Comparison of transcatheter edge-to-edge and surgical repair in patients with functional mitral regurgitation using a meta-analytic approach

Background

Evidence regarding favorable treatment of patients with functional mitral regurgitation (FMR) using transcatheter edge-to-edge repair (TEER) is constantly growing. However, there is only few data directly comparing TEER and surgical mitral valve repair (SMVr).

Aims

To compare baseline characteristics, short-term and 1-year outcomes in FMR patients undergoing mitral valve (MV) TEER or SMVr using a meta-analytic approach.

Methods

Systematic database search identified 1,703 studies reporting on TEER or SMVr for treatment of FMR between January 2010 and December 2020. A meta-analytic approach was used to compare outcomes from single-arm and randomized studies based on measures by means of their corresponding 95% confidence intervals (CI). Statistical significance was assumed if CIs did not overlap. A total of 21 TEER and 37 SMVr studies comprising 4,304 and 3,983 patients were included.

Results

Patients in the TEER cohort presented with higher age (72.0 ± 1.7 vs. 64.7 ± 4.7 years, p < 0.001), greater burden of comorbidities like hypertension (p < 0.001), atrial fibrillation (p < 0.001), lung disease (p < 0.001) and chronic renal disease (p = 0.005) as well as poorer left ventricular ejection fraction (30.9 ± 5.7 vs. 36.6 ± 5.3%, p < 0.001). In-hospital mortality was significantly lower with TEER [3% (95%-CI 0.02-0.03) vs. 5% (95%-CI 0.04-0.07)] and 1-year mortality did not differ significantly [18% (95%-CI 0.15-0.21) vs. 11% (0.07-0.18)]. NYHA [1.06 (95%-CI 0.87-1.26) vs. 1.15 (0.74-1.56)] and MR reduction [1.74 (95%-CI 1.52-1.97) vs. 2.08 (1.57-2.59)] were comparable between both cohorts.

Conclusion

Despite considerably higher age and comorbidity burden, in-hospital mortality was significantly lower in FMR patients treated with TEER, whereas a tendency toward increased 1-year mortality was observed in this high-risk population. In terms of functional status and MR grade reduction, comparable 1-year results were achieved.

Edge-to-edge mitral valve repair improves concomitant high-grade tricuspid regurgitation

Background

Mitral regurgitation (MR) and tricuspid regurgitation (TR) often occur simultaneously and symptoms of biventricular heart failure can overlap. There is currently no consensus on the management of combined MR and TR.

Purpose

To evaluate the impact of TR on echocardiographic and functional outcome after M-TEER.

Methods

740 patients underwent M-TEER for moderate-to-severe MR at our center from 2010 to 2021. Patients were analyzed according to severity of concomitant TR: low-grade TR (grade ≤ I (trace - mild)), moderate TR (grade II) and high-grade TR (grade III - V (severe - torrential)). After M-TEER, patients were followed up for 12 months and their echocardiographic and functional outcome was evaluated.

Results

Low-grade TR was present in 279 patients (37.7%), moderate TR in 170 patients (23.0%) and high-grade TR in 291 patients (39.3%) at the time of M-TEER procedure. Patients with moderate to high-grade TR had higher morbidity resulting in higher EuroSCORE II and STS-Score. At baseline more patients had MR grade ≥III in the high-grade TR group (92.8% vs. 87.1% in the low-grade TR group; p=0.023).

Procedural success of M-TEER was achieved similarly in all groups (98.2% vs. 97.6% vs. 95.9%, p=0.22). At discharge 87.6% of patients with low-grade TR and 80.9% of patients with high-grade TR had residual MR grade ≤I (p=0.036). Residual MR grade ≥III was present in 6.0% of low-grade TR patients and 10.5% of high-grade TR patients at discharge (p=0.062). 3 months after M-TEER residual MR ≥III increased to 9.4% vs. 13.4% (p=0.23) and after 12 months further increased to 12.3% vs. 15.3%, respectively (p=0.52).

TR grade decreased rapidly and consistently after M-TEER. 3 months after the procedure only 48.0% of high-grade TR patients still had TR grade ≥III (p&lt;0.001). After 12 months this proportion declined to 46.8% (p=0.99).

High-grade TR patients had significantly higher mortality (21.5% vs. 18.2% vs. 11.1%, p=0.003) up to 12 months after M-TEER. However, TR-grade ≥III did not independently predict mortality (HR 1.326, 95% CI 0.623–2.824, p=0.46).

