PALOMA-1 Update: Survival With Palbociclib Not Significantly Improved in ER+/HER2- Breast Cancer
Data from PALOMA-1/TRIO-18 showed that combining palbociclib and letrozole did not significantly improve survival compared with letrozole alone among patients with breast cancer.
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Editor's Note: This article was updated to reflect an error in a previous version mistaking letrozole for fulvestrant.
In February 2015, the US Food and Drug Administration (FDA) granted accelerated approval for palbociclib in combination with letrozole as first-line treatment in postmenopausal women with ER+/HER2- metastatic breast cancer. One year later regular approval was granted for the treatment of hormone receptor-positive, HER2- advanced or metastatic breast cancer in women with disease progression following endocrine therapy.1
According to a presentation at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago by Richard Finn, MD, of the David Geffen School of Medicine in Los Angeles, California, data from PALOMA-1/TRIO-18 (ClinicalTrials.gov Identifier: NCT00721409) showed that combining palbociclib and letrozole was not significantly better for survival compared with letrozole alone.2
PALOMA-1 was a 2-part study. Part 1 enrolled postmenopausal women with ER+/HER- metastatic breast cancer; part 2 screened patients for CCND1 amplification and/or loss of p16. One hundred and sixty-five patients were enrolled — 66 in part 1 and 99 in part 2.
Median OS was similar across the 2 arms of the study: 37.5 months for palbociclib plus letrozole vs 33.3 months for letrozole alone (P = .813). Median OS was not significantly different when analyzed for patients in Part 1 and Part 2 alone.
For patients enrolled in Part 1, median OS was 37.5 months for palbociclib plus letrozole vs 33.3 months for letrozole alone (P = .280); for patients enrolled in Part 2, median OS was 35.1 months for palbociclib plus letrozole vs 35.7 months for letrozole alone (P = .388).
Post-study systemic therapy was provided to 83% of patients receiving palbociclib plus letrozole and 89% of patients receiving letrozole only.
“Given the longer median PFS, a larger sample size would be needed to detect a significance in OS in front-line ER+ breast cancer,” Dr Finn concluded.
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- The US Food and Drug Administration. Palbociclib (IBRANCE). http:// https://www.fda.gov/drugs/informationondrugs/ approveddrugs/ucm549978.htm. Accessed May 26, 2017.
- Finn RS, Crown J, Lang I, et al. 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). J Clin Oncol. 2017;34(suppl; abstr 1001).