The impact of FLIPI on outcome of frontline treatment with single-agent I-131 tositumomab for follicular lymphoma (FL).

7509 Background: The FLIPI is potentially useful in predicting clinical outcome and comparing treatment results among clinical studies in FL. We recently reported the results of I-131 tositumomab as frontline treatment in 76 pts with advanced-stage FL (NEJM 325:441, 2005). A single 1-week course resulted in a 95% and a 75% overall and complete response (CR) rate, respectively, and at a median follow-up of 5.1 years median progression-free survival (PFS) was 6.1 yrs. In multivariate analyses, bone marrow involvement was the only baseline variable that had a significant effect on PFS. METHODS To evaluate whether baseline FLIPI scores in this study could predict outcome and to compare this pt population with that in other frontline studies, the records of all 76 patients were reviewed. RESULTS FLIPI scores were available for 74 of the 76 pts: 11 pts (15%) low risk, 37 (50%) intermediate risk, and 26 (35%) high risk. CR rates for each risk group were 82%, 73%, and 73%, respectively. 5-yr PFS were 63% (35-92%, 95% CI), 63% (47-78%), and 52% (33-71%), respectively, p = 0.322. Grouping low + intermediate risk vs. high for PFS: p = 0.134. 5-yr overall survival (OS) rates were 100%, 95% (87-100%), 78% (62- 93%), respectively, p = 0.072, but grouping low + intermediate risk vs. high p = 0.028. A comparison to other frontline studies is below. CONCLUSIONS The FLIPI did not predict for PFS or OS in FL pts treated with single-agent I-131 Tositumomab. However, an OS difference was seen when low + intermediate risk pts were grouped and compared with high risk pts. The distribution of FLIPI scores amongst pts in this study is similar to that observed in other front-line FL studies. Further studies exploring single-agent radioimmunotherapy vs. chemo/radioimmunotherapy combinations are warranted. [Table: see text] [Table: see text].