Conclusion

M-TEER patients with concomitant moderate to high-grade TR had higher morbidity at baseline compared to low-grade TR patients. M-TEER was safe and effective in MR reduction independent of concomitant TR severity. However, high-grade TR patients had an increased risk for mortality after M-TEER, but high-grade TR did not independently predict adverse outcome. After M-TEER TR grade decreased rapidly and significantly in the high-grade TR group.

Funding Acknowledgement

Type of funding sources: None.

Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Percutaneous edge-to-edge therapy with PASCAL or MitraClip: a multicenter propensity score matched comparison

Background

The MitraClip is the worldwide established transcatheter edge-to-edge repair system with over 100,000 treated patients. The recently approved PASCAL repair system is well adopted in the field of percutaneous mitral regurgitation (MR) treatment with growing acceptance both in mitral and tricuspid valves. The aim of this retrospective multicenter study was to compare the Edwards' PASCAL System with the Abbott MitraClip System in terms of procedural results and short-term outcome.

Methods

We retrospectively evaluated patient data of three high volume German centers that performed percutaneous edge to edge procedures either with the MitraClip or the PASCAL repair system. Primary endpoint was the amount of MR reduction. Secondary endpoints were residual MR at discharge, technical success, device success and 30-day mortality.

Results

Between 2018 and 2020 a total of 412 procedures were performed in the three centers. 216 cases were performed with the MitraClip compared to 196 procedures done with the PASCAL repair system. Patients were male in 55.6% of the cases (50.5% in the MitraClip cohort compared to 61.2% in the PASCAL cohort, p=0.028), mean Logistic Euro-Score II was 4.42 (3.58 in the MitraClip and 3.23 in the PASCAL cohort, p=0.038) and reduced LVEF beyond 45% was seen in 42.6% of the cases (49.5% in the MitraClip compared to 35.3% in the PASCAL cohort, p=0.004). Severe MR at baseline was seen in 98.5% in the MitraClip cohort compared to 98.6% in the PASCAL cohort, p=0.909). Mean number of implanted devices was 1.41±0.56 in the MitraClip cohort and 1.37±0.55 in the PASCAL cohort (p=0.401). Procedures were successfully conducted with both edge-to-edge systems (device success rate 93.2% in the MitraClip cohort and 94.0% in the PASCAL cohort, p=0.775), leading to comparably good results (final MR ≤2 in 94.4% with the MitraClip compared to 95.9% with the PASCAL system, p=0.448) and very good results (final MR ≤1 in 72.6% in the MitraClip compared to 79.5% in the PASCAL cohort, p=0.102).

After propensity score matching for adjustment of major differences among the two treatment strategies (including age, gender, MR etiology, EROA, Severe MR (III and IV), reduced LVEF and Mitral Valve orifice area) the achieved mean MR reduction remains comparable (2.29±0.82 with the MitraClip compared to 2.46±0.82 with the PASCAL system, p=0.191). In multivariate regression analysis STS Score independently correlates with a very good final result while device choice did not show a significant impact in this cohort.

Conclusion

In this retrospective multicenter study both the MitraClip and PASCAL system performed excellent with comparable procedural success rates. Achieved final average reduction of MR Grade was 2.29±0.82 with the MitraClip and 2.46±0.82 with the PASCAL system.

Funding Acknowledgement

Type of funding sources: None.

Multicentre experience with the transcatheter valve repair system for tricuspid regurgitation

Background

Tricuspid regurgitation (TR) is associated with high morbidity and mortality, but many patients are ineligible for surgical treatment due to age and co-morbidities. As a consequence, transcatheter treatment techniques have evolved over the last years. Leaflet repair is one of the most commonly used techniques and has recently gained commercial approval for dedicated TR treatment. The device offers the possibility for independent leaflet grasping and a central spacer can bridge larger coaptation gaps. The hitherto evidence is mainly based on compassionate use data. This is the first report on commercial use in a multicenter study with a large patient cohort and long-term follow-up.

Purpose

To investigate safety and efficacy of the leaflet repair system in the treatment of TR in a commercial use setting.

Methods

We retrospectively collected clinical and imaging data from all consecutive patients undergoing leaflet repair for TR at four tertiary care centres. A core laboratory analysis of the echocardiographic data has been performed. Baseline, procedural and follow-up data has been included in the analysis.

