Transforming the Future of Surgeon-Scientists

OBJECTIVE

To create a blueprint for surgical department leaders, academic institutions, and funding agencies to optimally support surgeon-scientists.

BACKGROUND

Scientific contributions by surgeons have been transformative across many medical disciplines. Surgeon-scientists provide a distinct approach and mindset toward key scientific questions. However, lack of institutional support, pressure for increased clinical productivity, and growing administrative burden are major challenges for the surgeon-scientist, as is the time-consuming nature of surgical training and practice.

METHODS

An American Surgical Association Research Sustainability Task Force was created to outline a blueprint for sustainable science in surgery. Leaders from top NIH-sponsored departments of surgery engaged in video and in-person meetings between January and April 2023. A strength, weakness, opportunities, threats analysis was performed, and workgroups focused on the roles of surgeons, the department and institutions, and funding agencies.

RESULTS

Taskforce recommendations: (1) SURGEONS: Growth mindset : identifying research focus, long-term planning, patience/tenacity, team science, collaborations with disparate experts; Skill set : align skills and research, fill critical skill gaps, develop team leadership skills; DEPARTMENT OF SURGERY (DOS): (2) MENTORSHIP: Chair : mentor-mentee matching/regular meetings/accountability, review of junior faculty progress, mentorship training requirement, recognition of mentorship (eg, relative value unit equivalent, awards; Mentor: dedicated time, relevant scientific expertise, extramural funding, experience and/or trained as mentor, trusted advisor; Mentee : enthusiastic/eager, proactive, open to feedback, clear about goals; (3) FINANCIAL SUSTAINABILITY: diversification of research portfolio, identification of matching funding sources, departmental resource awards (eg, T-/P-grants), leveraging of institutional resources, negotiation of formalized/formulaic funds flow investment from academic medical center toward science, philanthropy; (4) STRUCTURAL/STRATEGIC SUPPORT: Structural: grants administrative support, biostats/bioinformatics support, clinical trial and research support, regulatory support, shared departmental laboratory space/equipment; Strategic: hiring diverse surgeon-scientist/scientists faculty across DOS, strategic faculty retention/ recruitment, philanthropy, career development support, progress tracking, grant writing support, DOS-wide research meetings, regular DOS strategic research planning; (5) COMMUNITY AND CULTURE: Community: right mix of faculty, connection surgeon with broad scientific community; Culture: building research infrastructure, financial support for research, projecting importance of research (awards, grand rounds, shoutouts); (6) THE ROLE OF INSTITUTIONS: Foundation: research space co-location, flexible start-up packages, courses/mock study section, awards, diverse institutional mentorship teams; Nurture: institutional infrastructure, funding (eg, endowed chairs), promotion friendly toward surgeon-scientists, surgeon-scientists in institutional leadership positions; Expectations: RVU target relief, salary gap funding, competitive starting salaries, longitudinal salary strategy; (7) THE ROLE OF FUNDING AGENCIES: change surgeon research training paradigm, offer alternate awards to K-awards, increasing salary cap to reflect market reality, time extension for surgeon early-stage investigator status, surgeon representation on study section, focused award strategies for professional societies/foundations.

CONCLUSIONS

Authentic recommitment from surgeon leaders with intentional and ambitious actions from institutions, corporations, funders, and society is essential in order to reap the essential benefits of surgeon-scientists toward advancements of science.

Identifying the optimal treatment strategy in patients with resectable non-cardia gastric cancer

BACKGROUND

Multimodal treatment strategy including perioperative chemotherapy (PEC), postoperative chemoradiation therapy (POCR), and postoperative chemotherapy (POC) has been accepted as the standard of care in gastric cancer (GC). The ideal sequence and type of therapy remain undetermined.

METHOD

The National Cancer Database was examined from 2006 to 2016 to identify patients with resectable non-cardia gastric cancer. Patient outcomes were compared based on the receipt of PEC, POCR, and POC. This comparison was repeated in a sub-group of patients who received optimal treatment. Optimal treatment was defined as initial chemotherapy within 45 days of diagnosis, resection within 45 days of diagnosis, negative margins, adjuvant chemotherapy within 90 days of resection and standard radiation dose (45 Gy). Kaplan-Meier test, log-rank test, and multivariable analysis (MVA) were performed.

RESULTS

We identified 9589 patients. Median survival was greater in the PEC group followed by POCR and POC (60.6, 42.3, and 31.2 months, respectively). On MVA, factors associated with worse overall survival included age above median (≥ 63 years), Charlson-Deyo score of ≥ 1, non-academic/research program, poorly differentiated/undifferentiated grade, positive margins, and positive lymph nodes. Both PEC and POCR were associated with improved survival when compared to POC (HR 0.78 and 0.79; p < 0.001). When compared with PEC, no significant difference was noted with POCR (HR 1.01; p = 0.987). These results were maintained in optimally treated cohort (n = 3418).

CONCLUSION

In patients with resectable non-cardia gastric cancer, both perioperative chemotherapy and postoperative chemoradiation therapy were associated with improved survival when compared to postoperative chemotherapy. No difference was noted between perioperative chemotherapy and postoperative chemoradiation therapy. These results were maintained in the optimally treated cohort.

Netrin-1 feedforward mechanism promotes pancreatic cancer liver metastasis via hepatic stellate cell activation, retinoid, and ELF3 signaling

The biology of metastatic pancreatic ductal adenocarcinoma (PDAC) is distinct from that of the primary tumor due to changes in cell plasticity governed by a distinct transcriptome. Therapeutic strategies that target this distinct biology are needed. We detect an upregulation of the neuronal axon guidance molecule Netrin-1 in PDAC liver metastases that signals through its dependence receptor (DR), uncoordinated-5b (Unc5b), to facilitate metastasis in vitro and in vivo. The mechanism of Netrin-1 induction involves a feedforward loop whereby Netrin-1 on the surface of PDAC-secreted extracellular vesicles prepares the metastatic niche by inducing hepatic stellate cell activation and retinoic acid secretion that in turn upregulates Netrin-1 in disseminated tumor cells via RAR/RXR and Elf3 signaling. While this mechanism promotes PDAC liver metastasis, it also identifies a therapeutic vulnerability, as it can be targeted using anti-Netrin-1 therapy to inhibit metastasis using the Unc5b DR cell death mechanism.

Does non-metastatic gastric cancer of the cardia warrant a different treatment strategy?

BACKGROUND

Multimodal treatment strategies with surgery as its centerpiece have been accepted as the standard of care in nonmetastatic cardia gastric cancer (CGC). There remains a lack of consensus regarding the optimal multimodal treatment strategy.

METHOD

We queried National Cancer Database from 2004 to 2016 to identify patients with resected nonmetastatic CGC who received perioperative chemotherapy (PEC), postoperative chemoradiation therapy (POCR), or postoperative chemotherapy (POC). A subgroup analysis was performed in optimally treated patients defined as initial chemotherapy within 45 days of diagnosis, resection within 45 days of diagnosis, negative margins, adjuvant chemotherapy within 90 days of resection, and standard radiation dose (45 Gy). Kaplan-Meier, Univariate analysis (UVA), and Multivariable analysis (MVA) were performed.

RESULTS

We identified 2387 patients. Median survival was 38.8 months in the PEC group, 36 months in the POCR group, and 32.3 months in the POC group (p = 0.1025). On UVA, patients treated with PEC had an association with improved survival (HR, 0.83; p = 0.037) when compared with POC. On MVA, no significant difference was noted in overall survival (OS) between PEC, POCR, and POC, similar to subgroup analysis of optimally treated cohort.

CONCLUSION

OS rate in nonmetastatic CGC is not significantly different between patients receiving PEC, POCR, or POC.

