Sunitinib in Patients With Breast Cancer With FGFR1 or FGFR2 Amplifications or Mutations: Results From the Targeted Agent and Profiling Utilization Registry Study

PURPOSE

The Targeted Agent and Profiling Utilization Registry Study is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results from cohorts of patients with metastatic breast cancer (BC) with FGFR1 and FGFR2 alterations treated with sunitinib are reported.

METHODS

Eligible patients had measurable disease, Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. Simon's two-stage design was used with a primary end point of disease control (DC), defined as objective response (OR) or stable disease of at least 16 weeks duration (SD16+) according to RECIST v1.1. Secondary end points included OR, progression-free survival, overall survival, duration of response, duration of stable disease, and safety.

RESULTS

Forty patients with BC with FGFR1 (N = 30; amplification only n = 26, mutation only n = 1, both n = 3) or FGFR2 (N = 10; amplification only n = 2, mutation only n = 6, both n = 2) alterations were enrolled. Three patients in the FGFR1 cohort were not evaluable for efficacy; all patients in the FGFR2 cohort were evaluable. For the FGFR1 cohort, two patients with partial response and four with SD16+ were observed for DC and OR rates of 27% (90% CI, 13 to 100) and 7% (95% CI, 1 to 24), respectively. The null hypothesis of 15% DC rate was not rejected (P = .169). No patients achieved DC in the FGFR2 cohort (P = 1.00). Thirteen of the 40 total patients across both cohorts had at least one grade 3-4 adverse event or serious adverse event at least possibly related to sunitinib.

CONCLUSION

Sunitinib did not meet prespecified criteria to declare a signal of antitumor activity in patients with BC with either FGFR1 or FGFR2 alterations. Other treatments and clinical trials should be considered for these patient populations.

The BET degrader ZBC260 suppresses stemness and tumorigenesis and promotes differentiation in triple-negative breast cancer by disrupting inflammatory signaling

BACKGROUND

Breast cancer stem cells (BCSCs) are resistant to standard therapies, facilitate tumor dissemination, and contribute to relapse and progression. Super-enhancers are regulators of stemness, and BET proteins, which are critical for super-enhancer function, are a potential therapeutic target. Here, we investigated the effects of BET proteins on the regulation of breast cancer stemness using the pan-BET degrader ZBC260.

METHODS

We evaluated the effect of ZBC260 on CSCs in TNBC cell lines. We assessed the effect of ZBC260 on cellular viability and tumor growth and measured its effects on cancer stemness. We used RNA sequencing and stemness index to determine the global transcriptomic changes in CSCs and bulk cells and further validated our findings by qPCR, western blot, and ELISA.

RESULTS

ZBC260 potently inhibited TNBC growth both in vitro and in vivo. ZBC260 reduced stemness as measured by cell surface marker expression, ALDH activity, tumorsphere number, and stemness index while increasing differentiated cells. GSEA analysis indicated preferential downregulation of stemness-associated and inflammatory genes by ZBC260 in ALDH+ CSCs.

CONCLUSIONS

The BET degrader ZBC260 is an efficient degrader of BET proteins that suppresses tumor progression and decreases CSCs through the downregulation of inflammatory genes and pathways. Our findings support the further development of BET degraders alone and in combination with other therapeutics as CSC targeting agents.

Identifying Barriers and Facilitators to Scalp Cooling Therapy Through a National Survey of the Awareness, Practice Patterns, and Attitudes of Oncologists

PURPOSE

Scalp cooling therapy (SCT) is the most effective method to reduce chemotherapy-induced alopecia (CIA), a highly distressing side effect of cancer treatment. Despite data supporting SCT efficacy and safety, SCT use in the United States is not widespread. Oncologists' interactions with scalp cooling were examined to identify facilitators and barriers to SCT implementation.

METHODS

A 33-question survey was distributed through the ASCO Research Survey Pool to a nationally representative, random sample of 600 oncology providers. Outcome measures included knowledge of SCT, frequency of initiating conversations about SCT with patients, degree of support, and barriers for SCT. Significance was defined as P < .001.

RESULTS

Of 155 (25.8%) responding providers, 62% of providers were in favor of SCT always or most of the time, but only 26% reported initiating discussions about SCT always or most of the time. Providers who treat breast cancer (P ≤ .0001), those who report being very familiar with SCT (P ≤ .0001), those who report having read SCT literature in the past 2 years (P ≤ .0001), and those who work at a facility with machine SCT (P ≤ .0001) were significantly more likely to initiate conversations with patients about SCT. Financial concerns (58%) were the primary reason for not recommending SCT use; efficacy (31%), staff or facility (24%), and safety (15%) concerns were also noted. Although safety concerns have decreased markedly over time, 14% of providers report patients who continue to express these concerns and 17% of providers see safety issues as barriers to supporting SCT.