Results

A total of 155 patients, treated between February 2019 and February 2021 has been included (mean age 77±8 years, 52% female). Mean STS score was 7.7±6.7%. TR was of functional etiology in the majority (82%) of patients and was severe or higher graded in 87% (mean EROA 68±47 mm2). Patients were highly symptomatic with exertional dyspnea NYHA functional class III/IV in 91%. Technical success was achieved in 97% and TR was successfully reduced to ≤2+ in 90% of patients (p&lt;0.001). Three cases of intra-procedural single-leaflet device attachment (SLDA) occurred, and there was one case of access site bleeding requiring emergency surgery. There were no other in-hospital adverse events. Follow-up was available for 120 patients (median follow-up 182, IQR 54–356 days). TR reduction was sustained in most patients with TR ≤2+ in 83% (p&lt;0.001). We found indications for right ventricular (RV) remodeling with a significant decrease of RV end-diastolic diameter (57±8 mm vs. 52±10 m, p&lt;0.001). Dimensions of the inferior vena cava decreased significantly as a sign of less congestion (27±8 mm vs. 23±7 mm, p=0.004). During the follow-up period, 15 patients (10%) died, of which 7 (5%) were of a cardiovascular cause. Symptomatic improvement was significant with 66% of patients in NYHA functional class I or II at follow-up (p&lt;0.001) and an improvement of the 6-meter walking distance (228±120 m vs. 276±121 m, p=0.001).

Conclusion

Transcatheter treatment of TR with the leaflet repair system is feasible and safe. According to our data, technical success rate is high and procedural complications are rare. Patients experienced significant symptomatic improvement at follow-up with echocardiographic sustained TR reduction. Furthermore, there are indications for RV remodeling and reduced congestion.

Funding Acknowledgement

Type of funding sources: None. Improving valve function and symptoms

Severe tricuspid regurgitation worsens prognosis outcome after edge-to-edge mitral valve repair

Introduction

MitraClip has been well established for treatment of severe mitral regurgitation (MR). MR and tricuspid regurgitation (TR) often occur simultaneously and symptoms of biventricular heart failure can overlap. While it has been shown that TR grade regression can be achieved through repair of MR1, presence of moderate to severe TR can increase all-cause mortality after MitraClip2. There is currently no consensus on the management of combined MR and TR. We evaluated the impact of TR on echocardiographic and functional outcome after MitraClip.

Methods

370 patients underwent MitraClip for moderate to severe MR at our center from 2010 to 2018. Patients were dichotomized into low grade TR (grade &lt;I - I (trace - mild)) and high grade TR (grade III - V (severe - torrential)). Moderate TR (grade II) was excluded. After MitraClip for MR, patients were followed up for 12 months and their echocardiographic and functional outcome was evaluated. Use of diuretic drugs throughout 12 month follow-up was registered.

Results

Low grade TR (&lt;I - I) occurred in 225 patients (67.0%), high grade TR (III - V) was present in 111 patients (33.0%). 34 patients (9.2%) with moderate TR (II) were excluded. Patients with high grade TR had an increased morbidity (higher age, worse renal function, higher prevalence of atrial fibrillation, higher levels of natriuretic peptides, increased left atrial and right heart diameters, higher TR gradient). These patients also received significantly higher doses of torasemid (33.5±36.7 mg vs. 21.6±20.9 mg, p=0.003) and furosemid (163.4±155.5 mg vs. 75.8±72.3 mg, p=0.01). Average grade of MR at baseline was similar in both groups (2.9±0.46 vs. 2.8±0.5, p=0.66).

Procedural success of MR repair was achieved similarly in both groups (96.4% vs. 96.9%, p=0.82) and residual MR grade immediately after device implantation was comparable (p=0.61). However, recurrent MR in the high grade TR group increased during follow up, while MR further decreased in the low grade TR group (3 months: 1.24±0.7 vs. 1.16±0.7, p=0.5; 12 months: 1.46±0.93 vs. 1.12±0.61, p=0.04). Accordingly, use of diuretic drugs after 12 months rose in the high grade TR group while it did not change or even decreased in the low grade TR group (torasemid: 40.2±48.4 mg vs. 24.1±30.0 mg, p=0.04; furosemid: 197.5±251.0 mg vs. 67.1±81.8 mg, p=0.22).

Kaplan-Meier-Analysis showed significantly higher mortality (24.9 vs. 14.1%, p=0.01), higher risk for heart failure induced rehospitalisation (25,4 vs. 12,5%, p=0.005) and for major adverse cardiac and cerebrovascular events (MACCE: 42.3 vs. 29.1%, p=0.008) in the high grade TR group after 12 months.

Conclusion

MitraClip patients for MR with concomitant high grade TR (≥ III) had an increased morbidity at baseline compared to low grade TR patients. By MitraClip comparable reduction of MR was achieved. However, during 12 month follow-up in the high grade TR group recurrent MR occurred more often while use of diuretics increased.

