Linker engineering in anti-TAG-72 antibody fragments optimizes biophysical properties, serum half-life, and high-specificity tumor imaging.

Antibody (Ab) fragments have great clinical potential as cancer therapeutics and diagnostics. Their small size allows for fast clearance from blood, low immunoreactivity, better tumor penetration, and simpler engineering and production. The smallest fragment derived from a full-length IgG that retains binding to its antigen, the single-chain variable fragment (scFV), is engineered by fusing the variable light and variable heavy domains with a peptide linker. Along with switching the domain orientation, altering the length and amino acid sequence of the linker can significantly affect scFV binding, stability, quaternary structure, and other biophysical properties. Comprehensive studies of these attributes in a single scaffold have not been reported, making design and optimization of Ab fragments challenging. Here, we constructed libraries of 3E8, an Ab specific to tumor-associated glycoprotein 72 (TAG-72), a mucinous glycoprotein overexpressed in 80% of adenocarcinomas. We cloned, expressed, and characterized scFVs, diabodies, and higher-order multimer constructs with varying linker compositions, linker lengths, and domain orientations. These constructs dramatically differed in their oligomeric states and stabilities, not only because of linker and orientation but also related to the purification method. For example, protein L-purified constructs tended to have broader distributions and higher oligomeric states than has been reported previously. From this library, we selected an optimal construct, 3E8.G4S, for biodistribution and pharmacokinetic studies and in vivo xenograft mouse PET imaging. These studies revealed significant tumor targeting of 3E8.G4S with a tumor-to-background ratio of 29:1. These analyses validated 3E8.G4S as a fast, accurate, and specific tumor-imaging agent.

Feasibility of a multimodal (18)F-FDG-directed lymph node surgical excisional biopsy approach for appropriate diagnostic tissue sampling in patients with suspected lymphoma.

BACKGROUND: F-FDG PET/CT imaging is widely utilized in the clinical evaluation of patients with suspected or documented lymphoma. The aim was to describe our cumulative experience with a multimodal (18)F-FDG-directed lymph node surgical excisional biopsy approach in patients with suspected lymphoma. METHODS: Thirteen patients (mean age 51 (± 16;22-76) years), with suspected new or suspected recurrent lymphoma suggested by (18)F-FDG-avid lesions seen on prior diagnostic whole-body PET/CT imaging, were injected IV with (18)F-FDG prior to undergoing same-day diagnostic lymph node surgical excisional biopsy in the operating room. Various (18)F-FDG detection strategies were used on the day of surgery, including, (1) same-day pre-resection patient PET/CT; (2) intraoperative gamma probe assessment; (3) clinical scanner specimen PET/CT imaging of whole surgically excised tissue specimens; (4) specimen gamma well counts; and/or (5) same-day post-resection patient PET/CT. RESULTS: Same-day (18)F-FDG injection dose was 14.8 (± 2.4;12.5-20.6) millicuries or 548 (± 89;463-762) megabecquerels. Sites of (18)F-FDG-avid lesions were 4 inguinal, 3 cervical, 3 abdominal/retroperitoneal, 2 axillary, and 1 gluteal region subcutaneous tissue. Same-day pre-resection patient PET/CT was performed on 6 patients. Intraoperative gamma probe assessment was performed on 13 patients. Clinical scanner PET/CT imaging of whole surgically excised tissue specimens was performed in 10 cases. Specimen gamma well counts were performed in 6 cases. Same-day post-resection patient PET/CT imaging was performed on 8 patients. Time from (18)F-FDG injection to same-day pre-resection patient PET/CT, intraoperative gamma probe assessment, and same-day post-resection patient PET/CT were 76 (± 8;64-84), 240 (± 63;168-304), and 487 (± 104;331-599) minutes, respectively. Time from (18)F-FDG injection to clinical scanner PET/CT of whole surgically excised tissue specimens was 363 (± 60;272-446) minutes. Time from (18)F-FDG injection to specimen gamma well counts was 591 (± 96;420-689) minutes. Intraoperative gamma probe assessment successfully identified (18)F-FDG-avid lesions in 12/13 patients. Histopathologic evaluation confirmed lymphoma in 12/13 patients and benign disease in 1/13 patients. CONCLUSIONS: A multimodal approach to (18)F-FDG-directed lymph node surgical excisional biopsy for suspected lymphoma is technically feasible for guiding appropriate diagnostic tissue sampling of lymph nodes seen as (18)F-FDG-avid lesions on diagnostic (18)F-FDG PET/CT imaging.

