Symptomatic Skeletal Events Research Articles

A phase II trial in progress: Pamiparib, an investigational PARP inhibitor, in patients with metastatic castration-resistant prostate cancer and a circulating tumor cell homologous recombination deficiency (HRD) phenotype or BRCA defects.

TPS328 Background: Men with metastatic castration-resistant prostate cancer (mCRPC) who have a BRCA1/2 mutation ( BRCA1/2mut) or mutations in other HRD genes have a poor prognosis. The EPIC liquid biopsy test is a novel assay that can identify circulating tumor cells (CTC) with HRD associated phenotypes. Preliminary studies have shown that these men may respond to treatment with a PARP inhibitor. Pamiparib is an investigational PARP1/2 inhibitor that has shown brain penetration and potent PARP–DNA complex trapping in nonclinical studies. In early phase clinical studies (NCT02361723; NCT03333915), pamiparib was generally well tolerated and showed preliminary antitumor activity; 60 mg orally twice daily (BID) was established as the recommended investigational dose. Methods: This open-label, global, phase 2 study (NCT03712930) will evaluate antitumor activity and safety of pamiparib in mCRPC pts with CTC-HRD, assessed by the EPIC CTC-HRD assay, or deleterious germline/somatic BRCA1/2mut status. Patients must have progressed on/after ≥1 androgen receptor-targeted therapy, have received ≥1 taxane-based therapy, and have prostate-specific antigen (PSA) progression per PCWG3 criteria. Four cohorts of patients will receive pamiparib 60 mg BID in 28-day cycles. Cohort 1 will include ~50 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with measurable metastatic disease; Cohort 2 will include ~30 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with bone-only disease; Cohorts 3 & 4 will include ~20 pts with CTC-HRD-/unknown + BRCA1/2mut mCRPC with measurable metastatic disease (Cohort 3), or bone-only disease (Cohort 4). Disease status will be assessed every 8 wks for 24 wks, then every 12 wks; PSA levels will be tested every 4 wks. Co-primary endpoints are radiographic ORR assessed by IRC (pts with measurable disease) and confirmed PSA response rate per PCWG3 criteria (pts +/- measurable disease). Secondary endpoints include ORR, time to PSA response/progression, duration of PSA response, time to symptomatic skeletal event, radiographic progression-free survival, overall survival, and safety. Clinical trial information: NCT03712930.

Abstract P1-18-01: Incidence of hypocalcemia in patients with metastatic breast cancer under treatment with denosumab: A non-inferiority phase III trial assessing prevention of symptomatic skeletal events (SSE) with denosumab administered every 4 weeks versus every 12 weeks: SAKK 96/12 (REDUSE)

