Abstract PO5-19-07: A Single Arm Phase 2 Study of Peri-Operative Immune Checkpoint Inhibition and Cryoablation in Women With Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable Breast Cancer

Abstract Background: Triple negative breast cancer (TNBC) is a biologically distinct subtype with a high risk of early relapse. Patients not achieving a pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) have a 3-year event free survival (EFS) of < 60%. Approximately 1/3 of patients receiving NAC with pembrolizumab-mediated immune therapy will not achieve a pCR and of those, approximately 1/3 will experience a recurrence within 3 years. Physical disruption of tumors with local strategies such as cryoablation (cryo) induces inflammation and releases antigens that can activate tumor-specific immune responses. The combination of cryo with immune checkpoint inhibition (ICI) has been shown to induce tumor regression and prevented tumor re-challenge in pre-clinical models. Clinical studies have also demonstrated that the combination of pre-operative cryo with ICI is safe in women with operable, early-stage breast cancer and generates intra-tumoral and systemic immune responses (NCT01502592, NCT02833233). This multi-center, single arm, phase 2 study is currently evaluating the impact of cryo with standard-of-care pembrolizumab (pembro) in women with residual TNBC after taxane-based NAC, a group at high risk of early relapse (NCT03546686). Methods: Eligible women are ≥18y, with ER < 10%, PR < 10%, HER2 negative (per ASCO/CAP definition), ≥ 1.0 cm, residual operable disease after taxane-based NAC. Pts undergo percutaneous, image-guided cryo with concurrent research core biopsy 7-10 days prior to surgery and receive peri-operative pembro per standard-of-care. Adjuvant capecitabine or olaparib is recommended for all patients per local standard-of-care. Patients are stratified by NAC platinum administration, NAC anthracycline administration, and clinical nodal status (positive versus negative). The primary endpoint is 3-year Event Free Survival (EFS). Secondary endpoints include Invasive Disease-Free Survival (IDFS), Distant Disease-Free Survival (DDFS), overall survival (OS) and safety. Exploratory correlative studies will be performed on tumor and serum to characterize the immunologic impact of the intervention and to explore predictors of efficacy and toxicity. Funding sources: Conquer Cancer Foundation, Breast Cancer Research Foundation, Boston Scientific Citation Format: Heather McArthur, Elizabeth Comen, Yolanda Bryce, Stephen Solomon, Sangeetha Reddy, Isaac Chan, Baṣak Dogan, Dawn Klemow, Nisha Unni, Jorge Henrique Santos Leal, Cristal Martinez, Reva Basho, Dorothy Park, Philomena McAndrew, Brigid Larkin, David Page, William Mills, Staci Mellinger, Nicole Fredrich, Nicole Moxon, Lynette Currie, Meredith Carter, Melissa Ramos, Stephanie Rice, Sujata Patil, Margaret Gatti-Mays, Larry Norton. A Single Arm Phase 2 Study of Peri-Operative Immune Checkpoint Inhibition and Cryoablation in Women With Hormone Receptor-Negative, HER2-Negative Early Stage/Resectable Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-19-07.