Treatment of Thymoma and Thymic Carcinoma with Proton Beam Therapy: Outcomes from the Proton Collaborative Group Prospective Registry

PURPOSE/OBJECTIVE(S)

Given the generally long natural history of thymic malignancies, proton beam therapy (PBT) is advocated to minimize the risk of long-term toxicities to mediastinal organs. Adverse events (AE) and long-term clinical outcomes for this population have not been well-characterized.

MATERIALS/METHODS

The Proton Collaborative Group registry (NCT01255748), a multi-institutional prospective database of academic and community proton centers in the US, was queried for patients with thymomas and thymic carcinomas treated with PBT. Patients with recurrent/metastatic disease, non-thymic histology, received either prior or palliative radiotherapy (dose < 40 Gy RBE) were excluded. Overall survival (OS) and local control (LC) were estimated using Kaplan-Meier methods.

RESULTS

A total of 97 patients were identified in the PCG registry. After applying relevant exclusion criteria, 70 patients from 12 proton centers treated from 2011-2021 were included for analysis. Median follow-up length was 16 months. Median age was 58.5 years (IQR 46-63), and 60% were female. 81.4% had a diagnosis of thymoma, and 18.6% thymic carcinoma. 59 patients underwent surgical resection. 11 were treated with definitive PBT, of which 5 received concurrent chemotherapy. Median dose was 54 Gy RBE (range 41.4 - 70 Gy RBE), median number of fractions was 30 (range 21 - 38). 73.4% received pencil beam scanning and 23% uniform scanning PBT. Treatment was overall well-tolerated: a single patient developed grade 4 pneumonitis. Grade 3 AEs were seen in 3 patients - dyspnea, anorexia, and heart failure. Highest grade toxicity experienced was grade 2 for 47.1% and grade 1 for 42.9% of patients. 3-year overall survival (OS) was 82.6% for the entire cohort. 3-year OS was 94% for resected/adjuvant cohort and 35.6% in the non-surgical/definitive cohort. 3-year local control (LC) was 91.7% for the entire cohort. By surgery/margin status, 3-year LC was 96.8% in patients with close or negative margins (a single failure in a patient with close margins), whereas 3-year LC was 55.1% for patients with positive margins/unresectable disease.

CONCLUSION

Thymic malignancies treated with PBT appear to have favorable outcomes, especially in the adjuvant setting, in this cohort representing the largest series of such patients.

An analog-AI chip for energy-efficient speech recognition and transcription

Models of artificial intelligence (AI) that have billions of parameters can achieve high accuracy across a range of tasks1,2, but they exacerbate the poor energy efficiency of conventional general-purpose processors, such as graphics processing units or central processing units. Analog in-memory computing (analog-AI)3-7 can provide better energy efficiency by performing matrix-vector multiplications in parallel on 'memory tiles'. However, analog-AI has yet to demonstrate software-equivalent (SWeq) accuracy on models that require many such tiles and efficient communication of neural-network activations between the tiles. Here we present an analog-AI chip that combines 35 million phase-change memory devices across 34 tiles, massively parallel inter-tile communication and analog, low-power peripheral circuitry that can achieve up to 12.4 tera-operations per second per watt (TOPS/W) chip-sustained performance. We demonstrate fully end-to-end SWeq accuracy for a small keyword-spotting network and near-SWeq accuracy on the much larger MLPerf8 recurrent neural-network transducer (RNNT), with more than 45 million weights mapped onto more than 140 million phase-change memory devices across five chips.

0659 A Safe and Precise Tongue Base Surgery for Obstructive Sleep Apnea: Real-Time Intraoperative Ultrasound-Assisted Transoral Robotic Surgery

Introduction

Lingual artery (LA) injury is a devastating complication of tongue base surgery. Compared with the anatomic findings of computed tomography angiography (CTA), intraoperative blade of mouth gag might change the thickness of base of tongue (BOT) and anatomy of LA. We aimed to investigate the position of LA in the BOT with intraoperative ultrasound (IOU) imaging during transoral robotic surgery (TORS), and evaluate the bleeding complications when assisted with / without IOU.

