Summer Cancer Research Experience for High School Students from Historically Marginalized Populations in Kansas City

The Accelerate Cancer Education (ACE) summer research program at The University of Kansas Cancer Center (KUCC) is a six-week, cancer-focused, summer research experience for high school students from historically marginalized populations in the Kansas City metropolitan area. Cancer affects all populations and continues to be the second leading cause of death in the United States, and a large number of disparities impact racial and ethnic minorities, including increased cancer incidence and mortality. Critically, strategies to bolster diversity, equity, inclusion, and accessibility are needed to address persistent cancer disparities. The ACE program offers an educational opportunity for a population of students who otherwise would not have easy access onto a medical center campus to make connections with cancer physicians and researchers and provides a vital response to the need for a more diverse and expansive oncology workforce. Students grow their technical, social, and professional skills and develop self-efficacy and long-lasting connections that help them matriculate and persist through post-secondary education. Developed in 2018, the ACE program has trained 37 high school junior and senior students. This article describes the need for and how we successfully developed and implemented the ACE program.

Cancer Prevention Perspective: The University of Kansas Cancer Center

Despite the incredible progress that has been made against cancer over the last few decades, the demographic trends in the United States predict that we will see significant increases in cancer incidence and mortality by the year 2030. This, coupled with an aging cancer workforce, would suggest that we will have major challenges ahead in dealing with the increasing burden from cancer. Clearly a critical part of our strategy must be to focus on cancer prevention and control (CPC) efforts and not solely rely on treatment to mitigate this concerning trend. This review discusses how the University of Kansas Cancer Center has had a longstanding emphasis on CPC and has leveraged this expertise to enhance the effectiveness and impact of our community outreach and engagement efforts.

A community engagement training program for basic and translational cancer researchers

PURPOSE

There is an increasing awareness of the importance of patient engagement in cancer research, but many basic and translational researchers have never been trained to do so. To address this unmet need, a 1-year patient engagement training program for researchers was developed.

METHODS

Eleven researchers and eleven paired research advocates participated. This program, designed for virtual delivery, included 3 didactic modules focused on (1) Community Outreach and Engagement principles and methods, (2) Communication skills, and (3) Team Science. This was followed by longitudinal projects to be completed by the researcher/advocate pairs, including learning about the research project, and co-authoring abstracts, manuscripts and grant proposals. Monthly group meetings allowed pairs to share their experiences. The program culminated in the pairs creating and presenting oral abstracts for the University of Kansas Cancer Center's Annual Research Symposium.

RESULTS

All participants indicated that the modules had a positive impact on their ability to collaborate in research. Both researcher self-evaluations and patient advocate evaluations of their researcher partner showed an improvement in researcher communication competency. Results from the Patient Engagement in Research Scale showed that advocates were highly engaged. Within 1 year after program completion, participating pairs have completed four abstracts and 9 grant proposals.

CONCLUSION

The program will be modified based on participant feedback, and can be adapted for future cohorts if an increased number of sessions per month and shortened program duration are desired. The program's virtual format allows scalability across institutions to potentially benefit large cohorts of researchers.

Understanding and Overcoming Immunosuppression Shaped by Cancer Stem Cells

Use of immunotherapy in recent years has revolutionized cancer treatment for certain types of cancers. However, the broad utility of immunotherapy is limited because there are still many types of cancer that do not respond effectively. Failure of a cancer to respond is due, at least in part, to its phenotypic plasticity, a feature that is established by cancer stem cells (CSC) and their associated microenvironments. This article discusses the current understanding of CSC-mediated immune evasion and provides a prospective view on how researchers can better understand and overcome the intrinsic immune privilege of CSCs and the extrinsic immune-suppressive microenvironment shaped by them.

Leadership Diversity and Development in the Nation's Cancer Centers

The capacity and diversity of the oncology leadership workforce has not kept pace with the emerging needs of our increasingly complex cancer centers and the spectrum of challenges our institutions face in reducing the cancer burden in diverse catchment areas. Recognizing the importance of a diverse workforce to reduce cancer inequities, the Association of American Cancer Institutes conducted a survey of its 103 cancer centers to examine diversity in leadership roles from research program leaders to cancer center directors. A total of 82 (80%) centers responded, including 64 National Cancer Institute-designated and 18 emerging centers. Among these 82 respondents, non-Hispanic White individuals comprised 79% of center directors, 82% of deputy directors, 72% of associate directors, and 72% of program leaders. Women are underrepresented in all leadership roles (ranging from 16% for center directors to 45% for associate directors). Although the limited gender, ethnic, and racial diversity of center directors and perhaps deputy directors is less surprising, the demographics of current research program leaders and associate directors exposes a substantial lack of diversity in the traditional cancer center senior leadership pipeline. Sole reliance on the cohort of current center leaders and leadership pipeline is unlikely to produce the diversity in cancer center leadership needed to facilitate the ability of those centers to address the needs of the diverse populations they serve. Informed by these data, this commentary describes some best practices to build a pipeline of emerging leaders who are representative of the diverse populations served by these institutions and who are well positioned to succeed.

IV vitamin C with chemotherapy for cisplatin ineligible bladder cancer patients (CI-MIBC) first-stage analysis NCT04046094

e16540

Background: Neo-adjuvant cisplatin-based chemotherapy (NAC) is considered standard of care for patients with locally advanced disease. However, ̃40% of patients are cisplatin ineligible (CI) due to renal insufficiency, hearing loss or poor performance status. Gemcitabine and carboplatin (GCa) has limited success in this setting. Patients usually proceed directly to cystectomy without realizing the potential survival benefit afforded by NAC. Intravenous ascorbate (vitamin C) administration (IVC) has been shown to improve the efficacy of carboplatin and gemcitabine-based therapy in other models. This single-arm, Simon 2-stage, window of opportunity trial included IVC with single cycle GCa to evaluate pathologic downstaging. We report on the interim first stage analysis of 12 patients. Methods: Patients with newly diagnosed CI-MIBC were enrolled and received single cycle GCa and IVC titrated to peak plasma concentration of 350 to 400 mg/dL (̃20 mM) for 21 days followed by cystectomy at 4-6 weeks from initiation of treatment. The primary outcome is pathological stage at cystectomy. Patients are then followed per NCCN guidelines with standard of care bloodwork, physical exam and imaging studies until progression and/or death. QOL is being evaluated by Functional Assessment of Cancer Therapy-Bladder (FACT-Bl). Results: All 12 patients completed GCa/IVC with 11 having had a cystectomy and 1 pending surgery. Pathological downstaging (yp < T2) was noted in 4 patients with 3 CRs (ypT0N0Mx) and 1 with residual ypTisN0Mx only. Of note, 1 CR was seen in a patient with locally advanced plasmacytoid variant. Participants tolerated treatment well with minimal treatment related AE/SAEs. Conclusions: Interim analysis of GCa-IVC NAC shows good tolerability with > 36% rate of downstaging. Of those with a pathological response, 75% achieved a CR. Continuation criteria has been met for stage 2. FACT-BI analysis and clinical follow up is ongoing and will be reported at study completion. Clinical trial information: NCT04046094.

Bringing experimental therapeutics clinical trials network (ETCTN) to underrepresented population

6542

Background: Access to health care including clinical trials (CT) leading to paradigm-changing cancer treatments are critical for high quality cancer care and equity in society. In this report, we highlight methods in accruing to ETCTN wherein underrepresented rural, low-income, and racial minorities comprise >50% of enrollment. Methods: University of Kansas Cancer Center (KUCC) is one of eight National Cancer Institute (NCI) designated cancer centers awarded CATCH-UP.2020 (CATCH-UP), a congressionally mandated P30 supplement to enhance access for minority/underserved populations to ETCTN precision medicine CT. KUCC catchment area is 23% rural by Rural Urban Continuum Codes (RUCC); almost 90 % of counties are designated primary care HPSA’s (Health Professional Shortage Areas). KUCC Early Phase and Masonic Cancer Alliance (rural outreach network) partnered to operationalize CATCH-UP. We engaged disease-focused champion investigators in disease working groups and MCA physicians who selected scientifically sound CT that fit catchment area needs. Patient and Investigator Voices Organizing Together, a patient research advocacy group provided practical feedback. MCA navigator coordinated recruitment. Telehealth was used for rural patients that would have a significant distance to travel just to be screened. Results: CATCH-UP was initiated in September 2020. Twenty-eight CT were activated, many in community sites. Average activation time was 81 days. Delays were mainly from CT amendments. KUCC enrolled the first patient in the CATCH-UP program. In 6 months, we met accrual requirements (24/year, 50% minorities). During first year, we enrolled 47 (>50% minorities), an increase of 680% from our average accrual of 6/year (>50% minorities) in ETCTN through Early Drug Development Opportunity Program (2016-2020). To date, we have enrolled 61, 54% from rural, HPSA, race and other minorities. Although the proportion of minorities did not change but remained high, this funding allowed us to substantially increase the number of patients from a catchment area with high proportion of geographically and socioeconomically underserved minorities given access to early phase CT through ETCTN. Conclusions: Amid COVID-19 pandemic, the NCI CATCH-UP program and methods we used allowed access to novel therapies for rural, medically underserved, and other minority groups. Funded by NIH: 3P30CA168524-09S2.

Phase 1B/2A safety, pharmacokinetics, and pharmacodynamics study of fosciclopirox alone and in combination with cytarabine in patients with relapsed/refractory acute myeloid leukemia

TPS7069

Background: Fosciclopirox (F) is a γ-secretase inhibitor being developed for the treatment of acute myeloid leukemia (AML). Following intravenous (IV) administration, F is rapidly and completely metabolized to its active metabolite, ciclopirox (CPX). CPX binds to γ-secretase complex proteins Presenilin 1 and Nicastrin, which are essential for Notch activation. In HL60 cells, CPX inhibits Notch 1 and Notch 2 expression, reduces levels of γ-secretase complex proteins Presenilin 1 and Nicastrin, and decreases expression of the downstream Notch target gene Hes-1. Utilizing Notable Labs predictive precision medicine platform, bone marrow (BM) and peripheral blood (PB) samples obtained from 10 AML patients treated with CPX demonstrated significant blast count reductions. Methods: Study CPX-POM-003 (NCT04956042) is an open-label Phase 1B/2A, trial designed to characterize the efficacy, safety, and PK/PD of F alone and in combination with cytarabine (ara-C) in patients with relapsed/refractory AML (R/R AML). Eligible patients must be 18 years of age or older with relapsed AML after complete remission or with primary refractory AML refractory to at least two cycles of induction therapy. There will be up to three cohorts of patients, approximately 42 R/R AML patients, evaluated. If disease response to F alone (Cohort 1a) is observed in at least 4 of 14 patients, an additional 14 patients will be enrolled in Cohort 1b. If disease response is not observed following F alone, the study may be terminated or a second cohort, Cohort 2a, may be initiated to evaluate the combination of F + ara-C. If disease response to F + ara-C is observed in at least 4 of 14 patients, an additional 14 patients will be enrolled in Cohort 2b. If response to F + ara-C is not observed in at least 4 of 14 patients, the study will be stopped for futility. F is being administered as 900 mg/m2 once daily as a 20-minute IV infusion on Days 1 to 5 of each 21-day treatment cycle. Ara-C is administered as 1 gm/m2 once daily on Days 1 to 5 of each cycle. BM and PB samples are collected prior to and during Cycles 1 (C1) and 2 (C2) for disease response assessment and blast count determination. Additional BM and PB samples are obtained after every two cycles beyond C2 for patients continuing treatment. Disease response is determined based on Döhner et al, Blood 2017;129(4)424-447. Next Generation Sequencing (NGS) profiles will be determined prior to and at the end of C1, and thereafter as clinically indicated. Immunohistochemistry will be performed on BM samples to elucidate drug mechanism. Ex vivo Drug Sensitivity Screening (DSS) will be performed on BM and PB samples obtained prior to treatment as well as on C1 Days 8 and 21. The steady-state plasma pharmacokinetics of F are being characterized during C1. Enrollment began in October 2022 with four patients enrolled to date. Clinical trial information: NCT04956042.

