Dalpiciclib can prolong progression-free survival (PFS) when added to letrozole or anastrozole in patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer, according to results from the phase 3 DAWNA-2 trial. 

“These findings support dalpiciclib plus letrozole or anastrozole as a new first-line treatment option in patients with untreated HR+/HER2- advanced breast cancer,” said study investigator Binghe Xu, MD, PhD, of the Chinese Academy of Medical Sciences and Peking Union Medical College in China. Dr Xu presented these results at ESMO Congress 2022.

The DAWNA-2 trial (ClinicalTrials.gov Identifier: NCT03966898) included 456 patients with previously untreated, HR+/HER2-, locally advanced or metastatic breast cancer. The patients were randomly assigned 2:1 to receive dalpiciclib (n=303) or placebo (n=153), each in combination with letrozole or anastrozole. 

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At baseline, the median age was 54 (range, 47-63) years in the dalpiciclib arm and 57 (range, 46-63) years in the placebo arm. A majority of patients (60.4% in the dalpiciclib arm and 64.7% in the placebo arm) were postmenopausal, and a minority had progesterone receptor-negative disease (14.9% and 12.4%, respectively). 

The primary endpoint, investigator-assessed PFS, was met. The median PFS was 30.6 months in the dalpiciclib arm and 18.2 months in the placebo arm (hazard ratio [HR], 0.51; 95% CI, 0.38-0.69; P <.0001). PFS favored dalpiciclib in all major subgroups and was improved regardless of menopausal status, Dr Xu noted.

The objective response rate was higher in the dalpiciclib arm than in the placebo arm —57.4% and 47.7%, respectively (P =.0233). There were 2 complete responses in the dalpiciclib arm and none in the placebo arm. 

The median duration of response was not reached in the dalpiciclib arm and was 15.0 months in the placebo arm. 

Grade 3-4 adverse events (AEs) occurred more frequently with dalpiciclib than with placebo — 90.4% and 12.4%, respectively. The most common grade 3-4 AEs with dalpiciclib were neutropenia, leukopenia, and anemia.

Serious AEs occurred in 11.9% of patients in the dalpiciclib arm and 6.5% of those in the placebo arm. A small percentage of patients discontinued treatment due to AEs — 4% and 2%, respectively. There were 3 fatal AEs in the dalpiciclib arm and 2 in the placebo arm.

Disclosures: This study was supported by Jiangsu Hengrui Pharmaceuticals Co. Ltd. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Xu B, Zhang QY, Zhang P, et al. Dalpiciclib plus letrozole or anastrozole as first-line treatment for HR+/HER2- advanced breast cancer (DAWNA-2): A phase III trial. Presented at ESMO 2022; September 9-13, 2022. Abstract LBA16.