Somatic Mutation Profiling and Associations with Prognosis and Trastuzumab Benefit in Early Breast Cancer
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Background: Certain somatic alterations in breast cancer can define prognosis and response to therapy. This study investigated the frequencies, prognostic effects, and predictive effects of known cancer somatic mutations using a randomized, adjuvant, phase III clinical trial dataset.
Methods: The FinHER trial was a phase III, randomized adjuvant breast cancer trial involving 1010 women. Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer were further randomized to 9 weeks of trastuzumab or no trastuzumab. Seven hundred five of 1010 tumors had sufficient DNA for genotyping of 70 somatic hotspot mutations in 20 genes using mass spectrometry. Distant disease-free survival (DDFS), overall survival (OS), and interactions with trastuzumab were explored with Kaplan-Meier and Cox regression analyses. All statistical tests were two-sided.
Results: Median follow-up was 62 months. Of 705 tumors, 687 were successfully genotyped. PIK3CA mutations (exons 1, 2, 4, 9, 13, 18, and 20) were present in 25.3% (174 of 687) and TP53 mutations in 10.2% (70 of 687). Few other mutations were found: three ERBB2 and single cases of KRAS, ALK, STK11/LKB1, and AKT2. PIK3CA mutations were associated with estrogen receptor positivity (P < .001) and the luminal-A phenotype (P = .04) but were not statistically significantly associated with prognosis (DDFS: hazard ratio [HR] = 0.88, 95% confidence [CI] = 0.58 to 1.34, P = .56; OS: HR = 0.603, 95% CI = .32 to 1.13, P = .11), although a statistically significant nonproportional prognostic effect was observed for DDFS (P = .002). PIK3CA mutations were not statistically significantly associated with trastuzumab benefit (P(interaction): DDFS P = .14; OS P = .24).
Conclusions: In this dataset, targeted genotyping revealed only two alterations at a frequency greater than 10%, with other mutations observed infrequently. PIK3CA mutations were associated with a better outcome, however this effect disappeared after 3 years. There were no statistically significant associations with trastuzumab benefit.
Afolabi H, Salleh S, Zakaria Z, Seng C, Nafi S, Aziz A Discov Oncol. 2025; 16(1):268.
PMID: 40048017 PMC: 11885200. DOI: 10.1007/s12672-025-01960-2.
HER2-Positive Breast Cancer Treatment and Resistance.
Veeraraghavan J, De Angelis C, Gutierrez C, Liao F, Sabotta C, Rimawi M Adv Exp Med Biol. 2025; 1464():495-525.
PMID: 39821040 DOI: 10.1007/978-3-031-70875-6_24.
Breast cancer genomic analyses reveal genes, mutations, and signaling networks.
Manjunath G, Sharma S, Nashier D, Vasanthaiah S, Jha S, Bage S Funct Integr Genomics. 2024; 24(6):206.
PMID: 39496981 DOI: 10.1007/s10142-024-01484-y.
Ren X, Cui H, Dai L, Chang L, Liu D, Yan W J Cancer Res Clin Oncol. 2024; 150(3):119.
PMID: 38466449 PMC: 10927816. DOI: 10.1007/s00432-024-05626-4.
Zagami P, Fernandez-Martinez A, Rashid N, Hoadley K, Spears P, Curigliano G JAMA Netw Open. 2023; 6(12):e2348814.
PMID: 38117494 PMC: 10733807. DOI: 10.1001/jamanetworkopen.2023.48814.