Loss of REST in breast cancer promotes tumor progression through estrogen sensitization, MMP24 and CEMIP overexpression

BACKGROUND

Breast cancer is the most common malignancy in women, and is both pathologically and genetically heterogeneous, making early detection and treatment difficult. A subset of breast cancers express normal levels of REST (repressor element 1 silencing transcription factor) mRNA but lack functional REST protein. Loss of REST function is seen in ~ 20% of breast cancers and is associated with a more aggressive phenotype and poor prognosis. Despite the frequent loss of REST, little is known about the role of REST in the molecular pathogenesis of breast cancer.

METHODS

TCGA data was analyzed for the expression of REST target genes in breast cancer patient samples. We then utilized gene knockdown in MCF-7 cells in the presence or absence of steroid hormones estrogen and/ progesterone followed by RNA sequencing, as well as chromatin immunoprecipitation and PCR in an attempt to understand the tumor suppressor role of REST in breast cancer.

RESULTS

We show that REST directly regulates CEMIP (cell migration-inducing and hyaluronan-binding protein, KIAA1199) and MMP24 (matrix metallopeptidase 24), genes known to have roles in invasion and metastasis. REST knockdown in breast cancer cells leads to significant upregulation of CEMIP and MMP24. In addition, we found REST binds to RE-1 sites (repressor element-1) within the genes and influences their transcription. Furthermore, we found that the estrogen receptor (ESR1) signaling pathway is activated in the absence of REST, regardless of hormone treatment.

CONCLUSIONS

We demonstrate a critical role for the loss of REST in aggressive breast cancer pathogenesis and provide evidence for REST as an important diagnostic marker for personalized treatment plans.

Abstract P5-04-05: Loss of REST in breast cancer promotes tumor progression through estrogen sensitization, MMP24 and CEMIP overexpression

Breast cancer is the most common malignancy in women and is the second leading cause of cancer-related deaths. Breast cancer is both pathologically and genetically heterogeneous, making early detection and treatment difficult. A subset of breast cancers expresses normal levels of REST (Repressor Element 1 Silencing Transcription factor) mRNA but lacks functional REST protein. Loss of REST function is seen in ~20% of breast cancers and is associated with a more aggressive phenotype and poor prognosis. Despite the frequent loss of REST, little is known about the role of REST in the molecular pathogenesis of breast cancer. TCGA data was analyzed for the expression of REST and its target genes in breast cancer patient samples. MCF7, an estrogen and progesterone receptor positive breast cancer cell line, and MDA-MB-231, a triple-negative breast cancer cell line were used for in vitro studies to understand the function of REST. To evaluate the role of REST in the regulation of hormone receptor pathways, RNA sequencing was carried out on total RNA from MCF7 cells after siRNA knockdown of REST followed by treatment of hormones estrogen and progesterone. Chromatin Immunoprecipitation and PCR were performed on REST knockdown cells to evaluate gene regulation by REST and understand its tumor suppressor role in breast cancer. We show that REST directly regulates CEMIP (Cell Migration-Inducing and Hyaluronan-Binding Protein, KIAA1199) and MMP24 (Matrix Metallopeptidase 24), genes known to have roles in invasion and metastasis. REST knockdown in breast cancer cell lines leads to significant upregulation of CEMIP and MMP24. In addition, we found that REST binds to RE-1 sites (Repressor Element-1) within the genes and influences their transcriptional regulation. Aberrant expression of CEMIP and MMP24 results in CD44 dependent cell signaling that promotes cell proliferation and survival. We also found that the estrogen receptor signaling pathway is activated in the absence of REST regardless of hormone treatment. Our studies show that REST plays a significant role in altering the estrogen signaling pathway in hormone-sensitive breast cancers. REST transcriptionally regulates genes known to affect cell invasion and metastasis. Importantly, we demonstrate that loss of REST promotes aggressive breast cancer and see REST as an attractive therapeutic target.

Citation Format: Aditya M. Vargheese, Ashley S. Cloud, Sumedha Gunewardena, Raeann M. Shimak, Sornakala Ganeshkumar, Easwari Kumaraswamy, Roy A. Jensen, Vargheese M. Chennathukuzhi. Loss of REST in breast cancer promotes tumor progression through estrogen sensitization, MMP24 and CEMIP overexpression [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-04-05.

OPTIK: a database for understanding catchment areas to guide mobilization of cancer center assets

An increasingly diversified demographic landscape in rural and urban America warrants the attention of The University of Kansas Cancer Center (KU Cancer Center) researchers, clinicians, outreach staff and administrators as the institution assesses ways to reach its expansive, bi-state catchment area. Within the counties of the KU Cancer Center catchment area, patient level and public health data are available and categorized by varying geographic regional boundaries. Multiple data sources and different data collection processes complicate summarizing catchment area data. A curated data warehouse that retrieves and structures the data, with a common denominator, can support meaningful use of the data in a standard and consistent format. The KU Cancer Center built a data warehouse to Organize and Prioritize Trends to Inform KU Cancer Center (OPTIK), which functions to streamline the process of synthesizing data regarding Kansas and Missouri demographics, cancer risk factors and incidence and mortality rates. OPTIK standardizes these diverse data sources to enable analyses of the cancer burden at local, regional and national levels while upholding a strict standard of patient privacy. The OPTIK database enables researchers to use available data and create heat maps and other visualizations to aid in funding proposals, presentations and research activities. Furthermore, using knowledge provided by OPTIK, the KU Cancer Center is able to prioritize action items for research and outreach and more effectively communicate the impact of those efforts.

Honokiol Affects Stem Cell Viability by Suppressing Oncogenic YAP1 Function to Inhibit Colon Tumorigenesis

Honokiol (HNK) is a biphenolic compound that has been used in traditional medicine for treating various ailments, including cancers. In this study, we determined the effect of HNK on colon cancer cells in culture and in a colitis-associated cancer model. HNK treatment inhibited proliferation and colony formation while inducing apoptosis. In addition, HNK suppressed colonosphere formation. Molecular docking suggests that HNK interacts with reserve stem cell marker protein DCLK1, with a binding energy of -7.0 Kcal/mol. In vitro kinase assays demonstrated that HNK suppressed the DCLK1 kinase activity. HNK also suppressed the expression of additional cancer stem cell marker proteins LGR5 and CD44. The Hippo signaling pathway is active in intestinal stem cells. In the canonical pathway, YAP1 is phosphorylated at Ser127 by upstream Mst1/2 and Lats1/2. This results in the sequestration of YAP1 in the cytoplasm, thereby not allowing YAP1 to translocate to the nucleus and interact with TEAD1-4 transcription factors to induce gene expression. However, HNK suppressed Ser127 phosphorylation in YAP1, but the protein remains sequestered in the cytoplasm. We further determined that this occurs by YAP1 interacting with PUMA. To determine if this also occurs in vivo, we performed studies in an AOM/DSS induced colitis-associated cancer model. HNK administered by oral gavage at a dose of 5mg/kg bw for 24 weeks demonstrated a significant reduction in the expression of YAP1 and TEAD1 and in the stem marker proteins. Together, these data suggest that HNK prevents colon tumorigenesis in part by inducing PUMA-YAP1 interaction and cytoplasmic sequestration, thereby suppressing the oncogenic YAP1 activity.

Preclinical Evaluation of Gilteritinib on NPM1-ALK-Driven Anaplastic Large Cell Lymphoma Cells

Anaplastic large cell lymphoma (ALCL) is an aggressive type of non-Hodgkin lymphoma. More than three-fourths of anaplastic lymphoma kinase (ALK)-positive ALCL cases express the nucleophosmin 1 (NPM1)-ALK fusion gene as a result of t(2;5) chromosomal translocation. The homodimerization of NPM1-ALK fusion protein mediates constitutive activation of the chimeric tyrosine kinase activity and downstream signaling pathways responsible for lymphoma cell proliferation and survival. Gilteritinib is a tyrosine kinase inhibitor recently approved by the FDA for the treatment of FMS-like tyrosine kinase mutation-positive acute myeloid leukemia. In this study, we demonstrate for the first time gilteritinib-mediated growth inhibitory effects on NPM1-ALK-driven ALCL cells. We utilized a total of five ALCL model cell lines, including both human and murine. Gilteritinib treatment inhibits NPM1-ALK fusion kinase phosphorylation and downstream signaling, resulting in induced apoptosis. Gilteritinib-mediated apoptosis was associated with caspase 3/9, PARP cleavage, the increased expression of proapoptotic protein BAD, and decreased expression of antiapoptotic proteins, survivin and MCL-1. We also found downregulation of fusion kinase activity resulted in decreased c-Myc protein levels. Furthermore, cell-cycle analysis indicated gilteritinib induced G₀-G₁-phase cell-cycle arrest and reduced CD30 expression. In summary, our preclinical studies explored the novel therapeutic potential of gilteritinib in the treatment of ALCL cells expressing NPM1-ALK and potentially in other ALK or ALK fusion-driven hematologic or solid malignancies. IMPLICATIONS: Our preclinical results explore the use of gilteritinib for the treatment of NPM1-ALK-driven ALCL cells and pave a path for developing future clinical trials. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/5/913/F1.large.jpg.

Randomized Phase II Trial of Anthracycline-free and Anthracycline-containing Neoadjuvant Carboplatin Chemotherapy Regimens in Stage I-III Triple-negative Breast Cancer (NeoSTOP)

PURPOSE

Addition of carboplatin (Cb) to anthracycline chemotherapy improves pathologic complete response (pCR), and carboplatin plus taxane regimens also yield encouraging pCR rates in triple-negative breast cancer (TNBC). Aim of the NeoSTOP multisite randomized phase II trial was to assess efficacy of anthracycline-free and anthracycline-containing neoadjuvant carboplatin regimens.

