Cancer Preventive Agents Research Articles

Abstract A016: Successful design and execution of two gastric cancer chemoprevention trials in Central America and Puerto Rico

Abstract Gastric adenocarcinoma (GAC) is the third leading global cause of cancer mortality and leading infection-associated cancer. The high incidence regions are Latin America, East Asia, and Eastern Europe. In the U.S., GAC represents a major cancer disparity, double the incidence rates in all non-white populations, the opposite of Barrett’s Esophagus and EAC. Immigrants from high incidence regions maintain the risk profile of their nations of origin. In a paradigm shift, recent guidelines now recommend surveillance endoscopy (eg, 3 years) for patients with high-risk gastric premalignant conditions (GPMCs). Clinical trials of chemoprevention agents for patients with GPMCs are lacking. We conducted two independent, NCI DCP funded, phase II placebo-controlled chemoprevention trials in patients with GPMCs (intestinal metaplasia, atrophic gastritis). The oral agents were curcumin and eflornithine (DFMO). A highly bioavailable preparation of curcumin was used. The RCTs were conducted in Puerto Rico and rural Honduras, with important characteristics: (1) representative of Caribbean and Mesoamerican populations and linked to large U.S. immigrant populations; (2) high prevalence of H. pylori infection and GPMCs; (3) absence of turmeric and curcuminoids in the local diets; (4) proven bidirectional collaboration with academic institutions in the U.S. In the curcumin trial (NCT02782949) H. pylori negative patients were randomized to study drug or placebo for 6 months. In the eflornithine study (NCT02794428), H. pylori positive and negative subjects were randomized to study drug or placebo for 18 months, with endoscopy at baseline, and 6. 18, and 24 months. The primary outcomes were based upon changes in histologic parameters at 6 months. Principal study challenges included: (1) International and bilingual regulatory environment; (2) Strengthening of the research infrastructure, particularly in Central America; (3) Participant recruitment, eg, in the curcumin RCT in Honduras wherein only 10-15% are H. pylori negative; (4) The Covid-19 pandemic; (5) Natural disasters (3 hurricanes). In Conclusion: Eflornithine and curcumin RCTs have been successfully completed, despite important challenges in implementation and execution. No losses to follow-up were encountered related to the pandemic or natural disasters. The south-south partnership may provide a model for chemoprevention and translational studies in Latino populations with prevalent cancers such as GAC. Citation Format: Eleazar Montalvan-Sanchez, Maria Gonzalez-Pons, Dalton Norwood, Ricardo Dominguez, Keith Wilson, Marcia Cruz-Correa, Douglas Morgan. Successful design and execution of two gastric cancer chemoprevention trials in Central America and Puerto Rico [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A016.

Abstract IA008: How to move a preventative agent from design into approval

Abstract Cancer prevention is a global public health challenge that requires a multidisciplinary approach including biology, epidemiology, medicine, nutrition, education, clinical trials and public policy. An intent-to-treat analysis of a randomized controlled trial differs from that in the observational setting, therefore, it is important to understand the underlying disease process and aspects of the intervention through research. The genetic heterogeneity of some cancers strongly support an enhanced focus on prevention as a strategy in high-risk individuals. Important factors when developing preventative cancer agents include the time course of the intervention, dose and duration of exposure needed to effect risk reduction, trial endpoints, durability of the impact of intervention, and methodological problems in implementing and interpreting randomized trials to evaluate prevention strategies. The clinical development of cancer prevention therapeutics has many challenges, including the long duration necessary to conduct trials, the lack of adherence to therapy, and unanswered questions on the best endpoint remain. The government, whether it be local, state or national, plays a vital role in regulation and education. The history of chemoprevention regulatory approvals has taught us that these programs are important in the fight against cancer. The Food and Drug Administration has identified barriers to clinical trial participation and challenges in surrogate endpoints, although with a multidisciplinary approach including communication with industry, are extremely positive about the future direction of chemoprevention research. Citation Format: Danielle Krol. How to move a preventative agent from design into approval [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA008.

Abstract A003: Identification of a potential chemoprevention agent for BRCA1- mutated cancers

Abstract BRCA1 mutation carriers are predisposed to developing aggressive breast, ovarian, and other cancers at a relatively early age. Unfortunately, these cancers lack an effective chemoprevention option. We have found that cells containing mutant BRCA1 harbor defective repair of oxidative DNA damage, an early trigger to tumorigenesis. Therefore, we sought to target this defect and discover a novel chemoprevention agent for these cancers. High-throughput screening of a chemical library identified a novel class of small-molecules that enhance repair of oxidative DNA damage, which we termed DNA repair-activating agents. One of these agents, benserazide, increased base-excision repair of oxidative DNA damage utilizing a cell-based DNA repair assay, decreased levels of 8-oxo-g (i.e. most common oxidized lesion in human genome) using flow cytometric analysis, and decreased levels of oxidative DNA damage as determined by alkaline comet assay modified for detection of oxidized DNA lesions. These results were observed in mutant but not wild-type BRCA1 breast cancer cells. Benserazide, but not tamoxifen (current FDA-approved breast cancer chemoprevention agent), also decreased in vitro tumorigenesis of mutant BRCA1 or BRCA1-depleted breast cancer cells according to the soft-agar colony formation assay, and delayed tumor formation in vivo using a xenograft mouse model. Lastly, benserazide led to elevated levels of 8-oxo-dG (a by-product of base-excision repair) in conditioned media of mutant BRCA1 breast cancer cells, and concurrently increased serum levels of 8oxodG and decreased tumor burden in mice. Taken together, benserazide is a DNA-repair activating agent that enhances repair of oxidative DNA damage and decreases tumorigenesis in vitro and in vivo, and thus may serve as a potential chemoprevention agent for BRCA1-mutated cancers. Further, circulating levels of 8oxoG/8oxodG may function as a predictive biomarker for the efficacy of benserazide, which would prove useful in the clinical evaluation of benserazide for cancer chemoprevention. Citation Format: Sujeeth Shanmugam, Eboni Hosch, Dipasri Konar, James M. Ford, Elizabeth Alli. Identification of a potential chemoprevention agent for BRCA1- mutated cancers [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A003.

