Positron emission tomography (PET)-directed approach to therapy shows promise for patients with diffuse large B-cell lymphoma (DLBCL), according to results from a phase 2 clinical trial published in the Journal of Clinical Oncology.

The trial was the prospective National Clinical Trials Network S1001 study (ClinicalTrials.gov Identifier: NCT01359592), which included 132 patients with nonbulky (<10 cm) stage I/II untreated DLBCL. Patients were treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) for 3 cycles and then evaluated by interim PET/computer tomography scan (iPET). Deauville scores of 4 or 5 were considered to be positive in iPET analysis.

An additional cycle of R-CHOP (R-CHOP x 4) was administered to patients with negative iPET scans. Patients with positive iPET scans received further treatment with involved field radiation, rituximab, and ibritumomab tiuxetan.

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Median study follow-up was 4.92 years (range, 1.1-7.7). Patients had a median age of 62 years, and 62% of patients had stage I DLBCL. A total of 128 patients completed iPET scans; 11% of completed scans were positive and 89% were negative.

The estimated 5-year progression-free survival (PFS) rate was 87% (95% CI, 79%-92%), with an estimated overall survival (OS) rate of 89% (95% CI, 82%-94%). For iPET-positive patients, the 5-year PFS rate was 86%, and the 5-year OS rate was 85%. For iPET-negative patients, the 5-year PFS rate was 89%, and the 5-year OS rate was 91%.

Deaths were attributed to lymphoma in 3 patients and to nonlymphoma causes in 11 patients. The study investigators reported that only 6 patients in this study showed disease progression. Of these, 4 had been iPET negative, 1 had been iPET positive but chose not to receive radiation, and 1 had discontinued treatment after 1 cycle.

The study investigators determined that with this PET-directed therapy approach, outcomes were favorable for patients in both the iPET-positive and iPET-negative treatment groups.

“[T]he findings of our study have established that R-CHOP x 4 is a new standard, less morbid approach in limited-stage DLBCL for the absolute majority of patients, reserving radiation for the small subset of patients with interim PET-positive disease.”

Disclosure: Some of the authors disclosed financial relationships with pharmaceutical companies and medical device manufacturers. For a full list of disclosures, please refer to the original study.


Persky DO, Li H, Stephens DM, et al. Positron emission tomography–directed therapy for patients with limited-stage diffuse large B-cell lymphoma: results of Intergroup National Clinical Trials Network Study S1001 [published online July 13, 2020]. J Clin Oncol. doi: 10.1200/JCO.20.00999