Abstract Background Monthly Denosumab (DN) has shown superiority over zoledronic acid (ZA) in delaying skeletal related events. Randomized trials have shown that ZA given every 12 weeks (q12w) is non-inferior to ZA given every 4 weeks (q4w). The primary endpoint of the REDUSE-trial is non-inferiority for SSE for DN q12w versus q4w. Here we present early data for hypocalcemia (HC), a secondary endpoint. Methods Patients with bone metastasis from breast cancer (BC) not pretreated with DN or Bisphosphonates were randomized 1:1 to receive DN q4w (Arm A) versus q12w (Arm B) after a 3-month induction phase with q4w therapy for both arms. All patients received vitamin D 400 U (VitD) and calcium (Ca) 500 mg daily. Measurement of albumin-corrected serum-Ca was mandatory before each DN injection (HC defined as <2.0 mmol/l like in CTCAE V4.0). This safety interim analysis was performed after 3.5 years of accrual. Patients who received at least 1 dose of DN were considered evaluable. Results 351 BC-patients are currently included (177 in Arm A, 174 in Arm B). HC was the most common side effect with a rate of 20% in the first 16 weeks (during the induction phase with DN q4w for both Arms) and 19% afterwards (combined for Arms A and B). After week 16 HC-prevalence differed between the two arms: while HC was present in 25% in Arm A (q4w), the rate was only 12% in Arm B (q12w). Grade 3 HC (i.e. corrected Ca 1.5 - 1.74 mmol/l or hospitalisation indicated) was rare (0.3%), no grade 4 HC occurred. After 1 year of treatment, the rate of HC compared to the induction phase had decreased in Arm B but not in Arm A (A: 25%, B: 12%). Since HC improved in more patients in Arm B than in Arm A whereas it worsened in more patients in Arm A than in Arm B, a remarkable difference for HC resulted between the two arms. Rates of hypocalcemia and change of severity after week 16* Arm A (N = 177)Arm B (N = 174)Rates of hypocalcemian (%)n (%)Patients with hypocalcemia at any time49 (28%)46 (26%)Patients with hypocalcemia after week 16*44 (25%)21 (12%) Change in hypocalcemia grade after week 16*for the 49 patients with hypocalcemiafor the 46 patients with hypocalcemiaWorsening25 (51%)8 (17%)Stable10 (20%)9 (20%)Improving14 (29%)29 (63%) *week 16: i.e. the time where the schedules of DN begin to differ between Arm A and Arm BArm A: DN q4w for weeks 1 - 12 and likewise thereafter / Arm B: DN q4w for weeks 1 - 12 and q12w thereafter Conclusions In our trial up to 20% of all BC patients treated with DN experienced HC in the q4w induction phase despite mandatory supplementation of VitD and Ca. This rate is considerably higher than the numbers reported in the registration trials of DN (where it was 5.5% for BC). After the induction phase, HC is markedly reduced in the q12w arm compared to q4w. This suggests that DN given q12w has a more favorable long-term safety profile in terms of HC compared to DN q4w. Citation Format: Müller A, Templeton AJ, Hayoz S, Hawle H, Hasler-Strub U, Schwitter M, Pestalozzi BC, Pagani O, Bützberger P, Wehrhahn T, Rauch D, Inauen R, Betticher D, Zaman K, Bodmer A, Popescu RA, Rothschild S, Schardt J, Borner M, Fuhrer A, Schär C, Gillessen S, von Moos R, For the Swiss Group for Clinical Cancer Research (SAKK). Incidence of hypocalcemia in patients with metastatic breast cancer under treatment with denosumab: A non-inferiority phase III trial assessing prevention of symptomatic skeletal events (SSE) with denosumab administered every 4 weeks versus every 12 weeks: SAKK 96/12 (REDUSE) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-18-01.

Optimizing antiresorptive treatment in patients with bone metastases: time to initiation, switching strategies, and treatment duration

PurposeThe aim of this study was to investigate the optimal use of antiresorptive therapy in patients with metastatic cancer in terms of time to treatment initiation, switching strategy in case of skeletal-related event (SRE) or skeletal disease progression, and treatment efficacy beyond 2 years.MethodsWe conducted a single-center retrospective cohort study including consecutive cancer patients with bone metastases that have received antiresorptive treatment between 2009 and 2015. The outcomes of interest were the time to first and subsequent symptomatic skeletal event (SSE), the skeletal morbidity rate, and the incidence of antiresorptive therapy-specific adverse events depending on the research question.ResultsIn total, 255 patients included in our study cohort. The time to treatment initiation (direct (n = 143 patients) vs. delayed (n = 87 patients) defined as > 3 months after diagnosis of bone metastases) was not found to influence the time to SSE in (hazard ratio (HR) 0.93; 95% confidence interval (CI) 0.65–1.34) with comparable toxicity. Switching strategy after first SRE or due to skeletal disease progression from bisphosphonates to denosumab was independently associated with longer time to SRE (HR 0.47, 95% CI 0.25–0.88, p value = 0.019) compared with continuation with the same bisphosphonate. Using the landmark approach at 24 months and including 121 patients that survived for more than 2 years, we found that treatment continuation beyond 2 years was associated with longer time to first SSE after 2 years (HR 0.41; 95% CI 0.19–0.93).ConclusionsOur hypothesis-generating results support a more individualized approach on antiresorptive treatment including the lack of detrimental effect when the treatment is delayed, the potential benefit of switching strategy after skeletal disease progression or SSE, and the benefit of continuing antiresorptive treatment beyond 2 years.

