What is a biosimilar and how does it affect you?

We all know that cancer drugs cost a fortune, but did you know there could be cheaper alternatives?

When a drug patent expires new versions come onto the market, increasing competition and lowering the price. But are these drugs as good as the original, do they have different side effects and could they reduce the cost to the Kiwi health system?

There are two types of drug mimicry – generics and biosimilars. Generics are copies of a traditional chemical drug, for example, aspirin, which has multiple generic versions. In contrast, biosimilars are copies of more complex drugs called biologic drugs. Herceptin is an example of a biologic drug used for breast cancer. The first biosimilar was introduced to New Zealand in 2012 - filgrastim - a medicine used to boost white blood cell counts in cancer patients undergoing chemotherapy.

Pharmaceutical companies wishing to create biosimilar products once a patent has expired have no idea of the original manufacturing process, meaning they have to be very careful. In New Zealand Medsafe require a biosimilar drug to have ‘demonstrated comparable quality, safety and efficacy to an approved biologic medicine’.

A huge review compared ninety international biosimilar studies, involving 14,225 individuals. This publication further reassured health care professionals and the public that patients have a ‘low risk of either a safety concern or a loss of efficacy after switching to a biosimilar.’ There was also a concern that biosimilars might trigger an immune response in patients, however, biosimilars have been shown to have a low risk of interfering with the immune system and have what is known as ‘low immunogenicity.’

But how do biosimilars affect breast cancer patients?

The patent on Herceptin has recently expired, meaning that new, cheaper versions are now being produced. You may ask whether this will change the side effects or efficacy of Herceptin. However, clinical trials in women with early breast cancer have shown that the biosimilars are as effective with similar side effects and low immunogenicity.

Biosimilars hold great potential for our health system. They would reduce the money we spend on cancer drugs, thus increasing the remaining budget for new, or currently unfunded medicines. As drug access in New Zealand becomes more serious we may see the rise of the biosimilar.