Tositumomab and Iodine I 131 Tositumomab (the BEXXAR® Therapeutic Regimen) Shows Efficacy in Elderly Patients (pts) with Relapsed/Refractory Low-Grade (LG), Follicular, and Transformed Non-Hodgkin’s Lymphoma (NHL).
Authors: Gregory Stephanie A. , Zelenetz Andrew , Knox Susan J. , Vose Julie , Leonard John P. , Kaminski Mark 
Published: October 2019

Objective: Pts are first diagnosed with NHL at a median age of 60 yrs. There is increasing support for the idea that physicians should evaluate older pts for cancer treatment on the basis of their health status and cognitive function rather than on chronologic age. Five core clinical trials and an expanded-access program included 995 pts with relapsed/refractory LG follicular or transformed NHL treated with BEXXAR. Data were analyzed to establish the efficacy and safety of BEXXAR as a function of age. Safety data have been presented previously (Gregory et al. Blood. 2003;102. Abstract 1485). Overall toxicity and acute hematologic toxicity associated with BEXXAR in older pts is similar to that observed in pts ≤60 yrs.

Methods: BEXXAR efficacy was analyzed by age: group 1 pts, ≤60 yrs (n=586); group 2 pts, >60–≤70 yrs (n=250); group 3 pts, >70 yrs (n=159). Median age at time of BEXXAR was 58 yrs (range, 21–88 yrs). Inclusion criteria included KPS ≥60, platelet count ≥100,000/mm3, ANC ≥1,500 cells/mm3, bone marrow involvement ≤25%, and no impaired renal, hepatic, or cardiac function.

Results: All 3 pt groups had received multiple therapies for NHL before receiving BEXXAR (1–3 prior treatments, 63%–65%; ≥4 prior treatments, 34%–37%). In addition to the known poorer prognosis with older age, pts in groups 2 and 3 more frequently had other poor prognostic features, ie, transformed histology and prior radiotherapy (P <.001). Complete response rates (CR+CCR) to the most recent pre-BEXXAR therapy decreased with increasing age (group 1, 21%; group 2, 12%; group 3, 7%), and progressive disease as the initial “response” to prior therapy increased with age (group 1, 20%; group 2, 29%; group 3, 33%). Table 1 shows response rates and CR post- BEXXAR for the 3 groups.

Post-BEXXAR CR+CCR rates were higher for pts in every age group compared with CR rates to prior therapy. These rates were nearly doubled for pts >60–≤70 yrs (23% vs 12%) and tripled for pts >70 yrs (23% vs 7%).

Conclusions: Of all previously treated pts >60 yrs, ≥50% achieved a response post-BEXXAR. Nearly 25% of pts >60 yrs achieved a CR, with a median duration of CR of 32.3 mos. Response rates and durations of response are somewhat better in younger pts than in pts >60 yrs, but pts >60 yrs presented with poorer prognostic features (as above). Overall toxicity and acute hematologic toxicity associated with BEXXAR in older pts is similar to that observed in pts ≤60 yrs (Gregory et al. Blood. 2003;102. Abstract 1485). BEXXAR can be administered safely and effectively to older pts with low-grade follicular or transformed NHL.

Table 1 Response results to BEXXAR by age, N = 995

Age groups Overall response, % CR, % Median CR duration, mos ≤ 60 66 37 59.1 (n=586) 95% CI = 45.8, NR) 60 to ≤70 N = 250 50 23 21.8 (n=250) (95% CI = 15.7, 69.1) >70 54 23 36.4 (n=159) (95% CI = 22.6, NR)