI 0.17-0.40) p Conclusions: Acalabrutinib appears to have an overall improved safety profile compared to ibrutinib. This is particularly true for anemia, thrombocytopenia, and cardiovascular AEs, including AF and HTN. Figure 1 Disclosures No relevant conflicts of interest to declare.

2057 Background: To date, a comprehensive evaluation of core limitations in clinical trials leading to anti-cancer drug approvals by the US Food and Drug Administration (FDA) has not been undertaken.The aim of this analysis was to assess the percentage of clinical trials with core limitations, defined as lack of randomization, lack of overall survival data, inappropriate use of crossover, and use of sub-optimal control arms that led to FDA approvals from 2014 to 2019. Methods: This observational analysis included all approved anti-cancer drug indications by the FDA from July 2014 through July 2019. All indications were investigated and each clinical trial evaluated for design, enrollment period, primary endpoints, and presence of core limitations. The standard of care therapy was determined by evaluating the literature and published guidelines 1-year prior to start of clinical trial enrollment. Crossover was examined and evaluated for optimal use. We then calculated the percentage of approvals based on clinical trials with any or all core limitations. Results: A total of 187 anti-cancer approvals were evaluated. The number of anti-cancer drug approvals doubled over time with 68 in first half of study period (June 2014 to December 2016) to 119 in second half of study period (January 2017 to July 2019). Of those, 125 (67%) were based on a clinical trial with at least one core limitation. 64 (34%) approvals were based on a single-arm clinical trial. Of the remaining 123 approvals based on randomized trials, 60 (32%) had a core limitation. Of all randomized trials, 37 (30%) lacked overall survival benefit, 31 (25%) had a sub-optimal control, and 17 (14%) used crossover inappropriately. Conclusions: The majority of cancer drugs are approved based on clinical trials with core limitations. Efforts to minimize core limitations at the time of clinical trial design are essential to ensure that new anti-cancer drugs being marketed truly improve patient outcomes over current standards.

e20518 Background: Gut microbiome dysbiosis is correlated with graft-versus-host disease (GVHD) in allogeneic stem cell transplant (allo-SCT) patients. In the allo-SCT population, antibiotics have been associated with increased risk for GVHD mortality and relapse due to loss of gut obligate anaerobes . It has been shown that antibiotics may negatively impact the efficacy of checkpoint inhibitors for patients with solid tumors. Based on these studies, we performed a retrospective analysis to determine if antibiotic treatment affects outcomes of multiple myeloma (MM) patients after autologous SCT (ASCT). Methods: This is a single institution retrospective study at Hackensack University Medical Center. A list of consecutive MM patients treated from 1/2012 to 12/2015 was obtained and an electronic medical record review of the first 217 who received ASCT was performed. Baseline characteristics, treatment history, transplant course and antibiotic treatment (including β-lactams, fluoroquinolones, macrolides, metronidazole, and vancomycin) were reviewed. Prophylactic antibiotics were excluded. Response was defined using the IMWG criteria. Median progression free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Log rank tests were used to compare the difference in survival between stratified groups. The LASSO cox regression analysis method was used for multivariate analyses of PFS and OS. Results: Of the 217 patients, 205 patients were available for analysis. Median age at ASCT was 61. β-lactams were associated with decreased median PFS (1.95 vs 4.77 years (yrs), p < 0.01) and decreased median OS (7.51 vs 13.45 yrs, p = 0.01). Multivariate analysis adjusting for lasso-selected age, gender, complete remission (CR) after ASCT, and ISS demonstrated independent progression risk associated with β-lactam use (HR = 2.00, 95% CI, 1.28–3.12, p < 0.01). β-lactams were associated with worse OS in multivariate analysis adjusting for lasso-selected age, gender, CR after ASCT and high risk cytogenetics (HR = 1.89, 95% CI, 1.07–3.40, p = 0.03). Conclusions: In this preliminary study, β-lactams predicted for decreased PFS and OS compared to patients who did not receive β-lactams in MM patients undergoing ASCT. The study was limited by its retrospective nature but demonstrates one of the first evaluations of antibiotic effect on the ASCT population in MM. Prospective studies evaluating the impact of antimicrobials on patient outcomes and the gut microbiome are ongoing.

30 Background: BM in patients (pts) with CRPC are associated with shorter overall survival (OS) and higher costs. BRI zoledronic acid and denosumab are frequently used to prevent skeletal-related events (SRE) in pts with CRPC and BM. AA is the most common 1st line therapy for men with metastatic CRPC. We aimed to assess the impact of BRI on OS and time to first SRE (ttSRE) of pts receiving 1st line treatment AA for CRPC with BM. Methods: A retrospective cohort of pts starting AA as 1st line therapy for CRPC with BM between 2013-2016 was identified through 8 hospitals’ IRB approved registries. Pts were classified by use of concomitant BRI and subgrouped by volume of disease (per E3805 definition) at AA start. Kaplan-Meier method and Cox models were used to assess OS and ttSRE with hazard ratio (HR) estimates (95% CI). Results: Of the 745 pts included (543 deaths), 529 (71.0%) had AA alone and 216 (29.0%) AA+BRI. Median follow-up was 23.5 months. Pts receiving concomitant BRI showed a significantly longer OS and a 35% reduced risk of death compared to AA alone (HR=0.65; 95% CI, 0.54-0.79; P5, PS 0 vs. ≥1, and PSA are independently associated with longer OS. Conclusions: The addition of BRI to 1st line AA for CRPC men with BM was associated with improved OS, particularly in HV, and worsened ttSRE, more evident in LV. These data suggest a potentially different impact of concomitant BRI on HV vs. LV, which could affect clinical decision making.[Table: see text]

