POS0864 ASSESSMENT OF SYSTEMIC SCLEROSIS RELATED MYOCARDIAL FIBROSIS BY 68Ga-FAPI-04 PET/CT

Background

Myocardial fibrosis is a poor prognostic factor and a relevant cause of SSc-related mortality. Current non-invasive screening methods for myocardial fibrosis (MF) include echocardiography, electrocardiography and serum Nt-pro-BNP, which are not specific for MF and not sensitive for early changes. Cardiac MRI predominately visualizes extracellular space changes as consequence of long-standing fibroblast activation. Direct visualization of the remodeling fibrotic remodeling process has not been feasible so far.

Objectives

Here, we use a tracer labeled probe directed against Fibroblast-Activation-Protein (FAP) to visualize activated fibroblasts in the myocardium of SSc patients and healthy individuals to test the hypothesis that FAPI-based PET imaging might enable the assessment of disease activity in SSc-related MF.

Methods

In this exploratory trial, 7 patients with SSc-related myocardial fibrosis (MF) confirmed by cardic MRI and 8 SSc patients without myocardial involvement were enrolled. All participants underwent 68Ga-FAPI-04 PET/CT imaging and cardiac MRI as well as echocardiography, electrocardiogram, and serum NT-pro-BNP. Patients were followed for at least 6 months including a follow-up cardiac MRI. Regional mapping of 68Ga-FAPI-04-uptake, late gadolinium enhancement (LGE) and T1-relaxation times were performed according to the American Heart Association 17 regions model. Myocardial tissue was analysed by immunofluorescence- (aSMA and FAP) and Sirius-Red staining.

Results

Myocardial FAPI-04-accumulation was significantly increased in SSc patients with myocardial fibrosis as defined by LGE in MRI compared to SSc patients without LGE. Consistent with the previously reported widespread remodeling in SSc-associated myocardial disease, the distribution of FAPI uptake was observed across multiple areas and did not correspond to the supply areas of the coronary arteries. Histological analyses of myocardial tissue biopsied from a LGE and 68Ga-FAPI-04-positive region revealed the accumulation of FAP+; SMA+ myofibroblasts in regions of pronounced collagen deposition. Slightly increased 68Ga-FAPI-04 -uptake values were observed in SSc patients without LGE, but with cardiovascular risk factors.

Comparing 68Ga-FAPI-04-uptake with cardiac MRI based mapping techniques, we observed a partial overlap for certain regions and differences in others. These observations suggest, that 68Ga-FAPI-PET/CT and cMRI could visualize different aspects of the disease process.

To confirm that 68Ga-FAPI-04-uptake assesses current molecular fibroblast activity rather than accumulating disease damage, we analyzed associations of 68Ga-FAPI-04-uptake with changes of clinical parameters of SSc-MF on follow-up: Here we observed different dynamics of change of 68Ga-FAPI-04-uptake and cardiac MRI-based, e.g. in response to start of immunosuppressive therapy.

Conclusion

Our study presents first in human evidence on a limited number of patients that FAPI-04-uptake correlates with fibrotic activity in SSc-associated myocardial fibrosis and that 68Ga-FAPI-04-PET/CT may thus improve risk stratification in this population.

Disclosure of Interests

None declared

Abstract P1-17-05: Benefit of endocrine therapy for metastatic breast cancer after loss of hormone receptor expression in patients with HR+/HER2- primary tumors

Background. Loss of estrogen receptor (ER) and/or progesterone receptor (PR) expression between primary breast tumors and metastases occurs in one-fourth of patients. Loss of hormone receptor (HR) expression is associated with inferior clinical outcomes however optimal treatment strategies in this setting have not been defined. Methods. Patients with HR+/HER2- primary breast tumors and subsequent HR-/HER2- metastatic biopsies, as determined by immunohistochemical staining, were identified using the University of North Carolina Metastatic Breast Cancer Clinical Database which includes patients diagnosed with metastatic breast cancer from 2001-2019. Patients with second primary breast cancers were excluded. Clinical features were assessed using chi-square testing. Survival was analyzed using univariate and multivariate Cox proportional hazards modeling. Results. 1,240 patients had known primary breast and metastatic biopsy receptor status. Of these, 427 patients had HR+/HER2- primary tumors with concordant metastases, while 71 patients had HR+/HER2- primary tumors with discordant metastases due to HR loss. Loss of HR expression was associated with higher grade (grade 3: discordant 59% vs concordant 38%, p=0.002), lower ER expression (ER ≥50%: discordant 56.8% vs concordant 93.1%, p<0.001) and less frequent dual ER/PR expression in the primary tumor (ER+/PR+: discordant 57.7% vs concordant 80.4%, p<0.001), as well as with shorter median disease-free interval (discordant 40.8m vs concordant 66.1m, p<0.001). Patients with HR loss were more likely to have brain, skin and distant lymph node metastases than patients with HR+ metastases. Of patients with HR loss, 54/71 patients (76.1%) had HR- biopsies at the time of metastatic diagnosis, prior to treatment in the metastatic setting. Six patients had de novo metastatic disease with synchronous HR+ primary tumors and HR- metastases without prior therapy in any setting. Two patients had HR- metastases at metastatic diagnosis with subsequent HR+ metastases consistent with the primary tumor while two additional patients had HR+ and HR- biopsies from distinct metastatic sites taken within two months of each other. Six patients had HR+ metastases at diagnosis and subsequent HR- metastases. A greater proportion of patients with HR loss received chemotherapy in the first-line metastatic setting (71.4% vs 24.8%, p<0.001). Median progression free survival on any first-line therapy was shorter for patients with HR loss (6.4m vs 11.2m, hazard ratio 1.8 (95% CI 1.18-2.74)). Median overall survival from initial diagnosis and metastatic diagnosis were also significantly shorter for patients with HR loss (70.4m vs 123.8m, hazard ratio 1.9 (95% CI 1.42-2.59) and 18.6m vs 45.9m, hazard ratio 2.0 (95% CI 1.49-2.73)). Of patients with HR loss at metastatic diagnosis, those who received endocrine therapy in the metastatic setting had superior outcomes compared to those who did not receive endocrine therapy (21.9m vs 9.6m, hazard ratio 0.303 (95% CI 0.14-0.65)). In multivariate analysis HR loss and lack of dual ER/PR expression on the primary tumor remained associated with inferior survival beyond metastatic diagnosis when accounting for age, race, T stage, nodal status and grade. Conclusion. Discordant HR status in untreated, synchronous breast primary tumors and metastases in patients with de novo metastatic breast cancer, as well as in patients with discordant metastatic biopsies obtained within two months of concordant biopsies, suggests tumor heterogeneity within individual patients irrespective of prior therapy. Improved outcomes with endocrine therapy in the metastatic setting despite loss of HR on the initial metastatic biopsy highlights the continued value of the primary tumor phenotype to guide therapy in the metastatic setting.

