Abstract P6-20-10: Role of GPR110 in breast cancer

Our long-term goal is to discover adhesion GPCR targets in breast cancer. Our previous studies have found GPR110 to be overexpressed in tumorigenic cell population as well as in anti-HER2 drug-resistant derivatives of HER2+ breast cancer cells. In subsequent studies, we found that GPR110 knockdown inhibited anchorage-independent cell growth, mammosphere formation, and invasion/migration of HER2+ breast cancer cells. Conversely, overexpression of GPR110 by lentiviral delivery of cDNA enhanced anchorage-independent cell growth, mammosphere formation, and invasion/migration in HER2+ breast cancer cells. In addition, GPR110 overexpression led to increase in the % of Aldefluor-positive tumorigenic cell population, further emphasizing the role of GPR110 as a mediator of tumorigenesis in addition to the metastatic processes in HER2+ breast cancer. Among various subtypes of breast cancer, GPR110 expression was higher in HER2+ and basal subtypes, most of which are triple-negative (negative for ER, PR, and HER2), compared to luminal A and B subtypes. GPR110 was either gene amplified or upregulated in 4% of all breast cancers based on the publicly available TCGA dataset. GPR110 overexpression predicted poorer recurrence-free survival in triple-negative breast cancer. Furthermore, GPR110 was overexpressed in brain metastatic lesions compared to mammary tumors in patient-derived xenograft models of triple-negative breast cancer (WHIM2 and WHIM30). Knocking down GPR110 reduced anchorage-dependent and -independent cell growth, mammosphere formation, and invasion/migration of triple-negative breast cancer cells. Overall, our results suggest that GPR110 may be a potential drug target in HER2+ and triple-negative breast cancer. Drug discovery efforts to identify GPR110 antagonists will provide useful pharmacological tools for validating GPR110 as a drug target in breast cancer. Since GPR110 is also overexpressed in various other types of cancer, understanding the mechanism of GPR110 upregulation and signaling in cancer is an important future direction.

This work was supported by the Department of Defense Grants W81XWH-14-1-0340 and W81XWH-14-1-0341 to Drs. Trivedi and Schiff, respectively.

Citation Format: Bhat R, Qin L, De Angelis C, Sahay D, Bhargava D, Creighton C, Yadav P, Yazdanfard S, Alrawi A, Yadav V, Vasaikar S, Nanda S, Sethunath V, Fu X, Zhang B, Narkar V, Schiff R, Trivedi M. Role of GPR110 in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-20-10.

Abstract P6-17-12: Neratinib in combination with trastuzumab is superior to each alone and to pertuzumab plus trastuzumab in HER2-positive in vivo breast cancer models

Background: Lapatinib (L) plus trastuzumab (T) alone or with endocrine therapy for HER2+/ER+ tumors but without chemotherapy, yielded complete tumor eradication in xenograft models. In neoadjuvant trials (NCT00548184, 00999804, 01973660), a substantial number of patients achieved pathologic complete response with this same strategy. The irreversible pan-HER inhibitor neratinib (N) has been recently approved by the FDA for early stage HER2+ breast cancer and has shown greater potency compared to L in the preclinical setting. However, the therapeutic efficacy of N in combination with T (N+T) and how it compares to pertuzumab (P) +T (without chemotherapy) has not been well studied.

We hypothesize that dual HER2 inhibition using N+T will be highly efficacious and more effective than P+T due to more complete blockade of the HER pathway. Here, we evaluate the therapeutic efficacy of N, P, and T, either alone or in combination, with a primary focus on comparing N+T vs. P+T in established cell line- and patient-derived xenograft (PDX) models.

