The Impact of Medicaid Expansion Under the Affordable Care Act on the Gap Between American Indians and Whites in Breast Cancer Management and Prognosis

BACKGROUND

Breast cancer (BC) death rates in the USA have not significantly declined for American Indians (AIs) in comparison to Whites. Our objective was to determine whether Medicaid Expansion as part of the Affordable Care Act led to improved BC outcomes for AIs relative to Whites.

PATIENTS AND METHODS

Using the National Cancer Database, we conducted a retrospective cohort study. Included were BC patients who were AI and White; 40 to 64 years of age; diagnosed in 2009 to 2016; lived in states that expanded Medicaid in January 2014, and states that did not expand Medicaid. Our outcomes were stage at diagnosis, insurance status, timely treatment, and 3-year mortality.

RESULTS

There were 359,484 newly diagnosed BC patients, 99.49% White, 0.51% AI. Uninsured rates declined more in the expansion states than in the nonexpansion states (OR = 0.44, 95% CI: 0.15-0.97, P < 0.001). Lower rates of Stage I BC diagnosis was found in AIs compared to Whites (46.58% vs. 55.33%, P < .001); these differential rates did not change after Medicaid expansion. Rates of definitive treatment initiation within 30 days of diagnosis declined after Medicaid expansion (P < .001); there was a smaller decline in the expansion states (OR 1.118, 95% CI: 1.09, 1.15, P < .001). Three year mortality was not different between expansion and nonexpansion states post Medicaid expansion.

CONCLUSIONS

In newly diagnosed BCs, uninsured rates declined more in the states that expanded Medicaid in January 2014. Timely treatment post Medicaid expansion declined less in states that expanded Medicaid. There was no differential benefit of Medicaid expansion in the 2 races.

Differences in Breast Cancers Among American Indian/Alaska Native and non-Hispanic Whites in the USA

IMPORTANCE

Breast cancer (BC) death rates have not improved for American Indian/Alaska Native (AI/AN) women, whereas, it has significantly decreased for non-Hispanic White (White) women.

OBJECTIVE

Delineate the differences in patient and tumor characteristics among AI/AN and Whites with BC, and its impact on age and stage at diagnosis as well as overall survival (OS).

METHODS

Hospital-based, cohort study using the National Cancer Database to identify female AI/AN and Whites diagnosed with BC between the years 2004 and 2016.

RESULTS

BC in 6866 AI/AN (0.3%) and 1,987,324 Whites (99.7%) were studied. The median age at diagnosis was 58 for AI/AN and 62 for Whites. AI BC patients traveled double the distance for treatment, lived in lower median income zip codes, had a higher percentage of uninsured, higher comorbidities, lower percentage of Stage 0/I, larger tumor size, greater number of positive lymph nodes, higher proportion of triple negative and HER2-positive BC than Whites. All the above comparisons were significant, p<0.001. Association between patient/tumor characteristics with age and stage at diagnosis was not significantly different between AI/AN and Whites. Unadjusted OS was worse for AI/AN as compared to Whites (HR=1.07, 95% CI=1.01-1.14, p=0.023). After adjustment of all covariates, OS was not different (HR=1.038, 95%CI=0.902-1.195, p=0.601).

CONCLUSION

There were significant differences in patient/tumor characteristics among AI/AN and White BC which adversely impacted OS in AI/AN. However, when adjusted for various covariates, the survival was similar, suggesting that the worse survival in AI/AN is mostly the impact of known biological, socio-economic, and environmental determinants of health.

Polyclonal Antibodies Derived from Transchromosomic Bovines Vaccinated with the Recombinant F1-V Vaccine Increase Bacterial Opsonization In Vitro and Protect Mice from Pneumonic Plague

Plague is an ancient disease that continues to be of concern to both the public health and biodefense research communities. Pneumonic plague is caused by hematogenous spread of Yersinia pestis bacteria from a ruptured bubo to the lungs or by directly inhaling aerosolized bacteria. The fatality rate associated with pneumonic plague is significant unless effective antibiotic therapy is initiated soon after an early and accurate diagnosis is made. As with all bacterial pathogens, drug resistance is a primary concern when developing strategies to combat these Yersinia pestis infections in the future. While there has been significant progress in vaccine development, no FDA-approved vaccine strategy exists; thus, other medical countermeasures are needed. Antibody treatment has been shown to be effective in animal models of plague. We produced fully human polyclonal antibodies in transchromosomic bovines vaccinated with the recombinant F1-V plague vaccine. The resulting human antibodies opsonized Y. pestis bacteria in the presence of RAW264.7 cells and afforded significant protection to BALB/c mice after exposure to aerosolized Y. pestis. These data demonstrate the utility of this technology to produce large quantities of non-immunogenic anti-plague human antibodies to prevent or possibly treat pneumonic plague in human.

OUP accepted manuscript

Passive antibody immunotherapeutics directed against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are promising countermeasures for protection and treatment of coronavirus disease 2019 (COVID-19). SARS-CoV-2 variants of concern (VOCs) and variants of interest (VOIs) can impact the clinical efficacy of immunotherapeutics. A fully human polyclonal antibody immunotherapeutic purified from plasma of transchromosomic (Tc) bovines hyperimmunized with SARS-CoV-2 WA-1 spike (SAB-185) is being assessed for efficacy in a phase 2/3 clinical trial when different circulating SARS-CoV-2 variants predominated. We evaluated antibody binding, avidity maturation, and SARS-CoV-2 VOCs/VOIs virus-neutralizing capacity of convalescent plasma compared with different lots of SAB-185 and individual Tc bovine sera sequentially obtained after each vaccination against Alpha, Epsilon, Iota, Gamma, Beta, Kappa, and Delta variants. In contrast to convalescent plasma, sera and SAB-185 derived from hyperimmunized Tc bovines demonstrated higher antibody avidity and more potent cross-neutralizing activity of VOCs/VOIs. Thus, SAB-185 is a potential promising therapeutic candidate for the treatment of patients infected with SARS-CoV-2 variants.

