Inter-assay reliability of programmed cell death-ligand 1 in head and neck squamous cell carcinoma

OBJECTIVES

The programmed cell death-ligand 1 (PD-L1) 22C3 pharmDx assay is used as a companion diagnostic test to select head and neck squamous cell carcinoma (HNSCC) patients that may benefit from treatment with the checkpoint inhibitor pembrolizumab. Because the Dako platform is not universally available, we studied the performance of a 22C3 laboratory developed test (LDT) performed on a Ventana BenchMark Ultra compared to the 22C3 pharmDx assay.

MATERIALS AND METHODS

Serial sections from tissue micro arrays (TMAs) containing tumour tissue from 97 HNSCC patients were stained with the 22C3 pharmDx assay and 22C3 LDT. All TMA cores were scored by three dedicated head and neck pathologists for PD-L1 expression.

RESULTS

Substantial interobserver agreement was reported for both the standardized 22C3 pharmDx assay and the 22C3 LDT (respectively Fleiss' κ 0.62, 95% CI 0.57-0.67 and 0.63, 95% CI 0.58-0.68). Concordance between the assays was almost perfect on core and patient level (respectively Weighted κ 0.84, 95% CI 0.79-0.89 and 0.84, 95% CI 0.75-0.92). Intratumor heterogeneity between the cores per patient case was similar in both assays.

CONCLUSION

After validation a 22C3 LDT is non-inferior to the standardized 22C3 pharmDx assay and can be safely used to select HNSCC patients for pembrolizumab treatment.

[A large maxillary fibroepithelial polyp: a lump in the throat]

A 55-year-old woman was seen at an oral and maxillofacial surgery department because of a large oral swelling and complaints about difficulty eating, nasal speech and fatigue. She had full dentures in her upper jaw. Intraorally, a pain-free, pedunculated, combined solid-elastic and bone-hard tumour was found in the left maxillary tubercle region. A large, fibroepithelial polyp was diagnosed based on clinical and histopathological findings. Six weeks post-operatively, the complaints had disappeared. Chronic irritation of the oral mucosa can result in an oral fibroepithelial polyp that can be distinguished from peripheral ossifying fibroma or giant cell fibroma after histopathological examination. Such a polyp can grow to a large size if the source of irritation is not removed.

A Standardized Framework for Fluorescence-Guided Margin Assessment for Head and Neck Cancer Using a Tumor Acidosis Sensitive Optical Imaging Agent

Purpose

Intra-operative management of the surgical margin in patients diagnosed with head and neck squamous cell carcinoma (HNSCC) remains challenging as surgeons still have to rely on visual and tactile information. Fluorescence-guided surgery using tumor-specific imaging agents can assist in clinical decision-making. However, a standardized imaging methodology is lacking. In this study, we determined whether a standardized, specimen-driven, fluorescence imaging framework using ONM-100 could assist in clinical decision-making during surgery.

Procedures

Thirteen patients with histologically proven HNSCC were included in this clinical study and received ONM-100 24 ± 8 h before surgery. Fluorescence images of the excised surgical specimen and of the surgical cavity were analyzed. A fluorescent lesion with a tumor-to-background ratio (TBR) > 1.5 was considered fluorescence-positive and correlated to standard of care (SOC) histopathology.

Results

All six tumor-positive surgical margins were detected immediately after excision using fluorescence-guided intra-operative imaging. Postoperative analysis showed a median TBR (±IQR) of the fluorescent lesions on the resection margin of 3.36 ± 1.62. Three fluorescence-positive lesions in the surgical cavity were biopsied and showed occult carcinoma and severe dysplasia, and a false-positive fluorescence lesion.

Conclusion

Our specimen-driven fluorescence framework using a novel, pH-activatable, fluorescent imaging agent could assist in reliable and real-time adequate clinical decision-making showing that a fluorescent lesion on the surgical specimen with a TBR of 1.5 is correlated to a tumor-positive resection margin. The binary mechanism of ONM-100 allows for a sharp tumor delineation in all patients, giving the surgeon a clinical tool for real-time margin assessment, with a high sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11307-021-01614-z.

