Onkar V. Khullar

Nerve-Highlighting Fluorescent Contrast Agents for Image-Guided Surgery

Nerve damage is the major morbidity of many surgeries, resulting in chronic pain, loss of function, or both. The sparing of nerves during surgical procedures is a vexing problem because surrounding tissue often obscures them. To date, systemically administered nerve-highlighting contrast agents that can be used for nerve-sparing image-guided surgery have not been reported. In the current study, physicochemical and optical properties of 4,4‘-[(2-methoxy-1,4-phenylene)di-(1E)-2,1-ethenediyl]bis-benzenamine (BMB) and a newly synthesized, red-shifted derivative 4-[(1E)-2-[4-[(1E)-2-[4-aminophenyl]ethenyl]-3-methoxyphenyl]ethenyl]-benzonitrile (GE3082) were characterized in vitro and in vivo. Both agents crossed the blood-nerve barrier and blood-brain barrier and rendered myelinated nerves fluorescent after a single systemic injection. Although both BMB and GE3082 also exhibited significant uptake in white adipose tissue, GE3082 underwent a hypsochromic shift in adipose tissue that provided a means to eliminate the unwanted signal using hyperspectral deconvolution. Dose and kinetic studies were performed in mice to determine the optimal dose and drug-imaging interval. The results were confirmed in rat and pig, with the latter used to demonstrate, for the first time, simultaneous fluorescence imaging of blood vessels and nerves during surgery using the FLARE™ (Fluorescence-Assisted Resection and Exploration) imaging system. These results lay the foundation for the development of ideal nerve-highlighting fluorophores for image-guided surgery.

Survival After Sublobar Resection versus Lobectomy for Clinical Stage IA Lung Cancer: An Analysis from the National Cancer Data Base

Background: Recent data have suggested possible oncologic equivalence of sublobar resection with lobectomy for early-stage non–small-cell lung cancer (NSCLC). Our aim was to evaluate and compare short-term and long-term survival for these surgical approaches. Methods: This retrospective cohort study utilized the National Cancer Data Base. Patients undergoing lobectomy, segmentectomy, or wedge resection for preoperative clinical T1A N0 NSCLC from 2003 to 2011 were identified. Overall survival (OS) and 30-day mortality were analyzed using multivariable Cox proportional hazards models, logistic regression models, and propensity score matching. Further analysis of survival stratified by tumor size, facility type, number of lymph nodes (LNs) examined, and surgical margins was performed. Results: A total of 13,606 patients were identified. After propensity score matching, 987 patients remained in each group. Both segmentectomy and wedge resection were associated with significantly worse OS when compared with lobectomy (hazard ratio: 1.70 and 1.45, respectively, both p < 0.001), with no difference in 30-day mortality. Median OS for lobectomy, segmentectomy, and wedge resection were 100, 74, and 68 months, respectively (p < 0.001). Finally, sublobar resection was associated with increased likelihood of positive surgical margins, lower likelihood of having more than three LNs examined, and significantly lower rates of nodal upstaging. Conclusion: In this large national-level, clinically diverse sample of clinical T1A NSCLC patients, wedge and segmental resections were shown to have significantly worse OS compared with lobectomy. Further patients undergoing sublobar resection were more likely to have inadequate lymphadenectomy and positive margins. Ongoing prospective study taking into account LN upstaging and margin status is still needed.

Image-Guided Sentinel Lymph Node Mapping and Nanotechnology-Based Nodal Treatment in Lung Cancer using Invisible Near-Infrared Fluorescent Light

Current methods for sentinel lymph node (SLN) mapping and nodal treatment in lung cancer remain inadequate for routine clinical use. In this study, we discuss the potential for using the combination of invisible near-infrared (NIR) fluorescent light and nanotechnology for these applications. NIR fluorescence imaging has recently received significant attention for in vivo imaging applications because of its low tissue autofluorescence, high photon penetration into living tissue, and high signal-to-background ratio. Our large animal in vivo studies have been able to successfully identify SLNs in lung tissue, and several clinical studies have examined the use of NIR fluorescence imaging systems for SLN mapping in breast and gastric cancer. Promising new nanoparticle technologies, when combined with NIR fluorescence imaging, offer the potential for image-guided treatment of lymph nodes at high risk for tumor recurrence. This review provides a theoretic and empiric framework for developing the next generation of diagnostic and therapeutic agents for lung cancer.