Methods: Athymic nude and SCID/Beige mice bearing BT474-AZ cell line (ER+/HER2+), and BCM-3963 PDX tumors (ER-/HER2+, wild-type PIK3CA), respectively were randomized to vehicle, N (20mg/kg, 5 days/week), T (10mg/kg, twice a week), P (6mg/kg, once a week), N+T, or P+T, with simultaneous estrogen (E2) deprivation (ED) in BT474-AZ model. Treatment response was assessed by biweekly tumor measurements. Study endpoints included time to tumor regression (TTR) and progression (TTP) (tumor halving/doubling over baseline, respectively), and the rate and time of complete response (CR and TCR, respectively). Results were analyzed using survival analysis (Kaplan-Meier estimates) and generalized Wilcoxon tests.

Results: In the BT474-AZ model, mice treated with E2+vehicle and ED+vehicle showed steady tumor growth, with a median TTP of 8 and 25 days, respectively. While tumor regression was observed in 100% of mice treated with N, P, T, N+T, and P+T, tumors treated with N+T regressed faster compared to P (p<0.001), T (p=0.004), and P+T (p=0.044). Further, N+T was superior to N (p=0.018) and T (p=0.007) alone in achieving accelerated CR. In the BCM-3963 model, tumors treated with vehicle, T, P, and P+T continued to grow with a median TTP of 11, 16, 19, and 17 days, respectively. In contrast, CR was achieved in 100% of N and N+T treated mice. Importantly, combining N with T accelerated the attainment of CR compared to N alone (p=0.026). Molecular and pathologic analysis of short-term treated tumors in both models to evaluate alterations in HER signaling, cell proliferation, and apoptosis is ongoing.

Model/TreatmentN of miceMedian TTP (Days)Median TTR (Days)Median TCR (Days)CR (%)BT474-AZ     E2+Vehicle98--0ED+Vehicle1025--0ED+N13-214100ED+T12-519100ED+P12-185492ED+N+T13-210100ED+P+T14-414100BCM-3963     Vehicle1511--0N15-417100T1416--0P1319--0N+T19-614100P+T1617--0

Conclusions: Our findings establish the preclinical efficacy of combining N with T for HER2+ breast cancer and warrant further clinical testing to investigate the efficacy of N+T without chemotherapy in the neoadjuvant setting for patients with HER2+ breast cancer.

Citation Format: Veeraraghavan J, Sethunath V, Qin L, Shea MJ, Mitchell T, De Angelis C, Nanda S, Diala I, Lalani AS, Hilsenbeck SG, Rimawi MF, Osborne CK, Schiff R. Neratinib in combination with trastuzumab is superior to each alone and to pertuzumab plus trastuzumab in HER2-positive in vivo breast cancer models [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-12.

Abstract P4-04-03: Hyperactive FOXA1 activates super-enhancer-engaged HIF2α/EPAS1 to promote endocrine-resistant metastatic ER-positive breast cancer

Background: We have recently reported that acquired endocrine resistance (Endo-R) in multiple ER+ breast cancer (BC) Endo-R cell models is driven by high levels of FOXA1 (High-FOXA1), via gene amplification and/or overexpression (OE), leading to coordinated reprogramming of the FOXA1 genomic binding (cistrome) and transcriptome. Forced FOXA1 OE in parental (P) cells induced similar transcriptional reprogramming leading to Endo-R and metastasis. Recent clinical data showing enrichment of FOXA1 amplification in ER+ metastases further support the clinical importance of our findings. However, the molecular components and the mechanism of High-FOXA1-induced transcriptional reprogramming in Endo-R and metastasis are unknown.

Methods: High-FOXA1-containing MCF7 tamoxifen-resistant (TamR) and P/FOXA1-OE cells were used in this study. An integrative multi-OMICS approach was employed to analyze transcriptome (RNA-seq), FOXA1 cistrome, and histone H3K27 acetylation (ac) (ChIP-seq). Intersection of High-FOXA1-induced transcriptome and distinct FOXA1 cistrome-predicted genes defined a High-FOXA1 core gene signature (CGS). Gene Set Enrichment Analysis (GSEA) and Gene Ontology (GO) were used for functional annotation. Cell growth and migration/invasion were measured by a bright-field automated cell counter and Transwell insert system. Altered gene expression was measured by RT-qPCR. High-FOXA1 signaling inhibition included gene knockdown (siRNA) or pharmacologic blockade (the EPAS1 inhibitor PT2385). The predictive role of EPAS1 and the associated gene signature were analyzed using publicly available BC datasets.

