Treatment with radiolabeled J591 plus ketoconazole and hydrocortisone may delay time to metastasis in patients with high-risk, non-metastatic castration-resistant prostate cancer (nmCRPC), according to researchers.
The combination produced a biochemical response in high-risk nmCRPC patients in a phase 2 trial. In addition, there was a numeric, but not significant, improvement in metastasis-free survival (MFS) when J591 was radiolabeled with 177Lutetium (177Lu) rather than 111Indium (111In).
These results were presented at the 2023 ASCO Genitourinary Cancers Symposium by Scott T. Tagawa, MD, of Weill Cornell Medicine/New York-Presbyterian Hospital in New York, New York.
The phase 2 trial (ClinicalTrials.gov Identifier: NCT00859781) included 55 patients with high-risk nmCRPC. At baseline, the median age was 68 years (range, 52-88), the median prostate-specific antigen (PSA) level was 8.0 ng/mL (range, 1-78), and the median PSA doubling time was 3 months (range, 0.87-7.85). Most patients (75%) had undergone prostatectomy, 22% had primary radiation, and 22% had local salvage therapy.
Study treatment consisted of a minimum 4 week lead-in with ketoconazole at 400 mg 3 times a day and hydrocortisone at 20 mg in the morning and 10 mg in the evening. Patients also received a single infusion of J591, an anti-prostate-specific membrane antigen antibody, radiolabeled with 177Lu or 111In.
In the intent-to-treat population (n=46), the incidence of metastasis at 18 months was 50% with 177Lu-J591 and 76% with 111In-J591 (P =.066). The median MFS was 23.8 months and 20.8 months, respectively.
The median biochemical progression-free survival was 18.67 months with 177Lu-J591 and 8.87 months with 111In-J591. There was a confirmed greater than 50% PSA decline in 82% of patients treated with 177Lu-J591 and 71% of those treated with 111In-J591.
Grade 3 or higher hematologic adverse events (AEs) that were more common with 177Lu-J591 than with 111In-J591 included neutropenia (57% vs 11%) and thrombocytopenia (77% vs 11%). Grade 3 or higher non-hematologic AEs that were less common with 177Lu-J591 than with 111In-J591 included abdominal pain (0 vs 11%), ALT increase (3.3% vs 22%), and diarrhea (0 vs 22%).
Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Tagawa ST, Thomas C, Adra N, et al. Randomized, double-blinded phase II study of ketoconazole (keto), hydrocortisone (HC), and anti-PSMA antibody J591 labeled with 177Lu or 111In in patients (pts) with high-risk non-metastatic (met) castration-resistant prostate cancer (M0 CRPC). Presented at ASCO GU 2023. February 16-18, 2023. Abstract LBA21.
This article originally appeared on Cancer Therapy Advisor