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U.S. Pharmacopeia (USP) general chapter825, "Radiopharmaceuticals: Preparation, Compounding, Dispensing, and Repackaging," is a new standard proposed to provide minimum requirements for the preparation, compounding, dispensing, and repackaging of sterile and nonsterile radiopharmaceuticals. This new standard represents endeavors on the part of the USP to respond to appeals by nuclear medicine professionals to move beyond a minimal supplement to USP797and provide policies specific to radiopharmaceuticals. USP825provides nuclear pharmacies and nuclear medicine departments in hospitals and clinics with the benchmarks to assess current practice activities and integrate needed changes to meet regulatory and accreditation audit reviews. This continuing education article focuses on components of USP825specific to the nuclear medicine technologist for a better understanding of obligations when preparing sterile radiopharmaceuticals for clinical use.

To determine the anatomic characteristics and pharmacokinetic properties of intravitreally placed bevacizumab and ranibizumab after pars plana lensectomy or pars plana vitrectomy and to compare these with nonoperated control eyes in a rabbit model.Three groups of six Dutch-belted rabbits each underwent pars plana vitrectomy, pars plana lensectomy, or served as nonsurgical controls. Twelve days after surgery, 3 rabbits from each group underwent intravitreal injection in one eye with 1.25 mg/0.05 mL I-124-bevacizumab or 0.5 mg/0.05 mL I-124-ranibizumab. Serial imaging with integrated positron emission and computed tomography (PET/CT) were obtained on Days 0, 2, 5, 7, 14, 21, 28, and 35. Measured radioactivity emission in becquerels/milliliter was used to calculate the half-lives for each agent.The intravitreally placed radiolabeled agents were contained within the vitreous cavity for the duration of the study. The average clearance half-lives with standard error for bevacizumab and ranibizumab after correction for radioactive decay were, respectively, 4.22 ± 0.07 days and 2.81 ± 0.05 days in unoperated eyes, 2.30 ± 0.09 days (P0.0001) and 2.13 ± 0.05 days (P0.0001) after vitrectomy, and 2.08 ± 0.07 days (P = 0.0001) and 1.79 ± 0.05 days (P0.0001) after lensectomy.Intravitreal retention was longer for bevacizumab than ranibizumab within all study groups and was significantly reduced after vitrectomy and lensectomy for both agents. Consideration for more frequent intravitreal anti-vascular endothelial growth factor dosing regimens may be made for patients whose treated eyes have undergone previous vitrectomy or who are aphakic.

A blind performance test was conducted to evaluate dose-calibrator measurements at nuclear pharmacies in the United States (US). Two test-sample geometries were chosen to represent those used for measurements of 90Y-ibritumomab tiuxetan (ZEVALIN). The radioactivity concentration of test-samples was verified by the US National Institute of Standards and Technology. Forty-five results were reported by 10 participants. Eighty percent of reported values were within the US Pharmacopoeia content standard (+/-10%) for 90Y-ZEVALIN. All results were within US Nuclear Regulatory Commission conformance limits (+/-20%) for defining therapeutic misadministrations.

125I-labeled anti-TAG-72 antibodies were applied in radioimmunoguided surgery (RIGS) to remove gross and occult tumors. It is challenging to handle 125I-labeled materials. PET/CT image-guided surgery utilizes 18FDG to monitor the biochemical activity of the tumor and to integrate pre- and postoperative imaging for complete tumor removal. PET/CT image-guided surgery only detects later stage disease. Fluorescence image-guided surgery using anti-TAG-72 antibodies may provide opportunities for intraoperative cancer detection of both gross and occult tumors. J. Surg. Oncol. 2007;96:297–308. © 2007 Wiley-Liss, Inc.

The Na+/I- symporter (NIS) is a membrane glycoprotein that facilitates the uptake of iodine into thyroid follicular cells. Recently, we and others have demonstrated the feasibility of imaging subcutaneous xenografts expressing exogenous NIS, suggesting that NIS may serve as an imaging reporter gene to monitor vector delivery and therapeutic gene expression. In this study, we established NIS-expressing pulmonary tumors in nude mice to investigate the minimal tumor size required for in vivo detection of pulmonary tumors by single photon emission computed tomography (SPECT) with pinhole collimation. In order to define the anatomic location of NIS-expressing tumor nodules detectable by SPECT, we performed simultaneous, dual-isotope imaging. We injected 1 mCi 99mTc-MAA via tail vein to image pulmonary perfusion and injected 1 mCi Na125I intraperitoneally to image NIS-expressing tumors. Fused images showed that 99mTc-MAA perfusion defects correlated with NIS-mediated 125I uptake. Post-mortem analysis revealed that tumors 3 mm in diameter could be detected by SPECT with pinhole collimation. These studies demonstrate the feasibility of SPECT to detect pulmonary tumors expressing exogenous NIS in mice.

Radioactive iodide uptake (RAIU) in thyroid follicular epithelial cells, mediated by the sodium iodide symporter (NIS), is the first rate-limiting step in iodide accumulation which provides a mechanism for effective radioiodide treatment for patients with thyroid cancer. We hypothesize that NIS gene transfer to non-thyroid tumor cells will enhance intracellular radioiodide accumulation and result in better tumor control. Here, we performed non-invasive tumor imaging and (131)I therapy studies using rats bearing intracerebral F98 gliomas that have been retrovirally transduced with human NIS. Our results show that: (1) NIS is expressed in the intracerebral F98/NIS gliomas; (2) F98/NIS gliomas can be imaged by (99m)TcO(4) (whose uptake is also mediated by NIS) and (123)I scintigraphy; (3) significant amounts of radioiodide were retained in the tumors at 24 h after (123)I injection; (4) RAIU and NIS expression in the thyroid gland can be reduced by feeding a thyroxine-supplemented diet; and (5) survival time was increased in rats bearing F98/hNIS tumors by (131)I treatment. These studies warrant further investigating tumor imaging and therapeutic strategies based on NIS gene transfer followed by radioiodide administration in a variety of human cancers.

A radioactively labeled blue liposome formulation was developed for use in presurgical lymphoscintigraphy and intraoperative sentinel node localization to avoid the differing injection site clearance kinetics of the conjunctive use of separate formulations of low molecular weight blue dye and radioactively labeled macromolecular sulfur colloid. Blue liposomes containing glutathione in the internal aqueous phase were prepared from blue dyed lipids obtained by covalently binding Reactive Blue II to phosphatidylethanolamine (PE) fractions of phospholipid extracts. Four phospholipid extracts with differing PE fractions and a centrifugation technique were evaluated with the goal of maximizing the blue color intensity of the formulation. Stability of the formulations was evaluated by studying radiolabeling efficiency (using a membrane permeable lipophilic carrier of the commonly used diagnostic radionuclide, technetium-99m) and particle-size distribution over 30-60-day periods. Blue color was not altered by varying the PE content, while centrifugation was an effective and convenient method to maximize the blue color intensity of the final preparation. The particle size distribution of the prepared liposomes ranged from 200-300 nm (considered ideal for lymphoscintigraphy studies) and did not change significantly, while radiolabeling efficiency exceeded 80% for up to 1 month. The described kit formulation for the preparation of radiolabeled blue liposomes is suitable for commercial production allowing widespread clinical use. The combination of a means of visual identification and tracking of the liposomes through the lymphatic channels along with the ability to trace the preparation using standard radiation detection instrumentation provides the surgeon with an improved radiolabeled compound for lymphoscintigraphy and intraoperative sentinel lymph node identification.

