Health-related quality-of-life (HRQOL) results were similar for patients with HR-positive/HER2-negative advanced breast cancer (BC) treated with a CDK4/6 inhibitor in either the first- or second-line setting. Findings from the phase 3 SONIA trial suggest that deferring CDK4/6 inhibitor treatment may not compromise HRQOL.
Kari Wisinski, MD, from the University of Wisconsin, presented the health-related quality of life (HRQOL) results of the phase 3, randomized SONIA trial (NCT03425838), which was motivated by the lack of randomized data comparing CDK4/6 inhibitors in the first- and second-line settings1,2.
The SONIA trial randomly assigned 1,050 participants with HR-positive/HER2-negative advanced BC to a CDK4/6 inhibitor in the first-line (i.e. a CDK4/6 inhibitor plus an aromatase inhibitor, followed by fulvestrant) or second-line treatment (i.e. an aromatase inhibitor, followed by fulvestrant plus a CDK4/6 inhibitor). The primary endpoint was progression-free survival after two treatment lines (PFS2), which was similar between both lines (31 months in the first-line setting vs 26.8 months in the second-line setting; HR 0.87; 95% CI 0.74–1.03; P=0.10). The key secondary endpoint, HRQOL, was evaluated using the Functional Assessment of Cancer Therapy-Breast (FACT-B) assessment at 12, 24, 48, and 72 weeks on both treatment lines and at treatment discontinuation.
No difference in HRQOL was observed between first- and second-line treatment with a CDK4/6 inhibitor, and no clinically relevant differences were observed between the two arms over time in the FACT-B total score or any of its subscales. The survey was completed by 88% (n=927) of participants, which was considered incredibly high. “Palbociclib has a relatively low toxicity profile, and grade 3 and 4 symptoms are quite uncommon, especially those impacting quality of life,” Dr. Wisinski noted.
“The SONIA trial indicated that there may be a patient population who could defer treatment with a CDK4/6 inhibitor in a second-line setting without affecting PFS2 or HRQOL. However, it should be noted that the trial primarily included an endocrine-sensitive patient population, and it remains unclear whether these results apply to other CDK4/6 inhibitors. Although promising data exists for ribociclib and abemaciclib, the key question is whether deferring CDK4/6 inhibition to the second-line setting will yield the same benefits,” Dr. Wisinski concluded.
Medical writing support was provided by Kulsoom Abdul.
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