Babiker, Hani M.

256 Background: PARP inhibitors, olaparib and rucaparib recently improved survival outcomes (in the Profound and Triton-2 trials) in pts with aPC harboring HRRm. Notably, ~35% of pts screened for the PROfound trial did not meet eligibility solely due to the lack of adequate quality/quantity of tumor tissue required for CGP (De Bono, NEJM, 2020). cfDNA analysis non-invasively assesses tumor-derived genomic alterations. We evaluated the prevalence of HRRm in a real-world aPC population, who had commercially available cfDNA assay results available. Methods: cfDNA based CGP (using a clinically-validated 73- to 74-gene panel i.e. Guardant360 or G360) from consecutive aPC pts between 11/2016–8/2020 were used for detection of HRRm. Frameshift and nonsense mutations were included as pathogenic. Variants of unknown significance were excluded. In this unmatched study, the prevalence of each HRRm was compared with those reported in literature using the chi square test. Results: cfDNA CGP from 7701 aPC pts were available for interrogation of BRCA1/BRCA2 mutations, & from 4671 aPC pts for ATM mutations. Prevalence of BRCA1 and 2 as detected by cfDNA was similar to historical CGP of primary tissue. Prevalence of BRCA1 was higher than historical CGP of metastatic tissue. Prevalence of ATM in cfDNA was higher than historic tumor tissue CGP but similar to prior reports from cfDNA testing (Table). Conclusions: In this large real-world population of pts with aPC undergoing routine cfDNA CGP by a CLIA certified lab, prevalence of HRRm was similar (or higher for BRCA1 and ATM) to what has been previously reported from the tumor tissue. These data provide the rationale for utilizing cfDNA CGP as a routine test for detection of HRRm in men with aPC to identify men who are candidates for PARPi. [Table: see text]

To report a multi-institutional case series of patients with advanced microsatellite instability high (MSI-H) prostate adenocarcinoma identified with clinical cell-free DNA (cfDNA) next-generation sequencing (NGS) testing and treated with immune checkpoint inhibitors. Retrospective analysis of patients with metastatic castration-resistant prostate cancer (mCRPC) and MSI-H tumor detected by a commercially available cfDNA NGS assay Guardant360 (G360, Guardant Health) at eight different Academic Institutions in the USA, from September 2018 to April 2020. From a total of 14 MSI-H metastatic prostate cancer patients at participating centers, nine patients with mCRPC with 56% bone, 33% nodal, 11% liver and 11% soft-tissue metastases and a median PSA of 29.3 ng/dL, were treated with pembrolizumab after 2 lines of therapy for CRPC. The estimated median time on pembrolizumab was 9.9 (95% CI 1.0 to 18.8) months. Four patients (44%) achieved PSA50 after a median of 4 (3–12) weeks after treatment initiation including three patients with >99% PSA decline. Among the patients evaluable for radiographic response (n=5), the response rate was 60% with one complete response and two partial responses. Best response was observed after a median of 3.3 (1.4–7.6) months. At time of cut-off, four patients were still on pembrolizumab while four patients discontinued therapy due to progressive disease and one due to COVID-19 infection. Half of the patients with PSA50 had both MSI-H and pathogenic alterations in BRCA1 and BRCA2 in their G360 assays. The use of liquid biopsy to identify metastatic prostate cancer patients with MSI-H is feasible in clinical practice and may overcome some of the obstacles associated with prostate cancer tumor tissue testing. The robust activity of pembrolizumab in selected patients supports the generalized testing for MSI-H.

