TBCRC 035: randomized phase II pharmacodynamic study of standard and reduced-dose palbociclib with endocrine therapy in hormone receptor (HR)-positive previously treated metastatic breast cancer - Pub
7 hours ago
- #palbociclib
- #metastatic breast cancer
- #dose optimization
- TBCRC 035 is a randomized phase II study comparing standard (125 mg) and reduced-dose (100 mg) palbociclib with endocrine therapy in HR-positive metastatic breast cancer.
- Primary endpoint was grade ≥3 neutropenia, which was significantly lower in the 100 mg group (33%) vs. 125 mg (56%).
- Median progression-free survival (PFS) was numerically lower with 100 mg (6.28 months) vs. 125 mg (9.28 months), but not statistically significant.
- Tumor and skin biopsies showed similar reductions in phosphorylated retinoblastoma protein (pRb) and Ki-67 at both doses, indicating robust molecular response.
- Baseline PIK3CA/TP53 mutations and higher Ki-67 were associated with shorter PFS, while changes in pRb/Rb did not correlate with outcomes.