Citation Format: Danielle File, Yara Abdou, Amy Wheless, Claire Dees, Lisa Carey. Benefit of endocrine therapy for metastatic breast cancer after loss of hormone receptor expression in patients with HR+/HER2- primary tumors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-17-05.

POS0423 NCOA3 AMPLIFIES PROFIBROTIC TRANSCRIPTIONAL PROGRAMS IN SYSTEMIC SCLEROSIS

Background:

Excessive activation of fibroblasts with a TGFβ-biased gene signature and deposition of extracellular matrix are key features of fibrotic diseases. The mechanisms underlying these transcriptional changes remain poorly understood. Deregulation, mutations and malfunctions of transcriptional co-regulators, which can interact with multiple transcription factors and enable a broad-spectrum regulation of transcriptional networks, have been implicated as driving factors in a large number of diseases and pathologies.

Objectives:

In the present study, we aimed to analyze the role of the co-regulator Nuclear Receptor Co-Activator 3 (NCOA3) in fibroblast activation and tissue fibrosis, and to evaluate a potential interaction of NCOA3 with fibrosis-relevant transcription factors.

Methods:

NCOA3 was inhibited genetically by siRNA transfection and pharmacologically by the SRC3 inhibitor-2 (SI-2). We performed bulk RNASeq of human dermal fibroblasts and in silico transcription factor binding site screening of differentially expressed genes (DEGs). The interaction of NCOA3 and TGFβ-SMAD signaling was analyzed by reporter and CoIP assays.

Results:

The expression of NCOA3 in skin biopsies of SSc patients compared to normal controls demonstrated that SSc fibroblasts express modestly, but significantly reduced levels of NCOA3, which persisted in cultured SSc fibroblasts. Stimulation of normal fibroblasts with chronically high levels of TGFβ as they also occur in fibrotic tissue remodeling strongly decreased NCOA3 expression to a similar extent as in SSc fibroblasts. Furthermore, NCOA3 expression is also deregulated in different murine models of skin fibrosis. To investigate the functional effects of decreased NCOA3 levels, we targeted the expression of NCOA3 in normal fibroblasts. SiRNA-mediated knockdown of NCOA3 ameliorated TGFβ-induced gene expression, collagen release, myofibroblast differentiation and cell proliferation. In contrast, knockdown of NCOA3 had no effects on collagen release, expression of contractile proteins or gene expression in unstimulated fibroblasts, suggesting that NCOA3 is not required for cellular homeostasis. To characterize the molecular mechanisms, we performed RNASeq upon NCOA3 knockdown. We identified 343 significant differentially expressed genes (220 downregulated and 123 upregulated with a Benjamini-Hochberg false discovery rate FDR < 0.25 and fold change > 1.5) between TGFβ-stimulated fibroblasts with and without NCOA3 knockdown (NCOA3-DEGs) including the fibrosis-relevant genes EDNRB, COL5A3, HES1, IL11 or IL33. Functional analysis of the NCOA3-DEGs showed enrichment of pathway terms such as collagen binding and extracellular matrix organization. In silico screening of the promoters of the NCOA3-DEGs for potential transcription factor binding motifs revealed binding motifs of core transcription factors of fibroblast activation and tissue fibrosis such as SMAD2/3/4, RBPJ, ZEB1, TCF4, REL, and SNAIL2 amongst the downregulated NCOA3-DEGs. Experimental validation of our biostatistical results using SMAD3 as example demonstrated a higher percentage of NCOA3-pSMAD3 double-positive fibroblasts in skin sections of SSc patients compared to healthy controls. In addition, knockdown of NCOA3 reduced TGFβ-induced SMAD-reporter activity. Furthermore, stimulation with TGFβ increased the interaction of NCOA3 with SMAD3 as analyzed by co-immunoprecipitation. Simultaneous knockdown of NCOA3 and SMAD3 showed no additional reductions compared to the single knockdowns, suggesting that NCOA3 controls SMAD3-dependent gene transcription under fibrotic conditions. Finally, inhibition of NCOA3 showed anti-fibrotic effects in different murine models of experimental skin and lung fibrosis.

Conclusion:

Our findings characterize NCOA3 as regulator of multiple pro-fibrotic transcription programs. Pharmaceutical inhibition of NCOA3 might be a strategy to interfere simultaneously with several core pro-fibrotic mediators in fibrotic diseases such as SSc.

Acknowledgements:

We thank Lena Summa, Vladyslav Fedorchenko, Wolfgang Espach and Regina Kleinlein for excellent technical assistance.

The study was funded by grants DI 1537/7-1, DI 1537/8-1, DI 1537/9-1 and -2, DI 1537/11-1, DI 1537/12-1, DI 1537/13-1, DI 1537/14-1, DI 1537/17-1, DE 2414/2-1, DE 2414/4-1, and RA 2506/3-1 of the German Research Foundation, SFB CRC1181 (project C01) and SFB TR221/ project number 324392634 (B04) of the German Research Foundation, grants J39, J40 and A64 of the IZKF in Erlangen, grant 2013.056.1 of the Wilhelm-Sander-Foundation, grants 2014_A47, 2014_A248 and 2014_A184 of the Else-Kröner-Fresenius-Foundation, grant 14-12-17-1-Bergmann of the ELAN-Foundation Erlangen, BMBF (Era-Net grant 01KT1801), MASCARA program, TP 2 and a Career Support Award of Medicine of the Ernst Jung Foundation.

Disclosure of Interests:

Clara Dees: None declared, Sebastian Poetter: None declared, Maximilian Fuchs: None declared, Christina Bergmann: None declared, Alexandru-Emil Matei: None declared, Andrea-Hermina Györfi: None declared, Alina Soare: None declared, Andreas Ramming: None declared, Paolo Ceppi: None declared, Georg Schett: None declared, Meik Kunz: None declared, Jörg H.W. Distler Consultant of: Actelion, Active Biotech, Anamar, ARXX, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, Medac, Pfizer, RuiYi and UCB, Grant/research support from: Anamar, Active Biotech, Array Biopharma, ARXX, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB

POS0328 ENGRAILED 1 COORDINATES CYTOSKELETAL ORGANIZATION TO PROMOTE MYOFIBROBLAST DIFFERENTIATION AND FIBROTIC TISSUE REMODELING

Background:

Engrailed 1 (EN1) is a homeodomain-containing transcription factor with essential roles in embryonic development. In most cell types, the expression of EN1 is restricted to embryonic development. However, under pathological conditions, EN1 can be re-expressed to promote phenotypical adaptation. En1 is transiently expressed in the developing dermis of murine embryos in a distinct fibroblast lineage and silenced before birth (1). Former EN1-expressing cells give rise to a subpopulation of fibroblasts that has a high capacity for extracellular matrix production in adult murine skin. The role of EN1 in systemic sclerosis (SSc) was previously not explored.

