Important First US Clinical Trial Reports Effectiveness of a New Treatment

Metastatic prostate cancer remains an incurable disease for which the mainstay of treatment for the past 80 years has been hormonal therapies that reduce the growth-stimulating effects of male hormones on prostate cancer cells. In the overwhelming majority of cases, hormonal therapy induces a remission that may range from a few years to even decades. In addition, the recent development of “add-on” hormonal agents, chemotherapies, immunotherapies, and radioactive isotopes have in some cases prolonged remissions and increased cancer-specific and overall survival.

In this issue of Quest (see “The Room Where it Happened” on page 1), we highlight the researchers whose work led to the development of an agent consisting of a humanized antibody directed against a tumor cell marker called PSMA attached to a radioactive isotope ¹⁷⁷lutetium that not only provides scans with unparalleled imaging of prostate cancer metastases but also serves as a therapeutic agent that can treat the cancer and prolong survival in patients whose tumor no longer responds to conventional therapy.

The clinical trial recently published in the New England Journal of Medicine and summarized briefly below was highlighted in a New York Times article by Roni Caryn Rabin on June 24, 2021.

In this trial (funded by a company) of 831 patients with metastatic prostate cancer no longer responding to hormonal therapy who had a PSMA-positive ⁶⁸gallium-PSMA PET scan, patients were randomized to receive ¹⁷⁷lutetium-PSMA-617 or standard care. At a median follow-up of nearly 21 months, the ¹⁷⁷Lu-PSMA-617-treated patients had an approximately 60% lower risk of cancer progression or death (8.7 vs. 3.4 months) and about a 38% longer overall survival (15.3 vs 11.3 months). The incidence of severe adverse events was higher with ¹⁷⁷Lu-PSMA-617 than without (52.7% vs. 38.0%), but quality of life was not adversely affected.

Sartor O, et al, New Engl J Med June 23, 2021