Funding Acknowledgement

Type of funding sources: None.

Near-infrared fluorescence imaging platform for quantifying in vivo nanoparticle diffusion from drug loaded implants

Drug loaded implants are a new, versatile technology platform to deliver a localized payload of drugs for various disease models. One example is the implantable nanoplatform for chemo-radiation therapy where inert brachytherapy spacers are replaced by spacers doped with nanoparticles (NPs) loaded with chemotherapeutics and placed directly at the disease site for long-term localized drug delivery. However, it is difficult to directly validate and optimize the diffusion of these doped NPs in in vivo systems. To better study this drug release and diffusion, we developed a custom macroscopic fluorescence imaging system to visualize and quantify fluorescent NP diffusion from spacers in vivo. To validate the platform, we studied the release of free fluorophores, and 30 nm and 200 nm NPs conjugated with the same fluorophores as a model drug, in agar gel phantoms in vitro and in mice in vivo. Our data verified that the diffusion volume was NP size-dependent in all cases. Our near-infrared imaging system provides a method by which NP diffusion from implantable nanoplatform for chemo-radiation therapy spacers can be systematically optimized (eg, particle size or charge) thereby improving treatment efficacy of the platform.

Performance of computer vision in vivo flow cytometry with low fluorescence contrast

Detection and enumeration of circulating cells in the bloodstream of small animals are important in many areas of preclinical biomedical research, including cancer metastasis, immunology, and reproductive medicine. Optical in vivo flow cytometry (IVFC) represents a class of technologies that allow noninvasive and continuous enumeration of circulating cells without drawing blood samples. We recently developed a technique termed computer vision in vivo flow cytometry (CV-IVFC) that uses a high-sensitivity fluorescence camera and an automated computer vision algorithm to interrogate relatively large circulating blood volumes in the ear of a mouse. We detected circulating cells at concentrations as low as 20 cells/mL. In the present work, we characterized the performance of CV-IVFC with low-contrast imaging conditions with (1) weak cell fluorescent labeling using cell-simulating fluorescent microspheres with varying brightness and (2) high background tissue autofluorescence by varying autofluorescence properties of optical phantoms. Our analysis indicates that CV-IVFC can robustly track and enumerate circulating cells with at least 50% sensitivity even in conditions with two orders of magnitude degraded contrast than our previous in vivo work. These results support the significant potential utility of CV-IVFC in a wide range of in vivo biological models.

Nanoparticle-based brachytherapy spacers for delivery of localized combined chemoradiation therapy

PURPOSE

In radiation therapy (RT), brachytherapy-inert source spacers are commonly used in clinical practice to achieve high spatial accuracy. These implanted devices are critical technical components of precise radiation delivery but provide no direct therapeutic benefits.

METHODS AND MATERIALS

Here we have fabricated implantable nanoplatforms or chemoradiation therapy (INCeRT) spacers loaded with silica nanoparticles (SNPs) conjugated containing a drug, to act as a slow-release drug depot for simultaneous localized chemoradiation therapy. The spacers are made of poly(lactic-co-glycolic) acid (PLGA) as matrix and are physically identical in size to the commercially available brachytherapy spacers (5 mm × 0.8 mm). The silica nanoparticles, 250 nm in diameter, were conjugated with near infrared fluorophore Cy7.5 as a model drug, and the INCeRT spacers were characterized in terms of size, morphology, and composition using different instrumentation techniques. The spacers were further doped with an anticancer drug, docetaxel. We evaluated the in vivo stability, biocompatibility, and biodegradation of these spacers in live mouse tissues.

RESULTS

The electron microscopy studies showed that nanoparticles were distributed throughout the spacers. These INCeRT spacers remained stable and can be tracked by the use of optical fluorescence. In vivo optical imaging studies showed a slow diffusion of nanoparticles from the spacer to the adjacent tissue in contrast to the control Cy7.5-PLGA spacer, which showed rapid disintegration in a few days with a burst release of Cy7.5. The docetaxel spacers showed suppression of tumor growth in contrast to control mice over 16 days.

CONCLUSIONS

The imaging with the Cy7.5 spacer and therapeutic efficacy with docetaxel spacers supports the hypothesis that INCeRT spacers can be used for delivering the drugs in a slow, sustained manner in conjunction with brachytherapy, in contrast to the rapid clearance of the drugs when administered systemically. The results demonstrate that these spacers with tailored release profiles have potential in improving the combined therapeutic efficacy of chemoradiation therapy.