Human immunoglobulin from transchromosomic bovines hyperimmunized with SARS-CoV-2 spike antigen efficiently neutralizes viral variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with amino-acid substitutions and deletions in spike protein (S) can reduce the effectiveness of monoclonal antibodies (mAbs) and may compromise immunity induced by vaccines. We report a polyclonal, fully human, anti-SARS-CoV-2 immunoglobulin produced in transchromosomic bovines (Tc-hIgG-SARS-CoV-2) hyperimmunized with two doses of plasmid DNA encoding the SARS-CoV-2 Wuhan strain S gene, followed by repeated immunization with S protein purified from insect cells. The resulting Tc-hIgG-SARS-CoV-2, termed SAB-185, efficiently neutralizes SARS-CoV-2, and vesicular stomatitis virus (VSV) SARS-CoV-2 chimeras in vitro. Neutralization potency was retained for S variants including S477N, E484K, and N501Y, substitutions present in recent variants of concern. In contrast to the ease of selection of escape variants with mAbs and convalescent human plasma, we were unable to isolate VSV-SARS-CoV-2 mutants resistant to Tc-hIgG-SARS-CoV-2 neutralization. This fully human immunoglobulin that potently inhibits SARS-CoV-2 infection may provide an effective therapeutic to combat COVID-19.

Abstract SS1-08: Did Medicaid expansion under the Affordable Care Act narrow the gap between American Indians and Whites on breast cancer management and prognosis?

Prior studies have shown that over a span of 20 years (1990-2009), breast cancer death rates in the U.S. have not significantly declined for American Indians (AIs) in comparison to the White population. Health insurance coverage contributes independently and positively to the health of individuals through the receipt of adequate preventive services and care for diseases such as breast cancer. To this end, the 2010 Medicaid Expansion as part of the Affordable Care Act (ACA) has extended the health insurance coverage eligibility to adults with incomes up to 133 percent of the federal poverty level. In this study, we examined whether Medicaid expansion resulted in the improvement of breast cancer management and prognosis for AIs relative to the White population. Methods: We abstracted information from the National Cancer Data Base (NCDB) for AI and White breast cancer patients diagnosed between the years 2004-2016 who lived in states that expanded Medicaid in January 2014, and those that did not expand Medicaid. Data on age, race, stage at diagnosis, insurance status, definitive treatment initiation within 30 days of diagnosis, and 3-year mortality was analyzed. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multiple logistic regression to determine the impact of race (White vs. AI), Medicaid expansion status, and pre- vs. post-expansion periods on breast cancer management and prognosis. All p-values are two-sided. Analyses were performed using SPSS software V25. Results: There were 1,465,103 newly diagnosed White and AI breast cancers between the years 2004-2016; 99.7% were Whites and 0.3% were AIs. Of these, 46.9% resided in states that expanded Medicaid in January 2014 and 53.1% in states that did not expand Medicaid; 73.8% were diagnosed in the pre-expansion period (January 2004-December 2013) and 26.2% were diagnosed in the post-expansion period (January 2014-December 2016). There was an increase in the proportion of early stage (0, 1) breast cancer diagnosis in the period 2014-2016 as compared to the period 2004-2013 (OR=1.434, 95% CI:1.159- 1.775; p = 0.001), and this increase was significantly greater for AIs than for Whites (6% vs 3%; p=0.027) in both expansion and non-expansion states. An independent chi-square analysis of AIs found that there was a significant increase of the early stage diagnosis in the expansion states during the post-expansion period (p=0.001). The proportion of uninsured declined in the period 2014-2016 as compared to the period prior (OR=0.331, 95% CI: 0.129- 0.850; p=0.022), more so in the expansion states (decrease from 1.4% to 0.8%), vs. non expansion states (decrease from 2.3% to 2.2%) (p=0.019); no difference in decline was found between Whites and AIs. The probability of getting first definitive treatment within 30 days of diagnosis declined more in states without Medicaid expansion (decrease from 54% to 43%) than in states with Medicaid expansion (decrease from 50% to 43%) (p=0.028) for both AIs and Whites; and the decline was more in Whites (decrease from 55% to 44%) than in AIs (decrease from 49% to 42%) from pre-expansion period to post-expansion period (p=0.018). The 3-year mortality rates did not show any significant relationship to race, expansion status, or the pre- or post-expansion periods. Conclusion: In patients newly diagnosed with breast cancer, the proportion of uninsured declined significantly with Medicaid expansion and the proportion of patients who received first definitive treatment within 30 days of diagnosis decreased significantly less in AIs and in states that expanded Medicaid under the Affordable Care Act. Medicaid expansion increased early breast cancer diagnosis in AIs; this effect was not seen in non-expansion states. Medicaid expansion did not affect 3-year mortality rate.

Citation Format: Anu G Gaba, Li Cao, Rebecca Renfrew, Kristi A Egland, DeAnn L Witte, Janet Wernisch, Ross Crosby. Did Medicaid expansion under the Affordable Care Act narrow the gap between American Indians and Whites on breast cancer management and prognosis? [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SS1-08.