Background: Serum folate (SF), vitamin B12 (B12), and iron deficiencies (def) are common causes of nutritional anemias. These deficiencies are usually multifactorial, with nutritional and non-nutritional factors playing a role. SF, B12, and iron levels are usually ordered in the setting of anemia, and malnutrition with or without neurologic symptoms. Since folic acid fortification, the prevalence of SF def in the United States (US) is Methods: We performed a retrospective analysis of patients with SF, B12 and iron levels at Mayo Clinic Arizona between 01/2010 and 10/2018. Race was classified according to the NIH criteria. Normal laboratory values were determined according to our lab reference and the US National Health and Nutrition Examination Survey (NHANES) III. SF levels (mcg/Lt) were defined as deficient 400-900, and excess ≥900. Iron def was determined by ferritin levels (mcg/L) as low Results: A total of 79,926 SF, 107,731 B12, and 39,827 ferritin samples from 67,683 patients were analyzed. Demographics and sample analysis are presented in Table 1. In the sample-level analysis, 23,008 (25%) had anemia with higher prevalence in the American Indian/Alaskan Native (AI/AN) 49% and African Americans (AA) 43% (p Conclusions: In our cohort, we show that despite the low prevalence of nutritional anemias in the US, racial disparities exist. Major differences were observed in the prevalence of anemia, SF def and iron def especially among AI/AN and AA. These differences may be linked to medical causes, nutritional practices and other social determinants of health. More research regarding the causes of these disparities and its clinical implications on a population level are needed. Targeted strategies to improve folate, B12 and iron intake in at higher risk populations could decrease adverse outcomes and decrease healthcare disparities caused by nutritional anemias. T able 1. Sample-level comparison by race Disclosures No relevant conflicts of interest to declare.

Multiple myeloma (MM) occurs in all races, but the incidence in non-Hispanic black patients (NHBs) is two to three times higher than in non-Hispanic white patients (NHWs). We determined the representation of minorities and elderly patients in MM clinical trials. Enrollment data from all therapeutic trials reported in ClinicalTrials.gov from 2000 to 2016 were analyzed. Enrollment fraction (EF) was defined as the number of trial enrollees divided by the 2014 MM prevalence. Participation in MM clinical trials varied significantly across racial and ethnic groups; NHWs were more likely to be enrolled in clinical trials (EF 0.18%) than NHBs (EF 0.06%, p

e14132 Background: The use of PD-1 inhibitors (PD1) has been limited due to the lack of prognostic markers of response. Previous studies have suggested that indirect inflammatory markers such as neutrophil lymphocyte ratio (NLR) and platelet lymphocyte ratio (PLR) may correlate with response to treatment and improved survival. We sought to evaluate the impact NLR and PLR in a real world cohort of patients (pts) with advanced solid tumors treated with PD1. Methods: Records of all pts treated with PD1 between 2011-2017 at the John Theurer Cancer Center were reviewed. NLR and PLR were registered at baseline and longitudinally. We dichotomized as low (lNLR/lPLR), and high (hNLR ≥5/hPLR ≥160). Univariate logistic regression and Cox proportional hazards were used for progression free survival (PFS), and overall survival (OS). Landmark analyses were performed at cycles 2 (C2), and 5 (C5). Results: 178 pts received 1131 cycles of PD1. Median age was 65 (range 24-93); 43% were female. ECOG was ≥1 for 85%. 142 pts (80%), and 89 (50%) received ≥2C and ≥5C respectively. In univariate analyses, baseline hNLR and hPLR were independently associated with inferior OS (median 7.8 vs 18.3 months; HR 1.77, 95% CI 1.21-2.43; p = 0.004), ) and (median 6.4 vs 15.6 months; HR 1.42, 95% CI 1.09-2; p = 0.04) respectively. On landmark analyses, lNLR and lPLR were associated with longer PFS and OS at 2C, and 5C. Longitudinally, lNLR and lPLR correlated with response rate; NLR decreased by 0.08 (95% CI: -0.19 to -0.04; p = 0.03) and PLR by 17 (95% CI: -29 to -14; p = 0.07) per month in responders compared with non-responders. hNLR or hPLR did not correlate with increase in autoimmune toxicities. Conclusions: hNLR, hPLR are adversely prognostic markers in pts receiving PD1 inhibitors in a “real world cohort”. These markers correlate with a longitudinal response and may help predict response. Further prospective studies are needed to determine their utility in decision making during treatment.

e16508 Background: BM in patients (pts) with CRPC correlate with higher mortality and costs. BRI zoledronic acid and denosumab are frequently used for the prevention of skeletal-related events (SRE) in pts with CRPC and BM. AA is the most common 1st line treatment for men with metastatic CRPC. We sought to evaluate the impact of BRI on time to first SRE (ttSRE) and OS of pts receiving 1st line therapy AA for CRPC with BM. Methods: We identified a cohort of men starting AA as 1st line therapy for CRPC with BM between 2013-2015 from 7 hospitals’ IRB approved registries. Pts were grouped by use of concomitant BRI and subgrouped by volume of disease (per E3805 definition) at AA start. The endpoints were OS, defined as time from AA start to death or last follow-up visit, and ttSRE. Results: Of the 338 pts included, 256 (76%) received AA alone and 82 (24%) AA+BRI. ECOG PS (PS) was ≥1 for 178 pts (52.7%). No statistically significant difference in ttSRE was found between the 2 cohorts [see Table]. Median follow-up for OS was 25.6 months. Pts receiving concomitant BRI showed a significantly longer OS and a 36% decreased risk of death compared to AA alone (HR = 0.64; 95% CI, 0.64 0.46-0.91; p = 0.012). Notably, OS in the AA alone group was shorter than commonly described. The OS benefit with BRI was greater for men with high volume disease (HV) (HR = 0.42; 95% CI, 0.25-0.71; p = 0.001). On MVA, BRI vs. no BRI, low volume of disease vs. HV, PS 0 vs. ≥1, baseline VAS pain ≤3 vs. > 5, and baseline PSA are independently associated with longer OS. Conclusions: Using a multicenter database, the addition of BRI to 1st line AA for CRPC men with BM and poor prognostic factors did not improve prevention of SRE. However, concomitant use of BRI and AA was associated with a significantly improved OS, particularly in HV. Further research to determine the driving factors is needed. [Table: see text]

