EMI-137

Patients undergoing prophylactic central compartment dissection (PCLND) for papillary thyroid cancer (PTC) are often overtreated. This study aimed to determine if molecular fluorescence-guided imaging (MFGI) and spectroscopy can be useful for detecting PTC nodal metastases (NM) and to identify negative central compartments intraoperatively.

We used a data-driven prioritization strategy based on transcriptomic profiles of 97 primary PTCs and 80 normal thyroid tissues (NTT) to identify tumor-specific antigens for a clinically available near-infrared fluorescent tracer. Protein expression of the top prioritized antigen was immunohistochemically validated with a tissue microarray containing primary PTC (n = 741) and NTT (n = 108). Staining intensity was correlated with 10-year locoregional recurrence-free survival (LRFS). A phase 1 study (NCT03470259) with EMI-137, targeting MET, was conducted to evaluate safety, optimal dosage for detecting PTC NM with MFGI, feasibility of NM detection with quantitative fiber-optic spectroscopy, and selective binding of EMI-137 for MET.

MET was selected as the most promising antigen. A worse LRFS was observed in patients with positive versus negative MET staining (81.9% versus 93.2%; p = 0.02). In 19 patients, no adverse events related to EMI-137 occurred. 0.13 mg/kg EMI-137 was selected as optimal dosage for differentiating NM from normal lymph nodes using MFGI (p < 0.0001) and spectroscopy (p < 0.0001). MFGI identified 5/19 levels (26.3%) without NM. EMI-137 binds selectively to MET.

MET is overexpressed in PTC and associated with increased locoregional recurrence rates. Perioperative administration of EMI-137 is safe and facilitates NM detection using MFGI and spectroscopy, potentially reducing the number of negative PCLNDs with more than 25%.

NCT03470259.

The c-Met protein is overexpressed in many gastrointestinal cancers. We explored EMI-137, a novel c-Met targeting fluorescent probe, for application in fluorescence-guided colon surgery, in HT-29 colorectal cancer (CRC) cell line and an in vivo murine model.

HT-29 SiRNA transfection confirmed specificity of EMI-137 for c-Met. A HT-29 CRC xenograft model was developed in BALB/c mice, EMI-137 was injected and biodistribution analysed through in vivo fluorescent imaging. Nine patients, received a single intravenous EMI-137 bolus (0.13 mg/kg), 1-3 h before laparoscopic-assisted colon cancer surgery (NCT03360461). Tumour and LN fluorescence was assessed intraoperatively and correlated with c-Met expression in eight samples by immunohistochemistry.

c-Met expression HT-29 cells was silenced and imaged with EMI-137. Strong EMI-137 uptake in tumour xenografts was observed up to 6 h post-administration. At clinical trial, no serious adverse events related to EMI-137 were reported. Marked background fluorescence was observed in all participants, 4/9 showed increased tumour fluorescence over background; 5/9 had histological LN metastases; no fluorescent LN were detected intraoperatively. All primary tumours (8/8) and malignant LN (15/15) exhibited high c-Met protein expression.

EMI-137, binds specifically to the human c-Met protein, is safe, and with further refinement, shows potential for application in fluorescence-guided surgery.