Long-Term Data Show Favorable Results for Frontline Pertuzumab/Trastuzumab/Docetaxel in Breast Cancer

In an end-of-study analysis of the phase 3 CLEOPATRA trial, overall survival (OS) was maintained with treatment with first-line pertuzumab (P), trastuzumab (H), and docetaxel (D) for patients with human epidermal growth factor receptor 2- (HER2) positive metastatic breast cancer (MBC).

The results were presented at the 2019 American Society of Clinical Oncology Annual Meeting being held in Chicago, Illinois, from May 31 to June 4.

The 4-year long-term follow up data builds on previous results from the trial that showed a significant improvement in progression-free survival (PFS) and OS in 808 patients with HER2-positive MBC compared with a combination of a placebo + H + D. Participants who have HER2-positive MBC and have not received chemotherapy or biological therapy for their disease were eligible for the study.

In 1 arm, participants received P on day 1 of cycle 1 followed by H and then D on day 2 of cycle 1. Participants continued to receive P followed by H and D every 3 weeks (Q3W) for subsequent cycles. In the second arm, participants received P matching placebo followed by H and then D.

P was administered as an intravenous (IV) loading dose of 840 mg Q3W on day 1 of cycle 1 and 420 mg Q3W on day 1 of subsequent cycles. T was administered as an IV loading dose of 8 mg/kg Q3W on day 2 of cycle 1 and 6 mg/kg Q3W on day 1 of subsequent cycles. D was administered as an IV dose of 75 mg/m² Q3W on day 2 of cycle 1 and 75 mg/m² (up to 100 mg/m² as per treating physician discretion) Q3W on day 1 of subsequent cycles.

In the study, the data showed an unprecedented 15.7-month increase in OS (median 56.5 months with P + H + D versus 40.8 months with placebo + H + D; HR 0.68; 95% Cl 0.56, 0.84; p <.001) with a median follow-up of 50 months.

According to the end-of-study analysis abstract, the OS HR was 0.69 (95% Cl 0.58, 0.82) favoring P + H + D. The 8-year landmark OS rates were 37% and 23%, respectively. In predefined subgroups, including patients previously treated with H in the neoadjuvant setting, OS benefit remained consistent with the overall result and previous reports, according to the data.

Overall, the safety profile of P + H + D remained consistent with the known safety profile of P. One new serious adverse effect suggestive of congestive heart failure and 1 new symptomatic left ventricular systolic dysfunction was observed since the previous analysis.

Reference

Swain S, Miles D, Kim SB, et al. End-of-study analysis from the phase III, randomized, double-blind, placebo (Pla)-controlled CLEOPATRA study of first-line (1L) pertuzumab (P), trastuzumab (H), and docetaxel (D) in patients (pts) with HER2-positive metastatic breast cancer (MBC). J Clin Oncology 37, 2019 (suppl; abstr 1020).