Most of us are familiar with Herceptin – the medicine that transformed the treatment of HER2-positive breast cancer in the early 2000s. Herceptin is the brand name for this drug which is supplied by pharmaceutical company Roche. Trastuzumab is its generic name.
Roche’s patents on Herceptin/trastuzumab expired in Europe in 2014 and in the United States in 2019. Now a number of copies of this medicine – called trastuzumab biosimilars – have been developed by other companies and are on the market. With several competing products available, their prices are highly likely to be lower than for the original drug.
Trastuzumab is a ‘biologic’ medicine – it is a monoclonal antibody which has to be grown in a living cell culture system, rather than a drug that can be produced by a purely chemical reaction. When a new company wants to produce a copy of a biologic medicine, it will develop its own biological system to ‘grow’ the medicine. This system could be different from the original one, and the final product will be highly similar but not identical to the original. Hence the term ‘biosimilar’.
Before it comes to market, each product is tested to ensure that it works as well and is as safe as the original. When granting approval for use in New Zealand, Medsafe uses the same evaluation procedure as the European Medicines Agency. This includes looking at the pharmacodynamics (what the drug does to the body) and pharmacokinetics (what the body does to the drug) of each biosimilar compared to the original. Data from laboratory experiments and clinical trials are evaluated. Suppliers must also submit results from immunogenicity tests – these are important for determining if it will be safe for patients already being treated to be switched to the biosimilar (‘interchangeable’ drugs).
In New Zealand, suppliers are getting ready for a call from PHARMAC to supply a trastuzumab biosimilar. PHARMAC’s Annual Procurement Plan, published in March 2020, suggests that a request for tenders for trastuzumab could be issued between October and December 2020.
So far, Medsafe has approved or is evaluating several trastuzumab biosimilars: Ogivri (supplied by Mylan), Trazimera (supplied by Pfizer), Herzuma (supplied by Celltrion), and Kanjinti (supplied by Amgen). Herclon, a version of Herceptin produced in India by Roche, is also under evaluation.
PHARMAC is currently assessing an application from Celltrion to have Herzuma publicly funded. In May 2020, PHARMAC’s clinical advisors reviewed the evidence and decided that it would be clinically acceptable to use a trastuzumab biosimilar like Herzuma instead of Herceptin. They recommended that PHARMAC undertake a competitive process to consider several trastuzumab biosimilars at once and see which supplier could offer the best deal.
In Australia, Herceptin, Herzuma, Kanjinti, Ogivri, Trazimera and Ontruzant (from Merck Sharpe & Dohme) are all subsidised by the government and available in the public system. Trastuzumab biosimilars have been approved and used in Europe, the United States and England since 2018.
“As long as trastuzumab biosimilars are as effective and safe as the original product Herceptin, then we would be pleased to see them being provided to New Zealand women with HER2-positive breast cancer” says BCAC Chairperson Libby Burgess. “It’s reassuring that these products have already been rigorously evaluated by overseas regulators, and found to be up to the mark. It would be ideal if we could follow Australia’s example and ensure that there is a choice of products available, in case some patients experience different effects, but PHARMAC has traditionally funded a single product only. The lower price of biosimilars should allow PHARMAC to purchase more medicines with the savings.”
27 July 2020