BETHESDA, MdLow-grade lymphomas usually respond to initial
chemotherapy but almost inevitably relapse. Each subsequent
chemotherapy regimen produces a shorter response. Research presented
at the American Society of Hematology meeting suggests that this may
not be the case with the anti-CD20 antibody rituximab (Rituxan).
Thomas Davis, MD, of the NCI, and his colleagues reported that about
40% of patients with low-grade or follicular non-Hodgkins
lymphoma who had initially responded to rituximab also responded to a
second round of treatment, and that re-treatment produced response
durations as good as those of initial rituximab therapy.
A Case Study
As an example of the efficacy of rituximab re-treatment, Dr. Davis
The patient received three courses of rituximab, with times to
A fourth course of rituximab has produced an ongoing partial remission.
Rituximab has good efficacy in about half of patients in whom
the real question becomes, how long can you continue to treat with
the antibody and avoid alternate therapies? Dr. Davis said in
an interview. For patients who have low-grade or follicular
lymphoma, survival may ultimately depend on how many different
treatments you can give.
This open-label, single-arm study enrolled 58 patients. All were
treated with one additional course of rituximab (375 mg/m²
intravenously once weekly for 4 weeks), and two patients also
received a third course.
All patients were relapsed or refractory to prior chemotherapy but
had previously responded to rituximab. All had relapsed after
rituximab and required further treatment. In addition to
chemotherapy, 18 patients had received bioimmunotherapy other than
rituximab, and 18 had received radiotherapy.
Dr. Davis reported data from 57 patients who were evaluable for
efficacy. The overall response rate to the second round of rituximab
was 40%. This included complete responses in six patients (11%) and
partial responses in 17 patients (30%). This is in contrast to
patients treated with chemotherapy who typically do not respond to
repeated administration of a regimen once their disease has progressed.
At the time of this report, the median duration of response was 15+
months (range, 2.5 to 25.1 months), and the median time to
progression was 16.7+ months (range, 4.6 to 26.6 months).
There is evidence that for patients who respond to a first
course of rituximab, the duration of response will be longer than the
duration of their response to prior chemotherapy. From this study, we
see that they also respond at least as well to rituximab the second
time around, Dr. Davis said.
The safety profile was similar to that reported for initial treatment
with rituximab, consisting primarily of infusion-related adverse
events usually occurring within the first few hours of the first
infusion. None of the patients developed human antichimeric
The side effects of this treatment are more tolerable than
those of radiotherapy or chemotherapy, so if we can use rituximab
repeatedly, patients should have a better quality of life, Dr.
He advised that patients who have responded to rituximab and relapsed
should definitely be retreated. You may want to consider doing
another fine-needle aspiration biopsy to make sure the tumor still
has CD20 expression and thus has a chance of responding to the antibody.
Experience to date suggests that rituximab does not induce resistance
to subsequent chemotherapy or reduce its efficacy. The benefits
of multiple courses of rituximab include deferring toxic alternative
treatments and preserving marrow function, he said.