Targeted detection of cancer at the cellular level during biopsy by near-infrared confocal laser endomicroscopy

A Phase 2 Multicenter Clinical Trial of Intraoperative Molecular Imaging of Lung Cancer with a pH-Activatable Nanoprobe

PURPOSE

Intraoperative molecular imaging (IMI) uses tumor-targeted optical contrast agents to improve identification and clearance of cancer. Recently, a probe has been developed that only fluoresces when activated in an acidic pH, which is common to many malignancies. We report the first multicenter Phase 2 trial of a pH-activatable nanoprobe (pegsitacianine, ONM-100) for IMI of lung cancer.

METHODS

Patients with suspected or biopsy-confirmed lung cancer scheduled for sublobar resection were administered a single intravenous infusion of pegsitacianine (1 mg/kg) one to three days prior to surgery. Intraoperatively, the patients underwent a white light thoracoscopic evaluation, and then were imaged with an NIR thoracoscope to detect tumor fluorescence. The primary study endpoint was the proportion of patients with a clinically significant event (CSE) which was defined as an intraoperative discovery during IMI that led to a change in the surgical procedure. Possible CSEs included (i) localizing the index lung nodule that could not be located by white light, (ii) identifying a synchronous malignant lesion, or (iii) recognizing a close surgical margin (< = 10 mm). Secondary endpoints were sensitivity, specificity, NPV, and PPV of pegsitacianine in detecting tumor-containing tissue. The safety evaluation was based on adverse event reporting, clinical laboratory parameters, and physical examinations.

RESULTS

Twenty patients were confirmed as eligible and administered pegsitacianine. Most of the patients were female (n = 12 [60%]), middle-aged (mean age 63.4 years), and former smokers (n = 13 [65%], 28.6 mean pack years). Mean lesion size was 1.9 cm, and most lesions (n = 17 [85%]) were malignant. The most common histologic subtype was adenocarcinoma (n = 9). By utilizing IMI with pegsitacianine, one patient had a CSE in the detection of a close margin and another had localization of a tumor not detectable by traditional surgical means. Six of 19 (31.6%) malignant lesions fluoresced with mean tumor-to-background ratio (TBR) of 3.00, as compared to TBR of 1.20 for benign lesions (n = 3). Sensitivity and specificity of pegsitacianine-based IMI for detecting malignant tissue was 31.6% and 33.3%, respectively. Positive predictive value (PPV) and negative predictive value (NPV) of pegsitacianine-based IMI was 75% and 7.1%, respectively. Pegsitacianine-based imaging was not effective in differentiating benign and malignant lymph nodes. From a safety perspective, no drug-related serious adverse events occurred. Four patients experienced mild pegsitacianine-related infusion reactions which required discontinuing the study drug with complete resolution of symptoms.

CONCLUSIONS

Pegsitacianine-based IMI, though well tolerated from a safety perspective, does not consistently label lung tumors during resection and does not provide significant clinical benefit over existing standards of surgical care. The biology of lung tumors may not be as acidic as other solid tumors in the body thereby not activating the probe as predicted.

Polarimetric imaging-based cancer bladder tissue's detection: A comparative study of bulk and formalin-fixed paraffin-embedded samples

The polarimetry imaging technique as a promising technique for pathological diagnosis provides a handy tool for identifying and discriminating cancerous tissues. In this paper, the optical polarization properties of bulk bladder tissues without any further processing and Formalin-Fixed Paraffin-Embedded (FFPE) blocks of bladder tissues have been measured. The images of the Muller matrix for both normal and cancerous samples have been obtained and for quantitative analysis and to provide a more precise comparison, two methods have been applied; the Mueller matrix polar decomposition (MMPD), and the Mueller matrix transformation (MMT). The results have shown that some of the extracted parameters from these methods can be used to identify the microstructural differentiations between normal and cancerous tissues. The results revealed a good accord between the obtained optical parameters for bulk and FFPE bladder tissues. By measuring the polarimetric properties of the tissue right after resection, and also in the early stages of pathology (FFPE tissues), this method can be applied in vivo to perform an optical biopsy; Furthermore, this method has the potential to significantly shortens the duration of pathological diagnosis. The approach seems remarkable, simple, precise, and economical compared to the existing techniques for the detection of cancerous samples.

A pH-Activatable Nanoprobe Labels Diverse Histologic Subtypes of Human Lung Cancer During Resection

BACKGROUND

Intraoperative molecular imaging (IMI) uses tumor-targeted optical contrast agents to improve identification and clearance of cancer during surgery. Recently, pH-activatable contrast agents have been developed but none has been tested in lung cancer. Here, we report the successful clinical translation of pegsitacianine (ONM-100), a pH-activatable nanoprobe, for fluorescence-guided lung cancer resection.

