Yonkus, Jennifer

Objective Pancreatic ductal adenocarcinoma (PDAC) displays a remarkable propensity towards therapy resistance. However, molecular epigenetic and transcriptional mechanisms enabling this are poorly understood. In this study, we aimed to identify novel mechanistic approaches to overcome or prevent resistance in PDAC. Design We used in vitro and in vivo models of resistant PDAC and integrated epigenomic, transcriptomic, nascent RNA and chromatin topology data. We identified a JunD-driven subgroup of enhancers, called interactive hubs (iHUBs), which mediate transcriptional reprogramming and chemoresistance in PDAC. Results iHUBs display characteristics typical for active enhancers (H3K27ac enrichment) in both therapy sensitive and resistant states but exhibit increased interactions and production of enhancer RNA (eRNA) in the resistant state. Notably, deletion of individual iHUBs was sufficient to decrease transcription of target genes and sensitise resistant cells to chemotherapy. Overlapping motif analysis and transcriptional profiling identified the activator protein 1 (AP1) transcription factor JunD as a master transcription factor of these enhancers. JunD depletion decreased iHUB interaction frequency and transcription of target genes. Moreover, targeting either eRNA production or signaling pathways upstream of iHUB activation using clinically tested small molecule inhibitors decreased eRNA production and interaction frequency, and restored chemotherapy responsiveness in vitro and in vivo. Representative iHUB target genes were found to be more expressed in patients with poor response to chemotherapy compared with responsive patients. Conclusion Our findings identify an important role for a subgroup of highly connected enhancers (iHUBs) in regulating chemotherapy response and demonstrate targetability in sensitisation to chemotherapy.

Background A gap remains in the role of neoadjuvant therapy for patients with ILC. Method Single-institution retrospective review of patients with ILC who received neoadjuvant therapy between 2008 and 2019. Results 141 patients met inclusion criteria: 71 neoadjuvant chemotherapy (NACT) and 70 neoadjuvant endocrine therapy (NET). 7/71 (9.9%) patients had a pCR following NACT compared to 1/70 (1.4%) with NET ( P = .063). pCR was observed in 5/18 (27.8%) patients with Her2Neu-positive disease following NACT, compared to 2/53 (3.8%) with Her2Neu-negative disease ( P = .01). For luminal B tumors, median Ki-67 decrease was similar following NACT and NET (18.3 vs 16.3, P = .26). T category decreased in 59 (42.1%) patients following neoadjuvant therapy, increased in 9 (6.4%), and was unchanged in 72 (51.4%). More patients had an increase (28.6%) than decrease (12.1%) in their N category, including 13/60 (21.7%) who were clinically node-negative at diagnosis and identified to have node-positive disease following neoadjuvant therapy, at definitive surgery. Conclusion In Her2Neu-negative ILC, the potential of a pCR with NACT or NET is low. Most patients’ nodal status and tumor size remain unchanged. There is a potential for pathologic stage to be higher at surgery compared to the clinical stage prior to neoadjuvant therapy.

Abstract Background and aims Biliary tract cancers (BTCs) are uncommon, but highly lethal, gastrointestinal malignancies. Gemcitabine/cisplatin is a standard‐of‐care systemic therapy, but has a modest impact on survival and harbors toxicities, including myelosuppression, nephropathy, neuropathy, and ototoxicity. Whereas BTCs are characterized by aberrations activating the cyclinD1/cyclin‐dependent kinase (CDK)4/6/CDK inhibitor 2a/retinoblastoma pathway, clinical use of CDK4/6 inhibitors as monotherapy is limited by lack of validated biomarkers, diffident preclinical efficacy, and development of acquired drug resistance. Emerging studies have explored therapeutic strategies to enhance the antitumor efficacy of CDK4/6 inhibitors by the combination with chemotherapy regimens, but their mechanism of action remains elusive. Approach and results Here, we report in vitro and in vivo synergy in BTC models, showing enhanced efficacy, reduced toxicity, and better survival with a combination comprising gemcitabine/cisplatin and CDK4/6 inhibitors. Furthermore, we demonstrated that abemaciclib monotherapy had only modest efficacy attributable to autophagy‐induced resistance. Notably, triplet therapy was able to potentiate efficacy through elimination of the autophagic flux. Correspondingly, abemaciclib potentiated ribonucleotide reductase catalytic subunit M1 reduction, resulting in sensitization to gemcitabine. Conclusions As such, these data provide robust preclinical mechanistic evidence of synergy between gemcitabine/cisplatin and CDK4/6 inhibitors and delineate a path forward for translation of these findings to preliminary clinical studies in advanced BTC patients.

