Background: The impact of pancreaticoduodenectomy (PD) on absorption of drugs in the duodenum remains largely unknown. We aim to characterize the pharmacokinetics of apixaban in patients who have previously underwent PD. Methods: A single 10 mg dose of apixaban was administered to four volunteers who underwent PD at least 6 months prior. The maximum plasma apixaban concentration (C max ) and area under the plasma concentration time-curve (AUC 0-24, AUC 0-inf ) were compared against healthy historical control subjects (N=12). Geometric mean ratios (GMR) with 90% confidence interval (CI) were calculated for determination of comparative bioequivalence. Results: In PD patients AUC 0-24 and AUC 0-inf were 1861 and 2080 ng•hr/mL, respectively. The GMRs of AUC 0-24 and AUC 0-inf between study subjects and healthy controls were 1.27 (90% CI 0.88-1.83) and 1.18 (90% CI 0.82-1.72). The mean C max of apixaban was 201 ng/mL (SD 15.6) occurring at a median T max of 3.25 hours (range 2.5-4 hours). The GMR of C max between study subjects and healthy controls was 1.12 (90% CI 0.77-1.63). Conclusions: The pharmacokinetic characteristics of apixaban in subjects who have undergone PD are not significantly different from those of healthy controls. No changes in their dosing regimen are recommended. ClinicalTrials.gov Identifier: NCT04191928

TPS235 Background: A significant proportion of patients with GI adenocarcinomas remain at high risk of recurrence despite adjuvant therapies. Guanylyl cyclase C (GUCY2C) is expressed by normal intestinal cells and immunologically compartmentalized. Its overexpression in GI adenocarcinomas makes it an appealing target for anti-cancer therapies. We previously completed a phase I study of the Ad5-GUCY2C-PADRE vaccine in patients (pts) where it was safe and well tolerated (NCT01972737). Pre-existing neutralizing antibodies (NAbs) to the Ad5 vector opposed vaccine-induced immune responses. To overcome this challenge, we generated a GUCY2C vaccine employing a chimeric viral vector composed of the Ad5 capsid and Ad35 fiber protein (Ad5.F35). The extracellular domain of GUCY2C, along with the PADRE CD4+ helper T-cell epitope, were cloned into the Ad5.F35 viral vector to generate a replication-incompetent vaccine. Preclinical studies showed that Ad5.F35-GUCY2C-PADRE was less sensitive to pre-existing Ad5-specific immunity. Methods: This is a Phase 2A, dose-finding, single-center, open-label, randomized trial (NCT04111172) to evaluate the safety and immunogenic activity of three dose levels of Ad5.F35-GUCY2C-PADRE vaccine in adult pts with select solid tumors (colorectal, pancreatic, gastric, esophageal, or small bowel) who are at risk of relapse post definitive surgery and adjuvant therapy. Pts must enroll at 4-24 weeks from completion of standard therapies. Other key eligibility requirements include ECOG status of 0-1 and adequate organ function. Pts are randomized to one of three dose levels (1011 vp or viral particles, 1012 vp, or 5x1012 vp) with stratification by disease type. After completing an initial safety run-in for 9 pts (3 pts in each arm), the study will recruit up to 81 pts in total (27 in each arm). Pts will receive three successive doses of vaccine (4 weeks apart) and will undergo end-of-treatment assessment 4 weeks after their last vaccine. Pts are followed for disease status by scheduled follow-up until 2 years or recurrence, whichever occurs first. An interim futility analysis will be performed after 15 patients have completed treatment in each arm based on the Simon minimax design. Study objectives include assessment of safety and tolerability (primary), as well as T-cell and antibody responses to GUCY2C (secondary). Additional exploratory objectives include evaluating the relationship between NAbs and immune responses to GUCY2C, GUCY2C protein expression in tumors, circulating tumor DNA kinetics in relation to vaccination, and disease-free and overall survival (where applicable). Prespecified safety run-in has been completed without dose limiting toxicities; second stage accrual began in November 2021, and 43 out of 81 pts have been enrolled. Study enrollment is ongoing. Clinical trial information: NCT04111172 .