Abstract IA019: Clinical trials of GUCY2C (GCC) agonists for colorectal cancer prevention

Abstract Guanylyl cyclase C (GUCY2C), expressed on intestinal epithelial cells, is the receptor for heat-stable enterotoxins (STs) produced by diarrheagenic bacteria. Fluid secretion reflects ST activation of GUCY2C, which produces cyclic (c)GMP activating ion channels. Beyond toxins, GUCY2C binds uroguanylin in small intestine and guanylin in colorectum, which also stimulate secretion. This mechanism is the basis for the oral agonists linaclotide (ST analog) and plecanatide (uroguanylin analog) to treat constipation. Guanylin is the most commonly lost gene product, while GUCY2C expression is retained, in colorectal tumors. Eliminating GUCY2C promotes tumor formation, while oral GUCY2C agonists or transgenic guanylin reduce intestinal tumors, in mice. These data support a hypothesis in which loss of guanylin silencing GUCY2C is a key step in intestinal transformation which can be prevented by oral GUCY2C agonists. However, GUCY2C agonists are formulated for duodenal activity, without bioavailability in the colorectum. Here, we explored whether this pharmacokinetic (PK) barrier could be abrogated with high doses (HD) of linaclotide. Indeed, HD linaclotide induced a cGMP response in mucosal biopsies obtained by colonoscopy following oral polyethylene glycol (PEG) preparation. This cGMP response was validated by VASP phosphorylation and suppression of crypt proliferation. Similarly, HD linaclotide induced cGMP in colon biopsies obtained by sigmoidoscopy following oral PEG. However, HD linaclotide failed to induce cGMP in colon biopsies obtained by sigmoidoscopy i n the absence of oral PEG . Thus, oral PEG abrogated the PK barrier, delivering linaclotide to the colorectum. Unfortunately, dolcanatide, a proteolysis-resistant analog of plecanatide, also failed to overcome the colorectal PK barrier, although it produced duodenal secretion and diarrhea. Thus, guanylin loss silencing GUCY2C appears to be a key step in intestinal transformation. Preclinical models suggest that oral GUCY2C agonists stimulate GUCY2C signaling, opposing tumorigenesis. However, translation of these observations appears to be constrained by a PK barrier, reflecting agonists formulated for duodenal activity, without colorectal bioavailability. Exploiting GUCY2C for chemoprevention awaits agonists formulated for the colorectum. We are exploring the ability of GUCY2C agonists to activate cGMP in duodenum (within the PK barrier), as a prelude to trials in patients with FAP at risk for duodenal tumors. Citation Format: Scott A. Waldman. Clinical trials of GUCY2C (GCC) agonists for colorectal cancer prevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA019.

Abstract IA004: Targeting STAT3 with TTI-101, an oral small molecule, to prevent colorectal and hepatocellular cancer

Abstract Persistent STAT3 activation contributes to 10 of 14 hallmarks of cancer, including inflammation; successful targeting of STAT3 has the potential to prevent and/or treat cancer. However, no small molecule that directly targets STAT3 has been FDA approved. The Tweardy lab used computer-based docking of drug-like compounds into the SH2 domain of STAT3, along with hit-to-lead optimization and medicinal chemistry, to identify TTI-101; TTI-101 treatment was safe, hit its target in tumor cells, and resulted in clinical benefit in a Phase I trial of patients with advanced solid tumors. The incidence of colorectal cancer (CRC) is increased 20-30 fold in patients with inflammatory bowel disease (IBD), while 90% of hepatocellular carcinomas (HCC) arise in the setting of chronic inflammation. To assess the contribution of STAT3 to CRC secondary to IBD and to HCC, we performed immunohistochemistry (IHC) staining and computer-based scoring for activated STAT3 (phosphorylated on Y705, pY-STAT3) of epithelial and stromal cells within colonic endoscopic biopsies and surgically resected CRC from IBD patients, as well as of tumor cells and hepatocytes within surgically resected HCC tumors. Compared to epithelium of normal tissue, levels of pY-STAT3 were increased 1.9-fold in dysplastic epithelium (p=0.05) and 1.8-fold in the stroma of normal tissue (p<0.0001). In surgically resected HCC tumors, lower pY-STAT3 scores in tumor cells, but not hepatocytes, correlated with longer recurrence free survival (RFS; p=0.003). TTI-101 administration in three AOM-DSS mouse models of IBD resulted in a dose-dependent reduction in polyps, adenomas, and/or adenocarcinomas. TTI-101 administration to the HepPten- mouse model of NASH-induced HCC resulted in a dose-dependent reduction in liver pY-STAT3 levels. Thus, STAT3 may be a valid target for chemoprevention using TTI-101 in CRC arising from IBD and in HCC. We thank Tvardi Therapeutics for providing TTI-101 for these studies. Citation Format: Prema Robinson, Leticia Hamana, Laura Beretta, Moses Kasembeli, Uddalak Bharadwaj, Yun Shin Chun, Yinghong Wang, Xeumei Wang, Laura Reyes, Luisa Solis, Asif Rashid, Dipen Maru, Eduardo Vila, Apostolia Tsimberidou, Ahmed Kaseb, Scott Kopetz, David Tweardy. Targeting STAT3 with TTI-101, an oral small molecule, to prevent colorectal and hepatocellular cancer [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA004.

