Clinician resistance is the key obstacle to the successful introduction of a biosimilar drug, and doctors' acceptance of one biosimilar does not mean that others will automatically follow, an industry meeting has heard.

Clinicians' reluctance to using biosimilars (generic versions of off-patent biologic drugs) can be due to a number of reasons, according to Dr Anthony Grosso, formulary pharmacist and QIPP lead at University College Hospitals London (UCHL) NHS Foundation Trust. For example, doctors are concerned at the lack of data underpinning claims made for these products, and of experience with their use; without this evidence to show that they can improve patient care, the mere fact of a lower price than that of the originator product will not be enough to persuade them to switch, he said. There is also a lot of misinformation around, Dr Grosso added, speaking at a meeting of the Pharmaceutical Marketing Society (PMS) in London recently.

Moreover, doctors may be reluctant to switch because of concerns about potential effects on their relations with the manufacturer of the originator product, with whom they may have built close and established relationships as a result of working with the original biologic drug. 

They may also be very happy with the status quo, he said.

Drug and therapeutic committees are, in contrast, "generally positive" about the use of biosimilars, while the main decision-making bodies within the NHS are buying into the concept of newer products - "and we're not too concerned whether this is a biosimilar or a new biologic product," Dr Grosso told the meeting.

But adoption of generic versions of biologic drugs is proving to be entirely product-specific and each challenge has been different, he said. So far, the most successful product has been biosimilar filgrastim, the granulocyte-colony stimulating factor (G-CSF), which has won the backing of all stakeholders. Its lower price has expanded access, enabling wider use and earlier treatment - "we are seeing the benefits at ground level," said Dr Grosso.

But, he added: "we do not have a blanket policy on biosimilars." Nor does he expect to see these products being adopted by blanket review; over the next five years the process will be indication by indication, he said, and consensus among clinicians will be essential.

The biggest challenge will come with the introduction of the first biosimilar monoclonal antibodies (MAbs), expected in 2013. "We've had tentative discussions - we know that they are coming so we are keen to have the system in place. But biosimilar MAbs will be much more complex, we will need greater incentives to use them and there will be more hurdles than we have with the products that are on the table now," he forecast.