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Featured Poster Abstract 84:
CD8 T cell-mediated immune responses are
critical to the increased efficacy of Doxil in
BRCA1 deficient tumors
Gina Mantia-Smaldone, Victoria Gamerman, Phyllis Gimotty,
Regina Loomis, Lukas Ronner, Christopher Morse, Sandra Orsulic,
Stephen Rubin, George Coukos, Sarah Adams
BRCA-deficient tumors are vulnerable to the
immunomodulatory effects of Doxil
•
•
•
•
We hypothesized that the immunogenicity of
BRCA-/- tumors contributes to the improved
clinical response to Doxil among women with
hereditary ovarian cancer
The role of T cells in tumor clearance following
exposure to Doxil was tested using a murine BRCA1-/ovarian cancer model
Response rate to Doxil for
the treatment of recurrent
ovarian cancer
100
Higher numbers of CD3+ Tumor Infiltrating
P=0.002
Lymphocytes are present in murine BRCA1 80tumors following Doxil therapy
56%
100
80
60
Percent
•
56% of women with recurrent BRCA-associated ovarian
cancer demonstrated a response to Doxil1
In addition to causing DNA damage, Doxil increases the
vulnerability of ovarian cancer cells to T cell attack
Immunophenotypic changes in response to Doxil are
more pronounced in BRCA-/- cells
BRCA-/- tumors recruit higher numbers of T cells after
Doxil exposure
Percent
•
60
Control
40
Doxil
19%
40
20
0
20
Tumor
Innoculation
0
Expression of Fas is associated with increased Fas-FasL mediated T cell
low CD3 Sporadic
high CD3BRCA -/cytotoxicity;
which is higher
cells, is required for a
Antibody MHC I expression,
Antibody
q3-4din BRCA-/CD8 T cell Evaluated
response in a cohort of 23 women with BRCA mutations and
Doxil
Doxil
Doxil
Endpoint:
41 women with sporadic cancer treated at three institutions
Weight ≥30
between 2000-2010 for recurrent cancer. The response
to grams
-7 -6
Doxil was associated with a significant improval in overall
-5survival0
3
10
17
Experimental Day
1Adams
SF et al, Gynecol Oncol 2011
Doxil increased intratumoral T cell recruitment and overall survival
in mice with BRCA1- tumors
Both CD4 and CD8 T cell
populations were present in
BRCA1- tumors and ascites
Doxil exposure increased
cytotoxic CD8 T cells and
reduced suppressive FoxP3 T cells
Tumor
100
% of CD3 + TILs
Doxil therapy significantly
prolonged the survival of
animals with BRCA1- tumors
80
P=0.0407
60
40
20
0
CD8
CD4
Control
% of CD3 T cells
Doxil
Control
Ascites
100
Flow cytometry was performed on tumor,
ascites, spleen and peripheral blood
mononuclear cells (PBMCs). Illustrated are
the portion of CD45+/CD3+ T cells present in
representative tumor or ascites samples for
placebo or Doxil treated mice.
Doxil
FoxP3
Survival (Days)
80
60
Survival measured from the time of
tumor inoculation until animals reached
30g due to ascites accumulation
40
20
0
CD8
CD4
FoxP3
The survival advantage associated with Doxil treatment persisted in
the absence of CD4 T cells
An immunodepleting antibody
successfully eliminated CD4 T
cells from BRCA1- tumors and
ascites
In the absence of CD4 T cells, the
proportion of CD8 T cells was
higher in Doxil-treated animals
Tumor
100
% of CD3+ TILs
Doxil significantly prolonged the
survival of CD4-depleted animals
with BRCA1- tumors
80
P=0.0079
60
40
20
0
CD8
CD4
Control
FoxP3
Doxil
Control
Ascites
After treatment with anti-CD4 antibody,
a population of CD4-/CD8- cells
persisted
% of CD3 T cells
100
80
Doxil
* p< 0.05
*
Survival (Days)
60
40
20
0
CD8
CD4
FoxP3
Survival measured from the time of
tumor inoculation until animals reached
30g due to ascites accumulation
There was no statistically significant difference in survival after Doxil
treatment in the absence of CD8 T cells
An immunodepleting antibody
successfully eliminated all CD8 T
cells from BRCA1- tumors and
ascites
In mice lacking CD8 T cells, the
proportion of mature CD4 T cells,
but not suppressive FoxP3 T cells,
was higher after Doxil treatment
Tumor
*
* p< 0.05
P=0.0952
% of CD3+ TILs
100
80
60
40
20
0
The survival among animals
depleted of CD8 cells was not
improved with Doxil treatment
Doxil
CD8
Control
CD4
Doxil
FoxP3
Control
Ascites
After treatment with anti-CD8 antibody,
a population of CD4-/CD8- cells
persisted
% of CD3 T cells
100
80
Survival (Days)
60
40
20
0
CD8
CD4
FoxP3
Survival measured from the time of
tumor inoculation until animals reached
30g due to ascites accumulation
Conclusions
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•
Doxil improved survival in a BRCA1- model of ovarian cancer
This effect persisted in the absence of CD4 T cells but is diminished in the absence
of CD8 T cells
Cytotoxic CD8 T cells are necessary for the enhanced response to Doxil observed in
BRCA1- tumor bearing mice
BRCA1- deficient ovarian cancers may be more susceptible to immunotherapeutic
strategies
Limitations:
• These results represent a small pilot study
and need to be confirmed in larger
cohorts
• Unfortunately the national Doxil shortage
has limited our ability to conduct planned
experiments
This work was supported by a grant from the