Real-world treatment patterns with lutetium-177-PSMA-617 (177-Lu-PSMA) in patients with metastatic castrate-resistant prostate cancer (mCRPC).

e17064 Background: The VISION study demonstrated improved outcomes with up to 6 doses of 177 -Lu-PSMA plus standard-of-care (SOC) therapy versus SOC alone in pre-treated mCRPC patients, which led to its regulatory approval on 03/23/22. This is our real-world experience with 177 -Lu-PSMA at the University of California, Irvine and Hoag Hospital. Methods: This is a retrospective analysis of 22 patients with mCRPC treated with 177 -Lu-PSMA at the University of California, Irvine and Hoag Hospital since 03/23/2022. Baseline demographic, pathologic, and genomic characteristics of all patients who received 177 -Lu-PSMA (along with their outcomes) were analyzed. Results: Selected baseline characteristics of the study population are included in the table, which contrast treatment responders and non-responders. At the time of this analysis, 22.7% (5/22) of patients completed all 6 planned cycles of 177 -Lu-PSMA, 40.9% (9/22) discontinued early due to disease progression, 18.2% (4/22) are still receiving therapy, 9.1% (2/22) stopped treatment due to toxicity, and 9.1% (2/22) discontinued for other reasons. PSA reduction by at least 50% (PSA50) was achieved in 59.1% (13/22) of patients, 27.3% (6/22) achieved < PSA50, and 3/22 (13.6%) had no PSA response at all. In PSA responders, the median time to PSA nadir was 11.7 weeks range: 2.3 - 38.0, while the median time to second PSA rise above nadir was 6.0 weeks range, 4.0 – 22.3. Treatment related toxicities occurred in 54.5% (12/22) of patients, including 22.7% with dry mouth, 22.7% with fatigue, and 13.6% with nausea. Conclusions: This dataset highlightsreal-world treatment patterns with 177 -Lu-PSMA, which is an active and well-tolerated therapy. Despite initial response, some patients appear to have quick PSA progression, which led to early treatment discontinuation. We set out to evaluate if there were any baseline characteristics predictive of response among our patients. Ultimately, our data did not show any factors predictive of response to therapy. Given its financial toxicity, further studies identifying which patients are most likely to respond to 177 -Lu-PSMA are indicated. Table: see text