BACKGROUND The sodium iodide symporter (NIS) mediates iodide uptake in thyroid follicular cells and provides a mechanism for effective radioiodide treatment of residual, recurrent, and metastatic thyroid cancers. This study investigated the clinical applications of NIS gene transfer for prostate cancer using the MATLyLu metastatic rat model. METHODS MATLyLu cells expressing NIS were injected subcutaneously in Copenhagen rats, which developed metastases in lymph nodes and lungs. NIS protein expression was evaluated by Western blot and immunohistochemistry, and function was measured by tissue gamma counts and whole-body imaging following radionuclide administration. RESULTS In vitro radioiodide-concentrating activity was increased up to 72-fold in a mixed population of MATLyLu-hNIS cells. NIS protein expression was confirmed in subcutaneous MATLyLu-hNIS tumors by immunohistochemistry and Western blot. Gamma counts of subcutaneous MATLyLu-hNIS tumors were 23-fold higher than parental MATLyLu tumors and radionuclide uptake in subcutaneous MATLyLu-hNIS tumors and lymph node metastases was visualized by whole-body image analysis. CONCLUSIONS NIS expression by a proportion of cells in a population was sufficient to confer radionuclide-concentrating function in subcutaneous and metastatic MATLyLu tumors. Ablation of residual normal and neoplastic prostate tissues by radioiodide after prostate-restricted NIS gene transfer might be a novel adjuvant therapy to prostatectomy for the treatment of advanced prostate cancer. Prostate 50: 170–178, 2002. © 2002 Wiley-Liss, Inc.

Glomerular disease is the most common cause of kidney failure in the United States. Gene therapy represents a novel approach to the treatment of diseases of the glomerulus, but necessitates safe and accurate tissue targeting, combined with efficient gene transfer into the cells of interest. Our previous work demonstrated effective glomerular gene transfer after arterial injection of replication deficient recombinant adenovirus complexed to 16 μm polystyrene microspheres. The insoluble nature of polystyrene makes glomerular ischemia a potential complication of the procedure. On this basis, we postulated that biodegradable gelatin particles could serve as transport vehicles in this system. To address this question, we assessed the in vivo degradation of Tc-99m labeled gelatin or polystyrene particles in the kidney following selective renal artery injection. Radioactivity declined 2–3 fold faster in a gelatin-injected pig kidney, when compared to polystyrene injected animals. The discrepancy in signal loss between gelatin and polystyrene injected animals could not be explained by differences in the rate of dissociation of Tc-99m from each particle type, and suggest that gelatin particles degrade once lodged in the glomerular capillary. These data suggest that biodegradable gelatin particles may help to minimize ischemic potential when used to shuttle therapeutic DNA to the glomerulus.

Objectives. No standard noninvasive diagnostic test reliably differentiates patients with organ-confined prostate cancer from those with lymph node metastases. The ability of a radiolabeled monoclonal antibody, indium-111 ( 111 In)-capromab pendetide, to identify sites of metastatic disease in patients at moderate to high risk of nodal involvement was investigated. Methods. The study prospectively evaluated 160 patients with prostate cancer scheduled to undergo pelvic lymph node dissection (PLND) before or during definitive treatment. All were at relatively high risk of nodal involvement by virtue of significantly elevated baseline prostate-specific antigen (PSA) values, Gleason scores, and/or locally advanced clinical stages of disease. The histologic findings of the PLNDs were compared with the results of immunoscintigraphy, computed tomography, and magnetic resonance imaging. Results. Among the 152 evaluable patients studied with 111 In-capromab pendetide before PLND, the sensitivity of immunoscintigraphy for lymph node detection was 62% and the specificity was 72%; the positive predictive value was 62% and the negative predictive value was 72%. In comparison, the sensitivity of computed tomography and magnetic resonance imaging was 4% and 15%, respectively, and the specificity was 100% for both procedures on the basis of a large number of negative interpretations. Logistic regression analysis revealed that immunoscintigraphy with 111 In-capromab pendetide provided strong, independent evidence of the presence of lymph node metastases. Furthermore, the analysis indicated that certain combinations of PSA, Gleason score, and 111 In-capromab pendetide were particularly effective at predicting the risk of nodal involvement. Conclusions. Immunoscintigraphy with 111 In-capromab pendetide outperformed standard diagnostic imaging techniques in the detection of prostate cancer lymph node metastases and provided independent prognostic information that complemented PSA, Gleason score, and clinical stage.

Purpose. The stability of iobenguane sulfate stored at 4–7 °C over 91 days was studied. Methods. An iobenguane sulfate solution at a concentration of 2.2 mg/mL was prepared in a top-fill i.v. bag using 143 mg of iobenguane sulfate and 65 mL of Sterile Water for Injection, USP. The solution was poured through a 0.22- μm filter assembly for sterilization into 60 1-mL polycarbonate plastic syringes. Each syringe was filled with 0.9 mL of the iobenguane sulfate solution and stored in amber plastic bags at 4–7 °C. The stability of iobenguane sulfate was analyzed using high-performance liquid chromatography immediately after solution preparation and on days 7, 14, 28, 42, 56, 70, and 91. Samples were inspected for chemical purity by observing for particulate formation and color change. Results. The mean concentration of ioben-guane exceeded 93% of the initial concentration in all samples throughout the 91-day study period. No changes in color or turbidity were observed. Conclusion. Iobenguane sulfate 2.2 mg/mL was stable for 91 days when stored in polycarbonate syringes at 4–7 °C.

Purpose: Sentinel lymph node (SLN) identification using lymphatic mapping is gaining popularity in the management of invasive breast cancer. The purpose of this prospective study was to determine the utility of preoperative lymphoscintigraphy (LS) in patients undergoing intraoperative lymphatic mapping (ILM). Methods: On the day of surgery, patients were injected with 400 μCi Tc-99m sulfur colloid (filtered) around the tumor or the biopsy cavity (100 μCi in each quadrant). The patients undergoing needle localization biopsy received a single injection of 400 μCi. Imaging was performed for 30 minutes and after 2 hours following the injection to trace the movement of radionuclide. A biplanar imaging technique was utilized for the localization of the sentinel node. The patients were then taken to the operating room, where ILM was performed utilizing a hand-held gamma detector probe (GDP) and isosulfan blue dye (IBD). Any sentinel nodes were identified and removed; subsequently, a standard axillary node dissection was performed. Results: One male and 24 female patients (n = 25) enrolled in and completed the study. Primary breast tumor sites were in the following quadrants: upper outer (15), lower outer (2), upper inner (3), lower inner (2), and central (3). A SLN was identified by ILM in 23 25 (92%) patients. None of the patients with a histologically negative SLN had axillary metastasis. Preoperative LS identified a suspected sentinel node (SN) in 17 25 (68%) patients. In all 17 of these patients, at least 1 SN was also identified by ILM. Intraoperative findings correlated with the LS (all axillary nodes) in all but one of these patients; ILM located an axillary SN in this patient in whom LS revealed a supraclavicular node. An axillary SLN was identified by ILM in 6 8 patients with negative LS. Furthermore, LS did not identify any drainage to internal mammary nodes, even in 8 patients with medial and central lesions. Conclusions: Although LS has value in identifying the draining lymphatic basin, negative LS does not preclude the identification of a SLN by ILM. LS does not appear to provide additional information to the surgeon performing ILM and, therefore, its routine use in breast cancer patients is not justified. However, its role in identifying internal mammary nodes needs further evaluation.