HCRN GI16-288: A phase II trial of perioperative CV301 vaccination in combination with nivolumab and systemic chemotherapy for resectable hepatic-limited metastatic colorectal cancer—Preliminary efficacy and correlative results

103

Background: Novel strategies to improve the efficacy of immune checkpoint inhibitors in microsatellite stable (MSS) mCRC are needed. CV301 is a vector-based vaccine that expresses carcinoembryonic antigen (CEA) and mucin 1 (MUC1), and in a phase II study in resected hepatic limited mCRC significantly improved OS compared with unvaccinated contemporary controls. Methods: In this multi-center randomized phase II study, patients with previously untreated resectable hepatic-limited mCRC were randomized to perioperative nivolumab + mFOLFOX +/- CV301 (Arm B) with a primary endpoint of 3-year OS. Treatment included mFOLFOX-nivo (+/- CV) x 4 cycles followed by resection, then 8 more cycles of mFOLFOX-nivo followed by maintenance nivo monthly for two years in both arms, and CV boosters concurrently with mFOLFOX, and then every 3 months for two years in arm B. Secondary endpoints of ORR (following induction pre-resection), PRR, and safety were determined. Correlative analyses included immune cell quantification using Immunoscore and T-cell clonality. Results: 17 patients were enrolled prior to premature closure for slow accrual (8 arm A, 9 arm B). At the time of data cutoff, 5 patients remained on treatment and no deaths had occurred. One patient was removed from study due to protocol non-compliance. The median age was 61, majority were male (59% vs 41%), and ECOG PS 0-1 (71% 0, 17% 1). All patients had complete surgical resection. Four patients (24%) experienced a SAE related to drug. The TRAE rate was 40.3%,. No AEs delayed/prevented surgical resection. The ORR in arm A was 50% (including 4 CR) and 87.5% in arm B (including 7 CR) (p=0.129, NS). There was no significant difference in pathologic response (p=0.9047). Correlative analyses demonstrated the Immunoscore CD3/CD8 predicted response to mFOLFOX + nivolumab, but did not correlate with response to CV301, though CV301 may induce a shift to predominantly cytotoxic CD8+ T cells. While there was no significant difference in T cell repertoire, clonality, fraction (TCFr) or richness, patients in arm B had significant decreases in blood TCFr and increase in tumor TCFr with treatment; those with CR had higher TCFr and clonality. Conclusions: The addition of CV301 to perioperative nivolumab and mFOLFOX was safe, did not delay or prevent surgical resection, and gave a higher response (p=ns due to sample size). Changes in T cells suggest a vaccine response. Clinical trial information: NCT03547999 . [Table: see text]

Surgery in combination with systemic chemotherapy is associated with improved survival in stage IV gallbladder cancer

BACKGROUND

Gallbladder cancer (GBC) is the most common biliary malignancy frequently metastatic at diagnosis with poor prognosis. While surgery remains the standard for early-stage GBC, the role of surgery in patients with metastatic gastrointestinal cancers is expanding due to improvements in systemic therapies. We sought to evaluate the survival of patients with stage IV GBC undergoing surgery in an era of improved multi-agent systemic therapy.

METHODS

A retrospective review of the National Cancer Database was performed. Patients with stage IV GBC who underwent systemic therapy were included. Patients who received radiation therapy, palliative therapy or had missing survival data were excluded. Univariable and multivariable analysis was performed.

RESULTS

4,145 patients were identified between 2004 and 2016. Mean age was 69. Surgery combined with systemic therapy predicted improved median survival compared with chemotherapy alone (11.1mo versus 6.8mo, HR 0.65, p < 0.001). Additionally, receipt of treatment after 2011 predicted improved survival (HR 0.86, p < 0.001). Patients treated with multi-agent chemotherapy in combination with surgery were associated with the greatest hazard ratio benefit (0.40, p < 0.001) versus single agent therapy alone.

CONCLUSION

Patients with stage IV gallbladder cancer treated with a combination of surgery and chemotherapy are associated with an improved overall survival compared to chemotherapy alone. Patients receiving care during the more recent era demonstrated improved survival. These results support a role for surgery in selected patients with stage IV gallbladder cancer receiving chemotherapy.

The Impact of Carbohydrate Antigen 19-9 on Survival in Patients with Clinical Stage I and II Pancreatic Cancer

BACKGROUND

Carbohydrate antigen (CA) 19-9 is a biomarker to monitor treatment effect. A threshold to predict prognostic significance remains undefined. We evaluated the impact of CA19-9 on overall survival (OS) in patients with early-stage pancreatic cancer (PC) utilizing the National Cancer Database (NCDB).

METHODS

The NCDB was queried from 2010 to 2014 to identify patients with clinical stage I-II PC. Patients who had undocumented pretreatment CA19-9 were excluded. Patients were stratified into two cohorts: CA19-9 < 98 U/mL and CA19-9 ≥ 98 U/mL, and further categorized into surgery versus no surgery. Twelve- and 24-month OS rates are reported.

RESULTS

Overall, 32,382 patients (stage I: 12,173; stage II: 20,209) were included. The majority of stage I (52.1%) and II (60%) patients had CA19-9 ≥ 98 U/mL. Stage I-II patients with CA19-9 < 98 U/mL had improved OS rates (stage I: 67.5%, 42.6%; stage II: 59.8%, 32.8%) compared with stage I and II patients with CA19-9 ≥ 98 U/mL (stage I: 50.7%, 26.9%; stage II: 48.1%, 22%). Among resected stage I patients, CA19-9 <98 U/mL was associated with improved OS (< 98: 80.5%, 56%; ≥ 98: 70.2%, 42.8%), and a similar trend was seen in resected stage II patients (< 98: 77.6%, 49.9%; ≥ 98: 71%, 39.2%). Unresected stage I patients with lower CA19-9 had improved OS (< 98: 42.1%, 17.5; ≥ 98: 29.9%, 10%), with similar findings in unresected stage II patients (< 98: 41.1%, 15.3%; ≥ 98: 33.4%, 10.6%).

CONCLUSIONS

Our study demonstrated the prognostic value of CA19-9 in patients with clinical stage I-II PC, with a value < 98 U/mL demonstrating improved survival. Surgery significantly improved survival at 12 and 24 months irrespective of CA19-9.

A review of hepatic epithelioid hemangioendothelioma-Analyzing patient characteristics and treatment strategies

BACKGROUND

Hepatic epithelioid hemangioendothelioma (HEH) is a rare vascular tumor of unknown etiology and unpredictable natural history. To date, no large-scale studies have been published evaluating this disease due to its rare occurrence.

METHODS

The National Cancer Database was reviewed between 2004 and 2016 to identify patients with HEH. Univariate analysis with overall survival (OS) was performed by Cox proportional hazards model. Kaplan-Meier method was used to create OS curves and compared using the log-rank test.

RESULTS

We identified 229 patients with HEH. The majority of patients were female (61.1%), white (84.3%), and had a Charlson-Deyo score of 0 (75%). Chemotherapeutic intervention was seen in 26% of the patients while 33% received surgical intervention in the form of wedge/segmental liver resection (n = 27), hepatectomy lobectomy/extended lobectomy (n = 18), and liver transplant (n = 22). Five-year survival in surgical patients was 90.5%, 66.5% and 81%, respectively (p = 0.485). Age greater than 55 years (hazard ratio [HR], 2.78; p < 0.001), Asian ethnicity compared to white (HR, 2.84; p = 0.012), and a higher Charlson-Deyo score (score 1: HR, 2.28; p < 0.001 and score ≥2: HR, 2.76; p = 0.011) were associated with worse OS.

CONCLUSION

Treatment for HEH remains variable with only a third of the patients undergoing surgery. International collaboration is necessary to determine the optimal treatment for this rare disease.

Tumor microbiome links cellular programs and immunity in pancreatic cancer

Microorganisms are detected in multiple cancer types, including in putatively sterile organs, but the contexts in which they influence oncogenesis or anti-tumor responses in humans remain unclear. We recently developed single-cell analysis of host-microbiome interactions (SAHMI), a computational pipeline to recover and denoise microbial signals from single-cell sequencing of host tissues. Here we use SAHMI to interrogate tumor-microbiome interactions in two human pancreatic cancer cohorts. We identify somatic-cell-associated bacteria in a subset of tumors and their near absence in nonmalignant tissues. These bacteria predominantly pair with tumor cells, and their presence is associated with cell-type-specific gene expression and pathway activities, including cell motility and immune signaling. Modeling results indicate that tumor-infiltrating lymphocytes closely resemble T cells from infected tissue. Finally, using multiple independent datasets, a signature of cell-associated bacteria predicts clinical prognosis. Tumor-microbiome crosstalk may modulate tumorigenesis in pancreatic cancer with implications for clinical management.

Abstract 5851: Negative regulation of p53 by ZnT1

Rationale and Background: p53 is a powerful tumor suppressor protein that also autorepresses by inducing expression of its own negative regulators, such as MDM2. Here we explore another potential mechanism for p53 autorepression, regulation of zinc metabolism. Proper folding of p53 requires zinc binding and cancer-associated mutations in p53 often lower the affinity of the mutant proteins for zinc. Our previous work showed that ZMC1, a zinc metallochaperone, can reactivate certain p53 mutants by raising intracellular zinc concentrations. Here we show that p53 activates transcription of ZnT1. ZnT1 can then export zinc from the cell, which in turn lowers p53 activity.

Methods: To explore the relationship between ZnT1 and p53, we studied several human cancer cell lines under various conditions, including ZnT1 overexpression, ZnT1 silencing, and p53 activation. For silencing gene expression, we used CRISPR-Cas9 with a lentiviral vector to knock out ZnT1 and also employed shRNAs to knockdown expression of p53 or ZnT1. To analyze the relationship between TP53 and ZnT1 genes in clinical samples, data from cBioPortal were examined.

