Pfizer announced positive results from the REFLECTIONS B3271002 study that compared the safety and efficacy of Herceptin (trastuzumab; Genentech) and PF-05280014, a potential biosimilar to Herceptin.

REFLECTIONS B3271002 was a Phase 3 randomized, double-blind study (n=690) that evaluated the safety, efficacy, pharmacokinetics, and immunogenicity of PF-05280014 in combination with paclitaxel vs. Herceptin in combination with paclitaxel in first-line patients with HER2-positive metastatic breast cancer

The study’s primary endpoint was objective response rate (ORR) by Week 25 of study treatment, defined as the proportion of patients with tumor size reduction of a predefined amount and for a minimum period of time. Equivalence in the primary endpoint of PF-05280014 vs. Herceptin taken with paclitaxel was demonstrated in first-line patients with HER2-positive metastatic breast cancer.  

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REFLECTIONS B3271004, a separate randomized, double-blind, comparative study in early breast cancer patients (n=226) also achieved its primary endpoint of steady-state Ctrough concentrations in patients treated with PF-05280014 and Herceptin.

PF-05280014 is a monoclonal antibody being developed as a potential biosimilar to Herceptin for all currently approved indications. Herceptin is also approved to treat HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma, in combination with cisplatin and capecitabine or 5-fluorouracil, in patients who have not received prior treatment. 

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