Methods

Adult obstructive sleep apnea (OSA) patients who received TORS in BOT resection were recruited since 2016. Assessment tools were pre-op over-night hospital polysomnography (PSG) and anatomy-based Friedman Staging System. Ultrasound imaging was utilized to identify anatomic parameters of LA in BOT, including distance to midline, arterial depth and diameter.

Results

Ninety-three OSA patients (82 male, 88.2%) were analyzed. The mean age was 42.2±10.0 years old and body mass index was 29.2±4.5 kg/m2. The average apnea hypopnea index (AHI) was 58.1±21.4 events/hour. There were 66 (71.0%), 24 (25.8%) and 3 (3.2%) patients in Friedman stages II, III and IV, respectively. Seventy patients underwent TORS with IOU had shorter operation time (191.7±3.8 minutes) than 23 patients without IOU (220.1±6.6 minutes), less total blood loss (11.3±10.8 versus 19.6±26.7 ml), and more BOT tissue reduction volume (7.1±2.5 versus 3.9±1.6 ml). Significant predictors of arterial depth were higher AHI level during rapid-eye-movement (REM) sleep stage (p=0.038), bigger tonsil size (p=0.034) and more elevated Friedman tongue position (p=0.012). Postoperative complication associated with LA injury was not found in the patients with use of IOU.

Conclusion

When tongue retracted with blade, the distance to midline and depth of LA were altered in BOT. With IOU assisted, surgeon could identify LA position confidently. It is expectable to maximize efficiency and minimize catastrophic bleeding complications when OSA patients received TORS in BOT resection.

Support

nil

0461 Blunted Baroreflex Sensitivity and Reduced Morning Parasympathetic Activity in Sleep-Onset Insomnia

Introduction

Insomnia is a risk factor for hypertension and cardiovascular events, and this association is strongest for sleep-onset insomnia. However, little is known about insomnia on cardiovascular modulation, especially soon after morning awakening, the peak period of time for cardiovascular incidents. This study explored morning cardiovascular function in individuals with sleep-onset insomnia by analysing heart rate variability, blood pressure variability, and baroreflex sensitivity.

Methods

Sleep structure of the participants (15 good sleepers and 13 individuals with sleep-onset insomnia) was measured by laboratory polysomnography, followed by continuous recordings of the participant’s blood pressure and heart rate for 10 min in the morning.

Results

When compared to the good sleepers, the insomnia group showed significant reductions in total sleep time, a longer sleep-onset latency, and reduced sleep efficiency. The sleep structure, including durations of sleep stages, numbers of awakenings and arousal index did not differ between the groups. After morning awakening (averaged time: 12.33 ± 10.48 min), the shorter R-R intervals, lower total power, and lower high-frequency power of heart rate variability were observed among individuals with sleep-onset insomnia, compared with good sleepers. Elevated slopes of systolic and diastolic blood pressure, as well as lower baroreflex sensitivity, were also shown in the insomnia group. Indices of sympathetic activity, including low-frequency percentage of heart rate variability or low-frequency power of blood pressure variability, did not differ between the groups.

Conclusion

Weak vagal activity and blunted baroreflex sensitivity were evident among sleep-onset insomnia. These findings indicate difficulty in initiating sleep, without significant sleep fragmentation, can independently affect morning cardiovascular function. This study provides a possible link between sleep-onset insomnia and risk of cardiovascular events.

Support

N/A

Combination of arginine, glutamine, and omega-3 fatty acid supplements for perioperative enteral nutrition in surgical patients with gastric adenocarcinoma or gastrointestinal stromal tumor (GIST): A prospective, randomized, double-blind study

Background

Perioperative enteral nutrition (EN) enriched with immune-modulating substrates is preferable for patients undergoing major abdominal cancer surgery. In this study, perioperative EN enriched with immune-modulating nutrients such as arginine, glutamine, and omega-3 fatty acids was evaluated for its anti-inflammatory efficacy in patients with gastric adenocarcinoma or gastrointestinal stromal tumor (GIST) receiving curative surgery.