Results: ZnT1 transcription increased after p53 was activated in several p53+ cell lines but did not increase in isogenic p53-null cell lines, suggesting that ZnT1 transcription is dependent on p53. p53 also bound to the ZnT1 promoter by chromatin immunoprecipitation assay, and activated transcription of a ZnT1/luciferase promoter fusion. Overexpression of ZnT1 decreased p21 transcription, indicating lowered p53 function; conversely, knockdown of ZnT1 increased p21 transcription. By cBioPortal analysis, ZnT1 gene amplifications were mutually exclusive with TP53 gene mutations in breast and lung tumors.

Conclusion: These data suggest that autorepression of p53 occurs in part due to lowered intracellular zinc caused by upregulation of ZnT1.

Citation Format: Ben Brik, Kathleen Carino, Wade Narrow, Chris R. Harris, Xin Yu, Darren R. Carpizo. Negative regulation of p53 by ZnT1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5851.

Abstract 916: Dec2, a circadian rhythm gene is necessary for disseminated tumor cell survival in a novel murine model of pancreatic cancer dormancy

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a proclivity for early metastasis. Resection remains the only chance for long term survival though most patients die from metastatic recurrence. While most patients recur within the first two years, many develop recurrence much later indicating they harbor dormant disseminated tumor cells (dDTCs). Currently there are no murine models which recapitulate this disease pattern and as a result pancreatic cancer dormancy is poorly understood. We sought to better understand PDAC dormancy using a novel murine model of human pancreatic cancer from which we investigate the genetic and molecular contributions to dormancy. A model of resected PDAC was developed using murine PDAC cells expressing luciferase/mCherry orthotopically implanted into FVB hosts. Primary tumors are resected after 4 weeks and mice followed for recurrence. dDTCs’ are harvested from the livers of mice without evidence of recurrence by fluorescence activated cell sorting (FACS) and subjected to transcriptomic profiling using single cell RNA sequencing. Dec2’s contribution to dormancy was evaluated by overexpression and knockout using CRISPR. Overall survival in the mouse model mirrored 41,552 stage I, II PDAC patients from the National Cancer Database with similar frequency and location of recurrence. One third of mice exhibited latent recurrence with median survival of 568 days before succumbing to recurrence. These mice were used to study dDTCs. Transcriptomic profiling of FACS sorted dDTCs revealed a distinct transcriptome from primary tumors and early recurrences, indicating cell plasticity. dDTCs exhibited decreased proliferation markers and upregulated genes involved in immune modulation, cell stemness, linoleic acid (LA) metabolism, and Dec2. dDTCs were resistant to chemotherapy. An in vitro model of dormancy was constructed in which LA treatment inhibited cell proliferation and increased Dec2. Dec2 overexpression resulted in cell quiescence, and knockout increased apoptosis with LA exposure. Dec2-KO cells implanted in the murine model dramatically improved survival compared to Dec-WT cells (Dec2-WT median survival 30 days, Dec2-KO median survival was not reached, p=0.013). Livers of mice in the resection model where Dec2-KO cells were used had decreased dDTC burden with fewer mice showing detectable luciferase gDNA (p&lt;0.01) indicating that loss of Dec2 reduced survival of dDTC’s. This is the first murine model of pancreatic cancer dormancy that recapitulates outcomes of resected PDAC patients. These studies reveal pancreatic cancer dormancy is characterized by a distinct, plastic cellular state characterized by chemotherapy resistance. Dec2 appears required for dormancy, its absence leads to disseminated tumor cell apoptosis. This suggests Dec2 may be a therapeutic target in pancreatic cancer dormancy.

Citation Format: Anthony S. Casabianca, Chris Harris, Crissy Dudgeon, Darren R. Carpizo. Dec2, a circadian rhythm gene is necessary for disseminated tumor cell survival in a novel murine model of pancreatic cancer dormancy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 916.

Surgery is Associated With Improved Overall Survival in Patients With Metastatic Gastric Cancer: A National Cancer Database Analysis

BACKGROUND

The 5-year overall survival (OS) rate for patients with metastatic gastric cancer (mGC) is 5.3%. Surgery for mGC is controversial.

METHODS

We identified all mGC patients who received chemotherapy using the National Cancer Database (2004-2015). Patients were grouped according to surgery of: (1) the primary site (PS) only, (2) primary and distant sites (PDS), (3) distant site only (DS), or (4) no surgery (NS). A propensity score adjustment and multivariate regression was used to compare OS.

RESULTS

Overall, 18,772 patients met the inclusion criteria: (1) PS (n = 962, 5.1%), (2) PDS (n = 380, 2.1%), (3) DS (n = 984, 5.2%), and 16,446 NS (87.6%). Surgery was associated with improved OS in the PS and PDS groups (hazard ratios: .489 (95% CI: .376-.636); .583 (95% CI: .420-.811), P < .001) (median OS 15.8 and 15.9 months vs 8.6 for NS patients, respectively).

CONCLUSIONS

Gastrectomy with or without metastasectomy is associated with improved survival in stage IV gastric cancer patients receiving chemotherapy. This warrants further prospective studies.

p53 and Zinc: A Malleable Relationship

A large percentage of transcription factors require zinc to bind DNA. In this review, we discuss what makes p53 unique among zinc-dependent transcription factors. The conformation of p53 is unusually malleable: p53 binds zinc extremely tightly when folded, but is intrinsically unstable in the absence of zinc at 37°C. Whether the wild-type protein folds in the cell is largely determined by the concentration of available zinc. Consequently, zinc dysregulation in the cell as well as a large percentage of tumorigenic p53 mutations can cause p53 to lose zinc, misfold, and forfeit its tumor suppressing activity. We highlight p53’s noteworthy biophysical properties that give rise to its malleability and how proper zinc binding can be restored by synthetic metallochaperones to reactivate mutant p53. The activity and mechanism of metallochaperones are compared to those of other mutant p53-targeted drugs with an emphasis on those that have reached the clinical trial stage.

The impact of CA 19-9 on survival in patients with clinical stage I pancreatic cancer

606

Background: Standard of care for early-stage resectable pancreatic cancer (PC) includes a combination of surgical resection and chemotherapy. Frequently, CA 19-9 is used as a biomarker to monitor treatment effect and has prognostic significance. We evaluated the impact of CA 19-9 on overall survival (OS) in patients with clinical stage I PC (cT1N0 and cT2N0) utilizing the National Cancer Database (NCDB). Methods: The NCDB was queried between 2010 and 2014 to identify patients with clinical stage I PC. Patients who had missing or undocumented CA 19-9 value at diagnosis were excluded. Demographic and clinical characteristics were analyzed. Patients were stratified into two cohorts based on the CA 19-9 value at diagnosis – CA 19-9 < 98 U/mL and CA 19-9 > 98 U/mL. Univariable and multivariable analyses were performed, and variables associated with OS were identified. Kaplan-Meier survival curves were computed to compare the OS between the two cohorts. Results: A total of 12,480 patients met our inclusion criteria. A majority of patients were female (51.9%), white (84.4%), with a median age of 70 years. Nearly, half the patients received care in an academic/research program (49.5%). A majority of patients had tumors located in the head of the pancreas (71.9%), and received single-agent (35.1%) or multiagent (22.9%) chemotherapy. Over half the patients (6505 patients, 52.1%) had a CA 19-9 value > 98 U/mL. A CA 19-9 value > 98 U/mL in patients predicted a significantly shorter median OS of 12.1 months compared to 19.4 months in patients with a CA 19-9 < 98 U/mL, p<0.0001 (Table). The 5-year OS rate was 9.9% in patients with a CA 19-9 value of > 98 U/mL compared to a 5-year OS rate of 18.1% for patients with a CA 19-9 value < 98 U/mL. On multivariable analysis, CA 19-9 > 98 compared to CA 19-9 < 98 (HR 1.53, p<0.001) and black race compared to white race (HR 1.10, p<0.001) was associated with worse survival, whereas tumor location in the body and tail compared to the head (HR 0.82, p<0.001), single-agent (HR 0.55, p<0.001) and multiagent (HR 0.55, p<0.001) chemotherapy compared to no chemotherapy, independently predicted improved OS. Conclusions: This is the first National Cancer Database study to demonstrate the prognostic value of CA 19-9 in patients with clinical stage I pancreatic cancer, with a value < 98 U/mL predicting improved survival. Clinical stage I pancreatic cancer patients appear to derive a significant benefit from chemotherapy, including single and multiagent chemotherapy, irrespective of the CA 19-9 value.[Table: see text]

Defining the role of systemic therapy in resectable pancreatic acinar cell carcinoma

INTRODUCTION

Following resection of pancreatic acinar cell carcinoma (PACC) distant recurrence remains high. We utilized the national cancer database (NCDB) to evaluate the role of systemic therapy in early-stage resected PACC.