BACKGROUND Optimum therapy for prostate carcinoma patients requires accurate staging, but computed tomography (CT) and magnetic resonance imaging (MRI) have limitations as methods for detecting soft tissue metastases. In this study, radioimmunoscintigraphy (RIS) was evaluated for its ability to identify sites of metastatic disease in lymph nodes. METHODS RIS was evaluated in 51 prostate carcinoma patients at high risk for metastatic disease. An intravenous infusion of indium-111 capromab pendetide was given, followed by nuclear medicine imaging on two separate dates. Bilateral, open pelvic lymph node dissection was performed with additional exploration and biopsy of scan positive extraprostatic regions. Histologic evaluation of removed tissue confirmed the accuracy of RIS. In addition, results were compared with other standard methods for diagnosing patients prior to surgery. RESULTS Nineteen patients (37%) had evidence of lymph node involvement with RIS. Fifteen of the 19 positive patients had pathologic evidence of cancer in the biopsied lymph nodes. Sensitivity, specificity, accuracy, and the positive predictive value for detection of extraprostatic disease were 75%, 86%, 81%, and 79%, respectively. CT, MRI, and ultrasound of the pelvis demonstrated a combined accuracy of only 48% in detecting lymph node disease. Twenty-five previously undetected sites were deemed positive with RIS. Fourteen of these were biopsy-proven tumor sites, seven were probable tumor sites, and four were assumed to be false-positive. CONCLUSIONS RIS had an impact on patient management through its detection of occult disease in more than 50% of prostate carcinoma patients studied, and it provided information concerning the likelihood that lymph node metastases would be found during surgery. Cancer 1998;83:739-747. © 1998 American Cancer Society.

Iodine-125 radiolabeled monoclonal antibody (MAb) preparations used for radioimmunoguided surgery should be prepared in a manner to insure a stable, efficacious and safe product is used in clinical studies. A number of MAbs have been radioiodinated and used for radioimmunoguided surgery procedures including B72.3 and CC49. Individual MAbs and their fragments differ in their physico-chemical response to conditions of radiolabeling, effects of radiolysis, storage and general handling conditions. A radiolabeling and stability study was completed to evaluate the radiochemical purity and immunoreactivity of NR-LU-10 Fab (nofetumomab) radiolabeled with I-125 at three different specific activities using the IODO-GEN® method. Ratios of 2:1, 1:1, 0.4:1 and 0.2:1(mCi/mg) were used to determine the effects of increasing specific activity on the in vitro stability in a range of potential patient dosages. The radiochemical purity and immunoreactivity of each lot of radiolabeled nofetumomab were determined on days 0, 8, 15, 22, 29 and 36 after radiolabeling using standard tests of instant thin layer chromatography (ITLC), high performance liquid chromatography (HPLC) and whole cell binding assay of immunoreactivity. These standard tests indicated the radiochemical purity on the day of radioiodination was high for all specific activity levels (98–99% for ITLC and >98% for HPLC). Preparations at all specific activities showed a slight decrease in radiochemical purity over time with the amount of unbound I-125 increasing or remaining unchanged. The immunoreactivity net bound showed excellent binding with values ranging from 65–75%. The data indicate I-125 nofetumomab undergoes in vitro physico-chemical changes over time. However, the changes in radio-chemical purity and immunoreactivity were minimal and should prove to be clinically insignificant. © 1998 John Wiley & Sons, Ltd.

The tumor-associated glycoprotein-72 (TAG-72) antigen is highly overexpressed in various human adenocarcinomas and anti-TAG-72 monoclonal antibodies, and fragments are therefore useful as pharmaceutical targeting vectors. In this study, we investigated the effects of site-specific PEGylation with MW 2-4 kDa discrete, branched PEGylation reagents on mCC49 Fab' (MW 50 kDa) via in vitro TAG72 binding, and in vivo blood clearance kinetics, biodistribution, and mouse tumor microPET/CT imaging. mCC49Fab' (Fab'-NEM) was conjugated at a hinge region cysteine with maleimide-dPEG 12-(dPEG24COOH)3 acid (Mal-dPEG-A), maleimide-dPEG12-(dPEG12COOH)3 acid (Mal-dPEG-B), or maleimide-dPEG12-(m-dPEG24)3 (Mal-dPEG-C), and then radiolabeled with iodine-124 ((124)I) in vitro radioligand binding assays and in vivo studies used TAG-72 expressing LS174T human colon carcinoma cells and xenograft mouse tumors. Conjugation of mCC49Fab' with Mal-dPEG-A (Fab'-A) reduced the binding affinity of the non PEGylated Fab' by 30%; however, in vivo, Fab'-A significantly lengthened the blood retention vs Fab'-NEM (47.5 vs 28.1%/ID at 1 h, 25.1 vs 8.4%/ID at 5 h, p < 0.01), showed excellent tumor to background, better microPET/CT images due to higher tumor accumulation, and increased tumor concentration in excised tissues at 72 h by 130% (5.09 ± 0.83 vs 3.83 ± 1.50%ID/g, p < 0.05). Despite the strong similarity of the three PEGylation reagents, PEGylation with Mal-dPEG-B or -C reduced the in vitro binding affinity of Fab'-NEM by 70%, blood retention, microPET/CT imaging tumor signal intensity, and residual 72 h tumor concentration by 49% (3.83 ± 1.50 vs 1.97 ± 0.29%ID/g, p < 0.05) and 63% (3.83 ± 1.50 vs 1.42 ± 0.35%ID/g, p < 0.05), respectively. We conclude that remarkably subtle changes in the structure of the PEGylation reagent can create significantly altered biologic behavior. Further study is warranted of conjugates of the triple branched, negatively charged Mal-dPEG-A.

Purpose To compare the acute thrombogenicity of polyurethane-coated stents with that of bare tantalum stents. Materials and Methods Thirty stents (15 coated with polyurethane) were balloon expanded in 8-mm × 80-cm sections of polytetrafluoroethylene grafts (six stents per graft). Under sterile conditions, 8- and 10-F vascular sheaths were placed percutaneously in the femoral artery and vein of a 100-lb (45-kg) swine. Platelets were labeled with indium-111 and reinjected for quantitative assay. The stented grafts were connected to the arterial and venous sheaths to create an ex vivo fistula. Each fistula was opened for 5,10, 30, 60, or 120 minutes, exposing heparinized blood to fully expanded stents. The fistulas were closed, flushed with saline until clear, and fixed with formalin. Stents were explanted, placed in a radionuclide well counter, and scanned with electron microscopy. Results Quantitatively, there were considerably fewer platelets on coated versus uncoated stents. At 60 minutes, coated stents averaged 12.93 platelets per 1,000 μm 2 compared with 75.88 platelets per 1,000 μm 2 for bare metallic stents. At 120 minutes, there were 23.22 platelets/1,000 μm 2 versus 102.31 platelets/1,000 μm 2 , respectively. Electron microscopy of coated stents demonstrated few scattered platelets at 5,10, and 30 minutes. There was a uniform layer of platelets at 60 and 120 minutes. Uncoated stents demonstrated random areas of platelet clumping at 5,10, and 30 minutes. At 60 and 120 minutes, uncoated stents showed extensive layering of platelets and fibrin. Conclusion Polyurethane coating decreases platelet adhesion, relative to bare tantalum, at all time intervals tested.