PATIENTS AND METHODS

Patients aged ≥18 years with stage I-III TNBC were randomized (1:1) to receive either paclitaxel (P) weekly × 12 plus carboplatin AUC6 every 21 days × 4 followed by doxorubicin/cyclophosphamide (AC) every 14 days × 4 (CbP → AC, arm A), or carboplatin AUC6 + docetaxel (D) every 21 days × 6 (CbD, arm B). Stromal tumor-infiltrating lymphocytes (sTIL) were assessed. Primary endpoint was pCR in breast and axilla. Other endpoints included residual cancer burden (RCB), toxicity, cost, and event-free (EFS) and overall survival (OS).

RESULTS

One hundred patients were randomized; arm A (n = 48) or arm B (n = 52). pCR was 54% [95% confidence interval (CI), 40%-69%] in arm A and 54% (95% CI, 40%-68%) in arm B. RCB 0+I rate was 67% in both arms. Median sTIL density was numerically higher in those with pCR compared with those with residual disease (20% vs. 5%; P = 0.25). At median follow-up of 38 months, EFS and OS were similar in the two arms. Grade 3/4 adverse events were more common in arm A compared with arm B, with the most notable differences in neutropenia (60% vs. 8%; P < 0.001) and febrile neutropenia (19% vs. 0%; P < 0.001). There was one treatment-related death (arm A) due to acute leukemia. Mean treatment cost was lower for arm B compared with arm A (P = 0.02).

CONCLUSIONS

The two-drug CbD regimen yielded pCR, RCB 0+I, and survival rates similar to the four-drug regimen of CbP → AC, but with a more favorable toxicity profile and lower treatment-associated cost.

Abstract 6405: Fosciclopirox suppresses growth of high-grade urothelial cancer by targeting Notch signaling

Ciclopirox (CPX) is a FDA-approved topical antifungal agent that has demonstrated preclinical anticancer activity in solid and hematologic malignancies. It's clinical utility as an anticancer agent, however, is limited by poor oral bioavailability, gastrointestinal toxicity, and poor water solubility. Fosciclopirox, the phosphoryloxymethyl ester of CPX (Ciclopirox Prodrug, CPX-POM), is rapidly and completely metabolized to CPX, the active metabolite, which subsequently undergoes renal elimination resulting in urine concentrations of CPX that exceed in vitro IC50's several-fold. We characterized the activity of CPX-POM and its major metabolites in vitro utilizing authenticated human T24, HT-1376, and UM-UC-3 high-grade urothelial cancer cell lines. CPX inhibited cell proliferation, clonogenicity, and spheroid formation, and increased cell cycle arrest at S and G0/G1 phases. Mechanistically, CPX suppressed activation of Notch signaling, which was partially rescued by ectopic expression of the intracellular domain of Notch1. Molecular modeling and cellular thermal shift assays demonstrated CPX binding to γ-secretase complex proteins Presenilin1 and Nicastrin, which are essential for Notch activation. Interrogation of The Cancer Genome Atlas (TCGA) database demonstrated that both proteins were upregulated in bladder tumor tissue, and that higher levels of Presenilin1 and Nicastrin were significantly associated with lower overall survival in muscle invasive bladder cancer (MIBC) patients. To establish in vivo preclinical proof of principle, we tested fosciclopirox in the validated N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) mouse bladder cancer model in two separate studies. Intraperitoneal (IP) administration of CPX-POM once daily for four weeks at doses ranging from 25 to 200 mg/kg significantly decreased bladder weight and resulted in a migration to lower stage tumors in CPX-POM treated animals compared to untreated animals. This was coupled with a reduction in proliferation index, as well as reductions in Presenilin1 and Hey1 expression in bladder tumor tissues in CPX-POM treated animals. A similar anti-tumor response was observed following once daily versus three times weekly IP CPX-POM in this chemical carcinogen mouse model of bladder cancer. The safety, dose tolerance, pharmacokinetics and pharmacodynamics of intravenous (IV) CPX-POM were characterized in a US multi-center, First-in-Human, Phase 1, open-label, dose escalation study (NCT03348514). Eight cohorts of 19 patients received IV CPX-POM doses ranging from 30 to 1200 mg/m2 for as many as six 21-day treatment cycles. Adequate systemic and urinary tract CPX exposures were achieved at the maximum tolerated dose of 900 mg/m2 with evidence of Notch inhibition. An expansion cohort study in 12 cisplatin-ineligible MIBC patients receiving two treatment cycles of CPX-POM prior to radical cystectomy (RC) is underway. Evidence of pharmacologic activity is being characterized in bladder tumor tissues obtained at RC.

Citation Format: Scott James Weir, Prasad Dandawate, Prabhu Ramamoorthy, Parthasarathy Ranjarajan, Robyn Wood, Amanda Brinker, Benjamin Woolbright, Mehmet Tanol, Tammy Ham, William McCulloch, Michael Dalton, Michael J. Baltezor, Roy A. Jensen, John A. Taylor, Shrikant Anant. Fosciclopirox suppresses growth of high-grade urothelial cancer by targeting Notch signaling [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6405.

Abstract 4703: Role of REST in the regulation of MMP24 and estrogen sensitivity in breast cancer

Breast cancer, the most common malignancy in women, is very difficult to detect and treat due to its heterogeneity. An important subset of breast cancers, Luminal or ER/PR positive tumors, lack REST (repressor element 1 silencing transcription factor) protein but not its mRNA. REST is a tumor suppressor and is known to play a role in regulating neurodegenerative diseases such as Alzheimer's. The loss of REST leads to the dysregulation of its target genes, many of which are involved in tumorigenesis. About 20% of breast cancers show loss of REST expression, yet little to nothing is currently known about the role REST plays in tumor growth. We hypothesized that the loss of REST promotes breast cancer growth by altering cell signaling. Our results show that knockdown of REST in MCF7 cells (ER/PR positive) causes similar gene dysregulation as seen in aggressive forms of breast cancers. Also, Ingenuity Pathway Analysis (IPA®) of our RNA sequencing results showed that REST knockdown leads to significant increase in estrogen receptor signaling in MCF7 cells. Upregulation of estrogen receptor expression has been associated with tumor progression. In addition, REST knockdown led to significant increases in the expression of MMP24 (&gt;20-fold, p&lt;10−85), a matrix modifying enzyme which could play a role in tumor metastasis, as well as KCNK3 (19-fold, p&lt;10−40), a biomarker associated with poor patient survival. Thus, the poor survival of patients with RESTless breast cancers may be related to the activation of its target genes and elevated estrogen receptor signaling. Furthermore, these patients may respond differently to estrogen receptor antagonists compared to those with REST positive breast cancers. Our results will help with the future development of individualized therapies for breast cancer.

Citation Format: Aditya M. Vargheese, Ashley Cloud, Sumedha Gunewardena, Raeann Shimak, Easwari Kumaraswamy, Roy A. Jensen, Vargheese M. Chennathukuzhi. Role of REST in the regulation of MMP24 and estrogen sensitivity in breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4703.

Diphenylbutylpiperidine Antipsychotic Drugs Inhibit Prolactin Receptor Signaling to Reduce Growth of Pancreatic Ductal Adenocarcinoma in Mice

BACKGROUND & AIMS

Prolactin (PRL) signaling is up-regulated in hormone-responsive cancers. The PRL receptor (PRLR) is a class I cytokine receptor that signals via the Janus kinase (JAK)-signal transducer and activator of transcription and mitogen-activated protein kinase pathways to regulate cell proliferation, migration, stem cell features, and apoptosis. Patients with pancreatic ductal adenocarcinoma (PDAC) have high plasma levels of PRL. We investigated whether PRLR signaling contributes to the growth of pancreatic tumors in mice.

METHODS

We used immunohistochemical analyses to compare levels of PRL and PRLR in multitumor tissue microarrays. We used structure-based virtual screening and fragment-based drug discovery to identify compounds likely to bind PRLR and interfere with its signaling. Human pancreatic cell lines (AsPC-1, BxPC-3, Panc-1, and MiaPaCa-2), with or without knockdown of PRLR (clustered regularly interspaced short palindromic repeats or small hairpin RNA), were incubated with PRL or penfluridol and analyzed in proliferation and spheroid formation. C57BL/6 mice were given injections of UNKC-6141 cells, with or without knockdown of PRLR, into pancreas, and tumor development was monitored for 4 weeks, with some mice receiving penfluridol treatment for 21 days. Human pancreatic tumor tissues were implanted into interscapular fat pads of NSG mice, and mice were given injections of penfluridol daily for 28 days. Nude mice were given injections of Panc-1 cells, xenograft tumors were grown for 2 weeks, and mice were then given intraperitoneal penfluridol for 35 days. Tumors were collected from mice and analyzed by histology, immunohistochemistry, and immunoblots.

RESULTS

Levels of PRLR were increased in PDAC compared with nontumor pancreatic tissues. Incubation of pancreatic cell lines with PRL activated signaling via JAK2-signal transducer and activator of transcription 3 and extracellular signal-regulated kinase, as well as formation of pancospheres and cell migration; these activities were not observed in cells with PRLR knockdown. Pancreatic cancer cells with PRLR knockdown formed significantly smaller tumors in mice. We identified several diphenylbutylpiperidine-class antipsychotic drugs as agents that decreased PRL-induced JAK2 signaling; incubation of pancreatic cancer cells with these compounds reduced their proliferation and formation of panco spheres. Injections of 1 of these compounds, penfluridol, slowed the growth of xenograft tumors in the different mouse models, reducing proliferation and inducing autophagy of the tumor cells.

CONCLUSIONS

Levels of PRLR are increased in PDAC, and exposure to PRL increases proliferation and migration of pancreatic cancer cells. Antipsychotic drugs, such as penfluridol, block PRL signaling in pancreatic cancer cells to reduce their proliferation, induce autophagy, and slow the growth of xenograft tumors in mice. These drugs might be tested in patients with PDAC.

Utilization of Technology to Improve Efficiency in Investigational Drug Management Processes

Background: Background: An investigational pharmacy is responsible for all tasks related to receiving, storing, and dispensing of any investigational drugs. Traditional methods of inventory and protocol tracking on paper binders are very tedious and could be error-prone. Objective: To evaluate the utilization of the IDS to efficiently manage the inventory within an investigational Pharmacy. We hypothesize that the IDS will reduce the drug processing time. Methods: Our pharmacy tracked the drug processing time before and after using the IDS including the receiving, dispensing, and inventory. As part of the receiving the study drug pharmacists tracked the time it took a pharmacist to complete the tasks of logging the study drug before and after the implementation of the IDS system. In addition, the pharmacy also timed the process for drug dispensing and a full investigational drug inventory check. Wilcoxon signed-rank test was used to compare the difference in the meantime of total processing before and after the IDS. Results: Utilization of the IDS system showed significant reduction in processing time, and improvement of efficiency in inventory management. Additionally, the usability survey of the IDS demonstrated that the IDS system helped pharmacists capture data consistently across every clinical trial. Conclusion: Our results demonstrates how technology helps pharmacists to focus on their actual day to day medication-related tasks rather than worrying about other operational aspects. Informatics team continues to further enhance the features such as monitor portal, and features related to finance - generation of invoices, billing reconciliation, etc.