METHODS

We queried the NCDB registry from 2004 to 2015 for patients with pathologic stage I-IIB PACC. For each stage, patients who underwent surgery alone (SA) were compared to patients who received systemic and/or radiation therapy in addition to surgery (surgery + therapy [S + T]).

RESULTS

A total of 271 patients (101 pI, 81 pIIA, and 89 pIIB) were analyzed. Of all clinically node positive patients (n = 41), the majority (n = 32, 78%) had node-positive disease at resection (pIIB). SA was performed in 112 patients (41.3%), whereas 159 (58.7%) patients received S + T. There was no difference in overall survival (OS) between S + T and SA with respect to pI or pIIA disease. In pIIB disease, S + T was associated with improved OS compared to SA (34.9 vs. 16.9 months, p = 0.031). Single-agent chemotherapy was associated with improved OS for pIIB disease when compared to SA (hazard ratio: 0.38, 95% confidence interval: 0.16, 0.83).

CONCLUSION

In resectable PACC, the survival benefit of adjuvant therapy is limited to pathologic stage IIB disease. This benefit is evident even in patients treated with single-agent chemotherapy.

Urea Denaturation, Zinc Binding, and DNA Binding Assays of Mutant p53 DNA-binding Domains and Full-length Proteins

In the cell, the thermodynamic stability of a protein - and hence its biological activity - can change dramatically as a result of perturbations in its amino acid sequence and the concentration of stabilizing ligands. This interplay is particularly evident in zinc-binding transcription factors such as the p53 tumor suppressor, whose DNA-binding activity can critically depend on levels of intracellular zinc as well as point mutations that alter either metal binding or folding stability. Separate protocols exist for determining a protein's metal affinity and its folding free energy. These properties, however, are intimately connected, and a technique is needed to integrate these measurements. Our protocols employ common non-fluorescent and fluorescent zinc chelators to control and report on free Zn²⁺ concentration, respectively, combined with biophysical assays of full-length human p53 and its DNA-binding domain. Fitting the data to equations that contain stability and metal-binding terms results in a more complete picture of how metal-dependent proteins can lose and gain DNA-binding function in a range of physiological conditions. Graphic abstract: Figure 1.Raising intracellular zinc can restore tumor-suppressing function to p53 that has been unfolded by missense mutation or cellular conditions.

Genetic Drivers of Ileal Neuroendocrine Tumors

Simple Summary

Although ileal neuroendocrine tumors are the most common tumors of the small intestine, they are not well-defined at the genetic level. Unlike most cancers, they have an unusually low number of mutations, and also lack recurrently mutated genes. Moreover ileal NETs have been difficult to study in the laboratory because there were no animal models and because cell lines were generally unavailable. But recent advances, including the first ileal NET mouse model as well as methods for culturing patient tumor samples, have been described and have already helped to identify IGF2 and CDK4 as two of the genetic drivers for this tumor type. These advances may help in the development of new treatments for patients.

Abstract

The genetic causes of ileal neuroendocrine tumors (ileal NETs, or I-NETs) have been a mystery. For most types of tumors, key genes were revealed by large scale genomic sequencing that demonstrated recurrent mutations of specific oncogenes or tumor suppressors. In contrast, genomic sequencing of ileal NETs demonstrated a distinct lack of recurrently mutated genes, suggesting that the mechanisms that drive the formation of I-NETs may be quite different than the cell-intrinsic mutations that drive the formation of other tumor types. However, recent mouse studies have identified the IGF2 and RB1 pathways in the formation of ileal NETs, which is supported by the subsequent analysis of patient samples. Thus, ileal NETs no longer appear to be a cancer without genetic causes.

Delayed cytokine release syndrome after neoadjuvant nivolumab: a case report and literature review

Aim: Cytokine release syndrome (CRS) is an infrequently described immune-related adverse event of checkpoint inhibitors (CPI). CPI-induced CRS typically presents with fevers, hemodynamic instability and organ dysfunction within 2 weeks of the last treatment cycle. Case study: We report an unusual case of delayed and severe CRS occurring postoperatively in a patient with hepatic-limited metastatic colorectal cancer who received neoadjuvant immunotherapy. After a negative workup for alternative causes, he received prolonged corticosteroid treatment with symptom resolution. Conclusion: CPI-induced CRS can mimic sepsis and clinicians should maintain a high-index of suspicion to diagnose this immune-related adverse event early and initiate appropriate treatment. As use of perioperative immunotherapy increases, the potential role of surgery to trigger CRS in this case warrants further investigation.

Association of suboptimal lymph node yield with inferior survival in resected stage 1 colon cancer patients

3601

Background: A minimum of 12 lymph nodes are required during colectomy to accurately stage colon cancer. Prior studies in stage II colon cancer patients demonstrate association of inadequate lymph node examination (LNE) with worse overall survival (OS). No large-scale analogous studies related to LNE have been completed in stage I colon cancer patients. We evaluated patients with stage I colon cancer to determine the association between lymph node yield and OS. Methods: We reviewed the National Cancer Database between 2004-2015 to identify patients with pathologic stage I colon cancer (pT1N0 or pT2N0) who underwent definitive surgical resection. Patients who received radiation therapy or had missing values were excluded. Clinical and demographic characteristics were analyzed. Based on LNE, patients were stratified into 4 cohorts (LNE, 0-5, 6-11, 12-19, 20+) and 2 cohorts (0-11, 12+). Univariable and multivariable analyses were performed to identify variables associated with OS. Kaplan-Meier survival curves were computed to compare the cohorts. Results: We included 81,909 patients for analyses. Median age at diagnosis was 69. A majority were female (51.1%), white (83.8%), received care in a community cancer program (59.5%), and had a Charlson-Deyo score of 0 (66.6%). Only 0.7% of patients had a margin positive resection with a 2.5cm median tumor size. Patients were similarly split between pT1 and pT2. Suboptimal LNE was noted in 27.8% of patients. Patients with LNE were distributed - 10.7% (0-5), 17.1% (6-11), 43.4% (12-19) and 28.9% (20+). Postoperative 30-day mortality was 1.9%. 521 (0.7%) received systemic therapy. Ten-year survival in patients with 0-5 LNE was 52.8% compared to 60.1% with 20+ LNE. On multivariable analyses, patients aged ≥ 69, male sex, increasing tumor size (quartile), pT2 staging and a higher Charlson-Deyo score independently predicted worse OS (p < 0.001). LNE categories were significantly associated with OS (p < 0.001) (Table). On regrouping into 0-11 and 12+ LNE groups, 0-11 LNE group predicted worse OS (HR 1.22, p < 0.001). On multivariable analysis, the above variables continued to show similar association with OS (p < 0.001). Conclusions: Our study demonstrates that lymph node yield is associated with overall survival in patients with stage 1 colon cancer undergoing surgical resection. Furthermore, patients with suboptimal lymph node yield are associated with an inferior overall survival compared to those with optimal lymph node yield. Moreover, this study finds that a large number of patients ( > 25%) continue to have suboptimal lymph node yields. Future efforts should focus on improving the lymph node yield with optimal efforts by the surgeon and pathologist. Future studies should examine the role of systemic therapy in patients with inadequate lymph node yield.[Table: see text]

Benzothiazolyl and Benzoxazolyl Hydrazones Function as Zinc Metallochaperones to Reactivate Mutant p53

We identified a set of thiosemicarbazone (TSC) metal ion chelators that reactivate specific zinc-deficient p53 mutants using a mechanism called zinc metallochaperones (ZMCs) that restore zinc binding by shuttling zinc into cells. We defined biophysical and cellular assays necessary for structure-activity relationship studies using this mechanism. We investigated an alternative class of zinc scaffolds that differ from TSCs by substitution of the thiocarbamoyl moiety with benzothiazolyl, benzoxazolyl, and benzimidazolyl hydrazones. Members of this series bound zinc with similar affinity and functioned to reactivate mutant p53 comparable to the TSCs. Acute toxicity and efficacy assays in rodents demonstrated C1 to be significantly less toxic than the TSCs while demonstrating equivalent growth inhibition. We identified C85 as a ZMC with diminished copper binding that functions as a chemotherapy and radiation sensitizer. We conclude that the benzothiazolyl, benzoxazolyl, and benzimidazolyl hydrazones can function as ZMCs to reactivate mutant p53 in vitro and in vivo.

Neoadjuvant therapy is associated with lower margin positivity rates after Pancreaticoduodenectomy in T1 and T2 pancreatic head cancers: An analysis of the National Cancer Database

BACKGROUND

Neoadjuvant therapy (NAT) for T1/T2 pancreatic adenocarcinoma (PDAC) prior to pancreaticoduodenectomy remains controversial. We compared positive margin rates in patients with clinical T1&T2 tumors who did and did not receive NAT.