PURPOSE. To determine whether bevacizumab and ranibizumab remain confined within the vitreous cavity after intravitreal injection and to determine the pharmacokinetic properties of these agents within the vitreous cavity. METHODS. Radiolabeling with I-124 was completed using a modified Iodogen method. After testing for radiochemical purity, three anesthetized Dutch-belted rabbits underwent intravitreal injection with I-124 bevacizumab, and three underwent it with I-124 ranibizumab. All rabbits were imaged with a Micro PET-CT scanner on days 0, 2, 5, 7, 14, 21, 28, and 35. RESULTS. The intravitreally placed radiolabeled agents were found to be contained within the vitreous cavity for the duration of the study with no extravasation into the central nervous system or elsewhere. I-124 bevacizumab was detectable until day 28, whereas I-124 ranibizumab was detectable until day 21. The kinetic model appears to represent a two-compartment model, and the average retention times for bevacizumab and ranibizumab after correction for radioactive decay were found to be 4.2 days and 2.8 days, respectively. CONCLUSIONS. There was no significant escape of bevacizumab and ranibizumab from the vitreous cavity after intravitreal injection. After correction for radioactive decay, both agents remained detectable until 28 and 21 days, respectively, with retention properties that validated those methods reported in previous studies. (Invest Ophthalmol Vis Sci. 2011;52: 5899‐5903) DOI:10.1167/iovs.10-6862

Tumor-associated glycoprotein-72 (TAG-72) is a mucin-like high-molecular-weight glycosylated protein complex overexpressed by many adenocarcinomas. Antigen-directed cancer surgery using radiolabeled anti-TAG-72 murine monoclonal antibodies (muMAbs) has been previously investigated for colorectal cancer. Survival analysis of primary colorectal cancer patients with a minimum of 15-year follow-up after antigen-directed cancer surgery was performed to assess the impact of complete surgical resection of all detectable radiolabeled anti-TAG-72 muMAb. Survival analysis was performed on 92 patients (study group) with primary colorectal cancer (July 1990 to August 1995) treated with antigen-directed cancer surgery using 125I-labeled anti-TAG-72 muMAb. The study group was subdivided into those with no detectable TAG-72 antigen-bearing tissues (TAG-72 negative, N = 33) and those with persistent detectable TAG-72 antigen-bearing tissues (TAG-72 positive, N = 59) at completion of surgery. Comparisons were made with a control group (546 patients) from the same time period. Study group and control group were demographically similar, as were TAG-72-negative subgroup and TAG-72-positive subgroup. TAG-72-negative subgroup had significantly improved median survival (8.8 versus 2.5 years; P = 0.005) and time-dependent survival (45.4% versus 22.0% at 10 years; P = 0.002 and 39.4% versus 20.3% at 15 years; P = 0.003) compared with TAG-72-positive subgroup. TAG-72 positivity was as an independent predictor of long-term mortality risk, when controlled for pathologic stage of disease. Absence of detectable TAG-72 antigen within the surgical field at completion of antigen-directed cancer surgery for primary colorectal cancer is of significant prognostic value, conferring a long-term survival advantage to those in whom complete surgical removal of all tissues with detectable radiolabeled anti-TAG-72 muMAb was accomplished.

BACKGROUND: The feasibility of using radioimmunoguided surgery (RIGS) (Neoprobe Corp., Columbus, OH) for intraoperative detection of prostate cancer was examined in a pre-Phase I clinical study involving 10 patients having radical prostatectomy and lymphadenectomy. METHODS: Patients were injected with iodine 125-radiolabeled B72.3 monoclonal antibody, which has been shown previously to bind to TAG-72, a pancarcinoma and oncofetal antigen. At a mean of 26 days after injection, RIGS was performed with a specially designed intraoperative gamma-detecting probe. RESULTS: By comparing probe counts with counts of appropriate background tissues, the RIGS system successfully localized tumor to the prostate of all 10 patients. Clinically occult and histologically confirmed bilateral intraprostatic tumor was identified in three patients. One additional patient had bilateral positive intraprostatic probe count ratios with the RIGS technique; on histologic examination, tumor was identified unilaterally, and extensive high-grade prostatic intraepithelial neoplasia was found on the contralateral side. Probe count ratios were positive in the lymph nodes of three patients; two had tumor confirmed histologically. CONCLUSIONS: The current investigation supports the feasibility of the RIGS technique and the need for additional studies.

Accurate assessment of tumor boundaries and recognition of occult disease are important oncologic principles in cancer surgeries. However, existing imaging modalities are not optimized for intraoperative cancer imaging applications. We developed a nanobubble (NB) contrast agent for cancer targeting and dual-mode imaging using optical and ultrasound (US) modalities. The contrast agent was fabricated by encapsulating the Texas Red dye in poly (lactic-co-glycolic acid) (PLGA) NBs and conjugating NBs with cancer-targeting ligands. Both one-step and three-step cancer-targeting strategies were tested on the LS174T human colon cancer cell line. For the one-step process, NBs were conjugated with the humanized HuCC49 Delta C(H)2 antibody to target the over-expressed TAG-72 antigen. For the three-step process, cancer cells were targeted by successive application of the biotinylated HuCC49 Delta C(H)2 antibody, streptavidin, and the biotinylated NBs. Both one-step and three-step processes successfully targeted the cancer cells with high binding affinity. NB-assisted dual-mode imaging was demonstrated on a gelatin phantom that embedded multiple tumor simulators at different NB concentrations. Simultaneous fluorescence and US images were acquired for these tumor simulators and linear correlations were observed between the fluorescence/US intensities and the NB concentrations. Our research demonstrated the technical feasibility of using the dual-mode NB contrast agent for cancer targeting and simultaneous fluorescence/US imaging.

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.

The purpose of the current study was to comprehensively evaluate occupational radiation exposure to all intraoperative and perioperative personnel involved in radioguided surgical procedures utilizing (18)F-fluorodeoxyglucose ((18)F-FDG).Radiation exposure to surgeon, anesthetist, scrub technologist, circulating nurse, preoperative nurse, and postoperative nurse, using aluminum oxide dosimeters read by optically stimulated luminescence technology, was evaluated during ten actual radioguided surgical procedures involving administration of (18)F-FDG.Mean patient dosage of (18)F-FDG was 699 +/- 181 MBq (range 451-984). Mean time from (18)F-FDG injection to initial exposure of personnel to the patient was shortest for the preoperative nurse (75 +/- 63 min, range 0-182) followed by the circulating nurse, anesthetist, scrub technologist, surgeon, and postoperative nurse. Mean total time of exposure of the personnel to the patient was longest for the anesthetist (250 +/- 128 min, range 69-492) followed by the circulating nurse, scrub technologist, surgeon, postoperative nurse, and preoperative nurse. Largest deep dose equivalent per case was received by the surgeon (164 +/- 135 microSv, range 10-580) followed by the anesthetist, scrub technologist, postoperative nurse, circulating nurse, and preoperative nurse. Largest deep dose equivalent per hour of exposure was received by the preoperative nurse (83 +/- 134 microSv/h, range 0-400) followed by the surgeon, anesthetist, postoperative nurse, scrub technologist, and circulating nurse.On a per case basis, occupational radiation exposure to intraoperative and perioperative personnel involved in (18)F-FDG radioguided surgical procedures is relatively small. Development of guidelines for monitoring occupational radiation exposure in (18)F-FDG cases will provide reassurance and afford a safe work environment for such personnel.

Nude mice bearing CX-1 colon tumors were injected with 50 microCi 125I-labeled monoclonal antibody (MAb) B72.3. Radioactivity in tumors was studied with the gamma detecting probe (GDP) on days 1, 3, 7, and 10 after MAb injection. On each day, two mice were sacrificed and sections were examined with autoradiography (ARG), immunoperoxidase methods (IMP), and routine stains. Mean probe counts showed increasing tumor to background ratios and ARG demonstrated a progressive increase in radionuclide in the tumors. The distribution of 125I was primarily around the vascular spaces on day 1, but by day 3 and progressively it appeared in tumor gland lumina and necrotic areas. A regional correlation was shown between radionuclide in vascular spaces and its sequestration in tumor elements.

