E46: Predictors of Pathologic Complete Response with Neoadjuvant Chemo-Immunotherapy in Early-Stage Triple-Negative Breast Cancer

ePoster Abstract Author(s)

Lauren M. Perry, MD, MAS

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center, United States

Author(s)

Lauren M. Perry, MD, MAS

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center, United States
VS

Varadan Sevilimedu, DrPH

Biostatistics Service, Department of Epidemiology and Biostatistics
Memorial Sloan Kettering Cancer Center, United States
Natalia Polidorio, MD, PhD

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center, United States
NA

Nour Abuhadra, MD

Breast Medicine Service, Division of Solid Tumor Oncology
Memorial Sloan Kettering Cancer Center, United States
Monica Morrow, MD

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center
New York, New York, United States
GP

George Plitas, MD

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center, United States
SD

Stephanie Downs-Canner, MD

Breast Service, Department of Surgery
Memorial Sloan Kettering Cancer Center, United States

Introduction: The addition of checkpoint blockade (pembrolizumab) to neoadjuvant chemotherapy (NAC) for triple-negative breast cancer (TNBC) results in higher rates of pathologic complete response (pCR) and longer event-free survival. However, it is unknown whether certain patients may benefit preferentially from the addition of pembrolizumab to NAC. Therefore, we sought to identify demographic, clinicopathologic, and treatment features associated with pCR in a real-world patient cohort treated with chemo-immunotherapy for TNBC.

Methods: This single-institution retrospective analysis included 283 consecutive patients with TNBC treated with neoadjuvant chemo-immunotherapy from 6/1/21-1/20/23. Variables of interest were obtained from the medical record. The primary outcome was overall pCR; secondary outcomes were breast pCR and axillary pCR. Univariate and multivariable logistic regression models assessed for characteristics associated with overall, breast, or axillary pCR.

Results: The median age of patients in the cohort was 51 years. 61% of patients self-identified as White, 19% as Black, and 20% as Asian or Other race. Most patients presented with cT2 (71%) cN0 (54%) disease. The overall pCR rate was 57%, breast pCR was 58%, and axillary pCR was 67% among biopsy-proven cN+ individuals. The occurrence of an immune-related adverse event, number of immune-related adverse events, interruption or cessation of immunotherapy, chemotherapy backbone regimen, and pathogenic mutations in BRCA1 or BRCA2 were not associated with pCR. On univariate analysis, factors associated with pCR were younger age (p = 0.04), smaller clinical T stage (p = 0.009), ductal histology (p < 0.001), poor differentiation (p < 0.001), and unifocal tumors (p < 0.001). Breast and axillary pCR had similar associations (though age was not statistically significant for either), and axillary pCR was also associated with normal BMI (p = 0.04) and absence of LVI on diagnostic biopsy (p = 0.04). On multivariable analyses, ductal histology, unifocal tumors, and lower T stage remained independently associated with overall and breast pCR (Table).

Conclusions: Factors associated with pCR after neoadjuvant chemo-immunotherapy are similar to those associated with pCR after standard NAC for TNBC, including younger age, ductal histology, poor differentiation, and tumor unifocality. Ongoing basic and translational research may uncover useful biomarkers to predict response to treatment to personalize treatment and minimize morbidity.

Learning Objectives:

Upon completion, participants will be able to describe the clinical, demographic, or treatment characteristics that are associated with pCR after receipt of neoadjuvant chemo-immunotherapy for TNBC.
Upon completion, participants will be able to describe the clinical, demographic, or treatment characteristics that are not associated with pCR after receipt of neoadjuvant chemo-immunotherapy for TNBC.
Upon completion, participants will be able to describe the rates of overall pCR, breast pCR, and axillary pCR in a real-world cohort receiving chemo-immunotherapy for TNBC.