e17539 Background: Chemotherapy with Docetaxel (D) or androgen pathway inhibition (API) with Abiraterone Acetate plus prednisone (AAP), Aplautamide(APA) and Enzalutamide(E) are acceptable, FDA approved treatment options for mCSPC. It is not clear whether the magnitude of benefit varies by the choice of initial agent [chemotherapy vs API] or by volume of disease [High vs Low]. Data is now available from all registration trials by volume status and motivated this analysis to inform initial treatment choice in mCSPC. Methods: We systematically searched MEDLINE(Ovid), Embase, and Scopus for randomized controlled trials of chemotherapy(D) or APIs (AAP, APA, ENZ) that had available hazard ratios (HRs) for overall survival (OS) and Progression Free Survival (PFS) according to patient’s volume of disease. We also reviewed abstracts and presentations from all major conference proceedings. We calculated the pooled overall survival HR and 95% CI by chemotherapy and APIs and by high volume(HVD) and low volume(LVD) using a random effect model, and tested for heterogeneity to assess the null hypothesis that no difference in the survival advantage exists by choice of initial agent and volume of disease. Results: Of 4456 studies identified in our search, there were 8 eligible randomized controlled trials that were included in the analysis. Both D and APIs significantly improved PFS [HR 0.48; 0.45-0.51] and OS [0.72; 0.64-0.81] when added to ADT, however the latter was associated with significantly higher improvement in PFS( P < 0.01) and OS (P = 0.03). In patients treated with D, patients with HVD derive significantly more benefit as compared to LVD( P = 0.046) and patients treated with APIs both HVD and LVD patients derive similar benefit( P = 0.80) (Table). Conclusions: mCSPC patients derive higher magnitude of survival benefit when treated with APIs as compared to D; however, D may be preferred in HVD patients. [Table: see text]

Background:Injectable azacitidine (AZA) has been evaluated in a variety of malignancies, including acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and solid tumors. CC‐486, the oral formulation of AZA, allows extended dosing schedules (>7 days per 28‐day treatment cycle) to increase AZA exposure to malignant cells over the course of the cycle. CC‐486 is under investigation in phase 3 clinical trials as maintenance therapy for patients with AML in first complete remission after induction chemotherapy (NCT01757535) and in lower‐risk MDS with concurrent thrombocytopenia and RBC transfusion dependence (NCT01566695). In these studies, patients receive CC‐486 300 mg QD administered in two 150 mg tablets. A single 300 mg CC‐486 tablet is in development for market approval.Aims:Evaluate the bioequivalence (BE) of a single 300 mg CC‐486 tablet relative to two 150 mg CC‐486 tablets, and the food effect (FE) on the bioavailability of the CC‐486 300 mg tablet.Methods:This was a phase 1, randomized, crossover study (NCT01519011). Adult patients had hematologic malignancies or solid tumors relapsed/refractory to prior therapy for which no standard treatments were available, and ECOG PS scores 0‐2. The BE phase assessed pharmacokinetic (PK) parameters of CC‐486 administered as two 150 mg tablets (formulation A) and as one 300 mg tablet (formulation B). Patients were randomized 1:1 to receive each formulation at least 48 hours apart. In the FE phase, patients were randomized to receive formulation B on each of 2 PK study days under fed (high fat, ∼800‐1000 calories) and fasted conditions. PK parameters, including area under the plasma concentration‐time curve from time 0 extrapolated to infinity (AUC∞), maximum plasma concentration (Cmax), time to Cmax (Tmax), terminal half‐life (t1/2), apparent total clearance (CL/F) and volume of distribution (Vz/F) were analyzed. BE of formulations A and B, and absence of FE on formulation B, were indicated when the 90% CI of the ratios of geometric means (RGM) based on log‐transformed data for AUC∞ and Cmax between formulations A and B, and between fed and fasted conditions, were within 80%>125%.Results:30 patients were enrolled in the BE phase (median age 68.5 yrs, range 46‐86); 3 patients (10%) had hematologic malignancies and 27 (90%) had solid tumors. Formulations A and B were bioequivalent: the Cmax RGM was 101.5% (90% CI 89.9, 114.7) and AUC∞ RGM was 105.7% (95.0, 117.6). Median Tmax was 1.0 hour for both formulations.57 patients enrolled in the FE phase (median age 62 yrs, 31‐88); all had solid tumors. Despite a lower Cmax under fed condition (RGM 78.9% [90%CI 68.6, 90.7]), overall drug exposure was similar (AUC∞ RGM 108.9% [90%CI 98.5, 120.5]) (Figure A). Consistent with an effect of gastric emptying, median Tmax was reached at 2 hrs and 1 hr post‐dose in fed and fasted states, respectively (Figure B) and mean t1/2 was 0.78 and 0.58 hr postdose. CL/F and Vz/F were comparable in fed and fasted states. Moderate to high intersubject variability was observed for all CC‐486 PK parameters (Figure A).Summary/Conclusion:A single oral CC‐486 300 mg tablet is bioequivalent to two 150 mg tablets. The PK profile for the CC‐486 300 mg tablet under fed and fasted conditions was comparable although Cmax occurred later and was decreased in fed vs. fasted condition. Systemic drug exposure (AUC∞) in fed and fasted states was similar and within the bioequivalence limits. Limited differences in other CC‐486 PK parameters between fed and fasted states are not expected to have a clinical impact.image