SUSD2 expression correlates with decreased metastasis and increased survival in a high-grade serous ovarian cancer xenograft murine model

The cause of death among high-grade serous ovarian cancer (HGSOC) patients involves passive dissemination of cancer cells within the peritoneal cavity and subsequent implantation of cancer spheroids into adjacent organs. Sushi DomainContaining 2 (SUSD2) encodes a type I transmembrane protein containing several functional domains inherent to adhesion molecules. Previous studies using in vitro methods have indicated that SUSD2 functions as a tumor suppressor in several cancers, including HGSOC. In this study, we generated a HGSOC xenograft mouse model to investigate SUSD2 expression in the context of HGSOC late-stage metastasis and overall survival. OVCAR3 cells with knock-down expression of SUSD2 (OVCAR3 SUSD2-KD) or endogenous expression of SUSD2 (OVCAR3-Non-Targeting (NT)) were injected into the peritoneal cavity of athymic nude mice. Immunohistochemistry analysis was utilized to identify infiltrating cancer cells and metastatic tumors in mouse ovaries, pancreas, spleen, omentum and liver. OVCAR3-NT mice developed significantly less cancer cell infiltrate and tumors in their pancreas and omentum compared to OVCAR3 SUSD2-KD mice. Furthermore, OVCAR3-NT mice displayed a longer median survival when compared to OVCAR3 SUSD2-KD mice (175 days and 185.5 days, respectively; p-value 0.0159). Altogether, the findings generated through the preclinical mouse model suggest that increased SUSD2 expression in HGSOC impedes in vivo metastasis to pancreas and omentum. These results correlate to longer median survival and prove to be consistent with previous findings showing prolonged survival of HGSOC patients with high SUSD2-expressing primary tumors.

SUSD2 Proteolytic Cleavage Requires the GDPH Sequence and Inter-Fragment Disulfide Bonds for Surface Presentation of Galectin-1 on Breast Cancer Cells

Galectin-1 (Gal-1) is a 14 kDa protein that has been well characterized for promoting cancer metastasis and tumor immune evasion. By localizing to the cancer cell surface, Gal-1 induces T cell apoptosis through binding T cell surface receptors. The transmembrane protein, Sushi Domain Containing 2 (SUSD2), has been previously shown to be required for Gal-1 surface presentation in breast cancer cells. Western immunoblot analysis revealed that SUSD2 is cleaved into two fragments. However, the significance of this cleavage for Gal-1 surface localization has not been investigated. To define the location of cleavage, a mutagenesis analysis of SUSD2 was performed. Our studies demonstrated that SUSD2 is cleaved at its glycine-aspartic acid-proline-histidine (GDPH) amino acid sequence. Generation of a noncleavable SUSD2 mutant (GDPH∆-SUSD2) showed that SUSD2 cleavage was required for SUSD2 and Gal-1 plasma membrane localization. Noncleavable cysteine mutants were also unable to present Gal-1 at the cell surface, further demonstrating that SUSD2 cleavage is required for Gal-1 surface presentation. Treatment with the serine protease inhibitor, Pefabloc SC, inhibited SUSD2 cleavage in a dose dependent manner, suggesting that SUSD2 is cleaved by a serine protease. Therefore, identification and inhibition of this protease may provide a new therapeutic tool for inhibiting SUSD2 and Gal-1's combined tumorigenic function in breast cancer.

Sushi Domain Containing 2 (SUSD2) inhibits platelet activation and binding to high-grade serous ovarian carcinoma cells

Platelets play a central role in primary hemostasis affecting tumor survival and metastases. Tumors induce platelets to aggregate and bind to the cancer cells, resulting in protection from immune surveillance and often leading to thrombocytosis. In ovarian cancer (OvCa), one-third of patients present with thrombocytosis, a diagnosis that correlates with shorter survival. SUSD2 (SUShi Domain containing 2), a type I transmembrane protein, shown to inhibit metastatic processes in high-grade serous ovarian carcinoma (HGSOC), is expressed on endothelial cells and thus may influence platelet reactivity. As such, we hypothesized that SUSD2 levels in ovarian cancer-derived cell lines influence platelet activation. We incubated OvCa non-targeting (NT) and SUSD2 knockdown (KD) cell lines with labeled platelets and quantified platelet binding, as well as GPIIb/IIIa integrin activation. The role of GPIIb/IIIa in tumor cell/platelet interaction was also examined by measuring cell-cell adhesion in the presence of eptifibatide. We found that platelets exposed to OvCa cells with low SUSD2 expression display increased tumor cell-platelet binding along with an increase in GPIIb/IIIa receptor activation. As such, platelet activation and binding to HGSOC cells was inversely correlated with the presence of SUSD2. This represents one of the first tumor proteins known to provide differential platelet interaction based on protein status.

Abstract P3-07-02: Inhibition of sushi domain containing 2 (SUSD2) cleavage prevents surface presentation of galectin-1 on breast cancer cells

Routinely used therapies are not adequate to treat the heterogeneity of breast cancer (BCa), and consequently, more therapeutic targets are desperately needed. Sushi Domain Containing 2 (SUSD2) is a type I transmembrane protein composed of functional domains inherent to adhesion molecules. SUSD2 is highly expressed in BCa but has minimal expression in other normal tissues. Using an in vivo syngeneic mouse model, the Egland lab demonstrated that mice with Susd2-expressing tumors showed increased tumor growth and decreased survival compared to vector controls. Interestingly, Susd2-expressing tumors contained 50% fewer infiltrating CD4 T cells when compared to vector control tumors. In vitro co-culture assays of MDA-MB-231 and Jurkat cells showed that MDA-MB-231-SUSD2 cells increased T cell death compared to MDA-MB-231-vector cells. Our preliminary experiments suggest that SUSD2 acts through the protein Galectin-1 (Gal-1) to achieve T cell killing. Gal-1 has been implicated as a major contributor to cancer immune evasion and angiogenesis. When Gal-1 is targeted by an inhibitory molecule, cancer progression is reduced. Surface presentation of Gal-1 by cancer cells was shown to be required for T cell killing. We have previously shown that localization of Gal-1 on the surface of cells is dependent on the presence of SUSD2; therefore, disrupting the SUSD2-Gal-1 interaction offers a potential new therapeutic strategy for BCa. Western immunoblot analysis using an anti-SUSD2 antibody against the C-terminus showed that SUSD2 runs as two bands, a 110kDa full-length band and a 60kDa fragment, suggesting that SUSD2 is cleaved. When antibodies against both the C-terminus and N-terminus of SUSD2 were used, three bands were observed: a full-length 110kDa band and fragment bands of 60kDa and 50kDa. The cleavage site and significance of this cleavage with respect to SUSD2 and Gal-1 interactions previously has not been investigated. Edman degradation was used to sequence the C-terminal SUSD2 fragment and determined that the cleavage site is within the Von Willebrand type D domain, between the aspartic acid and proline of the GDPH sequence. Deletion of the GDPH sequence showed a complete inhibition of SUSD2 cleavage. Furthermore, non-cleaved SUSD2 was unable to localize to the plasma membrane indicating that SUSD2 cleavage is important for cell surface presentation. Consistently, Gal-1 was not localized to the cell surface in MDA-MB-231 cells expressing the non-cleavable SUSD2 mutant. Our results indicate that SUSD2 cleavage is a processing step required for Gal-1 surface localization and inhibiting SUSD2 processing may be a viable targeting strategy. We are treating SUSD2-expressing BCa cells with protease inhibitors to identify the protease responsible for SUSD2 cleavage. The identification of this protease would provide a potential target for decreasing BCa tumorigenesis and increasing survival of BCa patients.

