Weill Cornell researchers recently published findings from a Phase II study of the lutetium-177-labeled monoclonal antibody J591 (called Lu-J591).
J591 is a man-made monoclonal antibody that is able to recognize a protein antigen (PSMA) expressed on virtually all prostate cancer cells, and more so in men with treatment-resistant metastatic disease. When a tiny tag of radioactive material is attached to the J591 antibody, that specifically targets prostate cancer cells, and delivered systemically this is known as “radioimmunotherapy.” Dr. Scott Tagawa and colleagues at Weill Cornell have been conducting clinical trials of the precision radioimmunotherapeutic J591 to determine its ability to eradicate prostate cancer cells.
In the recently published study, 47 prostate cancer patients with PSA progression after hormonal therapies with or without chemotherapy were treated with Lu-J591. 10.6 percent experienced more than 50% PSA decline, and 36.2% experienced more than 30% decline. Among those treated at the maximum tolerated dose, 46.9% had more than 30% PSA decline. Furthermore, 75% of patients with radiographically measurable disease had some measure of disease control; 67% of those assessed for circulating tumor cells had more than 50% decline in tumor cell counts 4 to 6 weeks after treatment.
The researchers concluded that a single dose of Lu-J591 was well tolerated and they found a measurable response rate. The authors conclude that Lu-J591 is a promising new therapeutic strategy to explore.