Objectives:

To study the role of EN1 in the pathological activation of fibroblasts in tissue fibrosis.

Methods:

Bulk RNA-Seq and EN1 or SP1 ChIP-Seq were performed from cultured human dermal fibroblasts. The expression of EN1 was inhibited by siRNA. Cytoskeletal drugs paclitaxel, vinblastin and ROCK inhibitor (Y27632) were used to modulate the cytoskeleton in EN1 knockdown or overexpressing dermal fibroblasts. The role of EN1 in fibroblast activation was evaluated by functional experiments with EN1 knockdown or overexpression in standard 2D culture systems as well as in 3D skin equivalent models. The role of EN1 in skin fibrosis was further studied in En1fl/fl X Col6Cre mice, with fibroblast-specific knockout of En1 in three complementary mouse models: overexpression of a constitutively active TGFß-receptor I (TBRICA), bleomycin-induced skin fibrosis and TSK1 mice.

Results:

Pathologically activated dermal fibroblasts from SSc patients express higher levels of EN1 compared with age and sex matched healthy individuals in the skin and in vitro. TGFβ induces EN1 expression in fibroblasts in a SMAD3-dependent manner both in cultured fibroblasts and in murine skin. Knockdown of EN1 prevents TGFβ-induced fibroblast activation, whereas overexpression of EN1 fosters the pro-fibrotic effects of TGFβ with increased expression of αSMA, stress fibers and collagen. RNA sequencing demonstrates that EN1 induces a pro-fibrotic gene expression profile functionally related to cytoskeleton organization and ROCK activation. In silico analyses of the promoters of En1 target genes coupled with siRNA-mediated knockdown demonstrated that EN1 regulates these pro-fibrotic target genes by modulating the activity of regulatory modules that contain transcription factors of the specificity protein (SP) family. Functional experiments with selective modulators of ROCK and of microtubule polymerization confirm the coordinating role of EN1 on ROCK activity and the re-organization of cytoskeleton during myofibroblast differentiation in both conventional culture systems and 3D skin equivalents. Consistently, mice with fibroblast-specific knockout of En1 demonstrate impaired fibroblast-to-myofibroblast transition, reduced dermal thickening and impaired collagen deposition in the TBRICA, bleomycin-induced and TSK1 models.

Conclusion:

We characterize the homeodomain transcription factor EN1 as a molecular amplifier of TGFβ signaling in myofibroblast differentiation that coordinates cytoskeletal organization in a SP-dependent manner. EN1 might thus be a novel candidate for molecular targeted therapies to interfere with myofibroblast differentiation in fibrotic diseases.

References:

[1]Rinkevich Y, Walmsley GG, Hu MS, Maan ZN, Newman AM, Drukker M, et al. Skin fibrosis. Identification and isolation of a dermal lineage with intrinsic fibrogenic potential. Science. 2015;348(6232):aaa2151.

Disclosure of Interests:

Andrea-Hermina Györfi: None declared, Alexandru-Emil Matei: None declared, Maximilian Fuchs: None declared, Aleix Rius Rigau: None declared, Xuezhi Hong: None declared, ZHU Honglin: None declared, Markus Luber: None declared, Christina Bergmann: None declared, Clara Dees: None declared, Ingo Ludolph: None declared, Raymund Horch: None declared, Oliver Distler Consultant of: Actellion, AbbVie, Acceleron Pharma, Anamar, Amgen, Blade Therapeutics, CSL Behring, ChemomAb, Ergonex, Glenmark Pharma, GSK, Inventiva, Italfarmaco, iQvia, Medac, Medscape, Lilly, Sanofi, Target BioScience, UCB, Bayer, Boehringer Ingelheim, Catenion, iQone, Menarini, Mepha, Novartis, Mitsubishi, MSD, Roche, Pfizer, Georg Schett: None declared, Meik Kunz: None declared, Jörg H.W. Distler Consultant of: Actelion, Active Biotech, Anamar, ARXX, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, Medac, Pfizer, RuiYi and UCB., Grant/research support from: Anamar, Active Biotech, Array Biopharma, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB

OP0272 68GA-FAPI-04 PET/CT STUDY EXTENSION FOR THE ASSESSMENT OF FIBROBLAST ACTIVATION AND RISK EVALUATION IN SYSTEMIC SCLEROSIS-RELATED INTERSTITIAL LUNG DISEASE

Background:

Interstitial lung disease (ILD) is the most common cause of death in systemic sclerosis (SSc). To date, the progression of SSc-ILD is judged by the accrual of lung damage on computed tomography (CT) and functional decline (forced vital capacity). However, this approach does not directly assess the activity of tissue remodeling. Moreover, prediction of the course of ILD in individual SSc patients remains challenging. Fibroblast Activation Protein (FAP) is a specific, ex vivo validated marker for activated fibroblasts.

Objectives:

The aims of this study were: 1. To assess differences in the uptake of 68GA-FAPI 04 in SSc-ILD patients compared to controls, to analyze 2. whether 68GA-FAPI 04 uptake at baseline correlates with other risk factors of disease progression and 3. Whether 68GA-FAPI 04 uptake is associated with the course of SSc-ILD.

Methods:

Between September 2018 and April 2020, 21 patients with SSc-ILD confirmed by HRCT and onset of SSc-ILD within ≤ 5 years or signs of progressive ILD and 21 controls without ILD were consecutively enrolled. All participants underwent 68Ga-FAPI-04 PET/CT imaging and standard-of-care procedures including HRCT and lung function testing (PFT) at baseline. Patients with SSc-ILD patients were followed-up for 6 months with HRCT and PFT. Follow-up 68Ga-FAPI-04 PET/CT scans were obtained in a subset of patients treated with nintedanib. We compared baseline 68Ga-FAPI-04 PET/CT uptake to standard diagnostic tools and currently used predictors of ILD progression. The association of 68Ga-FAPI-04 uptake with changes in FVC was analyzed using mixed-effects models.