Abstract Background: Operative maneuvers to increase mesenteric length during ileal pouch-anal anastomosis (IPAA) are frequently utilized in adults, but limited data exist on the need for their use in children. Materials and Methods: A retrospective chart review of children (age <18) considered for IPAA creation at two affiliated tertiary referral centers from 2007 to 2017 was conducted, and patient factors, operative details, and 30-day postoperative complications were abstracted. Body mass index (BMI) was normalized to BMI percentile-for-age-and-sex and classified as underweight (BMI <5th percentile), healthy weight (5th ≤ BMI percentile <85th), or overweight/obese (BMI ≥85th percentile). Maneuvers were identified from operative notes. Univariate analysis and multivariable logistic regression were performed to determine independent factors associated with the use of maneuvers. Results: A total of 94 patients underwent attempt at IPAA creation, which was successful in 91 (97%). Fourteen (15%) of 91 patients were classified as overweight or obese. The 3 failures occurred secondary to inability to reach in 3 patients, with specific mention of patients' obesity in 2 and pouch ischemia in 1. Sixty (66%) patients required maneuvers to lengthen the mesentery. Overweight/obese patients required maneuvers more often than nonoverweight/obese patients (93% versus 61%, P = .03). There were no differences in 30-day maximum Clavien-Dindo scores between patients with and without maneuvers performed ( P = .83). Being overweight/obese was an independent risk factor for requiring maneuvers (odds ratio: 9.3, 95% confidence interval: 1.1–82.8) after adjusting for age, sex, height, operative stage, and surgeon. Conclusion: Surgeons should be prepared to perform mesenteric lengthening maneuvers when operating on pediatric patients to ensure minimal tension on the IPAA, and more so when operating on obese children. Whether these maneuvers have an impact on long-term pouch function is undetermined.

Abstract Purpose: Restoration of intestinal continuity by ileal pouch-anal anastomosis (IPAA) following subtotal colectomy may not require a temporary, protective ileostomy. Diversion contributes to patient discomfort, cost, and additional operative risk at the time of subsequent reversal. We compared the outcomes of pediatric patients undergoing modified two-stage to three-stage IPAA after recovering from subtotal colectomy. Methods: We reviewed children (age <18) who underwent IPAA creation for ulcerative or indeterminate colitis from January 1, 2007 to December 31, 2017. Patient characteristics, operative details, 30-day complications, and postoperative length of stay (LOS) were abstracted. Total LOS for the three-stage group included both the IPAA and the ileostomy reversal operations. Univariate comparisons between patients undergoing modified two-stage and three-stage operations were performed. Results: A total of 43 patients underwent IPAA after subtotal colectomy; 32 (74%) underwent a three-stage approach, and 11 (26%) had a modified two-stage approach. Operative approach was laparoscopic in 33 (77%), planned open in 9 (21%), and converted to open in 1 (2%). Single-incision technique was used in 12 of 33 (36%) laparoscopic cases. Modified two-stage procedures had shorter total median LOS (7 days versus 9 days, P = .005). Incidence of postoperative leak, readmission, return to the operating room, and maximum 30-day Clavien–Dindo scores at the time of IPAA creation did not differ between modified two- and three-stage approaches (all P > .05). Conclusion: The modified two-stage approach to IPAA creation resulted in fewer hospital days compared to the three-stage approach. Considering the risks and patient burdens of diversion, further research is needed to assist in decisions regarding protective ileostomy after completion proctectomy with IPAA.