Radium-223 in asymptomatic patients with castration-resistant prostate cancer and bone metastases treated in an international early access program

BackgroundRadium-223, a targeted alpha therapy, is used to treat symptomatic patients with castration-resistant prostate cancer (CRPC) and bone metastases. Data for radium-223 in asymptomatic CRPC patients with bone metastases are lacking.MethodsThis was a prospective, single-arm phase 3b study. Patients with metastatic CRPC (malignant lymphadenopathy not exceeding 6 cm was allowed, visceral disease was excluded) received radium-223, 55 kBq/kg intravenously, every 4 weeks for up to 6 cycles. Co-primary endpoints were safety and overall survival. Post hoc analyses were performed according to baseline asymptomatic or symptomatic disease status. Asymptomatic status was defined as no pain and no opioid use at baseline.ResultsSeven hundred eight patients received ≥1 radium-223 injection: 548 (77%) were symptomatic to various degrees, and 135 (19%) were asymptomatic. Asymptomatic patients had more favorable baseline disease characteristics than symptomatic. A lower proportion of asymptomatic versus symptomatic patients had received prior abiraterone (25% vs 35%) and prior docetaxel (52% vs 62%). A higher proportion of asymptomatic (71%) versus symptomatic (55%) patients completed radium-223 treatment. Overall survival (hazard ratio [HR] 0.486), time to disease progression (HR 0.722) and time to first symptomatic skeletal event (HR 0.328) were better in asymptomatic than symptomatic patients. Alkaline phosphatase (ALP) response rates were similar (46% vs 47%), and ALP normalization (44% vs 25%) and prostate-specific antigen response rates (21% vs 13%) were higher in asymptomatic than symptomatic patients. A lower proportion of asymptomatic patients reported treatment-emergent adverse events (TEAEs, 61% vs 79%), grade 3–4 TEAEs (29% vs 40%) and drug-related TEAEs (28% vs 44%). There were two treatment-related deaths, both in patients with baseline symptomatic disease.ConclusionsUsing radium-223 earlier in the disease course, when patients are asymptomatic or minimally symptomatic, may enable patients to complete treatment and optimize treatment outcome compared to symptomatic patients, and therefore may allow sequencing with other life-prolonging therapies.Trial registrationThe study was registered with ClinicalTrials.gov, number NCT01618370 on June 13, 2012 and the European Union Clinical Trials Register, EudraCT number 2012–000075-16 on April 4, 2012.

Mechanistic Modeling of Radium-223 Treatment of Bone Metastases

Despite the effectiveness of 223RaCl2 for treating patients with symptomatic bone metastatic disease, its mechanisms of action are still unclear. Even established dosimetric approaches differ considerably in their conclusions. In silico tumor models bring a new perspective to this situation because they can quantitatively simulate the interaction of α-particles with the target(s). Here, we investigated 3 different mathematical models of tumor growth that consider the radiation effect of radium-223 (223Ra) treatments and compared the results with clinical data. The well-established Gompertz growth model was applied to simulate metastatic tumor burden. On the basis of published measurements of 223Ra uptake, we have incorporated the radiation effect of α-particles into the model and investigated 3 radium distribution scenarios-uniform exposure, exposure of only an outer layer, and exposure of a constant volume of the tumor. For each scenario, the times for various tumor stages to progress to the first symptomatic skeletal event were calculated. Uniform and outer-layer exposure scenarios showed very poor agreement with the Kaplan-Meier patient curves from clinical data. However, the constant-volume effect predicted outcomes very similar to the observed clinical results, suggesting, depending on the dose rate, that relatively small fractions of the cell population see damage from 223Ra. The commonly used assumption of uniform 223Ra distribution does not accurately reflect clinical responses. The suggestion that only a subpopulation of the tumor might be affected by 223Ra shows a pressing need to further study the tumor and drug kinetics to schedule more effective treatments in the future.