Window of opportunity trial to characterize the safety, pharmacokinetics, and pharmacodynamics of fosciclopirox (CPX-POM) in cisplatin-ineligible muscle invasive bladder cancer patients

TPS604

Background: Fosciclopirox (Ciclopirox Prodrug, CPX-POM) is being developed for the treatment of non-muscle invasive and muscle invasive (MIBC) bladder cancer. CPX-POM selectively delivers its active metabolite, ciclopirox (CPX), to the entire urinary tract following systemic administration. In a validated, chemical carcinogen mouse model of bladder cancer, CPX-POM treatment results in significant decreases in bladder weight, a clear migration to lower stage tumors, dose-dependent reductions in Ki67 and PCNA staining, and inhibition of Notch 1 and Wnt signaling. The safety, dose tolerance, pharmacokinetics and pharmacodynamics of IV CPX-POM have recently been characterized in 19 patients with advanced solid tumors (CPX-POM-001, NCT03348514). The safety and dose tolerance of IV CPX-POM was characterized across a dose range of 30 to 1200 mg/m2. The CPX-POM Recommended Phase 2 Dose (PR2D) of 900 mg/m2 administered IV over 20 minutes on Days 1-5 every 21 days was selected. Methods: Twelve cisplatin ineligible MIBC patients (Stage >T2, NO-N1, M0), scheduled for radical cystectomy (RC) will be enrolled in this window of opportunity study. Patients will receive two 21-day treatment cycles followed by RC within 14 days of completion of the second cycle. Safety and tolerability assessments will be made based on observed adverse and serious adverse events, physical examination, vital signs, electrocardiogram, clinical laboratory tests, and concomitant medications. Assessment of complete and partial pathologic response will be determined at RC. Ki67, Notch and Wnt signaling, and CD8+ lymphocyte tumor infiltration will be determined by immunohistochemistry. An unbiased approach to characterizing CPX-POM mechanisms of action will also be employed using RNAseq and ChIPseq. Serial blood (plasma) and complete urine specimens will be collected on Days 5-6 of Cycle 1 for determination of drug and metabolite concentrations by LC-MS/MS. Plasma and urine steady-state pharmacokinetics of CPX-POM, CPX and ciclopirox glucuronide will be characterized. Urine ß-glucuronidase activity is also being determined by ELISA. Clinical trial information: NCT03348514.

Safety, dose tolerance, pharmacokinetics, and pharmacodynamics of fosciclopirox (CPX-POM) in patients with advanced solid tumors

518

Background: Fosciclopirox (CPX-POM) is being developed for the treatment of non-muscle invasive and muscle invasive bladder cancer. CPX-POM selectively delivers its active metabolite, ciclopirox (CPX), to the entire urinary tract following systemic administration. In a chemical carcinogen mouse model of bladder cancer, CPX-POM treatment resulted in significant decreases in bladder weight, migration to lower stage tumors, inhibition of cell proliferation as well as Notch 1 and Wnt signaling pathways. Methods: Study CPX-POM-001 (NCT03348514) is US multi-site, Phase I, open-label, dose escalation study characterizing the safety, dose tolerance, pharmacokinetics (PK) and pharmacodynamics of IV CPX-POM in advanced solid tumor patients. The PK of CPX-POM, CPX and ciclopirox glucuronide (CPX-G), were characterized in plasma and urine. Circulating biomarkers of Wnt and Notch, IL-6, IL-8 and VEGF were determined. Results: Nineteen patients were enrolled in the study. The starting dose of 30 mg/m2 was administered once daily on Days 1-5 of each 21-day treatment cycle. Doses were escalated to 1200 mg/m2. The MTD was determined to be 900 mg/m2. Overall, the number of treatment-related AE's tended to increase in frequency with dose, nausea and vomiting being the most common. Grade 3 confusion was observed in the 1200 mg/m2 cohort. Four AE's of Grade 1 confusion at 600 and 900 mg/m2. There was no evidence of QTc prolongation or other ECG abnormality. One patient in the 240 mg/m2 dose cohort, with a diagnosis of indolent primary fallopian tube tumor, achieved a partial response per RECIST 1.1. Metabolism of CPX-POM was rapid and complete. The clearance of CPX was dose proportional and time-independent. At MTD, steady-state 24-hour urine CPX concentrations of 215 µM were achieved. Evidence of Notch and Wnt inhibition was observed. Conclusions: IV CPX-POM was well tolerated with treatment-related AEs primarily CNS-related. At MTD, systemic and urinary CPX exposures exceeding in vitro IC50 values by several-fold. The 900 mg/m2 dose is currently being evaluated in an expansion cohort study in cisplatin-ineligible muscle invasive bladder cancer patients scheduled for cystectomy. Clinical trial information: NCT03348514.

Cucurbitacin B and I inhibits colon cancer growth by targeting the Notch signaling pathway

Cancer stem cells (CSCs) have the ability to self-renew and induce drug resistance and recurrence in colorectal cancer (CRC). As current chemotherapy doesn’t eliminate CSCs completely, there is a need to identify novel agents to target them. We investigated the effects of cucurbitacin B (C-B) or I (C-I), a natural compound that exists in edible plants (bitter melons, cucumbers, pumpkins and zucchini), against CRC. C-B or C-I inhibited proliferation, clonogenicity, induced G₂/M cell-cycle arrest and caspase-mediated-apoptosis of CRC cells. C-B or C-I suppressed colonosphere formation and inhibited expression of CD44, DCLK1 and LGR5. These compounds inhibited notch signaling by reducing the expression of Notch 1–4 receptors, their ligands (Jagged 1-2, DLL1,3,4), γ-secretase complex proteins (Presenilin 1, Nicastrin), and downstream target Hes-1. Molecular docking showed that C-B or C-I binds to the ankyrin domain of Notch receptor, which was confirmed using the cellular thermal shift assay. Finally, C-B or C-I inhibited tumor xenograft growth in nude mice and decreased the expression of CSC-markers and notch signaling proteins in tumor tissues. Together, our study suggests that C-B and C-I inhibit colon cancer growth by inhibiting Notch signaling pathway.

Optimizing Retrieval of Biospecimens Using the Curated Cancer Clinical Outcomes Database (C3OD)

To fully support their role in translational and personalized medicine, biorepositories and biobanks must continue to advance the annotation of their biospecimens with robust clinical and laboratory data. Translational research and personalized medicine require well-documented and up-to-date information, but the infrastructure used to support biorepositories and biobanks can easily be out of sync with the host institution. To assist researchers and provide them with accurate pathological, epidemiological, and bio-molecular data, the Biospecimen Repository Core Facility (BRCF) at the University of Kansas Medical Center (KUMC) merges data from medical records, the tumor registry, and pathology reports using the Curated Cancer Clinical Outcomes Database (C3OD). In this report, we describe the utilization of C3OD to optimally retrieve and dispense biospecimen samples using these 3 data sources and demonstrate how C3OD greatly increases the efficiency of obtaining biospecimen samples for the researchers.

The Histone Demethylase KDM3A, Increased in Human Pancreatic Tumors, Regulates Expression of DCLK1 and Promotes Tumorigenesis in Mice

BACKGROUND & AIMS

The histone lysine demethylase 3A (KDM3A) demethylates H3K9me1 and H3K9Me2 to increase gene transcription and is upregulated in tumors, including pancreatic tumors. We investigated its activities in pancreatic cancer cell lines and its regulation of the gene encoding doublecortin calmodulin-like kinase 1 (DCLK1), a marker of cancer stem cells.

METHODS

We knocked down KDM3A in MiaPaCa-2 and S2-007 pancreatic cancer cell lines and overexpressed KDM3A in HPNE cells (human noncancerous pancreatic ductal cell line); we evaluated cell migration, invasion, and spheroid formation under hypoxic and normoxic conditions. Nude mice were given orthotopic injections of S2-007 cells, with or without (control) knockdown of KDM3A, and HPNE cells, with or without (control) overexpression of KDM3A; tumor growth was assessed. We analyzed pancreatic tumor tissues from mice and pancreatic cancer cell lines by immunohistochemistry and immunoblotting. We performed RNA-sequencing analysis of MiaPaCa-2 and S2-007 cells with knockdown of KDM3A and evaluated localization of DCLK1 and KDM3A by immunofluorescence. We analyzed the cancer genome atlas for levels of KDM3A and DCLK1 messenger RNA in human pancreatic ductal adenocarcinoma (PDAC) tissues and association with patient survival time.

RESULTS

Levels of KDM3A were increased in human pancreatic tumor tissues and cell lines, compared with adjacent nontumor pancreatic tissues, such as islet and acinar cells. Knockdown of KDM3A in S2-007 cells significantly reduced colony formation, invasion, migration, and spheroid formation, compared with control cells, and slowed growth of orthotopic tumors in mice. We identified KDM3A-binding sites in the DCLK1 promoter; S2-007 cells with knockdown of KDM3A had reduced levels of DCLK1. HPNE cells that overexpressed KDM3A formed foci and spheres in culture and formed tumors and metastases in mice, whereas control HPNE cells did not. Hypoxia induced sphere formation and increased levels of KDM3A in S2-007 cells and in HPNE cells that overexpressed DCLK1, but not control HPNE cells. Levels of KDM3A and DCLK1 messenger RNA were higher in human PDAC than nontumor pancreatic tissues and correlated with shorter survival times of patients.

CONCLUSIONS

We found human PDAC samples and pancreatic cancer cell lines to overexpress KDM3A. KDM3A increases expression of DCLK1, and levels of both proteins are increased in human PDAC samples. Knockdown of KDM3A in pancreatic cancer cell lines reduced their invasive and sphere-forming activities in culture and formation of orthotopic tumors in mice. Hypoxia increased expression of KDM3A in pancreatic cancer cells. Strategies to disrupt this pathway might be developed for treatment of pancreatic cancer.

Preclinical Pharmacokinetics of Fosciclopirox, a Novel Treatment of Urothelial Cancers, in Rats and Dogs

Pharmacokinetic studies in rats and dogs were performed to characterize the in vivo performance of a novel prodrug, fosciclopirox. Ciclopirox olamine (CPX-O) is a marketed topical antifungal agent with demonstrated in vitro and in vivo preclinical anticancer activity in several solid tumor and hematologic malignancies. The oral route of administration for CPX-O is not feasible due to low bioavailability and dose-limiting gastrointestinal toxicities. To enable parenteral administration, the phosphoryl-oxymethyl ester of ciclopirox (CPX), fosciclopirox (CPX-POM), was synthesized and formulated as an injectable drug product. In rats and dogs, intravenous CPX-POM is rapidly and completely metabolized to its active metabolite, CPX. The bioavailability of the active metabolite is complete following CPX-POM administration. CPX and its inactive metabolite, ciclopirox glucuronide (CPX-G), are excreted in urine, resulting in delivery of drug to the entire urinary tract. The absolute bioavailability of CPX following subcutaneous administration of CPX-POM is excellent in rats and dogs, demonstrating the feasibility of this route of administration. These studies confirmed the oral bioavailability of CPX-O is quite low in rats and dogs compared with intravenous CPX-POM. Given its broad-spectrum anticancer activity in several solid tumor and hematologic cancers and renal elimination, CPX-POM is being developed for the treatment of urothelial cancer. The safety, dose tolerance, pharmacokinetics, and pharmacodynamics of intravenous CPX-POM are currently being characterized in a United States multicenter first-in-human Phase 1 clinical trial in patients with advanced solid tumors (NCT03348514).

