Update on ABCSG 42/PALLAS study results of second interim analysis
The primary study aim of the PALLAS trial (Palbociclib Collaborative Adjuvant Study) is to investigate whether the addition of palbociclib to adjuvant endocrine therapy significantly improves invasive disease-free survival (iDFS) compared to standard of care adjuvant endocrine therapy alone in patients with early breast cancer. The Independent Data Monitoring Committee (IDMC) for PALLAS met on May 26, 2020, to review accumulated efficacy and safety data. They assessed, following a pre-planned second interim analysis, that the study is unlikely to show a statistically significant improvement in the primary endpoint of invasive disease-free survival (iDFS) as the predefined futility boundary was crossed. Of note, no new safety signals have been observed in patients receiving palbociclib.
Based on the IDMC’s recommendation, the Steering Committee decided (by unanimous vote) that treatment arm A patients still on active therapy should therefore stop palbociclib, and move to follow-up 1 and 2 as per protocol.
Following these news, it is essential to stress that the PALLAS trial itself, including clinical and scientific analyses, has not stopped as long-term follow-up of patients including data collection on outcomes and sample collection will proceed as planned per protocol. The PALLAS study remains to stand as a model for academically led global collaborations in which ABCSG is responsible to manage more than 240 research sites in 20 countries outside of the US as the legal trial sponsor (together with AFT as the US sponsor), which has also shown the remarkable potential of enrollment in the BIG site and goup network. Importantly, the study still provides invaluable opportunities for researchers around the world to enhance our understanding of beast cancer and explore translational research questions. The availability of 10 years of follow-up data as well as almost 6,000 tumor specimen (as the tumor block collection was a mandatory feature of patient inclusion) and tens of thousands of sequential blood samples will enable to further study questions of resistance, develop biomarkers and gain a deeper understanding of disease mechanism in the HR+ breast cancer cohort.
ABCSG sincerely thanks all global collaborators, study site teams, Investigators and particularly all patients that have contributed to this great collaboration so far and continue to provide their dedication and efforts to better understand and treat early breast cancer.