Results: FOXA1 OE reprogrammed the FOXA1 cistrome in P cells to resemble that of the TamR cells. The FOXA1 cistrome was significantly correlated with the deposition of H3K27ac in TamR vs. P cells (P<2.2e-16). Similarly, the differentially expressed genes in TamR vs. P cells were enriched for FOXA1 binding at enhancers demarcated by H3K27ac (P=8e-125). The FOXA1-CGS was linked to multiple metastasis-related GO terms including “hypoxia response”, enriched for the cancer secretome gene set (P=4.1e-16), and highly represented in the Endo-R transcriptome across our multiple cell models (MCF7, 600MPE, and CAMA1) (P<0.01). Integrative analysis of H3K27ac-defined super-enhancers (SEs) and altered cistrome/transcriptome upon High-FOXA1 nominated EPAS1, a hypoxia-inducible transcription factor (TF), as a top candidate of SE-activated TFs amplifying High-FOXA1 signaling. EPAS1 blockade markedly repressed the secretome genes (e.g., IL8 and S100P) and cell migration and invasion in TamR cells. Primary ER+ tumors (TCGA) with high EPAS1 are enriched for a cancer secretome gene set (P=3e-4). High EPAS1 predicts poor distant metastasis-free survival in ER+ BC treated with endocrine therapy (P=.034).

Conclusions: High-FOXA1 induces transcriptional reprogramming by coordinating histone enhancer marks to activate EPAS1 via an SE mechanism, which in turn mediates transcriptional reprogramming, partly via inducing a pro-metastatic secretome, to promote Endo-R and metastasis. Targeting the High-FOXA1/EPAS1 axis to block transcriptional reprogramming may offer a new therapeutic strategy to prevent and treat Endo-R metastatic ER+ BC.

Citation Format: Fu X, Pereira R, De Angelis C, Veeraraghavan J, Shea MJ, Nanda S, Feng Q, Jeselsohn R, O'Malley BW, Brown M, Osborne CK, Schiff R. Hyperactive FOXA1 activates super-enhancer-engaged HIF2α/EPAS1 to promote endocrine-resistant metastatic ER-positive breast cancer [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 P4-04-03.

Abstract P5-21-02: Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies

Background:

Abemaciclib is an oral, selective inhibitor of cyclin-dependent kinases 4 & 6 that is dosed on a twice daily continuous schedule. In patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC), abemaciclib has demonstrated clinical efficacy with a tolerable safety profile when administered as monotherapy in MONARCH 1 (NCT02102490), in combination with fulvestrant in MONARCH 2 (NCT02107703), and in combination with non-steroidal aromatase inhibitors (NSAI) in MONARCH 3 (NCT02246621). Inducing tumor response and delaying disease progression is of critical need in pts with liver metastases (mets).

Methods:

An exploratory subgroup analysis was conducted in pts with liver mets at baseline across the MONARCH 1, 2, and 3 studies. All pts had HR+, HER2- ABC. The primary endpoint of MONARCH 1 was objective response rate (ORR), and the primary endpoint of MONARCH 2 and 3 was investigator-assessed progression-free survival (PFS). Analysis methods for these endpoints were previously described. Key enrollment criteria and dosing information are listed in Table 1.

