ANTIBODIES loaded with radioactive isotopes have completely banished tumours
in scores of patients with a fatal form of the blood cancer non-Hodgkin鈥檚
lymphoma. Tumours shrank in 74 of the 76 patients receiving the antibodies and,
three or more years after treatment, were undetectable in 58
patients鈥攖hree-quarters of those treated.
Mark Kaminski and Richard Wahl of the University of Michigan Comprehensive
Cancer Center in Ann Arbor reported their findings last month at a meeting of
the American Society of Clinical Oncology in New Orleans. 鈥淭he tumours continued
to shrink after therapy,鈥� says Wahl. 鈥淲e saw complete remissions within
尘辞苍迟丑蝉.鈥�
The 鈥淏exxar鈥� mouse antibodies used by Kaminski and Wahl are loaded with
radioactive iodine-131 and exclusively targeted to CD20, a protein found only on
the surface of the B lymphocytes of the immune system. These are the cells that
turn cancerous non-Hodgkin鈥檚 lymphoma, so the antibodies bind to the lymphoma
cells and attack them.
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Some cells are killed by the radiation, but the antibodies also stimulate the
patient鈥檚 immune system. 鈥淪ome normal B cells are killed as well,鈥� says Wahl.
But these will regenerate from stem cells in the bone marrow, which are not
attacked by the antibodies. The researchers can tailor the dose to each patient
by measuring beforehand how fast they can clear radiation.
Because some forms of non-Hodgkin鈥檚 lymphoma progress slowly, further trials
will be needed to ensure the therapy is long-lasting. Side effects were much
milder than with conventional chemotherapy. But 62 per cent of the patients
developed immune reactions against the mouse antibodies, which might rule out
repeat treatment.