e13096 Background: Several studies have reported the association between atrial fibrillation (AF) and malignant cancer. Recently, results from a large cohort within the Women’s Health Study showed increased incident risk of breast, colon and lung cancer in patients with AF. Therefore, we performed a systematic review to assess the available evidence and a meta-analysis to define the strength of this association. Methods: MEDLINE, Cochrane and Scopus databases were searched for all prospective studies that reported the association between AF and presence of cancer. The HR for incident risk of common cancers was recorded (Breast, Lung, Colorectal) in patients with and without AF. Lung cancer was excluded because the data required for the analysis was not consistently reported. The DerSimonian-Laird random effects meta-analysis was performed to derive pooled Hazard Ratio (HR) estimates for incident risk of colorectal and breast cancer in patients with AF. Q-test was used to assess between-study heterogeneity; I2 statistic was computed to expresses the percentage of the total observed variability due to study heterogeneity. Results: A total of 390,479 participants in 3 prospective studies were included in the analysis. Mean age of participants was 66.3 ± 6.5 with mean follow up for 12.6 years. Patients with atrial fibrillation had 27% more risk of developing colorectal cancer [HR 1.27 (1.07-1.51) p < 0.005, I2= 73%] and 14% more risk of developing breast cancer [HR 1.14 (1.03-1.26) p = 0.01, I2= 37%] as compared to those without atrial fibrillation. Applying these hazard ratios to age adjusted yearly incidence ratios from 2000-2015, one in 5824 new onset AF cases will develop CRC and one in 7474 new onset AF cases will develop breast cancer. Conclusions: There is small but statistically significant increase in risk of subsequent diagnosis of colorectal or breast cancer diagnosis in patients with AF. Shared risk factors such as old age or systemic disease processes may explain this association. While the results of this analysis raise interesting questions for future search, these results should not be used as basis to initiate cancer screening for an occult cancer in a patient with AF.

512 Background: The tumor microenvironment in PDA is heterogeneous and immunosuppressive given the presence of regulatory T cells and exhausted effector T cells. Despite the upsurge of effective immunotherapeutic agents (IA) in other tumor types, the role in PDA remains unknown. We conducted a meta-analysis of IA in PDA. Methods: Following PRISMA guidelines, we searched PubMed/MEDLINE, Elsevier/Embase, Wiley/Cochrane Library and ClinicalTrials.gov. Articles were selected per the following criteria: (1) Study participants had a diagnosis of PDA; (2) An IA was used in the trial. Titles, abstracts and full text articles were reviewed by 2 independent reviewers; disagreements were resolved by a third. Data extraction and analysis were performed by 3 independent reviewers. Descriptive analysis, mean, median, confidence interval and forest plots were used for statistical analysis. Results: We found 20,792 studies through the database, 16,105 remained after duplicates were removed and 15,889 were excluded due to irrelevance. Strict inclusion criteria were applied to the full text of 216 articles. The most common reason for exclusion were conference abstracts (44%) and ongoing trials (16%). Fifty-four trials (39 metastatic (met), 12 adjuvant (Ad) and 3 neoadjuvant (nAd) met criteria for further analysis. Age range was 27-86 (median 61) and 52.3% were males. IA included cytokine therapy (33%), peptide vaccines (22%), dendritic cell vaccine (13%), oncolytic viruses (9%), CTLA-4 inhibitors (2%) and others. IA in met-PDA had a median overall survival (mOS) of 8.1 months (ms) and a disease control rate (DCR) of 55.4% (95% CI, 51.85-58.95). There was no statistical difference in DCR among IA subtypes (range 49-60%) (p = 0.22). The mOS of Ad-PDA trials was 25 ms (historically comparable to gemcitabine, p = 0.75) and 18 ms for nAd-PDA. The most common Gr1/2 toxicities were skin reactions, fever, and chills and Gr3/4 were cytopenias, diarrhea, and mucositis. One death occurred due to neutropenic sepsis. Conclusions: IA demonstrates modest efficacy in the treatment of met-PDA albeit exhibits a favorable toxicity profile. Many trial results are available only in abstract format and some are ongoing.

