Characterizing the detection threshold for optical imaging in surgical oncology.

BACKGROUND AND OBJECTIVES: Optical imaging to guide cancer resections is rapidly transitioning into the operating room. However, the sensitivity of this technique to detect subclinical disease is yet characterized. The purpose of this study was to determine the minimum range of cancer cells that can be detected by antibody-based fluorescence imaging. METHODS: 2LMP (breast), COLO-205 (colon), MiaPaca-2 (pancreas), and SCC-1 (head and neck) cells incubated in vitro with cetuximab-IRDye800CW (dose range 8.6-86 nM) were implanted subcutaneously in mice (n = 3 mice, 5 tumors/mouse). Following incubation with 8.6 × 10-2 µM of cetuximab-IRDye800CW in vitro, serial dilutions of each cell type (1 × 103 -1 × 106 ) were implanted subcutaneously (n = 3, 5 tumors/mouse). Tumors were imaged with Pearl Impulse and Xenogen IVIS 100 imaging systems. Scatchard analysis was performed to determine receptor density and kinetics for each cell line. RESULTS: Under conditions of minimal cetuximab-IRDye800CW exposure to low cellular quantity, closed-field fluorescence imaging theoretically detected a minimum of 4.2 × 104 -9.5 × 104 2LMP cells, 1.9 × 105 -4.5 × 105 MiaPaca-2 cells, and 2.4 × 104 -6.7 × 104 SCC-1 cells; COLO-205 cells could not be identified. Higher EGFR-mediated uptake of cetuximab correlated with sensitivity of detection. CONCLUSION: This study supports the clinical utility of cetuximab-IRDye800CW to sensitively localize subclinical disease in the surgical setting.

Dynamic contrast-enhanced MRI evaluates the early response of human head and neck tumor xenografts following anti-EMMPRIN therapy with cisplatin or irradiation.

PURPOSE: To assess the early therapeutic effects of anti-EMMPRIN (extracellular matrix metalloprotease inducer) antibody with/without cisplatin or X-ray radiation in head and neck cancer mouse models using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). MATERIALS AND METHODS: Mice bearing SCC1 (or OSC19) tumor xenografts were treated with anti-EMMPRIN antibody, radiation, cisplatin, or anti-EMMPRIN antibody plus cisplatin (or radiation) for a week (n = 4-5 per group). DCE-MRI was carried out on a 9.4T small animal MR scanner on days 0, 3, and 7, and K(trans) values were averaged in a 0.5-mm-thick peripheral tumor region. Ki67 and CD31 staining were implemented for all tumors after imaging. RESULTS: The K(trans) changes of SCC1 and OSC19 tumors treated with anti-EMMPRIN antibody for 3 days were -18 ± 8% and 4 ± 7%, respectively, which were significantly lower than those of control groups (39 ± 5% and 45 ± 7%; P = 0.0025 and 0.0220, respectively). When cisplatin was added, those were -42 ± 9% and -44 ± 9%, respectively, and with radiation, -45 ± 9% and -27 ± 10%, respectively, which were also significantly lower than those of control groups (P < 0.0001 for all four comparisons). In the eight groups untreated (served as control) or treated with anti-EMMPRIN antibody with/without cisplatin or radiation, the mean K(trans) change for 3 days was significantly correlated with the mean tumor volume change for 7 days (r = 0.74, P = 0.0346), Ki67-expressing cell density (r = 0.96, P = 0.0001), and CD31 density (r = 0.84, P = 0.0084). CONCLUSION: DCE-MRI might be utilized to assess the early therapeutic effects of anti-EMMPRIN antibody with/without chemotherapy or radiotherapy in head and neck cancer.

Laparoscopic Fluorescent Visualization of the Ureter With Intravenous IRDye800CW.