CONCLUSION

Our findings suggest that oncology provider familiarity and experience with SCT lead to increased support for scalp cooling, which may ultimately result in greater availability and utilization of SCT when indicated.

Abstract CT173: Sunitinib (S) in patients (pts) with metastatic breast cancer (mBC) with FGFR1 mutations or amplifications: Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study

Background: TAPUR is a phase II basket study evaluating anti-tumor activity of commercially available targeted agents in pts with advanced cancers with genomic alterations. S is an oral multi-kinase inhibitor that inhibits Fibroblast Growth Factor Receptor family members 1-4 (FGFR1-4) in biochemical and cellular assays and is FDA approved in several tumor types. Results in a cohort of mBC pts with FGFR1 mutations (mut) or amplifications (amp) treated with S are reported.

Methods: Eligible pts had mBC, no standard treatment (tx) options, measurable disease, ECOG Performance Status (PS) 0-2, and adequate organ function. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Pts received S 50 mg orally daily for four weeks followed by two weeks off, until tumor progression. Simon 2-stage design tested the null disease control (DC) - defined as partial (PR), complete response (CR) or stable disease at 16+ weeks (SD 16+) - rate of 15% vs. 35% (power = 0.85; α = 0.10). If ≥2 of 10 pts in stage 1 have DC, 18 more pts are enrolled. If ≥7 of 28 pts have DC, the null DC rate is rejected. Secondary endpoints are progression-free survival (PFS), overall survival (OS) and safety.

Results: Thirty pts with mBC with FGFR1 mut (1 pt), amp (28 pts), or both (1 pt) were enrolled from Oct 2016 to June 2019. 3 were not evaluable and excluded from efficacy analyses. Demographics and outcomes are summarized in Table 1. Two partial responses (PR) and 5 SD16+ (FGFR1 amp only) were observed for DC and OR rates of 29% (95% CI: 13%, 42%) and 7% (95% CI: 1%, 24%), respectively, and the null DC rate of 15% was rejected (p=0.09). S related grade 3-5 TAEs (Table 1) were consistent with the product label for S except encephalopathy.

Conclusions: Monotherapy S showed modest anti-tumor activity and clinically significant TAEs in heavily pre-treated pts with mBC with FGFR1 amplification.

Table 1.Demographics, Efficacy (N=27) and Toxicity Outcomes (N=30)Median age, yrs (range)61 (28, 81)Female, %97ECOG PS, %047137217Prior systemic regimens, %1-210≥390Hormone Receptor (HR) & HER2 Status, %HR (+) HER2 (-)77HR (-) HER2(-)13HR (+) HER2 (+)7Not reported3DC rate, % (OR or SD16+) (95% CI)29 (13, 42)OR rate, % (95% CI)7 (1, 24)Median PFS, wks (95% CI)8.7 (8.1, 15.7)Median OS, wks (95% CI)33.9 (23.0, 49.0)Number of Pts with Treatment-related AEs/SAEs (TAEs, maximum grade reported)Grade 211Grade 329Grade 4321Skin infection (SAE)2Cytopenia, encephalopathy (SAE), febrile neutropenia (SAE), increased alkaline phosphatase, Palmar-plantar erythrodysesthesia syndrome, vomiting3Cytopenia, hypertension

Citation Format: Carmen Calfa, Michael Rothe, Pam K. Mangat, Elizabeth Garrett-Mayer, Eugene Ahn, Keerthi Gogineni, Nitin Rohatgi, Monika L. Burness, Anu Gaba, Omid Hamid, Tareq Albaghdadi, Alison Conlin, Philip Gold, Jordi Rodon, Ramya Thota, Richard L. Schilsky. Sunitinib (S) in patients (pts) with metastatic breast cancer (mBC) with FGFR1 mutations or amplifications: Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT173.

Abstract P2-05-05: RAD51 inhibition using CYT-0851, shows anti-cancer activity in cellular models of breast cancer and acts synergistically with PARP inhibitors