Denosumab versus zoledronic acid for preventing symptomatic skeletal events in Asian postmenopausal women with oestrogen-receptor-positive advanced breast cancer: an outcome analyses with a mean follow-up of 3\u2009years

BackgroundThe purpose of this study was to evaluate the efficacy of denosumab or zoledronic acid (ZA) using symptomatic skeletal events (SSEs) as the primary endpoint in Asian postmenopausal women with oestrogen-receptor-positive advanced breast cancer.MethodsAsian postmenopausal women with oestrogen-receptor-positive advanced breast cancer receiving subcutaneous denosumab 120 mg Q4W, or intravenous ZA 4 mg Q4W until the primary analysis cut-off date were retrospectively analysed in the Hong Kong Practice-Based Cancer Research Center(HKCRC) from March 2011 to March 2013. The time to first on-study SSE that was assessed either clinically or through routine radiographic scans was the primary endpoint.Results242 patients received denosumab or ZA treatment (n = 120, mean age of 64.9 years (SD 3.01) and n = 122, 65.4 years (3.44), respectively). The median times to first on-study SSE were 14.7 months (12.9–45.6) and 11.7 months (9.9–45.6) for denosumab and ZA, respectively (hazard ratio, HR 0.44, 95% CI 0.71–2.95; p = 0·0002). Compared with the ZA group, denosumab-treated patients had a significantly delayed time to first SSE (HR 0.65 [95% CI 0.29–1.45], p < 0.0001). An increased incidence of SSE was found in the 16-month follow-up with rates of 2.1 and 10.7% for denosumab and ZA, respectively (P = 0.033). The difference persisted with time with rates of 8.3 and 17.2% at the final follow-up, respectively (P < 0.05).ConclusionIn postmenopausal women aged ≥60 years with oestrogen-receptor-positive advanced breast cancer, denosumab significantly reduced the risk of developing SSEs compared with ZA. The findings of this pilot trial justify a larger study to determine whether the result is more generally applicable to a broader population.

Radium-223 in patients with metastatic castration-resistant prostate cancer: Efficacy and safety in clinical practice.

Radium-223 has improved overall survival (OS) and reduced symptomatic skeletal events (SSE) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases (ALSYMPCA trial). Our aim was to assess clinical and biochemical factors related to survival, safety and survival outcomes of Radium-223 in a clinical practice setting. We retrospectively analysed 32 mCRPC patients treated with Radium-223, assessing bone scan, pain reduction, alkaline phosphatase (ALP) and prostate-specific antigen (PSA) response (≥30% reduction). At scintigraphic assessment, 41% had partial response with a disease control rate of 91%; 56% had ALP response and 25% had PSA response; 41% had pain reduction with pain control of 72%. Scintigraphic response and stability were correlated with longer median progression-free survival (mPFS) (13 and 12 vs. 6 months; P=0.002) and mOS (16 and 12 vs. 6 months; P=0.003). ALP response was associated with longer mPFS (13 vs. 12 months; P=0.2) and mOS (16 vs. 12 months; P=0.2). PSA response was associated with longer mPFS (13 vs. 12 months; P=0.02), whereas mOS could not be computed. Pain response and stability were associated with survival benefit according to mPFS (13 and 12 vs. 9 months) and mOS (both 16 vs. 12 months) without statistical significance. Baseline ALP <220 UI/l, Eastern Cooperative Oncology Group (ECOG) performance status 0 and absence of previous chemotherapy correlated with statistically significantly longer survival outcomes. Skeletal-related events (SRE) occurred in three patients and median time to first SRE was 9.5 months, mPFS was 12 months and mOS 14 months. G3-G4 toxicities developed in 16% of patients. Our results are in line with those reported in the pivotal trial and in other retrospective studies. In conclusion, Radium-223 was associated with high scintigraphic, biochemical and pain response rates and was tolerated well by most patients. Response to Radium-223 and better baseline factors correlated to longer survival in clinical practice experience as in the clinical trial setting.

