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We previously showed that elevated TYMS exhibits oncogenic properties and promotes tumorigenesis after a long latency, suggesting cooperation with sequential somatic mutations. Here we report the cooperation of ectopic expression of human TYMS with loss of Ink4a/Arf, one of the most commonly mutated somatic events in human cancer. Using an hTS/Ink4a/Arf−/− genetically engineered mouse model we showed that deregulated TYMS expression in Ink4a/Arf null background accelerates tumorigenesis and metastasis. In addition, tumors from TYMS-expressing mice were associated with a phenotype of genomic instability including enhanced double strand DNA damage, aneuploidy and loss of G1/S checkpoint. Downregulation of TYMS in vitro decreased cell proliferation and sensitized tumor cells to antimetabolite chemotherapy. In addition, depletion of TYMS in vivo by TYMS shRNA reduced tumor incidence, delayed tumor progression and prolonged survival in hTS/Ink4a/Arf−/− mice. Our data shows that activation of TYMS in Ink4a/Arf null background enhances uncontrolled cell proliferation and tumor growth, supporting the development of new agents and strategies targeting TYMS to delay tumorigenesis and prolong survival.

PDF file - 235K, mRNA expression levels in normal mammary glands, mammary tumors and tumors from zebularine treated mice.

Zebularine is a novel potent inhibitor of both cytidine deaminase and DNA methylation. We examined the effect of zebularine on mammary tumor growth in genetically engineered MMTV-PyMT transgenic mice that develop mammary tumors at 60 days of age with 100% penetrance. The MMTV-PyMT transgenic mice were randomized at 46 days of age into control (n = 25) and zebularine (n = 25) treatment groups and monitored for parameters of tumor growth. Zebularine was administered at 5 mg/mL in drinking water. We observed a significant delay in the growth of mammary tumors in zebularine-treated mice with a statistically significant reduction (P = 0.0135) in total tumor burden at 94 days of age when the mice were sacrificed. After 48 days of zebularine treatment, the tumors were predominantly necrotic compared with untreated animals. In addition, a high apoptotic index by terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay was observed as early as 13 days following treatment. Immunoblot analysis showed depletion of DNMT1 and partial depletion of DNMT3b after zebularine treatment. Microarray analyses of global gene expression identified upregulation of twelve methylation-regulated genes as well as a set of candidate cancer genes that participate in cell growth and apoptosis. In summary, zebularine inhibits the growth of spontaneous mammary tumors and causes early onset of tumor cell necrosis and apoptosis in a genetically engineered mouse model of breast cancer. Defining the parameters of zebularine-mediated tumor inhibition may advance the future development of DNA methyltransferase inhibitors as an effective cancer treatment. Mol Cancer Ther; 11(2); 370–82. ©2011 AACR.

PDF file - 262K, Differentially up-regulated genes (>1.5-fold differences; P < 0.05) from mammary tumors of the PyMT transgenic mice exposed to zebularine for 23 days.

PDF file - 401K, Differentially up-regulated genes (>1.5-fold differences; P < 0.05) from mammary tumors of the PyMT transgenic mice exposed to zebularine for 13 days.

PDF file - 396K, Differentially up-regulated genes (>1.5-fold differences; P < 0.05) from mammary tumors of the PyMT transgenic mice exposed to zebularine for 48 days.

PDF file - 428K, Differentially down-regulated genes (>1.5-fold differences; P < 0.05) from mammary tumors of the PyMT transgenic mice exposed to zebularine for 13 days.

PDF file - 310K, Differentially down-regulated genes (>1.5-fold differences; P < 0.05) from mammary tumors of the PyMT transgenic mice exposed to zebularine for 23 days.

MET tyrosine kinase domain modeling location of the F1200 residue

Demographics of the METex14-mutated and EGFR-mutated cohorts.

Purpose:Although patients with advanced-stage non–small cell lung cancers (NSCLC) harboring MET exon 14 skipping mutations (METex14) often benefit from MET tyrosine kinase inhibitor (TKI) treatment, clinical benefit is limited by primary and acquired drug resistance. The molecular basis for this resistance remains incompletely understood.Experimental Design:Targeted sequencing analysis was performed on cell-free circulating tumor DNA obtained from 289 patients with advanced-stage METex14-mutated NSCLC.Results:Prominent co-occurring RAS–MAPK pathway gene alterations (e.g., in KRAS, NF1) were detected in NSCLCs with METex14 skipping alterations as compared with EGFR-mutated NSCLCs. There was an association between decreased MET TKI treatment response and RAS–MAPK pathway co-occurring alterations. In a preclinical model expressing a canonical METex14 mutation, KRAS overexpression or NF1 downregulation hyperactivated MAPK signaling to promote MET TKI resistance. This resistance was overcome by cotreatment with crizotinib and the MEK inhibitor trametinib.Conclusions:Our study provides a genomic landscape of co-occurring alterations in advanced-stage METex14-mutated NSCLC and suggests a potential combination therapy strategy targeting MAPK pathway signaling to enhance clinical outcomes.