Citation Format: Patrick ME, Egland KA. Inhibition of sushi domain containing 2 (SUSD2) cleavage prevents surface presentation of galectin-1 on breast cancer cells [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 P3-07-02.

Longitudinal autoantibody responses against tumor-associated antigens decrease in breast cancer patients according to treatment modality

BACKGROUND

Metastatic breast cancer (BCa) is most often diagnosed months after completion of treatment of the primary tumor when a patient reports physical symptoms. Besides a physical examination, no other alternative recurrence screening method is recommended for routine follow-up care. Detection of autoantibodies against tumor-associated antigens (TAAs) has demonstrated promise for distinguishing healthy women from patients diagnosed with primary BCa. However, it is unknown what changes occur to patient autoantibody levels during and after treatment.

METHODS

Three serial blood draws were collected from 200 BCa patients: before treatment, 6 and 12 months after surgery. Patients were categorized according to treatment regimen, including surgery, chemotherapy, radiation, trastuzumab and hormonal therapies. The longitudinal samples were assayed for autoantibody responses against 32 conformation-carrying TAAs using a Luminex multiplex bead assay.

RESULTS

The treatment modality groups that had the greatest decrease in autoantibody response levels were radiation + hormonal therapy; radiation + chemotherapy; and radiation + hormonal therapy + chemotherapy. For these three treatment groups, autoantibody responses against 9 TAAs (A1AT, ANGPTL4, CAPC, CST2, DKK1, GFRA1, GRN, LGALS3 and LRP10) were significantly reduced at 12 months after surgery compared to before treatment. One TAA, GRP78, had a significantly increased autoantibody response after 12 months.

CONCLUSIONS

Single treatment regimens alone did not significantly alter autoantibodies levels against the studied TAAs. Radiation treatment was the common denominator of the three most affected groups for significant changes in autoantibody response levels.

Abstract POSTER-BIOL-1345: SUSD2 inhibits spheroids from breaching the mesothelium: a mechanism for increased longevity of patients with SUSD2-expressing high-grade ovarian serous carcinoma

The cause of death among the majority of epithelial ovarian cancer (EOC) patients involves metastasis and subsequent invasion of cancer cells into organs enclosed and adjacent to the abdominal cavity, which can lead to deadly health complications such as bowel obstruction. Thus, it is important to identify the factors that contribute to metastasis and invasion including those that facilitate adhesion to the mesothelium. The anatomical location of the ovary and the fallopian tube within the peritoneal cavity facilitates metastasis of ovarian cancer without involvement of the vasculature. EOC cells exfoliate from the fallopian tube or ovary, disseminate within the peritoneal cavity as free-floating single cells or spheroids and invade mesothelium-covered organs including the bowel.

To identify potential immunotherapy targets for epithelial cancers, we generated a cDNA library enriched with genes encoding membrane and secreted proteins that are highly expressed in cancer with minimal expression in normal essential tissues. From this library we identified Sushi Domain Containing 2 (SUSD2), a type I transmembrane protein that localizes to the cell surface and contains several functional domains inherent to adhesion molecules. To determine the expression pattern of SUSD2 in normal and carcinoma ovarian tissues, an immunohistochemical analysis was performed on ovarian tissue samples from patients using an anti-SUSD2 antibody. Weak to no staining was observed in normal epithelial cells. In contrast, various intensities of positive staining for SUSD2 were observed in several types of EOC, including serous, mucinous, endometrioid and transitional adenocarcinomas. A high-grade serous ovarian carcinoma (HGSOC) tissue microarray containing samples from 128 patients was stained with an anti-SUSD2 antibody. A pathologist scored the intensity of SUSD2 staining, and results were correlated with patient outcome. A Kaplan-Meier curve indicated a significant separation for patients with weak SUSD2 staining, median survival 31.7 months, versus patients with strong SUSD2 staining, median survival 49.1 months (p-value = 0.0083). This data suggests that low SUSD2 levels in HGSOC tumors are associated with a poorer prognosis for the patient. To investigate the role of SUSD2 in HGSOC, stable SUSD2 knock-down (KD) and non-targeting (NT) OVCAR3 cell lines were generated. Boyden chamber and wound healing assays were used to assess the effect of SUSD2 on migration. OVCAR3 SUSD2-KD cells migrated at significantly higher rates than the OVCAR3-NT cells suggesting that the presence of SUSD2 in OVCAR3 cells inhibits cell migration. In addition, attenuation of SUSD2 levels in OVCAR3 cells significantly increased mesothelial clearance. Altogether, our findings indicate that SUSD2 negatively impacts the ability of OVCAR3 cells to breach the mesothelium, which defines a mechanism for the increased longevity of patients with SUSD2-expressing HGSOC.