Results:

68Ga-FAPI-04 accumulated in fibrotic areas of the lungs in SSc-ILD compared to controls with a median (q1-q3 interval) wlSUVmean of 0.8 (0.6 to 2.1) in the SSc-ILD group and 0.5 (0.4 to 0.5) in the control group (p<0.0001 with Mann-Whitney test) and a median whole lung maximal standardized uptake value (wlSUVmax) of 4.4 (3.05 to 5.2) in the SSc-ILD group compared to 0.7 (0.65 to 0.7) in the control group (p<0.0001). wlFAPI-MAV and wlTL-FAPI were not measurable in control subjects, as no 68Ga-FAPI-04 uptake above background level was observed. In the SSc-ILD group the median wlFAPI-MAV was 254cm3 (163.4 to 442.3) and the median wlTL-FAPI was 183.6 cm3 (98.04 to 960.7). 68Ga-FAPI-04 uptake was higher in patients with extensive disease, with previous ILD progression or high EUSTAR activity scores. Increased 68Ga-FAPI-04 uptake at baseline was associated with progression of ILD independently of extent of involvement on HRCT scan and the forced vital capacity at baseline. In consecutive 68Ga-FAPI-04-PET/CTs, changes in 68Ga-FAPI-04 uptake was concordant with the observed response to the fibroblast-targeting antifibrotic agent nintedanib.

Conclusion:

Our study presents first in human evidence that 68Ga-FAPI-04-fibroblast uptake correlates with fibrotic activity and disease progression in the lungs of SSc-ILD patients and that 68Ga-FAPI-04-PET/CT may be of potential to improve risk assessment of SSc-ILD.

Figure 1.

A and B:68Ga-FAPI-04 PET/CT scan from a patient with SSc-ILD with selective 68Ga-FAPI-04 uptake in fibrotic areas of the left- and right lower lung lobes (red arrows), but not in non-fibrotic areas such as the middle lobe (green arrow). B Corresponding CT component.

Acknowledgements:

We gratefully acknowledge Prof. Uwe Haberkorn (University Hospital Heidelberg and DKFZ, Heidelberg, Germany) and iTheranostics Inc. (Dulles, VA, USA) for providing the precursor FAPI-04.

Disclosure of Interests:

Christina Bergmann: None declared, Jörg H.W. Distler Speakers bureau: Actelion, Anamar, ARXX, Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, and UCB, Grant/research support from: Anamar, Active Biotech, Array Biopharma, ARXX, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB, Christoph Treutlein: None declared, Koray Tascilar Speakers bureau: Gilead sciences GmbH, Pfizer Turkey, UCB Turkey, Anna-Theresa Mueller: None declared, Armin Atzinger: None declared, Alexandru-Emil Matei: None declared, Johannes Knitza: None declared, Andrea-Hermina Györfi: None declared, Anja Lueck: None declared, Clara Dees: None declared, Alina Soare: None declared, Andreas Ramming: None declared, Verena Schönau: None declared, Oliver Distler Speakers bureau: Arxx Therapeutics, Baecon Discovery, Blade Therapeutics,Bayer, Böhringer Ingelheim, Catenion,Competitive Drug Development International Ltd, Corbuspharma, CSL Behring, ChemomAb, Horizon Pharmaceuticals, Ergonex, Galaapagos NV, Glenmark Pharmaceuticals,GSK, Inventiva, Italfarmaco, IQvia, Kymera, Lilly, Medac, Medscape, MSD, Novartis, Pfizer, Roche, Sanofi, Taget Bio Sciencec, UCB, Grant/research support from: Bayer,Böhringer Ingelheim, Mitsubishi Tanabe Pharma, Olaf Prante: None declared, Philipp Ritt: None declared, Theresa Ida Goetz: None declared, Markus Koehner: None declared, Michael Cordes: None declared, Tobias Baeuerle: None declared, Torsten Kuwert Speakers bureau: Honoraria for occasional lectures by Siemens Healthineers, Grant/research support from: Research grant to the Clinic of Nuclear Medicine by this entity covering projects in the field of SPECT/CT, Georg Schett: None declared, Christian Schmidkonz: None declared

Abstract PD14-09: Nci 10013 - A randomized phase 2 study of neoadjuvant carboplatin and paclitaxel, with or without atezolizumab in triple negative breast cancer (TNBC)

Background Inhibition of PD-L1 with atezolizumab combined with chemotherapy has shown acceptable safety and improved survival in patients with metastatic PD-L1 positive triple negative breast cancer (TNBC). Patients with TNBC who do not achieve a pathological complete response (pCR) to neoadjuvant chemotherapy have a high risk of disease recurrence and death. This randomized, open-label, phase 2 trial evaluates neoadjuvant carboplatin and paclitaxel with or without atezolizumab in patients with previously untreated clinical stages II and III TNBC. Methods Women aged ≥18 years with clinical stage T2-T4c, any N, M0 primary tumor by AJCC 7th edition staging TNBC; ECOG PS 0-2; and no prior systemic therapy for the indexed breast cancer were eligible. Patients were randomized in a 1:2 ratio to carboplatin AUC5 q 3 weeks x 4 + paclitaxel 80 mg/m2 q week x 12 (Arm A), or carboplatin AUC5 q 3 weeks x 4 + paclitaxel 80 mg/m2 q week x 12 + atezolizumab 1200 mg q3 weeks x 4 (Arm B). Surgery was 3-6 weeks following neoadjuvant chemotherapy. Adjuvant dose-dense doxorubicin and cyclophosphamide was administered q2 weeks with growth factor support to all patients as per routine care. pCR and tumor infiltrating lymphocyte (TIL) percentages are the co-primary endpoints. pCR-evaluable population includes all eligible women who have been randomized and received at least one dose of combination therapy, while the TIL-evaluable population includes all eligible women who have evaluable TIL percentage after one cycle of therapy. A sample size of 67 (22 in Arm A, and 45 in Arm B) provided 80% power at 1-sided alpha = 0.10 to detect a minimum of 15% difference in TIL and 29% improvement (40% vs. 69%) in pCR, respectively. Herein, we report pCR results in the per protocol modified intent-to-treat population (mITT), which includes all eligible patients who were randomized and received at least one dose of combination therapy. Results Sixty-seven patients were randomized between 8/2017 and 9/2019. Six patients randomized to Arm A withdrew consent; 2 of these received protocol therapy but are excluded from the mITT analyses as they are not evaluable because definitive pathology reports are not available. Median follow up is 6 months (range 0.3 - 12.6 months). Median age is 52 years (range 25 - 78). Forty-three (64.2%) were Caucasian and thirteen (19.4%) were African American. Twenty-five (37.3%) were pre-menopausal. 67.2% and 32.8% had stages II and III disease respectively. Nine (13.4%) had a germline mutation in either BRCA1 or BRCA2. In the mITT population, 3 of 16 patients achieved pCR in Arm A - 18.8% (95% CI 4.0%- 45.6%), versus 25 of 45 patients in Arm B - 55.6% (95% CI 40.0%-70.4%); p value 0.018. pCR in those with BRCA mutations was 50% and 80% in Arm A and Arm B, respectively. Treatment delays were observed in 9 patients (40.9%) in Arm A, and 20 (44.4%) in Arm B; dose reductions occurred in 4 patients (18.1%) in Arm A, and in 6 (13.3%) in Arm B. There were 4 SAEs in Arm A and 10 in Arm B. One patient in Arm B had grade 3 adrenal insufficiency. One patient in Arm B died from recurrent disease during the follow-up period. Conclusions: The addition of atezolizumab to neoadjuvant carboplatin and paclitaxel resulted in an increased pCR rate in patients with clinical stages II and III TNBC. However, the pCR in the control Arm A was lower than expected, possibly due to the absence of neoadjuvant anthracyclines. The high pCR rate observed in the experimental arm of this study is similar to that observed in other neoadjuvant trials utilizing anthracyclines, taxanes, and carboplatin in TNBC. Clinical trial information: NCT02883062.