Comparison of two threshold detection criteria methodologies for determination of probe positivity for intraoperative in situ identification of presumed abnormal 18F-FDG-avid tissue sites during radioguided oncologic surgery.

BACKGROUND: Intraoperative in situ identification of (18)F-FDG-avid tissue sites during radioguided oncologic surgery remains a significant challenge for surgeons. The purpose of our study was to evaluate the 1.5-to-1 ratiometric threshold criteria method versus the three-sigma statistical threshold criteria method for determination of gamma detection probe positivity for intraoperative in situ identification of presumed abnormal (18)F-FDG-avid tissue sites in a manner that was independent of the specific type of gamma detection probe used. METHODS: From among 52 patients undergoing appropriate in situ evaluation of presumed abnormal (18)F-FDG-avid tissue sites during (18)F-FDG-directed surgery using 6 available gamma detection probe systems, a total of 401 intraoperative gamma detection probe measurement sets of in situ counts per second measurements were cumulatively taken. RESULTS: For the 401 intraoperative gamma detection probe measurement sets, probe positivity was successfully met by the 1.5-to-1 ratiometric threshold criteria method in 150/401 instances (37.4%) and by the three-sigma statistical threshold criteria method in 259/401 instances (64.6%) (P < 0.001). Likewise, the three-sigma statistical threshold criteria method detected true positive results at target-to-background ratios much lower than the 1.5-to-1 target-to-background ratio of the 1.5-to-1 ratiometric threshold criteria method. CONCLUSIONS: The three-sigma statistical threshold criteria method was significantly better than the 1.5-to-1 ratiometric threshold criteria method for determination of gamma detection probe positivity for intraoperative in situ detection of presumed abnormal (18)F-FDG-avid tissue sites during radioguided oncologic surgery. This finding may be extremely important for reshaping the ongoing and future research and development of gamma detection probe systems that are necessary for optimizing the in situ detection of radioisotopes of higher-energy gamma photon emissions used during radioguided oncologic surgery.

18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues.

BACKGROUND: 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic (18)F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals. METHODS: (18)F-FDG-avid lesions (not surgically manipulated or altered during (18)F-FDG-directed surgery, and visualized both on preoperative and postoperative (18)F-FDG PET/CT imaging) and corresponding background tissues were assessed for (18)F-FDG accumulation on same-day preoperative and postoperative (18)F-FDG PET/CT imaging. Multiple patient variables and (18)F-FDG-avid lesion variables were examined. RESULTS: For the 32 (18)F-FDG-avid lesions making up the final (18)F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative (18)F-FDG PET/CT scans were 73 (± 3, 70-78) and 530 (± 79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean (18)F-FDG-avid lesion SUV(max) values were 7.7 (± 4.0, 3.6-19.5) and 11.3 (± 6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUV(max) values were 2.3 (± 0.6, 1.0-3.2) and 2.1 (± 0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUV(max) ratios were 3.7 (± 2.3, 1.5-9.8) and 5.8 (± 3.6, 1.6-16.2), respectively, (P < 0.001). CONCLUSIONS: (18)F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for (18)F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the (18)F-FDG-avid lesion SUV(max) values, decreased background SUV(max) values, and increased lesion-to-background SUV(max) ratios seen from preoperative to postoperative (18)F-FDG PET/CT imaging have great potential for allowing for the integrated, real-time use of (18)F-FDG PET/CT imaging in conjunction with (18)F-FDG-directed interventional radiology biopsy and ablation procedures and (18)F-FDG-directed surgical procedures, as well as have far-reaching impact on potentially re-shaping future thinking regarding the "most optimal" injection-to-scan acquisition time interval for all routine diagnostic (18)F-FDG PET/CT oncologic imaging.

A multifaceted intervention to improve compliance with process measures for ICU clinician communication with ICU patients and families.

RATIONALE: Despite recommendations supporting the importance of clinician-family communication in the ICU, this communication is often rated as suboptimal in frequency and quality. We employed a multifaceted behavioral-change intervention to improve communication between families and clinicians in a statewide collaboration of ICUs. OBJECTIVES: Our primary objective was to examine whether the intervention resulted in increased compliance with process measures that targeted clinician-family communication. As secondary objectives, we examined the ICU-level characteristics that might be associated with increased compliance (open vs closed, teaching vs nonteaching, and medical vs medical-surgical vs surgical) and patient-specific outcomes (mortality, length of stay). METHODS: The intervention was a multifaceted quality improvement approach targeting process measures adapted from the Institute of Health Improvement and combined into two "bundles" to be completed either 24 or 72 hours after ICU admission. MEASUREMENTS AND MAIN RESULTS: Significant increases were seen in full compliance for both day 1 and day 3 process measures. Day 1 compliance improved from 10.7% to 83.8% after 21 months of intervention (p<0.001). Day 3 compliance improved from 1.6% to 28.8% (p<0.001). Improvements in compliance varied across ICU type with less improvement in open, nonteaching, and mixed medical-surgical ICUs. Patient-specific outcome measures were unchanged, although there was a small increase in patients discharged from ICU to inpatient hospice (p=0.002). CONCLUSIONS: We found that a multifaceted intervention in a statewide ICU collaborative improved compliance with specific process measures targeting communication with family members. The effect of the intervention varied by ICU type.

