Long-term outcomes of neoadjuvant trastuzumab emtansine + pertuzumab (T-DM1 + P) and docetaxel + carboplatin + trastuzumab + pertuzumab (TCbHP) for HER2-positive primary breast cancer: results of the randomized phase 2 JBCRG20 study (Neo-peaks).

PURPOSE: The randomized phase 2 Neo-peaks study examined usefulness of neoadjuvant trastuzumab emtansine + pertuzumab (T-DM1 + P) following docetaxel + carboplatin + trastuzumab + pertuzumab (TCbHP) as compared with the standard TCbHP regimen. We previously reported that pCR rate after neoadjuvant therapy tended to be higher with TCbHP followed by T-DM1 + P. We conducted an exploratory analysis of prognosis 5 years after surgery. METHODS: Neoadjuvant treatment with TCbHP (6 cycles; group A), TCbHP (4 cycles) followed by T-DM1 + P (4 cycles; group B), and T-DM1 + P (4 cycles; group C, + 2 cycles in responders) were compared. Group C non-responders after 4 cycles were switched to an anthracycline-based regimen. We evaluated 5-year disease-free survival (DFS), distant DFS (DDFS), and overall survival (OS). RESULTS: Data from 203 patients (50, 52, and 101 in groups A-C, respectively) were analyzed. No significant intergroup differences were found for DFS, DDFS, or OS. The 5-year DFS rates (95% CI) were 91.8% (79.6-96.8%), 92.3% (80.8-97.0%), and 88.0% (79.9-93.0%) in groups A-C, respectively. TCbHP followed by T-DM1 + P and T-DM1 + P with response-guided addition of anthracycline therapy resulted in similar long-term prognosis to that of TCbHP. CONCLUSIONS: In patients who achieved pCR after neoadjuvant therapy with T-DM1 + P, omission of adjuvant anthracycline may be considered, whereas treatment should be adjusted for non-pCR patients with residual disease. T-DM1 + P with response-guided treatment adjustment may be useful for minimizing toxicity. TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION: UMIN-CTR, UMIN000014649, prospectively registered July 25, 2014. Some of the study results were presented as a Mini Oral session at the ESMO Breast Cancer 2023 (Berlin, Germany, 11-13 May 2023).

Accumulation of CD56+ CD16- Natural Killer Cells in Response to Preoperative Chemotherapy for Breast Cancer.

Background: The activation of the antitumor immune responses of T cells and natural killer (NK) cells is important to induce breast tumor shrinkage via preoperative chemotherapy. We evaluated how antitumor immune responses contribute to the effects of such therapy. Methods: Forty-three patients with stages I - IV breast cancer who underwent surgery between August 2018 and Jun 2023 after preoperative chemotherapy were enrolled. Peripheral natural killer (pNK) cell activity was assessed by 51Cr-release assay, and the counts and percentages of CD4+, CD8+, and NK cells and their subsets in peripheral blood were measured before and after chemotherapy by two-color flow cytometry. Associations of cell population changes with chemotherapy responses were analyzed. Results: On univariate analysis, relative to grade (G) ≤ 1 effects, G ≥ 2 therapeutic effects were associated significantly with human epidermal growth factor receptor 2 (HER-2)+ breast cancer (P = 0.024) and post-chemotherapy CD56+ CD16- NK cell accumulation (8.4% vs. 5.5%, P = 0.042), and tended to be associated with increased pre-chemotherapy CD56+ CD16- NK cell percentages (5.4% vs. 3.3%, P = 0.054) and pNK cell activity (42.0% vs. 34.5%, P = 0.057). The accumulation and increased percentage of CD56+ CD16- NK cells in patients with G ≥ 2 effects were not associated with changes in pNK cell activity or the disappearance of axillary lymph-node metastases. On multivariate analysis, G ≥ 2 therapeutic effects tended to be associated with higher pre-chemotherapy pNK levels (odds ratio = 0.96; 95% confidence interval: 0.921 - 1.002; P = 0.067). Conclusions: The accumulation of the immunoregulatory CD56+ CD16- NK cell subset in the peripheral blood before and after chemotherapy may lead to the production of cytokines that induce an antitumor immune response. Activation of the immune response mediated by CD56+ CD16- pNK cells after chemotherapy and their high counts before chemotherapy may contribute to the improvement of therapeutic effects against breast cancer.