by Lauren C. Brown, Sherene Loi
The Breast:
Published: December 31, 2021
Abstract
There is an emerging body of evidence regarding the use of immunotherapy
in early-stage triple negative breast cancer (TNBC), with the recent
publication of several phase III and randomised phase II studies examining the
role of immune checkpoint inhibitors (ICI) in the neoadjuvant setting in
combination with chemotherapy. Evidence to date suggests that the addition of
PD-1/PD-L1 inhibitors results in slight increases in the rate of pathologic
complete response (pCR) seen at the time of surgery, and improved event free
survival (EFS) has now been reported. However, a number of questions remain
such as the optimal chemotherapy backbone; whether traditional third generation
chemotherapy regimens can safely be de-escalated in the presence of an ICI; and
the most appropriate sequencing of treatment in order to best harness a durable
immune response and if continuation of post operative ICI is needed if one
achieves a pCR. A predictive biomarker is also yet to be established, given
that PD-L1 protein expression does not seem discriminatory. Given that
long-term clinical outcome improvements seen thus far in early stage trials do
not seem to be mediated through small changes in pathological complete response
rates, new approaches in early stage trial design are now needed.