Results of randomized phase II trial of neoadjuvant carboplatin plus docetaxel or carboplatin plus paclitaxel followed by AC in stage I-III triple-negative breast cancer (NCT02413320)

516

Background: Addition of neoadjuvant carboplatin (Cb) to paclitaxel (T) followed by doxorubicin + cyclophosphamide (AC) improves pathologic complete response (pCR) rate compared to T/AC in TNBC. An anthracycline-free regimen of Cb plus docetaxel (D) also yields high pCR rates in TNBC, and patients achieving pCR with this regimen demonstrate excellent 3-year outcomes without adjuvant anthracycline. This study was designed to compare the efficacy of neoadjuvant regimens CbT→AC and CbD in TNBC. Methods: In this multicenter study, eligible patients with stage I–III TNBC were randomized (1:1) to either paclitaxel 80 mg/m2 every week X 12 + carboplatin (AUC 6) every 3 weeks X 4, followed by doxorubicin 60 mg/m2 + cyclophosphamide 600 mg/m2 every 2 weeks X 4 (CbT→AC, Arm A), or to carboplatin (AUC 6) + docetaxel (75 mg/m2) every 21 days X 6 cycles (CbD, Arm B). The primary endpoint was pCR (no evidence of invasive tumor in the breast and axilla). The two regimens were compared for differences in pCR, residual cancer burden (RCB), treatment delivery, and toxicity. Results: Between 2015 and 2018, 100 patients were randomized; 48 to Arm A and 52 to Arm B. Median age was 52 years, median tumor size was 2.7 cm, 30% were lymph node-positive and 17% carried a BRCA1/2 mutation. Baseline demographic and tumor characteristics were balanced between two arms. pCR was 55% (95%CI: 41%-59%) in Arm A and 52% (95%CI: 39%-65%) in Arm B, p =0.84. RCB 0+1 rate was 67% in both arms. Grade 3/4 adverse events were more common in Arm A compared to Arm B (73% vs 21%, p < 0.0001), with most notable differences in rates of G3/4 neutropenia (Arm A = 60%, Arm B = 8%, p = 0.0001), febrile neutropenia (Arm A = 18%, Arm B = 0%, p = 0.0001), and G3/4 anemia (Arm A = 46%, Arm B = 4%, p = 0.0001). 81% of Arm A patients completed all 4 doses of AC and 4 doses of Cb, and 71% completed > 9 doses of T. 90% of Arm B patients completed all 6 doses of CbD (p = 0.034). Conclusions: The non-anthracycline platinum regimen of CbD yields pCR and RCB 0+1 rates similar to 4-drug regimen of CbTàAC, but with a more favorable toxicity profile and higher treatment completion rate. The CbD regimen should be further explored as a way to de-escalate therapy in TNBC. Clinical trial information: NCT02413320.

Pharmacokinetics of ciclopirox prodrug, a novel agent for the treatment of bladder cancer, in animals and humans

e14705

Background: Ciclopirox Prodrug (CPX-POM) is a novel anticancer agent currently being evaluated in patients with advanced solid tumors participating in a First-in-Human, Phase 1 safety, dose tolerance, pharmacokinetics (PK) and pharmacodynamics trial at four US sites. In vitro and in vivo preclinical proof of principle was established in high grade human urothelial cancer cell lines as well as a mouse model of bladder cancer.Methods: A series of in vivo PK studies were conducted in mice, rats and dogs to characterize the absolute bioavailability of CPX following intravenous (IV), subcutaneous (SC) and oral administration of CPX-POM. The single dose and steady-state plasma and urine pharmacokinetics of CPX-POM are also currently being characterized in patients participating in the ongoing Phase 1 trial. Plasma and urine concentrations of the prodrug and metabolites were determined by LC-MS/MS validated in each specie and matrix. Non-parametric pharmacokinetic parameters were generated from resultant plasma and urine drug and metabolite concentration-time data. Results: CPX-POM is rapidly and completely metabolized to CPX in blood via circulating phosphatases in animals and humans. CPX is completely bioavailable following IV CPX-POM administration in mice, rats and dogs. CPX and its major inactive glucuronide metabolite (CPX-G) are extensively eliminated in urine in all animal species. SC administration of CPX-POM demonstrated excellent bioavailability in rats and dogs. Following IV administration of 30-900 mg/m2CPX-POM to patients, the apparent elimination half-life of CPX ranged from 2 to 8 hours, CPX systemic exposure was dose-proportional and time-independent in cancer patients, and a major portion of the dose was eliminated as CPX-G. Conclusions: IV CPX-POM achieves plasma and urine CPX exposures that exceed in vitro IC50 values several-fold at well tolerated doses in animals and humans. CPX pharmacokinetics observed in animals were predictive of human systemic clearance based on allometric scaling. Clinical trial information: NCT03348514.

BRCA1-No Matter How You Splice It

BRCA1 (breast cancer 1, early onset), a well-known breast cancer susceptibility gene, is a highly alternatively spliced gene. BRCA1 alternative splicing may serve as an alternative regulatory mechanism for the inactivation of the BRCA1 gene in both hereditary and sporadic breast cancers, and other BRCA1-associated cancers. The alternative transcripts of BRCA1 can mimic known functions, possess unique functions compared with the full-length BRCA1 transcript, and in some cases, appear to function in opposition to full-length BRCA1 In this review, we will summarize the functional "naturally occurring" alternative splicing transcripts of BRCA1 and then discuss the latest next-generation sequencing-based detection methods and techniques to detect alternative BRCA1 splicing patterns and their potential use in cancer diagnosis, prognosis, and therapy.

Pleotropic role of RNA binding protein CELF2 in autophagy induction

We previously reported that ionizing radiation (IR) mediates cell death through the induction of CUGBP elav-like family member 2 (CELF2), a tumor suppressor. CELF2 is an RNA binding protein that modulates mRNA stability and translation. Since IR induces autophagy, we hypothesized that CELF2 regulates autophagy-mediated colorectal cancer (CRC) cell death. For clinical relevance, we determined CELF2 levels in The Cancer Genome Atlas (TCGA). Role of CELF2 in radiation response was carried out in CRC cell lines by immunoblotting, immunofluorescence, autophagic vacuole analyses, RNA stability assay, quantitative polymerase chain reaction and electron microscopy. In vivo studies were performed in a xenograft tumor model. TCGA analyses demonstrated that compared to normal tissue, CELF2 is expressed at significantly lower levels in CRC, and is associated with better overall 5-year survival in patients receiving radiation. Mechanistically, CELF2 increased levels of critical components of the autophagy cascade including Beclin-1, ATG5, and ATG12 by modulating mRNA stability. CELF2 also increased autophagic flux in CRC. IR significantly induced autophagy in CRC which correlates with increased levels of CELF2 and autophagy associated proteins. Silencing CELF2 with siRNA, mitigated IR induced autophagy. Moreover, knockdown of CELF2 in vivo conferred tumor resistance to IR. These studies elucidate an unrecognized role for CELF2 in inducing autophagy and potentiating the effects of radiotherapy in CRC.

Mitochondrial polymorphisms contribute to aging phenotypes in MNX mouse models

Many inbred strains of mice develop spontaneous tumors as they age. Recent awareness of the impacts of mitochondrial DNA (mtDNA) on cancer and aging has inspired developing a mitochondrial-nuclear exchange (MNX) mouse model in which nuclear DNA is paired with mitochondrial genomes from other strains of mouse. MNX mice exhibit mtDNA influences on tumorigenicity and metastasis upon mating with transgenic mice. However, we also wanted to investigate spontaneous tumor phenotypes as MNX mice age. Utilizing FVB/NJ, C57BL/6J, C3H/HeN, and BALB/cJ wild-type inbred strains, previously documented phenotypes were observed as expected in MNX mice with the same nuclear background. However, aging nuclear matched MNX mice exhibited decreased occurrence of mammary tumors in C3H/HeN mice containing C57BL/6J mitochondria compared to wild-type C3H/HeN mice. Although aging tumor phenotypes appear to be driven by nuclear genes, evidence suggesting that some differences are modified by the mitochondrial genome is presented.

Metastatic Tumor-in-a-Dish, a Novel Multicellular Organoid to Study Lung Colonization and Predict Therapeutic Response

Metastasis is a major cause of cancer-related deaths. A dearth of preclinical models that recapitulate the metastatic microenvironment has impeded the development of therapeutic agents that are effective against metastatic disease. Because the majority of solid tumors metastasize to the lung, we developed a multicellular lung organoid that mimics the lung microenvironment with air sac-like structures and production of lung surfactant protein. We used these cultures, called primitive lung-in-a-dish (PLiD), to recreate metastatic disease using primary and established cancer cells. The metastatic tumor-in-a-dish (mTiD) cultures resemble the architecture of metastatic tumors in the lung, including angiogenesis. Pretreating PLiD with tumor exosomes enhanced cancer cell colonization. We next tested the response of primary and established cancer cells to current chemotherapeutic agents and an anti-VEGF antibody in mTiD against cancer cells in two-dimensional (2D) or 3D cultures. The response of primary patient-derived colon and ovarian tumor cells to therapy in mTiD cultures matched the response of the patient in the clinic, but not in 2D or single-cell-type 3D cultures. The sensitive mTiD cultures also produced significantly lower circulating markers for cancer similar to that seen in patients who responded to therapy. Thus, we have developed a novel method for lung colonization in vitro, a final stage in tumor metastasis. Moreover, the technique has significant utility in precision/personalized medicine, wherein this phenotypic screen can be coupled with current DNA pharmacogenetics to identify the ideal therapeutic agent, thereby increasing the probability of response to treatment while reducing unnecessary side effects. SIGNIFICANCE: A lung organoid that exhibits characteristics of a normal human lung is developed to study the biology of metastatic disease and therapeutic intervention.

Pathological Response and Survival in Triple-Negative Breast Cancer Following Neoadjuvant Carboplatin plus Docetaxel

PURPOSE

Prognostic value of pathologic complete response (pCR) and extent of pathologic response attained with anthracycline-free platinum plus taxane neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) is unknown. We report recurrence-free survival (RFS) and overall survival (OS) according to degree of pathologic response in patients treated with carboplatin plus docetaxel NAC.

