Enhancement of monoclonal antibody binding to melanoma with single dose radiation or hyperthermia.

We undertook this study to determine whether radiation (10 Gray, single dose) or water bath hyperthermia (41 degrees C, 45 min) could enhance binding of 111In-labeled anti-p97a monoclonal antibody (MAb) to human melanoma tumors transplanted subcutaneously into nude mice. Sixty animals were given injections of 1-2 X 10(7) Brown C5513 melanoma cells. At 1-2 weeks postinjection, two-thirds of the mice were treated (one-third served as controls). Within 3 hours after treatment, each animal was given iv 2 muCi 111In-anti-p97a MAb. At 24 and 48 hours thereafter, whole-body scans were done with the use of a MaxiCamera 300 A/M unit, and the ratio of activity at the tumor and liver was determined. Some animals were kept for 7 days posttreatment, whereas others were taken after the 48-hour scan for determination of biodistribution of the radiolabeled complex. Enhancement of MAb binding was demonstrated by either modality, although enhancement was more consistent with radiation. The therapeutic efficacy of MAb may be enhanced with increased binding of radioactive MAb complexes through single dose radiation or hyperthermia.