LOS ANGELES--Use of a radiolabeled monoclonal antibody in patients
with relapsed B-cell lymphoma may allow higher doses of radiation
to the tumor and less toxicity to normal organs, Oliver W. Press,
MD, PhD, of the University of Washington Medical Center, Seattle,
said in his ASCO presentation.
In this NCI-funded phase II trial, the CD20 antibody, known as
B1 (supplied by Coulter Corporation, Miami), was conjugated to
high doses of iodine 131 (345 to 787 millicuries). After a therapeutic
dose given by injection, patients received either peripheral blood
stem cell or bone marrow support.
Of 25 patients enrolled in the study, all with B-cell lymphoma
expressing CD20 that had relapsed after at least one round of
conventional chemotherapy, 22 exhibited favorable localization
of the radiation to tumor sites after a test dose, and 21 received
a therapeutic dose.
Seventeen patients had a complete response, and 16 have remained
progression free for up to 3 years. At a median follow-up of 1
year, overall survival is 93% and progression-free survival is
All patients had severe neutropenia and thrombopenia; there was
one fatal infection and one serious case of cardiopulmonary toxicity.
"Nevertheless, short-term toxicity was less than we have
experienced in Seattle with our conventional transplant regimens,"
Dr. Press concluded that the radiolabeled antibody when given
at the maximum tolerated dose produces a high response rate with
many responses of long duration, but stressed that further follow-up
is needed to determine response durability and long-term toxicity.