PATIENTS AND METHODS

One-hundred and ninety patients with stage I-III TNBC were treated with neoadjuvant carboplatin (AUC6) plus docetaxel (75 mg/m2) every 21 days × 6 cycles. pCR (no evidence of invasive tumor in breast and axilla) and Residual cancer burden (RCB) were evaluated. Patients were followed for recurrence and survival. Extent of pathologic response was associated with RFS and OS using the Kaplan-Meier method.

RESULTS

Median age was 51 years, and 52% were node-positive. pCR and RCB I rates were 55% and 13%, respectively. Five percent of pCR patients, 0% of RCB I patients, and 58% of RCB II/III patients received adjuvant anthracyclines. Three-year RFS and OS were 79% and 87%, respectively. Three-year RFS was 90% in patients with pCR and 66% in those without pCR [HR = 0.30; 95% confidence interval (CI), 0.14-0.62; P = 0.0001]. Three-year OS was 94% in patients with pCR and 79% in those without pCR (HR = 0.25; 95% CI, 0.10-0.63; P = 0.001). Patients with RCB I demonstrated 3-year RFS (93%) and OS (100%) similar to those with pCR. On multivariable analysis, higher tumor stage, node positivity, and RCB II/III were associated with worse RFS.

CONCLUSIONS

Neoadjuvant carboplatin plus docetaxel yields encouraging efficacy in TNBC. Patients achieving pCR or RCB I with this regimen demonstrate excellent 3-year RFS and OS without adjuvant anthracycline.

Targeted Therapy for EBV-Associated B-cell Neoplasms

Epstein-Barr virus (EBV) is directly implicated in several B-cell lymphoid malignancies. EBV-associated lymphomas are characterized by prominent activation of the NF-κB pathway and targeting this pathway establishes a rationale for a therapeutic approach. The ubiquitin/proteasome signaling plays an essential role in the regulation of the NF-κB pathway. Ixazomib is an FDA-approved, orally bioavailable proteasome inhibitor. Here we report the first preclinical evaluation of ixazomib-mediated growth-inhibitory effects on EBV-infected B-lymphoblastoid cell lines Raji and Daudi. Ixazomib induced apoptosis in these cell lines in a dose-dependent manner. Cell-cycle analysis demonstrated ixazomib treatment induced cell-cycle arrest at the G₂-M phase with a concomitant decrease in G₀-G₁ and S phases. The results further revealed an increase in p53, p21, and p27 levels and a decrease in survivin and c-Myc protein levels. Mechanistically, ixazomib treatment resulted in the accumulation of polyubiquitinated proteins, including phosphorylated IκBα with a significant reduction of p65 subunit nuclear translocation. Altogether, our preclinical data support the rationale for in vivo testing of ixazomib in EBV-associated B-cell neoplasms. IMPLICATIONS: This preclinical study supports the use of oral proteasome inhibitor ixazomib for targeting NF-κB signaling in the treatment of EBV-associated B-cell neoplasms.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/17/4/839/F1.large.jpg.

Abstract 5882: Bench-to-bedside translation of ciclopirox prodrug for the treatment of non-muscle invasive and muscle-invasive bladder cancer

Ciclopirox (CPX) is contained in a number of FDA-approved topical antifungal drug products as the free acid and olamine salt. CPX possesses anticancer activity in a number of in vitro and in vivo preclinical models. Its clinical utility is limited as an oral anticancer agent, however. The oral bioavailability of CPX is quite low due to extensive first pass effect. The poor water solubility of CPX and its olamine salt prevent formulation as an injectable drug product. Thirdly, dose-limiting gastrointestinal toxicities were observed following four times daily oral dosing of CPX in patients with advanced hematologic malignancies. Ciclopirox Prodrug (CPX-POM), in contrast, has demonstrated excellent bioavailability via injectable routes of administration. Here we describe the preclinical characterization of CPX-POM, a novel anticancer agent being developed for the treatment of non-muscle invasive (NMIBC) and muscle invasive (MIBC) bladder cancer. Following IV, SQ and IP administration to mice, CPX-POM is rapidly and completely metabolized to CPX in blood via circulating phosphatases. CPX and its major, inactive glucuronide metabolite are extensively eliminated in urine. At well-tolerated doses, steady-state urine concentrations of CPX exceed in vitro IC50 values in mice by 15-30 fold. CPX inhibited cell proliferation, colony formation, and bladdosphere formation in vitro in T24 (NMIBC) and 253JBV (MIBC) human cell lines in both concentration- and time-dependent manners with IC50 values of 2-4 µM. CPX exposure increased the percentage of NMIBC and MIBC cells arrested at the S and G0/G1 phases, and induced cell death. CPX exposure significantly reduced expression of genes at the mRNA level involved in cancer stem cell signaling pathways including Notch, Wnt, and Hedgehog. CPX was shown to inhibit bladder cancer cell growth in vitro by inhibiting the Notch 1 signaling pathway. The validated N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) chemical carcinogen mouse model of bladder cancer was employed to establish in vivo preclinical proof of principle for CPX-POM. Over the once-daily IP dose range of 25-200 mg/kg, CPX-POM treatment resulted in significant decreases in bladder weight, a clear migration to lower stage tumors, dose-dependent reduction in Ki67 and PCNA staining, as well as a reduction in PCNA-expressing cells. All CPX-POM doses were well tolerated with no evidence of toxicity to the urinary tract based on blinded pathologic evaluation. There were also dose-dependent decreases in Notch 1, Presenilin 1, and Hey 1 in bladder cancer tissues obtained from CPX-POM treated animals. Tumor response was similar, in vivo, following once-daily and three-times weekly CPX-POM administration. CPX-POM has received FDA clearance to proceed to Phase I, and is currently being evaluated in a first-in-human trial in patients with advanced solid tumors.

Citation Format: Scott J. Weir, Partha Ranjarajan, Robyn Wood, Karl Schorno, Prabhu Ramamoorthy, Lian Rajweski, Kathy Heppert, Michael J. McKenna, William McCulloch, Greg A. Reed, Amanda Brinker, Michael J. Baltezor, Roy A. Jensen, John A. Taylor, Shrikant Anant. Bench-to-bedside translation of ciclopirox prodrug for the treatment of non-muscle invasive and muscle-invasive bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5882.

Abstract 5032: Tumor in a Dish (TiD): Novel approach for precision therapy using patient-derived cells

Metastatic colorectal cancer is a major cause of cancer-related deaths. Most patients with metastatic disease fail to respond to current chemotherapeutic agents. Current, traditional culture model is not appropriate to study the metastatic disease in in vitro condition. Hence, there is an ominous need for developing new therapeutic and preventive agents that can target metastatic cancer. Unfortunately, there are no good in vitro as well as in vivo models available for studying metastatic disease. Hence, in this abstract, we demonstrate the development of a new lung model system, called Primitive Lung in a Dish or PLiD with cancer cells called “Tumor in a Dish” or TiD. The PLiD system shows expression of specific cell type marker like E-cadherin (epithelial cell) vimentin (fibroblast), CD31 (heme-endothelial cells) and LYVE1 (lymph-endothelial cells). Interestingly, we showed expression of lung functional protein like surfactant protein B and D. In the multicell type TiD system, cancer cells were grown in a 3-dimensional (3D) PLiD system containing normal epithelial cells, fibroblasts and endothelial cells. The model resembles in vivo tumor microenvironments, including cell-cell contact, tumor architecture, and the influence of different cell types. We next determined the efficacy of standard colon cancer chemotherapeutic agents. We observed differential activity of 5FU in TiD system when compared to standard 2D and single-cell type 3D cultures. Another surprising result we found was with freshly isolated colon cancer cells from patient samples. Without knowing the genetic characteristics of the cancer tissue, the TiD system was able to identify cells that were resistant to oxaliplatin. Moreover, using this method, we have developed novel drugs that target cancer cells while not affecting the normal tissue. More importantly, the technique has significant utility in precision/personalized medicine, wherein this phenotypic screen can be coupled with current DNA pharmacogenetics to identify the ideal therapeutic agent, thereby increasing the probability of response to treatment while reducing unnecessary side effects.

Citation Format: Prabhu Ramamoorthy, Sufi Thomas, Sathish Ramalingam, Gaurav Fnu, Sita G. Sittampalam, Roy A. Jensen, Shrikant Anant. Tumor in a Dish (TiD): Novel approach for precision therapy using patient-derived cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5032.

Lysine methyltransferase SMYD2 promotes triple negative breast cancer progression

We identified SMYD2, a SMYD (SET and MYND domain) family protein with lysine methyltransferase activity, as a novel breast cancer oncogene. SMYD2 was expressed at significantly higher levels in breast cancer cell lines and in breast tumor tissues. Silencing of SMYD2 by RNAi in triple-negative breast cancer (TNBC) cell lines or inhibition of SMYD2 with its specific inhibitor, AZ505, significantly reduced tumor growth in vivo. SMYD2 executes this activity via methylation and activation of its novel non-histone substrates, including STAT3 and the p65 subunit of NF-κB, leading to increased TNBC cell proliferation and survival. There are cross-talk and synergistic effects among SMYD2, STAT3, and NF-κB in TNBC cells, in that STAT3 can contribute to the modification of NF-κB p65 subunit post-translationally by recruitment of SMYD2, whereas the p65 subunit of NF-κB can also contribute to the modification of STAT3 post-translationally by recruitment of SMYD2, leading to methylation and activation of STAT3 and p65 in these cells. The expression of SMYD2 can be upregulated by IL-6-STAT3 and TNFα-NF-κB signaling, which integrates epigenetic regulation to inflammation in TNBC development. In addition, we have identified a novel SMYD2 transcriptional target gene, PTPN13, which links SMYD2 to other known breast cancer associated signaling pathways, including ERK, mTOR, and Akt signaling via PTPN13 mediated phosphorylation.

Abstract P4-10-06: Influence of older age on triple negative breast cancer (TNBC) clinical-pathological characteristics and outcomes

Background: The impact of age at diagnosis on clinical presentation and treatment delivery for triple negative breast cancer (TNBC) is unclear. Utilizing data from a prospective registry, the aim of this study was to further elucidate the age-dependent correlation between TNBC clinical-pathological features, and the implications of age-bias on treatment delivery and prognosis.

Methods: 480 subjects with stage I-III TNBC were enrolled in an IRB approved multisite prospective registry between 2011 and 2016. Clinical, demographic, treatment information was collected and patients were followed for recurrence and survival. Patients were categorized as older (&gt;60 years) or younger groups (&lt;60 years). Recurrence free survival (RFS) and overall survival (OS) were estimated according to the Kaplan-Meier method and compared among groups by log-rank test.

