ASCO Genitourinary Cancers Symposium (Xofigo - Radium-223 retreatment)

[pjoshea13]

Darryl already reported this one, but the abstract is below [1].

Note that the half-life of radium-223 is only 11.4 days.

"The recommended regimen is six treatments of 55 kBq/kg (1.3 uCi per kg), repeated at 4-week intervals." [2]

"Re-treating with Ra-223 was well tolerated in this select pt population, led to minimal hematologic toxicity, and provided continued disease control in bone at 2-year follow-up." [1]

-Patrick

[1] 178 Poster Session (Board #H18), Thu, 11:30 AM-1:00 PM and

5:15 PM-6:15 PM

Radium-223 retreatment in an international, open-label, phase 1/2 study in patients with castration-resistant prostate cancer and bone metastases: 2-year follow-up.

A. Oliver Sartor, Daniel Heinrich, Neil Mariados, Mar ́ıa Jose ́ Me ́ndez-Vidal, Daniel Keizman, Camilla Thellenberg Karlsson, Avivit Peer, Giuseppe Procopio, Stephen Jay Frank, Kalevi Pulkkanen, Eli Rosenbaum, Stefano Severi, Jose Manuel Trigo Perez, Lucia Trandafir, Volker Jean Wagner, Rui Li, Luke T. Nordquist; Tulane University Cancer Center, New Orleans, LA; Akershus University Hospital, Lorenskog, Norway; Associated Medical Professionals of New York, PLLC, Syracuse, NY; Maimonides Institute of Biomedical Research, Reina Sofia Hospital, University of Cordoba, Cordoba, Spain; Meir Medical Center, Kfar-Saba, Israel; Cancer Center Norrlands University, Umea ̊, Sweden; Rambam Health Care Campus, Haifa, Israel; Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Hadassah Hebrew University Medical Center, Jerusalem, Israel; Kuopio University Hospital, Kuopio, Finland; Rabin Medical Center, Davidoff Center, Petah Tikva, Israel; Romagnolo Scientific Institute for the Study and Care of Cancer - IRST IRCCS, Meldola, Italy; Hospital Universitario Virgen de la Victoria, Ma ́laga, Spain; Bayer AG, Basel, Switzerland; Bayer HealthCare Pharmaceuticals Inc., Whippany, NJ; GU Research Network, LLC, Omaha, NE

Background: Radium-223 (Ra-223) treatment (tx) is indicated for patients (pts) with castration- resistant prostate cancer (CRPC) and symptomatic bone metastases (mets) (6 3 55 kBq/kg IV injections [inj]; 1 inj q4wk). Early results of an international, open-label, phase 1/2 study (NCT01934790) showed that re-treating pts with Ra-223 was well tolerated with favorable effects on disease progression. Here we report safety and efficacy findings from a 2-year follow-up.

Methods: Pts with CRPC and bone mets who completed 6 initial Ra-223 inj with no disease progression in bone and later progressed were eligible for Ra-223 re-tx (6 additional Ra-223 inj), provided that hematologic parameters were adequate. No concomitant cytotoxic agents were allowed; other concomitant agents (eg, abiraterone, enzalutamide) were allowed at investigator discretion. The primary objective was safety. Exploratory objectives were time to radiographic bone progression, radiographic progression- free survival (rPFS), overall survival (OS), time to first symptomatic skeletal event (SSE), and SSE-free survival, all calculated from re-tx start. Pts will be followed for safety up to 7 years after last Ra-223 dose; an active 2-year follow-up evaluated exploratory objectives. Safety results from the active follow-up period and updated efficacy are reported.

Results: 44 pts were re-treated with Ra-223; 29 (66%) completed all 6 inj (median number inj = 6). 34 (77%) of 44 pts entered active follow- up, during which no new safety concerns were noted. One new primary malignancy was reported (basal cell carcinoma). There were no serious drug-related adverse events. 19 (43%) of 44 pts had an rPFS event (radiographic progression or death); median rPFS was 9.9 months. Only 5 (11%) of 44 pts had radiographic bone progression; median time to radiographic bone progres- sion was not reached. Median OS was 24.4 months. Median time to first SSE and SSE-free survival were 16.7 and 12.8 months, respectively.

Conclusions: Re-treating with Ra-223 was well tolerated in this select pt population, led to minimal hematologic toxicity, and provided continued disease control in bone at 2-year follow-up. Clinical trial information: NCT01934790.

[2] en.wikipedia.org/wiki/Radiu...