Exploiting metabolic acidosis in solid cancers using a tumor-agnostic pH-activatable nanoprobe for fluorescence-guided surgery

Cancer cell metabolism leads to a uniquely acidic microenvironment in solid tumors, but exploiting the labile extracellular pH differences between cancer and normal tissues for clinical use has been challenging. Here we describe the clinical translation of ONM-100, a nanoparticle-based fluorescent imaging agent. This is comprised of an ultra-pH sensitive amphiphilic polymer, conjugated with indocyanine green, which rapidly and irreversibly dissociates to fluoresce in the acidic extracellular tumor microenvironment due to the mechanism of nanoscale macromolecular cooperativity. Primary outcomes were safety, pharmacokinetics and imaging feasilibity of ONM-100. Secondary outcomes were to determine a range of safe doses of ONM-100 for intra-operative imaging using commonly used fluorescence camera systems. In this study (Netherlands National Trial Register #7085), we report that ONM-100 was well tolerated, and four solid tumor types could be visualized both in- and ex vivo in thirty subjects. ONM-100 enables detection of tumor-positive resection margins in 9/9 subjects and four additional otherwise missed occult lesions. Consequently, this pH-activatable optical imaging agent may be clinically beneficial in differentiating previously unexploitable narrow physiologic differences.

It is well known that the pH of tumor tissue is lower than that of the corresponding normal adjacent tissue. Here, the authors report a clinical trial of a pH activatable nanoparticle for imaging tumours.

Fluorescence-guided imaging for resection margin evaluation in head and neck cancer patients using cetuximab-800CW: A quantitative dose-escalation study

Tumor-positive resection margins are present in up to 23% of head and neck cancer (HNC) surgeries, as intraoperative techniques for real-time evaluation of the resection margins are lacking. In this study, we investigated the safety and potential clinical value of fluorescence-guided imaging (FGI) for resection margin evaluation in HNC patients. We determined the optimal cetuximab-800CW dose by quantification of intrinsic fluorescence values using multi-diameter single-fiber reflectance, single-fiber fluorescence (MDSFR/SFF) spectroscopy.

Methods: Five cohorts of three HNC patients received cetuximab-800CW systemically: three single dose cohorts (10, 25, 50 mg) and two cohorts pre-dosed with 75 mg unlabeled cetuximab (15 or 25 mg). Fluorescence visualization and MDSFR/SFF spectroscopy quantification was performed and were correlated to histopathology.

Results: There were no study-related adverse events higher than Common Terminology Criteria for Adverse Events grade-II. Quantification of intrinsic fluorescence values showed a dose-dependent increase in background fluorescence in the single dose cohorts (p<0.001, p<0.001), which remained consistently low in the pre-dosed cohorts (p=0.6808). Resection margin status was evaluated with a sensitivity of 100% (4/4 tumor-positive margins) and specificity of 91% (10/11 tumor-negative margins).

Conclusion: A pre-dose of 75 mg unlabeled cetuximab followed by 15 mg cetuximab-800CW was considered the optimal dose based on safety, fluorescence visualization and quantification of intrinsic fluorescence values. We were able to use a lower dose cetuximab-800CW than previously described, while remaining a high sensitivity for tumor detection due to application of equipment optimized for IRDye800CW detection, which was validated by quantification of intrinsic fluorescence values.

Image-guided surgery for tumor agnostic detection of solid tumors using the pH-activated micellar imaging agent ONM-100

3068

Background: ONM-100, a micelle-based polymer imaging agent conjugated to indocyanine green (ICG) and with an exquisitely pH-sensitive binary activation mechanism, may be used for tumor detection. ONM-100 micelles dissociate in acidic environments resulting in activation of the fluorescent ICG tag. As nearly all solid cancer types are acidotic, ONM-100 has the potential to act as a broadly indicated tumor agnostic imaging agent. This first-in-human study investigates the safety and feasibility of ONM-100 as a tumor agnostic imaging agent for intra-operative fluorescent imaging of various solid tumors. Methods: ONM-100 was IV administered 24±8h prior to surgery in a dose escalation scheme (0.1-1.2mg/kg). Patients with histopathologically confirmed breast cancer (BC), head and neck squamous cell carcinoma (HNSCC), colorectal cancer (CRC) and esophageal cancer (EC) were included. Blood was drawn to assess safety and pharmacokinetic data. Intra-operative fluorescence images were collected before and after tumor excision. Post-excision fluorescence images were obtained from serially sliced specimens and correlated with standard histopathological assessment. Results: 30 patients (11 BC, 13 HNSCC, 3 EC, 3 CRC) were enrolled. No ONM-100 related serious adverse events were observed and the agent was well-tolerated. A strong and sharply demarcated fluorescent signal was observed in all patients with vital tumor tissue (median CNR ranging 1.85-14.05) which correlated with tumor on final histopathology. HNSCC and superficially located BC as well as peritoneal metastasis could be clearly visualized in vivo during surgery. In four patients (BC and HNSCC), perioperatively, tumors otherwise unnoticed by the surgeons were detected on the margin or wound bed using fluorescence imaging. Additionally, two BC tumor lesions were detected that were missed by conventional pre-operative imaging and pathological assessment. Conclusions: ONM-100 appears to be safe and enables fluorescent visualization of tumors both in vivo and ex vivo. The first-in-human data demonstrate the feasibility for potential use of ONM-100 for image guided surgery, margin assessment and detection of occult disease. Clinical trial information: NTR 7085.