OBJECTIVES: Ureter injury is a serious complication of laparoscopic surgery. Current strategies to identify the ureters, such as placement of a ureteral stent, carry additional risks for patients. We hypothesize that the systemically injected near-infrared (NIR) dye IRDye800CW-CA can be used to visualize ureters intraoperatively. METHODS: Adult female mixed-breed pigs weighing 24 to 41 kg (n = 2 per dose) were given a 30, 60, or 120 µg/kg systemic injection of IRDye800CW-CA. Using the Food and Drug Administration-cleared Pinpoint laparoscopic NIR system, images of the ureter and bladder were captured every 10 minutes for 60 minutes after injection. To determine the biodistribution of the dye, tissues were collected for ex vivo analysis with the Pearl Impulse system. ImageJ software was used to quantify fluorescence signal and signal-to-background ratio (SBR) for the intraoperative images. RESULTS: The ureter was identified in all pigs at each dose, with peak intensity reached by 30 minutes and remaining elevated throughout the duration of imaging (60 minutes). The 60 µg/kg dose was determined to be optimal for differentiating ureters according to absolute fluorescence (>60 counts/pixel) and SBR (3.1). Urine fluorescence was inversely related to plasma fluorescence (R(2) = -0.82). Ex vivo imaging of kidney, ureter, bladder, and abdominal wall tissues revealed low fluorescence. CONCLUSION: Systemic administration of IRDye800CW-CA shows promise in providing ureteral identification with high specificity during laparoscopic surgery. The low dose required, rapid time to visualization, and absence of invasive ureteral instrumentation inherent to this technique may reduce complications related to pelvic surgery.

Fluorescence-guided resection of experimental malignant glioma using cetuximab-IRDye 800CW.

The standard treatment for glioblastoma multiforme (GBM) remains maximal safe surgical resection. Here, we evaluated the ability of a systemically administered antibody-dye probe conjugate (cetuximab-IRDye 800CW) to provide sufficient fluorescent contrast for surgical resection of disease in both subcutaneous and orthotopic animal models of GBM. Multiple luciferase-positive GBM cell lines (D-54MG, U-87MG, and U-251MG; n = 5) were implanted in mouse flank and tumors were fluorescently imaged daily using a closed-field near-infrared (NIR) system after cetuximab-IRDye 800CW systemic administration. Orthotopic models were also generated (n = 5), and tumor resection was performed under white light and fluorescence guidance using an FDA-approved wide-field NIR imaging system. Residual tumor was monitored using luciferase imaging. Immunohistochemistry was performed to characterize tumor fluorescence, epidermal growth factor receptor (EGFR) expression, and vessel density. Daily imaging of tumors revealed an average tumor-to-background (TBR) of 4.5 for U-87MG, 4.1 for D-54MG, and 3.7 for U-251MG. Fluorescence intensity within the tumors peaked on day-1 after cetuximab-IRDye 800CW administration, however the TBR increased over time in two of the three cell lines. For the orthotopic model, TBR on surgery day ranged from 19 to 23 during wide-field, intraoperative imaging. Surgical resection under white light on day 3 after cetuximab-IRDye 800CW resulted in an average 41% reduction in luciferase signal while fluorescence-guided resection using wide-field NIR imaging resulted in a significantly (P = 0.001) greater reduction in luciferase signal (87%). Reduction of luciferase signal was found to correlate (R (2) = 0.99) with reduction in fluorescence intensity. Fluorescence intensity was found to correlate (P < 0.05) with EGFR expression in D-54MG and U-251MG tumor types but not U-87MG. However, tumor fluorescence was found to correlate with vessel density for the U-87MG tumors. Here we show systemic administration of cetuximab-IRDye 800CW in combination with wide-field NIR imaging provided robust and specific fluorescence contrast for successful localization of disease in subcutaneous and orthotopic animal models of GBM.

Breast cancer imaging using the near-infrared fluorescent agent, CLR1502.

Positive margins after breast conservation surgery represent a significant problem in the treatment of breast cancer. The near-infrared fluorescence agent CLR1502 (Cellectar Biosciences, Madison, WI) was studied in a preclinical breast cancer model to determine imaging properties and ability to detect small islands of malignancy. Nude mice bearing human breast cancer flank xenografts were given a systemic injection of CLR1502, and imaging was performed using LUNA (Novadaq Technologies Inc., Richmond, BC) and Pearl Impulse (LI-COR Biosciences, Lincoln, NE) devices. Normal tissues were examined for fluorescence signal, and conventional and fluorescence histology was performed using the Odyssey scanner. Peak tumor to background ratio occurred 2 days after injection with CLR1502. The smallest amount of tumor that was imaged and detected using these devices was 1.9 mg, equivalent to 1.9 × 106 cells. The highest fluorescence signal was seen in tumor and normal lymph node tissue, and the lowest fluorescence signal was seen in muscle and plasma. Human breast cancer tumors can be imaged in vivo with multiple optical imaging platforms using CLR1502. This pilot study supports further investigations of this fluorescent agent for improving surgical resection of malignancies, with the goal of eventual clinical translation.