Genomic instability is recognized as a driver of tumorigenesis and cancer progression. Loss of tumor suppressors or activation of oncogenes can induce DNA damage stress, promoting genomic instability and creating dependencies upon key DNA repair pathways. The clinical success of PARP inhibitors has highlighted the potential of targeting these dependencies therapeutically to induce synthetic lethality. We have developed novel RAD51 inhibitors to selectively target cancers that have elevated levels of DNA damage and/or reduced levels of DNA repair. RAD51 is a critical component of the homologous recombination (HR) pathway, forming nucleoprotein filaments at sites of DNA damage or replication fork stalls. RAD51 mediates homologous DNA strand exchange to promote recombinational repair of breaks and damaged replication forks. We have previously shown anti-cancer activity of RAD51 inhibitors in preclinical xenograft mouse models of lymphomas that have elevated rates of DNA mutations due to aberrant expression of Activation Induced Cytidine Deaminase (AID). Breast cancer, due to high rates of genomic instability, may potentially be treated in this fashion. Here we present the characterization of our RAD51 inhibitors in breast cancer. In a murine cell line model of metastatic breast cancer, 4T1, treatment with CYT-0851 resulted in a reduction in homologous recombination activity in a sister chromatid exchange (SCE) assay at a similar rate observed in a human derived cell line (HEK293T) suggesting conservation of mechanism in human and murine models. In the same cell line, treatment with CYT-0851 and a DNA damaging agent, carboplatin, resulted in cellular toxicity above what was observed with CYT-0851, indicating that RAD51 inhibition coupled with genomic instability is cytotoxic in this breast cancer model. PARP inhibitors have been shown to induce genomic instability as measured by an increase in HR activity in SCE assays. We therefore hypothesized that our RAD51 inhibitor could act as a sensitizer to PARP inhibitors. Combinatorial treatment of 4T1 cells with CYT-0851 and olaparib reduced homologous recombination activity in the SCE assay. Additionally, combination therapy led to increased accumulation of gH2AX foci after ionizing radiation, and increased tail moment on neutral Comet assay. Chou-Talalay synergy assay demonstrated synergistic activity between olaparib and CYT-0851 in 4T1. To determine potential drug synergy in human models, a matrix study was performed with CYT-0851 and olaparib in three cell lines of triple negative breast cancer (HCC1937, HCC1143, and BT20). Concentration-dependent synergy was observed in all cell lines tested. These data suggest that CYT-0851 may be active as a mono therapy and a combinatorial therapy with PARP inhibitors in breast cancer. Overall, we conclude that the synergy observed in vitro indicates significant potential for RAD51 inhibition in future cancer treatment strategies and warrants future exploration in vivo.

Citation Format: Joey L Guy, Tyler Maclay, Melinda Day, Monika L Burness, Kevin Mills. RAD51 inhibition using CYT-0851, shows anti-cancer activity in cellular models of breast cancer and acts synergistically with PARP inhibitors [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-05-05.

Genetic variation in EPHA contributes to sensitivity to paclitaxel-induced peripheral neuropathy

AIMS

Chemotherapy-induced peripheral neuropathy (PN) is a treatment limiting toxicity of paclitaxel. We evaluated if EPHA genetic variation (EPHA4, EPHA5, EPHA6, and EPHA8) is associated with PN sensitivity by accounting for variability in systemic paclitaxel exposure (time above threshold).

METHODS

Germline DNA from 60 patients with breast cancer was sequenced. PN was measured using the 8-item sensory subscale (CIPN8) of the patient-reported CIPN20. Associations for 3 genetic models were tested by incorporating genetics into previously published PN prediction models integrating measured paclitaxel exposure and cumulative treatment. Significant associations were then tested for association with PN-related treatment disruption.

RESULTS

EPHA5 rs7349683 (minor allele frequency = 0.32) was associated with increased PN sensitivity (β-coefficient = 0.39, 95% confidence interval 0.11-0.67, p = 0.007). Setting a maximum tolerable threshold of CIPN8 = 30, optimal paclitaxel exposure target is shorter for rs7349683 homozygous (11.6 h) than heterozygous (12.6 h) or wild-type (13.6 h) patients. Total number of missense variants (median = 0, range 0-2) was associated with decreased PN sensitivity (β-coefficient: -0.42, 95% confidence interval -0.72 to -0.12, P = .006). No association with treatment disruption was detected for the total number of missense variants or rs7349683.

CONCLUSION

Isolating toxicity sensitivity by accounting for exposure is a novel approach, and rs7349683 represents a promising marker for PN sensitivity that may be used to individualize paclitaxel treatment.

Young Women with Breast Cancer: Fertility Preservation Options and Management of Pregnancy-Associated Breast Cancer

BACKGROUND

Breast cancer is the most common malignancy diagnosed in women of childbearing age. A breast cancer diagnosis in this young patient population can be uniquely complex to navigate when considering the potential impact of fertility loss associated with specific gonadotoxic therapies. Another unique challenge for young breast cancer patients is pregnancy-associated breast cancer (PABC), which occurs in approximately 1 of every 3000 pregnancies. Pregnancy adds a layer of complexity to breast cancer treatment planning as many therapies can affect the developing fetus. These two clinical challenges require nuanced multidisciplinary approaches to facilitate optimal treatment outcomes. We sought to review and summarize the management strategy options for both fertility preservation and PABC.

METHODS

A guideline and literature review was performed for fertility preservation, young patients with breast cancer, and pregnancy-associated breast cancer.

RESULTS

Fertility preservation options, both established and experimental, are detailed. Suggested clinical practice guidelines for PABC are also presented, which delineate breast cancer treatment recommendations based on pregnancy trimester.