Abstract P2-14-29: Image guided surgery for tumor detection in breast cancer using the PH activated micellar tracer ONM-100: The SHINE study

Background: Currently, no reliable intra-operative tumor detection and margin assessment technologies during breast conserving surgery are available. Fluorescence-guided surgery (FGS) using tumor specific fluorescent tracers can improve intra-operative tumor detection. However, a major limitation is the lack of broad tumor applicability due to complex oncogenotypes and histologic phenotypes. A strategy to overcome this challenge is targeting metabolic vulnerabilities that are more ubiquitous and regarded as generic hallmarks of cancer. The extracellular environment of tumors is relatively acidic compared to healthy tissue due to aerobic glycolysis, the so-called Warburg effect. ONM-100, a micellar polymer tracer labeled with the fluorescent imaging dye Indocyanine Green (ICG), has an exquisitely pH-sensitive binary on/off mechanism. The micelles dissociate in acidic environments causing the unquenching and fluorescent activation of the ICG dye. As most solid cancer types are acidotic, ONM-100 acts as a generic tracer targeting a broad range of tumors. This proof of concept, first in-human study, investigates the safety and feasibility of ONM-100 as an intra-operative fluorescent tracer in breast cancer (BC) patients.

Methods: In this phase 1 study, the pH-activated fluorescent tracer ONM-100 was administered 24±8h prior to surgery in a dose escalation scheme ranging from 0.1 mg/kg to 0.8 mg/kg in groups of 3 patients each. Patients with biopsy proven BC were included. Patients that had undergone neoadjuvant therapy were excluded. Blood was drawn up to day 10 to assess safety and pharmacokinetic data. Intra-operative images were collected of the tumor before and after excision and of the wound bed. Immediately after excision ex vivo fluorescence images were obtained from the serially sliced specimen and the formalin fixated paraffin embedded tissue blocks. Fluorescence images were correlated with histopathological assessment on Hematoxylin and Eosin (H/E) stained sections.

Results: In this ongoing clinical trial, 4 patients with BC were enrolled between March and May 2018. No tracer related (serious) adverse events were observed. A strong and sharply demarcated fluorescent signal in tumor tissue was observed in all 4 patients with in- and ex vivo imaging (median Contrast to Noise Ratio 6.5; IQR 7.25), which correlated with areas of tumor involvement on histopathology. In one BC patient, an intra-operatively unnoticed tumor positive margin was detected using fluorescence imaging. Additionally, a BC satellite lesion was detected, which was otherwise missed by the pathologist.

Conclusion: Preliminary results of this ongoing first in-human study with the pH-activated tracer ONM-100 shows that ONM-100 is well tolerated and safe and allows fluorescent tumor visualization both in- and ex vivo. Here, we provide the first data that this pH-sensitive optical tracer can be used as a tracer for FGS and for margin detection. Further analysis on microscopic biodistribution of ONM-100 is currently being performed and possibilities for metastatic lymph node detection will be explored.

Citation Format: Steinkamp PJ, Voskuil FJ, Koller M, van der Vegt B, Doff JJ, Zhao T, Hartung J, Jayalakshmi Y, Sumer BD, Gao J, Witjes MJ, van Dam GM. Image guided surgery for tumor detection in breast cancer using the PH activated micellar tracer ONM-100: The SHINE study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-29.