Haematologica 2003 - Supplements

presumably through the circulation, to the second bone, yet no
myeloma cells were detected in any of the murine tissues,
demonstrating the total dependence of the cells on the human
bone marrow.
In most cases, myeloma cells grew only within the bone marrow
of the human bone. However, cells from patients with
extramedullary disease grew also along the outer surface of the
human bones. This growth pattern indicates that extramedullary
disease, while still dependent on a human microenvironment, no
longer requires elements present only in the bone marrow,
highlighting a biological difference between these and classical
myeloma cells.
The absolute dependence of the myeloma cells on the human
microenvironment offered an opportunity to study whether the
changes in the microenvironment associated with their growth are
merely consequences, or if these changes are important for
disease subsistence. Anti-angiogenic or anti-osteoclastic agents
were used to block myeloma-induced angiogenesis and
osteoclastogenesis.
Thalidomide demonstrated anti-myeloma activity only in SCIDhu
mice that contained also human liver implants, demonstrating
that metabolism is important for the drug’s anti-myeloma
efficacy. While anti-myeloma activity was associated with
reduced microvessel density, cause and effect could not be
determined. 3 Treatment with endostatin elicited response in 50%
of cases, suggesting that in some cases, angiogenesis may have a
role in the disease process.
While treatment with inhibitors of osteoclast activity effectively
halted destruction of the human bones, only Zoledronic acid and
RANK-Fc reduced the number of osteoclasts, whereas
pamidronate had no effect on osteoclast number. Still, all three
agents in addition to preserving bone had profound anti-myeloma
effects, indicating that myeloma depends on osteoclast activity.
In contrast to classical myeloma, while myeloma cells from
patients with extramedullary disease were sensitive to
thalidomide, they were completely resistant to all three antiosteoclast
agents, highlighting their independence from bone
marrow-specific microenvironment. 4
The relationship between myeloma cells and osteoclasts is also
evident in vitro: purified myeloma plasma cells attracted
committed osteoclast progenitors and, upon contact, induced their
differentiation into morphologically mature and functionally
active osteoclasts in a RANKL-mediated process. Osteoclasts, in
turn, supported survival and proliferation of purified myeloma
plasma cells for extended periods, a phenomenon that required
physical contact between the myeloma cells and osteoclasts.
These interactions induced changes in gene expression in both the
myeloma cells and the osteoclasts. Osteoclasts from myeloma
patients and from healthy donors were equally supportive of
myeloma cells and displayed similar changes in gene expression.
In contrast to supporting extended survival and proliferation of
myeloma plasma cells, osteoclasts did not support survival of
plasma cells from healthy donors, even though similar changes in
gene expression were induced in plasma cells from myeloma
patients and from healthy donors.
Studies with the SCID-hu model have demonstrated that
myeloma plasma cells are or contain a population of proliferative
cells with self-renewal capacity; that osteoclast activity is
essential for survival of tumor cells from classical myeloma; that
cells from patients with extramedullary disease no longer depend
on osteoclast activity; that metabolism of thalidomide is required
for its activity in myeloma, and suggested that in some cases
myeloma could be sensitive to anti-angiogenic therapy. These
studies also indicate that the non-myelomatous human bone
microenvironment in the SCID-hu mice, which is derived from
fetal bones and hence is not inherently abnormal, can support the
myeloma disease process.
(1) Yaccoby S, Barlogie B, Epstein J. Primary myeloma
cells growing in SCID-hu mice - a model for studying the biology
and treatment of myeloma and its manifestations. Blood.
1998;92:2908-2913.
(2) Yaccoby S, Epstein J. The proliferative potential of
myeloma plasma cells manifest in the SCID-hu host. Blood.
1999;94:3576-3582.
(3) Yaccoby S, Johnson CL, Mahaffey SC et al.
Antimyeloma efficacy of thalidomide in the SCID-hu model.
Blood. 2002;100:4162-4168.
(4) Yaccoby S, Pearse RN, Johnson CL et al. Myeloma
interacts with the bone marrow microenvironment to induce
osteoclastogenesis and is dependent on osteoclast activity. Br J
Haematol. 2002;116:278-290.
Supported by grant CA-55819 from the National Cancer Institute
P8.3
IN VIVO MOUSE MODELS FOR THE DEVELOPMENT OF
NOVEL BIOLOGICALLYBASED THERAPIES FOR MM
Constantine S. Mitsiades1,2*, Nicholas S. Mitsiades1,2*,
Andrew L. Kung3, Nikhil Munshi1,2, Kenneth C.
Anderson1,2.
1. Jerome Lipper Multiple Myeloma Center, Department of Medical
Oncology, Dana-Farber Cancer Institute, Boston MA 02115. 2.
Department of Medicine, Harvard Medical School, Boston, MA
02115. 3. Department of Cell Biology and Pediatric Oncology,
Dana-Farber Cancer Institute, Boston MA 02115, USA
The rapid bench-to-bedside translation of novel anti-cancer
therapies requires pre-clinical testing in animal models that
accurately recapitulate the natural history of human cancers and
their response to therapy. Yet, the overwhelming majority of
conventional in vivo models for MM (and other tumors) do not
optimally fulfill these requirements because they involve
subcutaneous (s.c.) tumor cell xenografts, which a) do not reflect
the diffuse, systemic nature of MM lesions; and b) place MM
cells in a cutaneous microenvironment, which is radically
different from the bone marrow (BM) milieu, which constitutes
the predominant site for MM cell homing, by virtue of its role to
promote MM cell proliferation, survival and drug resistance.
Although intravenous (i.v.) injections of MM cells can lead to
diffuse lesions, their exact anatomic location(s) cannot be readily
detected with high sensitivity and specificity by conventional
imaging modalities (due to low sensitivity of radiographic
analyses or prohibitive high cost of CT or MRI imaging), while
thorough whole-body histopathologic analyses are highly timeconsuming
and can be performed only after necropsy, and not
serially during administration of an anti-tumor regimen.
To address the limitations of conventional MM models, we
developed a series of novel in vivo MM models, which allow
establishment of diffuse MM bone lesions and their reproducible
quantitative real-time detection and spatio-temporal monitoring
using the technologies of wholebody fluorescence and/or
bioluminescence imaging. In these models, human MM cells,
stably transfected/transduced with constructs for Green
Fluorescent Protein (GFP), firefly luciferase (luc) or a fusion
GFP/luciferase (GFP+/luc+) protein, are injected i.v. in
SCID/NOD mice. The subsequently established diffuse MM
lesions can be monitored in live anesthetized mice by: a)
fluorescence imaging, where GFP+ tumors detected by
illumination of mice with near infra-red light in a LT-9500
fluorescent light box; b) bioluminescence imaging, where luc+
S50