Abstract IA020: Targeting mTOR signaling in oral premalignant lesions: From bench to clinic and back

Abstract Despite encouraging recent results from novel treatment options, such as immunotherapy, for head and neck squamous cell carcinoma (HNSCC), limited progress has been made in improving outcomes for most patients. Prevention and early detection are key to improving the prognosis of HNSCC. Our team has focused on decoding the oncogenic signaling circuitries driving HNSCC initiation and progression, aimed at identifying novel druggable targets to treat and prevent this aggressive malignancy. These efforts led to the early discovery that persistent activation of PI3K/mTOR signaling circuitry is the most frequent dysregulated signaling mechanism in HNSCC, and that in turn, the overreliance on PI3K/mTOR for HNSCC initiation and progression can be exploited for therapeutic purposes. Evidence will presented that mTOR inhibition exerts a potent antitumor activity in HNSCC patients in a recently reported window of opportunity clinical trial (NCT01195922). Thus, mTOR inhibitors can be considered for the prevention of HNSCC development and for the treatment of existing HNSCC lesions. However, their safety profile and tolerability may hamper their potential long-term use for HNSCC prevention. In this regard, we have shown that the repurposed drug metformin, which is safely used by millions of type 2 diabetes patients, decreases mTOR signaling in HNSCC and displays potent chemopreventive activity in experimental oral premalignancy models. Based on these findings, we have conducted a Phase IIa Clinical Trial using metformin for HNSCC prevention (NCT02581137) in patients with oral premalignant lesions (OPL), which was recently completed. Metformin administration resulted in mTOR inhibition, and improvement in the histological severity of 60% of the OPLs, including a subset (17%) of patients that exhibited complete responses. Ongoing experimental and planned clinical studies will be presented, which may provide a mechanistic framework for the use of metformin as a precision preventive agent for HNSCC. Citation Format: J. Silvio Gutkind. Targeting mTOR signaling in oral premalignant lesions: From bench to clinic and back [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA020.

Abstract IA016: Lessons learned from clinical trials of MUC1 peptide vaccines for cancer prevention

Abstract We report on three trials of a MUC1 peptide vaccine for cancer prevention. Two trials were pilot studies evaluating vaccine immunogenicity and safety. One was in subjects with advanced colon adenomas, and the other in smokers at risk for lung cancer. The third trial was a multi-center, randomized placebo-controlled trial in subjects with advanced adenoma that included an assessment of the clinical efficacy of the vaccine to prevent recurrent adenoma. All trials successfully recruited their full complement of participants and the vaccine was well tolerated with no safety concerns. The response rate in the colon adenoma trials was 43% in the pilot study and 25% in the placebo- controlled multicenter trial. Only 10% of smokers responded to the vaccine. Higher levels of circulating myeloid derived suppressor cells (MDSC) were consistently associated with the lack of an immune response. This suggests that even in pre-malignancy immunosuppressive tendencies can impair vaccine immunogenicity. Responders to the vaccine demonstrated immune memory at one year. In the multicenter adenoma trial that evaluated the efficacy of the vaccine on adenoma recurrence, immune responders demonstrated an association with a reduced rate of adenoma recurrence. In future studies, patient selection based on circulating MDSC levels, or concomitant use of agents to counter MDSC immunosuppressive function or otherwise improve T cell function, should be considered. Citation Format: Robert E. Schoen. Lessons learned from clinical trials of MUC1 peptide vaccines for cancer prevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA016.

Abstract A022: Limonene as a vehicle in topical delivery of carvedilol for skin cancer chemoprevention

Abstract Skin cancer is currently one of the most common cancers and is defined as an abnormal growth of the skin cells. The goal of this study is to develop a topical delivery system of carvedilol with limonene as the vehicle. Limonene is a major component found in the rinds of citrus fruits and other herbs. It is one of many natural compounds that have demonstrated inhibitory activity in different types of cancers such as breast, lung, and stomach cancer. Furthermore, limonene has shown to increase skin permeation of drugs including carvedilol. The soft agar colony formation assay was used to evaluate anchorage-independent growth of JB6 mouse epidermal cells. This assay tested concentrations of carvedilol (0.1, 1.0 and 10 μM); limonene (1.0, 10, 100 and 1000 μM); and a combination of carvedilol (1.0 μM) and limonene (1.0, 10 or 100 μM). Results demonstrated that carvedilol and limonene as single treatment inhibited colony formation. The combination of carvedilol and limonene showed higher colony inhibition than single treatment, although not statistically significant. Franz diffusion cell was used to test for permeation of the drug. The device has two chambers separated by a membrane, which in this case is rat skin. The drugs, in vehicles of 40% polyethylene glycol (PEG) 400 in PBS or 40% PEG400 in PBS plus 5% limonene were applied into the donor chamber while the samples are collected through the receptor chamber as the drug permeates through the skin. The samples were collected at 16 hours, 20 hours, and 24 hours. Results showed that limonene significantly increased permeation. Therefore, our data indicate that limonene was able to increase skin permeation and the chemopreventive activity of carvedilol. This new formulation will be further examined in animal models for its efficacy against UV-induced skin cancer. Citation Format: Janell Wang, Lawrence Chao, Steven Yeung, Ying Huang. Limonene as a vehicle in topical delivery of carvedilol for skin cancer chemoprevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A022.