The MET F1200 residue is conserved across multiple tyrosine kinases

Genes included in NGS Panels

IntroductionLung cancer is the leading cause of cancer death in the USA and worldwide, and lung cancer screening (LCS) with low-dose CT (LDCT) has the potential to improve lung cancer outcomes. A critical question is whether the ratio of potential benefits to harms found in prior LCS trials applies to an older and potentially sicker population. The Personalised Lung Cancer Screening (PLuS) study will help close this knowledge gap by leveraging real-world data to fully characterise LCS recipients. The principal goal of the PLuS study is to characterise the comorbidity burden of individuals undergoing LCS and quantify the benefits and harms of LCS to enable informed decision-making.Methods and analysisPLuS is a multicentre observational study designed to assemble an LCS cohort from the electronic health records of ~40 000 individuals undergoing annual LCS with LDCT from 2016 to 2022. Data will be integrated into a unified repository to (1) examine the burden of multimorbidity by race/ethnicity, socioeconomic status and age; (2) quantify potential benefits and harms; and (3) use the observational data with validated simulation models in the Cancer Intervention and Surveillance Modeling Network (CISNET) to provide LCS outcomes in the real-world US population. We will fit a multivariable logistic regression model to estimate the adjusted ORs of comorbidity, functional limitations and impaired pulmonary function adjusted for relevant covariates. We will also estimate the cumulative risk of LCS outcomes using discrete-time survival models. To our knowledge, this is the first study to combine observational data and simulation models to estimate the long-term impact of LCS with LDCT.Ethics and disseminationThe study was approved by the Kaiser Permanente Southern California Institutional Review Board and VA Portland Health Care System. The results will be disseminated through publications and presentations at national and international conferences. Safety considerations include protection of patient confidentiality.

Up to 60% of patients with small cell lung cancer (SCLC) continue to smoke, which is associated with worse clinical outcomes. Platinum-based chemotherapies, in combination with topoisomerase inhibitors, are first-line therapies for SCLC, with rapid chemoresistance as a major barrier. We provided evidence in this study that nicotine and its major metabolite, cotinine, at physiologically relevant concentrations, reduced the efficacy of platinum-based chemotherapies and facilitated chemoresistance in SCLC cells. Mechanistically, nicotine or cotinine reduced chemotherapy-induced DNA damage by modulating cellular redox processes, with nAChRs as the upstream targets. Surprisingly, cisplatin treatment alone also increased the levels of nAChRs in SCLC cells, which served as a self-defense mechanism against platinum-based therapies. These discoveries were confirmed in long-term in vitro and in vivo studies. Collectively, our results depicted a novel and clinically important mechanism of chemoresistance in SCLC treatment: nicotine exposure significantly compromises the efficacy of platinum-based chemotherapies in SCLC treatment by reducing therapy-induced DNA damage and accelerating chemoresistance acquisition. The results also emphasized the urgent need for tobacco cessation and the control of NRT use for SCLC management.

KRAS mutations are the most common oncogenic drivers. Sotorasib (AMG510), a covalent inhibitor of KRAS

TPS280 Background: Patients with advanced colorectal cancer after progressing through first line therapy, have several FDA-approved systemic therapies that are associated with clinical benefit for a substantive minority of patients. Current clinical practice is to trial these various treatments in a step-wise fashion using CT scans every 3 months to evaluate effectiveness. This process requires 3-4 months between therapeutic interventions from which the patient may ultimately derive no clinical benefit, may have a performance status decline; limiting the number of possible interventions and increases risk for physical and financial toxicity. An alternative to the traditional CT-scan guided approach for disease assessment is a circulating tumor DNA (ctDNA) intervention. The Signatera ctDNA assay which utilizes 16 truncal mutations derived from a patient’s tumor, can be assessed every 2 weeks for a rapid determination of the effectiveness of a systemic therapy. This may allow patients to be exposed to many treatments during a short time, limiting toxicity, allowing for a quicker determination of clinical benefit and personalization of treatment. The aim of this study will be to compare the traditional scan-driven approach vs an intervention guided by ctDNA assessments, both arms using a pre-specified order of chemotherapy treatments. Methods: This is a phase 2 randomized study of patients with refractory metastatic adenocarcinoma of the colon or rectum. Participants are eligible after progression or intolerance to first line chemotherapy or recurrence within 6 months of adjuvant oxaliplatin based chemotherapy. They must have RECIST measurable metastatic disease that is not eligible for definitive management. Tissue from the primary and/or metastatic deposit is required for Signatera NGS analysis and subjects must have measurable ctDNA at sampling. Participants must be ≥18 years old without major organ dysfunction and have an ECOG performance status of 0 to 2. Subjects with Microsatellite High, deficient in DNA mismatch repair genes, or BRAF V600E mutations are excluded. Subjects will be randomized 1:1 to Arm A (ctDNA guided intervention) or Arm B (scan-guided control group). Patients in both arms will undergo systemic treatments in a standardized pre-specified order. Arm A will have ctDNA assessments every 2 weeks until an intervention shows a significant decrease, then every 4 weeks until Progressive Disease (PD) by scan or significant ctDNA increase. CT imaging will be performed every 12 weeks. Those in Arm B, will have CT imaging every 12 weeks and blood collected for post-hoc analysis every 4 weeks until PD by scan. The primary endpoint is overall survival. Secondary endpoints include progression free survival and overall response. Exploratory analysis with be performed of the microbiome. Enrollment continues to a maximum of 78 patients. Clinical trial information: NCT04786600 .