Use of monoclonal antibody-IRDye800CW bioconjugates in the resection of breast cancer.

BACKGROUND: Complete surgical resection of breast cancer is a powerful determinant of patient outcome, and failure to achieve negative margins results in reoperation in between 30% and 60% of patients. We hypothesize that repurposing Food and Drug Administration-approved antibodies as tumor-targeting diagnostic molecules can function as optical contrast agents to identify the boundaries of malignant tissue intraoperatively. MATERIALS AND METHODS: The monoclonal antibodies bevacizumab, cetuximab, panitumumab, trastuzumab, and tocilizumab were covalently linked to a near-infrared fluorescence probe (IRDye800CW) and in vitro binding assays were performed to confirm ligand-specific binding. Nude mice bearing human breast cancer flank tumors were intravenously injected with the antibody-IRDye800 bioconjugates and imaged over time. Tumor resections were performed using the SPY and Pearl Impulse systems, and the presence or absence of tumor was confirmed by conventional and fluorescence histology. RESULTS: Tumor was distinguishable from normal tissue using both SPY and Pearl systems, with both platforms being able to detect tumor as small as 0.5 mg. Serial surgical resections demonstrated that real-time fluorescence can differentiate subclinical segments of disease. Pathologic examination of samples by conventional and optical histology using the Odyssey scanner confirmed that the bioconjugates were specific for tumor cells and allowed accurate differentiation of malignant areas from normal tissue. CONCLUSIONS: Human breast cancer tumors can be imaged in vivo with multiple optical imaging platforms using near-infrared fluorescently labeled antibodies. These data support additional preclinical investigations for improving the surgical resection of malignancies with the goal of eventual clinical translation.

Characterizing the Utility and Limitations of Repurposing an Open-Field Optical Imaging Device for Fluorescence-Guided Surgery in Head and Neck Cancer Patients.

The purpose of this study was to assess the potential of U.S. Food and Drug Administration-cleared devices designed for indocyanine green-based perfusion imaging to identify cancer-specific bioconjugates with overlapping excitation and emission wavelengths. Recent clinical trials have demonstrated potential for fluorescence-guided surgery, but the time and cost of the approval process may impede clinical translation. To expedite this translation, we explored the feasibility of repurposing existing optical imaging devices for fluorescence-guided surgery. METHODS: Consenting patients (n = 15) scheduled for curative resection were enrolled in a clinical trial evaluating the safety and specificity of cetuximab-IRDye800 (NCT01987375). Open-field fluorescence imaging was performed preoperatively and during the surgical resection. Fluorescence intensity was quantified using integrated instrument software, and the tumor-to-background ratio characterized fluorescence contrast. RESULTS: In the preoperative clinic, the open-field device demonstrated potential to guide preoperative mapping of tumor borders, optimize the day of surgery, and identify occult lesions. Intraoperatively, the device demonstrated robust potential to guide surgical resections, as all peak tumor-to-background ratios were greater than 2 (range, 2.2-14.1). Postresection wound bed fluorescence was significantly less than preresection tumor fluorescence (P < 0.001). The repurposed device also successfully identified positive margins. CONCLUSION: The open-field imaging device was successfully repurposed to distinguish cancer from normal tissue in the preoperative clinic and throughout surgical resection. This study illuminated the potential for existing open-field optical imaging devices with overlapping excitation and emission spectra to be used for fluorescence-guided surgery.

Understanding the Value of Both Laparoscopic and Robotic Approaches Compared to the Open Approach in Colorectal Surgery.