Site specific discrete PEGylation of (124)I-labeled mCC49 Fab' fragments improves tumor MicroPET/CT imaging in mice.

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.

Intraoperative detection of ¹8F-FDG-avid tissue sites using the increased probe counting efficiency of the K-alpha probe design and variance-based statistical analysis with the three-sigma criteria.

BACKGROUND: Intraoperative detection of (18)F-FDG-avid tissue sites during 18F-FDG-directed surgery can be very challenging when utilizing gamma detection probes that rely on a fixed target-to-background (T/B) ratio (ratiometric threshold) for determination of probe positivity. The purpose of our study was to evaluate the counting efficiency and the success rate of in situ intraoperative detection of (18)F-FDG-avid tissue sites (using the three-sigma statistical threshold criteria method and the ratiometric threshold criteria method) for three different gamma detection probe systems. METHODS: Of 58 patients undergoing (18)F-FDG-directed surgery for known or suspected malignancy using gamma detection probes, we identified nine (18)F-FDG-avid tissue sites (from amongst seven patients) that were seen on same-day preoperative diagnostic PET/CT imaging, and for which each (18)F-FDG-avid tissue site underwent attempted in situ intraoperative detection concurrently using three gamma detection probe systems (K-alpha probe, and two commercially-available PET-probe systems), and then were subsequently surgical excised. RESULTS: The mean relative probe counting efficiency ratio was 6.9 (± 4.4, range 2.2-15.4) for the K-alpha probe, as compared to 1.5 (± 0.3, range 1.0-2.1) and 1.0 (± 0, range 1.0-1.0), respectively, for two commercially-available PET-probe systems (P < 0.001). Successful in situ intraoperative detection of 18F-FDG-avid tissue sites was more frequently accomplished with each of the three gamma detection probes tested by using the three-sigma statistical threshold criteria method than by using the ratiometric threshold criteria method, specifically with the three-sigma statistical threshold criteria method being significantly better than the ratiometric threshold criteria method for determining probe positivity for the K-alpha probe (P = 0.05). CONCLUSIONS: Our results suggest that the improved probe counting efficiency of the K-alpha probe design used in conjunction with the three-sigma statistical threshold criteria method can allow for improved detection of 18F-FDG-avid tissue sites when a low in situ T/B ratio is encountered.

Mathematical model of colitis-associated colon cancer.

As a result of chronic inflammation of their colon, patients with ulcerative colitis or Crohn's disease are at risk of developing colon cancer. In this paper, we consider the progression of colitis-associated colon cancer. Unlike normal colon mucosa, the inflammed colon mucosa undergoes genetic mutations, affecting, in particular, tumor suppressors TP53 and adenomatous polyposis coli (APC) gene. We develop a mathematical model that involves these genes, under chronic inflammation, as well as NF-κB, ß-catenin, MUC1 and MUC2. The model demonstrates that increased level of cells with TP53 mutations results in abnormal growth and proliferation of the epithelium; further increase in the epithelium proliferation results from additional APC mutations. The model may serve as a conceptual framework for further data-based study of the early stage of colon cancer.

Multimodal imaging and detection strategy with 124 I-labeled chimeric monoclonal antibody cG250 for accurate localization and confirmation of extent of disease during laparoscopic and open surgical resection of clear cell renal cell carcinoma.

Renal cell carcinoma (RCC) accounts for approximately 85% to 90% of all primary kidney malignancies, with clear cell RCC (ccRCC) constituting approximately 70% to 85% of all RCCs. This study describes an innovative multimodal imaging and detection strategy that uses (124)I-labeled chimeric monoclonal antibody G250 ((124)I-cG250) for accurate preoperative and intraoperative localization and confirmation of extent of disease for both laparoscopic and open surgical resection of ccRCC. Two cases presented herein highlight how this technology can potentially guide complete surgical resection and confirm complete removal of all diseased tissues. This innovative (124)I-cG250 (ie, (124)I-girentuximab) multimodal imaging and detection approach, which would be clinically very useful to urologic surgeons, urologic medical oncologists, nuclear medicine physicians, radiologists, and pathologists who are involved in the care of ccRCC patients, holds great potential for improving the diagnostic accuracy, operative planning and approach, verification of disease resection, and monitoring for evidence of disease recurrence in ccRCC patients.

