Selecteren van de optimale plaats van CDK4/6-remmer bij de behandeling van uitgezaaide hormoongevoelige (HR+) borstkanker: de SONIA studie

This is a nationwide, multicentre, randomized phase 3 study in 1,050 patients that compares two strategies in the treatment of women with HR+/HER2- metastatic breast cancer who have not received any prior systemic anti-cancer therapy for metastatic disease. Strategy A prescribes a non-steroidal aromatase inhibitor plus CDK4/6 inhibitor in first line followed by fulvestrant in second line. Strategy B prescribes a non-steroidal aromatase inhibitor in first line followed by fulvestrant plus CDK4/6 inhibitor in second line. Patients will be stratified by site of disease (visceral versus non-visceral), prior endocrine treatment in (neo)adjuvant setting (yes vs. no), CDK4/6 inhibitor and hospital.



Primary endpoint is progression-free survival after two lines of treatment (PFS2) defined as time from randomization until objective disease progression, symptomatic deterioration, or unacceptable toxicity on second line treatment, death, strategy violation, or withdrawal of consent, whichever occurs first. Secondary endpoints are overall survival, quality of life, safety and tolerability of CDK4/6 inhibitor, and objective response rate.

Treatment with a non-steroidal aromatase inhibitor combined with CDK4/6 inhibition in first line followed at progression by fulvestrant in second line (strategy A) improves progression-free survival compared to treatment with a non-steroidal aromatase inhibitor in first line followed at progression by fulvestrant combined with CDK4/6 inhibition in second line (strategy B) in women with HR+/HER2- metastatic breast cancer who have not received any prior systemic anti-cancer therapy for metastatic disease.

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Palbociclib, ribociclib or abemaciclib