Background One of the newest methicillin-resistant Staphylococcus aureus (MRSA) antibiotics to receive FDA approval is ceftaroline fosamil, a member of a new subclass of cephalosporins with unique activity against MRSA. However, ceftaroline is currently only FDA approved for complicated skin/soft tissue infections and community-acquired pneumonia; there are currently no clinical data regarding its use in MRSA bacteraemia and endocarditis. We report a series of six patients in which ceftaroline was utilized as salvage monotherapy in persistent MRSA bacteraemia or endocarditis. Methods Using pharmacy records, 11 ceftaroline-treated patients were identified between January 2011 and November 2011 at University Health System and the South Texas Veterans Health Care System in San Antonio, TX, USA. All cases were reviewed and six patients received ceftaroline therapy for MRSA bacteraemia or endocarditis due to persistent or recurrent bacteraemia while on standard antibiotics (vancomycin or daptomycin). Results All six patients experienced rapid clearance of their bacteraemia after starting ceftaroline. In the case of endocarditis for which the patient subsequently developed heart failure and required valve replacement, there was no evidence of growth from cultures taken from the excised valve, suggesting sterilization within 13 days of starting ceftaroline. Conclusions Ceftaroline exhibits potent anti-MRSA activity in both in vitro and animal studies, including rabbit endocarditis models; however, the lack of clinical data has limited its use in bacteraemia and endovascular infections in humans. We hope that this series serves as an initial stepping stone for further evaluation of this compound for more invasive infections due to MRSA.

Background: Multiple myeloma (MM) accounts for approximately 1% of all cancers and 10% of hematologic malignancies in the United States (U.S.). MM occurs in all races, but the incidence in African Americans is two to three times higher than in non-Hispanic whites. MM is also slightly more frequent in men than women (1.4:1). Many clinical trials lack appropriate representation of specific patient populations, limiting the generalizability of the evidence obtained. Therefore, we determined the representation of ethnic minorities, the elderly, and women in MM clinical trials. Methods: Enrollment data from all therapeutic trials reported as completed in clinicaltrial.gov from 2000 to 2016 were analyzed. Clinical trials including other hematologic malignancies and with recruitment outside of the U.S. were excluded. Enrollment fraction (EF) was defined as the number of enrollees divided by the 2013 SEER database MM complete prevalence. Chi-square test was used to estimate differences in categorical data. Results: Out of 177 MM clinical trials (CT), 78 (44%) reported ethnicity with a total of 12,055 enrollees. Regarding enrollees' ethnic composition, 84% were non-Hispanic White (NHW), 8.6% African American (AA), 2.8% Asian, 1.8% Hispanic, and 0.1% Native American/Alaskan Indian. Out of those 78 CT, 52 (66%) were phase II, 15 (19%) phase III, and 11 (14%) phase I. Most of the results were published from 2012 to 2016 (74%). Forty-six (59%) trials were sponsored by industry, 7 (9%) by NCI, and 25 (32%) were investigator initiated. Participation in CT varied significantly across ethnic groups, NHW were more likely to be enrolled in CT (EF of 0.23) than AA (EF of 0.08, p < 0.0001) and Hispanics (EF of 0.05, p< 0.0001). Males had a higher recruitment rate than females (58% vs. 42%), but this could be explained by the higher incidence of MM in males. Enrollees' median age was 62 years. Younger patients (< 65 years) were more likely to be enrolled in CT than the elderly (66% vs. 34%, p Conclusions: Despite the higher incidence of MM in African Americans and the elderly, the former only represented 8.6% of the study participants and 66% of these were less than 65 years of age; therefore, we are lacking data in the tolerability of these new agents in our aging MM population. We also observed that industry studies were less likely to recruit AA patients. Collaborations between investigators, sponsors, and the community are necessary to increase our minority and elderly patients' access to clinical trials. Citation Format: Narjust Duma, Miguel Gonzalez Velez, Jesus Vera-Aguilera, Richardo Parrondo, Veronica Mariotti, Jonas Paludo, Yucai Wang, Ronald Go, Alex Adjei. Diversity in multiple myeloma clinical trials [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A27.

e24026Background: Comprehensive genomic profiling to identify driver mutations for which effective therapies or clinical trials are available is part of the standard diagnostic evaluation for NSCLC...

