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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Thursday, September 5, 2024
In a study presented at the 2024 American Society of Clinical Oncology (ASCO) Breakthrough conference (Abstract 1), researchers discussed the use of trial outcomes to identify tumor responsiveness in patients with different subtypes of high-risk breast cancer. Alexandra Thomas, MD, FACP, of the Duke Cancer Institute, Durham, North Carolina, and colleagues investigated pathologic complete response and early event-free survival data by disease subtype using data from the I-SPY2 trial. Their findings revealed that for the entire cohort, pathologic complete response was associated with better event-free survival.
“Uncommon histologies are overrepresented among high-risk breast cancer…and denote an area with limited trial data and of significant unmet medical need,” stated Dr. Thomas and colleagues.
A total of 144 participants were included in this study analysis. To recap, the I-SPY2 trial tested novel agents given neoadjuvantly with a chemotherapy backbone in patients with high-risk breast cancer (HER2-positive; triple-negative; and high–molecular risk, estrogen receptor–positive). To identify breast cancer subtype, histologic images of research biopsies, local biopsy, and surgical pathology reports were reviewed by pathologists, and receptor subtype distribution and pathologic complete response rates were summarized. Additionally, event-free survival was estimated, and associations between the two variables were evaluated using the Cox proportional hazard model. A combination of tumor molecular signature and receptor status was also used to determine response-predictive subtypes, and reports of disease response rates were gathered for those who received guided therapy based on their optimal response-predictive subtype.
Identified breast cancer subtypes included metaplastic (60), lobular (55), mucinous (9), micropapillary (8), and neuroendocrine (4). For the full cohort, pathologic complete response was associated with better event-free-survival (hazard ratio [95% confidence interval] = 0.12 [0.02–0.88], P = .01). Additional findings revealed that high pathologic complete responses were observed in the metaplastic group and other subsets of difficult-to-treat breast cancer with improved outcomes when therapy matched response-predictive vulnerabilities.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
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