Further evidence for the benefit of adding immune checkpoint inhibitors to neoadjuvant chemotherapy in patients with early high-risk estrogen receptor–positive, HER2-negative (HR+/HER2–) breast cancer comes from results of two randomized trials presented at the annual meeting of the European Society for Medical Oncology.
In the KEYNOTE-756 trial, adding pembrolizumab (Keytruda) to neoadjuvant chemotherapy resulted in an 8.5% increase in pathologic complete response (pCR) rates, compared with chemotherapy alone, regardless of the patients’ programmed death ligand-1 (PD-L1) status, reported Fatima Cardoso, MD, director of the breast unit at the Champalimaud Clinical Center in Lisbon.
In the Checkmate 7FL trial, a study bedeviled by unexpected circumstances, the addition of nivolumab (Opdivo) to neoadjuvant chemotherapy resulted in a 10.5% absolute increase in pCR rates, compared with chemotherapy alone, reported Sherene Loi, MBBS, PhD, from the Peter MacCallum Cancer Centre in Melbourne.
A new paradigm?
, professor of breast cancer medicine at the Royal Marsden Hospital and Institute of Cancer Research in London.
“Is the management of ER-positive breast cancer going to change with immunotherapy? Can we improve pCR rates? Yes, we can. We’ve seen a significant improvement in two separate studies, albeit the rates are only at 24%, and at this point, it’s unclear if this will translate into a better event-free survival [EFS] because we have to wait and follow the data,” he said.
The data from the two studies suggest that the patients who are likely to benefit most would be those with higher-grade tumors, luminal B subtype tumors, and, possibly, those whose tumors express higher levels of PD-L1, although the definition of PD-L1 positive depends on the assay used, he said
“I think we have to make better efforts to evaluate whether genomic or immune signatures can further define those who have most to gain, and I would urge investigators in both studies to do more digging into understanding this, because you might really enrich the patients who have the most to gain from the is approach,” Dr. Johnston said.
Checkmate 7FL details
In this prospective, randomized multicenter trial patients received four cycles of neoadjuvant paclitaxel followed by four cycles of doxorubicin and cyclophosphamide (AC) and surgery with adjuvant endocrine therapy. In arm A, 257 patients received neoadjuvant and adjuvant nivolumab. In arm B 253, patients received a nivolumab placebo in both the neoadjuvant and adjuvant settings.
Eligible patients had newly diagnosed ER+/HER2– breast cancer centrally confirmed. Patients with T1c or T2 tumors who were clinically node positive on histology and those with T3 or T4 tumors of any nodal status were eligible. Patients were required to have grade 3 histology as determined by the local pathologist, or grade 2 with low ER expression.
Patients were stratified by PD-L1 status, tumor grade, axillary nodal status and frequency of AC delivery (every 2 or 3 weeks) and were then randomized into one of the two treatment arms.