INTRODUCTION:Colorectal cancer (CRC) is the second leading cause of cancer-related death in the United States. There have been improvements in screening, and therefore overall survival, but patients continue to present at late stages when minimal treatment options are available to them. While some targeted therapies have been introduced, their application is limited by patient-specific tumor characteristics. Additional targets for CRC in patients who present at a late stage, or who experience tumor relapse, need to be identified to continue to improve patient outcomes. AREAS COVERED:This review focuses on emerging pathways and drug targets for the treatment of colorectal cancer. The shift to the cancer stem cell model and potential targets involving Wnt, NF-κB, phosphodiesterases, RAS, and guanylyl cyclase C, are discussed. The current utility of checkpoint inhibitors and evolving immunological options are examined. EXPERT OPINION:Surgery and current systemic cytotoxic therapies are inadequate to appropriately treat the full spectrum of CRC, especially in those patients who present with metastatic or treatment-refractory disease. In addition to the identification of new, more generalizable targets, additional focus is being placed on novel administrations. Immuno-oncologic options and stem cell-targeting therapies for mCRC will become available to patients and may increase survival.

Colorectal cancer remains a major cause of mortality in the USA, despite advances in prevention and screening. Existing therapies focus primarily on generic treatment such as surgical intervention and chemotherapy, depending on disease severity. As personalized medicine and targeted molecular oncology continue to develop as promising treatment avenues, there has emerged a need for effective targets and biomarkers of colorectal cancer. The transmembrane receptor guanylyl cyclase C (GUCY2C) regulates intestinal homeostasis and has emerged as a tumor suppressor. Further, it is universally expressed in advanced metastatic colorectal tumors, as well as other cancer types that arise through intestinal metaplasia. In this context, GUCY2C satisfies many characteristics of a compelling target and biomarker for gastrointestinal malignancies.

IntroductionColorectal cancer (CRC) is the third most common and second most deadly malignancy in the world with an estimated 1. 9 million cases and 0.9 million deaths in 2020. The 5-year overall survival for stage I disease is 92% compared to a dismal 11% in stage IV disease. At initial presentation, up to 35% of patients have metastatic colorectal cancer (mCRC), and 20–50% of stage II and III patients eventually progress to mCRC. These statistics imply both that there is a proportion of early stage patients who are not receiving adequate treatment and that we are not adequately treating mCRC patients.BodyTargeted therapies directed at CRC biomarkers are now commonly used in select mCRC patients. In addition to acting as direct targets, these biomarkers also could help stratify which patients receive adjuvant therapies and what types. This review discusses the role of RAS, microsatellite instability, HER2, consensus molecular subtypes and ctDNA/CTC in targeted therapy and adjuvant chemotherapy.DiscussionGiven the relatively high recurrence rate in early stage CRC patients as well as the continued poor survival in mCRC patients, additional work needs to be done beyond surgical management to limit recurrence and improve survival. Biomarkers offer both a potential target and a predictive method of stratifying patients to determine those who could benefit from adjuvant treatment.

Introduction Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Although overall survival for CRC patients has improved with earlier screening, survival continues to vary substantially across stages. Also, while the introduction of targeted therapies, including VEGF and EGFR inhibitors, has contributed to improving survival, better tools are needed to optimize patient selection and maximize therapeutic benefits. Emerging biomarkers can be used to guide pharmacologic decision-making, as well as monitor treatment response, clarify the need for adjuvant therapies, and indicate early signs of recurrence. This is a narrative review examining the current and evolving use of predictive and prognostic biomarkers in colorectal cancer. Areas covered Areas covered include mutations of the MAPK (KRAS, BRAF) and HER2 pathways and their impacts on treatment decisions. In addition, novel methods for assessing tumor mutations and tracking treatment responses are examined. Expert opinion The standard of care pathway for staging, and treatment selection and surveillance, of CRC will expand to include novel biomarkers in the next 5 years. It is anticipated that these new biomarkers will assist in decision-making regarding selection of targeted therapies and, importantly, in risk stratification for treatment decisions in patients at high risk for recurrence.

