Sequential paclitaxel-palbociclib showed no difference in ORR versus reverse sequence in ER+/HER2- breast cancer.

This randomized phase II trial enrolled 179 patients with estrogen receptor positive and human epidermal growth factor receptor negative breast cancer tumors greater than 20 mm and/or with lymph node metastasis. Participants were randomized to receive either weekly paclitaxel for 12 weeks followed by palbociclib and endocrine therapy for 12 weeks, or the reverse sequence of palbociclib and endocrine therapy followed by weekly paclitaxel.

The primary outcome was objective radiologic response at 12 weeks. The response rate was 59% in the paclitaxel-first arm compared to 45% in the reverse-sequence arm. This difference was not statistically significant, with a p-value of 0.058. Secondary outcomes included pathologic complete response, event-free survival, and safety, though specific data for these were not reported in the provided text.

Correlative studies utilized a predictive signature called CDKPredX. This signature identified patients who were resistant to chemotherapy but responded to palbociclib plus endocrine therapy, with a p-value of 0.03. The signature was independently validated in the CORALLEEN trial with a p-value of 0.048. Safety, tolerability, discontinuations, and adverse events were not reported in the available data.

Limitations of the study include the lack of reported safety data and the absence of specific absolute numbers for outcomes. The practice relevance is noted as not reported in the source material. Given the p-value of 0.058 for the primary outcome, the evidence regarding sequence efficacy remains uncertain and requires further confirmation in larger trials.