CONCLUSION

A multidisciplinary approach to patient care, including oncologists and early referral to reproductive specialists, can provide young breast cancer patients with options for fertility preservation. Under the guidance of a multidisciplinary treatment team, PABC can also be diagnosed and treated to permit the best possible outcomes for the mother and the developing fetus.

Patients carrying CYP2C8*3 have shorter systemic paclitaxel exposure

AIM

First, evaluate if patients carrying putatively diminished activity CYP2C8 genotype have longer paclitaxel exposure (e.g., time above threshold concentration of 0.05 μM [T_{c >0.05}]). Second, screen additional pharmacogenes for associations with T_{c >0.05}. Methods: Pharmacogene panel genotypes were translated into genetic phenotypes for associations with T_{c >0.05} (n = 58).

RESULTS

Patients with predicted low-activity CYP2C8 had shorter T_{c >0.05} after adjustment for age, body surface area and race (9.65 vs 11.03 hrs, β = 5.47, p = 0.02). This association was attributed to CYP2C8*3 (p = 0.006), not CYP2C8*4 (p = 0.58). Patients with predicted low-activity SLCO1B1 had longer T_{c >0.05} (12.12 vs 10.15 hrs, β = 0.85, p = 0.012).

CONCLUSION

Contrary to previous publications, CYP2C8*3 may confer increased paclitaxel metabolic activity. SLCO1B1 and CYP2C8 genotype may explain some paclitaxel pharmacokinetic variability.

Characterizing Circulating Tumor Cells Isolated from Metastatic Breast Cancer Patients Using Graphene Oxide Based Microfluidic Assay

The enumeration of circulating tumor cells (CTCs) has shown prognostic importance in patients with breast cancer. However, CTCs are highly heterogeneous with diverse functional properties, which may also be clinically relevant. To provide a comprehensive landscape of the patient's disease, further CTC analysis is required. Here, a highly sensitive and reproducible graphene oxide based CTC assay is utilized to isolate and characterize CTCs from 47 metastatic breast cancer patients. The CTCs are captured with high purity, requiring only a few milliliters of blood and enabling efficient enumeration and subsequent analysis at both the protein and the transcription level. The results show that patient clinical outcomes correlate with the associated CTC profile and clearly demonstrate the potential use of the assay in the clinical setting. Collectively, these findings suggest that beyond simple enumeration, CTC characterization may provide further information that improves the diagnosis of the patients' disease status for proper treatment decisions. Moreover, this thorough validation study will facilitate the translation of the CTC assay into future clinical applications to broaden the utility of liquid biopsy.

Abstract P2-09-26: Frequency and mechanisms of elevated somatic mutation burden in metastatic breast cancer and response to immune checkpoint blockade

Background: Immune checkpoint blockade (ICB) is effective in the treatment of various malignancies. Thus far, however, results in breast cancer have been mixed. Elevated tumor mutational load, and subsequent increased likelihood of forming immunogenic neoantigens, has been correlated with response to ICB. Mutational load observed in breast cancers varies widely. However, most studies have assessed mutational load using primary tumors. Few studies have explored the frequency of high mutational load, molecular mechanisms accounting for this phenomenon, and its potential impact on response to ICB in metastatic breast cancer (MBC).

Methods: From 2011-2016, 124 patients (pts) with MBC of varying subtypes underwent research biopsy of their metastatic disease for whole genome, exome and transcriptome sequencing of tumor and matched normal sample through the Michigan Oncology Sequencing Center (Mi-OncoSeq). Those pts with elevated somatic mutation load were defined as having greater than 10 mutations per megabase of targeted sequencing and mutational signatures accounting for high mutation load were noted. Pts treated subsequently with ICB were followed to assess response.

Results: Twelve MBC pts had high mutation load (10% of cohort). Eight pts had estrogen receptor (ER) positive MBC and 4 pts had metastatic triple negative breast cancer (TNBC). In 5 cases, a clear mutational signature accounting for high mutation load was evident. Two TNBC cases harbored an APOBEC mutational signature in addition to 1 TNBC and 2 ER positive tumors displaying a microsatellite instability signature (MSI-H). Among the tumors with MSI-H signature, 1 case was associated with a pathogenic germline alteration in MLH1. Two pts were subsequently treated with ICB on a clinical trial. One pt came off study after 3 months due to progressive brain metastases and another had partial response to therapy lasting 7 months.

Conclusions: Elevated somatic mutation burden in MBC is observed in approximately 10% of pts, and is detected in both ER positive and TNBC. Since high mutation burden has been associated with increased likelihood of response to ICB, identification of this genomic feature could have important therapeutic implications for MBC pts.