Abstract A012: Repurposing of the macrolide antibiotic clarithromycin for the prevention of lung cancer

Abstract Lung adenocarcinoma (LUAD), particularly K-ras mutant LUAD, is a leading cause of cancer mortality. Therefore, strategies to prevent K-ras-mutant LUAD in its earliest stages in high-risk individuals (e.g., smokers) are urgently needed to reduce the public burden of this fatal disease. We and others have shown that K-ras driven tumorigenesis in lung is intimately linked to chronic inflammation and ultimately, tumor cells immune-escape. The antibiotic clarithromycin (CAM) was identified as one of the most promising candidates for repurposing with demonstrated immunomodulatory and anticancer properties. CAM is widely used and belongs to the macrolide class of antibiotics which are among the safest broad spectrum antimicrobials available. Abundant preclinical and clinical evidence exists demonstrating the in vitro and in vivo anticancer effects of CAM. It has been shown that macrolide antibiotics exert suppression of inflammation without overt immunosuppressive effects mostly through the inhibition of proinflammatory cytokines in vitro and in vivo. In these studies, we tested the lung cancer prevention efficacy of CAM using a Kras mutant lung cancer model. In the CCSPCre; LSL-Kras- G12 D (CC-LR) model, activation of the KrasG12 D mutation takes place in club cells by means of removal of the lox-stop-lox genomic sequence via expression of Cre recombinase under the control of the CCSP promoter. This model is excellent for reproducing the various premalignant to malignant progression steps in the lung. CC-LR mice of both genders were randomly enrolled to four experimental arms comparing three CAM doses: 10mg/kg/day, 50mg/kg/day, and 100mg/kg/day, to vehicle control (H2O). Treatment was administered by oral gavage, 5 times per week for 10 wks., starting at 4 wks. of age. At 14 wks. of age mice were euthanized, lung surface tumors were counted, bronchial lavage fluid, as well as lung samples, were obtained for histological, immunohistochemical (IHC) and qRT-PCR analyses. Clarithromycin treatment led to significant lung cancer prevention efficacy, as determined by lung surface tumor counts. A clear dose response with CAM was observed with a mean lung surface tumor count of 30.2 tumors per mouse for vehicle (n=12 mice), 23.5 for CAM 10mg/kg (n=8), 18.8 for CAM 50mg/kg (n=8) and 13.5 tumors per mouse for the CAM 100mg/kg treatment group (n=12, p=0.0014). A significant decrease in the incidence and multiplicity of premalignant and malignant lesions was also observed in histological analyses. For profiling of the lung immune microenvironment, we analyzed by qRT-PCR the expression of 18 genes identifying various cytokines, cell surface markers and proteins characteristic of specific activation states on the various cell subtypes in the tumor microenvironment. We found significant reduction in the expression of pro-inflammatory cytokines, IL-6, TNF, and IL-1β that are known to have a pro-tumor function in lung tumorigenesis, shown previously by us and other groups. We also found a reduction in the expression of myeloid cell-specific immunosuppressive markers, Arg1 and Fizz 1, that could be due to the reduction in the Gr1+ myeloid cell population, which was detected by means of IHC analyses on the same samples, or due to reprograming of pro-tumor M2 type macrophages toward an anti-tumor M1 phenotype. We also see a trend toward reduction of IL-17 cytokine, which we have previously shown to have an essential role in the promotion of K-ras mutant lung tumors. This was associated with an increase, although not significant, in the expression of anti-tumor Th1-specific transcription factor. However, we see an increase in the expression of PD-1, which could be due to the potential induction of an exhausted T cell phenotype. Taken together, we see a reprograming of the lung microenvironment from a tumor-promoting immunosuppressive phenotype toward an anti-tumor phenotype. This work was supported by NCI PREVENT TORFP75N91019F00131 (TORFP 2019 E-05). Citation Format: Seyed Javad Moghaddam, Tabish Hussain, Melody Zarghooni, Walter V. Velasco, Linda Phan, Michelle I. Savage, Jennifer T. Fox, Shizuko Sei, Powel H. Brown, C. Marcelo Aldaz. Repurposing of the macrolide antibiotic clarithromycin for the prevention of lung cancer [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A012.

Abstract A009: Effects of commonly prescribed β-blockers on tobacco carcinogen induced reactive oxygen species in human non-tumorigenic lung epithelial cells

Abstract Lung cancer is a detrimental disease to humans and tobacco smoking causes more than 80% of lung cancer deaths. Chemoprevention is currently the major strategy to prevent smoking related lung cancer deaths. Key components that contribute to tobacco carcinogenicity are benzo(a)pyrene [B(a)P] and its diol epoxide metabolite BPDE. The goal of this study is to evaluate the level of reactive oxygen species (ROS), a mediator for cellular DNA damage leading to cancer, when pre-treated with the β-blockers carvedilol and nebivolol, and the antioxidant resveratrol. B(a)P and BPDE were used to induce ROS in human lung epithelial cells (BEAS-2B). The non- fluorescent and non-polar 2’,7- dichlorofluorescein diacetate (DCFH-DA) probe was added to the cells. DCFH-DA was converted to DCFH in the cells by hydrolyzation of DCFH. ROS then induced the conversation of DCFH into 2,7-dichlorofluorescein (DCF). Florescence of DCF was measured by flow cytometry to detect ROS level. B(a)P at concentrations 10 and 100 μM failed to induce ROS while BPDE successfully induced ROS dose-dependently during our pilot study. As a result, different concentrations of BPDE(2 μM and 4 μM) were used to induce ROS. When BEAS-2B was pre-treated with resveratrol (50 μM), ROS was reduced by 42% compared to the cells treated with 2 μM BPDE alone. Additionally, there was a decrease in ROS when pre-treated with nebivolol and carvedilol (5 μM). Nebivolol reduced 52% and 64% of the ROS induced by BPDE 2 μM and 4 μM, respectively. Carvedilol reduced 31% and 10% of the ROS induced by BPDE 2 μM and 4 μM, respectively. These results suggest that some commonly used anti-hypertensive agents, such as the β-blockers , may block or reduce tobacco carcinogen induced ROS and thus can be used as chemopreventive agents for lung cancer. Citation Format: Jenny Lee, Ayaz Shahid, Ying Huang. Effects of commonly prescribed β-blockers on tobacco carcinogen induced reactive oxygen species in human non-tumorigenic lung epithelial cells [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A009.