Results: 145 (30%) of 480 TNBC patients were older (&gt; 60 years) at time of diagnosis. Compared to younger patients, older patients were more likely to present with screen detected vs symptomatic cancer (47% vs 25% p=&lt;0.001), more likely to have node negative cancer (71% vs 61% p=0.030), stage I disease (42% vs 28% p=0.003), and low level (1-10%) ER or PR positivity (19% vs 12% p=0.046). Compared to the younger patients, older patients were less likely to have a BRCA1/2 mutation (6% vs 23% p=0.0002) but more likely to have a prior history of hormone positive breast cancer (7% vs 1% p=0.0002). Compared to younger counterparts, older patients were less likely to receive neo/adjuvant chemotherapy (93% vs 99% p=0.0006), and less likely to receive &gt; 4 cycles of neo/adjuvant chemotherapy (61% vs 78%, p=0.0003). Three year RFS for the entire cohort was 80% and was identical for older and younger patients at 80%. Three year OS for the entire cohort was 87% and was similar for older and younger patients. On multivariable analysis only tumor size and nodal status significantly impacted RFS.

Conclusions: A significant fraction (30%) of TNBC patients are older (&gt; 60 years) at time of diagnosis. Despite presenting a with more favorable disease stage, older TNBC patients did not demonstrate better outcomes compared to the higher risk younger patients. The underlying reasons for this observation may be tumor biology differences between older and younger TNBC patients or perhaps could be related to underutilization of appropriate systemic chemotherapy (39% of older patients received &lt; 4 cycles of chemotherapy). Further studies are warranted on this subject.

Citation Format: Mina A, Lehn C, Wang YY, Klemp JR, O'Dea AP, Elia M, Hoffmann M, Crane G, Sheehan M, Madhusudhana S, Jensen RA, Godwin AK, Khan QJ, Kimler BF, Sharma P. Influence of older age on triple negative breast cancer (TNBC) clinical-pathological characteristics and outcomes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-10-06.

Mitochondrial Haplotype Alters Mammary Cancer Tumorigenicity and Metastasis in an Oncogenic Driver-Dependent Manner

Using a novel mouse model, a mitochondrial-nuclear exchange model termed MNX, we tested the hypothesis that inherited mitochondrial haplotypes alter primary tumor latency and metastatic efficiency. Male FVB/N-Tg(MMTVneu)202Mul/J (Her2) transgenic mice were bred to female MNX mice having FVB/NJ nuclear DNA with either FVB/NJ, C57BL/6J, or BALB/cJ mtDNA. Pups receiving the C57BL/6J or BALB/cJ mitochondrial genome (i.e., females crossed with Her2 males) showed significantly (P < 0.001) longer tumor latency (262 vs. 293 vs. 225 days), fewer pulmonary metastases (5 vs. 7 vs. 15), and differences in size of lung metastases (1.2 vs. 1.4 vs. 1.0 mm diameter) compared with FVB/NJ mtDNA. Although polyoma virus middle T-driven tumors showed altered primary and metastatic profiles in previous studies, depending upon nuclear and mtDNA haplotype, the magnitude and direction of changes were not the same in the HER2-driven mammary carcinomas. Collectively, these results establish mitochondrial polymorphisms as quantitative trait loci in mammary carcinogenesis, and they implicate distinct interactions between tumor drivers and mitochondria as critical modifiers of tumorigenicity and metastasis. Cancer Res; 77(24); 6941-9. ©2017 AACR.

Abstract 3227: Novel Marmelin analog DBQ targets Notch signaling pathway in colon cancer stem cells

Background: Colon cancer is the second leading cause of death in the United States. Previously, we have reported that the identification of a novel compound Marmelin from Aegle marmelos and potent anti-colon cancer activity. We have developed novel Marmelin analogue THB from this structure showed potent anti-cancer activity and its inhibitory constant value was 10 µM. From this, we developed a second series of analogs, of which DBQ is even more potent than THB. The current study is designed to determine whether DBQ affects colon cancer stem cells and identify a mechanism.

Method: Colon cancer cell lines HCT116 and SW480 and normal colon epithelial cells were used in the study. Cell growth was measured by hexoseaminidase and clonogenicity assays. Apoptosis was determined by measuring caspase 3/7 activities. Colosphere formation assay and FACS sorting were used for stem cells. For in vivo effects, we performed studies in HCT116 tumor xenografts. Immunohistochemistry was determined for stem cell markers and Notch signaling proteins.

Results: DBQ treatment induced significant dose-dependent inhibition of proliferation and colony formation of HCT116 and SW480 cells, but not that of the normal FHC colon epithelial cells. DBQ also significantly reduced the number and size of colospheres, suggesting effects on stem cells. In addition, DBQ reduced the levels of colon stem cell marker proteins DCLK1, LGR5, and CD44. We obtained further confirmation by flow cytometry, where DBQ treatment reduced the number of DCLK1+ cells. We next determined whether DBQ affects the Notch signaling, a pathway that is important in maintaining CSC population. Notch receptor and its ligands are up-regulated in human colon cancer tissues. DBQ treatment significantly downregulated the expression of all four Notch isoforms, its ligands Jagged 1, 2 and DLL1, 3, 4 and downstream target protein Hes1. Notch activation requires cleavage by the γ-secretase complex. DBQ treatment inhibits the expression of γ-secretase complex proteins. To confirm that DBQ effect is thorough downregulating Notch activation, we ectopically expressed the Notch Intracellular domain. DBQ effect was significantly mitigated in this condition. To determine the effect of DBQ on tumor growth in vivo, we administered DBQ intraperitoneally (5mg/kg bw) every day for 21 days in mice carrying HCT116 tumor xenografts. DBQ treatment significantly suppressed tumor xenograft growth, with notably lower tumor volume and weight. Western blot and immunohistochemistry analyses demonstrated significant inhibition of CSC marker proteins DCLK1, LGR5 and CD44 and also the Notch signaling proteins in the DBQ-treated xenograft tissues.

Conclusion: Together, these data suggest that DBQ treatment suppresses colon cancer growth that targets stem cells in part by inhibiting Notch signaling pathway.

Citation Format: Dharmalingam Subramaniam, Sivapriya Ponnurangam, Prasad R. Dandawate, Gaurav Kaushik, Ossama W. Tawfik, Roy A. Jensen, Santimukul Santra, Subhash B. Padhye, Scott J. Weir, Shrikant Anant. Novel Marmelin analog DBQ targets Notch signaling pathway in colon cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3227. doi:10.1158/1538-7445.AM2017-3227

Abstract P5-16-02: Pathological complete response is associated with excellent outcomes in BRCA mutation associated triple negative breast cancer

Introduction: Pathological complete response (pCR) in unselected triple negative breast cancer (TNBC) is associated with excellent long-term survival. However, controversy remains as to whether pCR in BRCA mutation associated (BRCA[+]) TNBC is predictive of improved long-term outcome. A recent study suggests that pCR was not a surrogate for outcomes in BRCA1 associated TNBC. All of the patients in this study harbored an Ashkenazi Jewish founder BRCA1 mutation and the majority of mutation carriers underwent lumpectomy. Impact of pCR as it relates to BRCA status in a larger, heterogeneous TNBC cohort treated in a contemporary time frame is not known.

Aim: Evaluate and compare the prognostic impact of pCR as it relates to the BRCA mutation status in patients enrolled in a prospective multisite TNBC registry.

Methods: 453 patients with stage I-III TNBC were enrolled within a multisite registry between 2011- 2015, out of which 173 received neoadjuvant chemotherapy (NAC) and also underwent germline BRCA testing. pCR in the breast and axilla was evaluated and patients were followed for reoccurrence and survival. Recurrence free survival (RFS) was estimated according to the Kaplan-Meier method and compared among groups with log-rank statistic.

Results: For the 173 eligible patients the median age was 49 years; African-American:14%; median tumor size:3 cm; 42%:Lymph node positive; and 18% (32/173) demonstrated BRCA mutation (BRCA1=28, BRCA2=4). All patients received anthracycline and/or taxane based NAC. pCR rates for BRCA[+] and wild type (BRCA[-]) patients was 72% and 46% respectively (p=0.01). 97% of BRCA[+] and 42% of BRCA[-] patients underwent bilateral mastectomy (p=0.001). The three year RFS was 92% and 81% in BRCA[+] and BRCA[-] patients, respectively (p=0.18). Attainment of pCR was associated with excellent 3 year RFS of 95% and 97% in BRCA[+] and BRCA[-] patients, respectively (p=0.85). Among BRCA[-] patients lack of pCR was associated with significantly worse 3 year RFS (70% RFS in patients without pCR, compared to 97% in patients with pCR; p=0.001). Among BRCA[+] patients lack of pCR was associated with numerically lower but not statistically significant worse 3 year RFS (83% RFS in patients without pCR, compared to 95% in patients with pCR; p=0.41). On multivariable Cox regression analysis, only stage III disease was associated with higher risk of relapse (p&lt;0.001).

Conclusions: Our observation of higher pCR in BRCA-carriers compared to wild-type TNBC patients is consistent with previously published literature. In this contemporary cohort of TNBC patients for whom the majority of BRCA[+] patients underwent bilateral mastectomy, attainment of pCR carried an excellent prognosis in both BRCA[+] and BRCA[-] patients. On the other hand, BRCA[+] patients who do not attain pCR may have better outcomes compared to BRCA[-] patients without pCR. Further research to explore the underlying biological mechanisms involved in tumor response and relapse in BRCA[+] and BRCA[-] TNBC patients is needed. Furthermore, given these observations, germline BRCA mutation status should be used as a stratification variable in studies evaluating pCR and long term outcomes with investigational therapies in TNBC.

Citation Format: Prochaska LH, Godwin AK, Kimler BF, Lehn C, Klemp JR, O'Dea A, Elia M, Hoffmann MS, Crane G, McKittrick R, Sheehan M, Graff SL, Madhusudhana S, Khan QJ, Jensen RA, Sharma P. Pathological complete response is associated with excellent outcomes in BRCA mutation associated triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-02.

Quinomycin A targets Notch signaling pathway in pancreatic cancer stem cells

Cancer stem cells (CSCs) appear to explain many aspects of the neoplastic evolution of tumors and likely account for enhanced therapeutic resistance following treatment. Dysregulated Notch signaling, which affects CSCs plays an important role in pancreatic cancer progression. We have determined the ability of Quinomycin to inhibit CSCs and the Notch signaling pathway. Quinomycin treatment resulted in significant inhibition of proliferation and colony formation in pancreatic cancer cell lines, but not in normal pancreatic epithelial cells. Moreover, Quinomycin affected pancreatosphere formation. The compound also decreased the expression of CSC marker proteins DCLK1, CD44, CD24 and EPCAM. In addition, flow cytometry studies demonstrated that Quinomycin reduced the number of DCLK1+ cells. Furthermore, levels of Notch 1–4 receptors, their ligands Jagged1, Jagged2, DLL1, DLL3, DLL4 and the downstream target protein Hes-1 were reduced. The γ-secretase complex proteins, Presenilin 1, Nicastrin, Pen2, and APH-1, required for Notch activation also exhibited decreased expression. Ectopic expression of the Notch Intracellular Domain (NICD) partially rescued the cells from Quinomycin mediated growth suppression. To determine the effect of Quinomycin on tumor growth in vivo, nude mice carrying tumor xenografts were administered Quinomycin intraperitoneally every day for 21 days. Treatment with the compound significantly inhibited tumor xenograft growth, coupled with significant reduction in the expression of CSC markers and Notch signaling proteins. Together, these data suggest that Quinomycin is a potent inhibitor of pancreatic cancer that targets the stem cells by inhibiting Notch signaling proteins.