828P - Symptomatic skeletal event (SSE) dynamics in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 (Ra-223): An interim review of a prospective, non-interventional study (PARABO)

828P - Symptomatic skeletal event (SSE) dynamics in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 (Ra-223): An interim review of a prospective, non-interventional study (PARABO)

1703P - Incidence of hypocalcemia in a non-inferiority phase III trial assessing prevention of symptomatic skeletal events (SSE) with denosumab (DN) administered every 4 weeks (q4w) versus every 12 weeks (q12w): SAKK 96/12 (REDUSE)

1703P - Incidence of hypocalcemia in a non-inferiority phase III trial assessing prevention of symptomatic skeletal events (SSE) with denosumab (DN) administered every 4 weeks (q4w) versus every 12 weeks (q12w): SAKK 96/12 (REDUSE)

824P - Radium-223 (Ra-223) therapy after abiraterone (Abi): Analysis of symptomatic skeletal events (SSEs) in an international early access program (iEAP) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

824P - Radium-223 (Ra-223) therapy after abiraterone (Abi): Analysis of symptomatic skeletal events (SSEs) in an international early access program (iEAP) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

815P - Symptomatic skeletal related events (SSE) and SSE-free-survival in real world castration-resistant prostate cancer (CRPC) patients: Results from CAPRI

815P - Symptomatic skeletal related events (SSE) and SSE-free-survival in real world castration-resistant prostate cancer (CRPC) patients: Results from CAPRI

The burden of symptomatic skeletal events in castrate-resistant prostate cancer patients with bone metastases at three Canadian uro-oncology centres.

Metastatic bone disease in castrate-resistant prostate cancer risks significant morbidity, including symptomatic skeletal events. We estimated the healthcare resource costs of managing skeletal events. A retrospective chart review was conducted for patients who died from or were treated palliatively for metastatic castrate-resistant prostate cancer from 2006-2013 at Centre Hospitalier de l'Université de Montréal (Montreal), Princess Margaret Cancer Centre (Toronto), or Vancouver General Hospital (Vancouver). Of 393 patients, 275 (70%) experienced 833 events (85 per 100 patient-years), with a median (95% confidence interval) time (months) to first event of 17.6 (15.3, 21.7). The mean metastatic bone disease-related healthcare resource use cost (2014 Canadian dollars) estimate for patients without symptomatic skeletal events was $9550 and between $22 101 (observed) and $34 615 (adjusted) for patients with at least one event. Fewer patients in Montreal (55%) experienced events compared to Toronto (79%) or Vancouver (76%). Median time (months) to first event was longer in Montreal (25.0 [18.5, 32.6]) than in Toronto (14.6 [9.7, 16.8] or Vancouver (17.3 [14.8, 24.0]). More patients received bone-targeted therapy in Montreal (64%) and Toronto (60%) than in Vancouver (24%). Bone-targeted therapy was mostly administered every 3-4 weeks in Montréal and every 3-4 months in Toronto. Metastatic bone disease-related healthcare resource use costs for Canadian castrate-resistant prostate cancer patients are high. Symptomatic skeletal events occurred frequently, with the incremental cost of one or more events estimated between $12 641 and $25 120. Symptomatic skeletal event incidence and bone-targeted therapy use varied considerably between three Canadian uro-oncology centres. An important limitation is that only patients who died from prostate cancer were included, potentially overestimating costs.

Single vs multiple fraction palliative radiotherapy for uncomplicated painful bone metastases treated at University of Malaya Medical Centre: A single institutional Malaysian experience.

