Bijal D. Shah, MD, MS: Let’s talk a little bit about marginal zone lymphoma. Interestingly, it’s probably about double the rate of mantle cell lymphoma, though it still has this moniker of a rare B-cell malignancy. If I had to guess, it’s probably somewhere around 8,000 or so cases in the US each year, broken down broadly into 3 subgroups; nodal marginal zone lymphomas, splenic marginal zone lymphomas, and then the constellation of extranodal marginal zone lymphomas, most commonly MALT of the stomach. But also, we can see bronchial-associated marginal zone lymphomas, as well as the orbital marginal zone lymphomas, skin, and so on. One of the things that’s hard to distinguish for me in practice is how we distinguish high-risk from low-risk marginal zone lymphomas. Caron, when we were talking earlier, you said something to the effect of “When I really have to treat them, that’s when I’m worried.” I didn’t know if you wanted to [further elaborate].

Caron A. Jacobson, MD, MPH: That comment was really specific for the nodal marginal zone lymphoma patients which we always sort of clump with follicular lymphoma, but they tend to be a little bit more chemoimmunotherapy resistant. Low-volume disease doesn’t respond as well as to single-agent Rituxan. I’ve tended to see short responses when you add an alkylating agent to that therapy, and so I do get a little bit nervous. They tend to progress much more slowly, and so many of these patients you can watch for a long time. But I do struggle once I have to start treating them. Now, splenic and extranodal marginal zone lymphomas, they tend to respond very well to either radiotherapy or to single-agent Rituxan therapy with minimal toxicity with good benefit in terms of durable response rate, but I do worry about nodal disease when it has to be treated.

Bijal D. Shah, MD, MS: That’s a very good point. Ian, you included marginal zone lymphomas on the BRIGHT study [DOI: 10.1182/blood-2013-11-531327]. You can remind me, this was a follicular, marginal, and mantle if I recall. What are your thoughts when it comes to frontline chemoimmunotherapy with bendamustine or other based approaches?

Ian W. Flinn, MD, PhD: I think that my experience is frankly very similar to Caron’s. For many, many patients with marginal zone lymphoma, you could follow them for a very long time before having to intervene. Then, the treatment choices are relatively similar to follicular lymphoma, right? You’re going to be using chemoimmunotherapies, single-agent rituximab, I guess [I am] speaking about the nodal variant here. But, as Caron mentioned, they’re slow to progress and they’re slow to respond. It seems like it’s moving an iceberg or something. It slowly gets worse and it slowly gets better. I hope that we can watch it for as long as possible before intervening.

Then, as I think Caron also mentioned, therapies for splenic marginal zone lymphoma, still splenectomy is a very reasonable option for those patients, even patients who have disease outside the spleen, that you often get responses for reasons that aren’t completely apparent to me why that happens. But splenectomy is a reasonable option or even single-agent rituximab. Sometimes, patients have such huge spleens, it’s a real surgical mess to take out the spleen when they initially present.

Bijal D. Shah, MD, MS: How do you think about, and I think you alluded to this somewhat, treatment failure in marginal zone lymphoma? You mentioned they were slow to respond. I’m curious then, at what point are you worried? Is it when you actually see the nodal or other sites of disease truly progressing, or are there stable-disease patients where you say, “I’m just not comfortable with that”?

Ian W. Flinn, MD, PhD: I mean, sometimes stable is all you’re going to get and so you get comfortable, but I take your point. I think I still use the classic definitions of progression and response, but, again, just because someone is progressing doesn’t mean I need to do anything about it. Continue to observe people until you’re really forced, especially if the initial response was lackluster, then [decide] what you are going to do for the next response. You also mentioned you can get cytopenias, so that’s another reason to treat or at least to intervene at some point.

Transcript edited for clarity.