Citation Format: Cobain EF, Robinson DR, Wu Y-M, Lonigro R, Vats P, Rabban E, Kumar-Sinha C, Schott AF, Smerage JB, Morikawa A, Burness ML, Van Poznak CH, Griggs J, Wicha M, Hayes DF, Chinnaiyan AM. Frequency and mechanisms of elevated somatic mutation burden in metastatic breast cancer and response to immune checkpoint blockade [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 P2-09-26.

Dormant breast cancer micrometastases reside in specific bone marrow niches that regulate their transit to and from bone

Breast cancer metastatic relapse can occur years after therapy, indicating that disseminated breast cancer cells (BCCs) have a prolonged dormant phase before becoming proliferative. A major site of disease dissemination and relapse is bone, although the critical signals that allow circulating BCCs to identify bone microvasculature, enter tissue, and tether to the microenvironment are poorly understood. Using real-time in vivo microscopy of bone marrow (BM) in a breast cancer xenograft model, we show that dormant and proliferating BCCs occupy distinct areas, with dormant BCCs predominantly found in E-selectin- and stromal cell-derived factor 1 (SDF-1)-rich perisinusoidal vascular regions. We use highly specific inhibitors of E-selectin and C-X-C chemokine receptor type 4 (CXCR4) (SDF-1 receptor) to demonstrate that E-selectin and SDF-1 orchestrate opposing roles in BCC trafficking. Whereas E-selectin interactions are critical for allowing BCC entry into the BM, the SDF-1/CXCR4 interaction anchors BCCs to the microenvironment, and its inhibition induces mobilization of dormant micrometastases into circulation. Homing studies with primary BCCs also demonstrate that E-selectin regulates their entry into bone through the sinusoidal niche, and immunohistochemical staining of patient BMs shows dormant micrometastatic disease adjacent to SDF-1(+) vasculature. These findings shed light on how BCCs traffic within the host, and suggest that simultaneous blockade of CXCR4 and E-selectin in patients could molecularly excise dormant micrometastases from the protective BM environment, preventing their emergence as relapsed disease.

Therapeutic Implications of Cellular Heterogeneity and Plasticity in Breast Cancer

Cellular heterogeneity represents one of the greatest challenges in cancer therapeutics. In many malignancies, this heterogeneity is generated during tumor evolution through a combination of genetic alterations and epigenetic events that recapitulate normal developmental processes including stem cell self-renewal and differentiation. Many, if not most, tumors display similar hierarchal organization, at the apex of which are "stem-like cells" that drive tumor growth, mediate metastasis, and contribute to treatment resistance. Using breast cancer as a model, we discuss how an improved understanding of tumor cellular heterogeneity and plasticity may lead to development of more effective therapeutic strategies.

Tunable Thermal-Sensitive Polymer-Graphene Oxide Composite for Efficient Capture and Release of Viable Circulating Tumor Cells

A highly sensitive microfluidic system to capture circulating tumor cells from whole blood of cancer patients is presented. The device incorporates graphene oxide into a thermoresponsive polymer film to serve as the first step of an antibody functionalization chemistry. By decreasing the temperature, captured cells may be released for subsequent analysis.

Abstract 4454: Targeting the gp130 receptor in preclinical models of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) with poor clinical outcomes and limited therapeutic options. To date, efforts to implement targetted therapy in TNBC have had limited success. Cumulative evidence suggest that cancer stem cells (CSCs) drive resistance to therapy, tumor recurrence, and may play a determinant role in the aggressive biology of TNBC. Recent studies indicate that CSCs are in reciprocal interaction with tumor microenvironment through cytokine-mediated signaling pathways. IL-6 is emerging as an important mediator of tumor growth and CSC survival. IL-6 is the most studied ligand of the gp130 receptor, which is a potent activator of the JAK/STAT3 signaling pathway important in survival and proliferation. The gp130 receptor is emerging as a promising target for cancer therapy. SC144 is a novel first-in-class gp130 inhibitor that has shown preclinical efficacy in ovarian cancer models. This study explores the effect of gp130 inhibition with SC144 on TNBC preclinical models.

Methods: SC144 was provided by Dr. Neamati's laboratory currently at the University of Michigan. We conducted in vitro studies using well-characterized human BC cell lines with a triple-negative phenotype. The effect of the novel compound SC144 on TNBC cell lines was evaluated using MTT assays for growth inhibition, ALDEFLUOR assay for identification of CSCs, ELISA tests for cytokine levels, and qRT-PCR for gene expression analysis.

