Potential clinical and financial causes for hesitation in the transition to subcutaneous dosing are addressed.
Adam Brufsky, MD, PhD: In terms of your staff—pharmacy staff, medical staff, or nursing staff—the question I have for you is, have you gotten any pushback or feedback from them about how this is going? Is anybody saying that just with the fear of the unknown, they're afraid to do it? But once they do it, how do they feel? Are they generally OK with it once they start?
Matthew J. Matasar, MD: I think in the medical side there's always a little bit of reluctance, particularly with a medicine like rituximab where it's being used in a lot of different settings with a lot of different reasons. When it's being used in diseases that are being managed, like chronic illnesses such as low-grade B-cell lymphomas where the treatment's not with curative intent, there's a lot more comfort in substituting a subcutaneous for an IV [intravenous] formulation. Contrast that to a disease like diffuse large B-cell lymphoma wheree you're treating with curative intent and where inclusion of intravenous rituximab has been rigorously established as improving overall survival, and there's a much greater reluctance in some settings to make the changeover to using subcutaneous formulations without a stronger body of evidence that substitution doesn't have an impact on survival.
Adam M. Brufsky, MD, PhD: So they're not worried. I thought I saw some studies that there are some at least response rates, head-to-head, that look the same.
Matthew J. Matasar, MD: The response rates look the same. When they've been looked at there's no statistically significant difference between the IV and subcutaneous formulations. We have PK [pharmacokinetics] data to suggest that absorption with the subcutaneous formulation is as good or better, and yet, without a rigorous assessment looking at well powered OS [overall survival] benefit endpoints, I think there is still a natural reluctance among some of the lymphoma community to substitute when Rituxan is being given without curative intent.
Adam M. Brufsky, MD, PhD: Well, that's the whole point. We have the same situation with trastuzumab in breast cancer. You have a drug that likely is going to have a cost delta of I'm guessing 25%, 30%, who knows, versus a branded subcutaneous formulation. How do we make the decision between the 2? Do you have any comments on that from a pharmacy perspective?
Tim Peterson, PharmD, BCOP: I think what's really going to be interesting is when we look at the subcutaneous formulations, their costs, being that they are branded products, is not that far out from intravenous products for rituximab and trastuzumab.
Adam M. Brufsky, MD, PhD: Correct. That's not the issue, it's really the biosimilar that's the issue.
Tim Peterson, PharmD, BCOP: Exactly. So when those come out, it's probably going to be much more of a competitive market when we look at the cost between those different agents where the biosimilars are going to have to adjust to provide more benefit for that extra time in the chair and the extra things that patients have already said, based on these quality of life studies that have been performed for both of these agents. They do prefer subcutaneous administration. And if insurance is covering both of them, it ocmes down to patient preference.