Monoclonal antibody (MAb) B72.3 IgG was radiolabeled with 131I and administered to female athymic NCr-nu mice bearing the LS-174T human colon adenocarcinoma xenograft to determine if fractionation of MAb dose had any advantage in tumor therapy. In the LS-174T xenograft, only approximately 30%-60% of tumor cells express the B72.3-reactive TAG-72 antigen. The LS-174T xenograft was used to reflect the heterogeneity of the TAG-72 antigen often seen in biopsy specimens from patients. In contrast to a single 600-muCi dose of 131I-B72.3 IgG where 60% of the animals died from toxic effects, two 300-muCi doses of 131I-B72.3 IgG (total of 600 muCi) reduced or eliminated tumor growth in 90% of mice, with only 10% of the animals dying from toxic effects. Dose fractionation even permitted escalation of the dose to three doses (each 1 wk apart) of 300 muCi of 131I-B72.3 IgG (for a total of 900 muCi), resulting in even more extensive tumor reduction or elimination and minimal toxic effects. The use of an isotype-matched control MAb revealed a nonspecific component to tumor growth retardation, but the use of the specific B72.3 IgG demonstrated a much greater therapeutic effect. Tumors that had escaped MAb therapy were analyzed for expression of the B72.3-reactive TAG-72 antigen with the use of the immunoperoxidase method; they were shown to have the same antigenic phenotype as the untreated tumors. We verified tumor elimination by killing the test animals after a 7-week observation period and performing histologic examination of tumor sites. We also monitored toxic effects by histologic examination of numerous organs, including bone marrow. These studies thus demonstrate the advantage of dose fractionation of a radiolabeled MAb for tumor therapy. We anticipate that the concept of dose fractionation can be practically applied in radioimmunotherapeutic clinical trials with the development and use of recombinant-chimeric MAbs and modified constructs.

Each year, approximately 210,000 American men are diagnosed with prostate cancer and 41,800 die from the disease - numbers roughly equal to the incidence and mortality for breast cancer in women. Prostate cancer usually shows no symptoms in early stages, when it is most treatable. To detect the disease early, physicians usually recommend that every man 50 years and older have an annual examination consisting of a digital rectal examination and a prostate specific antigen (PSA) blood test. Conventional treatments such as surgical removal of the diseased prostate, external beam radiation, radioactive seed therapy and hormonal and/or chemotherapy treatment regimens are most successful for early stage prostate cancer and have limited effectiveness in advanced stages of the disease. For this reason, accurate staging of primary and recurrent prostate cancer is mandatory for proper therapeutic decisions. Nuclear medicine imaging of prostate cancer using the radiolabelled monoclonal antibody, (111)In-capromab pendetide, has proven useful in newly diagnosed patients with biopsy-proven prostate cancer in which there is high suspicion of distant metastatic disease and for prostatectomy patients with rising PSA levels and/or suspicion of recurrence or metastatic disease. Although not intended as a screening tool, it is used in conjunction with standard evaluation procedures for improved staging of patients. The monoclonal antibody, designated 7E11-C5, binds the prostate specific membrane antigen (PSMA) expressed on the surface of prostate epithelial cells and up-regulated in tumour cells. The sensitivity and specificity for prostate cancer involved lymph node detection has been reported as 62 to 75% and 72 to 86%, respectively, compared with sensitivities of 4% and 15% for computerised tomography and magnetic resonance imaging. (111)In-capromab pendetide imaging has proven to be an accurate, non-invasive tool for detecting and staging sites of recurrence in the post-prostatectomy patient as well as metastatic sites in the patient with newly diagnosed prostate cancer.

Purpose. The stability of a mixture of technetium Tc 99m sulfur colloid and lidocaine hydrochloride for up to eight hours was studied. Methods. Three vials of technetium Tc 99m sulfur colloid were compounded according to the manufacturer’s instructions. From each of the three vials, five samples were withdrawn into syringes with needles: 0.4, 0.45, 0.5, 0.63, and 1 mCi for testing after storage for zero, one, two, four, and eight hours, respectively. Each syringe contained the customary patient dose of 0.4 mCi at the time of testing. Fresh 0.9% sodium chloride injection was used to bring the volume of each syringe to 0.2 mL, and 0.2 mL of lidocaine hydrochloride 1% was added to bring the final volume to 0.4 mL. Measurements of pH, radiochemical purity, and particle size were conducted after the indicated storage times for each group of samples. Results. The pH of samples showed no substantial change over the eight-hour storage period, with individual values in the range of 4.5–5.5. Radiochemical purity did not change substantially, with values ranging from 98.9% to 99.9%. There was no meaningful change in the amount of radioactivity retained by filtration and no increase in particle size. Conclusion. Adding lidocaine hydrochloride 1% to syringes containing technetium Tc 99m sulfur colloid and storing the syringes for up to eight hours had no effect on the pH or radiochemical purity of the mixture or on the radioactivity retained by a filter.

To predict the optimal time for surgery after antibody administration, the population pharmacokinetics of (125)I-HuCC49deltaCH2 and (125)I-CC49 were characterized in 55 patients with colorectal cancers. A 2-compartment linear model was used to fit the pharmacokinetic data. Model stability and performance were assessed using a visual predictive check procedure. Different clinical trial designs were evaluated by simulation in combination with Bayesian estimation method to predict the optimal time for surgery. The results showed that HuCC49deltaCH2 had 65% faster clearance from blood circulation and 24% shorter mean residence time than CC49. Population pharmacokinetic analysis identified body weight as the only covariate to explain between-subject variability in clearance, intercompartmental flow rate, and volume of distribution. Model predictions indicated a wide interval for the optimal time of surgery, suggesting that it would be beneficial to individualize the time of surgery for each patient by measurement of antibody disposition. Clinical trial designs with at least 3 measurements of antibody disposition were found to be better than an empirical direct observation method for the optimal prediction of surgery time.

Background Many imaging methods have been used to detect neuroendocrine tumors of the gastrointestinal system. There is no gold standard for identifying the location of primary tumors and their potential metastases, and most conventional imaging techniques cannot detect tumors less than 1.0 cm in size. Methods The authors have investigated the use of 111In-pentetreotide as an imaging agent for abdominal neuroendocrine tumors. Results The agent is cleared rapidly by the kidneys and is primarily excreted intact with a biologic half-life of six hours. The largest radiation burden is to the spleen and kidneys. A nine-center study conducted in Europe involved 365 patients with gastroenteropancreatic neuroendocrine tumors that were also imaged by other methods. The results of 111In-pentetreotide were in agreement with those obtained by other methods for 79% of tumor locations. An additional 110 tumor localizations were detected that were not seen with conventional methods. The smallest gastrinoma imaged by 111In-pentetreotide was a 4-mm duodenal tumor. Conclusions Scintigraphy with 111In-pentetreotide is effective in visualizing various somatostatin receptors characteristic of neuroendocrine tumors of the gastrointestinal tract. Insulinomas, however, are not well imaged. Concurrent computed tomography scanning is advised to minimize the risk of missing liver metastases.

