Visualization of a VEGF-targeted Optical Fluorescent Imaging Tracer in rectal cancer during flexible Near-Infrared fluorescence endoscopy;A single center feasibility study

To improve rectal cancer management, there is a need for better visualization
of drug targets in rectal cancer to identify patients who might benefit from
specific targeted treatments. Molecular imaging of rectal cancer associated
targets is a promising technique to accommodate this need. Vascular Endothelial
Growth Factor (VEGF), which is differentially expressed in normal versus
malignant colon tissue, has proven to be a valid target for molecular imaging.
Fluorescent labeling of bevacizumab (a VEGF targeting humanized monoclonal
antibody currently used in anti-cancer therapy) has potential advantages in
view of safety, infrastructure, costs, stability and imaging resolution.
Therefore, the fluorescent tracer bevacizumab-IRDye800CW has been developed at
the University Medical Center Groningen (UMCG) and was recently approved to be
administered to patients in a tracer dose (NL37479.042.11). To detect this
tracer in vivo in patients with colorectal cancer, a newly developed flexible
near-infrared (NIR) fluorescence endoscope, MDSFR/SFF spectrofiber and
optoacoustic endoscope have been developed which can be used in clinical
studies. Optical fluorescence imaging may support response evaluation following
chemoradiotherapy and give insight which patient might benefit from anti-VEGF
targeted therapy in future studies. In addition, information collected in this
study regarding tracer distribution can be used for future studies in which
flexible NIR fluorescence endoscopy will be validated for detection of
premalignant lesions in the colon and oesophagus.

The primary objective of this study is to determine the sensitivity of the
marker bevacizumab-IRDye800CW using innovative NIR fluorescence endoscopy
(visualizing with wide-field endoscopy, measuring with MDSFR/SFF spectroscopy
and optionally visualizing with optoacoustic endoscopy), in identifying target
expression and heterogeneity prior to the start and after neoadjuvant
treatment.

The secondary objectives of this study are:
- Study if fluorescence endoscopy can evaluate treatment response after
neoadjuvant treatment, just prior to surgery.
- Study if there is a correlation between the outcome of fluorescence endoscopy
and other biological and molecular parameters.
- Study if there is a correlation between the outcome of fluorescence
endoscopy and circulating tumour DNA.

The current study is a non-randomized, non-blinded, prospective, single center
feasibility study to determine whether molecular imaging using NIR fluorescence
endoscopy and bevacizumab-IRDye800CW can provide insight into the heterogeneity
of the target VEGF in patients with locally advance rectum carcinoma, to
identify patients who might benefit from additional targeted anti-VEGF
treatment.

Patients with locally advanced rectum carcinoma are allowed to be included in
the RAPIDO study (NL36315.042.11). Subjects will undergo two times
epi-illumination endoscopy (in other words flexible NIR fluorescence
endoscopy). The first endoscopy will be performed at baseline; before the start
of chemoradiotherapy. The second endoscopy will be performed within 2 weeks
before surgery. The new VEGF-targeting fluorescent tracer
(bevacizumab-IRDye800CW) will be administered intravenously two days before the
flexible NIR fluorescence endoscopy procedure. During the flexible NIR
fluorescence endoscopy procedure we will determine whole tumor distribution of
bevacizumab-IRDye800CW to gain insight into tumor heterogeneity. Subsequently,
the NIR fluorescent signal in various areas of the lesion will be quantified.
Tumors will be imaged using different angles to get optimal excitation of the
tissue. We will measure the fluorescence using MDSFR/SFF spectroscopy. We will
take targeted biopsies from areas with high and low uptake of the tracer during
epi-illumination endoscopy for ex vivo analyses (at least 4 reproducible small
biopsies per area to decrease sampling error; 2 for paraffin embedding and 2
for frozen collection). During the first flexible NIR fluorescence endoscopy
procedure a standard clinical tattoo will be applied distally of the lesion (6
o*clock position) to enable identical visualization during the second
procedure. In addition, areas will be digitally video recorded to enable
biopsies of the same area between procedures. Biopsies will be extensively
analyzed (described below). Optionally, we will ask patients if they would like
to undergo optoacoustic endoscopy. This is a form of endoscopic ultrasound
which is able to detect bevacizumab-IRDye800CW up to 2 cm in depth. The
procedure is comparable with NIR fluorescence endoscopy. If patients agree,
after removal of the NIR fluorescence endoscope the optoacoustic endoscope will
be introduced in the rectum of the patient for detection of
bevacizumab-IRDye800CW in deeper areas of the tumor.

Patients included in this study will be administered Bevacizumab-IRDye800CW
intraveneously in tracer dose (4.5 mg in 5 ml) and observed for one hour. Two
days after tracer administration patients undergo flexible near-infrared
fluorescence endoscopy with MDSFR/SFF spectroscopy including biopsies and
optionally optoacoustic endoscopy. Tracer injection and endoscopy procedure
will be performed twice.

Burden and risks:
In this study, safety data related to (the administration of)
Bevacizumab-IRDye800CW will be collected and evaluated. Based on clinical
experience in the first five breast cancer patients (NL37479.042.11), toxicity
studies and the fact that we will administrate two times a low, non-therapeutic
(single dose 4.5 mg bevacizumab-IRDye800CW vs 5 mg/kg bevacizumab in
therapeutics), no adverse events are expected following administration of
bevacizumab-IRDye800CW. A possible side-effect following administration is a
raised blood pressure. Tracer administration will take one hour, since the
patients are observed for one hour post administration.

In the current protocol, patients will undergo fluorescence endoscopy; a
comparable procedure to standard clinical sigmoid endoscopy with bowel cleaning
by a phosphate enema. The risks of the investigational procedure are comparable
to the minimal risks of a standard clinical sigmoid endoscopy. Small
superficial biopsies will be taken. These biopsies have minimal risk of
bleeding, which mostly coagulate spontaneously. If not, which is very uncommon,
the gastroenterologist has several tools to attack this small bleeding. The
procedure will take 20 minutes and is performed by experienced
gastroenterologists. Optionally, patients will undergo optoacoustic endoscopy
following fluorescence endosocpy to detect bevacizumab-IRDye800CW in deeper
areas of the tumor. This procedure will take 10 minutes.

The time investment of the subjects is considered reasonable. The procedures at
the screening visit, the tracer administration visit and the endoscopy
procedure will take 1 to 2 hours, depending on the visit.

Benefit:
Patients are treated following standard clinical care or according to the
RAPIDO study protocol. Additional NIR fluorescence endoscopy will not have any
benefits for the participating patients.