New treatment option offers disease control and extends the life of patients with advanced prostate cancer

Cancer researchers say they have established a new, life-extending treatment option for men with prostate cancer that has spread and become resistant to hormone therapy. The injected treatment combines a targeted compound with a radioactive isotope to irradiate and kill cancer cells.

Targeted radioligand therapy was tested in subjects with advanced prostate cancer in an international clinical trial sponsored by Endocyte, Inc., a Novartis company. All of the subjects had cancer that had spread to other organs and progressed after previous treatment with two types of drugs, androgen axis inhibitors and taxanes. The experimental treatment significantly increased survival, delayed progression, and was generally well tolerated by study participants, the researchers said.

This is an entirely new treatment option that will extend life and disease control in metastatic castration-resistant prostate cancer – the most aggressive and deadly form. “

Tom Beer, MD, a principal investigator and associate director of the Knight Cancer Institute at Oregon Health & Science University

The additional option is particularly important, Beer said, as the most effective treatments currently being developed for metastatic castration-resistant prostate cancer are now being used to treat early-stage diseases.

“Some of our best treatments are used sooner, so you have fewer options when you have metastatic castration-resistant disease,” he said.

Beer co-authored the results presentation at the American Society of Clinical Oncology’s annual meeting on Sunday. The OHSU Knight Cancer Institute was among the top sites for enrolling study participants.

The experimental therapy is called Lutetium-177-PSMA-617. It carries the radioactive isotope Lutetium-177 and targets the prostate-specific membrane antigen, or PSMA, a protein found on the surface of most prostate cancer cells. Once injected into the bloodstream, the drug binds to prostate cancer cells that carry PSMA, selectively delivering radiation to the cancer. The beta particle radiation emitted acts over short distances to limit the damage to the surrounding tissue.

More than 80 percent of advanced prostate cancers carry the PSMA protein, and patients with PSMA-bearing tumors can be identified with a PET scan.

More than 800 subjects at 84 locations took part in the randomized clinical phase 3 study. They were randomly given Lutetium-177-PSMA-617 in addition to the standard of care or received the standard of care alone. Those in the experimental therapy group received intravenous infusions of radioligand therapy every six weeks for up to six cycles.

Overall survival was significantly longer in the patients treated with the targeted radioligand: a median of 15.3 months versus 11.3 months. Survival without tumor progression was also significantly longer in the radioligand group: a median of 8.7 months versus 3.4 months.

The researchers said the effect of Lutetium-177-PSMA-617 treatment on overall survival was significant, especially as the disease progressed in all participating subjects despite treatment with modern androgen axis inhibitors and taxane chemotherapy. They said ongoing studies will answer the question of whether targeted radioligand therapy can provide therapeutic benefits earlier in the treatment sequence than was the case in this clinical study.

The incidence of Grade 3 or greater treatment-related adverse events was higher in the targeted radioligand group than in the standard treatment group. Fatigue, dry mouth, and nausea were the most commonly reported adverse reactions in the radioligand group.

“It’s pretty well tolerated,” said Beer. “I think there will be an asset in treating cancer without placing too much stress on patients.”

The OHSU Knight Cancer Institute is a national leader in prostate cancer treatment and research, expanding access to clinical trials and the latest treatments. With the VA Portland Health Care System, the Knight Cancer Institute has established a competence center for prostate cancer precision oncology.


Oregon Health & Science University

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