Lung cancer with loss-of-function of the LKB1 tumor suppressor is a common aggressive subgroup with no effective therapies. LKB1-deficiency induces constitutive activation of cAMP/CREB-mediated transcription by a family of three CREB-regulated transcription coactivators (CRTC1-3). However, the significance and mechanism of CRTC activation in promoting the aggressive phenotype of LKB1-null cancer remain poorly characterized. Here, we observed overlapping CRTC expression patterns and mild growth phenotypes of individual CRTC-knockouts in lung cancer, suggesting functional redundancy of CRTC1-3. We consequently designed a dominant-negative mutant (dnCRTC) to block all three CRTCs to bind and co-activate CREB. Expression of dnCRTC efficiently inhibited the aberrantly activated cAMP/CREB-mediated oncogenic transcriptional program induced by LKB1-deficiency, and specifically blocked the growth of human and murine LKB1-inactivated lung cancer. Collectively, this study provides direct proof for an essential role of the CRTC-CREB activation in promoting the malignant phenotypes of LKB1-null lung cancer and proposes the CRTC-CREB interaction interface as a novel therapeutic target.

Objective There are no effective systemic therapies for adenoid cystic cancer (ACC) and lack of tumor lines and mouse models have hindered drug development. We aim to develop MYB-activated models for testing new therapeutic agents. Materials and methods We studied new ACC patient-derived xenograft (PDX) models and generated a matched cell line from one patient. In addition, we generated a genetically-engineered MYB-NFIB mouse model (GEMM) that was crossed with Ink4a+/−/Arf+/− mice to study tumor spectrum and obtain tumor lines. Using human and murine ACC-like tumor lines, we analyzed MYB expression by RNA-Seq and immunoblot and tested efficacy of new MYB inhibitors. Results We detected MYB-NFIB transcripts in both UFH1 and UFH2 PDX and observed tumor inhibition by MYB depletion using shRNA in vivo. We observed rapid loss of MYB expression when we cultured UFH1 in vitro, but were able to generate a UFH2 tumor cell line that retained MYB expression for 6 months. RNA-Seq expression detected an ACC-like mRNA signature in PDX samples and we confirmed an identical KMT2A/MLL variant in UFH2 PDX, matched cell line, and primary biopsy. Although the predominant phenotype of the MYB-NFIB GEMM was B-cell leukemia, we also generated a MYB-activated ACC-like mammary tumor cell line. We observed tumor inhibition using a novel MYB peptidomimetic in both human and murine tumor models. Conclusions We generated and studied new murine and human MYB-activated tumor samples and detected growth inhibition with MYB peptidomimetics. These data provide tools to define treatment strategies for patients with advanced MYB-activated ACC.

Purpose: Mutations in KRAS are the most common oncogenic drivers. Sotorasib (AMG510), a covalent inhibitor selectively targeting KRASG12C, was recently approved for the treatment of KRASG12C-mutated non-small cell lung cancer (NSCLC). However, the clinical efficacy of sotorasib and other KRASG12C inhibitors is limited by intrinsic resistance in colorectal cancer (CRC) and by the rapid emergence of acquired resistance in all treated solid tumors. Therefore, there is an urgent need to develop novel combination therapies to overcome sotorasib resistance and to maximize its efficacy. Experimental Design: A panel of KRASG12C-mutated cell lines from NSCLC, CRC and pancreatic cancer (PC) were treated with sotorasib alone or in combination with BCL-XL proteolysis targeting chimera (PROTAC, such as DT2216) to assess effects on cell viability, colony formation and apoptosis. To identify mechanisms underlying sotorasib+DT2216 combination responses, we analyzed KRAS downstream signaling and expression of BCL-2 family proteins, and performed co-immunoprecipitation of BCL-XL to evaluate its interaction with pro-apoptotic BH3-only proteins. Finally, therapeutic efficacy of sotorasib alone and in combination with DT2216 was evaluated in vivo using different tumor xenograft models. Results: We observed heterogeneous responses to sotorasib alone, whereas its combination with DT2216 strongly inhibited viability of KRASG12C cell lines that partially responded to sotorasib treatment. Mechanistically, co-treatment with DT2216 inhibited sotorasib-induced BCL-XL/BIM interaction leading to enhanced apoptosis. Furthermore, DT2216 co-treatment significantly improved the antitumor efficacy of sotorasib in vivo. Conclusions: Our findings suggest that due to cytostatic activity, the efficacy of sotorasib is limited, and therefore its combination with a pro-apoptotic agent DT2216 shows synergistic responses and can potentially overcome resistance. Citation Format: Sajid Khan, Janet Wiegand, Peiyi Zhang, Wanyi Hu, Dinesh Thummuri, Vivekananda Budamagunta, Nan Hua, Lingtao Jin, Carmen J. Allegra, Edmund S. Kopetz, Maria Zajac-Kaye, Frederic J. Kaye, Guangrong Zheng, Daohong Zhou. A BCL-XL PROTAC degrader DT2216 synergizes with KRASG12C inhibitors for effectively treating KRASG12C-mutated cancers [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 5313.

