Detection of thyroid cancer and central lymph node metastases using bevacizumab-IRDye800CW enhanced Molecular Fluorescence Guided Surgery

Almost 50 % of papillary thyroid cancer (PTC) patients have central lymph node
metastases (CLNM), which are associated with a high risk of persistent or
recurrent disease. Approximately 5-20% of patients eventually develop
loco-regional recurrent disease. However, the practice of performing a
prophylactic central lymph node dissection (PCLND) routinely remains
controversial. The proponents argue that without a PCLND, PTC patients with
positive lymph nodes have an increased risk of local recurrence, and postponed
node dissection leads to with 5-6 fold higher risk of morbidity. If performed,
PCLND in clinical node negative patients increases staging to pN1 in more than
50% of the cases without increasing survival. To prevent one reoperation, 20
PCLNDs are needed. The complication rate (permanent hypoparathyroidism and
recurrent nerve damage) in PCLND is lower when compared to a technically
challenging re-exploration in recurrent disease, with reported incidences of
0.6% and 7.3-20%, respectively. Opponents of routine PCLND point out the lack
of randomized clinical trials and object to treatment-induced
hypoparathyroidism and recurrent nerve damage for the N0 patients. The national
protocol in the Netherlands advises based on a very low grade of evidence to
perform a CLND in case of males aged over 45 years, large or multifocal
tumours, or extra capsular growth. Currently, no diagnostic tool is available
which reliably identifies these patient categories. Therefore, there is a clear
need for novel diagnostic imaging modalities that overcome this issue.
Molecular Fluorescence Guided Surgery (MFGS) is potentially such a diagnostic
tool. The administration of NIR fluorescent tracers can increase detection
accuracy of cancer and nodal metastatic tissue using macroscopic MFGS.
Therefore, we aimed to identify a GMP-produced near infrared (NIR) tracer that
potentially has a high target-to-background ratio in PTC compared to normal
thyroid tissue. VEGF-A is significantly upregulated at the protein level in PTC
compared to normal thyroid tissue. Research showed that VEGF-a is also
upregulated in Follicular thyroid carcinoma (FTC), in Hürtle cell carcinoma
(HTC) and in Poorly differentiated thyroid carcinoma (PDTC). Clinicians
experience the same problem detecting lymph node metastasis in FTC/HTC/PDTC as
in PTC. We therefore hypothesize that the GMP-produced NIR-fluorescent tracer
bevacizumab-IRDye800CW (targeting VEGF-A, peak emission at 774 nm/789 nm range)
might be useful for intraoperative imaging of PTC/FTC/HTC/PDTC and nodal
metastases. Our aim is to investigate if the administration of
bevacizumab-IRDye800CW is a feasible approach to enable intraoperative
selection of PTC/FTC/HTC/PDTC patients for CLND. Eventually, secondary we might
also be able to visualize multifocality, more selective lateral neck
dissections and asses residual tissue after thyroidectomy. Ultimately, all of
these strategies may reduce overtreatment, morbidity, and costs while
maintaining the same or better effectiveness with a lower recurrence rate and
improved quality of life.

Primary Objectives
- To determine the optimal dose of the VEGF-A targeting NIRF tracer
bevacizumab-IRDye800CW for an adequate tumor-to-background ratio (TBR) in
PTC/FTC/HTC/PDTC lymph node metastases.

Secondary Objectives
- To evaluate the feasibility of MFGS for the assessment of PTC/FTC/HTC/PDTC
and nodal metastasis.
- To correlate and validate fluorescence signals detected in vivo with ex vivo
histopathology and immunohistochemistry.
- To evaluate the distribution of bevacizumab-IRDye800CW on a microscopic level.
- To quantify sensitivity and specificity of bevacizumab-IRDye800CW for
PTC/FTC/HTC/PDTC and nodal metastasis in order to make a power size calculation
for a possible subsequent diagnostic accuracy study