METHODS

The National Cancer Database (NCDB) found clinical T1&T2 PDAC patients who underwent pancreaticoduodenectomy from 2004 to 2014. Univariate and multivariate regression determined factors associated with a positive margin and survival.

RESULTS

9795 patients underwent surgery for clinical T1 or T2 pancreatic head adenocarcinoma. 8472 patients had data regarding use of neoadjuvant and adjuvant therapies; of which, 774 (9.1%) received NAT and 435 (5.1%) received both chemotherapy and radiation therapy. NAT was found to lower positive margin rates from 21.8 to 15.5% (p < 0.0001) and when radiation was added this rate dropped to 13.4%. Positive margins were associated with worse overall survival (14.9 vs. 23.9 months; HR 1.702, p < 0.0001).

CONCLUSIONS

NAT is associated with a reduced positive margin rate in patients with T1 and T2 tumors. These findings support ongoing and future clinical trials of NAT in T1 and T2, early stage PDAC to determine impacts on survival.

Zinc shapes the folding landscape of p53 and establishes a pathway for reactivating structurally diverse cancer mutants

Missense mutations in the p53 DNA-binding domain (DBD) contribute to half of new cancer cases annually. Here we present a thermodynamic model that quantifies and links the major pathways by which mutations inactivate p53. We find that DBD possesses two unusual properties—one of the highest zinc affinities of any eukaryotic protein and extreme instability in the absence of zinc—which are predicted to poise p53 on the cusp of folding/unfolding in the cell, with a major determinant being available zinc concentration. We analyze the 20 most common tumorigenic p53 mutations and find that 80% impair zinc affinity, thermodynamic stability, or both. Biophysical, cell-based, and murine xenograft experiments demonstrate that a synthetic zinc metallochaperone rescues not only mutations that decrease zinc affinity, but also mutations that destabilize DBD without impairing zinc binding. The results suggest that zinc metallochaperones have the capability to treat 120,500 patients annually in the U.S.

Does Major Pancreatic Surgery Have Utility in Nonagenarians with Pancreas Cancer?

OBJECTIVE

This study aims to define the role of surgery and assess different therapies for nonagenarians with localized, nonmetastatic pancreatic adenocarcinoma (PDAC).

METHODS

The National Cancer Database (NCDB) was queried for patients ≥ 90 years of age with nonmetastatic, localized PDAC from 2004-2016. Postoperative mortality was assessed at 30 and 90 days in patients receiving pancreatoduodenectomy or total pancreatectomy. Overall survival (OS) was compared between three treatment groups: surgery alone, chemotherapy alone, and chemoradiation (chemoRT) alone.

RESULTS

Of 380,524 patients with PDAC, 98 patients ≥ 90 years of age underwent curative-intent resection; 55% were female and 75% had a Charlson-Deyo comorbidity score of 0. A total of 17% received postoperative chemotherapy, 51.1% had poorly differentiated tumors with a median tumor size of 3 cm, 55.1% had positive lymph nodes, and 19.4% had positive resection margins. Postoperative median length of stay was 11 days. Postoperative 30- and 90-day mortality was 10.0% and 18.9%, respectively. Median OS for the surgery alone group was 11.6 months compared with 20.4 months in those receiving adjuvant therapy (p = 0.01). Among nonoperative PDAC patients, median OS in patients receiving chemotherapy only (n = 207) was 7.2 months, while chemoRT only (n = 100) was similar to surgery only (11 versus 11.6 months, p = 0.97).

CONCLUSIONS

Even in well-selected nonagenarians, pancreatoduodenectomy or total pancreatectomy carries a high mortality rate. While adjuvant therapy after resection provides the best survival, it is seldom achieved, and chemoRT alone affords identical survival statistics as surgery alone. These data suggest it is reasonable to consider chemoRT as initial therapy, then reassess candidacy for resection if performance status allows.

Conditional survival analysis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide with an approximate 5-year survival of greater than 50% in patients after surgical resection. Survival estimates have limited utility for patients who have survived several years after initial treatment. We analyzed how conditional survival (CS) after curative-intent surgery for HCC predicts survival estimates over time.

METHODS

NCDB (2004-2014) was queried for patients undergoing definitive surgical resection for HCC. Cumulative overall survival (OS) was calculated using the Kaplan-Meier method, and CS at x years after diagnosis was calculated as CS1  = OS (X+5) /OS(X) .

RESULTS

The final analysis encompassed 11 357 patients. Age, negative margin status, grade severity and radiation before surgery were statistically significant predictors of cumulative overall conditional survival (P ≤ .0001). Overall unconditional 5-year survival was 65.7%, but CS estimates were higher. A patient who has already survived 3 years has an additional 2-year, or 5-year CS, estimate of 86.96%.

CONCLUSION

Survival estimates following hepatic resection in HCC patients change according to survival time accrued since surgery. CS estimates are improved relative to unconditional OS. The impact of different variables influencing OS is likewise nonlinear over the course of time after surgery.

Abstract 3432: Zinc metallochaperones for mutant p53 reactivation in cancer therapeutics

The p53 transcription factor functions as one of cancer's most potent tumor suppressors and is the most frequently mutated gene in human cancer. Restoration of wild type structure and function (so-called reactivation) of the high levels of the deficient mutant p53 protein with a small molecule is a highly sought after goal in anti-cancer drug development. We discovered a new class of small molecule zinc chelators named zinc metallochaperones (ZMCs) that reactivate zinc deficient mutant p53 through a novel mechanism by refolding p53 protein and inducing a p53 mediated apoptotic program. We identified the role of cellular zinc homeostasis as the OFF switch in ZMC pharmacodynamics indicating that a brief period of p53 mutant reactivation is sufficient for on-target efficacy. We conducted pre-clinical pharmacokinetic (PK), pharmacodymanic (PD) and efficacy studies in the murine pancreatic cancer (KPC) and BRCA1-deficient breast cancer models and found that ZMC1 and its new formulation of the drug in complex with zinc improved survival and inhibited tumor growth specifically for the zinc deficient allele. Using the BRCA1-deficient breast cancer model, we observed a highly synergistic effect of ZMC1 and the PARP inhibitor olaparib. Olaparib is now approved for the treatment of advanced BRCA1/2 mutant ovarian cancers, and recent clinical data also support its efficacy in BRCA1/2 mutant breast cancers. However acquired resistance to PARP inhibitors is inevitable in most advanced cancers. We investigated the ZMC therapeutic efficacy and found that the cell lines derived from olaparib resistant tumors are still sensitive to ZMC1 treatment. We are currently investigating the mechanism and testing the combination in vivo. In addition, we explored synergistic combinations of ZMC1 and other chemotherapy drugs based on its mechanism of action including ZMC1 with MDM2 antagonists and BCL2 antagonists. Overall, our findings indicate that the mutant p53 reactivational activity of ZMCs is governed by a unique ON/OFF switch mechanism that allows the compounds to be effective with a brief exposure to avoid the off target toxicities. The targeted and synergistic combinatorial treatments represent a significant departure from the traditional paradigm for developing a targeted molecular therapeutic in cancer.

Citation Format: Xin Yu, Bing Na, Saif Zaman, Tracy Withers, John Gilleran, Alan J. Blayney, Anthony F. Bencivenga, Adam R. Blanden, Yue Liu, David A. Boothman, Stewart N. Loh, S. David Kimball, Shridar Ganesan, Darren R. Carpizo. Zinc metallochaperones for mutant p53 reactivation in cancer therapeutics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3432.

Subcategorizing T1 Staging in Pancreatic Adenocarcinoma Predicts Survival in Patients Undergoing Resection: An Analysis of the National Cancer Database

Purpose: According to the American Joint Committee on Cancer (AJCC) 7th edition, T1 staging of pancreatic adenocarcinoma (PC) is defined as tumor limited to the pancreas, ≤2 cm. The AJCC 8th edition subcategorizes T1 staging into T1a (≤5 mm), T1b (≤1 cm), and T1c (≤2 cm) for PC despite the absence of supporting evidence. We sought to determine whether this new subcategorization has prognostic significance. Methods: A retrospective review of patients undergoing definitive surgery for PC was performed by using the National Cancer Database (NCDB) from 2004 to 2014. Kaplan-Meier survival was computed for the subcategories. Multivariable analysis (MVA) was performed by using stepwise regression. Results: The NCDB captured 41,552 stages I and II patients who underwent definitive surgery for PC in this 10-year period. A total of 2090 of these patients were pathological T1N0. The 5-year overall survival (OS) for patients with T1a (n = 319), T1b (n = 296), and T1c (n = 1309) PC was 68.8%, 57%, and 46.6%, respectively. This subcategorization lost significance on MVA and when focused on T1N1-2 patients. Recategorizing T stage into T1a (≤1 cm) and T1b (≤2 cm) resulted in statistical significance on MVA. Conclusion: Subcategorization of the T1 stage into T1a, T1b, and T1c in resected PC does differentiate OS in patients with node-negative disease. We support the AJCC 8th edition T1 stage subcategorization, while understanding that it does not differentiate OS on MVA. When this is further subcategorized into T1a (≤1 cm) and T1b (≤2 cm), it predicts OS in resected, node-negative patients on MVA.

