Phase II study of short course CHOP-rituximab followed by 90-y ibritumomab tiuxetan as first-line treatment for follicular lymphoma: Extended follow-up and predictors of relapse.

Abstract

8066 Background: We previously reported complete response rate (CR) of 89% in 60 patients with stage II-IV symptomatic or bulky follicular lymphoma(FL) who received a short-course CHOP-rituximab (R) × 3 cycles followed by ibritumomab tiuxetan (IT) and extended R as first-line treatment. (Clin Cancer Rsrch. 2008;14(21):7088-7094) This abstract will update the response rate at median follow-up of 45 months (range 30-60 months). Methods: Determination of response and duration of response included a fusion [18F] fluorodeoxyglucose (FDG)-positron emission tomography (PET)-computed tomography (CT) imaging performed at baseline, after the third cycle of CHOP-R, 12 weeks after RIT, then at 6-month intervals for the first three years, and then yearly or at physicians' discretion. Results: Of the 60 enrolled patients, 55 completed all protocol therapy. 54 patients are available for evaluation. The CR rate for all enrolled patients by PET-CT is 59%. To date, 22(41%) patients have relapsed at 7.8-55 months. Of the 32 patients with bone marrow involvement, 17 patients had relapses, while of the 22 patients with no bone marrow involvement, only 5 relapsed. 20 of 36 patients with bulky disease have relapsed compared to 2 of 18 patients with non-bulky disease. 9 of 18 patients (50%) with a positive PET scan after CHOP-R have relapsed compared to 13 relapses of 36(36%) patients with a negative PET scan after CHOP-R. 12 of 25 (48%) patients with FLIPI score ≥3 have relapsed compare to 10 of 29 patients (34%) with FLIPI score <3. Six patients have been diagnosed with a second malignancy. None of the patients developed myelodysplastic syndrome or acute myeloid leukemia. Conclusions: Short course CHOP-R followed by IT and extended R results in high CR rate. After median follow up of 45 months, 59% patients still remain in clinical remission. However, despite achieving a CR after initial therapy, positive bone marrow involvement (p=0.03) and bulky disease (p<0.001) at baseline are predictive of relapse. Further evaluation of the molecular marker, Fc gamma receptor genotyping, is planned as potential predictor of outcome. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Zevalin