Efficacy comparison of anthracycline and taxane when added to immune checkpoint inhibitor in neoadjuvant chemotherapy of triple negative breast cancer: Clinical evidence from size-reduction measurement by ultrasound.

Abstract

e12584 Background: Most chemotherapeutics can improve responses to immune checkpoint inhibitors (ICI) by increased immunogenicity. Anthracycline(AC), taxane(T) and platinum (CDDP) has most direct cytotoxic effect in neoadjuvant chemotherapy (NAC) of triple negative breast cancer (TNBC), but which one deserve the most immunostimulatory activity linked to their capacity of to kill cancer cell still unknown. Methods: A total of 91 patients with complete data of size measurement by ultrasound (US) were identified for the study from 363 consecutive TNBC patients received NAC between November 2010 to August 2022. They were divided into 3 groups. The 1st group patients received AC first, then T with CDDP, 2nd group in reverse sequence (T and CDDP first) and 3rd group, sequence as group 2 but adding ICI (pembrolizumab). Tumors size measured by US before chemotherapy, after 1st and after 2nd regimen of chemotherapy. Percentage of size reduction of tumor maximal diameter (cm), surface area (transverse x longitudinal diameter, cm2) and volume (measured by 1/6 p x transverse x longitudinal x height cm3) were calculated. Statistically significant was calculated using the Mann-Whitney U test for percentage of size reduction and Pearson's chi-squared test for pCR rate, p-value < 0.05 was considered significant. Results: There were 14, 56 and 21 patients in group 1, 2 and 3, respectively. The significant difference of pathologic complete response rates 7.1%, 44.6% and 76.2% in each group as shown. The volume, surface area and maximal tumor size reduction percentage after 1st regimen chemotherapy in group 1 (AC), group 2 (T+CDDP) and group 3 (ICI+T+CDDP) were -67.24, -55.43, -31.13; -85.45, -72.13, -45.61 and -87.13, -69.75, -45.02, respectively, and size reduction after 2nd regimen chemotherapy in group 2 (AC) were, -42.19, -30.19, -21.13; and group 3 (ICI+AC) were -77.78, -50.76, -30.65; respectively. A statistical non-significant trend of greater size reduction in ICI+ AC than AC alone was found. Conclusions: The study is the first, direct evidence demonstrated the synergistic effect of size reduction after NAC for TNBC with AC and ICI, but not T. It supports the potential benefit of combining chemotherapy with immunotherapy such as Tonic trial reported. [Table: see text]