PET-Guided Therapy for Aggressive Non-Hodgkin Lymphomas
In a German phase III trial (PETAL) reported in the Journal of Clinical Oncology, Dührsen et al found that interim 18F-FDG positron emission tomography (PET) findings were associated with survival in patients with aggressive non-Hodgkin lymphomas receiving R-CHOP (rituximab [Rituxan] plus cyclophosphamide, doxorubicin, vincristine, and prednisone), and that PET-based treatment intensification did not improve outcome.
Study Details
In the trial, a total of 862 patients with newly diagnosed aggressive B-cell or T-cell lymphomas enrolled between November 2007 and December 2012 underwent interim PET scanning after two cycles of CHOP (R-CHOP in patients with CD20-positive lymphomas). Patients with a positive scan were randomized to receive six additional cycles of R-CHOP or to six blocks of an intensive methotrexate- and cytarabine-based regimen (Burkitt protocol). PET-negative patients with CD20-positive lymphomas were randomized to receive four additional cycles of R-CHOP or the same treatment with two additional doses of rituximab. Positive interim scans were infrequent among screened patients, resulting in slow recruitment; in December 2012, the data and safety monitoring board recommended the termination of recruitment since the recruitment goal was unlikely to be reached and since the Burkitt protocol was observed to be more toxic and potentially less effective than R-CHOP.
The primary endpoint was event-free survival.
Treatment Outcomes
Interim PET was positive in 108 patients (12.5%) and negative in 754 (87.5%). Among PET-positive patients, 52 received R-CHOP and 56 the Burkitt protocol; 2-year event-free survival rates were 42.0% vs 31.6% (hazard ratio [HR] = 1.50, P = .1229), with the Burkitt protocol producing substantially greater toxicity. Among the 754 PET-negative patients, 255 were randomized to R-CHOP (n = 129) or R-CHOP with additional rituximab (n = 126). Two-year event-free survival rates were 76.4% vs 73.5% (HR = 1.048, P = .8305). Prognosis according to interim PET findings was independent of prognosis according to the International Prognostic Index. Findings among patients with diffuse large B-cell lymphoma were similar to those in the total patient group.
The investigators concluded, “Interim PET predicted survival in patients with aggressive lymphomas treated with R-CHOP. PET-based treatment intensification did not improve outcome.”
The study was funded by Deutsche Krebshilfe, Amgen Germany, and Roche Pharma.
Ulrich Dührsen, MD, of the Department of Hematology, University Hospital Essen, is the corresponding author for the Journal of Clinical Oncology article.
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