The phase III REFLECTIONS B327-02 trial aims to study the efficacy, safety, pharmacokinetics and immunogenicity of Pfizer’s biosimilar (PF-05280014) compared to Roche’s blockbuster breast cancer treatment Herceptin (trastuzumab). The trial is a randomized, double-blind, parallel group, active comparator trial with two groups of patients, one of which will receive the biosimilar and one of which will receive Herceptin. All patients will receive intravenous infusions of either PF-05280014 or Herceptin weekly for 52 weeks or until disease progression.

The purpose of the trial is to compare the efficacy, safety, pharmacokinetics and immunogenicity of Pfizer’s biosimilar (PF-05280014) and to establish the ‘similarity’ of the biosimilar to Herceptin (trastuzumab) in female patients with human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer in the first-line treatment setting.

The primary evaluation of the drugs will be based on the percentage of patients within each treatment group that achieved Complete Response (CR) or Partial Response (PR) by Week 25 of the study (± 14 days) and confirmed on a follow-up assessment, in accordance with the RECIST 1.1.

RECIST (Response Evaluation Criteria In Solid Tumours) is a set of published rules that define when cancer patients improve (‘respond’), stay the same (‘stable’) or worsen (‘progression’) during treatment.

The phase III study is being carried out at 95 centres in the Czech Republic, Hungary, Japan, Korea, Philippines, Poland, Puerto Rico, Romania, Russia, South Africa, Spain, Turkey and the US. The trial is expected to recruit 690 female patients with HER2+, metastatic breast cancer aged 18 years and older. The study started in February 2014 and is expected to be completed in May 2016, according to ClinicalTrials.gov.

The patent on Herceptin expires in 2014 in Europe and in 2019 in the US and the drug could be exposed to biosimilar competition in Europe from 2015. In an attempt to ward off biosimilar competition, Roche is developing its ‘armed antibody’ trastuzumab emtansine (T-DM1) as a successor to Herceptin.

This phase III trial follows on from the successful phase I REFLECTIONS B327-01 study, which demonstrated ‘similarity’ in terms of pharmacokinetic properties for PF-05280014 compared to both trastuzumab sourced from the US and trastuzumab sourced from the EU, and of trastuzumab-US compared to trastuzumab-EU for a single intravenous administration of the drugs [1].

Pfizer also started a phase I/II trial with its biosimilar rituximab candidate (PF-05280586) in March 2012, comparing it to Roche’s rheumatoid arthritis treatment Rituxan/MabThera (rituximab) [2].

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References

1.  GaBI Online - Generics and Biosimilars Initiative. Pfizer carrying out biosimilar trastuzumab trial in US [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2014 Jun 2]. Available from: www.gabionline.net/Biosimilars/Research/Pfizer-carrying-out-biosimilar-trastuzumab-trial-in-US

2.  GaBI Online - Generics and Biosimilars Initiative. Also noted on biosimilars: 11 May 2012. Pfizer starts phase I/II biosimilar rituximab trial [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2014 Jun 2]. Available from: www.gabionline.net/Biosimilars/General/Also-noted-on-biosimilars-11-May-2012

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