Materials and Methods

This prospective, randomized, double-blind study recruited 34 patients with gastric adenocarcinoma or gastric GIST undergoing elective curative surgery. These patients were randomly assigned to the study group, receiving immune-modulating nutrient-enriched EN, or the control group, receiving standard EN from 3 days before surgery (preoperative day 3) to up to postoperative day 14 or discharge. Laboratory and inflammatory parameters were assessed on preoperative day 3 and postoperative day 14 or at discharge. Adverse events (AEs) and clinical outcomes were documented daily and compared between groups.

Results

No significant differences were observed between the two groups in selected laboratory and inflammatory parameters, or in their net change, before and after treatment. AEs and clinical outcomes, including infectious complications, overall complications, time to first bowel action, and length of hospital stay after surgery, were comparable between treatment groups (all P > 0.05).

Conclusion

Immune-modulating nutrient-enriched EN had no prominent immunomodulation effect compared with that of standard EN.

Scaling law for excitons in 2D perovskite quantum wells

Ruddlesden–Popper halide perovskites are 2D solution-processed quantum wells with a general formula A₂A’_n-1M_nX_3n+1, where optoelectronic properties can be tuned by varying the perovskite layer thickness (n-value), and have recently emerged as efficient semiconductors with technologically relevant stability. However, fundamental questions concerning the nature of optical resonances (excitons or free carriers) and the exciton reduced mass, and their scaling with quantum well thickness, which are critical for designing efficient optoelectronic devices, remain unresolved. Here, using optical spectroscopy and 60-Tesla magneto-absorption supported by modeling, we unambiguously demonstrate that the optical resonances arise from tightly bound excitons with both exciton reduced masses and binding energies decreasing, respectively, from 0.221 m₀ to 0.186 m₀ and from 470 meV to 125 meV with increasing thickness from n equals 1 to 5. Based on this study we propose a general scaling law to determine the binding energy of excitons in perovskite quantum wells of any layer thickness.

Hybrid 2D layered perovskites are solution-processed quantum wells whose optoelectronic properties are tunable by varying the thickness of the inorganic slab. Here Blancon et al. work out a general behavior for dependence of the excitonic properties in layered 2D perovskites.

Outcome of elective withdrawal of anti-tumour necrosis factor-α therapy in patients with Crohn's disease in established remission

BACKGROUND AND AIMS

Outcomes of cessation of anti-TNF therapy for Crohn's disease (CD) in clinical and/or endoscopic remission in routine clinical practice is uncertain. This study aimed to evaluate clinical outcomes and factors associated with relapse in CD patients following formal disease assessment and elective anti-TNF withdrawal.

METHODS

Prospective observational study of CD patients in whom anti-TNF therapy was stopped electively after ≥12months and follow-up of ≥6months. Investigations at assessment prior to cessation included ≥1 of clinical assessment, endoscopic and/or imaging. Relapse was defined as recurrent symptoms of CD requiring medical or surgical therapy.

RESULTS

Eighty-six patients received anti-TNF for a median duration of 23 (12-80) months for severe active luminal (70%), fistulating perianal (25.5%) and other fistulating disease (4.5%). Relapse rates at 90,180 and 365days were 4.7%, 18.6% and 36%, respectively. If anti-TNF dose escalation occurred 6months prior to withdrawal, 88% (7/8) relapsed. Based on multivariate analysis, risk factors for relapse include ileocolonic disease at diagnosis and previous anti-TNF therapy. An elevated faecal calprotectin (FC) is likely to predict relapse (p=0.02), with a PPV of 66.7% at >50μg/g. Of 36 patients who relapsed, 31 were retreated with anti-TNF, with an overall recapture rate of 93%.

CONCLUSION

Relapse rates at 1year following elective withdrawal of anti-TNF are 36%, with high retreatment response rate. Predictors of relapse include ileocolonic involvement, previous anti-TNF therapy and raised FC. Endoscopic/radiologic assessment prior to cessation of therapy does not appear to predict those at lower risk of relapse.

