EXPLORATORY CLINICAL TRIAL USING BR55 TARGETED ULTRASOUND CONTRAST AGENT IN THE DETECTION OF PROSTATE CANCER BY MOLECULAR IMAGING OF VEGFR2

Neo-angiogenesis is the process by which new blood capillaries are formed from
existing blood vessels. In the case of cancer lesion as early as they can reach
a size of 1.2 mm, the process of neo-angiogenesis is initiated and maintained
by growth factors, cytokines and a range of other chemical mediators. In
particular, Vascular Endothelial Growth Factor (VEGF) is an important mediator
of angiogenesis in prostate cancer and its corresponding receptor VEGFR (type 1
or 2) is overexpressed in prostate cancer compared with nonmalignant prostate
tissue. Research has also shown that VEGF overexpression is associated with
poor outcomes in prostate cancer.
Preclinical studies support a high efficacy of BR55 agent for detecting VEGFR2
receptor.
Although animal experiments showed promising results, the risk of clinical
failure remains high for ultrasound targeted agents. The leading cause of
failure tends to be lack of efficacy, due in part to the lack of predictive
animal models and absence of pre-existing results in humans.
Therefore, before embarking upon a formal development program, it is absolutely
necessary to conduct an exploratory clinical trial using BR55 and assess if
this targeted agent is able to selectively enhance the echogenic signal in
prostate cancer lesions compared to surrounding normal parenchyma and the
eventual association of such specific enhancement with the overexpression of
VEGFR2 in the tumoral tissue compared to the normal parenchyma.

Primary Objective:
To assess the ability of BR55 to identify area(s) of VEGFR2 expression in human
prostate by ultrasound molecular imaging on the basis of a visual score in
comparison with histopathology analysis (location based on expression of VEGFR2
in tissue specimens determined by immuno-histochemistry, IHC).

Secondary Objective:
To evaluate the specificity of BR55 targeting for prostate cancer relative to
normal prostate gland on the basis of a visual score in comparison with routine
histopathology analysis and IHC assessment of VEGFR2 expression in tissue
specimens.

This is an exploratory phase, single centre, open label, prospective study to
assess the ability of the lipopeptide BRU2248 as an active ingredient to bind
with VEGFR2. The new ultrasound targeted contrast agent carrying BRU2248, code
name BR55, will specifically enhance
ultrasound signals from malignant tissues in the prostate on the basis of
ultrasound detection of over-expression of VEGFR2 in those tissues in
comparison to the surrounding normal parenchyma.
The Investigator is requested to enrol 12 patients presenting with at least one
focal prostate cancer lesion as established by previous biopsies and already
scheduled for prostatectomy. This lesion will be further referred as *target
prostate lesion* throughout this protocol.
All the enrolled patients with focal prostate cancer lesion will be submitted
to the Transrectal Ultrasound diagnostic imaging procedure incluing
Contrast Enhanced Ultrasound (CEUS) with BR55 agent.
The study will be conducted in two steps:
1) The dose(s) of 0.01 mL/kg (dose A) and 0.02 mL/kg (dose B) (in case of no
enhancement detected with the dose A) of BR55 will be used for the 1st and 2nd
bolus respectively in the first 4 patients. In case of positive contrast
enhancement within the prostate, the same
dose(s) will be used for the other 8 patients.
2) In case of no observed binding within targeted prostate lesion by visual
assessment in step 1 despite positive IHC results, the injected dose(s) will be
increased to: 0.03 mL/kg (dose C) and 0.05 mL/kg (dose D) (in case of no
enhancement detected with the dose C) for the 1st and 2nd bolus respectively in
the last group of patients to overpass possible low sensitivity of ultrasound
methods.
The final diagnosis will be obtained for all patients through the histological
examination of the prostate gland following prostatectomy.

all enrolled patients will receive the BR55 contrast agent.1) The dose(s) of
0.01 mL/kg (dose A) and 0.02 mL/kg (dose B) (in case of no enhancement detected
with the dose A) of BR55 will be used for the 1st and 2nd bolus respectively in
the first 4 patients. In case of positive contrast enhancement within the
prostate, the same
dose(s) will be used for the other 8 patients.
2) In case of no observed binding within targeted prostate lesion by visual
assessment in step 1 despite positive IHC results, the injected dose(s) will be
increased to: 0.03 mL/kg (dose C) and 0.05 mL/kg (dose D) (in case of no
enhancement detected with the dose C) for the 1st and 2nd bolus respectively in
the last group of patients to overpass possible low sensitivity of ultrasound
methods.
The final diagnosis will be obtained for all patients through the histological
examination of the prostate gland following prostatectomy.

BR55 is a new targeted ultrasound contrast agent developed for ultrasound
molecular imaging of VEGFR2. This agent is made of perfluorobutane/nitrogen
microbubbles and a biospecific lipopeptide BRU2248 inserted in the membrane to
target VEGFR2.
The components of BR55 have been selected on the basis of their ability to
generate stable bubbles, on safety studies, and good imaging performance.
Extensive preclinical toxicological studies performed on the microbubble
contrast agent BR55 did not show particular safety concerns.
In the animal models which were imaged with BR55, higher specific attachment
was observed in the tumour site in comparison with non-targeted bubbles or non
tumoral lesions suggesting an accurate detection of cancer lesions at early
stage.
In conclusion, the data from the preclinical studies with BR55 support a
protocol for an exploratory Phase in patients as a proof of concept of efficacy
in humans, with doses starting at a dose level of 0.01 mL/kg.
The planned study is an exploratory trial in which the dose of active agent to
be studied is lower than 100 *g.
There is no expected risk for the patient.