OBR Daily Commentary


Update on PALLAS, an International Academic Breast Cancer Study Evaluating Adjuvant Palbociclib Second Interim Analysis of Adjuvant

(PrECOG) May 29, 2020 - Study for HR+, HER2- Early Breast Cancer demonstrates that there is little chance of palbociclib reducing the risk of recurrence. The Austrian Breast & Colorectal Cancer Study Group (ABCSG), Alliance Foundation Trials (AFT), the Breast International Group (BIG), PrECOG, LLC, the German Breast Group, and the NSABP Foundation today announced that the independent Data Monitoring Committee (IDMC) for the global Phase 3 early breast cancer PALbociclib CoLlaborative Adjuvant Study (PALLAS) trial determined that the study is unlikely to show a statistically significant improvement in the primary endpoint of invasive disease-free survival (iDFS) following a preplanned interim analysis.

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Debu Tripathy, MD (Posted: June 01, 2020)


The interim analysis of the very large PALLAS trial testing the addition of 2 years of palbociclib to standard adjuvant endocrine therapy is truly a disappointment not only as negative trial, but as a rejection of the conceptual framework – that a drug known to double progression-free survival in the metastatic setting has no impact in the adjuvant setting. These results will force us to re-evaluate the fundamental biology of micrometastatic disease, in some cases dormant cells that lie in hiding without even dividing for years, that for unknown reasons can reawaken and cause clinical recurrence. Anti-proliferative drugs may not be the answer, and a better understanding of dormancy will be critical. Finally, it remains possible that longer duration of therapy, or one of the other two cyclin-dependent kinase 4/6 inhibitors (both of which are being tested) could yield a positive result.



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