First Report of NRG Oncology RTOG 0622 : A Phase II Trial of Samarium-153 Followed by Salvage Prostatic Fossa Irradiation in High-Risk, Clinically Non-Metastatic Prostate Cancer after Radical Prostatectomy
Mené sur 60 patients ayant subi une prostatectomie radicale pour un cancer de la prostate à haut risque de récidive de stade T2-T4, N0-1, M0 (durée médiane de suivi : 4 ans), cet essai de phase II évalue l'intérêt, du point de vue du taux de réponse du PSA, de l'absence de progression de la maladie et du taux d'échec biochimique, et la toxicité d'un traitement comportant l'administration de samarium-153 puis une radiothérapie de sauvetage ciblant la zone de résection
Purpose : There is limited information regarding the utility of Samarium-153 lexidronam (Quadramet) in the setting of men with prostate cancer status post radical prostatectomy (RP), who develop biochemical failure with no clinical evidence of osseous metastases. Methods and Materials : Trial XXXX is a single-arm Phase II trial that enrolled men with pT2-T4, N0-1, M0 prostate cancer status post RP, who meet at least one of these biochemical failure criteria: (1) PSA >1.0ng/ml; (2) PSA >0.2ng/ml if Gleason score of 9-10; or (3) PSA >0.2ng/ml if N1. Patients received Samarium-153 (2.0mCi/kg IV x 1) followed by salvage external beam radiation therapy (EBRT) to the prostatic fossa (64.8-70.2Gy in 1.8Gy daily fractions). No ADT was allowed. The primary objective was PSA response within 12 weeks of receiving Samarium-153. The secondary objectives were to (1) assess the completion rate for the regimen of Samarium-153 and EBRT, (2) evaluate the hematological toxicity and other adverse events (AE) at 12 and 24 weeks, and (3) freedom from progression (FFP) rate at 2 years. Results : A total of 60 enrolled eligible patients were included in this analysis. Median follow up was 3.97 years. PSA response was achieved in 7/52 (13.5%) evaluable patients compared to the 25% hypothesized. The 2-year FFP was 25.5% (95% CI: 14.4-36.7%), and biochemical failure rate was 64.4% (95% CI: 50.5-75.2%). Samarium-153 was well tolerated, with 16/60 Grade 3-4 hematologic AEs and no Grade 5 hematologic AEs. RT was also well tolerated, with no Grade 3-5 acute RT-related AEs, and 1 Grade 3-4 and no Grade 5 late RT-related AEs. Conclusion : Trial XXXX did not meet its primary endpoint of PSA response, although the regimen of Samarium-153 and salvage EBRT was well tolerated. Although the toxicity profile supports study of Samarium-153 in high-risk disease, it may not be beneficial in men receiving EBRT.
http://www.redjournal.org/article/S0360-3016(17)34143-3/fulltext 2017