Thymidylate synthase (TS) inhibitors are an integral component of chemotherapy regimens for difficult to treat cancer subtypes. Despite initial therapeutic benefit, current inhibitors induce TS overexpression or alter folate transport metabolism feedback pathways that tumor cells exploit for drug resistance. Here we report a small molecule TS inhibitor that exhibits i) enhanced antitumor activity as compared to current fluoropyrimidines and antifolates without inducing TS overexpression, ii) is structurally distinct from classical antifolates, iii) extends survival in a pancreatic tumor mouse model, iv) and is well tolerated with equal efficacy using either intraperitoneal or oral administration. Mechanistically, we confirm the compound is a multifunctional non classical antifolate and through a series of analogues identify structural features allowing direct TS inhibition while also maintaining the ability to inhibit dihydrofolate reductase (DHFR). Collectively, this work identifies new non classical antifolate inhibitors that optimize inhibition of thymidylate biosynthesis with a favorable safety profile highlighting potential for enhanced cancer therapy. Citation Format: Maria V. Guijarro, Patrick C. Kellish, Peter E. Dib, Nicholas G. Paciaroni, Akbar Nawab, Jacob Andring, Lidia Kulemina, Nicholas V. Borrero, Carlos Modenutti, Richard L. Bennett, Daniil Shabashvili, Jonathan D. Licht, Robert McKenna, Adrian Roitberg, Robert W. Huigens, Frederic J. Kaye, Maria Zajac-Kaye. First in class multifunctional non classical antifolates inhibits thymidylate synthase and extends survival in pancreatic cancer model [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 4055.

12129 Background: Depression, anxiety, and fear of cancer recurrence (FCR) constitute prevalent psychological concerns necessitating further attention in developing supportive care interventions for women with gynecologic, gastrointestinal, and thoracic cancers. Recent evidence indicates that such concerns may be especially severe among underserved women of color and women affected by low-socioeconomic status (SES). The purpose of the present study is to evaluate the magnitude of changes in depression, anxiety, and FCR associated with a mindfulness-based yoga intervention among a diverse sample of women with these cancers. A second aim is to identify how changes in these concerns may differ across sociodemographic groups. Methods: Women with gynecologic ( n=86), gastrointestinal ( n=17), or thoracic ( n=20) cancers were enrolled in a group-based 10-week yoga intervention utilizing mindfulness meditation, relaxation, and gentle yoga. Prior to and following intervention, participants were administered assessments, including the Beck Depression Inventory – Second Edition (BDI-II) to measure depression, the State-Trait Anxiety Inventory (STAI) to assess anxiety, and the Fear of Cancer Recurrence Inventory (FCRI) to evaluate aspects of FCR. Mixed-linear models evaluated change in outcomes from pre- to post-intervention, with conditional models assessing the effects of age, race/ethnicity, and SES on change. Analyses were conducted prior to trial completion due to approaching accrual period termination. Results: The sample demonstrated a mean age of 58.46 ( SD=10.82) and mean SES score of 3.98 ( SD=1.55) using a 1 to 7 composite scale. Twenty-six percent of participants were of racial and/or ethnic minority status ( n=32). Significant declines in total depressive symptoms, somatic depressive symptoms, state anxiety, and psychological distress due to FCR were observed across the sample. Higher SES was associated with significantly greater reductions in total depressive symptoms and affective depressive symptoms, specifically. Women of color experienced significantly greater declines in somatic symptoms compared to non-Hispanic White women. Conclusions: This mindfulness-based yoga intervention was associated with significant reductions in depressive symptoms, state anxiety, and psychological distress related to FCR among women with gynecologic, gastrointestinal, and thoracic cancers. Higher SES and underserved race/ethnicity status moderated some of these effects. Future research should explore the efficacy of this intervention among diverse women in a randomized clinical trial context. Clinical trial information: NCT03385577.

e24125 Background: Gynecologic, gastrointestinal (GI), and thoracic cancers account for significant morbidity and mortality in the U.S. Women with these types of cancers frequently experience psychological distress, among other poor outcomes. Previous research has indicated that mindfulness-based interventions, such as yoga, can be effective in decreasing distress in cancer patients. Notably, this research has primarily been conducted in a breast cancer population with limited research assessing the feasibility, acceptability, and/or efficacy of this type of intervention in other prevalent and impactful cancers among women. The purpose of the present study was to assess the Feasibility and Acceptability of a yoga intervention for women with gynecologic, GI, or thoracic cancers. Methods: A total of 124 women diagnosed with a gynecologic, GI, or thoracic cancer in the prior year were recruited via outpatient oncology clinics to participate in a 10-week, group-based manualized yoga intervention entitled “Stilling the Waters of Uncertainty” (Author: E. Kacel) that is nearing the end of accrual. Participants completed an Acceptability evaluation following each yoga session with ratings on a 5-point Likert scale from “not at all” to “extremely.” Feasibility of the study was operationalized as percentage of eligible participants who (a) enrolled, (b) attended sessions, and (c) completed post-intervention assessment. Acceptability was operationalized as the percentage of participants with average session ratings of “very” or “extremely” for intervention usefulness, enjoyableness, safety, clarity, relevance, and likelihood of continuing to practice skills. Criteria for operationalizing Feasibility and Acceptability for this study were defined a priori based on recommendations of Bowen and colleagues (2009). A minimum of 80% for each measure of feasibility and acceptability was set as the a priori threshold of success in each domain. Results: All measures of Feasibility were below the a priori benchmark of 80%: Of the 318 eligible patients approached for participation, (a) 124 patients (39.0%) enrolled; 49/124 (39.5%) attended at least 1 yoga session; 44/124 (35.4%) attended at least 8 sessions; and (c) 41/124 (33.1%) completed post-intervention assessment procedures. At least 80% of attendees rated the intervention as “very” or “extremely” useful, enjoyable, safe, and clear; 75.5% and 79.6% of attendees rated the intervention as “very” or “extremely” relevant and likely to be continued to be practiced. Conclusions: The results of this study indicate that a yoga intervention for women with prevalent non-breast cancer types did not meet a priori criteria for feasibility. However, participants who attended at least 1 session rated the intervention as generally acceptable. Future research is needed to improve study/intervention feasibility in this population. Clinical trial information: NCT03385577.

