Dalpiciclib and Pyrotinib in HER2-Positive Advanced BC: Phase 2 DAP-HER-01

The single-arm, phase 2 DAP-HER-01 study (NCT04293276) demonstrated promising efficacy and safety with the cyclin-dependent kinase 4/6 inhibitor dalpiciclib and pan HER tyrosine kinase inhibitor pyrotinib combination in HER2-positive advanced breast cancer (ABC) independent of hormone receptor (HR) status.¹

Updated results of the DAP-HER-01 study were reported at the 2023 ASCO annual meeting.² The DAP-HER-01 study enrolled patients with HER2-positive ABC who had received ≤1 prior systemic treatment in the advanced setting. Eligible patients received dalpiciclib and pyrotinib until progression, unacceptable toxicity, or no further benefit. The primary end point was objective response rate per RECIST version 1.1; secondary end points included progression-free survival (PFS), overall survival, and safety.

A total of 41 patients were enrolled and treated in the study; 40 patients were evaluable for efficacy. At a median follow-up of 19.2 months, the median PFS in the overall population was 11.0 months. Although PFS data are still not mature, the HR-negative cohort showed a trend for longer PFS compared with the HR-positive cohort (16.6 months; 95% confidence interval [CI], 7.3-not achieved vs 9.1 months; 95% CI, 5.4-11.0). The subgroup with brain metastases at baseline was associated with median PFS of 11.0 months.

The most common grade ≥3 treatment-related adverse events were leukopenia (68.3%), neutropenia (65.9%), and diarrhea (19.5%); no treatment-related deaths were reported.

Findings of the DAP-HER-01 trial suggest that the oral chemotherapy-free dalpiciclib combined with pyrotinib showed promising efficacy and manageable toxicity in the treatment of HER2-positive ABC, including in patient cohorts with HR-negative disease or brain metastases.

Sources:

1. Yan M, Niu L, Lv H, et al. Dalpiciclib, a novel CDK4/6 inhibitor, combined with pyrotinib for HER2+ advanced breast cancer: interim results of a phase II trial. Abstract presented at: ESMO Congress, September 17-21, 2021; Paris, France. Poster 276P.
2. Yan M, Niu L, Lv H, et al. Updated results from a phase 2 study on dalpiciclib and pyrotinib, a dual-oral chemotherapy-free regimen in HER2-positive advanced breast cancer (DAP-HER-01). Abstract presented at: ASCO Annual Meeting, June 2-6, 2023; Chicago, IL. Abstract 1045.