Subsequent-abemaciclib Treatment After Disease Progression on Palbociclib in Patients With ER-positive HER2-negative Metastatic Breast Cancer.

BACKGROUND/AIM: This study investigated the efficacy of continuing cyclin-dependent kinase (CDK) 4 and 6 inhibitors in patients with estrogen receptor-positive (ER+) human epidermal growth factor receptor 2-negative (HER2- ) metastatic breast cancer (MBC) after disease progression on prior-palbociclib combined with endocrine therapy (ET). PATIENTS AND METHODS: This retrospective study based on 25 ER+/HER2- MBC patients reported the efficacy and predictive factors of subsequent-abemaciclib after disease progression on prior-palbociclib. RESULTS: The overall response rate and clinical benefit rate were 16.0% and 44.0%, respectively. The median progression-free survival (PFS) was 5.3 months. In multivariate analysis, the best overall response (BOR) to prior-palbociclib was the only independent predictive factor for PFS (p=0.015). The median time to chemotherapy was 33.9 months. The median PFS in patients treated with next-line chemotherapy after progression on subsequent-abemaciclib was 6.2 months. CONCLUSION: BOR to prior-palbociclib was the only independent predictive factor for PFS in ER+/HER2- MBC patients undergoing subsequent-abemaciclib after disease progression on prior-palbociclib.

Feasibility Study of Nanoparticle Albumin-Bound-Paclitaxel and S-1 Followed by Epirubicin/Cyclophosphamide as Neoadjuvant Chemotherapy in Patients With Operable Breast Cancer: A Prospective Study.

BACKGROUND: The efficacy and safety of nanoparticle albumin-bound (nab)-paclitaxel combined with S-1 in patients with operable breast cancer is uncertain. We evaluated the feasibility of this combination followed by epirubicin/cyclophosphamide (EC) as neoadjuvant chemotherapy in such patients. PATIENTS AND METHODS: This was an open-label, single-arm, phase II, single-institution prospective study of 4 cycles of nab-paclitaxel (260 mg/m2) administered intravenously on day 1 in combination with S-1 (65 mg/m2 orally twice daily) on days 1 to 14 every 21 days followed by EC as neoadjuvant chemotherapy. RESULTS: Of 30 patients, 1 required a dose interruption for nab-paclitaxel combined with S-1; 4 required a dose reduction for nab-paclitaxel, 1 for S-1, and 4 for EC. Mean relative dose intensities of nab-paclitaxel, S-1, and EC were 98.0%, 99.3%, and 98.2%, respectively. Overall clinical response rate was 96.7%. In histological response, grade 3, pathological complete response (pCR; ypT0/is and ypN0) rate was 63.3% and grade 2b (near pCR) was 3.3%. pCR was observed in 57.1% of luminal B human epidermal growth factor receptor type 2 (HER2)-negative patients, 55.6% of luminal B HER2-positive patients, 100% of HER2-positive patients, and 57.1% of triple-negative breast cancer patients. Grade 3/4 neutropenia was observed in 1 patient during nab-paclitaxel combined with S-1 and in 7 during EC treatments. The most frequent nonhematological severe adverse events were grade 3 peripheral neuropathy in 2 patients and grade 3 arthralgia in 2 patients during nab-paclitaxel combined with S-1. CONCLUSION: Tri-weekly nab-paclitaxel with S-1 followed by EC is effective and well tolerated as neoadjuvant chemotherapy in patients with operable breast cancer.