Aberrant activation of CDK4/6 kinase is the most common somatic event in non-small cell lung cancer (NSCLC). Palbociclib is a highly specific CDK4/6 inhibitor shown to inhibit cell cycle progression and promote cellular senescence. We conducted a phase 2 clinical trial of palbociclib in 19 previously-treated patients with advanced NSCLC. Only patients with p16-null staining by immunohistochemistry and documented tumor progression were eligible. The primary endpoint was tumor response rate. Palbociclib therapy alone was well-tolerated. Of 16 evaluable patients who received > 1 month of therapy, there were no objective responses. However, 8 patients (50%) with previously progressive NSCLC had stable disease (SD) lasting a range of 4-10.5 months. Median overall survival (OS) for all cases was 5.1 months, and median overall survival for the subset of patients with SD was 16.6 months. We also performed preclinical testing of palbociclib in combination with 13 different targeted or cytotoxic chemotherapeutic agents using a cell viability assay. Only the combination of palbociclib and mTOR inhibitors resulted in synergistic growth inhibition, particularly in tumors carrying RAS mutations. Our findings warrant further clinical investigation of the combination of palbociclib and mTOR inhibitors, especially in patients carrying activated RAS mutations.

No effective systemic treatment is available for patients with unresectable, recurrent, or metastatic mucoepidermoid carcinoma (MEC), the most common salivary gland malignancy. MEC is frequently associated with a t(11;19)(q14-21;p12-13) translocation that creates a CRTC1-MAML2 fusion gene. The CRTC1-MAML2 fusion exhibited transforming activity in vitro; however, whether it serves as an oncogenic driver for MEC establishment and maintenance in vivo remains unknown. Here, we show that doxycycline-induced CRTC1-MAML2 knockdown blocked the growth of established MEC xenografts, validating CRTC1-MAML2 as a therapeutic target. We further generated a conditional transgenic mouse model and observed that Cre-induced CRTC1-MAML2 expression caused 100% penetrant formation of salivary gland tumors resembling histological and molecular characteristics of human MEC. Molecular analysis of MEC tumors revealed altered p16-CDK4/6-RB pathway activity as a potential cooperating event in promoting CRTC1-MAML2-induced tumorigenesis. Cotargeting of aberrant p16-CDK4/6-RB signaling and CRTC1-MAML2 fusion-activated AREG/EGFR signaling with the respective CDK4/6 inhibitor Palbociclib and EGFR inhibitor Erlotinib produced enhanced antitumor responses in vitro and in vivo. Collectively, this study provides direct evidence for CRTC1-MAML2 as a key driver for MEC development and maintenance and identifies a potentially novel combination therapy with FDA-approved EGFR and CDK4/6 inhibitors as a potential viable strategy for patients with MEC.

Lung cancer with loss-of-function of the LKB1 tumor suppressor is a common aggressive subgroup with no effective therapies. LKB1-deficiency induces constitutive activation of cAMP/CREB-mediated transcription by a family of three CREB-regulated transcription coactivators (CRTC1-3). However, the significance and mechanism of CRTC activation in promoting the aggressive phenotype of LKB1-null cancer remain poorly characterized. Here we observed overlapping CRTC expression patterns and mild growth phenotypes of individual CRTC-knockouts in lung cancer, suggesting functional redundancy of CRTC1-3. We consequently designed a dominant-negative mutant (dnCRTC) to block all three CRTCs to bind and co-activate CREB. Expression of dnCRTC efficiently inhibited the aberrantly activated cAMP/CREB-mediated oncogenic transcriptional program induced by LKB1-deficiency, and specifically blocked the growth of LKB1-inactivated lung cancer. Collectively, this study provides direct proof for an essential role of the CRTC-CREB activation in promoting the malignant phenotypes of LKB1-null lung cancer and proposes the CRTC-CREB interaction interface as a novel therapeutic target.

