Cardiac Toxicity of Biosimilars in Breast Cancer

As biosimilars continue to be pushed in to the oncology space, it is important to prove that they are not only efficacious, but safe as well, explained Hans-Christian Kolberg, MD.

Kolberg, head of the Department of Obstetrics and Gynecology, the Breast Cancer Center, and the Gynecologic Cancer Center at Marienhospital Bottrol in Germany, was recently involved in a study that examined the cardiac toxicity of ABP 980, a trastuzumab (Herceptin) biosimilar in women with HER2-positive, early-stage breast cancer who were involved in the LILAC study.

Oncology Nursing News: Can you give an overview of your research?

Kolberg: Cardiac safety is very important regarding biosimilars because they are not completely the same, but they have more or less the same efficacy in the predefined boundaries of the originator. Because of quotas, people have to use them, so it's very important to do a lot more safety work in that field because people have to have confidence that this is really safe. Efficacy is one thing, but the other thing is that if replacing a standard that you're working with for years now, or almost decades, if it's worth replacing it, and if it's really safe. Saving money is, of course, important regarding healthcare economics, but it also has to be safe.

We showed here that the cardiac events were completely the same. We had no higher cardiac event rate in the arm that stayed completely on the biosimilar, nor on the switching arm. So, we are sure that regarding cardiac safety that this is a safe approach.

What would you say are the implications of these findings for patient and provider confidence in using the biosimilar in markets for which it's approved?

It is very important to keep reporting these things because even people who have been [working in] oncology for years and decades, it is still very difficult to really differentiate between a generic medication and a biosimilar. A generic is simply like cooking the same recipe and developing a biosimilar is completely different. It's really developing a new medication. You just do it the other way around. It is reverse-engineered because you have to find out what the original company was doing.

The effect regarding healthcare economics is that first you can sell that [biosimilar] cheaper because developing a new antibody is an investment of more than $1 billion, usually, whereas developing a biosimilar for a known antibody costs around about $200 million. So, then the prices in the end are cheaper, which is, of course, important in countries like the United States, or Germany, where I work, because we save money and we can use it for other things in the healthcare system. But it's even more important in places where giving a patient an antibody is not a question because there's no money for that, like in the developing countries. And for those, biosimilars may be a huge chance to gain access to antibodies at all.

Of course, we're doing this because it's making healthcare cheaper. But to come back to your question, people have to have confidence that what they're doing is safe. So, every signal we can report that this is a safe therapy, especially [when it comes to] cardiac safety, which is the main issue with Herceptin. People are not replacing a cheaper drug that is not safe enough. I think this will give people confidence.

The second thing is regarding registration and the authorities, biosimilars are always looked at with a so-called totality of evidence approach. Authorities are looking at every signal that is coming (clinical signal, safety signals, pharmacokinetics, pharmacodynamics) a lot closer than they're doing for originators, which is, of course, understandable. An originator is a new chance that you didn't have before. A biosimilar is basically doing the same that the originator did, so it has to be looked at more closely because people have to be completely sure that this is really doing the same and not harming the patient. Papers like what we presented are something that give confidence.

Can you talk about real-world data collection efforts that are underway for the biosimilar?

Real-world data are something that are needed. For the companies selling biosimilars, real-world data are after sales services. So, it's very difficult to get funding for that. We are, at the moment, planning a real-world study on cardiac safety. We are trying to predict cardiac safety with early endpoints, drawing blood after 2 cycles of the biosimilar and the antibody and then trying to measure in the blood biomarkers that may predict cardiac failure in patients.

This is a classical real-world study, and this is very important because the cardiac signals in trastuzumab trials have been decreasing over the years, which is not because trastuzumab is less cardiotoxic, it is because people are more aware of cardiac toxicity, and of course the inclusion and exclusion criteria that have been developed are more strict. So, we may ask ourselves, 'Is this really real world that we're seeing?' And this is why we believe in doing a real-world study.

We found a sponsor for that study. It's very important to include all patients. All patients who are real-world candidates for trastuzumab in a safety study, and not only from a clinical registration trial, where, of course, inclusion/exclusion criteria are designed so you are safe for ethical reasons.