Table 1. Eligibility criteria and dosing information for the MONARCH 1, 2, and 3 studiesKey enrollment criteriaMONARCH 1MONARCH 2MONARCH 3Prior endocrine therapyProgressed on or after ETProgressed while receiving adjuvant or first-line ET, or ≤ 12 months from the end of adjuvant ETET naïve or disease relapse >12 months after (neo)adjuvant ETChemotherapy regimens in advanced setting1 or 200Visceral crisisNo restrictionNot permittedNot permittedDose and Schedule   abemaciclib200 mg, twice daily, continuous150 mg1, twice daily, continuous150 mg, twice daily, continuousfulvestrant-500 mg, per label-anastrozole2--1 mg, dailyletrozole2--2.5 mg, daily1post-amendment; 2physician's choice of NSAI (anastrozole or letrozole); ET: endocrine therapy

Results:

Efficacy results of pts with liver mets are described in Table 2. The most frequent adverse events observed in pts with liver mets in MONARCH 1 were diarrhea, nausea, and fatigue and in the abemaciclib arms of MONARCH 2 and 3 were diarrhea, neutropenia, and nausea.

Table 2. PFS and response rates of pts with liver mets in MONARCH 1, 2, and 3 MONARCH 1MONARCH 2 abemaciclib armMONARCH 2 placebo armMONARCH 3 abemaciclib armMONARCH 3 placebo armPts with liver mets, n93115594830PFS, HR (95% CI)N/A.45 (.31, .64).47 (.25, .87)Median PFS, months5.611.63.115.07.2ORR, n (%)20 (21.5)54 (47.0)9 (15.3)26 (54.2)6 (20.0)CBR, n (%)39 (41.9)77 (67.0)21 (35.6)32 (66.7)12 (40.0)CBR: clinical benefit rate (complete response [CR] + partial response [PR] + stable disease ≥6 months); HR: hazard ratio; ORR: objective response rate (CR+PR); PFS: progression-free survival; pts: patients

Conclusions:

The results suggest that the combination of abemaciclib and endocrine therapy was an effective treatment option in pts with liver metastases, a population deriving modest benefit from single-agent endocrine therapy. Tolerability results were generally consistent with the safety populations previously reported for each study.

Citation Format: Di Leo A, Dickler M, Sledge GW, Toi M, Forrester T, Nanda S, Koustenis A, Bourayou N, Johnston S. Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies [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 P5-21-02.

Patterns of Biomarkers in Cord Blood During Pregnancy and Preeclampsia

BACKGROUND

Umbilical cord blood (UCB) is in contact with all the fetal tissues and can reflect the state of fetus and UCB can be compared with maternal blood. Inflammatory, metabolic and immunological disorders during pregnancy can affect the environment in which the fetus is developing and may produce various alterations.

OBJECTIVE

To analyze different biochemical parameters in maternal venous blood and new born umbilical cord blood from healthy normotensive pregnant and preeclamptic women.

MATERIALS AND METHODS

Homocysteine, folate, B12, heme oxygenase-1 (HO-1), endoglin, leptin, cholinesterase, IGF-1, Apo A, lipoproteins, TSH, fT3, fT4 were analyzed in maternal sera and venous umbilical cord sera of newborns of twenty five preeclamptics (group II) and twenty five normotensive pregnant women (group I). Homocysteine, folic acid, vitamin B12, Apo A I & II, TSH, fT3, fT4 levels were estimated by competitive immunoassay using direct chemiluminiscence technology. Heme oxygenase-1 (HO-1), endoglin, leptin, cholinesterase, IGF-1 were analyzed by ELISA.

RESULTS

Maternal and cord blood levels of homocysteine, folic acid, lipid profile (namely, total cholesterol, triglycerides, LDL-C, VLDL-C and HDL-C), TSH, heme oxygenase 1, were higher in preeclamptic women as compared to normotensive pregnant women. Endoglin levels were significantly lower in cord blood of preeclamptic mother as compared to normotensive mothers. Serum and cord blood vitamin B12, Apo A-I and Apo B l, cholinesterase, leptin levels, IGF-I were lower in preeclamptic women as compared to normotensive pregnant.

CONCLUSION

Findings of the present study suggest that biochemical alterations occur in mothers and fetuses and modifications of uterine environment (in terms of thyroxine and folate and vitamin B12 supplementation) can be of help.