IGF2 drives formation of ileal neuroendocrine tumors in patients and mice

By the strictest of definitions, a genetic driver of tumorigenesis should fulfill two criteria: it should be altered in a high percentage of patient tumors, and it should also be able to cause the same type of tumor to form in mice. No gene that fits either of these criteria has ever been found for ileal neuroendocrine tumors (I-NETs), which in humans are known for an unusual lack of recurrently mutated genes, and which have never been detected in mice. In the following report, we show that I-NETs can be generated by transgenic RT2 mice, which is a classic model for a genetically unrelated disease, pancreatic neuroendocrine tumors (PNETs). The ability of RT2 mice to generate I-NETs depended upon genetic background. I-NETs appeared in a B6AF1 genetic background, but not in a B6 background nor even in an AB6F1 background. AB6F1 and B6AF1 have identical nuclear DNA but can potentially express different allelic forms of imprinted genes. This led us to test human I-NETs for loss of imprinting, and we discovered that the IGF2 gene showed loss of imprinting and increased expression in the I-NETs of 57% of patients. By increasing IGF2 activity genetically, I-NETs could be produced by RT2 mice in a B6 genetic background, which otherwise never developed I-NETs. The facts that IGF2 is altered in a high percentage of patients with I-NETs and that I-NETs can form in mice that have elevated IGF2 activity, define IGF2 as the first genetic driver of ileal neuroendocrine tumorigenesis.

Rethinking the Role of Radiation Therapy in the Treatment of Unresectable Hepatocellular Carcinoma: A Data Driven Treatment Algorithm for Optimizing Outcomes

Hepatocellular carcinoma (HCC) is the second most common cause of cancer death worldwide, with a majority of HCC patients not suitable for curative therapies. Approximately 70% of initially diagnosed patients cannot undergo surgical resection or transplantation due to locally advanced disease, poor liver function/underlying cirrhosis, or additional comorbidities. Local therapeutic options for patients with unresectable HCC, who are not suitable for thermal ablation, include transarterial embolization (bland, chemoembolization, radioembolization) and/or external beam radiation therapy (EBRT). Regarding EBRT specifically, technological advancements provide a means for safe and effective radiotherapy delivery in a wide spectrum of HCC patients. In multiple prospective studies, EBRT delivery in a variety of different fractionation schemes or in combination with transcatheter arterial chemoembolization (TACE) demonstrate improved outcomes, particularly with combination therapy. The Barcelona Clinic Liver Cancer classification provides a framework for treatment selection; however, given the growing complexity of treatment strategies, this classification system tends to simplify decision-making. In this review, we discuss the current literature regarding unresectable HCC and propose a modified treatment algorithm that emphasizes the role of radiation therapy for Child-Pugh score A or B patients with ≤3 nodules measuring >3 cm, multinodular disease or portal venous thrombosis.

Combinatorial Therapy of Zinc Metallochaperones with Mutant p53 Reactivation and Diminished Copper Binding

Chemotherapy and radiation are more effective in wild-type (WT) p53 tumors due to p53 activation. This is one rationale for developing drugs that reactivate mutant p53 to synergize with chemotherapy and radiation. Zinc metallochaperones (ZMC) are a new class of mutant p53 reactivators that restore WT structure and function to zinc-deficient p53 mutants. We hypothesized that the thiosemicarbazone, ZMC1, would synergize with chemotherapy and radiation. Surprisingly, this was not found. We explored the mechanism of this and found the reactive oxygen species (ROS) activity of ZMC1 negates the signal on p53 that is generated with chemotherapy and radiation. We hypothesized that a zinc scaffold generating less ROS would synergize with chemotherapy and radiation. The ROS effect of ZMC1 is generated by its chelation of redox active copper. ZMC1 copper binding (K _Cu) studies reveal its affinity for copper is approximately 10⁸ greater than Zn²⁺ We identified an alternative zinc scaffold (nitrilotriacetic acid) and synthesized derivatives to improve cell permeability. These compounds bind zinc in the same range as ZMC1 but bound copper much less avidly (10⁶- to 10⁷-fold lower) and induced less ROS. These compounds were synergistic with chemotherapy and radiation by inducing p53 signaling events on mutant p53. We explored other combinations with ZMC1 based on its mechanism of action and demonstrate that ZMC1 is synergistic with MDM2 antagonists, BCL2 antagonists, and molecules that deplete cellular reducing agents. We have identified an optimal Cu²⁺:Zn²⁺ binding ratio to facilitate development of ZMCs as chemotherapy and radiation sensitizers. Although ZMC1 is not synergistic with chemotherapy and radiation, it is synergistic with a number of other targeted agents.

Therapeutic targeting of BRCA1 and TP53 mutant breast cancer through mutant p53 reactivation

Triple negative breast cancer (TNBC) is an aggressive subset for which effective therapeutic approaches are needed. A significant proportion of TNBC patients harbor either germline or somatic mutations in BRCA1, or epigenetic silencing of BRCA1, which renders them deficient in DNA repair. Virtually all BRCA1 deficient breast cancers harbor mutations in TP53 suggesting that inactivation of p53 is a requirement for tumor progression in the setting of BRCA1 deficiency. Due to this dependency, we hypothesized that restoring wild type p53 function in BRCA1 deficient breast cancer would be therapeutic. The majority of TP53 mutations are missense, which generate a defective protein that potentially can be targeted with small molecules. Zinc metallochaperones (ZMCs) are a new class of anti-cancer drugs that specifically reactivate zinc-deficient mutant p53 by restoring zinc binding. Using ZMC1 in human breast cancer cell lines expressing the zinc deficient p53R175H, we demonstrate that loss of BRCA1 sensitizes cells to mutant p53 reactivation. Using murine breast cancer models with Brca1 deficiency, we demonstrate that ZMC1 significantly improves survival of mice bearing tumors harboring the zinc-deficient Trp53 R172H allele but not the Trp53 -/- allele. We synthesized a new formulation of ZMC1 (Zn-1), in which the drug is made in complex with zinc to improve zinc delivery, and demonstrate that Zn-1 has increased efficacy. Furthermore, we show that ZMC1 plus olaparib is a highly effective combination for p53R172H tumor growth inhibition. In conclusion, we have validated preclinically a new therapeutic approach for BRCA1 deficient breast cancer through reactivation of mutant p53.

Adjuvant therapeutic strategies for resectable pancreatic adenocarcinoma

Of all patients diagnosed with pancreatic adenocarcinoma, only 15-20% present with resectable disease. Despite curative-intent resection, the prognosis remains poor with the majority of patients recurring, prompting the need for adjuvant therapy. Historical data support the use of adjuvant 5-fluorouracil (5-FU) or gemcitabine, but recent data suggest either gemcitabine plus capecitabine or modified FOLFIRINOX can improve overall survival when compared to gemcitabine alone. The use of adjuvant chemoradiation therapy remains controversial, primarily due to limitations in study design and mixed results of historical trials. The ongoing Radiation Therapy Oncology Group (RTOG)-0848 trial hopes to further define the role of adjuvant chemoradiation therapy. Intraoperative radiation therapy (IORT) and adjuvant immunotherapy represent additional possibilities to improve outcomes, but evidence supporting their use is limited. This article reviews adjuvant therapeutic strategies for resectable pancreatic adenocarcinoma, including chemotherapy, chemoradiation therapy, IORT and immunotherapy.

