SWOG S0016, which compared treatment with CHOP-R (cyclophosphamide, doxorubicin, vincristine, prednisone, plus rituximab [Rituxan]) and CHOP-RIT (CHOP plus tositumomab/iodine-131 tositumomab [Bexxar]) in patients with follicular lymphoma, was one of the most important studies at the 2011 ASH meeting, Andrew Zelenetz, MD, of Memorial Sloan-Kettering Cancer Center, New York, told The ASCO Post.

“The finding that these two treatment approaches are similar tells us that a single course of radioimmunotherapy can replace multiple doses of rituximab,” he said. But the study failed to answer the questions that are most relevant for today’s population of follicular lymphoma patients, he said, and other specialists agreed. “What would the outcome be if we added radioimmunotherapy to CHOP-R? That’s the key question,” according to Dr. Zelenetz.

Other Concerns

Mark S. Kaminski, MD, of the University of Michigan Health System, Ann Arbor, elaborated. “The presentations in this session illustrate something in the back of our minds,” he said. “We are adding more and more treatment to these patients as we go along—not just chemotherapy, but radioimmunotherapy and maintenance. This is despite data showing that radioimmunotherapy as a single agent that takes only 2 weeks to deliver results in very long remissions in the majority of patients. I am concerned that we have swung the pendulum so far in one direction that we can never conduct a trial that will compare this single approach with what has become the current standard.”

In his presentation, lead investigator Oliver Press, MD, of the Seattle Cancer Care Alliance, agreed on the need to evaluate strategies such as as CHOP-R followed by rituximab maintenance, CHOP-R followed by radioimmunotherapy, or CHOP-R followed by radioimmunotherapy followed by rituximab maintenance. Some of these studies are underway, he noted.

The First-Line Indolent (FIT) Trial reported at ASH in 2007 and subsequently published¹ concluded patients could receive chemotherapy with rituximab (CHOP-R), followed by adjuvant radioimmunotherapy (⁹⁰Y-ibritumomab tiuxetan [Zevalin]). This trial led to approval of  ibritumomab tiuxetan in previously untreated follicular NHL patients who achieve a partial or complete response to first-line chemotherapy.

“I think it is still valuable to think about radioimmunotherapy as a front-line treatment, even as monotherapy, and also in terms of the order in which it may be given with chemotherapy,” Dr. Kaminski added. “Perhaps there is another question to ask: What is the optimal schedule for radioimmunotherapy? Should it come before or after chemotherapy? For instance, we could use a very powerful agent upfront, like radioimmunotherapy, and the ‘cleanup’ could be with minimal chemotherapy.” ■

Disclosure: Dr. Zelenetz was involved in the initial trials leading to the approval of tositumomab/I¹³¹-tositumomab and is a consultant to GlaxoSmithKline, the manufacturer of tositumomab/I¹³¹-tositumomab. Dr. Kaminski has patents on CD20 radioimmunotherapy and receives research funding from GlaxoSmithKline.

Reference

1. Morschhauser F, Radford J, Van Hoof A, et al: Phase III trial of consolidations therapy with Yttrium–90–ibritumomab tiuxetan  compared with no additional therapy after first remission in advanced follicular lymphoma. J Clin Oncol 26:5156-5164, 2008.