Front-line treatment for previously untreated follicular B-cell lymphoma with
the iodine-131-labeled anti-CD20 antibody tositumomab (Bexxar) has been
reported to result in a 97% response rate and a 74% complete response rate.
Although the median duration of response has not yet been reached with a median
follow-up of 2.7 years, concerns have been raised over the tolerability of
salvage treatments upon relapse of disease. We have reviewed the clinical course
of the 28 patients that have relapsed among the original group of 76 patients
treated with tositumomab/iodine-131 tositumomab as front-line therapy.
Of 28 relapsed patients (median age, 50 years [range: 28-60 years]), 22
have received some form of treatment and 6 are being observed. For those who
were subsequently treated, the median time from tositumomab/iodine-131
tositumomab treatment to salvage treatment was 321 days (range: 67-1,440 days)
and the median time from relapse to treatment was 104 days (range: 3-775
days). Seventeen patients received at least one chemotherapy regimen at some
point, 12 received rituximab (Rituxan) either alone or in combination with
chemotherapy, 8 received localized irradiation (one as the only subsequent
treatment), and 1 was retreated with tositumomab/iodine-131 tositumomab. The
median number of total regimens received post-tositumomab/iodine-131
tositumomab was 2.5 (range: 1-7).
Of the 17 patients who received chemotherapy, 8 were given 2 or more regimens
(range: 2-5), including 4 patients who underwent stem cell transplants
(2 autologous, 2 allogeneic). All four of these transplanted patients had
received at least three prior chemotherapy regimens. With only one exception, no
patient had treatment discontinued because of blood count intolerance due to a
hypocellular marrow. No difficulties were encountered in stem cell mobilization
or engraftment posttransplant. No cases of myelodysplasia or acute myelogenous
leukemia have been observed to date. There were no adverse effects beyond those
expected in patients treated with rituximab or local irradiation.
CONCLUSION: Front-line tositumomab/iodine-131 tositumomab therapy does not
preclude other treatment options, including those involving myelosuppressive