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2016 ; 238
(ä): 281-288
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Growth inhibition in a brain metastasis model by antibody delivery using focused
ultrasound-mediated blood-brain barrier disruption
#MMPMID27496633
Kobus T
; Zervantonakis IK
; Zhang Y
; McDannold NJ
J Control Release
2016[Sep]; 238
(ä): 281-288
PMID27496633
show ga
HER2-targeting antibodies (i.e. trastuzumab and pertuzumab) prolong survival in
HER2-positive breast cancer patients with extracranial metastases. However, the
response of brain metastases to these drugs is poor, and it is hypothesized that
the blood-brain barrier (BBB) limits drug delivery to the brain. We investigated
whether we could improve the response by temporary disruption of the BBB using
focused ultrasound in combination with microbubbles. To study this, we inoculated
30 nude rats with HER2-positive cells derived from a brain metastasis of a breast
cancer patient (MDA-MB-361). The animals were divided into three groups: a
control-group that received no treatment; an antibody-only group that received
six weekly treatments of trastuzumab and pertuzumab; and an ultrasound+antibody
group that received trastuzumab and pertuzumab in combination with six weekly
sessions of BBB disruption using focused ultrasound. In two animals, the
leakiness of the tumors before disruption was evaluated using contrast-enhanced
T1-weighted magnetic resonance imaging and found that the tumors were not leaky.
The same technique was used to evaluate the effectiveness of BBB disruption,
which was successful in all sessions. The tumor in the control animals grew
exponentially with a growth constant of 0.042±0.011mm(3)/day. None of the
antibody-only animals responded to the treatment and the growth constant was
0.033±0.009mm(3)/day during the treatment period. Four of the ten animals in the
ultrasound+antibody-group showed a response to the treatment with an average
growth constant of 0.010±0.007mm(3)/day, compared to a growth constant
0.043±0.013mm(3)/day for the six non-responders. After the treatment period, the
tumors in all groups grew at similar rates. As the tumors were not leaky before
BBB disruption and there were no responders in the antibody-only group, these
results show that at least in some cases disruption of the BBB is necessary for a
response to the antibodies in these brain metastases. Interestingly, only some of
the rats responded to the treatment. We did not observe a difference in tumor
volume at the start of the treatment, nor in HER2 expression or in
contrast-enhancement on MRI between the responders and non-responders to explain
this. Better understanding of why certain animals respond is needed and will help
in translating this technique to the clinic. In conclusion, we demonstrate that
BBB disruption using focused ultrasound in combination with antibody therapy can
inhibit growth of breast cancer brain metastasis.
|Animals
[MESH]
|Antibodies, Monoclonal, Humanized/*administration & dosage/therapeutic use
[MESH]
|Antineoplastic Agents, Immunological/*administration & dosage/therapeutic use
[MESH]