CC49 is an antitumor monoclonal antibody that is promising for use in radioimmunoguided surgery (RIGS). However, the murine antibody has been limited by human antimouse antibody (HAMA) response and slow clearance. This study examined the pharmacokinetics and tissue localization of a humanized domain-deleted CC49 antibody (HuCC49DeltaC(H)2 MAb) in humans.Twenty-one patients with colorectal carcinoma were given 1 mg intravenous (I.V.) bolus of HuCC49DeltaC(H)2 MAb radiolabeled with 2 mCi (125)I after thyroid blockade. The level of circulating HuCC49DeltaC(H)2 MAb was measured daily as precordial counts using a handheld gamma-detecting probe. Each patient underwent an exploratory laparotomy on postinjection days 3-20. Gamma counts were measured at normal organs, aortic bifurcation (AB), and both clinically evident and occult tumors.Precordial and AB gamma counts showed an excellent linear correlation. HuCC49DeltaC(H)2 MAb followed a two-compartment pharmacokinetic model. Normal organs and AB showed similar exposures to HuCC49DeltaC(H)2 MAb, while HuCC49DeltaC(H)2 MAb favorably distributed into tumors from day 3. Intestinal and metastatic liver lesions showed the highest partition coefficients. All patients showed no HAMA response.C(H)2 region deletion of HuCC49DeltaC(H)2 MAb did not alter the pharmacokinetics compared to murine CC49. The favorable partition coefficient K of HuCC49DeltaC(H)2 MAb into tumors supports its use in RIGS.

Background: CC49 is a monoclonal antibody directed against a pancarcinoma antigen (TAG-72) expressed by colorectal cancers. The use of murine CC49 in radioimmunoguided surgery (RIGS) was problematic because of the human anti-mouse antibodies (HAMA) generated. This study was designed to assess the clearance, safety, and effectiveness of localization of a complimentarity determining region (CDR)-grafted humanized domain-deleted antitumor CC49 antibody (HuCC49°CH2). Methods: After thyroid blockade, 1 mg of HuCC49°CH2 radiolabeled with 2 mCi of iodine-125 was administered. All patients subsequently underwent traditional exploration followed by a survey with the gamma-detecting probe. In five patients, exploration was performed 10 to 24 days after injection, when precordial counts were sufficiently low (

Aim and Background Radioimmunoguided surgery using radiolabeled NR-LU-10 Fab was evaluated as a method of intraoperative breast cancer detection. Methods Breast cancer patients were injected intravenously with 125I (74 MBq) labeled NR-LU-10 Fab (5 mg) and then underwent tumor excision 2, 4 or 7 days later, during which time the gamma detector probe was used to evaluate the primary tumor for evidence of radioactive uptake. Results Intraoperative probing revealed tumor localization in 7 of 10 patients (70%). Gamma probe counts of the excised tumor were elevated in all patients, although high counts in surrounding nonmalignant tissue obscured the ability to detect the tumor in vivo in 3 patients. One patient with bilateral breast cancer was found to have a separate focus of occult tumor in each breast using the gamma detector probe. Conclusions Radiolabeled NR-LU-10 Fab possesses favorable pharmokinetics and tumor-binding ability as a targeting agent. However, binding to nonmalignant tissue limits its role in the intraoperative evaluation of tumor margins in breast cancer patients. Its role in other malignancies should be explored.

Background: This prospective study was performed to ascertain the added benefit of lymphoscintigraphy to a standard method of intraoperative lymphatic mapping and sentinel node biopsy for breast cancer. Methods: Patients with invasive breast cancer were injected with 99m Tc sulfur colloid prior to sentinel node biopsy; preoperative lymphoscintigraphy was then performed in half of the patient population. Results: Sentinel node identification was possible in 45 of 50 patients (90%). All 14 patients (31%) with axillary nodal metastases had at least one histologically positive sentinel node (0% false negative rate). Lymphoscintigraphy revealed sentinel nodes in 17 of the 24 patients (70.8%) imaged. All 17 of these patients had one or more axillary sentinel nodes identified using intraoperative lymphatic mapping. In addition, 5 of 7 patients with a negative preoperative lymphoscintogram had an axillary sentinel lymph node(s) identified intraoperatively. None of the tumors showed drainage to the internal mammary lymph node chain by lymphoscintigraphy despite the fact that there were 5 patients with inner quadrant tumors. There was no significant advantage with respect to sentinel lymph node localization (91.7% versus 88.5%, P = not significant) or false negative rate (0%, both groups, P = not significant) in the group undergoing preoperative lymphoscintigraphy when compared with the patients in whom lymphoscintigraphy was not performed. Conclusions: Preoperative lymphoscintigraphy adds little additional information to intraoperative lymphatic mapping, and its routine use is not justified.

Radioimmunodetection, which takes advantage of tumor-specific or tumor-associated radiolabeled monoclonal antibodies or other biologic molecules to diagnose the extent of disease in cancer patients, has been of limited use in studies to date in patients with breast cancer. The difficulty is in finding an antibody that is both sensitive and specific enough to localize in breast tumors. This study undertook immunohistochemical and in vivo evaluation of tumor localization and biodistribution of NR-LU-10 Fab (antibody fragment) in breast tumors to determine its ability to bind selectively to malignant tissue. NR-LU-10 Fab recognizes a pancarcinoma glycoprotein antigen found on tumors of epithelial cell origin. NR-LU-10 Fab reacted with 6/6 (100%) breast cancer cell lines and 14/16 (87.5%) breast tumors with varying degrees of immunostaining intensities. Athymic mice bearing ZR-75-1 breast cancer xenografts were injected with 125 I-labeled NR-LU-10 Fab (12 μg/5 μCi) and sacrificed at fixed time intervals. These studies demonstrated the highest tumor uptake of labeled Fab at 12 h postinjection (4.58 ± 1.59% of injected dose/gram [% ID/g] of tissue); this gradually decreased to 0.13 ± 0.05% ID/g of tissue by 72 h postinjection of the radiolabeled Fab. Biolocalization to normal tissues was as predicted for a Fab fragment; i.e ., initially high in clearance organs (kidney), followed by rapid clearance over the 72-h test period. NR-LU-10 Fab displays adequate breast tumor localization with minimal biolocalization to normal tissues, thus supporting its potential use in radioimmunoscintigraphy and the RIGS® system (radioimmunoguided surgery).

Radioimmunoguided Surgery techniques which use radiolabeled tumor specific markers and an intraoperative detector in an attempt to improve therapy and survival in patients with cancer have been under development for over fifteen years. Monoclonal antibody (MAb) CC49 is a second-generation murine IgG1 which has improved localization properties over its predecessor, MAb B72.3, and has been studied in a number of patients. In order to determine the pharmacokinetics of iodine-125 (125I) CC49 MAb, size-exclusion, high-performance liquid chromatography (HPLC) was used to assess radioactive components in serum and urine following administration of the drug to colon cancer patients.Five patients received an intravenous infusion of 10 mg of MAb CC49 labeled with 2 mCi 125I. Following infusion, serum and urine specimens were collected from patients at predetermined time intervals prior to surgery. HPLC analysis of these specimens was completed to determine the radioactive species in each sample.Serum and urine specimens showed that serum levels of CC49 decrease exponentially and become unmeasurable by day 14 (half-life 1.89 days, +/- 0.19), with a steady, low-level of free 125I measurable in postinjection serum until day 21 after infusion. There was no evidence of MAb fragmentation or antibody:antigen (Ab:Ag) complex formation in serum, and no evidence of whole MAb, F(ab')2, or Fab fragment excretion in urine. Preinjection sera with MAb added in vitro also failed to demonstrate Ab:Ag complex formation. Analysis of urine showed low level excretion of free 125I which peaked by day 1 and declined exponentially through day 21, with a very low molecular weight (1 kDa) MAb fragment excreted in urine between 1 and 21 days.Radioiodinated 125I CC49 MAb remains in serum of cancer patients approximately 14 days, and tissue radioactivity beyond this time may reflect tissue sequestered MAb and/or free 125I and not "bloo pool" radioactivity. CC49 MAb appears to be deiodinated in small but significant quantities before it is metabolized, and clearance of radioactivity is mainly in free 125I form in urine. Measurable quantities of a1 Kda MAb fragment in urine and not serum may suggest a renal mechanism of MAb metabolism, but may also represent a metabolic end product of MAb metabolism with a very short serum half-life (T1/2) which accumulates in urine.

