Ann Oncol: Issue 3 | Pabosini s endocrine therapy vs chemotherapy for metastatic breast cancer that is resistant to ER-HER2-aromatase inhibitors

Palbociclib is the world's first approved CDK4/6 kinase inhibitor, an experimental, oral, targeted CDK4/6 inhibitor that selectively inhibits cell cycle protein-dependent kinases 4 and 6 (CDK4/6), restores cell cycle control, and blocks tumor cell proliferation.
Pabosini combined endocrine therapy (ET) is the standard treatment for hormone-positive and human skin growth factor-positive 2 (HE2) negative metastatic breast cancer (MBC).
, however, its efficacy has not been compared with chemotherapy in Phase III trials.
PEARE was a multi-center Phase III randomized study that recruited MPC patients with aromatic enzyme inhibitor (AIs) resistance to randomly divided into two queues.
in Queue 1 (C1), the patients were randomly divided into two groups (1:1) and treated with Pabosini combined isimetan or carpedabin.
the trial was adjusted to include queue 2 (C2) after new evidence of a mutation in the estrogen-1 (ESR1) mutation that led to AIs resistance was found, and the patient received 1:1 treatment from Pabosini Combined Fluvis group or carpatebine.
end of the disease is progress-free survival (PFS) in C2 queues and all wild ESR1 patients.
March 2014- July 2018, C1 and C2 queues included 296 and 305 patients, respectively.
in C2 queues and all wild ESR1 patients, Pabosini combined ET was better than Capertabin (medium PFS: 7.5 vs. 10.0 months; adjusted risk ratio: 1.13; 8.0 vs 10.6 months; aHR:1.11).
The three most common level 3-4 toxic side effects in the three groups of pabosinib- and isimetan, Pabosini-fluvis and capedabin were neugenic granulocyte reduction (57.4%, 55.7% and 5.5%), hand-foot syndrome (0%, 0% and 23.5%) and diarrhea (1.3%, 1.3% and 7.6%).
pabosini combined ET provides a higher quality of life (aHR:0.67 for global health deterioration).
in patients with AIs-resistant MPC, Pabosini combined ET did not have a statistical advantage over Carpett, but showed better safety and a higher quality of life.