Zinc Metallochaperones Reactivate Mutant p53 Using an ON/OFF Switch Mechanism: A New Paradigm in Cancer Therapeutics

Purpose: Zinc metallochaperones (ZMC) are a new class of anticancer drugs that reactivate zinc-deficient mutant p53 by raising and buffering intracellular zinc levels sufficiently to restore zinc binding. In vitro pharmacodynamics of ZMCs indicate that p53-mutant activity is ON by 4-6 hours and is OFF by 24. We sought to understand the mechanism of this regulation and to translate these findings preclinically. We further sought to innovate the formulation of ZMCs to improve efficacy.Experimental Design: We performed in vitro mechanistic studies to determine the role of cellular zinc homeostatic mechanisms in the transient pharmacodynamics of ZMCs. We conducted preclinical pharmacokinetic, pharmacodynamic, and efficacy studies using a genetically engineered murine pancreatic cancer model (KPC) to translate these mechanistic findings and investigate a novel ZMC formulation.Results:In vitro, cellular zinc homeostatic mechanisms that restore zinc to its physiologic levels function as the OFF switch in ZMC pharmacodynamics. In vivo pharmacokinetic studies indicate that ZMCs have a short half-life (< 30 minutes), which is sufficient to significantly improve survival in mice expressing a zinc-deficient allele (p53^R172H) while having no effect in mice expressing a non-zinc-deficient allele (p53^R270H). We synthesized a novel formulation of the drug in complex with zinc and demonstrate this significantly improves survival over ZMC1.Conclusions: Cellular zinc homeostatic mechanisms function as an OFF switch in ZMC pharmacodynamics, indicating that a brief period of p53-mutant reactivation is sufficient for on-target efficacy. ZMCs synthesized in complex with zinc are an improved formulation. Clin Cancer Res; 24(18); 4505-17. ©2018 AACR.

Zinc Metallochaperones as Mutant p53 Reactivators: A New Paradigm in Cancer Therapeutics

Restoration of wild-type structure and function to mutant p53 with a small molecule (hereafter referred to as "reactivating" mutant p53) is one of the holy grails in cancer therapeutics. The majority of TP53 mutations are missense which generate a defective protein that is targetable. We are currently developing a new class of mutant p53 reactivators called zinc metallochaperones (ZMCs) and, here, we review our current understanding of them. The p53 protein requires the binding of a single zinc ion, coordinated by four amino acids in the DNA binding domain, for proper structure and function. Loss of the wild-type structure by impairing zinc binding is a common mechanism of inactivating p53. ZMCs reactivate mutant p53 using a novel two-part mechanism that involves restoring the wild-type structure by reestablishing zinc binding and activating p53 through post-translational modifications induced by cellular reactive oxygen species (ROS). The former causes a wild-type conformation change, the later induces a p53-mediated apoptotic program to kill the cancer cell. ZMCs are small molecule metal ion chelators that bind zinc and other divalent metal ions strong enough to remove zinc from serum albumin, but weak enough to donate it to mutant p53. Recently we have extended our understanding of the mechanism of ZMCs to the role of cells' response to this zinc surge. We found that cellular zinc homeostatic mechanisms, which normally function to maintain free intracellular zinc levels in the picomolar range, are induced by ZMCs. By normalizing zinc levels, they function as an OFF switch to ZMCs because zinc levels are no longer sufficiently high to maintain a wild-type structure. This on/off switch leads to a transient nature to the mechanism of ZMCs in which mutant p53 activity comes on in a few hours and then is turned off. This finding has important implications for the translation of ZMCs to the clinic because it indicates that ZMC concentrations need not be maintained at high levels for their activity. Indeed, we found that short exposures (as little as 15 min) were adequate to observe the mutant p53 reactivating activity. This switch mechanism imparts an advantage over other targeted therapeutics in that efficacy can be accomplished with minimal exposure which minimizes toxicity and maximizes the therapeutic window. This on/off switch mechanism is unique in targeted cancer therapeutics and will impact the design of human clinical trials.

Copper-Binding Small Molecule Induces Oxidative Stress and Cell-Cycle Arrest in Glioblastoma-Patient-Derived Cells

Transition metals are essential, but deregulation of their metabolism causes toxicity. Here, we report that the compound NSC319726 binds copper to induce oxidative stress and arrest glioblastoma-patient-derived cells at picomolar concentrations. Pharmacogenomic analysis suggested that NSC319726 and 65 other structural analogs exhibit lethality through metal binding. Although NSC319726 has been reported to function as a zinc ionophore, we report here that this compound binds to copper to arrest cell growth. We generated and validated pharmacogenomic predictions: copper toxicity was substantially inhibited by hypoxia, through an hypoxia-inducible-factor-1α-dependent pathway; copper-bound NSC319726 induced the generation of reactive oxygen species and depletion of deoxyribosyl purines, resulting in cell-cycle arrest. These results suggest that metal-induced DNA damage may be a consequence of exposure to some xenobiotics, therapeutic agents, as well as other causes of copper dysregulation, and reveal a potent mechanism for targeting glioblastomas.

A novel combined interventional radiologic and hepatobiliary surgical approach to a complex traumatic hilar biliary stricture

INTRODUCTION

Benign strictures of the biliary system are challenging and uncommon conditions requiring a multidisciplinary team for appropriate management.

PRESENTATION OF CASE

The patient is a 32-year-old male that developed a hilar stricture as sequelae of a gunshot wound. Due to the complex nature of the stricture and scarring at the porta hepatis a combined interventional radiologic and surgical approach was carried out to approach the hilum of the right and left hepatic ducts. The location of this stricture was found by ultrasound guidance intraoperatively using a balloon tipped catheter placed under fluoroscopy in the interventional radiology suite prior to surgery. This allowed the surgeons to select the line of parenchymal transection for best visualization of the stricture. A left hepatectomy was performed, the internal stent located and the right hepatic duct opened tangentially to allow a side-to-side Roux-en-Y hepaticojejunostomy (a Puestow-like anastomosis).

DISCUSSION

Injury to the intrahepatic biliary ductal confluence is rarely fatal, however, the associated injuries lead to severe morbidity as seen in this example. Management of these injuries poses a considerable challenge to the surgeon and treating physicians.

CONCLUSION

Here we describe an innovative multi-disciplinary approach to the repair of this rare injury.

Abstract B211: Cellular zinc homeostatic mechanisms function as an off switch for zinc metallochaperone-mediated reactivation of mutant p53

The p53 transcription factor functions as one of cancer’s most potent tumor suppressors and is the most frequently mutated gene in human cancer. The majority of p53 mutations (&gt;70%) are missense that generate a defective protein found at high levels in cells that is targetable. Restoration of wild type structure and function of mutant p53 with a small molecule (so-called reactivation) is a highly sought after goal in anticancer drug development. The p53 protein requires the binding of a single zinc ion to fold properly, and mutations that impair the protein’s ability to bind zinc (and cause it to misfold) are highly prevalent in cancer. We recently discovered a new class of small-molecule zinc chelators named zinc metallochaperones (ZMCs) that reactivate zinc-deficient mutant p53 through a novel mechanism involving both zinc ionophore activity to raise intracellular zinc concentrations and donation to restore zinc binding to mutant p53. This induces a wild type conformation change and a p53-mediated apoptotic program. The lead compound (ZMC1) displays a transient pharmacodynamics (p21 levels) in vitro. We hypothesized that the regulation of these pharmacodynamics is governed by cellular zinc homeostatic mechanisms that function to restore zinc to its physiologic picomolar levels. We examined the entire suite of zinc homeostatic genes in response to ZMC1 and manipulated several metallothionein genes by knockout and knockdown. The net effect of this was to increase the peak and duration of intracellular zinc levels that lead to a more potent and sustained duration of p21 expression. This translated to increased sensitivity to ZMC1. We further postulated that this pharmacodynamics would allow the drug to function with very minimal exposure, and colony formation studies in vitro indicated that a 2-hour exposure was as effective as a 72-hour exposure. We then sought to translate this mechanism in vivo using a genetically engineered murine model of KPC pancreatic cancer (Pdx-1Cre; KrasG12D) that expresses either the p53R172H (zinc deficient) allele or p53R270H (non-zinc deficient). Pharmacokinetic (PK) studies of the drug revealed a short half-life (15 minutes) indicating a minimal exposure. Despite this, daily, intermittent dosing at the maximum tolerated dose resulted in a statistically significant increase in the overall survival of the KPC-p53R172H mice while having no such effect in the KPC-p53R270H. We sought to improve the efficacy of ZMC1 by preloading it with zinc in a 2:1 molar ratio based on the crystal structure. The drug-zinc complex (Zn-1) increased the median survival of KPCp53-R172H mice from 26 days to 35 days (ZMC1 monomer versus Zn-1). These studies indicate that cellular zinc homeostatic mechanisms function as an “off” switch for ZMCs, which has important implications for the translation of ZMCs in humans. Principally, this allows the drug to function with minimal exposure, which minimizes potential zinc toxicity. ZMC1 as monotherapy improves survival in an allele-specific mutant p53 manner. Furthermore, ZMC1 can be optimized by synthesizing it complexed with zinc. Overall, this “off” switch is novel for a targeted molecular therapeutic and represents a significant departure from the traditional paradigm where the goal is to develop a compound that binds the target with a PK profile that provides maximal exposure.

Citation Format: Xin Yu, Samuel Kogan, Ying Chen, Ashley T. Tsang, Tracy Withers, Hongxia Lin, Chunxia Chen, Dirk F. Moore, Joseph Bertino, Chang Chan, Darren R. Carpizo. Cellular zinc homeostatic mechanisms function as an off switch for zinc metallochaperone-mediated reactivation of mutant p53 [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B211.