Purpose Delta-like protein 3 (DLL3) is being developed as a predictive biomarker for DLL3-targeting antibody-drug conjugate and other therapies. Given the neuroendocrine features of Merkel cell carcinoma (MCC), we sought to evaluate DLL3 expression and its role in MCC. Experimental Design Formalin-fixed and paraffin-embedded MCC cases were consecutively selected. Immunohistochemistry was performed for DLL3 (SC16.65 antibody) and polyomavirus large T-antigen (sc-136172 antibody). Slides were read out for percentage of positive tumor cells. Cox proportional hazards model was applied to assess the association between DLL3 expression and overall survival (OS). A patient with a DLL3-expressing MCC was treated with rovalpituzumab tesirine (Rova-T) in the “other tumor” cohort of NCT02709889 and assessed for response. Results The median H-score of DLL3 expression of 65 patients included was 60 (interquartile range, 30–100). Fifty-eight cases (89%) had ≥1% tumor cells positive for DLL3 expression with any intensity, of which the median DLL3 expression was 50% (interquartile range, 25%–70%). Thirty-four cases (52%) had ≥50% tumor cells positive for DLL3 expression with any intensity. Higher H-score of DLL3 expression was associated with higher polyomavirus nuclear expression (p = .003) when it was dichotomized to negative versus positive. H-score of DLL3 expression did not predict OS of patients with MCC (p = .4) after being adjusted for common clinicopathological factors. A patient treated with Rova-T for refractory metastatic MCC achieved partial response. Conclusions DLL3 overexpression is very common in MCC by immunohistochemistry. The response to treatment suggests that DLL3 expression may have predictive relevance for DLL3-targeting therapies in MCC. Implications for Practice Delta-like protein 3 (DLL3) is being developed as a predictive biomarker to identify patients for treatment with DLL3-targeting agents. Merkel cell carcinoma (MCC) is an aggressive neuroendocrine carcinoma of the skin. It was found that DLL3 overexpression is very common in MCC by immunohistochemistry and significantly associated with Merkel cell polyomavirus expression. Despite the lack of prognostic significance in this cohort, DLL3 expression may have predictive relevance for DLL3-targeting therapies in MCC. The high levels of DLL3 expression in a subset of MCC may potentially be used to select patients to receive DLL3-targeting therapies.

TPS223 Background: Patients with advanced colorectal cancer after progressing through first line therapy, have several FDA-approved systemic therapies that are associated with clinical benefit for a substantive minority of patients. Current clinical practice is to trial these various treatments in a step-wise fashion using CT scans every 3 months to evaluate effectiveness. This process requires 3-4 months between therapeutic interventions from which the patient may ultimately derive no clinical benefit, may have a performance status decline; limiting the number of possible interventions and increases risk for physical and financial toxicity. An alternative to the traditional CT-scan guided approach for disease assessment is a circulating tumor DNA (ctDNA) intervention. The Signatera ctDNA assay which utilizes 16 truncal mutations derived from a patient’s tumor, can be assessed every 2 weeks for a rapid determination of the effectiveness of a systemic therapy. This may allow patients to be exposed to many treatments during a short time, limiting toxicity, allowing for a quicker determination of clinical benefit and personalization of treatment. The aim of this study will be to compare the traditional scan-driven approach vs an intervention guided by ctDNA assessments, both arms using a pre-specified order of chemotherapy treatments. Methods: This is a phase 2 randomized study of patients with refractory metastatic adenocarcinoma of the colon or rectum. Participants are eligible after progression or intolerance to first line chemotherapy or recurrence within 6 months of adjuvant oxaliplatin based chemotherapy. They must have RECIST measurable metastatic disease that is not eligible for definitive management. Tissue from the primary and/or metastatic deposit is required for Signatera NGS analysis and subjects must have measurable ctDNA at sampling. Participants must be ≥18 years old without major organ dysfunction and have an ECOG performance status of 0 to 2. Subjects with Microsatellite High, deficient in DNA mismatch repair genes, or BRAF V600E mutations are excluded. Subjects will be randomized 1:1 to Arm A (ctDNA guided intervention) or Arm B (scan-guided control group). Patients in both arms will undergo systemic treatments in a standardized pre-specified order. Arm A will have ctDNA assessments every 2 weeks until an intervention shows a significant decrease, then every 4 weeks until Progressive Disease (PD) by scan or significant ctDNA increase. CT imaging will be performed every 12 weeks. Those in Arm B, will have CT imaging every 12 weeks and blood collected for post-hoc analysis every 4 weeks until PD by scan. The primary endpoint is overall survival. Secondary endpoints include progression free survival and overall response. Exploratory analysis with be performed of the microbiome. Enrollment continues to a maximum of 78 patients. Clinical trial information: NCT04786600.

Background The LKB1 tumor suppressor gene is commonly inactivated in non-small cell lung carcinomas (NSCLC), a major form of lung cancer. Targeted therapies for LKB1-inactivated lung cancer are currently unavailable. Identification of critical signaling components downstream of LKB1 inactivation has the potential to uncover rational therapeutic targets. Here we investigated the role of INSL4, a member of the insulin/IGF/relaxin superfamily, in LKB1-inactivated NSCLCs. Methods INSL4 expression was analyzed using global transcriptome profiling, quantitative reverse transcription PCR, western blotting, enzyme-linked immunosorbent assay, and RNA in situ hybridization in human NSCLC cell lines and tumor specimens. INSL4 gene expression and clinical data from The Cancer Genome Atlas lung adenocarcinomas (n = 515) were analyzed using log-rank and Fisher exact tests. INSL4 functions were studied using short hairpin RNA (shRNA) knockdown, overexpression, transcriptome profiling, cell growth, and survival assays in vitro and in vivo. All statistical tests were two-sided. Results INSL4 was identified as a novel downstream target of LKB1 deficiency and its expression was induced through aberrant CRTC-CREB activation. INSL4 was highly induced in LKB1-deficient NSCLC cells (up to 543-fold) and 9 of 41 primary tumors, although undetectable in all normal tissues except the placenta. Lung adenocarcinomas from The Cancer Genome Atlas with high and low INSL4 expression (with the top 10th percentile as cutoff) showed statistically significant differences for advanced tumor stage (P Conclusions LKB1 deficiency induces an autocrine INSL4 signaling that critically supports the growth and survival of lung cancer cells. Therefore, aberrant INSL4 signaling is a promising therapeutic target for LKB1-deficient lung cancers.

