Findings from SONIA, a phase III Dutch study comparing "the sequence of an aromatase inhibitor plus CDK4/6 inhibitor as first-line treatment followed by fulvestrant as second-line treatment (CDK4/6 inhibitor first-line group") did not improve overall survival compared with second-line treatment. Rather, this treatment regimen increased treatment-related and financial toxic effects in patients with HR-positive HER-2 negative advanced breast cancer. Following an analysis of 1050 patients enrolled in SONIA, median overall survival was 47.9 months with first-line CDK4/6 inhibitor and 48.1 months with second-line CDK4/6 inhibitor
To learn more about the SONIA study, click here.
Sources mentioned:
- Wortelboer N, van Ommen-Nijhof A, Konings IR, et al. Overall Survival With First-Line vs Second-Line CDK4/6 Inhibitor Use in Advanced Breast Cancer A Randomized Clinical Trial JAMA Oncology; Published online 19 February 2026. doi: 10.1001/jamaoncol.2025.6585
- Valenza C, Burstein HJ. Lessons From the SONIA Trial on Timing of CDK4/6 Inhibitors in Advanced Breast Cancer—The Sooner, the Better? JAMA Oncology; Published online 19 February 2026. doi: 10.1001/jamaoncol.2025.6345
The SONIA result is an important sequencing lesson: giving a CDK4/6 inhibitor first-line did not improve overall survival over saving it for second-line, yet added toxicity and cost. For patients, that means the same survival with less burden if the drug is sequenced later. In heme onc and solid tumour practice alike, these sequencing questions are becoming central, because doing more earlier is not automatically doing better.
ReplyDeleteA median overall survival of 47.9 versus 48.1 months is as close to identical as trials get — SONIA really is the definitive answer on CDK4/6 sequencing, not just a signal. The financial toxicity point deserves as much attention as the efficacy one, since sparing patients an expensive line that adds no survival benefit is genuine value-based care. The Valenza and Burstein editorial's "the sooner, the better?" title now reads as delightfully provocative.
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