Citation Format: Foluso O Ademuyiwa, Feng Gao, Ina Chen, Donald W Northfelt, Robert Wesolowski, Mili Arora, Adam Brufsky, Claire Dees, Cesar A Santa-Maria, Roisin M Connolly, Jeremy Force, Alvaro Moreno-Aspitia, Sarah Larson, Elad Sharon, William Gillanders. Nci 10013 - A randomized phase 2 study of neoadjuvant carboplatin and paclitaxel, with or without atezolizumab in triple negative breast cancer (TNBC) [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 PD14-09.

OP0142 FIBROBLAST GROWTH FACTOR RECEPTOR 3 REGULATES THE ACTIVITY OF PROFIBROTIC CYTOKINE AND GROWTH FACTOR PATHWAYS TO DRIVE FIBROBLAST ACTIVATION AND TISSUE FIBROSIS IN SYSTEMIC SCLEROSIS

Background:

Fibroblast growth factor receptor 3 (FGFR3) is a member of the family of different fibroblast growth factor receptors with several ligands called fibroblast growth factors (FGFs) in humans. Each FGFR has different isoforms resulting from natural alternative splice variants. Upon binding FGF ligands, fibroblast growth factor receptors (FGFRs) trigger various intracellular signaling pathways to regulate important biological processes. Systematic evaluation of FGF/FGFR signaling in the context of SSc has not been performed so far.

Objectives:

The aim of this study was to characterize FGFR3/FGF9 signaling in the context of fibroblast activation and to evaluate FGFR3 as a potential molecular target for antifibrotic treatment in SSc.

Methods:

Differential expression profiling of dermal cells from SSc patients and healthy volunteers were performed employing GEArray cDNA microarray. Real-time PCR, Western Blot, immunohistochemistry and immunofluorescence were done in skin tissues and fibroblasts from SSc patients. Selective inhibitors in conjunction with genetic knockdown and knockout strategies were used to target FGFR3 signalingin vitroand in mouse models of SSc: skin fibrosis induced by bleomycin and by overexpression of a constitutively active transforming growth factor receptor 1 (TBR) and tight skin-1 (TSK) mice. Affymetrix gene arrays in dermal fibroblasts from mice with constitutive FGFR3 signaling and mice lacking FGFR3.

Results:

Expression of FGFR3, specifically the isoform FGFR3IIIb and its ligand FGF9, was significantly upregulated in the dermis and dermal fibroblasts of SSc patients as compared to healthy volunteers. Furthermore, an increase of FGFR3 IIIb/FGF9 expression comparable to that in SSc fibroblasts could also be obtained by stimulating normal healthy dermal fibroblasts with transforming growth factor (TGFβ)in vitroand in mice constitutively overexpressing active TGFβ receptor type I.

Transcriptome profiling,in silicoanalysis and functional experiments revealed that FGFR3 synergistigically induces multiple profibrotic pathways including Endothelin-, Interleukin-4- and CTGF-signaling in a CREB-dependent manner. FGFR3 exerts profibrotic effects by modulating phosphorylation of CREB by ERK-, AKT-, CAMK2- and p38-kinases. Activation of FGFR3 in healthy or SSc dermal fibroblasts by stimulation with recombinant FGF9 was sufficient to induce resting fibroblast-to-myofibroblast differentiation along with increased collagen secretion and alpha-SMA production.

Genetic knockout of Fgfr3 abrogates myofibroblast differentiationin vitroand ameliorates skin fibrosis in TSK and TBR mice and in bleomycin-induced fibrosis. Further confirming the translational potential of these findings in the preclinical models of SSc, we demonstrate that pharmacological inactivation of FGFR3 by PD173074 could induce the regression of experimental fibrosis invitroand in bleomycin-challenged, TSK and TBR mice.

Conclusion:

Our findings characterize FGFR3 as an upstream regulator of a network of profibrotic mediators in SSc and thus, we could demonstrate successfully that the targeted inhibition of FGFR3 could inhibit multiple signaling pathwaysin vitroand ameliorated fibrosis in different preclinical models of SSc. These findings may have direct translational implications as FGFR3 inhibitors are currently in development.

Disclosure of Interests:

Debomita Chakraborty: None declared, Honglin Zhu: None declared, Astrid Juengel: None declared, Lena Summa: None declared, Yi-Nan Li: None declared, Christina Bergmann: None declared, Alexandru-Emil Matei: None declared, Thuong Trinh-Minh: None declared, Chih-Wei Chen: None declared, Clara Dees: None declared, Andreas Ramming: None declared, Georg Schett Speakers bureau: AbbVie, BMS, Celgene, Janssen, Eli Lilly, Novartis, Roche and UCB, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Jörg Distler Grant/research support from: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Paid instructor for: Boehringer Ingelheim, Speakers bureau: Boehringer Ingelheim

SAT0291 THE ROLE OF X-LINKED INHIBITOR OF APOPTOSIS PROTEIN (XIAP) IN SYSTEMIC SCLEROSIS

Background:

Pathologic activation of fibroblasts is a central feature of fibrotic tissue disease in Systemic Sclerosis (SSc). Although individual key signaling pathways of fibroblast activation such as transforming growth factor β (TGFβ) and WNT/β-catenin signaling have been identified, the consequences of the concomitant upregulation of these pathways and their crosstalk are incompletely characterized. Given the high medical need, the identification of mutual activation and amplification loops of profibrotic signals is essential to identify novel candidates for antifibrotic therapies. XIAP (X-linked inhibitor of apoptosis protein) is a ubiquitously expressed member of the IAP protein family which are implicated in the regulation of various cellular functions and tissue turnover. XIAP was recently described to be implicated in WNT/β-catenin signaling and TGFβ signaling.