Background. CC83, a second-generation monoclonal antibody (MAb) against tumor-associated glycoprotein TAG-72 has been shown to have a higher affinity constant than the anti-TAG MAbs CC49 and B72.3. Clinical studies have shown the effectiveness of both CC49 and B72.3 radiolabeled MAbs in localizing colorectal carcinoma with a hand-held gamma-detecting probe during operation. This current study was designed to assess the safety and tumor-binding ability of radiolabeled CC83 MAb in this setting. Methods. Seventeen patients with recurrent colorectal cancer underwent intravenous injection with CC83 Mab radiolabeled with iodine 125 (2.0 mCi 125 I/0.2 mg CC83 MAb). Exploratory laparotomy was carried out 21 to 28 days after injection, consisting of a thorough traditional exploration followed by a survey with a hand-held gamma-detecting probe. All traditionally suspicious and probe-positive tissue was either biopsied or resected and subsequently examined for the presence of carcinoma by using routine histochemical staining techniques. Results. Thirty-two sites were identified as suspicious for cancer by traditional surgical exploration and 39 through intraoperative survey with a hand-held gamma-detecting probe in the seventeen patients completing the study. Biopsy or resection yielded 27 tumor sites when tissue was evaluated by using routine hematoxylin-eosin staining. All 27 tumor sites were localized by the radiolabeled CC83 MAb, whereas 12 additional sites were RIGS positive but hematoxylin-eosin negative, resulting in a sensitivity and positive predictive value of 100% and 69%, respectively. Traditional methods of exploration detected 23 of 27 tumor sites (85% sensitivity), and nine false-positive sites were recorded (72% positive predictive value). Occult tumor was found by using CC83 MAb in four (15%) of 27 sites, altering the surgical plan in three patients. Conclusions. This initial study indicates that CC83 MAb, when used with RIGS, is safe and sensitive in detecting recurrent intraabdominal colorectal cancer.

Somatostatin, a naturally occurring 14-amino acid peptide, can be thought of as an anti-growth hormone and functional down-regulator of sensitive tissue. Most neuroendocrine tumors seem to possess somatostatin receptors in sufficient abundance to allow successful scintigraphic imaging with radiolabeled somatostatin congeners. Several of these, including Indium-111-DTPA Pentetreotide (Octreoscan [Mallinckrodt Medical, St. Louis, MO]), which was approved for clinical use by the Food and Drug Administration in June 1994, have been of considerable value in scintigraphically identifying various neuroendocrine tumors. The Octreoscan compares favorably with other imaging modalities. The success of somatostatin receptor imaging in evaluating patients with suspected neuroendocrine tumors, including identifying otherwise radiographically occult lesions, has resulted in ranking somatostatin receptor imaging as the prime imaging procedure in patients with suspected neuroendocrine tumors at The Ohio State University.

The diffusion properties of the brain cortical extracellular space have never been examined in models of inflammation, even though inflammation can cause increased blood-brain barrier permeability. Uptake of intravascular 125I-labelled albumin and the diffusion of the tetramethylammonium ion within the brain extracellular space was measured in an experimental brain abscess to determine the effect of acute inflammation upon blood-brain barrier permeability and diffusion properties of the cortical extracellular space. The blood-brain transfer constant for albumin was increased in the abscess region, indicating that an increase in blood-brain barrier permeability occurred in animals inoculated with a weakly pathogenic strain of Staphylococcus aureus. The volume fraction of the extracellular space, as measured by the diffusion of tetramethylammonium ion, ranged from 0.19 to 0.23 in bacteria inoculated subjects and from 0.21 to 0.22 in controls. The tortuosity of the extracellular space ranged from 1.40 to 1.42 in bacteria inoculated subjects and was 1.39 in controls. These results showed that the volume fraction and tortuosity of the cortical extracellular space were not affected by inflammation even though vascular permeability was increased. This result was supported by the finding that brain water content, measured in the same animals, was increased to a non-significant extent in the bacteria inoculated subjects. These findings lead to the conclusion that acute inflammation induced by a weak pathogen can cause increased blood-brain barrier permeability without a significant change in the diffusion properties of the brain cortical space.

The Neoprobe Model 1000 hand-held gamma detector, in combination with the murine monoclonal antibody (MAb) B72.3 can successfully intraoperatively target both primary and recurrent colorectal cancer. Because of the shortcomings of this system (length of time needed to clear unbound MAb and heterogeneous staining of cancer cells), new MAbs are under investigation. NR-LU-10 IgG and its FAB fragment were evaluated with the Neoprobe gamma detector in a nude mouse model. NR-LU-10 is a pancarcinoma IgG 2b antibody that recognizes an oncofetal glycoprotein antigen that is expressed by most carcinomas. Animals were injected intraperitoneally with 125 I-labeled IgG, 125 I, or technetium 99m ( 99m Tc)-labeled Fab fragment. The Neoprobe gamma detector and standard gamma well counts provided biodistribution and pharmacokinetic data. The Fab fragment achieved a 5:1 tumor to blood-pool background (BPB) ratio in only 66 hr, whereas the whole MAb required 14 days. Technetium did not appear to be an adequate isotope for this system because of its short half-life. Autoradiographs performed for both the 125 I-labeled NR-LU-10 IgG and its 125 I-labeled Fab fragment (but not 99m Tc-labeled Fab) localized well in this model and gave adequate tumor to BPB and tissue ratios. Use of the 125 I-labeled Fab significantly decreased the time required for clearance of the MAb radionuclide complex from the blood and tissue background, thus providing earlier tumor localization in the Radioimmunoguided Surgery (RIGS) system.

Background 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is widely used in diagnostic cancer imaging. However, the use of 18F-FDG in PET-based imaging is limited by its specificity and sensitivity. In contrast, anti-TAG (tumor associated glycoprotein)-72 monoclonal antibodies are highly specific for binding to a variety of adenocarcinomas, including colorectal cancer. The aim of this preliminary study was to evaluate a complimentary determining region (CDR)-grafted humanized CH2-domain-deleted anti-TAG-72 monoclonal antibody (HuCC49deltaCH2), radiolabeled with iodine-124 (124I), as an antigen-directed and cancer-specific targeting agent for PET-based imaging. Methods HuCC49deltaCH2 was radiolabeled with 124I. Subcutaneous tumor implants of LS174T colon adenocarcinoma cells, which express TAG-72 antigen, were grown on athymic Nu/Nu nude mice as the xenograft model. Intravascular (i.v.) and intraperitoneal (i.p.) administration of 124I-HuCC49deltaCH2 was then evaluated in this xenograft mouse model at various time points from approximately 1 hour to 24 hours after injection using microPET imaging. This was compared to i.v. injection of 18F-FDG in the same xenograft mouse model using microPET imaging at 50 minutes after injection. Results At approximately 1 hour after i.v. injection, 124I-HuCC49deltaCH2 was distributed within the systemic circulation, while at approximately 1 hour after i.p. injection, 124I-HuCC49deltaCH2 was distributed within the peritoneal cavity. At time points from 18 hours to 24 hours after i.v. and i.p. injection, 124I-HuCC49deltaCH2 demonstrated a significantly increased level of specific localization to LS174T tumor implants (p = 0.001) when compared to the 1 hour images. In contrast, approximately 50 minutes after i.v. injection, 18F-FDG failed to demonstrate any increased level of specific localization to a LS174T tumor implant, but showed the propensity toward more nonspecific uptake within the heart, Harderian glands of the bony orbits of the eyes, brown fat of the posterior neck, kidneys, and bladder. Conclusions On microPET imaging, 124I-HuCC49deltaCH2 demonstrates an increased level of specific localization to tumor implants of LS174T colon adenocarcinoma cells in the xenograft mouse model on delayed imaging, while 18F-FDG failed to demonstrate this. The antigen-directed and cancer-specific 124I-radiolabled anti-TAG-72 monoclonal antibody conjugate, 124I-HuCC49deltaCH2, holds future potential for use in human clinical trials for preoperative, intraoperative, and postoperative PET-based imaging strategies, including fused-modality PET-based imaging platforms.

