Abstract 227P
Background
Early metastatic relapse of triple-negative breast cancer (mTNBC) patients (pts), at <12 months (mos) from end of curative therapy represents a highly aggressive disease that requires clinical and molecular characterization compared to those with late relapse (≥12 mos).
Methods
We used clinical and molecular data from pts with mTNBC enrolled in the ongoing precision medicine trial STING (NCT04932525). Genomic analysis was carried out for each patient by using the FoundationOne CDx and Liquid assay. Comparisons used a Pearson's chi-squared Wilcoxon test.
Results
From December 2020 to November 2022, 67 pts with mTNBC were included: 40 early relapse (<12 mos) and 27 late relapses. 50 ctDNA and 44 tissue were performed, at least one molecular alteration was found in 90% (n=45) ctDNA and 77% (n=34) tissue profiling pts. Pts with early relapse had no difference in mutations than late relapse in ctDNA (96% [n=26] vs 83% [n=19] p= 0.26 and tissue (80% [n=24] vs 71% [n=10] p= 0.80, respectively). Also, there was no difference in copy number variations (CNV) between early and late relapsed pts in ctDNA 41% [n=11] vs 17% [n=4] (p= 0.1) and tissue 70% [n=21] vs 50% [n=7] (p= 0.34), respectively. In addition, the proportion of gene rearrangements in ctDNA 59% [n=16] vs 43% [n=10] (p= 0.4) and in tissues 30% [n=9] vs 35% [n=5] (p= 0.97) was no different between early and late relapse pts. The median TMB of pts with early or late relapse was 3 vs 4 (p = 0.4) in ctDNA and 2.52 vs 3.78 (p = 0.1) in tissue. 7.5% (n=93) pts with early relapsed had a TMB high vs 0% in late relapse patient. The most common cancer-related alterations (mutation, CNV and rearrangements) identified in early relapses were TP53 (9.5% n=50), BRCA2 (1.9%, n=10), NF1 (1.9%, n=10). The proportion of actionable cancer-related alterations in early relapses and late relapses were 16%, and 5%, respectively. The actionable cancer-related alterations identified in the early relapse were AKT1 (n=2), PIK3CA (n=8), and PTEN (n=2).
Conclusions
Pts with early relapse have very \"difficult to treat\" disease. No differences in cancer-related alterations were observed in these pts, but a substantial rate of targetable alterations, hence a great interest in molecular profiling to identify new effective therapies.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
F. André: Financial Interests, Institutional, Research Grant: AstraZeneca, Lilly, Novartis, Pfizer, Roche, Daiichi; Financial Interests, Institutional, Other, advisory board: Guardant Health; Financial Interests, Institutional, Other, Advisory board: MedImmune, Gilead, Relay therapeutics; Other, Founder: Pegacsy. A. Italiano: Financial Interests, Personal, Advisory Board: Bayer, Roche, Philips, Chugai, GSK; Financial Interests, Institutional, Invited Speaker: Bayer, AstraZeneca, Roche, MSD, Ipsen, Merck. B. Pistilli: Financial Interests, Institutional, Advisory Board: AstraZeneca, Seagen, Lilly, Daiichi Sankyo, MSD; Financial Interests, Institutional, Invited Speaker: Gilead, Novartis, AstraZeneca, Gilead, Seagen, MSD, Novartis; Financial Interests, Personal, Advisory Board: Pierre Fabre, Daiichi Sankyo; Financial Interests, Personal, Other, travel support: AstraZeneca, Pierre Fabre, MSD, Daiichi Sankyo; Financial Interests, Institutional, Research Grant: AstraZeneca; Financial Interests, Institutional, Funding: Daiichi Sankyo; Non-Financial Interests, Project Lead: Unicancer. All other authors have declared no conflicts of interest.