Biosimilar Trastuzumab in HER2-Positive Breast Cancer

Transcript:Adam M. Brufsky, MD, PhD: Briefly before we move on to another topic, there is data that’s being presented at this ASCO meeting on biosimilar trastuzumab (MYL). I don’t even know if you can call it trastuzumab. Are you allowed to call it biosimilar trastuzumab? Biosimilar, anti-HER2 therapy. I’m not sure what to call it.

Sunil Verma, MD, MSEd, FRCPC: It is biosimilar trastuzumab. So, at the present time, the best way to describe it is a proposed biosimilar. I’m discussing it, and I’ve been reading a lot about biosimilars as a result. It’s interesting; the evaluation of biosimilars really involves three big steps. One is a clinical quality attribute evaluation. That is, does this molecule actually look like the parent molecule, the reference molecule? And there were hundreds and hundreds of tests to be able to actually confirm that. The second is all the pharmacokinetics, pharmacodynamics, and the toxicology. And a third is a covalent study.

So, what the group is presenting is covalents data that shows that this is, at least with respect to response rate, equivalent to in a double-blind, randomized, phase III setting to a reference trastuzumab (Herceptin) compound. Whether that is sufficient to be able to be a stamp of biosimilarity by regulatory bodies remains to be seen because they have to assess the quality attributes, they have to address the pharmacokinetics data, and then they have to take a look at the clinical equivalence. The challenge of biosimilars is the following:

What is a label? Is a label just for metastatic first-line treatment as the study was conducted? Or is it going to be for any indication for trastuzumab to date, including early stage and gastric cancer, as well? We don’t know. Then, the other challenge, of course, is going to be, what about combination with other therapies? Can we combine it with pertuzumab? Can we combine it with other chemotherapies? Because this trial was just based on taxanes.

Adam M. Brufsky, MD, PhD: But it was equivalent?

Sunil Verma, MD, MSEd, FRCPC: It was equivalent.

Adam M. Brufsky, MD, PhD: Could you explain the trial just for our audience?

Sunil Verma, MD, MSEd, FRCPC: Yes. So, the trial was just taxane plus Herceptin versus taxane plus this compound, MYL compound. Can we then extrapolate that data? We don’t know. Since we’re in a new territory…

Adam M. Brufsky, MD, PhD: And the PFS was equivalent, it was about 12 1/2 months, something like that.

Sunil Verma, MD, MSEd, FRCPC: Well, for the PFS at 24 weeks, they just gave the proportion of events that took place; they didn’t actually give a PFS value. We just have a proportion of events. I think it’s going to lead to a lot of discussions. There’s no doubt that we need biosimilars. There’s at least 11 other biosimilars being studied for Herceptin alone—and I have to use the brand name in this case—and there’s 11 other biosimilars that are being studied. And this data suggest that if we integrate biosimilars at the rates that we do need to, it’s going to save the United States government $44 billion over the next 10 years. And it’s the new generation of targeted therapies, immunotherapies, coming off.

Adam M. Brufsky, MD, PhD: That assumes though, Sunil, that the biosimilars are going to be priced less. Do we really know that?

Sunil Verma, MD, MSEd, FRCPC: So, the data in Europe where they have more biosimilars for erythropoietin agents, they have more biosimilars for Neupogen and GCSF (granulocyte colony stimulating factor). And they have Remicade/Inflectra biosimilars, which have shown that the rates of the product decreases by an average range of 20% to 40%.

Adam M. Brufsky, MD, PhD: That’s great. That’s really spectacular.

Sunil Verma, MD, MSEd, FRCPC: I think there is definitely a role, but I think we will have to do a lot of decision making to say, how do we then take this data and put into clinical practice and with which indication?

Adam M. Brufsky, MD, PhD: Good. That’s good.

Transcript Edited for Clarity