Objectives:

The aim of this study is to characterize the role of XIAP in fibrotic disease.

Methods:

XIAP-expression was analyzed by qPCR, IF and Western blot. XIAP was targeted pharmacologically and with siRNA. The activation of WNT/β-catenin signaling was assessed by analyses of WNT target genes, by TOPflash/FOPflash luciferase reporter assay and in reporter mice.In vivo,XIAP inhibition was analysed in two different models of fibrosis.

Results:

The expression of XIAP is increased in the skin of SSc patients compared to matched healthy individuals with a particular prominent expression in fibroblasts. The overexpression of XIAP is more pronounced in SSc patients with diffuse and active skin fibrosis compared to SSc patients with limited and inactive disease. The overexpression of XIAP is also reflected in several experimental fibrosis models: the model of sclerodermatous graft versus host disease, the model of bleomycin induced skin fibrosis and Topoisomerase I induced fibrosis (TopoI) mice. TGFβ induces the expression of XIAP in vitro and in vivo and treatment with the TGFβ1 receptor antagonist SD208 reverses the TGFβ induced expression of XIAP. Inhibition of XIAP with embelin or siRNA reduces the TGFβ induced activation of fibroblasts with reduced collagen release and reduced expression of myofibroblast markers. In addition, XIAP inhibition reverted the activated fibroblast phenotype in SSc fibroblasts with reduced expression of stress fibers and αSMA. The antifibrotic effects of XIAP inhibition occurred in non-toxic doses as demonstrated by MTT and by TUNEL staining. In vivo, inhibition of XIAP reduced skin fibrosis in the models of bleomycin induced skin fibrosis and in TopoI-induced skin and lung fibrosis as demonstrated by analysis of dermal thickening, dermal hydroxyproline content and by analysis of myofibroblast differentiation. Mechanistically, XIAP inhibition reduced the activation of WNT/β-catenin signaling as demonstrated by TOPflash reporter assays and by the analysis of WNT target genes.

Conclusion:

XIAP is upregulated in SSc fibroblasts and murine SSc models in a TGFβ-dependent manner and promotes fibroblast activation by fostering canonical WNT signaling. Our data suggest that XIAP mediates an amplification loop between TGFβ and WNT/β-catenin signaling. Inhibition of XIAP may thus be a novel approach to target aberrant WNT/β-catenin signaling in fibrotic diseases.

Disclosure of Interests:

Christina Bergmann: None declared, Ludwig Hallenberger: None declared, Benita Merlevede: None declared, Clara Dees: None declared, Chih-Wei Chen: None declared, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Georg Schett Speakers bureau: AbbVie, BMS, Celgene, Janssen, Eli Lilly, Novartis, Roche and UCB, Jörg Distler Grant/research support from: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Paid instructor for: Boehringer Ingelheim, Speakers bureau: Boehringer Ingelheim

SAT0287 AMPLIFICATION OF THE PRO-FIBROTIC JAK2-STAT3 SIGNALING AXIS BY TGFΒ-INDUCED EPIGENETIC SILENCING OF SOCS3

Background:

Tissue fibrosis caused by a pathological activation of fibroblasts is a major hallmark of systemic sclerosis (SSc). Epigenetic gene silencing of anti-fibrotic genes is thought to play a central role to establish the persistently activated phenotype of fibroblasts independent of external stimuli such as TGFβ, which has been identified as key-mediator of fibroblast activation.

Objectives:

The aims of the present study were to investigate whether the aberrant activation of JAK2-STAT3 signaling in fibrosis might be caused by epigenetic silencing of SOCS expression and whether re-establishment of the endogenous, SOCS-dependent control of JAK / STAT signaling may prevent aberrant fibroblast activation and ameliorate tissue fibrosis.

Methods:

The methylation status of SOCS3 in fibroblasts was evaluated by methylation-specific PCR and MeDIP assays. 5-aza-2-deoxycytidine (5-aza) and siRNA was used to inhibit DNA methyltransferases (DNMTs)in vitroandin vivo. Knockdown and overexpression experiments served to analyze the mechanism of action in cultured fibroblasts. Fibroblast-specific knockout mice were additionally used to analyze the role of SOCS3 and DNMTsin vivo.

Results:

Chronically increased levels of TGFβ reduced the expression of SOCS3 in normal fibroblasts to a level also found in SSc fibroblasts. Consistently, the expression of SOCS3 was severely downregulated in skin of SSc patients compared to healthy individuals with only minor differences between limited and diffuse cutaneous SSc. Methylation analyses demonstrated a prominent promoter hypermethylation of SOCS3 in SSc fibroblasts and in normal fibroblasts exposed to persistently high levels of TGFβ. Increased DNMT activity and a time-dependent induction of DNMT3A and DNMT1 expression upon chronic exposure to TGFβ resulted in promoter hypermethylation of SOCS3. Knockdown of SOCS3 induced an SSc-like phenotype in normal dermal fibroblasts with increased activation of JAK2-STAT3 signaling, enhanced expression of myofibroblast markers, increased collagen release, and aggravated experimental tissue fibrosis with increased activation of JAK2-STAT3 signaling. This effect was mimicked by overexpression of mutant JAK2 with mutations in the SOCS3 binding motif. Vice versa, forced overexpression of SOCS3 reduced TGFβ-mediated fibroblast activation and ameliorated the endogenous activation of SSc fibroblasts. Pharmacological inhibition or selective knockdown of DNMTs restored the normal expression of SOCS3, reduced fibroblast activation and collagen release, blocked STAT3-responsive transcription, and exerted potent antifibrotic effects in bleomycin- and TBRIact-induced dermal fibrosis. In addition, treatment with 5-aza or knockdown of either DNMT1 or DNMT3A induced regression of established fibrosis.