High sensitivity of taper-based Mach-Zehnder interferometer embedded in a thinned optical fiber for refractive index sensing

A taper-based Mach-Zehnder interferometer (MZI) embedded in a thinned optical fiber is demonstrated as a highly sensitive refractive index (RI) sensor. A RI sensitivity of 2210.84 nm/RIU (refractive index unit) is obtained at the external RI of 1.40, which is ten times higher than that of normal taper- and long-period fiber grating (LPFG)-based sensors. The sensitivity can be further improved by decreasing the diameter of the thinned fiber and increasing the interferometer length of the MZI. The proposed MZIs have lower temperature sensitivities compared with normal fiber sensors, which is a desirable merit for RI sensors to reduce the cross sensitivity caused by thermal drift.

Abstract 3278: Novel knock-in mice expressing human/mouse chimeric endoglin (ENG; CD105) develop normally and will be valuable for evaluating clinical application of anti-human ENG antibodies

The major objective of this study is to develop a novel animal model to facilitate optimal clinical application of anti-human ENG (huENG) monoclonal antibodies (mAbs) to treat cancer patients. ENG is a proliferation-associated homodimeric cell membrane antigen of endothelial cells and leukemia cells. It is strongly expressed on angiogenic vascular endothelium in tumors and also expressed in lymphatic vessels in tumors. Furthermore, ENG is a TGF-β coreceptor and essential for angiogenesis/vascular development. Mice lacking ENG die from defective vascular development. Mutations in the huENG gene are associated with hereditary hemorrhagic telangiectasia type 1 (HHT1) which is characterized by vascular malformations and recurrent bleeding. huENG shows a relatively restricted expression pattern in tissues and cells. We hypothesized that huENG is a safe and effective target in vascular-targeting antiangiogenic therapy (VTAT). Clinical trials of a chimeric anti-huENG mAb c-SN6j (also known as TRC105) are in progress (ClinicalTrials.gov Identifier: NCT00582985 and NCT01090765). The major obstacle in animal model studies of anti-huENG mAbs is that most anti-huENG mAbs do not react with mouse ENG or mouse endothelial cells. To overcome this obstacle, we generated knock-in mice expressing human/mouse chimeric ENG. We designed the chimeric vectors to contain huENG gene segments of desired location and length so that the expressed huENG protein contains desired epitopes. Nevertheless, the major concern was that the generated knock-in mice might suffer from defective vascular development or HHT-like symptoms if the chimeric ENG does not function properly in mice. We generated two types of knock-in mice containing different sizes of huENG gene. In both cases, mice develop normally and show no sign of HHT-like symptoms in the homozygous mice. Tumors of 4T1 breast cancer cells and Colon26 colon cancer cells were generated in the knock-in mice to test expression of chimeric ENG protein in the tumor microvessels. Immunohistochemical staining of the tumors using several anti-huENG mAbs showed that the tumor microvessels express desired epitopes of huENG protein which are candidate targets for VTAT. The epitopes defined by these mAbs have been mapped. This novel knock-in mouse model will be useful for evaluating antitumor efficacy of many anti-huENG mAbs. In addition, this model will be useful for evaluating appropriate combination of an anti-huENG mAb with other anticancer agents to achieve optimal antitumor efficacy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3278. doi:10.1158/1538-7445.AM2011-3278

Endoglin-targeted cancer therapy

Vascular-targeting antiangiogenic therapy (VTAT) of cancer can be advantageous over conventional tumor cell targeted cancer therapy if an appropriate target is found. Our hypothesis is that endoglin (ENG; CD105) is an excellent target in VTAT. ENG is selectively expressed on vascular and lymphatic endothelium in tumors. This allows us to target both tumor-associated vasculature and lymphatic vessels to suppress tumor growth and metastasis. ENG is essential for angiogenesis/vascular development and a co-receptor of TGF-β. Our studies of selected anti-ENG monoclonal antibodies (mAbs) in several animal models and in vitro studies support our hypothesis. These mAbs and/or their immunoconjugates (immunotoxins and radioimmunoconjugates) induced regression of preformed tumors as well as inhibited formation of new tumors. In addition, they suppressed metastasis. Several mechanisms were involved in the suppressive activity of the naked (unconjugated) anti-ENG mAbs. These include direct growth suppression of proliferating endothelial cells, induction of apoptosis, ADCC (antibody-dependent cell-mediated cytotoxicity) and induction of T cell immunity. To facilitate clinical application, we generated a human/mouse chimeric anti-ENG mAb termed c-SN6j and performed studies of pharmacokinetics, toxicology and immunogenicity of c-SN6j in nonhuman primates. No significant toxicity was detected by several criteria and minimal immune response to the murine part of c-SN6j was detected after multiple i.v. injections. The results support our hypothesis that c-SN6j can be safely administered in cancer patients. This hypothesis is supported by the ongoing phase 1 clinical trial of c-SN6j (also known as TRC105) in patients with advanced or metastatic solid cancer in collaboration with Tracon Pharma and several oncologists (NCT00582985).