Citation Format: Jordan N. Sheets, Marcin Iwanicki, Joyce Liu, Ronny Drapkin, Kristi A. Egland. SUSD2 inhibits spheroids from breaching the mesothelium: a mechanism for increased longevity of patients with SUSD2-expressing high-grade ovarian serous carcinoma [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-BIOL-1345.

Classifying patients for breast cancer by detection of autoantibodies against a panel of conformation-carrying antigens

Patients with breast cancer elicit an autoantibody response against cancer proteins, which reflects and amplifies the cellular changes associated with tumorigenesis. Detection of autoantibodies in plasma may provide a minimally invasive mechanism for early detection of breast cancer. To identify cancer proteins that elicit a humoral response, we generated a cDNA library enriched for breast cancer genes that encode membrane and secreted proteins, which are more likely to induce an antibody response compared with intracellular proteins. To generate conformation-carrying antigens that are efficiently recognized by patients' antibodies, a eukaryotic expression strategy was established. Plasma from 200 patients with breast cancer and 200 age-matched healthy controls were measured for autoantibody activity against 20 different antigens designed to have conformational epitopes using ELISA. A conditional logistic regression model was used to select a combination of autoantibody responses against the 20 different antigens to classify patients with breast cancer from healthy controls. The best combination included ANGPTL4, DKK1, GAL1, MUC1, GFRA1, GRN, and LRRC15; however, autoantibody responses against GFRA1, GRN, and LRRC15 were inversely correlated with breast cancer. When the autoantibody responses against the 7 antigens were added to the base model, including age, BMI, race and current smoking status, the assay had the following diagnostic capabilities: c-stat (95% CI), 0.82 (0.78-0.86); sensitivity, 73%; specificity, 76%; and positive likelihood ratio (95% CI), 3.04 (2.34-3.94). The model was calibrated across risk deciles (Hosmer-Lemeshow, P = 0.13) and performed well in specific subtypes of breast cancer including estrogen receptor positive, HER-2 positive, invasive, in situ and tumor sizes >1 cm.

Abstract A71: Expression of Sushi Domain Containing 2 (SUSD2) in high-grade ovarian serous carcinoma correlated with increased longevity of patients

Despite research in therapeutic strategies, ovarian cancer (OvCa) remains the most lethal gynecologic malignancy. The anatomical location of the ovaries within the peritoneal cavity facilitates metastasis by allowing tumor cells sloughed from the main tumor on the ovary to bind to the peritoneum or organs within the peritoneal cavity. These tumor cells are released from the main tumor either as single cells or as spheroids, the latter of which have been shown to be more effective at metastasizing and invading into the mesothelial lining. To identify novel tumor markers and therapeutic targets for epithelial cancers, a cDNA library enriched for cancer genes that encode membrane and secreted proteins was generated. The 18th most abundant gene represented in this library was Sushi Domain Containing 2 (SUSD2), which encodes an 822 amino acid membrane surface protein. To begin defining the role of SUSD2 in OvCa, stable SUSD2-expressing and vector control A2780 cell lines were generated. To examine whether SUSD2 affects the growth of OvCa cells, cellular proliferation assays were performed. There was no significant difference in growth rates with SUSD2 over-expression compared to the vector control cell lines. A Boyden chamber assay was performed to analyze the effect of SUSD2 on cell migration. A2780-SUSD2 cell lines and vector-only controls were plated on membranes and allowed to migrate toward a chemoattractant in a lower chamber. SUSD2 over-expression significantly increased migration by greater than 2-fold. In addition, a scratch wound-healing assay was performed, and after 24 hours the A2780-SUSD2 cell line had 2-fold more cells within the wound compared to the A2780-vector control cells (P&lt;0.05). Consistently, agarose beads containing either A2780-SUSD2 or vector cells were grown in chemoattractant containing media. The distance the escaped cells traveled from the bead was measured. A2780-SUSD2 cells traveled farther away from the bead compared to the vector control (717 μm compared to 125 μm, respectively, P&lt;0.05). Spheroid-forming ability was analyzed, and A2780-SUSD2 cells formed smaller and looser spheroids (length and width average of 933 μm) compared to A2780-vector control cells (length and width average of 1237 μm, P=0.025). To correlate OvCa patient outcome with the presence of SUSD2 in the corresponding tumor, a tissue microarray containing high-grade ovarian serous carcinoma core samples from 128 patients was stained with an anti-SUSD2 antibody. The intensity of SUSD2 staining was scored by a pathologist, and results were correlated with patient outcome. A Kaplan-Meier curve indicated a significant separation for patients with low SUSD2 levels, median survival 31.7 months, versus patients with strong SUSD2 staining, median survival 49.1 months (P=0.0083). This data suggests that low SUSD2 levels in OvCa tumors are associated with a poorer prognosis for the patient. Our in vitro assays indicate that expression of SUSD2 in A2780 cells increased the ability of the cells to migrate and caused the formation of smaller spheroids. Because spheroids are better able to resist chemotherapy and invade the mesothelium, the decreased spheroid size of SUSD2-expressing cells may allow for a better patient prognosis.

Citation Format: Jennifer A. A. Gubbels, Elizabeth M. Hultgren, Jessica Johnson, Emily Johnson, Jeffrey Sachs, Michelle S. Hirsch, Joyce Liu, Ronny Drapkin, Kristi A. Egland. Expression of Sushi Domain Containing 2 (SUSD2) in high-grade ovarian serous carcinoma correlated with increased longevity of patients. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A71.