Introduction: Colorectal cancer (CRC) is one of the most common forms of cancer worldwide and is the second leading cause of cancer-related death in the United States. Despite advances in early detection, ~25% of patients are late stage, and treated patients have <12% chance of survival after five years. Tumor relapse and metastasis are the main causes of patient death. Cancer stem cells (CSCs) are a rare population of cancer cells characterized by properties of self-renewal, chemo- and radio-resistance, tumorigenicity, and high plasticity. These qualities make CSCs particularly important for metastasic seeding, DNA-damage resistance, and tumor repopulating.Areas Covered: The following review article focuses on the role of CRC-SCs in tumor initiation, metastasis, drug resistance, and tumor relapse, as well as on potential therapeutic options for targeting CSCs.Expert Opinion: Current studies are underway to better isolate and discriminate CSCs from normal stem cells and to produce CSC-targeted therapeutics. The intestinal receptor, guanylate cyclase C (GUCY2C) could potentially provide a unique therapeutic target for both non-stem cells and CSCs alike in colorectal cancer through immunotherapies. Indeed, immunotherapies targeting CSCs have the potential to break the treatment-recurrence cycle in the management of advanced malignancies.

ABSTRACT Introduction Colorectal cancer (CRC) is one of the most-deadly malignancies worldwide. Current therapeutic regimens for CRC patients are relatively generic, based primarily on disease type and stage, with little variation. As the field of molecular oncology advances, so too must therapeutic management of CRC. Understanding molecular heterogeneity has led to a new-found promotion for precision therapy in CRC; underlining the diversity of molecularly targeted therapies based on individual tumor characteristics. Areas covered We review current approaches for the treatment of CRC and discuss the potential of precision therapy in advanced CRC. We highlight the utility of the intestinal protein guanylyl cyclase C (GUCY2C), as a multi-purpose biomarker and unique therapeutic target. Here, we summarize current GUCY2C-targeted approaches for treatment of CRC. Expert opinion The GUCY2C biomarker has multi-faceted utility in medicine. Developmental investment of GUCY2C as a diagnostic and therapeutic biomarker offers a variety of options taking the molecular characteristics of cancer into account. From GUCY2C-targeted therapies, namely cancer vaccines, CAR-T cells, and monoclonal antibodies, to GUCY2C agonists for chemoprevention in those who are at high risk for developing colorectal cancer, the utility of this protein provides many avenues for exploration with significance in the field of precision medicine.

