2017 ASCO Annual Meeting!
Session: Breast Cancer—Metastatic
Type: Oral Abstract Session
Time: Saturday June 3, 1:15 PM to 4:15 PM
Location: Hall D1
Overall survival results from the randomized phase II study of palbociclib (P) in combination with letrozole (L) vs letrozole alone for frontline treatment of ER+/HER2– advanced breast cancer (PALOMA-1; TRIO-18).
2017 ASCO Annual Meeting
J Clin Oncol 35, 2017 (suppl; abstr 1001)
Author(s): Richard S. Finn, John Crown, Istvan Lang, Katalin Boer, Igor Bondarenko, Sergey O. Kulyk, Johannes Ettl, Ravindranath Patel, Tamas Pinter, Marcus Schmidt, Yaroslav V. Shparyk, Anu Thummala, Nataliya L. Voytko, Camilla Fowst, Xin Huang, Sindy Kim, Dennis J. Slamon; David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA; Irish Cooperative Oncology Research Group, Dublin, Ireland; National Institute of Oncology, Budapest, Hungary; Szent Margit Korhaz, Onkologia, Budapest, Hungary; Dnepropetrovsk State Medical Center, Dnipropetrovsk, Ukraine; Municipal Treatment-and-Prophylactic Institution, Donetsk, Ukraine; Technical University of Munich, Munich, Germany; Comprehensive Blood and Cancer Center, Bakersfield, CA; Petz Aladar Megyei Oktato Korhaz, Gyor, Hungary; Johannes Gutenberg Universität, Mainz, Germany; Lviv State Oncological Regional Medical and Diagnostic Center, Lviv, Ukraine; Comprehensive Cancer Centers of Nevada, Las Vegas, NV; Kyiv City Clinical Oncology Center, Kyiv, Ukraine; Pfizer Italia Srl, Milan, Italy; Pfizer Inc., La Jolla, CA; Pfizer Inc., San Diego, CA
Background: Preclinical data identified a synergistic role for P and hormone blockade in blocking growth of ER+ breast cancer (BC) cell lines. PALOMA-1 was an open-label phase II trial comparing progression-free survival (PFS) in patients (pts) with advanced ER+/HER2– BC treated with P+L or L alone. Median PFS increased with addition of P to L to 20.2 mos (vs 10.2 mos with L alone; HR = 0.488), with an acceptable safety profile, leading to accelerated approval by the US FDA. These results were confirmed in the phase 3 PALOMA-2 trial. At the time of the final PFS analysis, overall survival (OS) data were immature with only 61 events in both arms and a median follow-up of < 30 mos with a trend in favor of P+L vs L (37.5 vs 33.3 mos; HR = 0.813; P= 0.211). Here we present final OS results. Methods: PALOMA-1 was a 2-part study evaluating P+L in ER+/HER2– advanced BC. Part 1 enrolled postmenopausal pts with this subtype using only ER+/HER2– while Part 2 enrolled pts of this subtype additionally screened for CCND1 amplification and/or loss of p16. The primary endpoint was investigator-assessed PFS. Secondary endpoints included objective response rate, OS, safety, and correlative biomarker studies. A total of 165 pts were randomized; 66 in Part 1 and 99 in Part 2. Baseline characteristics were balanced between treatment arms. In both parts, pts were randomized 1:1 to receive P+L or L alone. OS data were collected as well as post-study therapy. Results: As of Dec 2016, there were 116 OS events. Median OS was 37.5 mos (95% CI: 31.4, 47.8) with P+L vs 34.5 mos (95% CI: 27.4, 42.6) for L (HR = 0.897 [95% CI: 0.623, 1.294]; P= 0.281). Median OS was 37.5 vs 33.3 mos (HR = 0.837; P= 0.280) for Part 1 and 35.1 vs 35.7 mos (HR = 0.935; P= 0.388) for Part 2. 78.6% of pts in the P+L arm received post-study systemic therapy vs 86.4% in the L arm. More pts in the L arm received ≥3 lines of therapy (37% vs 18%). Further subgroup analyses and details on post-study therapies will be presented. Conclusions: In PALOMA-1, P+L provided a statistically non-significant trend towards an improvement in OS. Survival data from the phase III, PALOMA-2 study is awaited. Sponsor: Pfizer; Clinical trial information: NCT00721409