Abstract P1-05-16: Sushi Domain Containing 2 (SUSD2): a plasma membrane protein that increases immune evasion in breast tumorigenesis

Routinely used therapies are not adequate to treat the heterogeneity of breast cancer, and consequently, more therapeutic targets are desperately needed. To identify novel targets, we generated a breast cancer cDNA library enriched for breast cancer genes that encode membrane and secreted proteins. From this library we identified SUSD2 (Sushi Domain Containing 2), which encodes an 822 amino acid protein containing a transmembrane domain and functional domains inherent to adhesion molecules. Previous studies describe the mouse homolog, mSVS-1, but there are no studies on the human gene associated with breast cancer.

Reverse-Transcriptase PCR analysis using total RNA from frozen breast cancer samples showed that SUSD2 is expressed in 19 of 24 breast tumors. Immunohistochemistry (IHC) analysis was performed on human breast tissues using an anti-SUSD2 antibody. IHC showed weak or no expression of SUSD2 in normal epithelial cells, with the endothelial lining of vessels staining positive for SUSD2. However, staining was observed in pathological breast lesions and in lobular and ductal carcinomas.

To explore the role of SUSD2 in breast tumorigenesis, we performed in vitro analyses of stable cell lines generated to over-express SUSD2. Our studies indicate that over-expression of SUSD2 increases the invasion of breast cancer cells through Matrigel and adhesion to fibronectin, an extracellular matrix protein. Additionally, contact between peripheral blood mononuclear cells (PBMCs) and breast cancer cells that express SUSD2 leads to diminished secretion of chemotactic cytokines and increased secretion of angiogenic cytokines compared to the empty-vector control. A similar co-culture experiment with Jurkat T cells showed increased induction of T cell apoptosis when cultured with cancer cells expressing SUSD2.

Using an in vivo model with immunocompetent mice, we observed increased tumor growth and decreased survival in mice with mammary tumors expressing mSVS-1. Interestingly, increased tumor growth rate was not due to higher proliferative rates of the cells, as the Ki67 index was similar for all tumors. IHC staining with an anti-CD31 antibody revealed disordered and tortuous microvasculature in tumors expressing mSVS-1. We also characterized the population of lymphocytes in the blood, spleen and tumors of the mice as a measure of the immune response. While proportions of CD4 and CD8 cells were unchanged in the spleen and blood samples, we found significantly fewer CD4 tumor infiltrating lymphocytes in mice with tumors expressing mSVS-1.

SUSD2 interacts with Galectin-1 (Gal-1), a 14-kDa secreted protein that is synthesized by carcinoma cells and promotes tumor immune evasion, angiogenesis and metastasis. Several previous studies suggest that cellular localization of Gal-1 is essential for its multiple roles in tumorigenesis. Interestingly, cell surface localization of Gal-1 was observed only in cell lines expressing SUSD2 but not the empty-vector control. Because the localization of Gal-1 on the surface of cells is dependent on the presence of SUSD2, using SUSD2 as a therapeutic target may disrupt this interaction and inhibit events required for tumorigenesis.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-05-16.

Multiple functions of sushi domain containing 2 (SUSD2) in breast tumorigenesis

Routinely used therapies are not adequate to treat the heterogeneity of breast cancer, and consequently, more therapeutic targets are desperately needed. To identify novel targets, we generated a breast cancer cDNA library enriched for genes that encode membrane and secreted proteins. From this library we identified SUSD2 (Sushi Domain Containing 2), which encodes an 822-amino acid protein containing a transmembrane domain and functional domains inherent to adhesion molecules. Previous studies describe the mouse homolog, Susd2, but there are no studies on the human gene associated with breast cancer. Immunohistochemical analysis of human breast tissues showed weak or no expression of SUSD2 in normal epithelial cells, with the endothelial lining of vessels staining positive for SUSD2. However, staining was observed in pathologic breast lesions and in lobular and ductal carcinomas. SUSD2 interacts with galectin-1 (Gal-1), a 14-kDa secreted protein that is synthesized by carcinoma cells and promotes tumor immune evasion, angiogenesis, and metastasis. Interestingly, we found that localization of Gal-1 on the surface of cells is dependent on the presence of SUSD2. Various phenotype assays indicate that SUSD2 increases the invasion of breast cancer cells and contributes to a potential immune evasion mechanism through induction of apoptosis of Jurkat T cells. Using a syngeneic mouse model, we observed accelerated tumor formation and decreased survival in mice with tumors expressing Susd2. We found significantly fewer CD4 tumor infiltrating lymphocytes in mice with tumors expressing Susd2. Together, our findings provide evidence that SUSD2 may represent a promising therapeutic target for breast cancer.

Abstract 3054: Sushi domain containing 2 (SUSD2): A plasma membrane protein on breast cancer cells that interacts with galectin-1

Tumor-specific immunotherapies use the binding specificity of antibodies to target and kill cancer cells. For example, the anti-ErbB2 monoclonal antibody, TrastuzuMab (or Herceptin), has shown clinical efficacy for the treatment of metastatic breast cancers with ErbB2 overexpression. Because only 25-30% of human breast cancers overexpress ErbB2, there is a great need for the identification of more breast tumor-specific immunotherapy targets that are present on cancer cells but are minimally expressed in normal essential tissues.

To identify novel immunotherapy targets, we generated a cDNA library enriched for breast cancer genes that encode membrane and secreted proteins. From this library we identified a new breast cancer gene, SUSD2 (Sushi Domain Containing 2), which encodes an 820 amino acid protein containing a transmembrane domain and several functional domains inherent to adhesion molecules. Previous studies describe the mouse homolog, mSVS-1, but there are no previous studies on the human gene associated with breast cancer. Reverse-Transcriptase PCR analysis using total RNA from frozen breast cancer samples and various cancer cell lines showed that SUSD2 is expressed in 19 of 24 breast tumors and all but one cancer cell line. Confocal microscopy revealed that SUSD2 localizes to the plasma membrane of breast cancer cells. Paraffin-embedded blocks of tissue were collected from bilateral mastectomies, with one block containing tumor tissue and one from the contralateral normal breast. Immunohistochemistry (IHC) analysis was performed using an anti-SUSD2 antibody. IHC showed weak or no expression of SUSD2 in normal epithelial cells, with the endothelial lining of vessels staining positive for SUSD2. However, strong staining was observed in various pathological breast lesions and in lobular and ductal carcinomas.