Identification of metastatic nodal disease in a phase 1 dose-escalation trial of intraoperative sentinel lymph node mapping in non–small cell lung cancer using near-infrared imaging

OBJECTIVES Early-stage non-small cell lung cancer (NSCLC) has a high recurrence rate and poor 5-year survival, particularly if lymph nodes are involved. Our objective was to perform a dose-escalation study to assess safety and feasibility of intraoperative near-infrared (NIR) fluorescence imaging to identify the first tumor-draining lymph nodes (ie, sentinel lymph nodes [SLNs] in patients with NSCLC). METHODS A-dose escalation phase 1 clinical trial assessing real-time NIR imaging after peritumoral injection of 3.8 to 2500 μg indocyanine green (ICG) was initiated in patients with suspected stage I/II NSCLC. Visualization of lymphatic migration, SLN identification, and adverse events were recorded. RESULTS Thirty-eight patients underwent ICG injection and NIR imaging via thoracotomy (n = 18) or thoracoscopic imaging (n = 20). SLN identification increased with ICG dose, with fewer than 25% SLNs detected in dose cohorts of 600 μg or less versus 89% success at 1000 μg or greater. Twenty-six NIR(+) SLNs were identified in 15 patients, with 7 NIR(+) SLNs (6 patients) harboring metastatic disease on histologic analysis. Metastatic nodal disease was never identified in patients with a histologically negative NIR(+) SLN. No adverse reactions were noted. CONCLUSIONS NIR-guided SLN identification with ICG was safe and feasible in this initial dose-escalation trial. ICG doses greater than 1000 μg yielded nearly 90% intrathoracic SLN visualization, with the presence or absence of metastatic disease in the SLN directly correlating with final nodal status of the lymphadenectomy specimen. Further studies are needed to optimize imaging parameters and confirm sensitivity and specificity of SLN mapping in NSCLC using this promising imaging technique.

Nanoparticle migration and delivery of Paclitaxel to regional lymph nodes in a large animal model.

BACKGROUND The aim of this study was to demonstrate feasibility of migration and in situ chemotherapy delivery to regional lymph nodes (LN) in a large animal model using an expansile polymer nanoparticle (eNP) delivery system. STUDY DESIGN Dual-labeled 50-nm and 100-nm eNP were prepared by encapsulating an IR-813 near-infrared (NIR) fluorescent dye within coumarin-conjugated expansile polymer nanoparticles (NIR-C-eNP). NIR imaging and fluorescent microscopy were used to identify intralymphatic migration of NIR-nanoparticles to draining inguinal or mesenteric LN after injection in swine hind legs or intestine. Nanoparticle-mediated intranodal delivery of chemotherapy was subsequently assessed with Oregon Green paclitaxel-loaded NIR-eNP (NIR-OGpax-eNP). RESULTS NIR imaging demonstrated direct lymphatic migration of 50-nm, but not 100-nm, NIR-C-eNP and NIR-OGpax-eNP to the draining regional LNs after intradermal injection in the hind leg or subserosal injection in intestine. Fluorescent microscopy demonstrated that IR-813 used for NIR real-time trafficking colocalized with both the coumarin-labeled polymer and paclitaxel chemotherapy and was identified within the subcapsular spaces of the draining LNs. These studies verify nodal migration of both nanoparticle and encapsulated payload, and confirm the feasibility of focusing chemotherapy delivery directly to regional nodes. CONCLUSIONS Regionally-targeted intranodal chemotherapy can be delivered to draining LNs for both skin and solid organs using 50-nm paclitaxel-loaded eNP.

Paclitaxel-Loaded Expansile Nanoparticles Delay Local Recurrence in a Heterotopic Murine Non-Small Cell Lung Cancer Model

BACKGROUND Surgical resection remains the most effective treatment option for patients with early stage non-small cell lung cancer; however, comorbidities and poor pulmonary reserve often limit the extent of resection. Limited resections are associated with a twofold to threefold increase in locoregional recurrence, suggesting that microscopic disease remains near the resection margin. We hypothesized that local delivery of paclitaxel through 100-nm expansile polymer nanoparticles (pax-eNP) immediately after tumor resection could prevent local recurrence. METHODS Primary tumors, initiated on the dorsum of C57BL/6J mice through subcutaneous injection of 750,000 Lewis lung carcinoma cells, were excised when tumor volume reached 300 mm(3). After resection, animals were randomized to receive 300 μg paclitaxel intravenously or as pax-eNP locally at the tumor resection site versus unloaded eNP or saline controls. RESULTS In all mice receiving saline, unloaded eNP, or paclitaxel intravenously, visible local tumor recurrence developed at a median of 6 days. In contrast, tumor recurrence after pax-eNP was delayed to 10 days (pax-eNP versus all other groups, Kaplan-Meier, p < 0.05). Delay in local recurrence was associated with increased survival in the pax-eNP group (16 days) versus all other groups (11 and 12 days, p < 0.05). CONCLUSIONS The pax-eNP placed at the time of surgical resection delayed local tumor recurrence and modestly prolonged survival in a murine Lewis lung carcinoma recurrence model.

Ease of Synthesis, Controllable Sizes, and In Vivo Large Animal Lymph Migration of Polymeric Nanoparticles

Polymeric nanoparticles were synthesized using both a photoinduced and base-catalyzed free radical polymerization method. These mild room temperature approaches allow sensitive molecules, such as dyes, to be encapsulated. Using this method, near infrared dye loaded nanoparticles for lymphatic migration and lymph nodes localization were synthesized. After injection into a large animal, we observed migration of the nanoparticles over 20 cm to the sentinel lymph. Nanoparticle migration was observed for nanoparticles of 50 nm but not 100 nm in diameter. These investigations further support the development of new materials and clinical approaches to treat cancer including identification of nodal disease, characterization of the extent of disease, and establishment of treatment regimes.