INTRO: Although the use of laparoscopy has significantly increased in colorectal procedures, robotic surgery may enable additional cases to be performed using a minimally invasive approach. We separately evaluated the value of laparoscopic and robotic colorectal procedures compared to the open approach. METHODS: Patients undergoing nonemergent colorectal operations from 2010 to 2013 with National Surgical Quality Improvement Project data were identified. Robotic and laparoscopic procedures were separately matched (1:1) to open cases. Outcomes included 30-day composite morbidity, length of stay, operative time, and inpatient costs. Frequently used intraoperative disposable items were categorized, and significant cost contributors were identified by surgical approach. Statistical differences were determined with Chi-square and Wilcoxon signed-rank tests. RESULTS: Both laparoscopic (n = 67) and robotic (n = 45) approaches were associated with decreased composite morbidity compared to matched open cases (lap vs. open: 22.4% vs. 49.2%, P < .01; robotic vs. open: 6.7% vs. 33.3%, P < .01). Median length of stay was significantly shorter for both laparoscopic and robotic compared to open surgery (lap vs. open: 5 vs. 7 days, P < .01; robotic vs. open: 5 vs. 7 days, P < .01). Median hospital costs were similar between laparoscopic and open surgery ($13,319 vs. $14,039; P = .80) and robotic and open surgery ($13,778 vs. $13,629; P = .48). CONCLUSION: These findings illustrate the value for both laparoscopic and robotic approaches to colorectal surgery compared to the open approach in terms of short-term outcomes and inpatient costs. Advanced intraoperative disposable items such as cutting staplers and energy devices are important targets for additional cost containment.

Photoimmunotherapy of residual disease after incomplete surgical resection in head and neck cancer models.

Antibody-based photodynamic therapy, or photoimmunotherapy (PIT), is a novel, targeted cancer therapy, which can serve as both a diagnostic and a therapeutic agent. The primary objective of this study was to evaluate the capacity of panitumumab-IRDye700DX (Pan-IR700) to eliminate microscopic tumor remnants in the postsurgical setting, which was accomplished using novel in vitro and in vivo models of residual disease after incomplete resection. Additionally, PIT was evaluated in fresh human-derived cancer tissue. To determine a threshold for cellular regrowth after PIT, an in vitro assay was performed using a range of cells representing microscopic disease quantities. Long-term growth inhibition was induced after treatment of 5 × 10(3) and 1 × 10(4) cells at 6 J. A novel in vivo mouse model of subtotal tumor resection was used to assess the effectiveness of Pan-IR700 mediated PIT to eliminate residual disease and inhibit recurrence in the post-surgical wound bed. Mice receiving surgical treatment plus adjuvant PIT showed a threefold and fourfold reduction in tumor regrowth at 30 days post PIT in the 50% and 90% subtotal resection groups, respectively (as measured by bioluminescence imaging), demonstrating a significant (P < 0.001) reduction in tumor regrowth. To determine the translatability of epidermal growth factor receptor (EGFR)-targeted PIT, SCCHN human tissues (n = 12) were treated with Pan-IR700. A significant reduction (P < 0.001) in ATP levels was observed after treatment with Pan-IR700 and 100 J cm(-2) (48% ± 5%) and 150 J cm(-2) (49% ± 7%) when compared to baseline. Targeting EGFR with Pan-IR700 has robust potential to provide a tumor-specific mechanism for eliminating residual disease in the surgical setting, thereby increasing therapeutic efficacy, prolonging progression-free survival, and decreasing morbidity.

IND-directed safety and biodistribution study of intravenously injected cetuximab-IRDye800 in cynomolgus macaques.

PURPOSE: The use of receptor-targeted antibodies conjugated to fluorophores is actively being explored for real-time imaging of disease states; however, the toxicity of the bioconjugate has not been assessed in non-human primates. PROCEDURES: To this end, the in vivo toxicity and pharmacokinetics of IRDye800 conjugated to cetuximab (cetuximab-IRDye800; 21 mg/kg; equivalent to 250 mg/m(2) human dose) were assessed in male cynomolgus monkeys over 15 days following intravenous injection and compared with an unlabeled cetuximab-dosed control group. RESULTS: Cetuximab-IRDye800 was well tolerated. There were no infusion reactions, adverse clinical signs, mortality, weight loss, or clinical histopathology findings. The plasma half-life for the cetuximab-IRDye800 and cetuximab groups was equivalent (2.5 days). The total recovered cetuximab-IRDye800 in all tissues at study termination was estimated to be 12 % of the total dose. Both cetuximab-IRDye800 and cetuximab groups showed increased QTc after dosing. The QTc for the cetuximab-dosed group returned to baseline by day 15, while the QTc of the cetuximab-IRDye800 remained elevated compared to baseline. CONCLUSION: IRDye800 in low molar ratios does not significantly impact cetuximab half-life or result in organ toxicity. These studies support careful cardiac monitoring (ECG) for human studies using fluorescent dyes.