Toward lower contrast computer vision in vivo flow cytometry

There are many applications in biomedical research where detection and enumeration of circulating cells (CCs) is important. Existing techniques involve drawing and enriching blood samples and analyzing them ex vivo. More recently, small animal "in vivo flow cytometry" (IVFC) techniques have been developed, where fluorescently-labeled cells flowing through small arterioles (ear, retina) are detected and counted. We recently developed a new high-sensitivity IVFC technique termed "Computer Vision(CV)-IVFC". Here, large circulating blood volumes were monitored in the ears of mice with a wide-field video-rate near-infrared (NIR) fluorescent camera. Cells were labeled with a membrane dye and were detected and tracked in noisy image sequences. This technique allowed enumeration of CCs in vivo with overall sensitivity better than 10 cells/mL. However, an ongoing area of interest in our lab is optimization of the system for lower-contrast imaging conditions, e.g. when CCs are weakly labeled, or in the case higher background autofluorescence with visible dyes. To this end, we developed a new optical flow phantom model to control autofluorescence intensity and physical structure to better mimic conditions observed in mice. We acquired image sequences from a series of phantoms with varying levels of contrast and analyzed the distribution of pixel intensities, and showed that we could generate similar conditions to those in vivo. We characterized the performance of our CV-IVFC algorithm in these phantoms with respect to sensitivity and false-alarm rates. Use of this phantom model in optimization of the instrument and algorithm under lower-contrast conditions is the subject of ongoing work in our lab.

Evaluation of the SIOPEN semi-quantitative scoring system in planar simpatico-adrenal MIBG scintigraphy in children with neuroblastoma

Neuroblastoma is the most common malignancy in children comprising 7.6% of all infantile cancers. MIBG scintigraphy is a mandatory neuroblastoma diagnostic test, which is among others methods, semi-quantified by the SIOPEN method. The aim of this study was to test both the skeletal and the soft tissue segments of the SIOPEN scoring method in the diagnostic milieu and to correlate them with the Curie score. Since there is little knowledge of their diagnostic power, the following variables were tested: VMA, HVA, LDH, and MYCN, ferritin, bone marrow infiltration, the INSS and the INPC classification. The cross-sectional study with repeated measurements of 143 scintigrams was performed on 76 pediatric patients with suspected or proven neuroblastoma, who had been referred to the Center for Nuclear Medicine of the Clinical Center of Serbia in the period 2007-2012. The range of the SIOPEN soft tissue scores was 0-5. The range of the SIOPEN skeletal scores was 0-57. The range of the Curie scores was 0-26. The skeletal SIOPEN scores were significantly higher in bone marrow positive children, in children with pathologically elevated urinary VMA levels and in children having a more advanced clinical stage. There was no difference in the SIOPEN soft tissue score due to higher VMA levels, or depending on the clinical stage and positive bone marrow assessment. There was no difference between the SIOPEN skeletal and soft tissue scores on one hand and the histological grade of the tumor; elevated or normal levels of HVA, LDH, NSE and ferritin, or the presence or absence of MYNC amplification in the neuroblastoma cell line, on the other hand. The results of both SIOPEN scores showed a high linear correlation with the Curie score. The conclusion is that the soft tissue segment of the SIOPEN score needs further elucidation in a more controlled milieu. Excellent correlation between all segments of the two semi-quantitative scoring methods speaks in favor of the application of the complete SIOPEN scoring system in every day mIBG scanning.

Abstract 4917: Smart brachytherapy spacers eluting nanoencapsulated radiosensitizers for chemo-radiation therapy

Introduction: We have developed a new approach for chemoradiation therapy (CRT), termed Biological In-Situ Image Guided Radiation Therapy BIS-IGRT, which involves the coating of spacers routinely used during prostate I-125-based brachytherapy with radiosensitizing drugs (e.g. docetaxel DTX and gold nanoparticles). This approach provides localized in-situ delivery of the sensitizer to the tumor and avoids the toxicity associated with current systemic delivery of radiosensitizers. BIS-IGRT adds radiosensitization capability to the standard brachytherapy procedure providing sustained delivery and drug concentration and with minimal additional inconvenience to the patient. Thereby BIS-IGRT improves the therapeutic ratio of radiation therapy without introducing additional patient interventions over current brachytherapy procedures.