341 Background: Genomes of metastatic pancreatic cancers frequently contain intrachromosomal aberrations indicating DNA repair abnormalities associated with sensitivity to DNA damaging agents such as the platinums. Cisplatin was added to a nab-paclitaxel + gemcitabine regimen, which has been determined to improve survival over gemcitabine alone (NEJM 2013; 369:1691-1703). The objectives are to determine the efficacy and safety of nab-paclitaxel and gemcitabine plus cisplatin in patients with Stage IV pancreatic cancer. Methods: Eligibility criteria included Stage IV adenocarcinoma of the pancreas, no prior chemotherapy for systemic disease, KPS ≥ 70; life expectancy ≥ 12 weeks and measurable disease. Doses are nab-paclitaxel 125 mg/m2 undiluted, gemcitabine 1000 mg/m2 in 500 ml of normal saline (NS), each infused over 30 minutes on days 1 and 8 of a 21 day cycle, along with 3 different dose levels of cisplatin (25, 37.5 or 50 mg/m2) in 500 ml of NS infused over 60 minutes, after the nab-paclitaxel infusion. Pre and post cisplatin hydration was given. The maximum tolerated dose and phase II dose of cisplatin is 25 mg/m2. Results: 25 pts were treated; 24 were evaluable (baseline and ≥ 1 follow up CT scan). The most common drug related grade (gr) 3 - 4 adverse events (AEs), n = 25, were thrombocytopenia 76% (gr 3 = 36%, gr 4 = 40%) with no serious bleeding events, anemia 32% (gr 3 = 32%, gr 4 = 0%), neutropenia 24% (gr 3 = 20%, gr 4 = 4%), infection 20% (gr 3 = 16%, gr 4 = 4%), and diarrhea 16% (gr 3 = 16%, gr 4 = 0%). Peripheral neuropathy ≥ gr 3 was seen in only 1 pt (gr 3 = 4%). Grade 5 AEs were infection (1), cardiac arrest (1), and stroke (1). Median time on therapy was 5.5 months, range (1 – 9.5). By RECIST 1.1 criteria, 2 pts had complete response (8.3%), 15 partial response (62.5%), 4 stable disease (16.7%), and 3 progressive disease (12.5%). Median overall survival to date as of 11/10/16 is 16.5 months. Conclusions: Although a small study, the high response rate and landmark evolving median survival are very encouraging. This regimen is being expanded in patients with stage IV pancreatic cancer, neoadjuvant and adjuvant settings. Clinical trial information: NCT01893801.

Primary Epstein-Barr virus (EBV) infection occurs mainly in adolescents and young adults, with more than 90% of adults having serological evidence of past infection. Primary infection in those over the age of 40 is associated with an atypical and often more severe presentation that can lead to more extensive and invasive, and often unnecessary, diagnostic testing. The incidence of severe EBV-related illness in older adults has been observed to be increasing in industrialized nations. The characteristic presentation of infectious mononucleosis (IM) syndrome in elderly patients (age > 65) is not clearly defined in the literature. Here, we describe a case of primary EBV infection in an 80-year-old female and review the literature regarding primary seroconversion in elderly patients.