Immunotherapy has been introduced into the treatment of numerous cancers with impressive survival benefits. However, several immune-related adverse events (irAEs) have been reported, including a spectrum of myocardial toxicities in 1-3% of patients, for which there is a need for increased awareness

Combination immunotherapy can have multiple immune-related adverse events (irAEs). Cardiac complications such as myocarditis and conduction abnormalities are exceptionally rare (

93 Background: Tumor mutational load (TML) has been proposed as a biomarker of responsiveness to novel immune checkpoint inhibitors (ICIs) due its association with increased neoantigen formation and tumor immunogenicity. Gastrointestinal cancers (GICs) are generally insensitive to ICIs; therefore the aim of this study was to evaluate the TML, clinically relevant genomic alterations (CRGAs), and PDL-1 status of GIC patients (pts). Methods: We analyzed samples of pts with GICs using a multiplatform profiling tool (Caris Life Sciences, Phoenix, AZ). TML and CRGAs were calculated based on next generation sequencing and mutational load was stratified as high (≥17 mut/Mb), intermediate (8-16 mut/Mb), and low (≤ 7 mut/Mb). PD-L1 status was determined by IHC. Descriptive statistics and simple linear regression were used for analysis. Results: A total of 85 pts with GICs were analyzed. The median pt age was 65. 53% were males and 47% were females. Tumors were colorectal 51%, pancreatic 13%, esophageal 13%, gastric 9%, hepatobiliary 11%, anal canal 4%, and small intestine 1%. 80 cases (94%) had an adequate sample for profiling and TML was available in 59 cases (74%). Cases were 5% TML-high, 56% TML-intermediate, and 39% TML-low. The median TML was 9 mut/Mb and median CRGAs was 3. The most commonly detected CRGAs were TP53 (56%), APC (44%), KRAS (40%), ATM (18%) and PTEN (6%). A positive but very weak correlation was found between TML and number of CRGAs (R2 = 0.3). PD-L1 status was available in 74 cases (93%) with 86% being PD-L1 negative and 14% PD-L1 positive. PD-L1 expression was most commonly seen in esophageal (50%) and anal canal (30%) cancers. Among 57 tumors tested for both biomarkers, no correlation was found between a high TML and PD-L1 expression. Conclusions: TML varies among GICs, and higher TML scores were not associated with PD-L1 expression, but there was a weak correlation between TML and the number of CRGAs. Further analysis by stratification of GIC type and prognostic analysis to assess the correlation between TMB and response to ICIs is warranted.

594 Background: Given the heterogeneity of gastrointestinal cancers (GICs), molecular profiling is becoming part of the standard of care for many solid tumors. The aim of this study was to evaluate the molecular profile of patients (pts) with GICs using a multiplatform profiling tool and to assess how the pattern of detected molecular alterations could guide clinical decision-making in these tumors. Methods: We retrospectively analyzed samples of 85 pts with GICs via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) in order to evaluate clinically relevant genomic alterations (CRGAs) and clinically relevant biomarker expression (CRBs) in GICs. Results: A total of 85 pts with GICs were analyzed. 45 (53 %) were males and 40 (47%) were females. Tumors were colorectal 43 (51%), pancreatic 11 (13%) esophageal 11 (13%) gastric 8 (9%), hepatobiliary 8 (11%), anal canal 3 (4%), and small intestine 1 (1%). 80 cases (94%) had adequate sample for profiling. CRGAs were identified in 71 cases (89%) with a median of 3 CRGAs in the cohort. The most commonly detected CRGAs were TP53 45 (56%), APC 35 (44%), KRAS 32 (40%), ATM 14 (18%) and PTEN 5 (6%). The median number of CRBs was 9 and high expression levels were seen of mismatch repair biomarkers (MLH1, MSH2, MSH6, PMS2) in 45 (56%), TOPO1 in 44 (55%), PTEN in 27 (34%), TOP2A in 20 (25%), ERCC1 in 19 (24%), and both TS and TUBB3 in 17 (21%). Based on actionable CRGAs and CRBs, 94% of pts matched at least one FDA approved treatment with proven clinical benefit, with a median of 4 available therapies per pt. In addition, there was a median of 189 chemotherapy and 64 targeted therapy clinical trial opportunities available for these pts given the molecular blueprint of their GICs. Conclusions: Multiplatform molecular profiling identified a high frequency of actionable CRGAs and CRBs in GIC pts. This approach has the potential to aid in clinical decision-making by providing a stratification of beneficial therapeutic alternatives individualized to the molecular framework of tumor. Larger prospective studies are warranted to further investigate the impact of profiling guided treatment decisions on patient outcomes.

8044 Background: Racial disparities of FISH abnormalities in multiple myeloma (MM) have been well described in whites (W) but partially described in minorities (M) (Paulus et al, ASH 2016, 4432). We aimed to explore racial-based differences of FISH abnormalities using the largest cohort of m to date. Methods: CD-138 selected FISH was done on 799 consecutive patients (pts). Pts without symptomatic MM, and biopsy >6 months after diagnosis were excluded. The abnormalities evaluated included standard and intermediate risk: IGH rearrangements (IGH r), t(4;14), t(11;14), and high risk: t(14;20), t(14;16), del13q, del 17p, 1q21. Chi-square was used for statistical analysis. Due to smaller numbers, all m (Hispanic (H), Black (B), Asian (A) and Other (O)) were included into the same group for statistical analysis. Results: 482 pts were eligible, 343 (71%) were W, 52 (10%) H, 50 (10%) B, 19 (3%) A, and 18 (3%) O. Median age was 65 years, 54% were male, and 26% ISS stage 3. There were no were no statistically significant differences in FISH abnormalities between the m (Table1). Overall W had more abnormalities in IGH r, t(4;14), t(11;14), t(14:20), 1q21 gain compared to M. Most notably W had more IGH r (39% vs 28%; p=0.019) and t(11;14) (20% vs 12%; p=0.024). There were no statistically significant differences between W and m in the high risk FISH abnormalities. Conclusions: We had significant differences in FISH compared to M. W had more IGH r and t(11;14) than M, and there was no difference in high risk FISH abnormalities between W and M. This study confirms the biological racial disparities that exist in minorities with MM. Further studies with more inclusion of minorities are needed to elucidate these disparities and its effects on risk stratification and outcomes. [Table: see text]

