San Antonio Breast Cancer Symposium

San Antonio Breast Cancer Symposium

Perspective from Andrew D. Seidman, MD
December 22, 2016
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Pertuzumab improves PFS for HER-2–positive breast cancer

Perspective from Andrew D. Seidman, MD
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SAN ANTONIO — The addition of pertuzumab to trastuzumab plus an aromatase inhibitor was well tolerated and prolonged PFS in postmenopausal women with HER-2–positive locally advanced or metastatic breast cancer, according to results of the phase 2 PERTAIN trial presented at San Antonio Breast Cancer Symposium.

Grazia Arpino , MD, PhD, from Rimawi M Università degli Studi di Napoli Federico II in Naples, Italy, and colleagues evaluated data from 129 HER-2–positive patients with locally advanced or metastatic breast cancer who had not received prior systemic therapy other than endocrine therapy.

All patients received an 8-mg/kg loading dose of trastuzumab (Herceptin, Genentech) followed by 6-mg/kg every 3 weeks plus 1 mg daily of anastrozole or 2.5-mg letrozole. Researchers randomly assigned 129 patients to that combination alone and 129 patients to also receive an 840-mg loading dose of pertuzumab (Perjeta, Genentech) followed by 420 mg every 3 weeks. At the researcher’s discretion, induction chemotherapy could be given for 18 to 24 weeks prior to starting endocrine therapy.

The primary endpoint was PFS, stratified by induction chemotherapy and time since adjuvant hormone therapy.

In total, 32.6% of patients in the pertuzumab arm and 28.7% in the control arm underwent induction docetaxel. Another 24.8% of patients in the pertuzumab arm and 24% of patients in the control arm underwent induction paclitaxel.

The objective response rate was 63.3% (95% CI, 95% CI, 53.5-72.3) in patients who received pertuzumab and 55.7% (95% CI, 45.7-65.3) in patients who received trastuzumab plus an aromatase inhibitor, which did not reach statistical significance. The median duration of response was 27.1 months for patients who received pertuzumab compared with 15.1 months in patients who received the control (P = .02).

The median OS was not reached in either treatment group, according to the researchers.

The median PFS was 18.9 months for patients who received pertuzumab compared with 15.8 months in patients who received trastuzumab (HR = 0.65; 95% CI, 0.48-0.89).

All-grade adverse events were observed in 122 patients in each arm (pertuzumab, 96.1% vs. control, 98.4%). More than half of patients in the pertuzumab group experienced a grade 3 event (50.4%) compared with 38.7% in the control group.

The most common grade 3 or worse events included hypertension (pertuzumab, 10.2% vs. control, 11.3%), diarrhea (7.1% vs. 2.4%) and neutropenia (3.1% vs. 6.5%).

The researchers concluded: “PERTAIN met its primary endpoint: [pertuzumab, trastuzumab and aromatase inhibitor] is effective and well-tolerated, and may offer a novel treatment option for patients with HER-2–positive/hormone receptor–positive [locally advanced or metastatic breast cancer].” – by Melinda Stevens

Reference:

Arpino G, et al. Abstract S3-04. Presented at: San Antonio Breast Cancer Symposium; Dec. 6-10, 2016; San Antonio, Texas.

Disclosure: Arpino reports consultant roles with Amgen, Celgene, Novartis and Roche; speakers bureau roles with Amgen, Celgene, GlaxoSmithKline, Novartis and Roche; and contracts with Eisai, GlaxoSmithKline, Novartis and Roche. Please see the abstract for a list of all other researchers’ relevant financial disclosures.