Anti-endoglin monoclonal antibodies are effective for suppressing metastasis and the primary tumors by targeting tumor vasculature

Anti-metastatic activity of an antitumor agent is exceedingly important because metastasis is the primary cause of death for most solid cancer patients. In this report, we show that 3 anti-endoglin (ENG) monoclonal antibodies (mAbs) SN6a, SN6j and SN6k which define individually distinct epitopes of ENG of tumor vasculature are capable of suppressing tumor metastases in the multiple metastasis models. The metastasis models were generated by i.v., s.c. (into flank) or mammary gland fat pad injection of 4T1 murine mammary carcinoma cells and splenic injection of two types of colon26 murine colorectal carcinoma cells. Individual mAbs were injected i.v. via the tail vein of mice. SN6a and SN6j effectively suppressed the formation of metastatic colonies of 4T1 in the lung in all of the three 4T1 metastatic models. In addition, these mAbs were effective for suppressing the primary tumors of 4T1 in the skin and mammary fat pad. These mAbs effectively suppressed microvessel density and angiogenesis in tumors as measured by the Matrigel plug assay in mice. No significant side effects of the administered mAbs were detected. Furthermore, SN6a and SN6j extended survival of the tumor-bearing mice. SN6j, SN6k and their immunoconjugates with deglycosylated ricin A-chain were all effective for suppressing hepatic metastasis of colon26. The findings in the present study are clinically relevant in view of the ongoing clinical trial of a humanized (chimerized) form of SN6j.

Anti-tumor activity of an anti-endoglin monoclonal antibody is enhanced in immunocompetent mice

In the present study, we investigated the mechanisms by which anti-endoglin (EDG; CD105) monoclonal antibodies (mAbs) suppress angiogenesis and tumor growth. Antihuman EDG mAb SN6j specifically bound to murine endothelial cells and was internalized into the cells in vitro. SN6j effectively suppressed angiogenesis in mice in the Matrigel plug assay. We found that SN6j is more effective for tumor suppression in immunocompetent mice than in SCID mice. We hypothesized that T cell immunity is important for effective antitumor efficacy of SN6j in vivo. To test this hypothesis, we investigated effects of CpG oligodeoxynucleotides (ODN) and depletion of CD4(+) T cells and/or CD8(+) T cells on antitumor efficacy of SN6j in mice. Systemic (i.v.) administration of a relatively small dose (0.6 mug/g body weight/dose) of SN6j suppressed growth of established s.c. tumors of colon-26 in BALB/c mice and improved survival of the tumor-bearing mice. Addition of CpG ODN to SN6j synergistically enhanced antitumor efficacy of SN6j. In contrast, such enhancing effects of CpG ODN were not detected in SCID mice. Antitumor efficacy of SN6j in BALB/c mice was abrogated when CD4(+) T cells and/or CD8(+) T cells were depleted; effect of CD8(+) T cell depletion was stronger. Interestingly, CD4-depletion decreased tumor growth while CD8-depletion enhanced tumor growth in the absence of SN6j. SN6j induced apoptosis in human umbilical vein endothelial cells in a dose-dependent manner which indicates an additional mechanism of antiangiogenesis by SN6j. (c) 2008 Wiley-Liss, Inc.