e13521 Background: The use of next-generation sequencing (NGS) in clinical practice has increased the treatment (tx) options for cancer patients (pts). The expansion of genomic libraries used by NGS databases has resulted in increased identification of targetable genomic alterations (GAs). The aim of this study was to identify the clinical implications of genomic library expansion in the detection of GAs in pts with brain cancer at a large academic institution. Methods: We retrospectively analyzed 71 consecutive pts with brain cancer at the John Theurer Cancer Center that had NGS performed between 02/2014 and 09/2016. GAs were identified using the FoundationOne assay (Foundation Medicine, Cambridge, MA). GAs, number (n) of available genomic-directed tx and n of clinical trials were reviewed. The NGS assay interrogated 236 genes and introns of 19 genes until 09/2014, and subsequently was expanded to include 315 genes and introns of 28 genes. We compared median survival, n of GAs found, n of available trials, and n of tx available in pts who received NGS until 09/2014 (G1, n = 33) with pts who received NGS after 9/2014 (G2, n = 38). Results: Median survival was 30 months (range 19.9-40.1), median age was 62 years (range 26-82), the median n of GAs/sample was 5 (range 1-11). There was a significant positive correlation between n of GAs/sample and n of available trials and tx (r = .5, p = .00 and r = .3, p = .00, respectively). There was a negative correlation between survival and n of GAs (r = -.3, p = .02). G1 harbored 142 GAs with a median n of 4 GAs/sample (range 1-10), while G2 harbored 170 GAs with a median n of 5.5 GAs/sample (range 0-11). There was an absolute increase of 19.7% in GAs in G2 compared to G1. There was no difference in median overall survival. Conclusions: The expansion of genomic libraries increased the detection of GAs, and was positively correlated with the n of tx and clinical trials available for brain cancer pts. Survival was not affected by the expansion of the genomic library, but higher n of GAs was correlated with shorter survival. Expansions of NGS databases lead to increased n of potential tx options for brain cancer pts. Further studies are needed to investigate the impact of NGS targeted tx on survival.

e15722 Background: Pancreatic cancer (PaCa) is a highly lethal disease, with a 5-year overall survival (OS) rate of approximately 6%, and a median OS of only 3–6 months (m). Despite recent improvements in surgical techniques and increased use of combination chemotherapy (CT), OS remains poor. This study aims to examine the factors that led to increased OS in PaCa patients (pts) over the past two decades in a single academic institution. Methods: All medical records of pts diagnosed with PaCa at the John Theurer Cancer Center from 1990 to 2012 were reviewed, and 916 PaCa pts were included in this analysis. We compared one group of pts diagnosed from 1990 to 2003 (G1, n = 482), with a group of pts diagnosed from 2004 to 2012 (G2, n = 434) in terms of OS, demographics, tumor features and treatment (tx). Results: Median age at diagnosis was 70.5 years (range 26-96). There was no significant difference between G1 and G2 in terms of age at diagnosis, stage of disease and number of pts who received surgery. A significantly higher percentage of pts received CT in G2 compared to G1 (66.5% vs 51.0%, p = .00). Tumors of the pancreatic head were more common in G1 compared to G2 (51.8% vs 44.4% p = .02). More pts in G2 received two or more CT agents compared to G1 (49.0% vs 34.1%, p = .00). Median OS was significantly longer in G2 compared to G1 (9m vs 5m, p = .00), in pts who received CT compared to pts who did not (3m vs 9m, p = .00) and in pts who received surgery compared to pts who did not (5m vs 19m, p = .00). Pancreatic head location was associated with improved OS compared to other locations (9m vs 5m, p = .00). No OS difference was found between pts who received combination with two or more agents vs single agent CT. Conclusions: In line with multiple studies, analysis of PaCa data from our institution showed an increase OS in pts diagnosed with PaCa in more recent years, and in those who received surgery and CT. CT was administered in a larger number of pts in G2, which might account for the better OS in this group. Pts diagnosed with tumors of the pancreatic head had better survival, which could be explained by earlier presentation leading to earlier diagnosis and tx. Further research in PaCa therapeutics is needed, as long-term OS in PaCa pts remains poor despite recent advances.

e19525 Background: Rearrangements of the immunoglobulin heavy chain (IGH) on chromosome 14 are identified by FISH in about 15-20% of patients (pts) with newly diagnosed multiple myeloma (MM). Historically there is variation on the significance on prognosis of these rearrangements: typically, t(4;14), t(14;16) and t(14;20) have high risk (HR), and t(11;14) have standard risk (SR). A recent study (Kaufman et al, Leukemia. 2016 30:633-9) suggests that t(11;14) may confer a worse prognosis We report the prognostic significance of t(11;14) in a single-institution MM cohort. Methods: 87 pts with t(11;14) by CD 138 selected FISH at diagnosis were identified, pts without symptomatic MM were excluded. Cox regression was used for statistical analysis. Progression free survival (PFS), and overall survivals (OS) from diagnosis and post autologous stem cell transplant (ASCT) were analyzed by Kaplan-Meier. Results: Median age at diagnosis was 62 years, 45 pts (52%) were male, and 24 pts (27%) had ISS 3. All pts received either a proteasome inhibitor or an immunomodulatory agent, and 42 (48%) received triplet treatment as induction. Sixty-nine (79%) pts had ASCT, and overall response rate (ORR, partial response or better) post ASCT was 73%. For pts with HR FISH (defined as t(14;16), p53 del, 1q21 gain or 1p del) compared to SR FISH, the ORR post ASCT was 70% vs 77% (p = 0.67). OS from diagnosis was 93% at 3 years, 74% at 4 years and 51% at 5 years. Seven patients (8%) developed plasma cell leukemia, and there was no association between HR and SR FISH (p = 0.66). In multivariate analysis, ISS stage was an independent risk factor for mortality; pts with stage 3 had 7.3 times (CI: 1.16-36.4) and 5.7 times (CI: 1.63-20.0) the risk of mortality than pts with stage 1 and 2. Having an ASCT reduced mortality by 87% (CI: 0.04-0.41). Conclusions: Despite the use of novel therapies the OS at 5 years of our pts with MM was not significantly improved compared to SEER data from 1992-2013 (51% vs 48.5%). Pts with t(11;14) who had ASCT had increased survival compared to those who did not. Our results suggest that t(11;14) may confer a worse prognosis. Further prospective studies evaluating the risk of t(11;14) are warranted.