Repeat hepatectomy for metastatic colorectal cancer is safe but marginally effective.

BACKGROUND: Although hepatectomy for metastatic colorectal cancer (mCRC) offers prolonged survival in up to 40% of people, recurrence rates are high, approaching 70%. Many patients experience recurrent disease in the liver after initial hepatectomy. We examined our experience with repeat hepatectomy for mCRC. METHODS: After Institutional Review Board approval, we reviewed the records of all patients at a single institution who underwent hepatectomy for mCRC. Repeat hepatectomy was defined as partial liver resection any time after the initial hepatectomy for recurrent mCRC. We estimated time to recurrence and survival by using the Kaplan-Meier method and compared outcomes between groups by using the log-rank test. RESULTS: From 1998 to 2008, 405 patients underwent hepatectomy for mCRC, and 215 (53%) experienced disease recurrence at a median of 13 months. Of 150 patients with liver-only or liver-predominant recurrence, 52 (35%) underwent repeat hepatectomy. The median time to recurrence after repeat hepatectomy was 10 months, and median overall survival was 19 months. There was one (1.9%) perioperative death, and there were 14 (27%) major complications. The median overall survival in the repeat hepatectomy group from the time of recurrence after initial hepatectomy was 22 months, compared with 15 months in the 98 patients with liver recurrence who were not selected for repeat hepatectomy (P=0.02). CONCLUSIONS: Repeat hepatectomy for mCRC is feasible in highly selected patients, with acceptable perioperative morbidity and mortality. Although repeat hepatectomy should be considered, recurrence rates are high. Although the initial hepatectomy for mCRC is potentially curative, recurrence of metastatic disease in the liver is unlikely to be cured.

Antigen-directed cancer surgery for primary colorectal cancer: 15-year survival analysis.

BACKGROUND: 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. METHODS: 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 (125)I-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. RESULTS: 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. CONCLUSIONS: 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.

Retrospective review of pelvic malignancies undergoing total pelvic exenteration.

BACKGROUND: In patients with locally advanced or recurrent pelvic malignancies, total pelvic exenteration (TPE) may be necessary for curative treatment. Despite improvements in mortality rates since TPE was first described, morbidity rates remain high due to the extensive resection and the aggressiveness of these tumors. We have studied the outcomes of TPE surgery performed at our institution. METHODS: Fifty-three patients with various pelvic pathologies underwent TPE between 2004 and 2010. Patients were divided into two groups based on pathology: colorectal (n = 36) versus non-colorectal (n = 17) malignancies. Demographics, operative reports, pathology reports, periprocedural events, and outcomes were analyzed. Comparison of the two groups was performed using student's t-test and Fisher's exact test. Survival curves were constructed using the Kaplan-Meier method and compared using the log rank test. RESULTS: The colorectal and non-colorectal groups were similar in demographics, operative times, length of stay, estimated blood loss, and rates of preoperative and intraoperative radiation use. Chemotherapy use was increased in the colorectal group compared with the non-colorectal group (55.6% vs. 23.5%, P = 0.04). Complication rates were similar: 86% in the colorectal group and 76% in the non-colorectal group. In the colorectal group, 27.8% of patients developed perineal abscesses, whereas no patients developed these complications in the non-colorectal group (P = 0.02). No survival difference was seen in primary versus recurrent colorectal tumors; however, within the colorectal group there was a survival advantage when comparing R0 resection to R1 and R2 resection combined. Median survival rates were 27.3 months for R0 resection and 10.7 months for R1 and R2 resection combined. The median survival was 21.4 months for the colorectal group and 6.9 months for the non-colorectal group (P = 0.002). CONCLUSIONS: Patients undergoing TPE for colorectal tumors have improved survival when compared with patients undergoing exenteration for pelvic malignancies of other origins. Within the colorectal group, the extent of resection demonstrated a significant survival benefit of an R0 resection compared with R1 and R2 resections. Despite TPE carrying a high morbidity rate, mortality rates have improved and careful patient selection can optimize outcomes.

Multimodal imaging and detection approach to 18F-FDG-directed surgery for patients with known or suspected malignancies: a comprehensive description of the specific methodology utilized in a single-institution cumulative retrospective experience.