To identify proteins that interact with SUSD2, immunoprecipitation followed by western immunoblot analysis, confocal microscopy, and flow cytometry were used. All methods confirmed that SUSD2 interacts with Galectin-1, a 14-kDa protein that is synthesized by carcinoma cells and secreted into the stroma surrounding tumors. Galectin-1 has been shown to contribute to tumor evasion of immune responses by inducing apoptosis of activated T cells, while resting T cells also bind to Galectin-1, but do not undergo apoptosis. A stable MDA-MB-231 cell line overexpressing SUSD2 was generated. In plate-based cell adhesion assays, MDA-MB-231 (SUSD2) cells bound with higher affinity to peripheral blood mononuclear cells (PBMCs), yet were more protected from PBMC-mediated killing compared to the vector control cell line.

Future studies will explore the relationship of SUSD2 and Galectin-1 in breast cancer, and their role in immune escape. Because of its location on the plasma membrane and its high expression in breast cancer, SUSD2 may be used as a possible therapeutic target.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3054. doi:10.1158/1538-7445.AM2011-3054

Pathways to personalized medicine for breast and prostate cancers: emerging diagnostic methods and prognostic biomarkers

Early and personal diagnosis to breast a prostate cancer is crucial for optimizing treatments leading to long-term patient survival. Once cancer metastasizes from the breast or prostate to other tissues of the body, therapies are limited, and there is no cure for the diseases. Currently used screening modalities for breast and prostate cancers have limitations. Routine screening for breast cancer includes clinical breast exams and mammograms. Improvements in imaging techniques, such as magnetic resonance, ultrasound, digital breast tomosynthesis and ductography are being explored as adjuncts to mammography. A new approach to breast cancer screening involves the detection of abnormalities at the cellular level and uses various means to collect cellular material from the ductal system, including nipple aspirate fluid, breast ductal lavage, fiberoptic ductoscopy and random periareolar fine needle aspiration. Current screening methods for prostate cancer include digital rectal exam and serum PSA levels. However, these methods offer low sensitivity and specificity and do not allow differentiation between significant- and minimal-risk cancers. New approaches to prostate cancer screening involve different calculations using PSA, as well as molecular urine tests. With the recent advances in microarray technologies and whole-genome sequencing of tumors, the identification of specific biomarkers for diagnosis and prognosis, as well as new therapeutic targets, is quickly paving the way for personalized medicine. In the future, routine patient care will include using the molecular signature of a patient's disease to guide treatment.

High expression of a cytokeratin-associated protein in many cancers

We have described previously a cDNA library made from membrane-bound polysomal mRNA prepared from breast and prostate cancer cell lines. The library is highly enriched for cDNAs encoding membrane proteins, secreted proteins, and cytokeratins. To characterize this library, 25,277 cDNA clones were sequenced and aligned with various databases; 1,439 clones did not align with known genes. From this set of clones we identified a previously uncharacterized gene encoding a 334-aa protein. Although protein structural motif prediction programs indicate that the gene encodes a membrane protein comprising a signal sequence, a series of leucine-rich repeats, and a single transmembrane domain with a cytoplasmic tail, confocal microscopy of MCF7 breast cancer cells demonstrates that the protein is not directly associated with the plasma membrane or intracellular membranes but instead colocalizes with intermediate filaments and cytokeratins within the cell. Immunofluorescence studies also show that protein expression is increased greatly in mitotic MCF7 cells, and immunohistochemistry demonstrates its expression in human breast cancer cells. Analysis of mRNA levels in 25 different normal tissues by RT-PCR shows that this gene is expressed highly in normal prostate and salivary gland, very weakly in colon, pancreas, and intestine, and not at all in other tissues. RT-PCR studies on human cancer samples show that the RNA is expressed highly in many cancer cell lines and cancer specimens, including 26 of 33 human breast cancers, 3 of 3 prostate cancers, 3 of 3 colon cancers, and 3 of 3 pancreatic cancers. We name the protein CAPC, cytokeratin-associated protein in cancer.

Identification of proangiogenic genes and pathways by high-throughput functional genomics: TBK1 and the IRF3 pathway

A genome-wide phenotype screen was used to identify factors and pathways that induce proliferation of human umbilical vein endothelial cells (HUVEC). HUVEC proliferation is a recognized marker for factors that modulate vascularization. Screening "hits" included known proangiogenic factors, such as VEGF, FGF1, and FGF2 and additional factors for which a direct association with angiogenesis was not previously described. These include the kinase TBK1 as well as Toll-like receptor adaptor molecule and IFN regulatory factor 3. All three proteins belong to one signaling pathway that mediates induction of gene expression, including a mixture of secreted factors, which, in concert, mediate proliferative activity toward endothelial cells. TBK1 as the "trigger" of this pathway is induced under hypoxic conditions and expressed at significant levels in many solid tumors. This pattern of expression and the decreased expression of angiogenic factors in cultured cells upon RNA-interference-mediated ablation suggests that TBK1 is important for vascularization and subsequent tumor growth and a target for cancer therapy.

Discovery of the breast cancer gene BASE using a molecular approach to enrich for genes encoding membrane and secreted proteins

To identify unknown membrane proteins that could be used as targets for breast and prostate cancer immunotherapies and secreted proteins to be used as diagnostic markers, a cDNA library was generated from membrane-associated polyribosomal RNA derived from four breast cancer cell lines, one normal breast cell line, and a prostate cancer cell line. The membrane-associated polyribosomal cDNA library was subtracted with RNA from normal brain, liver, lung, kidney, and muscle. Of the 15,581 clones sequenced from the subtracted cDNA library, sequences from 10,506 clones map to known genes, but 5,075 sequences, representing 3,181 unique transcripts, are not associated with known genes. As one example, we experimentally investigated expression of a previously uncharacterized breast cancer gene that encodes a secreted protein designated BASE (breast cancer and salivary gland expression). BASE is expressed in many breast cancers but not in essential normal tissues including the five organs used for subtraction. Further analysis of this library should yield additional gene products of use in the diagnosis or treatment of breast or prostate cancer.