Targeting cancer stem cells and signaling pathways by phytochemicals: Novel approach for breast cancer therapy

Breast cancer is the most common form of cancer diagnosed in women worldwide and the second leading cause of cancer-related deaths in the USA. Despite the development of newer diagnostic methods, selective as well as targeted chemotherapies and their combinations, surgery, hormonal therapy, radiotherapy, breast cancer recurrence, metastasis and drug resistance are still the major problems for breast cancer. Emerging evidence suggest the existence of cancer stem cells (CSCs), a population of cells with the capacity to self-renew, differentiate and be capable of initiating and sustaining tumor growth. In addition, CSCs are believed to be responsible for cancer recurrence, anticancer drug resistance, and metastasis. Hence, compounds targeting breast CSCs may be better therapeutic agents for treating breast cancer and control recurrence and metastasis. Naturally occurring compounds, mainly phytochemicals have gained immense attention in recent times because of their wide safety profile, ability to target heterogeneous populations of cancer cells as well as CSCs, and their key signaling pathways. Therefore, in the present review article, we summarize our current understanding of breast CSCs and their signaling pathways, and the phytochemicals that affect these cells including curcumin, resveratrol, tea polyphenols (epigallocatechin-3-gallate, epigallocatechin), sulforaphane, genistein, indole-3-carbinol, 3, 3'-di-indolylmethane, vitamin E, retinoic acid, quercetin, parthenolide, triptolide, 6-shogaol, pterostilbene, isoliquiritigenin, celastrol, and koenimbin. These phytochemicals may serve as novel therapeutic agents for breast cancer treatment and future leads for drug development.

Abstract 1310: Targetingprolactin signaling to suppress pancreatic cancer stem cells

Background: Pancreatic cancer (PCa) is a major cause of cancer related mortality in United States with &lt; 6% survival rate. It is an aggressive and devastating disease, which is characterized by poor prognosis, invasiveness, rapid progression, profound resistance to drug treatment and recurrance after surgery. Presently, single agent based chemotherapy (e.g. Gemcitabine) is the major treatment for metastatic adenocarcinoma of pancreas but it has a tumor response rate of below 10%. Moreover combination therapy of gemcitabine and erlotinib only marginally improved survival rate. Hence, there is a dire need to identify novel ways to inhibit pancreatic cancer growth.

Methods: PCa cells (MiaPaCa-2 and PanC-1) were grown to 70-80% of confluency and treated with and without prolactin (PRL) and JAK2, STAT3 and ERK phosphorylation in presence and absence of antipsychotic compound were evaluated by western blot. Growth of PCa lines (MiaPaCa-2, PanC-1, BxPC-3, AsPC-1) and normal ductal epithelial cells (HPNE) was measured by hexosaminidase and clonogenicity, respectively. Pancosphere formation was used to identify effects on stem cells.

Results: We have recently identified that the receptor for the pituitary hormone prolactin is overexpressed in pancreatic cancers, and in pancreatic cancer cell lines. When prolactin (PRL) binds its cognate receptor (PRLR), it induces various downstream events including the JAK-STAT and ERK MAPK pathways. In pancreatic cancer cell lines, we observe that PRL treatment induced dose- and time-dependent JAK2, STAT3, and ERK1/2 phosphorylation. Furthermore, there was an increase in the expression of cancer stem cell (CSC) markers DCLK1 (doublecortin calmodulin like kinase 1) and CD44. In addition, PRL-induced pancosphere formation further suggesting that PRL affects stem cells. Based on these data, we conclude that PRL signaling enhances stemness in pancreatic cancers, and therefore we decided to target it for therapeutic intervention. For this, we developed a homology model for the C-terminal intracellular region of the receptor and performed a virtual screening in silico with FDA approved drugs. One compound, a first generation antipsychotic drug diphenylbutylpiperidine, also called Penfluridol was found to interact with the region of the receptor that also binds site for JAK2. The compound has a long half-life, and is used in the treatment of chronic schizophrenia and similar psychotic disorders. We have further determined that Penfluridol inhibits PRL-induced STAT3 and ERK phosphorylation. In addition, the compound reduced proliferation, colony formation, and spheroid formation. Moreover, it induced cells to undergo autophagy by activating LC3B and increasing expression of autophagy-related genes ATG5, 7 and 12.

Conclusions: PRL signaling through its cognate PRLR receptor is critical for aggressive pancreatic cancer behavior, and therefore may be an effective therapeutic strategy.

Citation Format: Prasad Dandawate, Gaurav Kaushik, Dharmalingam Subramaniam, Prabhu Ramamoorthy, Scott J. Weir, Roy A. Jensen, Shrikant Anant. Targetingprolactin signaling to suppress pancreatic cancer stem cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1310.

Abstract 4748: Targeting colon cancer stem cells: Novel marmelin analog THB suppresses DCLK1 and Notch Signaling

Background: Despite therapeutic advances, colon cancer remains the second leading cause of death in the United States. Previously, we have reported that the identification of a novel compound, HDNC or Marmelin from Aegle marmelos with potent anti-colon cancer activity. We have now developed a novel marmelin analogue THB and made it water soluble THB using β-cyclodextrin (THBCD). The current study is designed to determine whether THB affects stem cells and to identify a mechanism.

Method: Colon cancer cell lines HCT116 and SW480 and normal colon epithelial cells were used in the study. Cell growth was measured by hexoseaminidase and clonogenicity assays. Apoptosis was determined by measuring caspase 3/7 activities. Colosphere formation assay and FACS sorting were used for stem cells. For in vivo effects, we have performed HCT116 cells induced tumor xenografts. Immunohistochemistry was determined for stem cell markers and Notch signaling proteins.

Results: THB treatment induced a significant dose-dependent inhibition of proliferation and colony formation of the two colon cancer cell lines, but not that of the normal cells. To demonstrate THB effects on stem cells, we performed colosphere assays. THB treatment significantly reduced the number and size of colospheres, suggesting effects on stem cells. In addition, colon stem cell marker proteins DCLK1, LGR5, and CD44 were also decreased. Further proof was obtained by flow cytometry analyses, where THB reduced the number of DCLK1+ cells. We next determined whether THB affects the Notch signaling pathway, a pathway that is important in maintaining CSC population. Notch receptor and its ligands are up-regulated in human colon cancer tissues. THB treatment significantly downregulated the expression of Notch1, its ligand Jagged1 and downstream target protein Hes1. Notch activation requires cleavage by the γ-secretase complex. THB treatment inhibits the expression of γ-secretase complex proteins Presenilin1, Nicastrin, APH1 and PEN2. Moreover, ectopic expression of the Notch Intracellular domain (NICD) rescued the cells from THB mediated growth suppression. These data demonstrate that THB mediated effects of colon cancer stem cells is in part through downregulating Notch1 activation. To determine the effect of THB on tumor growth in vivo, mice carrying HCT116 tumor xenografts were administered the compound intraperitoneally (5mg/kg bw) every day for 21 days. THB treatment significantly suppressed tumor xenograft growth, with notably lower tumor volume and weight. Western blot and immunohistochemistry analyses demonstrated significant inhibition of CSC marker proteins DCLK1, LGR5 and CD44 and also the Notch signaling proteins in the THB-treated xenograft tissues.

Conclusion: Together, these data suggest that THB treatment suppresses colon cancer growth that targets stem cells by inhibiting Notch1 signaling pathway.

Citation Format: Dharmalingam Subramaniam, Sivapriya Ponnurangam, Prasad R. Dandawate, Ossama W. Tawfik, Roy A. Jensen, Scott J. Weir, Subhash B. Padhye, Shrikant Anant. Targeting colon cancer stem cells: Novel marmelin analog THB suppresses DCLK1 and Notch Signaling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4748.

Abstract 4632: Effects of Hsp90 inhibitors on triple-negative breast cancer: BRCA1 as a therapeutic target for TNBC

Background: Breast cancer is the second leading cause of death for woman. Within breast cancer, those classified as Triple Negative Breast Cancer (TNBC) exhibit dismal survival rates due to their propensity to develop distant metastases. Heat shock protein 90 (Hsp90) is a molecular chaperone that aids in the folding and maturation of various proteins involved in breast cancer progression and resistance to therapy. The aim of this study was to elucidate whether the two natural inhibitors of Hsp90, celastrol and triptolide inhibit triple negative breast cancer growth. Both these compounds are terpenoids and were obtained from the Chinese herb “Thunder God of Vine” (Tripterygium wilfordii).

Methods: BT20, BT549, MDA-MB-157 and MDA-MB-231 cells (all TNBC cells), and immortalized human mammary epithelial cells (HMLE) were grown in DMEM containing 10% FBS as per ATCC recommendations. Cell proliferation was assessed by hexoseaminidase activity, and IC50 values calculated using GraphPad Prism5. For clonogenicity, 500 cells were incubated with IC50 concentrations of each compound for 24 h, after which they were allowed to grow and form colonies. For in vivo, BT20 cells were injected into flanks of athymic nude mice and treated with celastrol and triptolide at 3 mg/Kg bw and 0.25 mg/Kg bw, respectively.

Results: Celastrol and triptolide treatment suppressed proliferation and colony forming ability of all four TNBC cell lines, but not that of the immortalized HMLE cells. The compounds increased apoptotic cell death, based on increased Annexin V staining. Moreover, there was increased expression of the pro-apoptotic protein Bax but decreased expression of the anti-apoptotic protein, Bcl2 and BclXL. Immunoprecipitation-coupled western blots also showed that the compounds inhibit HSP90/CDC37 complex formation. Interestingly, the coupled immunoprecipitation-western blot analyses showed increased HSP90-BRCA1 interaction after treatment with the compounds. Coupled to this, western blot and immunostaining assays showed increased cytosolic levels and reduced nuclear levels of BRCA1 protein. Similar results were obtained in vivo with BT20 xenografts. In addition to decreased tumor size in response to treatment with celastrol or triptolide, the xenograft tissues showed an increase in cytoplasmic BRCA1 levels following treatment. In addition, there was increased in HSP90-BRCA1 complex formation in the treated xenograft tissues. Finally, knockdown of BRCA1 using specific silencer RNA resulted in partial inhibition in cell growth reduction after celastrol and triptolide treatment in both BT20 and MDA-MB-231 cells.

Conclusion: Taken together, these data suggest that both celastrol and triptolide suppress TNBC cell growth, in part through increasing cytosolic HSP90/BRCA1 complex formation.

Citation Format: Prabhu Ramamoorthy, Parthasarathy Rangarajan, Ossama Tawfik, Shrikant Anant, Roy A. Jensen. Effects of Hsp90 inhibitors on triple-negative breast cancer: BRCA1 as a therapeutic target for TNBC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4632.