BACKGROUND: (18)F-FDG PET/CT is widely utilized in the management of cancer patients. The aim of this paper was to comprehensively describe the specific methodology utilized in our single-institution cumulative retrospective experience with a multimodal imaging and detection approach to (18)F-FDG-directed surgery for known/suspected malignancies. METHODS: From June 2005-June 2010, 145 patients were injected with (18)F-FDG in anticipation of surgical exploration, biopsy, and possible resection of known/suspected malignancy. Each patient underwent one or more of the following: (1) same-day preoperative patient diagnostic PET/CT imaging, (2) intraoperative gamma probe assessment, (3) clinical PET/CT specimen scanning of whole surgically resected specimens (WSRS), research designated tissues (RDT), and/or sectioned research designated tissues (SRDT), (4) micro PET/CT specimen scanning of WSRS, RDT, and/or SRDT, (5) total radioactivity counting of each SRDT piece by an automatic gamma well counter, and (6) same-day postoperative patient diagnostic PET/CT imaging. RESULTS: Same-day (18)F-FDG injection dose was 15.1 (± 3.5, 4.6-26.1) mCi. Fifty-five same-day preoperative patient diagnostic PET/CT scans were performed. One hundred forty-two patients were taken to surgery. Three of the same-day preoperative patient diagnostic PET/CT scans led to the cancellation of the anticipated surgical procedure. One hundred forty-one cases utilized intraoperative gamma probe assessment. Sixty-two same-day postoperative patient diagnostic PET/CT scans were performed. WSRS, RDT, and SRDT were scanned by clinical PET/CT imaging and micro PET/CT imaging in 109 and 32 cases, 33 and 22 cases, and 49 and 26 cases, respectively. Time from (18)F-FDG injection to same-day preoperative patient diagnostic PET/CT scan, intraoperative gamma probe assessment, and same-day postoperative patient diagnostic PET/CT scan were 73 (± 9, 53-114), 286 (± 93, 176-532), and 516 (± 134, 178-853) minutes, respectively. Time from (18)F-FDG injection to scanning of WSRS, RDT, and SRDT by clinical PET/CT imaging and micro PET/CT imaging were 389 (± 148, 86-741) and 458 (± 97, 272-656) minutes, 619 (± 119, 253-846) and 661 (± 117, 433-835) minutes, and 674 (± 186, 299-1068) and 752 (± 127, 499-976) minutes, respectively. CONCLUSIONS: Our multimodal imaging and detection approach to (18)F-FDG-directed surgery for known/suspected malignancies is technically and logistically feasible and may allow for real-time intraoperative staging, surgical planning and execution, and determination of completeness of surgical resection.

Survival Advantage Following TAG-72 Antigen-Directed Cancer Surgery in Patients With Colorectal Carcinoma: Proposed Mechanisms of Action.

Patients with colorectal carcinoma (CRC) continue to have variable clinical outcomes despite undergoing the same surgical procedure with curative intent and having the same pathologic and clinical stage. This problem suggests the need for better techniques to assess the extent of disease during surgery. We began to address this problem 35 years ago by injecting patients with either primary or recurrent CRC with 125I-labeled murine monoclonal antibodies against the tumor-associated glycoprotein-72 (TAG-72) and using a handheld gamma-detecting probe (HGDP) for intraoperative detection and removal of radioactive, i.e., TAG-72-positive, tissue. Data from these studies demonstrated a significant difference in overall survival data (p < 0.005 or better) when no TAG-72-positive tissue remained compared to when TAG-72-positive tissue remained at the completion of surgery. Recent publications indicate that aberrant glycosylation of mucins and their critical role in suppressing tumor-associated immune response help to explain the cellular mechanisms underlying our results. We propose that monoclonal antibodies to TAG-72 recognize and bind to antigenic epitopes on mucins that suppress the tumor-associated immune response in both the tumor and tumor-draining lymph nodes. Complete surgical removal of all TAG-72-positive tissue serves to reverse the escape phase of immunoediting, allowing a resetting of this response that leads to improved overall survival of the patients with either primary or recurrent CRC. Thus, the status of TAG-72 positivity after resection has a significant impact on patient survival.

124I-HuCC49deltaCH2 for TAG-72 antigen-directed positron emission tomography (PET) imaging of LS174T colon adenocarcinoma tumor implants in xenograft mice: preliminary results.

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.

Fabrication of indocyanine green encapsulated biodegradable microbubbles for structural and functional imaging of cancer.

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.

A comprehensive overview of radioguided surgery using gamma detection probe technology.

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.