Conclusion:

These findings identify a novel pathway of epigenetic imprinting of fibroblasts in fibrotic disease with translational implications for the development of new targeted therapies in fibrotic diseases. We demonstrate that the chronic activation of TGFβ signaling in fibrotic diseases perturbs the epigenetic control of STAT signaling by DNMT-induced silencing of SOCS3 expression. Our data might thus strengthen the scientific rational for targeting DNA methylation in fibrotic diseases.

Disclosure of Interests:

Clara Dees: None declared, Sebastian Poetter: None declared, Yun Zhang: None declared, Christina Bergmann: None declared, xiang zhou: None declared, Markus Luber: None declared, Emmanuel Karouzakis: None declared, Andreas Ramming Grant/research support from: Pfizer, Novartis, Consultant of: Boehringer Ingelheim, Novartis, Gilead, Pfizer, Speakers bureau: Boehringer Ingelheim, Roche, Janssen, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Georg Schett Speakers bureau: AbbVie, BMS, Celgene, Janssen, Eli Lilly, Novartis, Roche and UCB, Jörg Distler Grant/research support from: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Paid instructor for: Boehringer Ingelheim, Speakers bureau: Boehringer Ingelheim

High-resolution axillary ultrasound is a poor prognostic test for determining pathologic lymph node status in patients undergoing neoadjuvant chemotherapy for locally advanced breast cancer

BACKGROUND

The purpose of this study was to evaluate the efficacy of high-resolution axillary ultrasound in detecting axillary lymph node metastases after neoadjuvant chemotherapy in patients with locally advanced breast cancer.

METHODS

Fifty-three patients with stage II or III breast cancer undergoing neoadjuvant chemotherapy who had a physical examination, high-resolution axillary ultrasound, and axillary lymph node dissection from January 1999 to September 2003 were included in this study.

RESULTS

The positive predictive value of the postchemotherapy ultrasound for predicting pathologic nodal involvement was 83%, but the negative predictive value was only 52%. Postchemotherapy physical examination was also poor at predicting pathologic nodal involvement with a positive predictive value of 93% and a negative predictive value of only 58%.

CONCLUSIONS

A negative post-neoadjuvant chemotherapy high-resolution axillary ultrasound or physical examination does not predict pathologic node status, and this test has limited value in this setting.

Treatment of murine cutaneous melanoma with near infrared light

Treatment of cutaneous melanoma (M-3 and B16-F10 implanted in mice) with rapidly-scanned, tightly-focused near infrared light elicits selective destruction of tumor tissue. A single laser treatment yielded complete eradication in >90% of B16-F10 tumors with thicknesses of approximately 3 mm; amelanotic M-3 tumors proved less responsive (ca 25% clearance rate). In addition to local tumor destruction, laser treatment of B16-F10 tumors in immunocompetent mice stimulated enhanced cytokine levels (interleukin-2 and interleukin-10) within treated tumor tissues and rejection of tumor cells upon a subsequent challenge dose. Such an antitumor immune response may lead to improved outcomes at both the treatment site and at sites of distant metastasis.

Differential conformational requirements for activation of G proteins and the regulatory proteins arrestin and G protein-coupled receptor kinase in the G protein-coupled receptor for parathyroid hormone (PTH)/PTH-related protein

After stimulation with agonist, G protein-coupled receptors (GPCRs) activate G proteins and become phosphorylated by G protein-coupled receptor kinases (GRKs), and most of them translocate cytosolic arrestin proteins to the cytoplasmic membrane. Agonist-activated GPCRs are specifically phosphorylated by GRKs and are targeted for endocytosis by arrestin proteins, suggesting a connection between GPCR conformational changes and interaction with GRKs and arrestins. Previously, we showed that by substitution of histidine for residues at the cytoplasmic side of helix 3 (H3) and helix 6 (H6) of the parathyroid hormone (PTH) receptor (PTHR), a zinc metal ion-binding site is engineered that prevents PTH-stimulated G(s) activation (Sheikh, S. P., Vilardaga, J.-P., Baranski, T. J., Lichtarge, O., Iiri, T., Meng, E. C., Nissenson, R. A., and Bourne, H. R. (1999) J. Biol. Chem. 274, 17033-17041). These data suggest that relative movements between H3 and H6 are critical for G(s) activation. Does this molecular event play a similar role in activation of GRK and arrestin and in PTHR-mediated G(q) activation? To answer this question, we utilized the two previously described mutant forms of PTHR, H401 and H402, which contain a naturally present histidine residue at position 301 in H3 and a second substituted histidine residue at positions 401 and 402 in H6, respectively. Both mutant receptors showed inhibition of PTH-stimulated inositol phosphate and cAMP generation in the presence of increasing concentrations of Zn(II). However, the mutants showed no Zn(II)-dependent impairment of phosphorylation by GRK-2. Likewise, the mutants were indistinguishable from wild-type PTHR in the ability to translocate beta-arrestins/green fluorescent protein to the cell membrane and were also not affected by sensitivity to Zn(II). These results suggest that agonist-mediated phosphorylation and internalization of PTHR require conformational switches of the receptor distinct from the cAMP and inositol phosphate signaling state. Furthermore, PTHR sequestration does not appear to require G protein activation.

Fas-Fas ligand-mediated apoptosis within aqueous during idiopathic acute anterior uveitis

PURPOSE

Despite ocular immune privilege, (auto)immune-mediated acute anterior uveitis (AAU) is relatively common. However, although relapses of AAU are usually self-limiting, possible regulatory mechanisms remain undefined in humans. Experimentally, Fas-Ligand (FasL)-mediated apoptosis of Fas+ inflammatory cells contributes to the immune privilege within the anterior chamber and provides an explanation for the success of corneal allograft transplantation. Therefore, whether such mechanisms regulate the immune response in AAU was investigated.

METHODS

Aqueous and peripheral blood samples from consecutive patients presenting with idiopathic AAU were obtained with consent. Leukocytic phenotype was analyzed by flow cytometry, and apoptosis was determined by both flow cytometry and TdT-dUTP terminal nick-end labeling analysis. Presence of soluble Fas and FasL was determined by western blot analysis and enzyme-linked immunosorbent assay and compared with control aqueous from patients undergoing cataract surgery. The ability of the aqueous to induce apoptosis in a Fas+ Jurkat cell line was also determined.

RESULTS

During AAU aqueous-infiltrating Fas+ cells included CD3+ T cells and granulocytes, whereas FasL+ cells comprised predominantly of non-CD3+ T cells. Higher levels of functional soluble FasL were found in aqueous of AAU patients than in normal aqueous, capable of inducing apoptosis in 68.9% +/- 7.6% of Fas+ lymphoid cells. Compared with peripheral blood, the CD4+ T cells infiltrate within aqueous showed significantly increased CD69 and CD25(IL-2r) expression. Flow cytometric analysis of aqueous showed that 9.32% +/- 1.2% of infiltrating non-granulocyte CD45+ cells were apoptotic, confirmed as T cells on subsequent three-color flow cytometric analysis.

