- 11 patients did not complete 3 cycles
- 5 discontinued due to non-response
- 4 discontinued due to xerostomia (dry mouth)
- 2 did not survive 8 weeks.
- 87% had some PSA decline
- 63% had a PSA decline greater than 50%
- Tumor control lasted 9.0 months (median)
- 5 patients had a response lasting more than 2 years
- Previous therapies with abiraterone lasted 10.0 months, docetaxel lasted for 6.5 months, enzalutamide for 6.5 months, and cabazitaxel for 6.0 months
These outcomes are impressive for a therapy given when all other therapies have failed. It is unclear whether it is better than Xofigo, the only approved radiopharmaceutical for metastatic castration-resistant prostate cancer. Xofigo only attacks cancer in bones, whereas Ac-225-PSMA attacks prostate cancer anywhere in the body.
Sathekge et al. reported the outcomes on 73 mostly chemotherapy-naive and abiraterone/enzalutamide-naive metastatic castration-resistant patients treated with Ac-225-PSMA-617 in South Africa. Most patients had 3 treatment cycles (every 2 months). Subsequent doses were lower to prevent side effects. PSA and metastatic activity was tracked using Ga-68-PSMA-617 PET scans.
- 83% of patients responded to treatment
- in 70% of patients, PSA declined by over 50%
- PSA declines of over 50% predicted longer progression-free survival and overall survival
- In 29% of patients, all lesions disappeared
- During follow-up, 23 patients (32%) had disease progression and 13 (18%) died of prostate cancer
- Progression-free survival was 15 months (median)
- Overall survival was 18 months
- Xerostomia (dry mouth) occurred in all 85% of patients, but it was not severe enough to stop treatment
- Anemia occurred in 27 patients (37%); none grade 4
- Grade 3 or 4 renal toxicity occurred in 5 patients with pre-existing renal impairment