Background Esophageal cancer is the fifth most common cause of cancer-related death in the world1 with a 5-year survival rate of <20%.2 Current therapies result in high toxicity and low efficacy, with as many as 60% of esophageal cancer patients not responding to therapeutics.3 CAR-T cell therapy is a therapeutic that can selectively and robustly target cancer cells and eliminate bulky metastatic disease. Previous studies have shown preclinical success with CAR-T cell therapy targeting the human colorectal cancer antigen guanylyl cyclase C (GUCY2C).4 5 Interestingly, esophageal cancers arising from premalignant metaplasia resembling intestine (intestinal metaplasia, also known as Barrett’s esophagus) are highly prevalent and ectopically express GUCY2C. Thus, we hypothesize that GUCY2C will serve as an effective CAR-T cell therapy target in many esophageal cancer patients. However, the paucity of intestine-like human esophageal cancer models limits exploration of this hypothesis, necessitating development of suitable esophageal cancer models (figure 1). Methods To develop esophageal cancer models for GUCY2C immunotherapy testing, esophageal cancer samples were collected at Thomas Jefferson University Hospital by endoscopic biopsy of treatment-naïve patients or by esophagectomy, primarily in patients previously treated with standard neoadjuvant therapy. Patient-derived xenograft (PDX) models were initiated from samples to establish in vivo models for immunotherapy testing. qRT-PCR, immunoblot, and immunofluorescence were performed to test for GUCY2C expression in primary and PDX specimens. Histopathology was performed to confirm retention of primary tumor features. Results GUCY2C was present in only 2 of 6 esophagectomy samples. Interestingly, those patients with detectable GUCY2C were treatment-naïve, while neoadjuvant-treated patients lacked viable tumor, revealing neoadjuvant therapy as a significant barrier to esophageal cancer model generation. In contrast, of the 3 adenocarcinoma specimens collected by endoscopic biopsy in treatment-naïve patients, 2 express GUCY2C. To date, PDX models have been initiated from 6 total samples and successfully established for 3 samples. This 50% success rate may improve over time as PDX formation is often delayed in many models (>150 days). Importantly, established esophageal adenocarcinoma PDX models were histologically similar to their matched primary tumors and retained GUCY2C expression, integral to their validation as models of GUCY2C immunotherapy testing. Conclusions Several human esophageal adenocarcinoma models were successfully established, primarily from endoscopic biopsy of treatment-naïve patients as neoadjuvant therapy proved to be a significant barrier. These models will be useful to explore GUCY2C-directed CAR-T cell therapies and other novel therapies targeting intestine-like esophageal cancer, prior to testing in early-phase clinical trials. Acknowledgements The authors thank the Translational Research & Pathology Core Facility and the Office of Animal Resources at Thomas Jefferson University for their continued support to make this research possible. The authors would also like to thank the Clinical Research Unit at Thomas Jefferson University for their assistance in the collection of patient specimens. This work was supported by a DeGregorio Family Foundation Award and by the Department of Defense Congressionally Directed Medical Research Programs (W81XWH-17-1-0299, W81XWH-191-0263, and W81XWH-19-1-0067) to AES. SAW is supported by the National Institutes of Health (NIH) (R01 CA204881, R01 CA206026, and P30 CA56036), the Defense Congressionally Directed Medical Research Program W81XWH-17-PRCRP-TTSA, and Targeted Diagnostic & Therapeutics. SAW and AES were also supported by a grant from The Courtney Ann Diacont Memorial Foundation. SAW is the Samuel M.V. Hamilton Professor of Thomas Jefferson University. AZ and MC were supported by NIH institutional award T32 GM008562 for Postdoctoral Training in Clinical Pharmacology. Ethics Approval The study was approved by the Thomas Jefferson University Institutional Review Board (#18D.495) and Institutional Animal Care and use Committee (#01529). References Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin2018;68:394–424. doi:10.3322/caac.21492. Yousefi MS, Sharifi-Esfahani M, Pourgholam-Amiji N, Afshar M, Sadeghi-Gandomani H, Otroshi O, et al. Esophageal cancer in the world: incidence, mortality and risk factors. Biomed Res Ther 2018;5:2504–17. doi:10.15419/bmrat.v5i7.460. Huang F-L, Yu S-J. Esophageal cancer: risk factors, genetic association, and treatment. Asian J Surg 2018;41:210–5. doi:10.1016/j.asjsur.2016.10.005. Magee MS, Abraham TS, Baybutt TR, Flickinger JC, Ridge NA, Marszalowicz GP, et al. Human GUCY2C-targeted chimeric antigen receptor (CAR)-expressing T cells eliminate colorectal cancer metastases. Cancer Immunol Res 2018;6:509–16. doi:10.1158/2326-6066.CIR-16-0362. Magee MS, Kraft CL, Abraham TS, Baybutt TR, Marszalowicz GP, Li P, et al. GUCY2C-directed CAR-T cells oppose colorectal cancer metastases without autoimmunity. Oncoimmunology 2016;5:e1227897. doi:10.1080/2162402X.2016.1227897.

Background: Perioperative administration of intravenous antibiotics is a routine part of total knee arthroplasty. Antibiotic selection is a matter of controversy, and the potential risks and benefits associated with each antibiotic selection need to be considered. The objective of this study is to examine the effects of routine dual antibiotic prophylaxis with both cefazolin and vancomycin on infection and renal failure after primary total knee arthroplasty (TKA) compared with cefazolin alone.Methods: We performed a retrospective review of primary TKA patients for two years before and two years after routine dual antibiotic prophylaxis was implemented at our institution. 1502 patients were included (567 cefazolin-only and 935 dual prophylaxis). Results: 2 patients (0.4%) in the cefazolin-only group had a deep surgical site infection, compared with 13 patients (1.4%) in the dual prophylaxis group (p=0.06). 46 patients (8.1%) in the cefazolin-only group had postoperative renal failure, compared with 36 patients (3.9%) in the dual prophylaxis group (p=0.0006).Discussion and Conclusion: Our results did not support the routine use of vancomycin in primary total joint arthroplasty to decrease periprosthetic joint infection. However, we also did not see any clear harm due to renal failure in the routine use of dual antibiotic prophylaxis.