CONCLUSIONS

Taken together with published experimental data, the present study provides evidence for FasL-mediated apoptotic cell death contributing to the local immune regulation of ocular inflammatory disease and provides a mechanism to account for the self-limiting clinical course of AAU.

Immunosuppressive treatment of choroidal neovascularization associated with endogenous posterior uveitis

OBJECTIVE

To determine whether resolution of choroidal neovascularization (CNV), a recognized sight-threatening complication of endogenous posterior uveitis, and maintenance of vision could be achieved with immunosuppression.

PATIENTS AND METHODS

Fourteen patients (17 eyes) with CNV associated with endogenous posterior uveitis were enrolled in an open study. Ages ranged from 5 to 51 years. Three eyes had extrafoveal CNV, 6 juxtafoveal, and 8 subfoveal. Three patients were treated with a single course of oral corticosteroids, 2 had additional cyclosporine for up to 2 years, and 9 continued to receive a low-dose regimen of a combination of immunosuppressive drugs.

RESULTS

After a median follow-up of 15 months (range, 7 months to 6 1/2 years), 9 of 17 eyes had an improvement in visual acuity; 6 remained within 1 Snellen line of initial visual acuity, and 2 had lost 2 Snellen lines. Angiographically, CNV resolved in 13 eyes, resolved then recurred in 3, and improved but persisted in 4.

CONCLUSION

These results support a role for immunosuppressive therapy in the treatment of CNV associated with endogenous posterior uveitis.

Xenoestrogens significantly enhance risk for breast cancer during growth and adolescence

Breast cancer is one of the most common forms of cancer observed in women, and endogenous estrogen is thought to play a major role in its development. Because of this, any conditions or exposures which enhance estrogenic responses would result in an increased risk for breast cancer. The role of xenoestrogenic compounds, such as DDT, in the etiology of breast cancer is still very controversial. In the following paper we discuss recently-published observations by ourselves and others which indicate that xenoestrogens may play a significant role in the development of breast cancer. Specifically, we hypothesize that during periods of high growth rates and during breast development the sensitivity of breast cells to estrogenic compounds is sufficiently great for xenoestrogens to significantly enhance risk for breast cancer.

Interactions of phosducin with the subunits of G-proteins. Binding to the alpha as well as the betagamma subunits

The high affinity interactions of phosducin with G-proteins involve binding of phosducin to the G-protein betagamma subunits. Here we have investigated whether phosducin interacts also with G-protein alpha subunits. Interactions of phosducin with the individual subunits of Go were measured by retaining phosducin-G-protein subunit complexes on columns containing immobilized anti-phosducin antibodies. Both the alpha and the beta subunits of trimeric Go were specifically retained by the antibodies in the presence of phosducin. This binding was almost completely abolished for both subunits following protein kinase A-mediated phosphorylation of phosducin and was reduced, more for alpha than for beta subunits, by the stable GTP analog guanosine 5'-(3-O-thio)triphosphate. Isolated alphao was also retained on the columns in the presence of phosducin but not in the presence of protein kinase A-phosphorylated phosducin. Likewise, purified G-protein betagamma subunit complexes as well as purified alpha subunits of Go and Gt were precipitated together with His6-tagged phosducin with nickel-agarose; this co-precipitation occurred concentration-dependently, with apparent affinities for phosducin of 55 nM (Gbetagamma), 110 nM (alphao), and 200 nM (alphat). In functional experiments, the steady state GTPase activity of isolated alphao was inhibited by phosducin by approximately 60% with an IC50 value of approximately 300 nM, whereas the GTPase activity of trimeric Go was inhibited by approximately 90% with an IC50 value of approximately 10 nM. Phosducin did not inhibit the GTP-hydrolytic activity of isolated alphao as measured by single-turnover assays, but it inhibited the release of GDP from alphao; the rate constant of GDP release was decreased approximately 40% by 500 nM phosducin, and the inhibition occurred with an IC50 value for phosducin of approximately 100 nM. These data suggest that phosducin binds with high affinity to G-protein betagamma subunits and with lower affinity to G-protein alpha subunits. We propose that the alpha subunit-mediated effects of phosducin might increase both the extent and the rapidity of its inhibitory effects compared with an action via the betagamma subunit complex alone.

Simultaneous two-photon activation of type-I photodynamic therapy agents

The excitation and emission properties of several psoralen derivatives are compared using conventional single-photon excitation and simultaneous two-photon excitation (TPE). Two-photon excitation is effected using the output of a mode-locked titanium: sapphire laser, the near infrared output of which is used to promote nonresonant TPE directly. Specifically, the excitation spectra and excited-state properties of 8-methoxypsoralen and 4'-aminomethyl-4,5,8-trimethylpsoralen are shown to be equivalent using both modes of excitation. Further, in vitro feasibility of two-photon photodynamic therapy (PDT) is demonstrated using Salmonella typhimurium. Two-photon excitation may be beneficial in the practice of PDT because it would allow replacement of visible or UV excitation light with highly penetrating, nondamaging near infrared light and could provide a means for improving localization of therapy. Comparison of possible laser excitation sources for PDT reveals the titanium: sapphire laser to be exceptionally well suited for nonlinear excitation of PDT agents in biological systems due to its extremely short pulse width and high repetition rate that together provide efficient PDT activation and greatly reduced potential for biological damage.

Estrogenic and DNA-damaging activity of Red No. 3 in human breast cancer cells

Exposure to pesticides, dyes, and pollutants that mimic the growth promoting effects of estrogen may cause breast cancer. The pesticide DDT and the food colorant Red No. 3 were found to increase the growth of HTB 133 but not estrogen receptor (ER) negative human breast cells (HTB 125) or rat liver epithelial cells (RLE). Red No. 3, beta-estradiol, and DDT increase ER site-specific DNA binding to the estrogen response element in HTB 133 cells and increase cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells. Site-specific DNA binding by p53 in RLE, HTB 125, HTB 133, and MCF-7 cells was increased when they were treated with Red No. 3, which suggests that cellular DNA was damaged by this colorant. Red No. 3 increased binding of the ER from MCF-7 cells to the estrogen-responsive element. Consumption of Red No. 3, which has estrogenlike growth stimulatory properties and may be genotoxic, could be a significant risk factor in human breast carcinogenesis.