Conditional survival analysis of stage IV colorectal cancer patients living >24 months

3566

Background: The overall survival of patients with stage IV colorectal cancer (both in unresectable and resectable settings) has been increasing over recent decades due to improvements in chemotherapy, liver surgery and other liver-directed therapies. As a result of more patients living longer, there is a need to refine prognostic information to more accurately predict survival to assist multi-disciplinary cancer management teams in treatment decisions but also for patient quality of life. Methods: We performed a retrospective analysis of all patients with stage IV colorectal cancer seen at Rutgers Cancer Institute of New Jersey between Jan 1, 2005 to March 10, 2015 by ICD-9 code (N = 318 patients). This included patients who were deemed unresectable and patients who were resected with curative intent. Our study population was patients with documented survival for > 24 months (N = 158). Variables gathered included patient demographics, disease related (primary location, KRAS status, metastasis location, interval to metastases) and treatment related (chemotherapy regimens, radiation and surgery) data. Survival curve estimates are conditional on having survived 24 months. Results: Complete data was available for 125 patients (75 were resected for cure and 50 were not). Median overall survival of resected patients was not reached. The median overall survival of non-resected patients was 75.9 months. Univariate and multivariate analysis for surgery and non-surgery groups was performed. No statistically significant covariates were found beyond surgical resectability. The conditional survival probabilities of living 1, 2 or 3 years longer after 24 months of survival are 91.7%, 71.6% and 51.6% respectively in the patients with unresectable disease, and 98.1%, 92.2% and 88.8% in patients who were able to be resected with curative intent. Conclusions: These results indicate that patients who survive 24 months with stage IV colorectal cancer have an excellent prognosis. For patients who are unresectable and survive 24 months, this study suggests that they may benefit from resection of remaining metastatic sites if feasible. For resected patients this information may propose a possible benefit from repeat metastasectomy.

U1 Adaptors Suppress the KRAS-MYC Oncogenic Axis in Human Pancreatic Cancer Xenografts

Targeting KRAS and MYC has been a tremendous challenge in cancer drug development. Genetic studies in mouse models have validated the efficacy of silencing expression of both KRAS and MYC in mutant KRAS-driven tumors. We investigated the therapeutic potential of a new oligonucleotide-mediated gene silencing technology (U1 Adaptor) targeting KRAS and MYC in pancreatic cancer. Nanoparticles in complex with anti-KRAS U1 Adaptors (U1-KRAS) showed remarkable inhibition of KRAS in different human pancreatic cancer cell lines in vitro and in vivo As a nanoparticle-free approach is far easier to develop into a drug, we refined the formulation of U1 Adaptors by conjugating them to tumor-targeting peptides (iRGD and cRGD). Peptides coupled to fluorescently tagged U1 Adaptors showed selective tumor localization in vivo Efficacy experiments in pancreatic cancer xenograft models showed highly potent (>90%) antitumor activity of both iRGD and (cRGD)₂-KRAS Adaptors. U1 Adaptors targeting MYC inhibited pancreatic cancer cell proliferation caused by apoptosis in vitro (40%-70%) and tumor regressions in vivo Comparison of iRGD-conjugated U1 KRAS and U1 MYC Adaptors in vivo revealed a significantly greater degree of cleaved caspase-3 staining and decreased Ki67 staining as compared with controls. There was no significant difference in efficacy between the U1 KRAS and U1 MYC Adaptor groups. Our results validate the value in targeting both KRAS and MYC in pancreatic cancer therapeutics and provide evidence that the U1 Adaptor technology can be successfully translated using a nanoparticle-free delivery system to target two undruggable genes in cancer. Mol Cancer Ther; 16(8); 1445-55. ©2017 AACR.

Thiosemicarbazones Functioning as Zinc Metallochaperones to Reactivate Mutant p53

Small-molecule restoration of wild-type structure and function to mutant p53 (so-called mutant reactivation) is a highly sought-after goal in cancer drug development. We previously discovered that small-molecule zinc chelators called zinc metallochaperones (ZMCs) reactivate mutant p53 by restoring zinc binding to zinc-deficient p53 mutants. The lead compound identified from the NCI-60 human tumor cell lines screen, NSC319726 (ZMC1), belongs to the thiosemicarbazone (TSC) class of metal ion chelators that bind iron, copper, magnesium, zinc, and other transition metals. Here, we have investigated the other TSCs, NSC319725 and NSC328784, identified in the same screen, as well as the more well studied TSC, 3-AP (Triapine), to determine whether they function as ZMCs. We measured the zinc K_d zinc ionophore activity, ability to restore zinc to purified p53 DNA binding domain (DBD), and ability to restore site-specific DNA binding to purified R175H-DBD in vitro. We tested all four TSCs in a number of cell-based assays to examine mutant p53 reactivation and the generation of reactive oxygen species (ROS). We found that NSC319725 and NSC328784 behave similarly to ZMC1 in both biophysical and cell-based assays and are heretofore named ZMC2 (NSC319725) and ZMC3 (NSC328784). 3-AP generates a ROS signal similar to ZMC1-3, but it fails to function as a ZMC both in vitro and in cells and ultimately does not reactivate p53. These findings indicate that not all TSCs function as ZMCs, and much of their activity can be predicted by their affinity for zinc.

Abstract 2097: Translating a mutant p53 reactivating drug (ZMC1) in murine pancreatic cancer models

Pancreatic cancer therapy suffers from a lack of effective chemotherapy. TP53 is second only to KRAS as the most commonly mutated gene in pancreatic cancer with point mutations occurring in 75% of patients. We identified ZMC1 as an allele specific mutant p53 reactivator and lead compound for mutant p53 targeted drug development. ZMC1 restores wildtype structure and function by functioning as a zinc metallochaperone to restore zinc binding to mutant p53 proteins with impaired zinc binding. Our aim was to translate this novel mechanism in vivo using murine pancreatic cancer models. We investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of ZMC1 and performed efficacy studies for allele specificity in nude mice with subcutaneous tumors from murine pancreatic cancer cell lines derived from a genetically engineered mouse model (KPC) expressing mutant KrasG12D and different alleles of TP53 (WT, null, p53R172H, p53R270H). Tumor growth inhibition became apparent only in KPCp53-R172H xenografts but not in KPCp53-R270H. We then performed efficacy studies in the autochthonous KPC model and found that, ZMC1 extended the median survival from 15 to 26 days in the KPCp53-R172H mice (p = 0.05) but not in the KPCp53-R270H mice. We sought to improve the efficacy of ZMC1 by synthesizing it complexed with zinc (Zn-1) in a 2:1 molar ratio. Zn-1 significanlty increased the median survival of KPCp53-R172H mice from 15 to 35 days (p = 0.0042). The apoptosis rate in the tumors (by Immunohistochemistry staining with Cleaved Caspase 3) was also increased by treatment of ZMC1 and Zn-1. These studies indicate that ZMC1 can function in vivo as a mutant p53 targeted anti-cancer drug at doses that are well tolerated. Furthermore, ZMC1 can be optimized by synthesizing it complexed with zinc.

Citation Format: Xin Yu, Ashley T. Tsang, Tracy Withers, John Gelleran, David Augeri, S. David Kimball, Darren R. Carpizo. Translating a mutant p53 reactivating drug (ZMC1) in murine pancreatic cancer models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2097.

Abstract 3833: Restoration of wildtype structure and function of mutant p53 by thiosemicarbozones using a novel zinc metallochaperone based mechanism

NSC319726 (ZMC1) is a small molecule that reactivates mutant p53 by restoration of WT structure and function to the most common p53 missense mutant (p53-R175H). We identified that ZMC1 functions as a zinc-metallochaperone, providing an optimal concentration of zinc to facilitate proper folding of p53 protein, and increasing cellular reactive oxygen species to transactivate the newly conformed p53-R175H (via post-translational modifications). ZMC1 was identified from an in silico screen of the NCI anti-cancer drug screen along with two other thiosemicarbazones (TSCs), NSC319725 and NSC328784. We investigated these TSCs to determine if they could reactivate mutant p53 using a zinc metallochaperone mechanism. We found that indeed these compounds could reactivate mutant p53 by functioning as zinc metallochaperones. In distinction, Triapine the only TSC in clinical development, does not function as a zinc metallochaperone and is not a mutant p53 reactivator.

Citation Format: Xin Yu, Adam R. Blanden, Ashley T. Tsang, Saif Zaman, John Gelleran, David Augeri, S. David Kimball, Stewart N. Loh, Darren R. Carpizo. Restoration of wildtype structure and function of mutant p53 by thiosemicarbozones using a novel zinc metallochaperone based mechanism. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3833.