In Vivo Fluorescence Immunohistochemistry: Localization of Fluorescently Labeled Cetuximab in Squamous Cell Carcinomas.

Anti-EGFR (epidermal growth factor receptor) antibody based treatment strategies have been successfully implemented in head and neck squamous cell carcinoma (HNSCC). Unfortunately, predicting an accurate and reliable therapeutic response remains a challenge on a per-patient basis. Although significant efforts have been invested in understanding EGFR-mediated changes in cell signaling related to treatment efficacy, the delivery and histological localization in (peri-)tumoral compartments of antibody-based therapeutics in human tumors is poorly understood nor ever made visible. In this first in-human study of a systemically administered near-infrared (NIR) fluorescently labeled therapeutic antibody, cetuximab-IRDye800CW (2.5 mg/m(2), 25 mg/m(2), and 62.5 mg/m(2)), we show that by optical molecular imaging (i.e. denominated as In vivo Fluorescence Immunohistochemistry) we were able to evaluate localization of fluorescently labeled cetuximab. Clearly, optical molecular imaging with fluorescently labeled antibodies correlating morphological (peri-)tumoral characteristics to levels of antibody delivery, may improve treatment paradigms based on understanding true tumoral antibody delivery.

Safety and Tumor Specificity of Cetuximab-IRDye800 for Surgical Navigation in Head and Neck Cancer.

PURPOSE: Positive margins dominate clinical outcomes after surgical resections in most solid cancer types, including head and neck squamous cell carcinoma. Unfortunately, surgeons remove cancer in the same manner they have for a century with complete dependence on subjective tissue changes to identify cancer in the operating room. To effect change, we hypothesize that EGFR can be targeted for safe and specific real-time localization of cancer. EXPERIMENTAL DESIGN: A dose escalation study of cetuximab conjugated to IRDye800 was performed in patients (n = 12) undergoing surgical resection of squamous cell carcinoma arising in the head and neck. Safety and pharmacokinetic data were obtained out to 30 days after infusion. Multi-instrument fluorescence imaging was performed in the operating room and in surgical pathology. RESULTS: There were no grade 2 or higher adverse events attributable to cetuximab-IRDye800. Fluorescence imaging with an intraoperative, wide-field device successfully differentiated tumor from normal tissue during resection with an average tumor-to-background ratio of 5.2 in the highest dose range. Optical imaging identified opportunity for more precise identification of tumor during the surgical procedure and during the pathologic analysis of tissues ex vivo. Fluorescence levels positively correlated with EGFR levels. CONCLUSIONS: We demonstrate for the first time that commercially available antibodies can be fluorescently labeled and safely administered to humans to identify cancer with sub-millimeter resolution, which has the potential to improve outcomes in clinical oncology.

Ultrasound-stimulated drug delivery for treatment of residual disease after incomplete resection of head and neck cancer.

Microbubbles triggered with localized ultrasound (US) can improve tumor drug delivery and retention. Termed US-stimulated drug delivery, this strategy was applied to head and neck cancer (HNC) in a post-surgical tumor resection model. Luciferase-positive HNC squamous cell carcinoma (SCC) was implanted in the flanks of nude athymic mice (N = 24) that underwent various degrees of surgical tumor resection (0%, 50% or 100%). After surgery, animals received adjuvant therapy with cetuximab-IRDye alone, or cetuximab-IRDye in combination with US-stimulated drug delivery or saline injections (control) on days 4, 7 and 10. Tumor drug delivery was assessed on days 0, 4, 7, 10, 14 and 17 with an in vivo fluorescence imaging system, and tumor viability was evaluated at the same times with in vivo bioluminescence imaging. Tumor caliper measurements occurred two times per week for 24 d. Optical imaging revealed that in the 50% tumor resection group, US-stimulated drug delivery resulted in a significant increase in cetuximab delivery compared with administration of drug alone on day 10 (day of peak fluorescence) (p = 0.03). Tumor viability decreased in all groups that received cetuximab-IRDye in combination with US-stimulated drug delivery, compared with the group that received only the drug. After various degrees of surgical resection, this novel study reports positive improvements in drug uptake in the residual cancer cells when drug delivery is stimulated with US.