PARSIFAL: A randomized, multicenter, open-label, phase II trial to evaluate palbociclib in combination with fulvestrant or letrozole in endocrine-sensitive patients with estrogen receptor (ER)[+]/HER2[-] metastatic breast cancer.

Abstract No : 1007

Abstract Type : Oral Abstract Session

Indication : ER+ HER2-VE

Intervention : palbociclib in combination with fulvestrant or letrozole

Company : Pfizer

Technology : Small Molecule


By March 9th, 2020, 256 PFS events occurred. Pts characteristics were well balanced. Median age was 62 years (range: 25–90), 56.6% were ECOG 0, 40.7% had “de novo” metastatic disease, 48% had visceral disease, and 43.6% with $3 organ sites involved. At median follow-up of 32 mo, median PFS was 27.9 mo (95% confidence interval [CI], 24.2- 33.1) with PF and 32.8 mo (95% CI, 25.8-35.9) with PL (HR: 1.1; 95% CI, 0.9-1.5; P = 0.321). No differences were observed for pts with or without visceral involvement (HR: 1.3 and HR: 0.97 respectively, interaction P = 0.275), and for “de novo” or recurrent metastatic disease (HR: 1.1 and HR: 1.1 respectively, P = 0.979). The 4-year OS rate was 67.6% in PF and 67.5% in PL arm (HR: 1; 95% CI, 0.7-1.5; P = 0.986). No differences were observed in ORR or CBR between arms. Grade $3 adverse events were similar in both arms, being neutropenia and leukopenia the most frequent. No treatment-related deaths were reported.


This study was not able to identify any improvement in PFS for PF over PL in patients with endocrine-sensitive ER[+]/HER2[-] MBC. As both arms demonstrated comparable 4 years-OS, PF is a reasonable alternative to PL in this setting.


PARSIFAL study did not show stastically superiority in PFS for fulvestrant + palbociclib over letrozole + palbociclib iin first-line metatstatic HER2-VE breast cancer. As per Delveinsight's analysis it is upto physiscian choice to pick any of the treatment for their patients.