Results: SC144 inhibits cell growth in the TNBC cell lines SUM159, SUM149, MDAMB231, and HCC38 with IC50 values in a submicromolar range (0.87+0.17 μmol/L, 0.9+0.1 μmol/L, 0.5 μmol/L, 0.4 μmol/L, respectively). In an in vitro culture system of the TNBC cell line SUM159, docetaxel treatment induces a three-fold increase in IL-6 levels by ELISA and increases the CSC population measured by ALDEFLUOR. Pretreatment of SUM159 cells with SC144 significantly sensitized cells to docetaxel. Treatment of SUM159 cells with SC144 in addition to docetaxel significantly reduced the ALDH+ population measured by ALDEFLUOR compared to docetaxel alone (7.79+1% vs 22.23+5%). Investigating the potential effect of SC144 on the CSC population, we found a higher expression level of the IL-6 receptor in ALDH+ cells compared to ALDH- and the bulk population. Furthermore, in SUM159 cells treated with SC144 vs. control for 24 hours we found a significant decrease on expression of genes with documented relevance in CSC maintenance including CD44 (0.08 vs. 0.13), ALDH1a1 (0.001 vs. 0.006), STAT1 (0.004 vs. 0.024) and STAT3 (0.003 vs. 0.014). The in vivo study to test the efficacy of SC144 in a SUM159 xenograft model is undergoing.

Conclusions: SC144, a novel gp130 inhibitor, has antitumor activity in human BC cell lines with the triple-negative phenotype. SC144 sensitizes cells to docetaxel therapy, and demonstrates an inhibitory effect on the CSC subpopulation. These findings identify a potential therapeutic target for TNBC.

Citation Format: Leonel F. Hernandez-Aya, Yajing Liu, Kelsey Kerr, Shuzo Tamura, Nouri Neamati, Max S. Wicha, Monika L. Burness. Targeting the gp130 receptor in preclinical models of triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4454. doi:10.1158/1538-7445.AM2015-4454

Abstract 376: Capture and release of circulating tumor cells by temperature-sensitive graphene oxide-polymer composite

Introduction and Objective: Recently, various microfluidics-based circulating tumor cells (CTC) isolation technologies have been developed to isolate, enumerate, and characterize CTCs, but there are few studies reporting CTC release after selective capture. Existing devices face impediments to the easy release of captured cells due to the conjugation of antibodies to permanent structures within the devices. Here we present a tunable microfluidic polymer graphene oxide (GO) Chip based on a temperature-sensitive graphene oxide-polymer composite for selective capture and efficient subsequent release of CTCs.

Methods: A blend film of GO sheets and thermo-responsive polymers serves as a platform enabling cell capture and release in our microfluidic devices. The polymers with a tunable lower critical solution temperature (LCST) allow for stimulated release of the captured cells when the device temperature is below the LCST. The GO sheets serve as a carrier for phosophlipid-PEG-amine, which is used for the immobilization of an antibody against the epithelial-cell-adhesion-molecule (EpCAM). To investigate the capture efficiency, MCF-7 cells labeled with cell tracker dye were spiked into 1 mL of whole blood and flowed through the microfluidic device. After thoroughly washing the device with PBS at 25 °C to remove any non-specifically bound cells, we dissolved the thermo-responsive composite with 1 mL of PBS at 5 °C in a cold room and collected released cells from the device outlet. The released cells were cytospun and stained to identify CTCs as cytokeratin positive, DAPI positive, and CD45 negative cells. We also tested peripheral blood samples obtained from patients with metastatic breast cancer in a similar manner.

Results: The graphene oxide-polymer based CTC-chip showed a capture efficiency of 95.21% at 95.21% and a release efficiency of 92.45% for MCF-7 breast cancer cells. This new GO Chip was also able to isolate viable CTCs from blood samples of metastatic breast cancer patients for further molecular characterizations.

Conclusion: We present a sensitive and tunable microfluidic chip based on a GO-polymer composite to capture, release, identify, and characterize extremely rare CTCs. The CTCs released from the chip are viable, suggesting that this polymer based GO Chip offers great potential for clinical applications due to its high-affinity cell capture and the ability to enable various downstream analyses of captured CTCs.

Citation Format: Hyeun Joong Yoon, Apoorv Shanker, Yang Wang, Molly Kozminsky, Shamileh Fouladdel, Monika L. Burness, Ebrahim Azizi, Max S. Wicha, Jinsang Kim, Sunitha Nagrath. Capture and release of circulating tumor cells by temperature-sensitive graphene oxide-polymer composite. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 376. doi:10.1158/1538-7445.AM2015-376

Abstract 4726: Gene expression signatures of isolated circulating tumor cells from metastatic breast cancer patients reveal presence of breast cancer stem cells with EMT or MET phenotypes