Abstract IA001: Intercepting pancreatic cancer development with oncogene targeted immunotherapy

Abstract Pancreatic adenocarcinoma (PDAC) progression is triggered by a complex interaction of genetic mutations, stromal cell interactions and tumor microenvironmental (TME) signals. Diagnosis usually occurs late in disease progression, making treatment challenging and survival rates extremely poor. PDACs are also considered non-immunogenic, therefore newly emerging immunotherapies that have been successful in other cancers have not significantly progressed PDAC treatment options. Resistance to immunotherapies progresses as normal cells undergo the earliest genetic changes that transform them into early pre-malignant lesions. The two most common premalignant lesions are pancreatic intra-epithelial neoplasms (PanINs) and intraductal papillary mucinous neoplasm (IPMN). Both types of premalignant lesions eventually accumulate additional genetic changes that lead to early-stage invasive cancer and eventually, to late stage PDAC. This transformation process is influenced by both tumor-intrinsic and extrinsic forces within the developing TME. Accumulating data suggests that immune resistance mechanisms also evolve with this progression, which has led to the hypothesis that early immune intervention may be the best time to intervene to slow or even halt disease progression and improve treatment outcomes. We know that tumor initiation to metastases takes years to decades, providing a unique window of opportunity for the prevention of premalignant progression. KRAS mutations are an early oncogenic event present in over 90% of PanINs and 75% of IPMNs. Initial studies examining cancer vaccines targeted to early oncogenic mutations are showing promise in animal models. A listeria-based vaccine engineered to express oncogenic KrasG12D combined with and without regulatory T cell depletion by an anti-CD25 antibody (PC61) and cyclophosphamide showed increased T cell infiltration, decreased disease progression, and increased survival in Kras-driven and p53 mutated genetically engineered mice (KrasG12D/+Trp53R172H/+;Pdx-1-Cre (KPC) mice) with early PanIN lesions but not those with later stage PanINs (Keenan et. al. 2014. Gastroenterology 146: 1784). Other early oncogenic mutations in PDACs may prove to be therapeutic targets for vaccine development. We recently initiated a pilot study to examine the feasibility and safety of targeting mKRAS in patients with resected PDAC. For this, we developed a clinical–grade pooled peptide vaccine targeting 6 common KRAS mutations. This vaccine has been tested in combination with checkpoint blockade in 10 PDAC patients who had undergone surgery plus peri–operative chemotherapy and had remained disease–free (NCT04117087). Longitudinal immune phenotyping showed a robust peripheral mKRAS–specific T cell response against the most vaccinated epitopes. Flow cytometry revealed that these CD4 and CD8 T cells were activated, polyfunctional and displayed a memory phenotype. Based on the favorable immunogenicity and safety profile of our peptide vaccine in patients with resected PDAC, we have initiated a Prevention Study testing our mKRAS vaccine in individuals at high risk for PDAC. This study is currently enrolling and early results will be described. Citation Format: Elizabeth M. Jaffee. Intercepting pancreatic cancer development with oncogene targeted immunotherapy [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA001.

Abstract IA012: Sulindac modulates the response of proficient MMR colorectal cancer to immune checkpoint inhibitors

Abstract Immune checkpoint inhibitors (ICIs) therapy has been widely used to treat different human cancers, particularly advanced solid tumors. However, clinical studies have reported that ICI immunotherapy benefits only ~15% of colorectal cancer (CRC) patients, specifically those with tumors characterized by microsatellite instability (MSI), a molecular marker of defective DNA mismatch repair (dMMR). For the majority of CRC patients who carry proficient MMR (pMMR), ICIs have shown little clinical benefit. In this study, we examined the efficacy of sulindac to enhance the response of pMMR CRC to anti-PD-L1 immunotherapy. We first utilized CT26 and CMT93 syngeneic mouse tumor models to compare the inhibitory effects of PD-L1 antibody (Ab), sulindac, and their combination on pMMR CRC tumor growth. We found that mice treated with combination therapy showed a significant reduction in tumor volume, along with increased infiltration of CD8+ T lymphocytes in the tumor tissues. We also demonstrated that sulindac could downregulate PD-L1 by blocking NF-κB signaling, which in turn led to a decrease in exosomal PD-L1. Notably, PD-L1 Ab can be bound and consumed by exosomal PD-L1 in the blood circulation. Therefore, in combination therapy, sulindac downregulating PD-L1 leads to increased availability of PD-L1 Ab, which potentially improves the overall efficacy of anti-PD-L1 therapy. We validated all these results using humanized Patient-Derived Xenografts (PDX) animal models. Moreover, we demonstrated the safety of low-dose sulindac as it did not have a systemic inhibitory effect on prostaglandin E2 (PGE2). In conclusion, our findings provide unique insights into the mechanism of action and efficacy for sulindac as an immunomodulatory agent for the ICI therapy and immunoprevention of pMMR CRC. Citation Format: Yaguang Xi. Sulindac modulates the response of proficient MMR colorectal cancer to immune checkpoint inhibitors [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA012.

