Abstract ES10-3: IO beyond TNBC
Authors: Curigliano G 
Published: March 2022

Abstract
Hormone receptor-positive breast cancer is not considered an immunogenic tumor, since characterized by lower level of programmed death-ligand 1 (PD-L1) expression and tumor infiltrating lymphocytes. Despite being a cold tumor some studies are addressing the question on potential role of immune-checkpoint inhibitors in the adjuvant or metastatic setting. The phase II Checkmate7A8 trial (NCT04075604) is investigating the combination of nivolumab, anastrozole, and palbociclib versus anastrozole with palbociclib as neoadjuvant therapy for postmenopausal women with luminal BC. The phase II ImmunoADAPT trial (NCT03573648) is studying the combination of tamoxifen, palbociclib, and avelumab versus tamoxifen with avelumab for patients with early-stage luminal BC, expecting to show an improvement in the radiological complete response rates assessed after four cycles of treatment. A phase I safety study is also investigating the combination of durvalumab, abemaciclib, and anastrozole in a similar population (NCT04088032). The Phase 3 CA209-7FL trial is a randomized, multicenter, placebo-controlled phase 3 study of nivolumab versus placebo in combination with neoadjuvant chemotherapy and adjuvant endocrine therapy in patients with high-risk, estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) primary breast cancer. In the HER2 positive metastatic breast cancer the combination of pembrolizumab and trastuzumab administered upon progression on a trastuzumab-based regimen was investigated in the PANACEA study, which reported a response rate of 15%, restricted to PD-L1 positive tumors with a PFS benefit in the PD-L1 population. In the KATE2 trial, the addition of atezolizumab to trastuzumab emtansine in patients previously treated with trastuzumab demonstrated no significant benefit in PFS, although numerically higher PFS and response rates were observed in the PD-L1-positive population. A subsequent underpowered analysis (due to the small number of events) of the same trial suggested a possible OS benefit for patients with PD-L1-positive tumors. The combination of trastuzumab, pertuzumab, taxane, and atezolizumab is under investigation in the first-line setting (NCT03199885). The phase III IMpassion050 (NCT03726879) trial compares atezolizumab or placebo combined with neoadjuvant chemotherapy and dual anti-HER2 blockade for early-stage HER2-positive BC. This trial includes patients with PD-L1-positive and PD-L1-negative tumors and is considering pCR rates in the PD-L1-positive and ITT population as primary endpoints. In patients who do not achieve a pCR, TDM-1 is added in the adjuvant phase. The addition of atezolizumab to an anthracycline-free regimen of neoadjuvant chemotherapy and dual anti-HER2 blockade is the objective of the phase III APTneo trial (NCT035955592). In my presentation I will cover biological rational for IO studies beyond triple negative breast cancer in the attempt to provide an ideal immunogram for this population of patients.
Citation Format: G Curigliano. IO beyond TNBC [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr ES10-3.