e12037 Background: Increased use of comprehensive genomic profiling (CGP) has recently led to improved genomic characterization of tumors, increased access to individualized therapies and increased availability of clinical trials in breast cancer patients. The aim of this study was to evaluate the clinical impact of genomic profiling in breast cancer patients with the use of a CGP assay at a large cancer center. Methods: We retrospectively analyzed 101 consecutive breast cancer patients who received CGP at the John Theurer Cancer Center between 12/2011 and 08/2016. Genomic alterations (GAs) were identified using the FoundationOne assay (Foundation Medicine, Cambridge, MA). GAs, number of available genomic-directed therapies and number of available clinical trials were reviewed. The CGP interrogated up to 315 genes and introns of 28 genes. Results: Median age at diagnosis was 58 years (range: 35-83 years). With a median follow-up of 189 months (range 1-189), median survival was 163 months (range 142-184). A total of 560 GAs were found in our population, with a median of 5.0 GAs/sample (range 0-16), a median of 2.0 therapies/patient (range 0-11), and a median of 11.0 clinical trials/patient (range 0-36). The most frequent GAs found were TP53 (47.5%, n = 48), PIK3CA (34.7%, n = 35), MYC (22.8%, n = 23), CCND1 (19.8%, n = 20), FGF3 (16.8%, n = 17), FGF4 (15.8%, n = 16), and ZNF703 (14.9%, n = 15). A significant positive correlation was found between number of GAs and the number of available targeted therapies and clinical trials (r = 0.5 and r = 0.7, p = 0.00, respectively). Increasing age is a predictor of having a PIK3CA mutation (OR = 1.05; CI:1.01-1.09, p = 0.00) while decreasing age is a predictor of having a MYC mutation by logistic regression (OR = 0.95; CI:0.91-0.95, p = 0.03). Conclusions: The systematic use of CGP led to the identification of a high number of GAs, which correlated with a median of 2.0 individualized therapies and a median of 11.0 clinical trials available for breast cancer patients. The clinical impact of genomic-directed individualized therapies needs to be further investigated in prospective, randomized studies.

803 Background: The routine use of comprehensive genomic profiling (CGP) has led to better genomic characterization, more personalized treatments and higher enrollment in clinical trials for many solid cancers. The aim of this study was to evaluate the clinical and genomic prolife of patients (pts) with gastrointestinal cancers (GIC) with the use of a CGP assay and their potential therapeutic benefit at a large comprehensive cancer center. Methods: We retrospectively analyzed 83 consecutive pts with GIC that had CGP at the JTCC between 01/2014-09/2016. Demographics, CGP results, and clinical characteristics were studied. Clinically relevant genomic alterations (CRGAs) were identified using the FoundationOne assay (Foundation Medicine, Cambridge, MA), and were defined as alterations linked to approved therapies and those under evaluation in genotype-driven clinical trials. Results: 83 pts with GIC were analyzed. 46.9% males and 53.0% females. The median age at diagnosis was 58.5 years. 73 (88%) patients were stage III/IV at diagnosis. Tumors consisted of colorectal (36%), gastric (24%), pancreatic (12%) and cholangiocarcinoma (6%). All the pts were found to have at least one genomic alteration (GA). CRGAs were identified in 63 (76%) of cases, with an average of 2 per pt. The most frequently identified GAs were TP53 43 (29.9%), APC 24 (16.7%), KRAS 31 (21.5%), ARID1A 12 (8.3%), PIK3CA 11 (7.6%), and SMAD4 11 (7.6%). Of the 63 pts with CRGAs, 23 (36%) received one of the therapies suggested by the NGS assay, and 9 (14%) were enrolled in a clinical trial. Conclusions: The use of CGP assay identified a high frequency of CRGAs in GIC pts. The assay provided information for genomic-directed therapy in 36% of the patients. The routine use of CGP in GIC may lead to pts receive more personalized treatments. The potential benefit of selected targeted therapies in individual cases suggests that larger studies of treatment guided by routine CGP in gastrointestinal malignancies are warranted.

