This phase 3 DAWNA‑A trial (NCT04842617) was conducted to determine whether adjuvant dalpiciclib enhances survival when combined with endocrine therapy (ET) in hormone receptor‑positive (HR+), HER2‑negative early breast cancer.
Phase 3 DAWNA‑A randomized 5,274 HR+/ HER2– early breast cancer patients to dalpiciclib + ET (n = 2,640) or placebo + ET (n = 2,634). At 20.3 months, dalpiciclib improved 24 month iDFS (94.7% vs 90.2%; HR 0.56; P < .0001) and 36 month iDFS (89.1% vs 86.2%), but incurred higher grade ≥3 AEs (84.4% vs 17.3%), mainly neutropenia.
At a median follow‑up of 20.3 months, 24‑month invasive disease‑free survival (iDFS) rates were 94.7% in the dalpiciclib arm versus 90.2% with placebo; 36‑month iDFS rates were 89.1% versus 86.2% (hazard ratio [HR], 0.56; 95% CI, 0.43–0.71; P < .0001). Furthermore, disease‑free survival was improved (HR, 0.53; 95% CI, 0.42–0.67; P < .0001) as was distant disease‑free survival (HR, 0.60; 95% CI, 0.46– 0.78; P < .0001). However, grade ≥3 adverse events occurred in 84.4% versus 17.3%, most frequently neutropenia (97.5% vs. 22.7%).
Therefore, adjuvant dalpiciclib confers significant efficacy benefits but is associated with increased hematologic toxicity; longer follow‑up and toxicity‑management strategies are warranted to optimize its clinical utility.
