Somatostatin receptor scintigraphy in patients with multiple myeloma or plasmocytoma

Multiple Myeloma

Multiple Myeloma (MM) is clonal B cell disorder characterised by a monoclonal
plasma cell population in bone marrow, with bone pain, hypercalceamia, and
kidney dysfunction as clinically presenting symptoms. In the majority of the
patients the disorder is disseminated through the bone marrow compartment but
in 5% of the patients MM presents as localized disorder i.e. a plasmacytoma.
The abnormalities of the skeleton can be identified by X-ray examination and
demonstrates frequently the characteristics osteolytic defects9. However, in
30%-40% of the patients no osteolytic defects can be demonstrated but only
osteoporosis. Post-treatment the X-ray abnormalities persist and no distinction
can be made at an early time point whether vital tumor cells are still present
or whether the skeleton abnormalities contain normal cells. Sofar only FDG-PET
has been used to study the metabolic activity of the malignant plasma
cells9-11. Several small studies have demonstrated that osteolytic lesions
might be FDG-PET positive due to their higher metabolic activity.
Different in vitro studies have demonstrated that the somatostatin receptor is
expressed on malignant plasma cells12-13. However, so far no clinical studies
have been published in MM with SRS. Especially in view of the high somatostatin
receptor expression it is conceivable that SRS might be a good alternative to
the study the presence of the malignant plasma cells. The whole body scan might
be of value to demonstrate whether a localized versus disseminated disorder is
present. Clinically this is an important question since patients with localized
disease are treated with high dose radiotherapy while patients with a
disseminated disorder are treated with intensive chemotherapy including
autologous stem cell transplantation14. An additionally value of this scanning
technique is that the degree of uptake can be quantified which might indirectly
be an indicator of the malignant character of the plasma cells as has been
demonstrated for FDG-PET in lymphoma patients. Patients with a high FDG-PET
uptake did have an aggressive lymphoma15.
Preliminary results in 4 MM or plasmacytoma patients demonstrated a high SRS
binding in some of the affected areas (histological proven) which normalized
after chemotherapy in two MM patients.
Based on these results it is of clinical relevance to study the value of SRS in
MM patients and to what extent it can be used as marker for localized or
disseminated disorder.

Objective of the study

The present pilot study will be focused to define the sensitivity of SRS in MM
patients and in patients with plasmacytoma. This in comparison to X-ray
examination. In addition it will be investigated whether SRS can be used as an
alternative approach to detect skeleton abnormalities for painful affected
areas in the case no abnormalities on X-ray examination can be observed
including in patients with relapse MM. Bone pain is the most frequent symptom
in MM. Finally the SRS uptake will be quantified to demonstrate whether the
degree of uptake correlates with known prognostic scores and might disappear in
the case of responsive disease upon intensive chemotherapy and ASCT.

Study design

In patients with newly diagnosed MM or plasmacytoma SRS will be performed in
conjunction with the additional work-up that will be performed according to the
ongoing HOVON 49 and HOVON 65 studies or according to accepted international
guidelines9. In MM patients with painful affected area*s SRS will be performed
in conjunction with X-ray examination which might be extended with CT-scan or
MRI on basis of clinical indication.

- No specific risk
- The burden to visit the hospital and to undergo the scan.