My name is Sara Tolaney.
I'm a breast medical oncologist at the Dana-Farber Cancer Institute.
Today I'm going to be reviewing immunotherapy for the treatment
of breast cancer, with insights from the advanced disease setting.
Immunotherapy has really been
a paradigm shift in the way that we approach treatment for cancer.
It allows us to utilize the patient's own immune system to target
their malignancy and allows for the potential for long duration responses.
It's been generally associated with lower rates of
toxicity than we've previously seen with chemotherapy,
and it allows us to utilize a smart strategy to
overcome the molecular complexity of cancer.
Immunotherapy has been successful in the treatment of both hematologic and solid tumors,
and very recently we've achieved the first FDA approval for
immunotherapy in metastatic triple-negative breast cancer,
with the combination of nab-paclitaxel and atezolizumab.
Development of immunotherapy in breast cancer has been
more challenging than it has been in some other solid tumors.
One reason for this may be that breast cancer is associated with
a lower tumor mutational burden than we've seen
in cancers where immunotherapy has been quite successful,
such as melanoma and lung cancer.
If you can see here on this chart that both melanoma and
lung cancer are associated with very high tumor mutational burdens.
Whereas breast cancer has been associated with
much lower rates of tumor mutational burden.
This may be why we see
less neoantigen production and less stimulation of the immune system.
Most of the work focusing on immunotherapy in
breast cancer has initially been in the triple-negative setting.
The reasons for this are that triple-negative breast cancer has been
associated with relatively higher mutational load compared to
hormone receptor positive and HER2 positive disease,
is associated with higher levels of
tumor infiltrating lymphocytes, and has higher rates of
PD-L1 positivity compared to the other two sub-types.