Small cell lung cancer (SCLC) accounts for approximately 15% of all lung cancers and demands effective targeted therapeutic strategies. In this meta-analysis study, we aim to identify significantly mutated genes and regulatory pathways to help us better understand the progression of SCLC and to identify potential biomarkers. Besides ranking genes based on their mutation frequencies, we sought to identify statistically significant mutations in SCLC with the MutSigCV software. Our analysis identified several genes with relatively low mutation frequency, including PTEN, as highly significant (p 0.001), suggesting these genes may play an important role in the progression of SCLC. Our results also indicated mutations in genes involved in the axon guidance pathways likely play an important role in SCLC progression. In addition, we observed that the mutation rate was significantly higher in samples with RB1 gene mutated when compared to samples with wild type RB1, suggesting that RB1 status has significant impact on the mutation profile and disease progression in SCLC.

Despite efforts to use adeno-associated viral (AAV) vector–mediated gene therapy for treatment of pancreatic ductal adenocarcinoma (PDAC), transduction efficiency remains a limiting factor and thus improvement of AAV delivery would significantly facilitate the treatment of this malignancy. Site-directed mutagenesis of specific tyrosine (Y) residues to phenylalanine (F) on the surface of various AAV serotype capsids has been reported as a method for enhancing gene transfer efficiencies. In the present studies, we determine whether Y-to-F mutations could also enhance AAV8 gene transfer in the pancreas to facilitate gene therapy for PDAC. Three different Y-to-F mutant vectors (a single-mutant, Y733F; a double-mutant, Y447F+Y733F; and a triple-mutant, Y275F+Y447F+Y733F) and wild-type AAV8 (WT-AAV8) were administered by intraperitoneal or tail-vein routes to KrasG12D+/−, KrasG12D+/−/Pten+/−, and wild-type mice. The transduction efficiency of these vectors expressing the mCherry reporter gene was evaluated 2 weeks post administration in pancreas or PDAC and correlated with viral genome copy numbers. Our comparative and quantitative analyses of the transduction profiles demonstrated that the Y-to-F double-mutant exhibited the highest mCherry expression in pancreatic tissues (range 45–70%) compared with WT-AAV8 (7%; p

SMARCA4-deficient thoracic sarcoma (SMARCA4-DTS) is a recently described entity with a poor prognosis that is defined by certain genetic alterations in the BAF chromatin remodeling complex, specifically SMARCA4 and SMARCA2. We present a case of a SMARCA4-DTS in a 59 year-old male with a heavy smoking history who was found to have an unexpected right upper lobe lung mass on routine chest radiograph after a visit to his primary care physician. This led to a biopsy with a diagnosis of poorly differentiated carcinoma at an outside institution. The patient was subsequently seen at our facility for surgical intervention. The right upper lobectomy contained a 7.2-cm poorly differentiated malignancy with slightly discohesive cells arranged in sheets and nests, abundant geographic necrosis, and with many areas showing rhabdoid morphology. The tumor was focally reactive for CK7, AE1/3, Cam5.2, and SALL4 and showed scattered reactivity for CD34 and SOX2. There was complete loss of reactivity for both SMARCA4 and SMARCA2. The histology and immunophenotype were all consistent with the diagnosis of a SMARCA4-DTS. Next-generation sequencing showed a frameshift mutation in the SMARCA4 gene and no abnormality with the SMARCA2 gene. Interestingly, this tumor was confined to the pulmonary parenchyma with no invasion of the visceral pleura nor the mediastinum and with no clinically apparent metastases at the time of presentation. This case is presented to add to the cohort of cases described to date and to discuss the immunohistochemical and molecular findings with regard to SMARCA2.

Purpose: Although patients with advanced-stage non–small cell lung cancers (NSCLC) harboring MET exon 14 skipping mutations (METex14) often benefit from MET tyrosine kinase inhibitor (TKI) treatment, clinical benefit is limited by primary and acquired drug resistance. The molecular basis for this resistance remains incompletely understood. Experimental Design: Targeted sequencing analysis was performed on cell-free circulating tumor DNA obtained from 289 patients with advanced-stage METex14-mutated NSCLC. Results: Prominent co-occurring RAS–MAPK pathway gene alterations (e.g., in KRAS, NF1) were detected in NSCLCs with METex14 skipping alterations as compared with EGFR-mutated NSCLCs. There was an association between decreased MET TKI treatment response and RAS–MAPK pathway co-occurring alterations. In a preclinical model expressing a canonical METex14 mutation, KRAS overexpression or NF1 downregulation hyperactivated MAPK signaling to promote MET TKI resistance. This resistance was overcome by cotreatment with crizotinib and the MEK inhibitor trametinib. Conclusions: Our study provides a genomic landscape of co-occurring alterations in advanced-stage METex14-mutated NSCLC and suggests a potential combination therapy strategy targeting MAPK pathway signaling to enhance clinical outcomes.