Abstract IA014: Mass spectrometry and RNAseq based discovery of frameshift neoantigens and cryptic neoantigens from malignant peripheral nerve sheath tumors for prophylactic vaccines

Abstract Neurofibromatosis type 1 (NF1) syndrome is an autosomal, dominant tumor predisposition syndrome caused by loss-of-function mutations of NF1 gene encoding neurofibromin. Loss of the non-mutant allele of NF1 in a rare Schwann cell or precursor leads to benign plexiform neurofibromas. The main cause of death among NF1 patients is the malignant peripheral nerve sheath tumor (MPNST), a highly aggressive soft tissue sarcoma that most likely develops from plexiform neurofibroma, in particular the so-called “atypical” plexiform neurofibroma. Approximately half of MPNSTs are NF1-associated, and NF1 patients have ~15% lifetime risk of developing this terrible cancer. NF1 patients could greatly benefit from prophylactic vaccination that would prevent the malignant transformation to MPNSTs. We hypothesize that malignant transformation leads to the expression of recurrent alternately processed transcripts, such as transcriptionally-induced chimeras, that could express neoantigens and be used as targets for prophylactic vaccines. Such transcripts can be translated to produce novel peptides downstream of frameshift mutations caused by coding exon read-through into introns, mis-splicing from a coding exon to a non-canonical splice acceptors or splice acceptors in other genes. In most cases, a premature termination codon (PTC) will be rapidly encountered by the ribosome translating such transcripts. Therefore, we furthermore hypothesize that these alternately processed transcripts can express what we call “cryptic” neoantigens when treated with drugs that suppress utilization of premature codons such as Ataluren or gentamicin. In such a way, we could administer a prophylactic vaccine and induce conditionally active immune response that would eliminate nascent tumors only when drug treatment is used. We have developed a PTC suppression read-through reporter which results in presentation of the SIINFEKL peptide on C57BL6/J tumor cells. We developed a bioinformatic algorithm that takes deep RNA-seq data and identifies candidate neoepitopes encoded by non-normally processed or mutant mRNAs called Identifying and Verifying Immunogenic Neoepitopes and Neojunctions (IVINN). We have also achieved successful purification of human HLA Class I complex using an anti-pan HLA antibody column, and bound peptides have been isolated and identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). We plan to utilize these approaches for mouse model and human MPNST patient derived xenografts. Citation Format: David A. Largaespada. Mass spectrometry and RNAseq based discovery of frameshift neoantigens and cryptic neoantigens from malignant peripheral nerve sheath tumors for prophylactic vaccines [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA014.

Abstract IA006: Reverse-engineering discovery of targets, involved cell types, and compounds for liver cancer chemoprevention

Abstract Hepatocellular carcinoma (HCC) is a cancer type with clinically unequivocal and well-defined predisposing conditions, namely chronic fibrotic liver diseases caused by viral hepatitis and metabolic disorders. By following up the at-risk patient cohort, natural history of HCC development can be captured over the timeframe of one to two decades. Archived biospecimens are often available from the time of initial liver disease diagnosis, and unbiased molecular profiling of the specimens provides unique opportunities to interrogate molecular dysregulations confidently correlated with the real long-term clinical outcome, i.e., HCC development from early-stage liver diseases. This “reverse-engineering” strategy helps increase the likelihood of identifying clinically relevant therapeutic targets without solely relying on data from experimental preclinical models. This is particularly useful in cancer chemoprevention target discovery given the the requirement of overwhelmingly lengthy and costly clinical validation of experimentally derived candidate targets, which is often practically infeasible. Utilizing this strategy, we could successfully identify HCC chemoprevention targets (e.g., cellular signaling such as EGFR pathway, circulating bioactive lipids), involved cell types (e.g., hepatic myofibroblasts, conventional dendritic cells), and compounds (e.g., small molecular signaling pathway inhibitors, generic agents), streamline the process of their clinical validation, and facilitate translation of promising chemoprevention agents to the care of liver disease patients. Citation Format: Yujin Hoshida. Reverse-engineering discovery of targets, involved cell types, and compounds for liver cancer chemoprevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA006.

Abstract IA005: Discovery and development of LFA-9 for CRC prevention

Abstract Colorectal Cancer (CRC) is a major public health issue with an estimated 980,000 deaths annually, worldwide. Current trends show an increase of CRC incidence and mortality worldwide. Colonic adenomas are very common in ages 50 and over. Though, nonsteroidal antiinflammatory agents like Aspirin, Naproxen and COX-2 inhibitor and Celecoxib are useful to prevent the polyp progression and reducing CRC burden, continuous/chronic usage of these drugs are limited by GI toxicity and unwanted side effects. Thus, the rationale to establish safer anti-inflammatory agents for CRC prevention is important. Mechanistic studies suggest that up-regulation of 15-PGDH, sparing COX-1/2 and prostaglandin (PG)I2 synthase and/or selectively targeting mPGES-1 and 5-LOX would reduce the cardiovascular side effects and may improve the chemopreventive efficacy. There are limited to no studies on targeting mPGES-1/5LOX and it is one of the unexplored areas in colorectal cancer chemoprevention towards safer drug development. To design and develop selective inhibitors of dual mPGES-1/5-LOX, we used in-silico small molecular docking simulation approaches, and identified LFA-9 as a novel duel mPGES-1/5-LOX inhibitor among >35 analogs. Azoxymethane (AOM)-induced rat colonic tumors were utilized as ex-vivo to assess pharmacodynamic inhibitory effects of LFA-9 on mPGES-1 and 5-LOX by Radio-HPLC. In a series of animal experiments, we established the dose-range of toxicity and optimal doses of LFA-9. Potential preventive efficacy of LFA-9 was assessed AOM-rat colon carcinogenesis (Aberrant Crypt Foci, (ACF) as surrogate marker in male F344 rats and intestinal tumor inhibition in APCMin/+ mice. Furthermore, we have shown the efficacy of LFA-9 administered in the diet at the adenoma stage significantly suppressed colonic adenocarcinoma formation in AOM-induced colon cancer (sporadic CRC model) and PIRC rat model (FAP model). Overall, the above results show that LFA-9, a novel dual mPGES-1/5-LOX inhibitor, is a safer agent and has potential for prevention of CRC in high-risk patients. {This work was supported by NCI-PREVENT Cancer Program, R01 CA213987 and VA Merit Awards} Citation Format: Chinthalapally V. Rao. Discovery and development of LFA-9 for CRC prevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA005.

