74 Real-World Study Characterizing Patient Characteristics, Treatments, and Unmet Need in IO-Ineligible Patients With Metastatic Triple-Negative Breast Cancer

Background

Metastatic triple-negative breast cancer (mTNBC) is the most aggressive breast cancer subtype, with an estimated 15% five-year survival rate. Immunotherapy (IO) has demonstrated substantial anticancer effects, particularly in tumors overexpressing PD-L1. However, up to 70% of patients with previously untreated mTNBC may not be candidates for IO. Limited real-world (rw) evidence exists characterizing treatment patterns and clinical outcomes among these patients.

Methods

This retrospective study, using electronic health record data from the ConcertAI Patient360™ Breast dataset (01/2021–01/2025), included US patients ≥ 18 years with mTNBC who initiated first-line treatment in the metastatic setting. Patients were classified as IO-eligible and IO-ineligible: IO-eligible patients were PD-L1 positive (combined positive score ≥ 10, or other positive reported result) and had a disease-free interval (DFI) more than 12 months if treated with neoadjuvant/adjuvant IO; while IO-ineligible patients were PD-L1 negative or had a DFI of 12 months or less. Kaplan-Meier analyses were used to estimate median real-world progression-free survival (PFS), real-world overall survival (OS), real-world time to discontinuation (TTD), and real-world time to next treatment (TTNT).

Results

A total of 432 patients with mTNBC treated with first-line were identified, of whom 129 (29.9%) were IO-eligible and 303 (70.1%) were IO-ineligible. Overall, among IO-eligible and IO-ineligible, respectively, median age was 61 years; 69.0% and 61.7% were White; 79.1% and 74.0% received care in community setting; 12.5% and 5.4% had brain metastasis; and 70.6% and 73.6% had ECOG performance status 0-1, respectively. Treatments used in the first-line in patients who were IO-eligible and IO-ineligible were: 85.3% and 12.5% received IO-based regimens, 10.9% and 57.4% received chemotherapy-based regimens (without IO), and 3.9% and 30.0% received other regimens (without IO or chemotherapy), respectively. Overall, 13.2% of patients who were IO-eligible and 28.1% of IO-ineligible received first-line sacituzumab govitecan, either as monotherapy or in combination with chemotherapy, IO, or other agents. Only 43.4% and 39.0% of patients who were IO-eligible and IO-ineligible received treatment beyond first-line. Patients who were IO-eligible had longer median rwPFS, rwOS, rwTTD, and rwTTNT compared with those who were IO-ineligible (Table).

Conclusions

In this real-world cohort of patients with mTNBC treated in the first-line setting, 70% were classified as IO-ineligible. While most patients who were IO-ineligible relied on conventional chemotherapy as first-line treatment, some were treated with IO or sacituzumab govitecan despite not being recommended by NCCN guidelines in the first-line setting for this population. Clinical outcomes were significantly worse for IO-ineligible patients compared with IO-eligible patients. Overall, limited treatment options and poor clinical outcomes, particularly in IO-ineligible patients, highlight significant unmet need in this population.