Methods: We have fabricated a nanoparticles based smart ‘INCeRT’ (Implantable Nanoplatform for Chemo-Radiation Therapy) implant for localized delivery of radiosensitizing nanoparticles/ drugs in prostate cancer in conjunction with brachytherapy. These implants are physically similar to the clinically used brachytherapy spacers but have the added capability of imaging and local drug delivery. We have fabricated INCeRT spacers with biocompatible and biodegradable polymer, PLGA impregnated with nanoparticles encapsulating imaging probe (Cyanine 7.5) and chemotherapeutic drug, docetaxel (DTX). Using a similar approach, we have also fabricated PLGA spacers impregnated with high Z (atomic number) gold nanoparticles (Hi-Z-CuRE: High Z-Customizable Radiotherapy Enhancement) for effectively boosting the radiation dose locally. The morphology, composition and nanoparticle's distribution inside the spacers was studied by SEM (scanning electron microscopy) and EDS (Energy-dispersive X-ray spectroscopy). Further, preliminary in vivo imaging experiments with subcutaneous prostate cancer tumored mice implanted with INCeRT spacers showed a size dependent diffusion of nanoparticles from the spacers in the tumor matrix. Also, from in vivo therapeutic studies with these spacers showed a sustained and slow release of the DTX from the spacers and showed a better response in suppressing the tumor as opposed to control mice with saline injections. Further experiments for studying the combined chemo-radiation therapy are underway.

Conclusions: BIS-IGRT is a powerful approach to locally radio-sensitize the prostate to enable prostate cancer (PCa) cure with the use of lower radiation doses, thereby leading to less rectal toxicity. This new treatment approach would be of crucial benefit for patients with local relapse who require salvage radiotherapy but have reached their radiotherapy normal tissue dose limits. This work was supported partially by NSF-DGE-0965843, HHS/1U54CA151881 CORE1, 1R03 CA164645-01 and a seed grant from the BWH Biomedical Research Institute.

Note: This abstract was not presented at the meeting.

Citation Format: Rajiv Kumar, Jodi Belz, Stacey Markovic, Mark Niedre, Wilfred Ngwa, Houari Korideck, Robert Cormack, Paul Nguyen, Anthony D'Amico, Mike Makrigiorgos, Srinivas Sridhar. Smart brachytherapy spacers eluting nanoencapsulated radiosensitizers for chemo-radiation therapy. [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 4917. doi:10.1158/1538-7445.AM2014-4917

A computer vision approach to rare cell in vivo fluorescence flow cytometry

Noninvasive enumeration of rare circulating cell populations in small animals is of great importance in many areas of biomedical research. In this work, we describe a macroscopic fluorescence imaging system and automated computer vision algorithm that allows in vivo detection, enumeration and tracking of circulating fluorescently-labeled cells from multiple large blood vessels in the ear of a mouse. This imaging system uses a 660 nm laser and a high sensitivity electron-multiplied charge coupled device camera (EMCCD) to acquire fluorescence image sequences from relatively large (∼5 × 5 mm(2) ) imaging areas. The primary technical challenge was developing an automated method for identifying and tracking rare cell events in image sequences with substantial autofluorescence and noise content. To achieve this, we developed a two-step image analysis algorithm that first identified cell candidates in individual frames, and then merged cell candidates into tracks by dynamic analysis of image sequences. The second step was critical since it allowed rejection of >97% of false positive cell counts. Overall, our computer vision IVFC (CV-IVFC) approach allows single-cell detection sensitivity at estimated concentrations of 20 cells/mL of peripheral blood. In addition to simple enumeration, the technique recovers the cell's trajectory, which in the future could be used to automatically identify, for example, in vivo homing and docking events.

Abstract 1594: Sustained release of drug eluting nanoparticles from implantable devices for loco-regional chemoradiation therapy

Systemic chemotherapy is often used with radiation therapy in the management of prostate, cervix and lung cancer patients, but leads to severe systemic toxicities. We have introduced a new modality of loco-regional chemoradiation therapy termed in-situ image guided radiation therapy (BIS-IGRT) that offers the potential to deliver planned, localized and sustained delivery of chemotherapy agent, without systemic toxicities, as part of routine minimally invasive image guided radiation therapy procedures. Such image guided chemoradiation therapy requires characterization of the drug distribution produced by implantable drug eluters. This work presents imaging based means to measure temporal and spatial properties of diffusion distributions around spacers coated with dye-loaded nanoparticles.

The distribution of 250nm silica nanoparticles (NP) conjugated to Cyanine 7.5 dye was evaluated with a custom built high-speed near-infrared small animal imaging platform providing 0.1 millimeter spatial resolution with &gt;1Hz image acquisition rate. A brachytherapy spacer loaded with the Cy7.5/silica NP was injected subcutaneously on the left hind flank of a mouse and one was inserted into a xenograft tumor on the opposite flank as part of an approved animal research protocol. The mouse was imaged more than 36 days.

