Zevalin Efficacy Confirmed in Patients With Relapsed or Refractory NHL
Emma Hitt, PhD
[These results look strikingly good. Do you think that Zevalin will become a serious competitor to Rituxan and other aspiring NHL agents (I am thinking in terms of Velcade in the first place)? Or are the radiation concerns too big to allow a first- or second line treatment positioning?
Erik]
June 4, 2003 (Chicago) — Final results of a pivotal phase III trial presented at the 39th annual meeting of the American Society of Clinical Oncology confirm that yttrium-90 (90Y) ibritumomab tiuxetan (Zevalin) produces high response rates and durable remission in low-grade, follicular, and transformed non-Hodgkin's lymphoma (NHL).
Leo Gordon, MD, chief of hematology/oncology at Northwestern Memorial Hospital in Chicago, Illinois, presented the findings here on Saturday at the 39th annual meeting of the American Society of Clinical Oncology.
In February 2002, 90Y ibritumomab tiuxetan was approved as the first commercially available radioimmunotherapy. The molecule consists of the radioisotope 90Y; ibritumomab, the murine parent of rituximab, which binds CD20; and tiuxetan, which allows for stable in vivo retention of 90Y.
Dr. Gordon and colleagues presented updated information of time-to-event variables from the pivotal, randomized trial of 143 patients with relapsed or refractory low-grade, follicular, or transformed NHL treated with 90Y ibritumomab tiuxetan or rituximab.
In the initial analysis, overall response rate was 80% vs. 56% (P = .002) for 90Y ibritumomab tiuxetan vs. rituximab, and complete response rates were 34% vs. 16% (P = .04), respectively.
The current analysis of mature data involved 29 months of follow-up, and all patients exceeded the Kaplan-Meier estimated median time to progression (TTP), duration of response (DR), and time to next lymphoma therapy (TTNT).
In the study population overall, TTP was 10.6 months in the 90Y ibritumomab tiuxetan group compared with 10.1 months in the rituximab group; DR was 13.9 months vs. 11.8 months, and TTNT was 17.6 vs. 12.4 months, respectively.
When the researchers analyzed the subgroup of patients with follicular NHL, they found that the differences between the 90Y ibritumomab tiuxetan and rituximab treated patients were even more apparent.
Among patients with follicular disease, which accounted for more than three quarters of the patients, TTP was 15.0 months compared with 10.2 months; DR was 16.7 months vs. 11.2 months, and TTNT was 21.5 vs. 13.1 months in the 90Y ibritumomab tiuxetan vs. rituximab groups, respectively.
The researchers note that median DR with 90Y ibritumomab tiuxetan in patients with complete response approaches two years (23 months overall and 26 months in follicular only) and ongoing responses of more than four years' duration have been achieved.
"This study gives us more follow-up information on patients treated with Zevalin, and it highlights the group of patients with follicular lymphoma who have achieved a complete remission with Zevalin," Dr. Gordon told Medscape. "...[It] shows that at the least the trend is that they have a longer duration of complete remission compared with Rituxan alone," he said.
Dr. Gordon emphasized, though, that the study was not initially powered to demonstrate differences in time-to-event variables, "but the trend for patients with follicular NHL is pretty striking," he said.
ASCO 39th Annual Meeting: Abstract 2315. Presented June 1, 2003.
Reviewed by Gary D. Vogin, MD
medscape.com|-3561698683231489368/184161392/6/7001/7001/7002/7002/7001/-1 |