METHODS

We first characterized the pH setpoint for pegsitacianine fluorescence activation in vitro. We then optimized the specificity, dosing, and timing of pegsitacianine in murine flank xenograft models of lung adenocarcinoma and squamous cell carcinoma. Finally, we tested pegsitacianine in humans undergoing lung cancer surgery as part of an ongoing phase 2 trial.

RESULTS

We found that the fluorescence activation of pegsitacianine occurred below physiologic pH in vitro. Using preclinical models of lung cancer, we found that the probe selectively labeled both adenocarcinoma and squamous cell carcinoma xenografts (mean tumor-to-background ratio [TBR] > 2.0 for all cell lines). In the human pilot study, we report cases in which pegsitacianine localized pulmonary adenocarcinoma and pulmonary squamous cell carcinoma (TBRs= 2.7 and 2.4) in real time to illustrate its successful clinical translation and potential to improve surgical management.

CONCLUSIONS

This translational study demonstrates the feasibility of pegsitacianine as an IMI probe to label the two most common histologic subtypes of human lung cancer.

Single-institution experience of 500 pulmonary resections guided by intraoperative molecular imaging

OBJECTIVE

Intraoperative molecular imaging (IMI) using tumor-targeted optical contrast agents can improve thoracic cancer resections. There are no large-scale studies to guide surgeons in patient selection or imaging agent choice. Here, we report our institutional experience with IMI for lung and pleural tumor resection in 500 patients over a decade.

METHODS

Between December 2011 and November 2021, patients with lung or pleural nodules undergoing resection were preoperatively infused with 1 of 4 optical contrast tracers: EC17, TumorGlow, pafolacianine, or SGM-101. Then, during resection, IMI was used to identify pulmonary nodules, confirm margins, and identify synchronous lesions. We retrospectively reviewed patient demographic data, lesion diagnoses, and IMI tumor-to-background ratios (TBRs).

RESULTS

Five hundred patients underwent resection of 677 lesions. We found that there were 4 types of clinical utility of IMI: detection of positive margins (n = 32, 6.4% of patients), identification of residual disease after resection (n = 37, 7.4%), detection of synchronous cancers not predicted on preoperative imaging (n = 26, 5.2%), and minimally invasive localization of nonpalpable lesions (n = 101 lesions, 14.9%). Pafolacianine was most effective for adenocarcinoma-spectrum malignancies (mean TBR, 2.84), and TumorGlow was most effective for metastatic disease and mesothelioma (TBR, 3.1). False-negative fluorescence was primarily seen in mucinous adenocarcinomas (mean TBR, 1.8), heavy smokers (>30 pack years; TBR, 1.9), and tumors greater than 2.0 cm from the pleural surface (TBR, 1.3).

CONCLUSIONS

IMI may be effective in improving resection of lung and pleural tumors. The choice of IMI tracer should vary by the surgical indication and the primary clinical challenge.

Advances in bronchoscopic optical coherence tomography and confocal laser endomicroscopy in pulmonary diseases

PURPOSE OF REVIEW

Imaging techniques play a crucial role in the diagnostic work-up of pulmonary diseases but generally lack detailed information on a microscopic level. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are imaging techniques which provide microscopic images in vivo during bronchoscopy. The purpose of this review is to describe recent advancements in the use of bronchoscopic OCT- and CLE-imaging in pulmonary medicine.

RECENT FINDINGS

In recent years, OCT- and CLE-imaging have been evaluated in a wide variety of pulmonary diseases and demonstrated to be complementary to bronchoscopy for real-time, near-histological imaging. Several pulmonary compartments were visualized and characteristic patterns for disease were identified. In thoracic malignancy, OCT- and CLE-imaging can provide characterization of malignant tissue with the ability to identify the optimal sampling area. In interstitial lung disease (ILD), fibrotic patterns were detected by both (PS-) OCT and CLE, complementary to current HRCT-imaging. For obstructive lung diseases, (PS-) OCT enables to detect airway wall structures and remodelling, including changes in the airway smooth muscle and extracellular matrix.

SUMMARY

Bronchoscopic OCT- and CLE-imaging allow high resolution imaging of airways, lung parenchyma, pleura, lung tumours and mediastinal lymph nodes. Although investigational at the moment, promising clinical applications are on the horizon.

Comparative Experience of Short-wavelength Versus Long-wavelength Fluorophores for Intraoperative Molecular Imaging of Lung Cancer

BACKGROUND

Intraoperative molecular imaging (IMI) using tumor-targeted optical contrast agents can improve cancer resections. The optimal wavelength of the IMI tracer fluorophore has never been studied in humans and has major implications for the field. To address this question, we investigated 2 spectroscopically distinct fluorophores conjugated to the same targeting ligand.