The in vivo imaging experiments show that the area of high signal increases with time suggesting that NP accumulate in the vicinity of a spacer without diffusing to the rest of the body. The spatial and temporal characteristics of NP accumulation indicate that a BIS-IGRT approach may provide an effective means to improve the therapeutic ratio of brachytherapy.

Conclusion: In-vivo measurements demonstrate that NP remain resident in the vicinity of the implanted eluting spacers with accumulation over times appropriate to improve brachytherapy's therapeutic ratio. Future work will optimize the NP and substrate properties of an implantable spacer to attain the optimal chemotherapy distributions for simultaneous placement during image guided brachytherapy implants.

We acknowledge partial support from NSF DGE 0965843 and HHS/5U54CA151881-02.

Citation Format: Rajiv Kumar, Jodi Belz, Stacey Markovic, Tej Jadhav, Paul Nguyen, Mark Niedre, Anthony DAmico, Mike Makrigiorgos, Robert Cormack, Srinivas Sridhar. Sustained release of drug eluting nanoparticles from implantable devices for loco-regional chemoradiation therapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1594. doi:10.1158/1538-7445.AM2013-1594

Continuous monitoring of functional activities using wearable, wireless gyroscope and accelerometer technology

The development of functional activity monitors (FAMs) will allow rehabilitation researchers and clinicians to evaluate treatment efficacy, to monitor compliance to exercise instructions, and to provide real time feedback in the treatment of movement disorders during the performance of daily activities. The purpose of the present study was to develop and test a small sized wearable FAM system comprised of three sensors positioned on the sternum and both thighs, wireless Bluetooth transmission capability to a smartphone, and computationally efficient activity detection algorithms for the accurate detection of functional activities. Each sensor was composed of a tri-axial accelerometer and a tri-axial gyroscope. Computationally efficient activity recognition algorithms were developed, using a sliding window of 1 second, the variability of the tilt angle time series and power spectral analysis. In addition, it includes a decision tree that identifies postures such as sitting, standing and lying, walking at comfortable, slow and fast speeds, transitions between these functional activities (e.g, sit-to-stand and stand-to-sit), activity duration and step frequency. In a research lab setting the output of the FAM system, video recordings and a 3D motion analysis system were compared in 10 healthy young adults. The results show that the agreement between the FAM system and the video recordings ranged from 98.10% to 100% for all postures, transfers and walking periods. There were no significant differences in activity durations and step frequency between measurement instruments.

Examination of Immune Competence in Breast Cancer Patients at Six Months Post Surgery and Adjuvant Therapy through Assessment of T Cell and Dendritic Cell Functionality

It has long been known that immune suppression is induced by the presence of a tumor, resulting in compromised T cell and dendritic cell (DC) functionality. What is not well understood is how soon the immune system recovers normal functionality following surgical removal of tumors and adjuvant therapy. This timing is of critical importance, as the effectiveness of therapeutic immune strategies relies on optimal presentation of antigens and activation of T cells. Blood from breast cancer patients was collected prior to surgery and at 3 and 6 months post adjuvant therapy. Patients were treated with surgery (breast conservation or mastectomy) and chemotherapy (CT) (n=22) or surgery without chemotherapy (n=38). Most patients had radiation therapy (RT). Blood from 22 healthy woman of similar age served as controls. T cell functionality (TCF) was determined following stimulation with plate-bound anti-CD3 (1 µg/ml) and anti-CD28 (0.5 µg/ml) and proliferation was measured by 3H-thymidine uptake. DC functionality (DCF) was determined by ability to present allo-antigens in a mixed lymphocyte reaction. Values for the normal samples determined the normal ranges (NR). Responses were grouped into 4 categories based on their status at 6 months: Group 1 - remained in NR; Group 2 - climbed into NR; Group 3 - remained below NR; Group 4 - fell below NR. Analysis of immunosuppression will be based on lymphocyte subsets, cytokine, COX-2, and PGE2 metabolite levels.T Cell Proliferation AllWith CTNo CT N=60N=22N=38Group 120%14%24%Group 223%23%24%Group 338%41%37%Group 418%23%16% DC Function AllWith CTNo CT N=58N=20N=38Group 143%35%47%Group 219%25%16%Group 317%15%18%Group 421%25%18% Forty-three percent of patients had normal levels (Groups 1 and 2) for TCF and 62% for DCF by 6 months post adjuvant therapy, suggesting that breast cancer patients are potentially amenable to vaccine therapy. 28% of patients had both TCF and DCF in NR; 50% had either TCF or DCF in NR; and 22% had neither in NR. The percentage of patients who had TCF in NR by adjuvant therapy was: 35% CT+RT (6/17); 33% CT (1/3); 52% (17/33) RT; and 20% (1/5) neither. The percentage of patients who had DCF in NR by adjuvant therapy was: 67% (10/15) CT+RT; 33% (1/3) CT; 67% (22/33) RT; and 40% (2/5) neither. Proper understanding of the effects of tumor, chemotherapy and radiation therapy on immune function, especially the effects on T cells and DCs, may enable us to identify the appropriate patients in whom to study immunotherapy approaches in women with early breast cancer and to examine strategies to counteract cancer-related defects in immune function. (supported by P50CA116201)

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4131.