774 Background: The use of next-generation sequencing (NGS) in clinical practice has increased the therapeutic options for many cancers. Multiple NGS assays are now commercially used. The genomic libraries used by these assays are continuously being expanded, resulting in increased detections of genomic alterations (GAs) leading to potential new treatments. The aim of this study was to identify the clinical and research implications of a database expansion in the detection of GAs in patients with gastrointestinal cancers (GIC). Methods: We retrospectively analyzed 83 consecutive patients with GIC that had NGS at the John Theurer Cancer Center between 01/2014 and 08/2016. GAs were identified using the FoundationOne assay (Foundation Medicine, Cambridge, MA). GAs, number of genomic-directed therapies and number of clinical trials were reviewed. Results: Period 1 (P1) comprised 01/2014-09/2014, period 2 (P2) comprised 10/2014-08/2016. The NGS assay interrogated 236 genes and introns of 19 genes during P1, and was expanded to 315 genes and introns of 28 genes during P2. The 21 samples analyzed during P1 harbored a total of 82 GAs with an average of 3.9 GAs/sample (range 1-7). The 62 samples analyzed during P2 harbored a total of 342 GAs with an average of 5.5 GAs/sample (range 1-20); representing an increase of 42% in GAs from P1 to P2. 41 GAs in 29 genes were detected in P2 that were not interrogated during P1. The average of genomic-directed therapies with potential clinical benefit increased from 1.8 during P1 vs 2.6 during P2 (44.4% increase in potential therapies). Based on new genomic findings, more clinical trials were made available during P2; an average of 8 vs 4 clinical trials (100% increase in available clinical trials). Conclusions: Periodical updates on NGS and the expansion of genomic libraries increase the detection of GAs, potential new genomic-directed therapies and available clinical trials. Continued expansions of NGS are needed to improve genomic characterization, and increase in the personalized therapeutic options for our patients with GIC.

791 Background: With the surge of drug development in the past decade, early phase clinical trials (EPCT) have gained value evaluating the potential benefits of new therapies. The inclusion/exclusion criteria in EPCT are usually rigorous and may exclude many patients (pts) commonly seen in clinical practice. Our objective was to identify the most common comorbidities excluded in EPCT for CRC. Methods: ClinicalTrials.gov was queried on December 1stof 2015. We reviewed the characteristics and eligibility criteria of 369 phase I/II interventional drug trials including: experimental arm therapy, location, and exclusion/inclusion criteria. Logistic regressions were completed and exclusion was studied as a binary variable. Results: Of the 369 trials, 68% were phase II and 32% phase I. 46% were conducted in the United States, 30% in Europe, 15% in Asia and 9% in other locations. 74 (20%) trials excluded pts > 70 years of age. 142 (39%) trials required creatinine levels < 1.5 mg/dl, liver enzymes (AST/ALT) < 2.5 and bilirubin < 1.5 of the upper limit of normal. Cytopenia was a significant exclusion factor: 147 (47%) trials required Hgb > 9 g/dl and 218 (59%) excluded pts with platelets < 100,000/dl. In terms of comorbidities, 98 (27%) trials excluded pts with heart failure (NYHA class 3/4), 74 (20%) with atrial fibrillation, 112 (31%) with any anticoagulation therapy and 155 (42%) with positive HIV. Trials located in the US were more likely to exclude pts with Hgb < 9g/dl (OR: 1.5, 95%CI: 1.1-2.3, p < 0.05), immunotherapy trials were more likely to exclude pts on any anticoagulation (OR:1.8, 95%CI: 1.2-2.8, p < 0.007) and targeted therapy trials were more likely to exclude pts with history of DVT/PE or cardiovascular diseases (OR: 3.4, 95%CI: 1.9-5.8, p < 0.0001; OR: 2.3, 95%CI: 1.3-3.8, p < 0.002, respectively). Conclusions: 20% of EPCTs on CRC excluded pts with advanced age, organ dysfunction and common comorbidities. Many of the EPCT reviewed were not inclusive of our aging oncology population who are more likely to have multiple comorbidities. Investigators should review whether sufficient justification exists for every exclusion criterion before their incorporation in future trial protocols.

e14053Background: CNS disease is common in multiple neoplasias, but clinical trials tend to exclude this patient population due to the increase in morbidity/mortality associated with CNS metastasis...

2529Background: Early phase clinical trials (EPCT) evaluate the potential benefits of new regimens and help guide the care of oncology patients (pts).The inclusion/exclusion criteria in EPCT are us...