Abstract A019: Targeting STAT3 for lung cancer prevention

Abstract Former smokers have an elevated risk of lung cancer and account for a large proportion of newly diagnosed lung cancer. Former smokers with airway dysplasia have received modest benefit in randomized chemoprevention trials, while active smokers have not. More effective chemoprevention agents for former smokers at risk for lung cancer are needed. We previously reported that a cyclic double-stranded DNA oligonucleotide STAT3 decoy (CS3D) administered intravenously (IV) had strong anti-tumor effects in lung cancer xenograft models and was also effective as a chemoprevention agent using a tobacco carcinogen (NNK)-induced lung cancer mouse model that mimics “ex-smokers”. CS3D prevents the binding of activated STAT3 dimers to the promoter of target genes and induces p-STAT3 degradation. Our goal was to develop a clinically applicable direct delivery method of CS3D to the lungs. Using fluorescently tagged CS3D, we evaluated the feasibility and determined the optimal dosing schedule of CS3D administered intratracheally (IT, a mimic of human inhalation) compared to IV in mice. IT delivery 3 times/week provided a high initial drug level that was cleared from the lungs within a few hours, while IV dosing provided lower initial drug levels but persisted up to 8 hrs, with CS3D accumulation over time in the lungs. While the pharmacodynamic effect was also greater with systemic dosing, IT delivery produced inhibition of the STAT3 pathway. Phosphorylated STAT3, VEGF, IL6 and Ki67 expression in NNK-induced lung preneoplasias was down-modulated by IT CS3D delivery after 4 weeks of treatment compared to the mutant oligonucleotide (CS3M), confirming our previous findings with IV delivery. We also demonstrated that CS3D delivered IT altered the pulmonary environment by promoting a pro-inflammatory, anti-tumor response in myeloid cells of the lung directly, or by acting on tumor and stromal components to establish an immune-reactive tumor-microenvironment. No toxicities were found during IT or IV treatment and no organ abnormalities were detected by either regimen. A long-term chemoprevention study of CS3D delivered IT in the ex-smoker lung cancer murine model is underway. Our findings suggest that blocking STAT3 may be a useful strategy for lung cancer prevention, and may involve both inhibition of oncogenic signaling and enhanced anti-tumor immunity. Citation Format: Jill M. Siegfried, Adam C. Soloff, Autumn Gaither Davis, Amy A. Powers, Seth H. Eisenberg, Laura P. Stabile. Targeting STAT3 for lung cancer prevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A019.

Abstract A021: Development of a novel MEK inhibitor, NFX-179, as a chemoprevention agent for squamous cell carcinoma

Abstract Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer comprising at least 20% of all non-melanoma skin cancers. While cSCC contributes to significant morbidity and mortality in high-risk individuals, deployment of otherwise effective chemoprevention of cSCC is limited by toxicities. To help address this, we conducted a systematic computational drug repositioning screen which predicted that selumetinib, an FDA-approved MEK inhibitor (MEKi), would reverse transcriptional signatures associated with cSCC development. This is consistent with our genomic analysis implicating ETS2, a transcription factor in the canonical RAS/RAF/MEK/ERK Mitogen-Activated Protein Kinase (MAPK) pathway, as an upstream regulator of cSCC development. Therefore, as a key regulator of the MAPK pathway, we reasoned MEK would be a viable chemopreventive target. Although systemic MEK inhibition suppresses the formation of cSCC in mice, systemic MEKi administration causes significant adverse effects, including diarrhea, peripheral edema, cardiomyopathy and retinal toxicity. Here, we report the development of a topically formulated, metabolically labile, novel MEKi, NFX-179, designed to potently and selectively suppress the MAPK pathway in the skin prior to rapid metabolism in the systemic circulation. NFX-179 was identified from a targeted drug discovery effort based on its biochemical and cellular potency, selectivity, and rapid metabolism upon systemic absorption. In our UV-induced cSCC mouse model, topical application of NFX- 179 gel reduced the formation of new cSCCs by an average of 60% at doses of 0.1% and greater at 28 days. No systemic or skin toxicities were observed in this model. Furthermore, we conducted a second split-mouse randomized controlled study in which NFX-179 0.5% gel was applied to one half of the back and vehicle was applied to the opposite half of each of the UV-irradiated mice. Near complete suppression of cSCC was observed only in the drug-treated area, demonstrating the targeted and dermal effect of the intervention. NFX-179 inhibits the growth of human SCC cell lines in a dose-dependent manner and topical NFX-179 application penetrates human skin and inhibits MAPK signaling in human cSCC explants. Together our data provide compelling rationale for using topical MEK inhibition through application of NFX-179 gel as an effective strategy for cSCC chemoprevention. Citation Format: Kavita Y. Sarin, John Kincaid, Brittney Sell, Jahanbanoo Shahryari, Matthew A. J. Duncton, Elaine Morefield, Wenchao Sun, Omar Chavez-Chiang, Scott R. Plotkin, Gerd G. Kochendoerfer, Peter Fenn, Christopher Powala, Kenneth Y. Tsai. Development of a novel MEK inhibitor, NFX-179, as a chemoprevention agent for squamous cell carcinoma [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A021.