Effective anti-angiogenic therapy of established tumors in mice by naked anti-human endoglin (CD105) antibody: differences in growth rate and therapeutic response between tumors growing at different sites

We investigated anti-angiogenic/vascular targeting therapy of established tumors in immunocompetent mice using an anti-human endoglin (EDG; CD105) monoclonal antibody (mAb) SN6j. SN6j weakly cross-reacted with murine endothelial cells but reacted neither with colon-26 murine colon carcinoma cells nor with 4T1 murine mammary carcinoma cells. Systemic administration of naked (unconjugated) SN6j showed significant growth suppression of established tumors of colon-26 and 4T1 cells in immunocompetent BALB/c mice (P<0.05). Moreover, the overall survival rate of SN6j-treated mice was significantly higher than that of control IgG-treated mice (P<0.01). During these studies, we found that two different types of tumor formed in BALB/c and immunodeficient SCID mice when three different types of tumor cells (colon-26, 4T1 and MCF-7 human breast cancer cells) were inoculated subcutaneously. One type of tumor grew in the skin-side tissue (i.e., epidermis, corium, or subcutis), and mainly invaded into the corium and epidermis. The other type grew in the muscle-side tissue (i.e., fascia, muscle, or peritoneum/pleura). We termed the former SS tumors and the latter MS tumors. MS tumors grew faster than SS tumors. This differential growth of MS and SS tumors was observed in three different animal models, i.e., colon-26 tumors and 4T1 tumors in BALB/c mice, and MCF-7 tumors in SCID mice. In the therapeutic study of colon-26 and 4T1 tumors with SN6j, MS tumors were less responsive to therapy than SS tumors although SN6j showed significant antitumor efficacy against both tumors (P<0.05). The results show that antitumor therapy can yield different therapeutic outcomes depending on the tumor growth sites even for the same tumor. A differential survival between mice with the two types of tumor was also observed when mice were untreated (P<0.01).

Antiangiogenic chimeric anti-endoglin (CD105) antibody: pharmacokinetics and immunogenicity in nonhuman primates and effects of doxorubicin

We generated a human/mouse chimeric antibody c-SN6j of human IgG1 isotype from a murine anti-human endoglin (EDG) monoclonal antibody (mAb) SN6j that suppressed angiogenesis, tumor growth and metastasis in mice. We determined pharmacokinetics (PKs) and immunogenicity of c-SN6j in monkeys after multiple i.v. injections. A dose-escalation study was performed by administration of c-SN6j into six monkeys at the dose of 1 mg, 3 mg and 10 mg per kg body weight. In addition, both c-SN6j (3 mg/kg) and doxorubicin (0.275 mg/kg) were injected into two monkeys. c-SN6j and doxorubicin were injected twice a week for 3 weeks. We developed a unique and sensitive ELISA by sequentially targeting the common and idiotypic epitopes of c-SN6j-Fv to quantify plasma c-SN6j. Application of the ELISA showed that increasing the c-SN6j dose resulted in a proportional increase in the circulating c-SN6j after the first injection. In addition, the estimated area under the curve (AUC) for the first injection of c-SN6j is proportional to dose. We carried out detailed analyses of PKs of c-SN6j during and after the repeated injections. Our model of PKs fitted the empirical data well. Addition of doxorubicin modulated the PK parameters. We developed two ELISAs to separately determine the immune responses to the murine part and the human part of c-SN6j in monkeys. Interestingly, the murine part induced a weaker immune response than the human part. Doxorubicin potentiated the immune responses. Increasing the dose of c-SN6j increased plasma levels of c-SN6j but did not increase the immune responses to c-SN6j.