Breast cancer stem cells are responsible for tumor recurrence, metastasis and drug resistance. One of the important steps in metastasis is entry of tumor cells into the blood circulation. These circulating tumor cells (CTCs) may serve as markers of cancer progression and as a “liquid biopsy” to provide information on tumor biology at single cell resolution. Current methods of CTC capture are not fully inclusive to isolate all phenotypic variations of cancer stem cells (CSCs) among the CTCs. Using newly developed microfluidic methods to isolate CTCs from blood samples of metastatic breast cancer patients, we assessed gene expression profiles in these cells. The gene expression signatures of isolated CTCs were determined using a highly sensitive microfluidic-based 96-plex RT-qPCR method. Analyzed multiplex RT-qPCR data revealed distinct gene expression patterns among CTCs isolated from different patients. Cancer stem cell markers such as ALDH1a1, ALDH1a2 and ALDH1a3 as well as CD44 and CD24 genes were differentially expressed in isolated CTCs. In addition, markers of the epithelial to mesenchymal (EMT) and mesenchymal to epithelial (MET) phenotypes such as Vimentin, EpCAM, HER2, CDH1, CDH2, TGFb1 and cytokeratins were also expressed variably in the CTC samples. Furthermore, MMP9, TIMP1, CD90, CD14, SPARC, BRAF, KRAS, PI3K and ERCC1 genes which play a role in cancer initiation, promotion, metastasis and drug resistance were also differentially expressed in the isolated CTCs. Overall, these studies further our understanding into the heterogeneity of CTCs and CSCs as well as providing a potential tool for real-time monitoring of cancer patients on clinical trials.

Citation Format: Shamileh Fouladdel, Hyeun Joong Yoon, Eric Lin, Tae Hyun Kim, Yadwinder S. Deol, Tahra K. Luther, Shawn G. Clouthier, Hui Jiang, Monika L. Burness, Sunitha Nagrath, Ebrahim Azizi, Max S. Wicha. Gene expression signatures of isolated circulating tumor cells from metastatic breast cancer patients reveal presence of breast cancer stem cells with EMT or MET phenotypes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4726. doi:10.1158/1538-7445.AM2015-4726

Abstract 1593: Label-free high throughput microfluidic device for the isolation of circulating tumor cells from breast cancer patients

Introduction and Objective: A necessary step in distant metastasis is the hematogenous dissemination of cancer cells from the primary tumor site to remote sites. The presence of circulating tumor cells (CTCs) in the peripheral blood represents a strong and independent prognostic factor for decreased disease-free and overall survival in many solid malignancies. Immune-affinity based capture is the most commonly used method for the isolation of CTCs which utilizes antibodies to capture tumor cells expressing specific proteins. However, immune-affinity based approaches offer low throughput (∼1mL/hr) and considerable cell loss (∼20-40%) resulting from heterogeneous expression of biomarkers on CTCs. Various label-free approaches utilizing physical properties of CTCs have been developed to overcome the limitations of immune-affinity based isolation techniques, including micro-filters, microscale laminar vortices, inertial migration of particles, and integrated systems. Here we present an inertial microfluidic-based separation technique for high throughput and label-free isolation of CTCs that yields the highest throughput with high CTC recovery and high blood cell removal among all the label-free technologies.

Methods: The PDMS-made microfluidic device has 637 mm in length with 56 corners, 500 μm in width, and 100 μm in height. The separation is driven by two main forces: (i) inertial force that focuses the cells into streamlines, and (ii) drag force from Dean flow that migrates the focused cells to various positions based on size. The device was optimized with MCF-7 and Panc-1 cell lines spiked into PBS buffer and also diluted blood. It was then tested on 10 mL blood samples from patients with metastatic breast cancer. The separated cells were cytospun and stained to identify CTCs as cytokeratin positive, DAPI positive, CD45 negative cells.

Results: Samples were processed through the inertial microfluidic device that enriches CTCs in the second outlet based on size difference between CTCs and blood cells. The device was optimized to operate at an extremely high throughput of 2500 μL/min with high recovery (92% for both spiked samples of MCF-7 and PANC-1 cell lines) and high white blood cells (WBCs) removal (91%). To determine the efficiency of capture of rare cell populations, healthy donor blood samples were spiked with MCF-7/GFP at 100 cells and 95% recovery was obtained. In patient samples, we identified CTCs in 24 of 27 (89%) breast patients with metastatic disease (4.3±4.8 CTCs/mL) with low WBCs contamination (465±473 WBCs/mL).

Conclusion: The study of CTCs could have a direct impact upon patient care by presenting a novel CTC isolation method. This technology may be applicable to early detection, and also for monitoring response to treatment. Our approach is superior to current strategies because it is independent of cell surface markers, which may be varied in tumor cells, and may exclude cancer stem cells.

