Mosunetuzumab in Follicular Lymphoma: Durable Responses and Manageable Safety

At the recent American Society of Hematology (ASH) annual meeting, updated data on mosunetuzumab (Lunsumio) in relapsed/refractory follicular lymphoma revealed durable responses, particularly in high-risk patients.

In this first of four exclusive episodes, MedPage Today brought together three expert leaders in the field, all from the Ohio State University Wexner Medical Center in Columbus: moderator Kami J. Maddocks, MD, is joined by Yazeed Y. Sawalha, MD, and David A. Bond, MD, for a roundtable discussion on the long-term follow-up data on mosunetuzumab in follicular lymphoma, as well as strategies for managing infections.

Following is a transcript of their remarks:

Maddocks: Hello and welcome to our ASH 2024 Roundtable on follicular lymphoma. I’m Kami Maddocks from The Ohio State University live here at ASH with my colleagues, Dr. David Bond and Dr. Yazeed Sawalha, both from The Ohio State University to discuss some of the emerging data in follicular lymphoma. We’re first going to start with the mosunetuzumab long-term follow-up.

Dr. Bond, can you tell us a little bit about this study and your thoughts?

Bond: Yeah, so this was follow-up from the phase II study, which led to approval of mosunetuzumab for follicular lymphoma, accelerated approval. So it’s a therapy that we’re using currently in clinical practice now. But this gave updated data from the clinical trial with over 4 years of follow-up to help to better understand the long-term safety as well as the long-term duration of response with the therapy.

So with the follow-up, the median duration of response for the responding patients was 45 months. So I thought that was reassuring to see that the responses appear to be maintained for the most part. And the patients that had complete response [CR], two-thirds of the patients were still in remission at the time of the last follow-up, which was also encouraging.

There was some very limited data on retreatment. So there were five patients retreated that were included, and four of those patients that had a complete response. So again, small numbers, but also encouraging that because it’s a time-limited therapy, that this is something that could be given again as a retreatment.

As far as the safety data, I thought it was also interesting to see the recovery of B cells were observed in the patients that had complete response that had stopped therapy. So it’s important and reassuring. And we know infections are a problem with any B cell-directed therapy and the bispecific antibodies included. And on that study included, they saw 20% of patients had serious infections. It still is a concern, and I think we’re learning more about that and have now more standards for prophylaxis that we can include. But I think important data overall.

Maddocks: OK. Dr. Sawalha?

Sawalha: Yeah, I think the data was very reassuring to see a CR rate around 60% of patients and then durable CR with this follow-up in two-thirds of these patients. They also looked at the subset of patients with POD24 [disease progression within 24 months from the start of first-line therapy] — we know these are the high-risk patients — and reassuringly these patients did as well actually as those with late relapses. So that’s very reassuring to see that these bispecifics, these bispecific antibodies in mosunetuzumab in particular here do work in high-risk patients.

As my colleague David mentioned, with the risk of infection that’s now… I think a lot of people are talking about it for good reasons because we’ve seen that this can be an important complication with these bispecific antibodies.

I thought it was kind of interesting to see that most of these infections are occurring early in the first few cycles after treatment, and that was good to see, that the B-cell recovery happened around a year and a half or so from starting treatment. So that gives an advantage with these time-limited treatments in indolent diseases like follicular lymphoma.

Maddocks: Any recommendations, what you’re doing in your practice as far as you mentioned prophylaxis, infection prophylaxis for these patients?

Bond: So I think antiviral prophylaxis, and then also pneumocystis prophylaxis are something that we’re standardly using, recognizing that at least that’s two of the opportunistic infections that you can see. And then just having a high degree of vigilance for other less common opportunistic infections early on.

Sawalha: I agree. And then the importance of vaccination as well, especially during this time of the year.

Maddocks: Are you looking at immunoglobulin levels in these patients or only if they have issues?

Bond: I think it’s worth following. Certainly if the patients have recurrent infections and hypogammaglobulinemia, IVIG [intravenous immunoglobulin] administration is indicated and then it’s something to consider even for patients that have severe hypogammaglobulinemia, especially particularly in the winter months.

Maddocks: And this is a fully outpatient fixed-duration therapy, making it nice and convenient for patients?

Sawalha: Correct. So most patients will just get the eight cycles. Very few patients, if any, will be admitted for management of cell toxicity. So very convenient, which can add to the benefit from these treatments for sure.

Maddocks: OK, great. Well, thank you guys for the discussion on this abstract.

Sawalha: Thank you.

Bond: Yeah, thank you.

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