Socioeconomic Risk Factors for Long-Term Mortality after Pulmonary Resection for Lung Cancer: An Analysis of More than 90,000 Patients from the National Cancer Data Base

BACKGROUND Several clinical variables, such as tumor stage and age, are well established factors associated with long-term survival after surgical resection of lung cancer. Our aim was to examine the impact of other clinical and demographic variables, controlling for known predictors of long-term survival, in order to investigate how outcomes varied according to important nonclinical factors. STUDY DESIGN The National Cancer Data Base, jointly supported by the Commission on Cancer of the American College of Surgeons and the American Cancer Society, was used to identify patients undergoing pulmonary resection for lung cancer and perform a retrospective cohort study. The cohort consisted of patients diagnosed with nonsmall cell lung cancer from 2003 to 2006, who underwent resection; overall survival data are available only for patients diagnosed through 2006. A Cox proportional hazards survival model was used to examine factors associated with risk of mortality. RESULTS A total of 92,929 patients were identified as diagnosed during the study period and undergoing surgical resection for lung cancer. On multivariable analysis, several socioeconomic factors such as lack of insurance, lower income, less education, and treatment at community centers vs academic or research programs predicted worse overall survival after controlling for disease characteristics known to be predictors of worse survival, such as tumor stage, histology, age, and extent of resection. CONCLUSIONS Diminished long-term survival after pulmonary resection was associated with a number of socioeconomic factors. To date, this represents the largest database analysis of long-term mortality in patients undergoing surgical resection for lung cancer. The disparities in survival outcomes reported here require further detailed investigation.

Hospital Readmission Is Associated With Poor Survival After Esophagectomy for Esophageal Cancer

BACKGROUND Hospital readmissions are costly and associated with inferior patient outcomes. There is limited knowledge related to readmissions after esophagectomy for malignancy. Our aim was to determine the impact on survival of readmission after esophagectomy. METHODS This cohort study utilizes Surveillance, Epidemiology, and End Results-Medicare data (2002 to 2009). Survival, length of stay, 30-day readmissions, and discharge disposition were determined. Multivariate logistic regression models were created to examine risk factors associated with readmission. RESULTS In all, 1,744 patients with esophageal cancer underwent esophagectomy: 80% of patients (1,390) were male, and mean age was 73 years; 71.8% of tumors (1,251) were adenocarcinomas, and 72.5% (1,265) were distal esophageal tumors; 38% of patients (667) received induction therapy. Operative approach was transthoracic in 52.6% of patients (918) and transhiatal in 37.4% (653), and required complex reconstruction (intestinal interposition) in 9.9% (173). Stage distribution was as follows: stage I, 35.3% (616); stage II, 32.5% (566); stage III, 27.9% (487); and stage IV, 2.3% (40). Median length of stay was 13 days, hospital mortality was 9.3% (158 patients), and 30-day readmission rate was 18.6% (212 of 1,139 home discharges); 25.4% of patients (443) were discharged to institutional care facilities. Overall survival was significantly worse for patients who were readmitted (p < 0.0001, log rank test). Risk factors for readmission were comorbidity score of 3+, urgent admission, and urban residence. CONCLUSIONS Hospital readmissions after esophagectomy for cancer occur frequently and are associated with worse survival. Improved identification of patients at risk for readmission after esophagectomy can inform patient selection, discharge planning, and outpatient monitoring. Optimization of such practices may lead to improved outcomes at reduced cost.

A novel technique for tumor localization and targeted lymphatic mapping in early-stage lung cancer

Objective: To investigate safety and feasibility of navigational bronchoscopy (NB)‐guided near‐infrared (NIR) localization of small, ill‐defined lung lesions and sentinel lymph nodes (SLN) for accurate staging in patients with non–small cell lung cancer (NSCLC). Methods: Patients with known or suspected stage I NSCLC were enrolled in a prospective pilot trial for lesion localization and SLN mapping via NB‐guided NIR marking. Successful localization, SLN detection rates, histopathologic status of SLN versus overall nodes, and concordance to initial clinical stage were measured. Ex vivo confirmation of NIR+ SLNs and adverse events were recorded. Results: Twelve patients underwent NB‐guided marking with indocyanine green of lung lesions ranging in size from 0.4 to 2.2 cm and located 0.1 to 3 cm from the pleural surface. An NIR+ “tattoo” was identified in all cases. Ten patients were diagnosed with NSCLC and 9 SLNs were identified in 8 of the 10 patients, resulting in an 80% SLN detection rate. SLN pathologic status was 100% sensitive and specific for overall nodal status with no false‐negative results. Despite previous nodal sampling, one patient was found to have metastatic disease in the SLN alone, a 12.5% rate of disease upstaging with NIR SLN mapping. SLN were detectable for up to 3 hours, allowing time for obtaining a tissue diagnosis and surgical resection. There were no adverse events associated with NB‐labeling or indocyanine green dye itself. Conclusions: NB‐guided NIR lesion localization and SLN identification was safe and feasible. This minimally invasive image‐guided technique may permit the accurate localization and nodal staging of early stage lung cancers.