Identification of targetable cellular subsets within melanoma tumors

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Background: Human tumors, including melanoma, are complex mixtures of individual, molecularly distinct subpopulations, or clones of cancer cells. Effective cancer therapy will likely require targeting of all tumor subsets within a given cancer. Understanding the tumor complexity and the ability to identify points of therapeutic vulnerability within the individual tumor subsets will be essential for development of effective personalized cancer therapies. Methods: We have developed an approach that combines identification of individual tumor subsets using a multiparameter nuclear flow cytometry coupled with a high-resolution genomic analysis using the array-based comparative genomic hybridization (aCGH). Melanoma nuclei were isolated from tumor tissues and subjected to flow cytomery using melanocyte-specific antibodies (to separate melanoma cells from stroma) and DNA content, to separate individual tumor subpopulations. DNA extracted from isolated nuclear subpopulations was extracted and analyzed by aCGH. This approach was adopted for both fresh-frozen and paraffin-embedded clinical specimens. Results: We initially demonstrate the feasibility of the outlined approach by successful separation of melanoma from stromal nuclei and separation of individual melanoma nuclear subpopulations by DNA content. aCGH analysis of the DNA derived from isolated tumor subpopulations allowed successful identification of potentially targetable molecular aberrations in individual subsets of tumor cells. Notably, such aberrations were often not detected in unsorted, bulk tumors analyzed by the same high-resolution aCGH approach. Conclusions: We demonstrate a feasible approach to in-depth molecular analysis of tumor subpopulations within a clinical cancer tissue. This approach allows identification of potentially targetable molecular aberrations within individual tumor subsets, thus opening a possibility for a broad tumor targeting through design of individually-tailored therapeutic approaches.

No significant financial relationships to disclose.

Granulocyte macrophage colony stimulating factor as adjuvant therapy for resected stage III/IV melanoma: Retrospective review of a single institutional experience

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Background: Preliminary data suggesting positive clinical outcome in patients treated with adjuvant granulocyte macrophage colony stimulating factor (GM-CSF) following surgical resection of stage III/IV melanoma already exist (Spitler et al). A compassionate use protocol for the treatment of such patients with the “Spitler” regimen (GM-CSF administered at 250 mcg/day s.c. for 14 days of a 28 day cycle) has been ongoing at Mayo Clinic. Herein we present a retrospective review. Methods: Between 1998 and 2006, data was collected from 30 patients rendered disease free by surgery who received adjuvant GM-CSF. GM-CSF was administered per the “Spitler” regimen, although one patient received a reduced dose of 125mcg/day. The Kaplan-Meier approach was used to estimate relapse free survival. Results: Thirty patients (14 Female) with a median age of 53 and excellent performance status were evaluated. Most patients had resected stage III melanoma (Stage II/III/IV: 1/20/9). Median followup was 33 months (3–96). Twenty one patients were treated with GM-CSF for at least 12 months. Overall, relapse-free survival at 1 year was estimated to be 69% (95% confidence interval (CI) of 54% to 88%), reducing to 44% (95% CI of 29% to 67%) at 3 years. According to stage, relapse free survival at 1 year was 70% (III) and 63% (IV), and at 3 years was 54% (III), and 13% (IV). Among the 21 patients completing at least 1 year of therapy, relapse free survival at 3 years was 52%. Seventeen patients relapsed (III/IV: 10/7). Six of these patients were retreated and only two relapsed. Toxicities were grade 1 with most common being injection site rash (23%), asthenia (17%), myalgia (17%), and fever (7%). One patient required dose modification for elevated liver function tests. Conclusions: Although limited in scope, our data further support a potential beneficial effect of adjuvant GM-CSF in resected stage III/IV melanoma. Recurrences in the treated population were often localized and amenable to further surgical treatment. The clinical relevance of this strategy is currently being prospectively tested (E4697, now closed to accrual).

No significant financial relationships to disclose.