Receptor EphA2 is overexpressed in lung cancer and malignant pleural mesothelioma (MPM) which promote tumorogenesis. Lipoplatin™, a new liposomal cisplatin formulation, is used against resistant tumors. Use of cisplatin-based drugs leads to unacceptable toxicities. To improve the effectiveness of Lipoplatin, enhancing the cellular sensitivity of lung tumor and MPM cells is critical. Therefore, we targeted receptor EphA2 by silencing interference RNA (siRNA) and treated tumor cells with Lipoplatin. The combined effects of siRNA-EphA2 and Lipoplatin were determined. We report that silencing EphA2 significantly enhanced the cellular sensitivity of lung tumor and MPM cells to Lipoplatin and maybe a potential therapy for lung cancer.

The purpose of this study is to report our institutional experience using radiotherapy in the treatment of ameloblastoma and ameloblastic carcinoma. Three patients with ameloblastoma and 3 patients with ameloblastic carcinoma were treated with radiotherapy alone (2 patients) or surgery and postoperative radiotherapy (4 patients) at the University of Florida between 1973 and 2007. Follow-up ranged from 4.0 to 13.1 years with a median of 7.8 years. Radiotherapy complications were scored using the Common Terminology Criteria for Adverse Events, version 4.0. Local control was achieved in 4 of the 6 patients. One patient treated with RT alone for an unresectable ameloblastoma developed a local recurrence and metastases in both the cervical lymph nodes and lungs, but had excellent response to dual BRAF/MEK inhibition with dabrafenib and trametinib. Another patient treated with surgery and postoperative radiotherapy for an ameloblastic carcinoma recurred locally without metastasis, but was not salvaged. No significant treatment-related complications were observed. For patients with local recurrence or inadequate margins after surgery, adjuvant radiotherapy provides the potential for disease control. In the setting of metastatic disease, targeted therapies may provide an additional opportunity for salvage.

e22061 Background: BRCA-associated protein-1 (BAP1) is a ubiquitin ligase associated with regulating cell cycle, cell proliferation, DNA damage pathway, and cell death. It also acts as a tumor suppressor gene as seen in hereditary cancer syndrome associated with germline mutations in BAP1. Preclinical studies have shown that PARP-inhibitor treatment of BAP1 mutant cell lines demonstrated significant synthetic lethality, independent of underlying BRCA status suggesting this mutation confers a BRCA-like phenotype. BAP1 is mutated, leading to a loss of functional protein, in up to 30% of several solid tumors including cholangiocarcinoma, mesothelioma, uveal melanoma, and clear cell renal cell carcinoma. Methods: This phase 2, open-label, single arm study aims to exploit the concept of synthetic lethality with the use of the PARP inhibitor niraparib in two biologically distinct cohorts. Eligible patients (pts) with measurable metastatic and incurable solid tumors are assigned to one of the two cohorts: Cohort A (histology-specific): tumors harboring suspected BAP1 mutations including cholangiocarcinoma, uveal melanoma, mesothelioma or clear cell renal cell carcinoma with tissue available for BAP1 mutational assessment via Next Generation Sequencing (NGS); or Cohort B (histology-agnostic): tumors with known DNA damage response (DDR) mutations (Table) confirmed by CLIA-approved NGS. Key inclusion criteria also include age ≥18 years, adequate cardiac, renal, hepatic function and ECOG PS of 0 to 1. Key exclusion criteria include known BRCA1 or BRCA2 mutations or prior PARPi exposure. Pts receive niraparib 200-300mg daily (depending on weight and/or platelet count) continuously. Primary endpoint is objective response rate (ORR), and secondary endpoints are progression free survival (PFS), overall survival (OS), toxicity and exploratory biomarker determinations. Radiographic response by RECIST criteria is measured every 8 weeks while on treatment. Cohort B enrollment is closed. Enrollment in Cohort A continues. A maximum of 47 evaluable subjects is planned with expansion cohorts allowable for histologic or molecular subtypes meeting pre-specified responses. Clinical trial information: NCT03207347. [Table: see text]

Adaptive stress signaling networks directly influence tumor development and progression. These pathways mediate responses that allow cancer cells to cope with both tumor cell-intrinsic and cell-extrinsic insults and develop acquired resistance to therapeutic interventions. This is mediated in part by constant oncogenic rewiring at the transcriptional level by integration of extracellular cues that promote cell survival and malignant transformation. The cAMP-regulated transcriptional coactivators (CRTCs) are a newly discovered family of intracellular signaling integrators that serve as the conduit to the basic transcriptional machinery to regulate a host of adaptive response genes. Thus, somatic alterations that lead to CRTC activation are emerging as key driver events in the development and progression of many tumor subtypes.

A higher incidence of Rhesus group D (RHD)-negative blood group among patients with Small Cell Cancer of the lung (SCLC) had been previously reported but reproducibility was not confirmed, and clinical relevance is undefined. We tested 1,090 (SCLC; Adenocarcinoma: Squamous = 202:536:352) cases of lung cancer over a 3-year period at a single institution and noted a higher frequency RHD negative status among SCLC cases (19/89) compared with non-SCLC (61/480) that could not be explained by differences in ethnic background in the patient population. While we confirmed poor ECOG functional status, advanced stage, elevated alkaline phosphatase, and low albumin levels as independent and significant factors for reduced overall survival (OS), we did not detect any clinical outcome correlations with RHD status in our dataset. Patients with SCLC rarely undergo surgical resection resulting in limited data for blood group analyses. We have now detected a higher rate of RHD-negative status in patients with SCLC compared with all other subtypes of lung cancer. The clinical and biological basis for this observation is undefined and we feel that this may be explained by variations in ethnic background.