Introduction: Autologous stem cell transplantation (ASCT) is the standard of care for treating patients with advanced lymphomas. The most commonly employed preparative regimens are BCNU (Carmustine), etoposide, cytosine arabinoside, melphalan (BEAM), and BCNU, etoposide, cyclophosphamide (CVP). Both regimens use BCNU, but this medication is associated with pulmonary toxicity, besides, in some underdeveloped countries there is a serious shortage of it. Carboplatin is an agent with good activity in Hodgkin and non-Hodgkin´s lymphomas and has a tolerable toxicity profile. Here we present our experience in a bone marrow transplant service in Colombia (South America) a country with shortage of BCNU. We evaluated the effects of a high-dose chemotherapy regimen with carboplatin replacing BCNU in the CVP regimen. Methods: After peripheral blood progenitor cells were mobilized with filgrastim 10 µg/kg for five days, twenty four patients with advanced lymphomas were conditioned prior to ASCT. The conditioning regimen consisted of carboplatin (450 mg/m2/ days -5,-4), etoposide (330 mgs mg/m2/days -4,-3,-2) and cyclophosphamide (2.000 mg/m2/days -3,-2,-1). After the autograft all patients received filgrastim or pegfilgrastim from day +5. Results: 24 consecutive patients were transplanted, median age 39.2 years (range 5-70), eleven were female. 11 patients (46%) had Hodgkin lymphoma; 7 in CR2 and four in partial remission or with refractory disease. 13 (54%) had non-Hodgkin´s lymphoma classified as: 6 diffuse large B cell, 5 mantle cell, 2 transformed follicular. Patients with mantle cell lymphoma were in CR1 while the rest were in CR2. The median CD 34+ cells infused was 4.09 x 106 cells/kg. The median time to achieve 500/µL absolute granulocyte count and 20.000/µL platelets was 11.7 days (range 8-17), and 16.5 days (range 7-23) respectively. 20 out of 24 had febrile neutropenia, the other toxicities were mild; grade II mucositis in three patients, neutropenic colitis in two and hemorrhagic cystitis in one. There were no pulmonary or renal toxicities and the transplant related mortality was 0%. The four patients with active disease achieved complete remission after transplant but two of them have relapsed. The one year overall survival is 100%, with a median follow-up of 12 months (range 5-18), and the disease-free survival, estimated by Kaplan-Meier is 90%. Conclusions: The use of carboplatin replacing BCNU in the CVP regimen seems to be a safe and effective conditioning protocol followed by ASCT in patients with various types of lymphomas. This treatment option seems an adequate alternative for underdeveloped countries with shortage of BCNU. The regimen shows good anti-tumor activity, with a tolerable toxicity profile. These promising results must be confirmed with the inclusion of more patients and a longer follow-up. Citation Format: Miguel Gonzalez Velez, Amado Jose Karduss-Urueta, Rosendo Perez, Luis Rodolfo Gomez, Juan Alejo Jimenez, Pedro Alejandro Reyes, Ana Cardona, Liliana Hurtado, Hilda Deossa, Clara Fernandez. Carboplatin replacing BCNU in the BCNU, etoposide, cyclophosphamide (CVP) regimen for autologous stem cell transplant in patients with advanced lymphoma. Very low toxicity and encouraging results. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C82.

534 Background: Surgical resection remains a mainstay of treatment for localized colorectal cancer (CRC). However, up to 35% of patients (pts) develop recurrence with a significant decrease in overall survival. The aim of this study was to evaluate clinical characteristics and specific predictors of recurrence for stage I/II CRC Methods: We performed a retrospective analysis of 2310 pts diagnosed with stage I/II CRC at our institution between 1990 and 2013, with a minimum follow up of 24 months. Tumor characteristics and recurrence data were studied. Cox regression was used for statistical analysis. Results: Of the 2310 pts, recurrence was identified in 276 (12%) pts, of which 88 (32%) pts had early recurrence ( < 1 year). Median time of recurrence was 625 days. 210 (76%) pts had local recurrence while 66 (24%) pts had distal recurrence, with liver being the main site of distant metastasis. Males had a higher recurrence rate than females (16% vs. 7%, p < 0.0001). When comparing recurrence pts (R) with non-recurrence (NR) pts, Hispanics were more prevalent in the R group (13% vs 8%, p < 0.01). R pts were more likely to have rectal and poorly differentiated tumors (33% vs. 13%, p < 0.0001; 23% vs. 14%, p < 0.0001, respectively). Mucinous adenocarcinomas were more prevalent in the R group (16% vs. 9%, p < 0.0005). In multivariate analysis: male sex (OR: 1.24, 95% CI: 1.21-1.56, p < 0.001), rectal tumors (OR: 4.2, 95% CI: 3.14-5.06, p < 0.001), tumor size (OR: 2.55, 95% CI: 1.31-4-51, p < 0.01), and positive margins (OR: 3.6, 95% CI: 2.13-5.21, p < 0.04) were independent predictors for recurrence. K-ras (+) status was a predictor of recurrence by univariate analysis. Age, race, and histologic grade were not predictors of recurrence. Pts with early recurrence had a lower median overall survival compared to pts that developed recurrence after 1 year, 37 months (95% CI: 26.6-49.6) vs. 59 months (95% CI: 42.4-74.3), p < 0.04. Conclusions: Pts with recurrence were more likely to have rectal and poorly differentiated tumors. Poorer survival was observed in pts with early recurrence. These findings could serve as important prognostic information and may help identify the pts that would benefit from aggressive surveillance after treatment.

11041 Background: Twitter (TW) is an essential tool in the medical community. Few studies have examined the use of TW by medical trainees. We aimed to assess its utilization among trainees in hematology-oncology related areas (HORAs). Methods: 576 training programs in HORAs were obtained. We contacted a potential pool of 3,142 trainees. A 50 item survey was distributed between 2/2019-5/2019, focusing on: demographics, professional use, attitudes toward TW, and patient interactions. Responses were analyzed using parametric descriptive statistics. Results: 442 responses (14% response rate) were received; 203 (46%) used a TW account for professional activities. See table for demographics. The most common reasons for using TW were: continuous education (73%), dissemination of information (62%), and networking (62%). > 80% of users have positive views on using TW for: promoting academic discussions (92%), trainees education (89%), and conference networking (83%). 50 (25%) have used TW for collaborations, with abstracts and papers being the most common (20%). Most agreed or strongly agreed that TW: is a useful education tool (89%), and might be useful for career advancement (85%). The most common challenges were: the value of TW content can be decreased by irrelevant content and biased sources (64%), not peer-reviewed (51%), and difficulty searching information (50%). 68% considered that programs should promote the engagement of trainees, but only 21% reported instruction in the use of TW. 83% agree or strongly agree that TW is useful for physicians and patient interactions, but 82% have concerns about legal repercussions. Conclusions: Almost half of trainees in HORAs use TW for professional activities. The most common uses are for education, dissemination of information and networking. Most trainees that use TW have positive views regarding education and academic collaborations. Use of Twitter may strengthen trainees’ education, provide mentorship opportunities, and promote career advancement. Challenges on TW use should continue to be addressed. [Table: see text]