PET Scan After Frontline Therapy for FL


Ian W. Flinn, MD, PhD: I’m hearing various different approaches to the frontline lymphoma, follicular lymphoma, perhaps using an anthracycline type of regimen in patients who have more aggressive disease. These are patients who have demonstrated transformation or suspected transformation, some of that high PET [positron emission tomography] avidity, perhaps single-agent monotherapy in follicular lymphoma in the less fit or even in patients less bulky, and then bendamustine-rituximab for a lot. Does that line up with the way you think about things, Pier Luigi?

Pier Luigi Zinzani, MD, PhD: Absolutely. I’ve been using bendamustine plus rituximab from 2015, and I’m very happy because it’s possible to have very good results in terms of clinical response when you compare with [R-CHOP] [rituximab, cyclophosphamide, hydroxydaunorubicin, oncovin, prednisone] or [R-CVP] [rituximab, cyclophosphamide, vincristine, prednisone]. But at the same time it’s less toxic. This is very important for the patient to avoid, for example, because it could cause nausea and vomiting…. And I use CHOP [cyclophosphamide, hydroxydaunorubicin, oncovin, prednisone] plus rituximab in a selected patient, for example, grade 3a or a young patient with real important tumor burden. But more than 10% of patients, I treat them with CHOP plus rituximab. I don’t use CVP [cyclophosphamide, vincristine, prednisone] plus rituximab. Anyway, in the GALLIUM study, the arm including CVP [cyclophosphamide, vincristine, prednisone] plus obinutuzumab looks quite interesting. It was the best in terms of improvement of CR [complete response] rate and overall response rate, and it was the best when you compare with bendamustine plus obinutuzumab—CHOP plus obinutuzumab. Anyway, BR [bendamustine, rituximab] is the most used chemoimmunotherapy regimen in Europe, in particular Italy, Germany, and Nordic countries and also in Spain.

Ian W. Flinn, MD, PhD: What about post-treatment evaluation after chemotherapy? We talked a little bit about PET scanning before. What about PET scanning afterward, John?

John M. Pagel, MD, PhD: Yeah, I think PET scanning afterward is—again, as I even mentioned earlier—the gold standard to assess the response at the end of treatment. Again, it’s simply because it’s much more sensitive and much more specific than a CT [computed tomography] scan. It’s not required. We recognized that there are advantages to it, but certainly we recognize that there are costs, and for some patients it may not be warranted. But in general, I would say a PET scan at the end of treatment is the standard of what we’re doing now.

Ian W. Flinn, MD, PhD: Matt, what if they’re PET-positive? Are you doing something different in that setting?

Matthew Lunning, DO: Well, it depends upon how PET-positive they are. And I think our radiologists have started to adopt kind of the more contemporary Lugano criteria and [apply] it to follicular lymphoma with a Deauville score at the end. And remembering back to the response rates that are CT based, a lot of patients with follicular lymphoma will have PR [partial response]. So now we’re taking a lot of these people with PET-based therapies, and they’re a metabolic CR but they have residual abnormal nodal size. It’s kind of new territory with regard to that and to know what to do with it. Because on 1 hand, it’s an incurable disease, right? But on the other hand, if their delta SUV [standardized uptake value] isn’t something that is impressive, but it still goes from 6 cm down to 1.8 cm, but the SUV stays at 8, that’s tough to know what to do with.

John M. Pagel, MD, PhD: Yeah, and I’ll just jump in and say it depends on where that lymph node or that lesion is. Because there may be some that we’ll zap with a little radiation and clear that up, and it won’t be a big deal, not a lot of morbidity, and that might be very beneficial to that type of patient. I guess the other question is, do you actually go and do maintenance therapy as a way to continue to consolidate the remission or improve the remission if you see some remaining PET avidity? And I don’t use that typically to say if I’m going to do maintenance therapy or not. I’d be curious if other people do, but it’s probably not a driver for if I’m going to do more of that or not.

Ian W. Flinn, MD, PhD: Before we get to the maintenance question, because I think it’s a long discussion, you brought up an interesting point. That person has an SUV of 8 afterward and perhaps giving it radiation. I guess I worry that that’s different biologically from the rest, so do we need to biopsy that?

Matthew Lunning, DO: Right. And I think the inherent question is, if you do a PET, how soon do you do it after chemotherapy? If it’s an SUV that’s kind of hovering around liver background, that’s different for me from 2 to 3 times liver background and an abnormal lymph node, or it really didn’t move but everything else moved. To me that’s a different biology, and that’s probably the biology that’s going to get that follicular lymphoma patient into trouble in what would be the near future.

Transcript Edited for Clarity

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