Synergy between anti-endoglin (CD105) monoclonal antibodies and TGF-beta in suppression of growth of human endothelial cells

Endoglin (CD105) is a proliferation-associated cell membrane antigen of endothelial cells and strongly expressed in the angiogenic vasculature of solid tumors. Endoglin is essential for angiogenesis/vascular development and an ancillary transforming growth factor beta (TGF-beta) receptor. Certain anti-endoglin monoclonal antibodies (mAbs), termed SN6 series mAbs, inhibited angiogenesis, tumor growth and metastasis in mice. We investigated the mechanisms by which anti-endoglin mAbs suppress growth of proliferating endothelial cells. We found that 4 SN6 series mAbs suppressed growth of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner in the absence of any effector cells or complement. Significant differences in the growth suppression between the 4 anti-endoglin mAbs defining different epitopes were observed. These differences were not determined by antigen-binding avidities of the mAbs. Combination of TGF-beta1 and each of the 4 anti-endoglin mAbs exerted synergistic growth suppression of HUVECs. Binding of anti-endoglin mAbs to endoglin-expressing cells did not block the subsequent binding of TGF-beta1. Conversely, preincubation of HUVECs with TGF-beta1 did not change cell surface expression of endoglin. The present results suggest that direct suppression of the endothelial cell growth by SN6 series mAbs is one of the underlying mechanisms by which anti-endoglin mAbs exert antiangiogenic and tumor-suppressive activity in vivo. The results further suggest that TGF-beta1 plays an important role in the in vivo antiangiogenic efficacy of anti-endoglin mAbs by synergistically enhancing the activity of these mAbs. Further studies of the present novel findings may provide valuable information about the functional roles of endoglin and anti-endoglin mAbs in the TGF-beta-mediated cell regulation.

Angiogenesis and metastasis marker of human tumors

Tumor growth and metastasis are dependent on angiogenesis. Therefore, certain angiogenesis markers may be useful as metastasis markers and/or the targets for antiangiogenic therapy. We and others have been studying endoglin(EDG; CD105) for such purposes. EDG is a proliferation-associated antigen of endothelial cells and essential for angiogenesis. In addition, EDG is a component of the transforming growth factor(TGF)-beta receptor complex. Expression of EDG is up-regulated in tumor-associated angiogenic vasculature compared with normal tissue vasculature. Microvessel density detected for EDG expression in breast cancer tissues showed a statistically significant correlation with overall and disease-free survival. In addition, elevated serum EDG was associated with metastasis in patients with colorectal, breast, and other solid tumors. On the other hand, We have been targeting EDG on tumor vasculature to suppress tumor growth and metastasis by systemic(i.v.) administration of anti-EDG monoclonal antibodies(mAbs) and immunoconjugates(IMCs). To thid end, we have been using three animal models, i.e., severe combined immunodeficient(SCID) mouse model of MCF-7 human breast cancer, human skin/SCID mouse chimera model bearing MCF-7 tumor, and syngeneic metastasis model of colon-26 adenocarcinoma cells in BALB/c mice. In addition, antiangiogenic activities of anti-EDG mAbs and IMCs were evaluated in mice using the dorsal air sac assay. The IMCs were prepared by coupling deglycosylated ricin A-chain or 125I to individual anti-EDG mAbs. These anti-EDG IMCs and mAbs showed substantial antitumor efficacy and antimetastatic activities without showing severe toxicity. Recently, we generated a recombinant human/mouse chimeric anti-EDG mAb to facilitate clinical application of the mAb.

Endothelin-1 increases glucose transporter glut1 mRNA accumulation in 3T3-L1 adipocytes by a mitogen-activated protein kinase-dependent pathway

The mechanism of enhancing glucose transport by prolonged endothelin-1 (ET-1) treatment of 3T3-L1 adipocytes was examined. Western and Northern blot analyses indicated that ET-1 increased the amount of both GLUT1 protein and mRNA. The degradation rate of GLUT1 mRNA as measured in the presence of actinomycin D, nevertheless, was not significantly altered by ET-1. Whereas various inhibitors for distinct signalling pathways were tested, only the mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059, was found to decrease significantly the enhancing effect of ET-1. Similar extent of inhibition was observed in cells pretreated with pertussis toxin (PT). Immunoblot analysis revealed that ET-1 may stimulate a transient phosphorylation of p42/p44 MAPK and both PT and PD98059 inhibited this stimulation. In addition, the effect of ET-1 on GLUT1 mRNA accumulation was inhibited by PD98059 and cycloheximide, implying that a trans-activation was involved. Taken together, these results suggest that ET-1 may induce GLUT1 gene expression by a MAPK-dependent mechanism.