Phase II trial of pertuzumab and trastuzumab in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer that progressed during prior trastuzumab therapy.
PURPOSE; Pertuzumab, a human epidermal growth factor receptor 2 (HER2) -targeted monoclonal antibody, potently inhibits HER2 dimerization and HER-mediated signaling pathways. Pertuzumab and the approved HER2-targeted monoclonal antibody trastuzumab have complementary mechanisms of action and result in enhanced antitumor activity when combined. This phase II trial assessed the efficacy and safety profile of the combination in patients with HER2-positive breast cancer whose disease had progressed during prior trastuzumab-based therapy.


METHODS
This was a multicenter, open-label, single-arm, Simon two-stage study. Patients with advanced HER2-positive breast cancer in whom disease progression had occurred during prior trastuzumab-based therapy received trastuzumab weekly (4 mg/kg loading dose, then 2 mg/kg every week) or every 3 weeks (8 mg/kg loading dose, then 6 mg/kg every 3 weeks) and pertuzumab every 3 weeks (840 mg loading dose, then 420 mg every 3 weeks). Treatment continued until disease progression or excessive toxicity.


RESULTS
All 66 patients were assessable for efficacy and safety. The objective response rate was 24.2%, and the clinical benefit rate was 50%. Five patients (7.6%) experienced a complete response, 11 patients (16.7%) experienced a partial response, and 17 patients (25.8%) experienced stable disease of > or = 6 months. Median progression-free survival was 5.5 months. Overall, the combination of pertuzumab and trastuzumab was well tolerated, and adverse events were mild to moderate. Cardiac dysfunction was minimal, and no patients withdrew as a result of cardiac-related adverse events.


CONCLUSIONS
The combination of pertuzumab and trastuzumab is active and well tolerated in patients with metastatic HER2-positive breast cancer who had experienced progression during prior trastuzumab therapy.
Baselga
José
J
Vall d'Hebron Institute of Oncology, Vall d'Hebron University Hospital, Paseo Vall d'Hebron 119-129, Barcelona, Spain E-08035. jbaselga@vhebron.net
Gelmon
Karen A
KA
Verma
Shailendra
S
Wardley
Andrew
A
Conte
Pierfranco
P
Miles
David
D
Bianchi
Giulia
G
Cortes
Javier
J
McNally
Virginia A
VA
Ross
Graham A
GA
Fumoleau
Pierre
P
Gianni
Luca
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000009:adverse effects; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D013318:Stroke Volume / Q000187:drug effects; D000068878:Trastuzumab; D016277:Ventricular Function, Left / Q000187:drug effects
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human; C485206:pertuzumab