Abstract A007: Assessing immunoprevention efficacy of an agonist of CD137 pathway in a tobacco carcinogen-induced lung cancer preclinical model

Abstract Purpose: Lung cancer is the leading cause of cancer-related deaths worldwide. Cigarette smoking is the primary risk factor for lung cancer and is linked to 80-90% of lung cancer deaths according to the Centers for Disease Control (CDC). The most carcinogenic component of tobacco smoke is NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone). SA-4-1BBL is a novel CD137 receptor agonist that has shown cancer immunoprevention efficacy in transplantable preclinical tumor models by invoking an innate immune surveillance mechanism involving CD4+ CD44+ T and NK cells. As a preclinical model for high-risk populations, we evaluated the immunoprevention efficacy of SA-4-1BBL in lung tumor formation induced by NNK. Experimental Procedures: A/J female mice were used as a preclinical model for lung cancer immunoprevention due to their susceptibility to tobacco-carcinogen-induced lung cancer. A/J mice were i.p. injected with NNK weekly for eight consecutive treatments. The mice were also treated s.c. with 100 µg SA-4-1BBL twice, two weeks apart on weeks 6 and 8 of NNK treatment. Animals were monitored for 21 weeks and euthanized to harvest the lung and lung-draining lymph nodes for histology (H&E staining and PCNA immunofluorescence staining). In separate groups, mice were treated with a depleting antibody to CD4 twice two weeks apart on weeks 6 and 8 of NNK treatment to investigate the role of CD4+ immune cells in cancer immunoprevention. Results: NNK treatment resulted in lung tumor formation as assessed by PCNA immunofluorescence staining in all saline-injected control mice by the 21-week experimental end-point. Treatment with SA-4-1BBL resulted in significantly fewer macroscopic and microscopic tumor numbers than the control group (p < 0.01). Animals treated with SA-4-1BBL and subjected to CD4+ cell depletion showed similar numbers of macroscopic and microscopic lung tumors to the vehicle group. Conclusions: Prophylactic treatment with SA-4-1BBL significantly prevents NNK-induced lung tumor formation and CD4+ immune cells play a critical role in the observed immunoprevention efficacy of SA-4-1BBL. Supported by a grant from DOD LC190524 to Esma S. Yolcu. Citation Format: Ayse Ece Gulen, Mohammad Tarique, Vahap Ulker, Evrim Agca, Haval Shirwan, Esma S. Yolcu. Assessing immunoprevention efficacy of an agonist of CD137 pathway in a tobacco carcinogen-induced lung cancer preclinical model [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A007.

Abstract IA007: PREVENT agent development pipeline

Abstract The NCI’s PREVENT Cancer Preclinical Drug Development Program is a peer-reviewed program designed to support the preclinical development of promising agents and biomarkers for cancer interception/prevention towards clinical applications. PREVENT is not a grant program but allocates NCI contract resources to advance approved projects in a milestone-driven manner. Results obtained through NCI contract resources are returned to the applicant PIs and used to support further development by the applicants or in partnership with NCI. Resources available to PREVENT Program applicants include preclinical efficacy testing, CGMP manufacturing, GLP pharmacokinetic and IND-enabling toxicology studies, and IND filings. The PREVENT Program is focused on preventive agent development in the areas of Immunoprevention (cancer vaccines and immunomodulatory agents), Chemoprevention (novel mechanisms, anti-inflammatory agents, drug repurposing, toxicity reduction via alternative dosing regimens and agent combinations) and clinically translatable mechanistic biomarkers (pharmacodynamics, immune correlates, and tumor preventive efficacy). Submission deadlines for PREVENT Concept Applications occur twice per year on the second Monday in January and July. Further information can be obtained at the PREVENT Program website: https://prevention.cancer.gov/major-programs/prevent-cancer-preclinical Citation Format: Mark Stevn Miller, Brian Cholewa, John Clifford, Vignesh Gunasekharan, Altaf Mohammed, Shanker Gupta, Robert Shoemaker, Shizuko Sei. PREVENT agent development pipeline [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA007.

Abstract A004: Chemoprevention of head and neck cancers by the combination of epigallocatechin gallate (EGCG) and resveratrol

Abstract Head and neck cancer (HNC) is a devastating disease and the 6th most common cancer worldwide. Most HNC patients are diagnosed with advanced stage disease for which the 5-year survival is below 50%, stressing the need for chemoprevention. Recently, we have reported that the combination of resveratrol and EGCG induces synergistic apoptosis and inhibits xenografted HNC growth by inhibiting AKT-mTOR pathway. In this study, we have investigated the chemopreventive efficacy of resveratrol, EGCG and their combination using 4NQO-induced oral carcinogenesis model. C57BL/6 mice were exposed to 4-NQO (50 μg/ml) via drinking water for 10 weeks, followed by treatment with vehicle (50% sweetened condense milk), resveratrol (30 mg/kg), EGCG (30 mg/kg) and their combination for 8 weeks, 5 days/week. The mice were sacrificed on week 24 and the number of visible and microscopic lesions were counted. Resveratrol alone and in combination with EGCG significantly inhibited the number of visible lesions whereas the number of microscopic lesions and lesion area were significantly inhibited only in the combination group. Furthermore, RNASeq and qPCR analysis using a HNC cell line identified GDF15, ATF3, p21, p27 and Bim as significantly upregulated genes with GDF15 being the most upregulated one. Expression of GDF15 and ATF3 proteins were confirmed by western blotting. Taken together, our data strongly demonstrate the chemopreventive potential of the combination of EGCG and resveratrol and paves the way for further clinical developments. (Supported by NIH Grant P20GM103434 to the West Virginia IDeA Network for Biomedical Research Excellence) Citation Format: Adeoluwa Adeluola, Lukmon Raji, Saroj Sigdel, A.S.M. Anisuzzaman, A. R. M. Ruhul Amin. Chemoprevention of head and neck cancers by the combination of epigallocatechin gallate (EGCG) and resveratrol [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A004.