We spoke with Dr. Rebecca Dent, MD, at the European Society for Medical Oncology Congress 2019, held in Barcelona, Spain from September 27, 2019 to October 1, 2019. Dr. Dent shared the use of immunotherapy in early-stage breast cancer in relation to the KEYNOTE-522 study.
"The bigger question is ‘what should be the chemotherapy backbone?’ We know that certain chemotherapies can actually act like immunomodulators. If you look at specifically platinum-based chemotherapy, what we know is that actually can suppress some of the immunosuppressive elements of breast cancer, specifically looking at suppression of myeloid stem cells and tumor-associated macrophages. We have the biology to explain why it would work earlier and now we actually have a study that actually looked at that.
The KEYNOTE-522 study was looking at early, triple-negative breast cancer in the neoadjuvant setting…a really representative population with almost half the patients being node-positive. It included PD-L1 positive and PD-L1 negative, but about 80% of those patients were PD-L1 positive. The backbone of this particular study was looking at an anthracycline/taxane-platinum which is the most robust control arm you can have with the highest pathological complete response rates reported in literature and this is plus or minus pembrolizumab in the early breast cancer setting. Then the patients proceeded with surgery and then they continued on pembrolizumab (Keytruda) or a placebo.
This is the first read of the results that were presented at this meeting which showed an impressive improvement in pathological complete response rate, regardless of the definition used. The most stringent definition showed an almost 14% improvement. What was actually most interesting though was you saw an even larger benefit in the PDL-1 negative population. In those patients, again, you see greater than 15, almost 20% improvement in pathological complete response in the PD-L1 negative which we’re actually seeing hints of in some of the smaller phase II studies. Independent of PD-L1 status, immune checkpoint inhibitors seem to work."