Radioimmunoguided surgery (RIGS) has been employed intraoperatively in cases of colorectal cancer to assess the extent of local tumor spread and metastatic disease. This technique uses radiolabeled monoclonal antibodies (MAbs) directed against tumor-associated antigens, and a hand-held gamma-detection probe to detect the radiolabel fixed to tumor tissue. Recently introduced is an MAb directed against tumor-associated glycoprotein (anti-TAG), CC49. Sixty patients were entered into the initial study. Eighteen of 21 (86%) primary tumors were localized by the CC49 MAb and the gamma-detecting probe. Twenty-nine of 30 (97%) recurrent tumors were localized. Antibody dose did not affect localization. Specimens were divided into tissue types I through IV, based on antibody localization and hematoxylin and eosin (H&E) staining: type I, RIGS (-) and histologically (-); type II, RIGS (-) and histologically (+); type III, RIGS (+) and histologically (-); type IV, RIGS (+) and histologically (+). Type IV tissue were further classified by whether they were grossly apparent, IVa, or grossly inapparent, IVb (occult). Occult tumor found by RIGS and confirmed by H&E staining (type IV) had localization ratios similar to RIGS-positive, histology-negative tissue (type III). Traditionally found cancer (type IV) had significantly higher ratios. In 12 of 24 patients (50%) with primary tumors and 14 of 30 patients (47%) with recurrent tumors, RIGS with CC49 altered the planned operative procedure. Radioimmunoguided surgery with CC49 provides useful, immediate intraoperative information not available by other techniques.

We developed a novel dual-modal contrast agent for the structural and functional imaging of cancer. The contrast agent was fabricated by encapsulating indocyanine green (ICG) in poly(lactic-co-glycolic acid) (PLGA) microbubbles using a modified double-emulsion method. More stabilized absorption and fluorescence emission characteristics were observed for aqueous and plasma suspensions of ICG-encapsulated microbubbles. The technical feasibility of concurrent structural and functional imaging was demonstrated through a series of benchtop tests in which the aqueous suspension of ICG-encapsulated microbubbles was injected into a transparent tube embedded in an Intralipid phantom at different flow rates and concentrations. Concurrent fluorescence imaging and B-mode ultrasound imaging successfully captured the changes of microbubble flow rate and concentration with high linearity and accuracy. One potential application of the proposed ICG-encapsulated PLGA microbubbles is for the identification and characterization of peritumoral neovasculature for enhanced coregistration between tumor structural and functional boundaries in ultrasound-guided near-infrared diffuse optical tomography.

• Preliminary data using B72.3 murine monoclonal antibody labeled with iodine 125 suggested that both clinically apparent as well as occult sites of colorectal cancer could be identified intraoperatively using a hand-held gamma detecting probe. We report the preliminary data of a multicenter trial of this approach in patients with primary or recurrent colorectal cancer. One hundred four patients with primary, suspected, or known recurrent colorectal cancer received an intravenous infusion of 1 mg of B72.3 monoclonal antibody radiolabeled with 7.4×10 Bq of iodine 125. Twenty-six patients with primary colorectal cancer and 72 patients with recurrent colorectal cancer were examined. Using the gamma detecting probe, 78% of the patients had localization of the antibody in their tumor; this included 75% of primary tumor sites and 63% of all recurrent tumor sites; 9.2% of all tumor sites identified represented occult sites detected only with the gamma detecting probe. The overall sensitivity was 77% and a predictive value of a positive detection was 78%. A total of 30 occult sites in 26 patients were identified. In patients with recurrent cancer, the antibody study provided unique data that precluded resection in 10 patients, and in another eight patients it extended the potentially curative procedure. ( Arch Surg . 1991;126:349-352)

The affinity of MoAb CO 17-1A and expression of its antigenic target were studied on uninfected and mycoplasma-infected colorectal cancer cell lines SW 1116 and SW 948. Binding of 125I-labeled CO 17-1A to SW 1116 cells was quantified at 37 degrees C by determination of the affinity constant (Ka) and the number of antigenic receptor sites (r) per cell using Scatchard plots. When mycoplasma-free SW 1116 cells were used as targets, Ka was 0.92 +/- 0.06 x 10(8) M-1 and r = 1.32 +/- 0.14 x 10(6) at 37 degrees C. One batch of unspeciated, mycoplasma-infected SW 116 cells had reduced affinity and a decreased number of antigenic receptor sites per cell for 125I-labeled 17-1A, while another batch of infected SW 1116 cells had a 4- to 5-fold increase in r and diminished Ka for the antibody compared with uninfected cells. When unspeciated, mycoplasma-infected SW 948 cells were exposed to 125I-labeled 17-1A and the data subjected to Scatchard analysis, the affinity of the antibody deviated markedly from linearity and rendered analysis for Ka and r meaningless. These data indicate that mycoplasma infection can produce variable effects on the cellular expression of antigenic receptor sites and the affinity of antibody for its target, and emphasize the importance of using mycoplasma-free cell lines in studies of these parameters.

Tumors marked with a radiolabeled antibody may be located by two different techniques. The first is the diagnostic use of a gamma camera to produce an image. The second is the clinical use of a gamma-sensitive probe to ‘home in’ on tumors intraoperatively. Since the two techniques are quite different, it is not surprising that they differ in advantages, limitations, and design.

This study was undertaken to define the limits for the radioimmunodetection of minimal deposits of colorectal cancer cells using a hand held gamma probe. 125I labeled monoclonal antibody 17-1A and its F(ab')2 fragments were reacted in vitro with cells of the human colorectal cancer line SW 1116. The limits of sensitivity of the probe were determined by injecting doubling dilutions of 125I-antibody coated SW 1116 cells ranging from 10(7) to 3.9 x 10(4) subserosally at 2 cm intervals into 60 cm segments of freshly obtained autopsy or surgical specimens of human colon. A linear relationship was observed between the number of cells injected and the number of counts obtained with either the probe or well counter. As few as 6.25 x 10(5) 125I-antibody coated cells (less than 1 mm3) were detected under experimentally defined conditions by an earlier version of the probe, and 3.9 x 10(4) coated cells (much less than 1 mm3) could be detected by the currently available model. Although the count rates were less than 5% of those obtained by well counter, nevertheless, these were 10-25 times greater than background and allowed the detection of tumor cell deposits that otherwise would not have been discernible by either palpation or external scintigraphy. These findings, in conjunction with ongoing clinical studies, suggest that the hand held gamma probe may increase the usefulness of monoclonal antibodies for the radioimmunodetection of cancer.