Mouabbi, Jason

Importance Neoadjuvant systemic therapy (NST) has been associated with pathologic complete response (pCR) in up to 60% of breast cancers (BCs). The findings of this trial question the necessity of surgery. Objective To report preplanned 5-year efficacy outcomes evaluating radiotherapy alone without breast surgery in patients selected with image-guided vacuum assisted biopsy (VAB). Design, Setting, and Participants This single-arm, prospective, phase 2 nonrandomized clinical trial was conducted at 7 US medical centers and included women 40 years or older with cT1-2N0-1M0 ERBB2 -positive (formerly HER2 -positive) or triple-negative invasive BC who showed residual breast lesions after NST of less than 2 cm on imaging. Enrollment was from March 6, 2017, to November 9, 2021. Data analysis was from October to December 2024. Intervention Image-guided VAB of the tumor bed (9G with a minimum of 12 cores) was performed after standard NST. Patients with clinically node-negative disease at diagnosis and no residual cancer in the breast on post-NST VAB underwent whole-breast radiotherapy with a boost without breast or axillary surgery. Patients with initial documented nodal disease and a breast pCR on VAB underwent targeted axillary dissection, while those with residual cancer when undergoing VAB had standard breast and axillary surgery. Patients were monitored with physical examinations and mammography every 6 months. Main Outcome Measures The primary outcome was ipsilateral breast tumor recurrence. Results Fifty patients (median [IQR] age, 62 [55-77] years) were enrolled and underwent post-NST VAB. Twenty-nine (58%) and 21 (42%) patients had ERBB2 -positive and triple-negative invasive BC, respectively. Breast pCR on VAB was identified in 31 patients (62%; 95% CI, 47.2%-75.34%), and axillary pCR was identified among all 8 patients with initial nodal metastases and breast pCR on VAB who underwent targeted axillary dissection. At a median follow-up of 55.4 (IQR, 44.0-63.5) months, the ipsilateral breast tumor recurrence rate was 0%, and disease-free and overall survival rates were 100% for patients without breast surgery. Conclusions and Relevance The results of this nonrandomized clinical trial that reported preplanned 5-year outcomes suggest that omission of breast surgery in select patients after NST may be feasible, with no recurrences seen. More confirmatory studies are necessary before this new approach alters surgical practice. Trial Registration ClinicalTrials.gov Identifier: NCT02945579

e12641 Background: Many promising agents or combinations regimens relevant to breast cancer lack sufficient clinical information for use in the neoadjuvant setting. To enable acceleration of drug development by reducing time and cost of clinical trial planning and conduct, the Phase I initiative PRE-ISPY Program was created. Methods: The PRE-ISPY Program is built within the I-SPY network, with the overall aim to streamline the regulatory pathway and the processes of trial design, contracting, activation, enrollment, execution, data gathering and analysis, as well as reporting of new therapeutic agents or combinations of relevance to breast cancer. Results: The PRE-ISPY trial is an open-label platform phase IB study designed to evaluate compelling single agent or combination regimens with the overall goal of moving promising drug regimens into I-SPY2 Trial and/or into other oncology-based trials in a timely manner. Graduation of a PRE-ISPY regimen to I-SPY2 is not mandatory. The primary objectives in each study Arm are to determine safety and to obtain preliminary efficacy data of the new regimen in patients with metastatic cancer, including a cohort of breast cancer patients. Each Arm may contain a Part 1 (dose finding) and a Part 2 (dose expansion). The new treatment can be tested also in patients with other solid malignancies than breast cancer, in which the treatment may be applicable, as specified in the design of the Arm. A breast cancer specific cohort is required in Part 2. Candidate treatment regimens are selected with advice from the I-SPY2 Agent Selection Working Group. The PRE-ISPY/Phase IB trial has multiple ongoing drug regimen Arms subsequently added as new protocol appendices through amendments to a Master protocol. There is no randomization; participants are enrolled, and treatment selected according to the relevance of therapy to their disease. Prospective companion biomarkers are evaluated. The current arms under study are PRE1: ALX-148 combined with trastuzumab deruxtecan; PRE2: tucatinib combined with zanidatamab; and PRE3: vidutolimod combined with cemiplimab. Selected agents or therapeutic combinations are tested through this protocol in the I-SPY Network Centers that participate in the PRE-ISPY Program. Toxicities are graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE). Clinical responses are evaluated based on RECIST v1.1 criteria. Conclusions: Once safety is established, promising regimens can be rapidly transitioned to I-SPY 2.2 or other phase 2/3 trials. The first patient was enrolled on 2/1/2023. Clinical trial information: NCT05868226 .