Evaluation of VEGF expression with 89Zr-bevacizumab PET scan in patients with relapsing multiple myeloma; a feasibility study.

Multiple Myeloma (MM) is a clonal B cell disorder characterised by a monoclonal
plasma cell population in bone marrow, with bone pain, anaemia, hypercalcaemia,
and kidney dysfunction as clinically presenting symptoms. Osseous involvement
is one of the most predominant features of patients with MM; 90% of the
patients develop lytic bone lesions. Lytic bone lesions are the result of
increased bone resorption and reduced bone formation. The regular method to
detect bone lesions is skeletal survey. This technique can only detect lesions
that have lost 30% or more of the trabecular bone. Another weakness is the fact
that lesions persist after treatment with chemotherapy or radiotherapy and no
clear distinction can be made whether vital tumour cells persist in these
lesions. New bone lesions are a sign of disease progression. Furthermore they
give clinical signs as bone pain and in the worse case scenario pathological
fractures. Alternative scanning methods have been developed to visualize the
malignant plasma for example by making use of enhanced metabolic activity of
the plasma cells defined by the uptake of 18F-fluorodeoxyglucose -Positron
Emission tomography (FDG-PET. The use of FDG-PET in newly diagnosed MM patients
is well studied.

The increased FDG-uptake by the tumour is related to a high metabolic activity.
This might be a consequence of tumour hypoxia causing new vessel formation.
There seems to be a relationship between MM and angiogenesis, the formation of
new blood vessels from exciting blood vessels. There is an increased
microvessel density (MVD) of the affected bone marrow in patients with active
MM. Vascular endothelial growth factor (VEGF) is an important mediator of
angiogenesis. MM cell lines were found to express VEGF mRNA and secrete the
protein in the extracellular environment thereby stimulating angiogenesis.

Inhibition of the process of angiogenesis is used in the treatment of MM, for
instance by means of thalidomide and lenalidomide. Blocking VEGF itself can be
obtained by means of bevacizumab, a recombinant, humanised monoclonal antibody
that binds to all isoforms of human VEGF with high affinity. Treatment with
bevacizumab is well established in solid tumours, like colon cancers and renal
cell carcinomas and is currently tested in acute myeloid leukaemia and MM.

VEGF imaging with radiolabeled bevacizumab has been developed. Bevacizumab
binds VEGF and can be labeled with the PET isotope Zirconium-89 (89Zr) while
preserving VEGF binding properties. In a human ovarian tumor xenograft, PET
imaging 24 hours after injection of 89Zr-bevacizumab showed high uptake in well
perfused organs and in the tumor. A feasibility study in our institution, with
89Zr-bevacizumab PET imaging in renal cell carcinoma patients, showed a
superior diagnostic yield compared to other imaging techniques.

The high VEGF production by myeloma cells makes VEGF a very interesting target
for tumor visualization. 89Zr-bevacizumab PET imaging could be more sensitive
for myeloma lesions.

So, in conclusion, VEGF is expressed by MM plasma cells, thereby providing a
rationale that the assessment of VEGF-levels in the micro-environment of MM
tumors could potentially be used as a diagnostic tool to see if there is
disease activity. Especially in the relapsed setting this is of invaluable
importance, since conventional skeletal survey has limitations in this setting.
Furthermore, 89Zr-bevacizumab PET imaging could provide information about
treatment options and treatment response.

In the present study we will perform a feasibility study to demonstrate that
89Zirconium-bevacizumab PET scanning can visualize multiple myeloma lesions.
Data from the present study may be used to design further studies with regard
to the expression of VEGF and the selection of patients for anti-angiogenic
therapy. It might predict which patient will benefit from anti-angiogenetic
treatment and for future studies to see which patient might benefit from adding
bevacizumab to the treatment regime. Furthermore, 89Zirconium-bevacizumab PET
scanning can be used for monitoring therapy effect and the degree of uptake
defined by SUV might also provide prognostic information.
In addition, in vitro staining of bone marrow material will be performed to
demonstrate whether VEGF is up regulated by the malignant plasma cells or
surrounding cells. Furthermore, the MVD will be defined. These results will be
combined with the results of the 89Zr-bevacizumab PET imaging to see if there
is a correlation between positivity of the 89Zr-bevacizumab PET imaging and up
regulation of angiogenesis parameters.

This is a pilot-study, thus no formal group size calculation can be given. For
the purpose of this study, 20 patients will be included. Patients must have a
relapsing multiple myeloma according to international guidelines. A bone marrow
biopsy and a FDG-PET scan will be performed. It is expected that 20 patients
will cover the variability of the 89Zr-bevacizumab uptake of MM patients.
Currently, the total number of patients fulfilling the eligibility criteria of
this study is 20-30 on a yearly basis.

4.1 Timetable baseline T=0 T=1

Evaluation
in-exclusion criteria X
Informed consent X
FDG-PET scan X
Bone marrow biopsy X
89Zr bevacizumab injection X
89Zr bevacizumab imaging X

T=1: 4 days aftertracer injection

Adverse event that are related to 89Zr-bevacizumab PET imaging:
- Hypersensitivity reactions to bevacizumab within a short term after
administration (within 3 hours).
- Hypertension can occur after administration of bevacizumab. However the risk
is considered minimal due to the low tracer dose used in this study (see IMPD).
So far no side effects have been seen using 89Zr-bevacizumab