METHODS

Between December 2011 and November 2021, patients with primary lung cancer were preoperatively infused with 1 of 2 folate receptor-targeted contrast tracers: a short-wavelength folate-fluorescein (EC17; λ em =520 nm) or a long-wavelength folate-S0456 (pafolacianine; λ em =793 nm). During resection, IMI was utilized to identify pulmonary nodules and confirm margins. Demographic data, lesion diagnoses, and fluorescence data were collected prospectively.

RESULTS

Two hundred eighty-two patients underwent resection of primary lung cancers with either folate-fluorescein (n=71, 25.2%) or pafolacianine (n=211, 74.8%). Most tumors (n=208, 73.8%) were invasive adenocarcinomas. We identified 2 clinical applications of IMI: localization of nonpalpable lesions (n=39 lesions, 13.8%) and detection of positive margins (n=11, 3.9%). In each application, the long-wavelength tracer was superior to the short-wavelength tracer regarding depth of penetration, signal-to-background ratio, and frequency of event. Pafolacianine was more effective for detecting subpleural lesions (mean signal-to-background ratio=2.71 vs 1.73 for folate-fluorescein, P <0.0001). Limit of signal detection was 1.8 cm from the pleural surface for pafolacianine and 0.3 cm for folate-fluorescein.

CONCLUSIONS

Long-wavelength near-infrared fluorophores are superior to short-wavelength IMI fluorophores in human tissues. Therefore, future efforts in all human cancers should likely focus on long-wavelength agents.

Endorectal Ultrasound Shear-Wave Elastography of Complex Rectal Adenoma and Early Rectal Cancer

Purpose: To investigate the diagnostic performance of endorectal ultrasound (ERUS), shear-wave elastography (SWE), and magnetic resonance imaging (MRI) in patients with a complex rectal adenoma or an early rectal cancer, i.e., T1 or T2 adenocarcinoma in a clinical setting, and to evaluate the association between SWE and stromal fraction (SF) and apparent diffusion coefficient (ADC) and SF. Method: This prospective study included patients undergoing ERUS and SWE for a rectal tumor subsequently confirmed by histopathology to be an adenoma or a T1 or T2 adenocarcinoma. The accuracy of the imaging methods was assessed by comparing the T category as determined by ERUS and MRI with histopathology, which served as the gold standard. SF was assessed on surgical specimens. Results: A total of 86 patients were included. Of these, 62 patients had adenomas and 24 patients had carcinomas, of which 11 were T1 tumors and 13 were T2 tumors. ERUS and MRI yielded sensitivity, specificity, and accuracy of 0.79 and 0.73, 0.95 and 0.90, and 0.86 and 0.78, respectively, for discrimination between benign and malignant lesions. The area under the receiver operating characteristics curve for SWE was 0.88, and with a cut-off value of 40 kPa the sensitivity, specificity, and accuracy were 0.79, 0.89, and 0.86, respectively. There was a positive correlation between SF and SWE with a p-value of <0.001 and a negative correlation between SF and ADC with a p-value of 0.011. Conclusion: Both ERUS and MRI classified T categories with a high accuracy; however, ERUS classified more adenomas correctly than MRI. In this small population, SWE could differentiate an adenoma from early carcinoma. SF was correlated with both SWE and ADC, as increasing SF tended to yield higher SWE and lower ADC values.

Preclinical Evaluation of an Activity-Based Probe for Intraoperative Imaging of Esophageal Cancer

Background

Early detection and complete resection are important prognostic factors for esophageal cancer (EC). Intraoperative molecular imaging (IMI) using tumor-targeted tracers is effective in many cancer types. However, there are no EC-specific IMI tracers. We sought to test a cathepsin activity-based tracer (VGT-309) for EC resection.

Methods

Murine (AKR, HNM007) and human (OE19) EC cell lines were screened for cathepsin expression by western blotting. In vitro binding affinity of VGT-309 was evaluated by fluorescence microscopy. Flank tumor models were developed by injecting EC cells into the flanks of BALB/c or athymic nude mice. Mice pretreated with a cathepsin inhibitor (JPM-OEt) were used to confirm on target binding. Animals were injected with 2 mg/kg VGT-309, underwent IMI, and were sacrificed 24 hours after injection.

Results

Cathepsins B, L, S, and X were expressed by EC cell lines, and all cell lines were labeled in vitro with VGT-309. Fluorescent signal was eliminated when cells were pretreated with JPM-OEt. On biodistribution analysis, VGT-309 accumulated in the liver, kidneys, and spleen without other organ involvement. VGT-309 selectively accumulated in flank allografts and xenografts, with mean signal-to-background ratio of 5.21 (IQR: 4.18-6.73) for flank allografts and 4.34 (IQR: 3.75-5.02) for flank xenografts. Fluorescence microscopy and histopathological analysis confirmed the selective accumulation of the tracer in tumors compared to background normal tissues.

Conclusions

VGT-309 is an effective tracer for IMI of esophageal cancer. There is potential for clinical translation both as an adjunct to endoscopic detection and for complete removal of disease during esophagectomy.