Characterization of overlapping XAGE-1 transcripts encoding a cancer testis antigen expressed in lung, breast, and other types of cancers

Cancer testis (CT) antigens have an expression pattern that is predominantly restricted to testis in normal tissues, yet they are expressed in many different histological types of cancers. One previously described member of the CT antigen family, XAGE-1, was shown to be expressed in Ewing's sarcomas and rhabdomyosarcomas. Here we show that XAGE-1 is also expressed in breast cancer, prostate cancer, and different types of lung cancers, including lung squamous cell carcinoma, adenocarcinoma, small cell lung carcinoma, and non-small cell lung carcinoma. In addition, XAGE-1 mRNA was present in ovarian cancer, melanoma, glioblastoma, T-cell lymphoma, chronic myelogenous leukemia, and histiocytic lymphoma cell lines. We also characterized the XAGE-1 transcript by primer extension analysis and found that transcription of the XAGE-1 gene is initiated from two distinct start sites, resulting in two overlapping transcripts, XAGE-1a and XAGE-1b. XAGE-1a contains two in-frame ATG translational start codons; whereas XAGE-1b initiates downstream of the first ATG start codon. Our results suggest that XAGE-1b is the dominant transcript, and that translation begins with the second ATG start codon, producing a 9 kDa protein. Because XAGE-1 is expressed in such a diverse range of cancers, it has potential to be used as a target for many cancer immunotherapies.

Quorum sensing in Vibrio fischeri: analysis of the LuxR DNA binding region by alanine-scanning mutagenesis

LuxR is the transcriptional activator for quorum-sensing control of luminescence in Vibrio fischeri. A series of alanine-scanning mutants spanning a predicted helix-turn-helix region in the DNA binding domain of LuxR was constructed, and the activity of each of the LuxR mutant proteins in recombinant Escherichia coli was investigated. The region covered by the mutagenesis spanned residues 190 to 224. About half of the alanine-scanning mutants showed activities similar to that of the wild-type LuxR: at least two were positive-control mutants, four appeared to be defective in DNA binding, and several others were characterized as DNA binding affinity mutants. This analysis, taken together with information about other bacterial transcription factors, provides insights into amino acid residues in LuxR that are involved in DNA binding and transcriptional activation.

Conversion of the Vibrio fischeri transcriptional activator, LuxR, to a repressor

The Vibrio fischeri luminescence (lux) operon is regulated by a quorum-sensing system that involves the transcriptional activator (LuxR) and an acyl-homoserine lactone signal. Transcriptional activation requires the presence of a 20-base inverted repeat termed the lux box at a position centered 42.5 bases upstream of the transcriptional start of the lux operon. LuxR has proven difficult to study in vitro. A truncated form of LuxR has been purified, and together with sigma(70) RNA polymerase it can activate transcription of the lux operon. Both the truncated LuxR and RNA polymerase are required for binding to lux regulatory DNA in vitro. We have constructed an artificial lacZ promoter with the lux box positioned between and partially overlapping the consensus -35 and -10 hexamers of an RNA polymerase binding site. LuxR functioned as an acyl-homoserine lactone-dependent repressor at this promoter in recombinant Escherichia coli. Furthermore, multiple lux boxes on an independent replicon reduced the repressor activity of LuxR. Thus, it appears that LuxR can bind to lux boxes independently of RNA polymerase binding to the promoter region. A variety of LuxR mutant proteins were studied, and with one exception there was a correlation between function as a repressor of the artificial promoter and activation of a native lux operon. The exception was the truncated protein that had been purified and studied in vitro. This protein functioned as an activator but not as a repressor in E. coli. The data indicate that the mutual dependence of purified, truncated LuxR and RNA polymerase on each other for binding to the lux promoter is a feature specific to the truncated LuxR and that full-length LuxR by itself can bind to lux box-containing DNA.

Quorum sensing in Vibrio fischeri: elements of the luxl promoter

Although cell density-dependent regulation of the luminescence genes in Vibrio fischeri is a model for quorum sensing in Gram-negative bacteria, relatively little is known about the promoter of the luminescence operon. The luminescence operon is activated by the LuxR protein, which requires a diffusible acylhomoserine lactone signal. The lux box, a 20 bp inverted repeat, is located in the luxl promoter region and is required for LuxR-dependent induction of the luminescence genes. Using primer extension, we mapped the LuxR-dependent transcriptional start site of the lux operon to 19 bp upstream of the luxl start codon. This indicates that the lux box is centred at -42.5 bp from the start of transcription. To gain evidence about the location of the -10 sequence, we placed a consensus -35 hexamer at different locations relative to the luxl transcriptional start site and measured constitutive levels of luminescence in recombinant Escherichia coli. The strongest constitutive promoter contained a TATAGT hexamer 17 bp from the -35 consensus sequence and 6 bp from the transcriptional start site. We propose that this is the -10 hexamer. Also in recombinant E. coli, both half-sites of the lux box were required for LuxR-dependent gene activation and for activation by an autoinducer-independent, monomeric LuxR deletion protein. LuxR-dependent activation of luminescence was eliminated when the lux box was centred at -47.5, -52.5 and -62.5 with respect to the luxl transcriptional start site. Our evidence, taken together with other information, points to a model in which a LuxR dimer overlaps the -35 region of the luxl promoter and functions as an ambidextrous activator with each LuxR subunit interacting with a different region of RNA polymerase.