Citation Format: Eric Lin, Lianette Rivera, Hyeun Joong Yoon, Shamileh Fouladdel, Jacob Wieger, Stephanie Guthrie, Yadwinder S. Deol, Shawn G. Clouthier, Tahra K. Luther, Diane M. Simeone, Monika L. Burness, Ebrahim Azizi, Max S. Wicha, Sunitha Nagrath. Label-free high throughput microfluidic device for the isolation of circulating tumor cells from breast cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1593. doi:10.1158/1538-7445.AM2015-1593

Abstract 4828: Circulating tumor cells (CTCs) isolated from patients with metastatic breast cancer utilizing a sensitive microfluidic graphene oxide (GO) nanosheet device express markers of cancer stem cells

Breast cancers are driven by a subset of cells that display stem cell properties. These “cancer stem cells” (CSCs) mediate metastasis and contribute to treatment resistance. Many current CTC isolation technologies are limited in their sensitivity and are particularly inefficient at capturing cells which display an epithelial mesenchymal transition (EMT) phenotype which has been associated with CSCs. We have developed a sensitive microfluidic device using functionalized graphene oxide (GO) nanosheets to identify and isolate CTCs from patients with metastatic breast cancer. Unlike other CTC capture devices with microposts, the effective functionalized surface created by GO allows the device to be two-dimensional. The GO nanosheets were adsorbed onto the patterned gold surface and then chemically functionalized. Blood samples were collected into EDTA and AdnaGen tubes from patients with metastatic breast cancer and analyzed within 24 hours of blood sampling. Isolated CTCs were studied for expression of genes using a multiplex TaqMan-based qRT-PCR method. CTC preparations were checked for white blood cells (WBCs) contamination by examining CD45 expression and verifying that there was no or extremely low levels of CD45 expression in all of the processed samples. The majority of isolated CTCs showed mRNA expression of EMT markers including TGFβ and Vimentin at different levels among tested samples. In addition, markers of breast CSCs including CD44+/CD24- and ALDH1+ were observed in CTCs isolated from patients across the molecular subtypes of breast cancer. Interestingly, HER2+ CTCs were isolated from patients with HER2/neu- primary tumors. This is consistent with recent work from our group that demonstrated selective expression of HER2 in the CSC-like populations of luminal breast cancers occur independent of HER2 gene amplification. These studies demonstrate the feasibility of utilizing GO nanosheet microfluidic devices to isolate and molecularly characterize CTCs from metastatic breast cancer patients. Such liquid biopsies may be of particular value for following CSC populations for patients on therapeutic clinical trials.

Citation Format: Shamileh Fouladdel, Hyeun Joong Yoon, Tae Hyun Kim, An Shi, Tahra Luther, Jill Hayden, Shawn G. Clouthier, Yadwinder S. Deol, Monika L. Burness, Daniel F. Hayes, Sunitha Nagrath, Ebrahim Azizi, Max S. Wicha. Circulating tumor cells (CTCs) isolated from patients with metastatic breast cancer utilizing a sensitive microfluidic graphene oxide (GO) nanosheet device express markers of cancer stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4828. doi:10.1158/1538-7445.AM2014-4828

Interferon gamma-inducible protein 10 selectively inhibits proliferation and induces apoptosis in endothelial cells

BACKGROUND

Interferon gamma-inducible protein 10 (IP-10) has antitumor effects in various murine models. The IP-10 receptor has two distinct splice variants, CXCR3A and CXCR3B, that have paradoxical effects after ligand-receptor interaction.

METHODS

To characterize the putative antiangiogenic effects of IP-10, we measured proliferation rates and apoptosis in human umbilical vein endothelial cells (HUVECs), fibroblasts, and A375 melanoma or WIDR adenocarcinoma cell lines after exposure to the recombinant protein. CXCR3A (activating) and CXCR3B (inhibitory/proapoptotic) messenger RNA (mRNA) expression levels in fibroblasts, 2 human tumor cell lines, T lymphocytes, and HUVECs of varying cell densities were characterized.

RESULTS

IP-10 resulted in dose-dependent and selective inhibition of proliferation and countered the proliferative effects of vascular endothelial growth factor in HUVECs but did not affect fibroblasts or 2 human tumor cell lines. In addition, IP-10 resulted in potent and selective induction of apoptosis in HUVECS but had no effect on fibroblasts or A375 melanoma. Confluent HUVECs had a predominance of mRNA for the CXCR3B splice variant by reverse transcriptase-polymerase chain reaction, and the ratio of CXCR3B to CXCR3A mRNA was >40 in HUVECs, compared with </=10 in the other cell types. Moreover, CXCR3B mRNA levels were significantly higher in proliferating compared with confluent HUVECs. In vivo, systemic IP-10 administration resulted in slower A375 xenograft growth rates compared with control-treated animals, and immunohistochemical staining showed decreased microvessel density in xenografts of IP-10-treated mice.

CONCLUSIONS

IP-10 has antiangiogenic properties and selective effects on endothelial tissue that may be secondary to higher levels of the CXCR3B inhibitory/proapoptotic receptor in that cell type, particularly in its actively proliferating state.