The TARGET-BEVA study is a non-randomized, non-blinded, prospective, single
center phase I feasibility study for patients with TxNxM0 confirmed
PTC/FTC/HTC/PDTC, for which we will determine the dosage group with the best
TBR in PTC/FTC/HTC/PDTC nodal metastasis. We will initiate the phase I study
with a 2 x 3 scheme: 10 mg (n=3 with confirmed lymph node metastasis), and 25
mg (n=3 with confirmed lymph node metastasis). We will start with a dosage
group of 10 mg, and increase to a dosage of 25 mg. Dosages are based on data
from previous studies performed in our center showing that the administration
of these doses in patients with solid tumors is safe and provides a good TBR.
As the primary objective is the detection of lymph node metastasis, we will
perform a dose finding study and will only proceed to the next dosage group if
we can determine a TBR in three patients. The reasoning for this approach is
the low sensitivity of preoperative imaging for lymph node metastasis.
Metastasis can only be confirmed after histopathological examination. Following
completion of the dosage groups an interim analysis will be performed to assess
the dosage that will provide the optimal TBR in nodal metastasis. We will
analyze the TBR for each dosing group. The TBR will be calculated as follows:
TBR = (tumor fluorescence)/(surrounding tissue fluorescence). If both dosage
cohort provide the same excellent TBR, we will deescalate to a dosage of 4.5 mg
(n=3 with confirmed lymph node metastasis) to evaluate TBR and reduce possible
tracer toxicity. Finally, for the dosage cohort with the most optimal TBR we
will expand this group to a total of ten patients to have a minimal significant
data set which will serve for a subsequent accuracy study. Should the safety
profile or dosage in terms of optimal TBR not be sufficient, we abandon the
tested tracer.

Tracer administration: Bevacizumab-800CW is administered via an IV 2 days
before surgery and patients are monitored for any
to be able to observe side effects. Dosages of 4.5 / 10 / 25mg can be used in
this study.

Specimen-related study protocol: The excised tissue is examined
histopathologically according to current
protocols for clinical oncology care. Diagnosis, tumor size, multifocality,
margins and histological features
The pathologist reports on clinical decision-making. In addition, ex vivo is
taken outside of the operating room for
fluorescent imaging. This data is related to histopathological data
(H&E and additional immunohistochemical stains such as VEGF-A) and the
localization of the fluorescent lesions.

Patient and specimen related protocols
Tracer administration: Bevacizumab-IRDye800CW will be administered two days
prior to incision by infusion and/or bolus injection. Patients will be
monitored for 15 minutes for potential side effects. Dosages administered
throughout the study will be either 4.5 mg, 10 mg and 25 mg.
Perioperative imaging: The aim is to test the accuracy of
bevacizumab-IRDye800CW (TBR) to primary identify PTC/FTC/HTC/PDTC nodal
metastases. A multispectral Near Infrared Fluorescence (NIRF) camera system
sensitive for bevacizumab-IRDye800CW fluorescence will be used for
intraoperative imaging of the lymph node dissection. During the procedure, the
surgeon may take a maximum of ten additional biopsies from regions of interest
to acquire information about tracer accuracy (for example fluorescent positive
tissue macroscopically not suspect as malignant tissue or fluorescent negative
tissue that macroscopically is suspected to be malignant tissue). Finally, the
excised specimens will be imaged ex vivo to acquire additional information
about fluorescence distribution. This phase 1 study procedures will not
influence surgical decision making nor the extend of surgery. General clinical
practice will have priority over study procedures. Histopathological features
of all excised tissue will be assessed by a pathologist.
Specimen related study protocol: The excised specimens will undergo
histopathological assessment according to the current standard used in clinical
cancer care. Diagnosis, tumor size, multi-focality, margins and selected
histological features necessary for clinical decision making will be provided
by the pathologist. Next to this, ex vivo imaging will be performed on the
excised specimen and biopsies. In vivo and ex vivo images will be related to
histopathological data (H&E and additional immunohistochemical stainings such
as VEGF-A) and the location of the fluorescent lesions.