IntroductionThis study was conducted to compare pain response between single and multiple fraction palliative radiotherapy and to describe prognostic factors affecting treatment response in University of Malaya Medical Centre (UMMC).MethodsThe case records of 162 patients with uncomplicated painful bone metastases treated with palliative radiotherapy from 2006 to 2014 were analyzed. Treatment outcomes were pain score response, analgesic score response, response according to International Consensus Endpoints (complete response and overall response) at 4, 12, and 24 weeks, retreatment rate, symptomatic skeletal events (SSEs), and prognostic factors.ResultsAt 24 weeks, pain score response for single and multiple fraction group was 82.3% and 88.5%, analgesic score response was 54.8% and 61.5%, and overall response according to International Consensus Endpoint was 61.3% and 67.7%, respectively. There was no statistically significant difference in treatment response between the 2 treatment groups for all endpoints. ECOG (<2 vs ≥2: aOR 3.405, 95% CI 1.708‐6.790, P = .001) and primary breast and prostate (breast vs others: aOR 5.231, 95% CI 1.973‐13.869, P = .001; prostate vs others: aOR 5.522, 95% CI 1.493‐20.420, P = .01) were significant variables on multivariate analysis.ConclusionSingle fraction radiotherapy is as effective as multiple fraction radiotherapy for the palliation of uncomplicated bone metastases.

A randomized phase 2 study investigating 3 dosing regimens of radium-223 dichloride (Ra-223) in bone metastatic castration-resistant prostate cancer (mCRPC).

5008Background: Ra-223, standard dose (SD) 55 kBq/kg q4w for 6 cycles improved overall survival (OS) and delayed time to symptomatic skeletal events (SSEs) in patients (pts) with mCRPC and bone met...

Clinical response to radium-223 dichloride in men with metastatic castrate-resistant prostate cancer

Purpose/ObjectiveRadium-223 prolongs survival and decreases symptomatic skeletal events in men with metastatic castrate-resistant prostate cancer and is indicated in patients with painful bone metastases. However, pain responses are rarely reported and often asked about by patients. Further, patients and their physicians are concerned about a lack of pain response portending a poor treatment response and may be inclined to change systemic therapies before completing 6 cycles. We evaluated the likelihood and time course of pain response, potential predictors of response, and its prognostic value in patients receiving radium-223. Materials and MethodsWe reviewed the charts of patients who received radium-223 in our department. All patients were planned for 6 cycles with a prescribed dose of 50–55 kBq/kg at each administration. Pain scores, subjective response to pain, analgesic use, treatment toxicities, and laboratory values were recorded at each visit. Symptomatic skeletal events and survival were also recorded. Results48 patients received at least one cycle of radium-223 and 27 (56%) received all 6 planned cycles. Median survival from first treatment was 16.0 months (95% CI 8.9 to 19.2 months). 33% experienced at least one symptomatic skeletal event during or after treatment. 62.5% of men reported a decrease in pain from pre-treatment baseline. Of men with improved pain, 96% experienced an improvement before the third cycle. Pain relief was not associated with a decrease in ALK-P or PSA or improved survival. ConclusionsApproximately two-thirds of patients who undergo treatment with radium-223 will experience an improvement in pain and, if it occurs, it will most likely occur within the first two cycles. Patients should be counseled about this timeline and, if pain improvement isn't achieved, palliative radiation and oral analgesic readjustment should be considered. Pain response is not associated with survival and should not be used to evaluate the effectiveness of treatment.

Adding abiraterone or docetaxel to long-term hormone therapy for prostate cancer: directly randomised data from the STAMPEDE multi-arm, multi-stage platform protocol

BackgroundAdding abiraterone acetate with prednisolone (AAP) or docetaxel with prednisolone (DocP) to standard-of-care (SOC) each improved survival in systemic therapy for advanced or metastatic prostate cancer: evaluation of drug efficacy: a multi-arm multi-stage platform randomised controlled protocol recruiting patients with high-risk locally advanced or metastatic PCa starting long-term androgen deprivation therapy (ADT). The protocol provides the only direct, randomised comparative data of SOC+AAP versus SOC+DocP. MethodRecruitment to SOC+DocP and SOC+AAP overlapped November 2011 to March 2013. SOC was long-term ADT or, for most non-metastatic cases, ADT for≥2years and RT to the primary tumour. Stratified randomisation allocated pts 2:1:2 to SOC; SOC+docetaxel 75mg/m2 3-weekly×6+prednisolone 10mg daily; or SOC+abiraterone acetate 1000mg+prednisolone 5mg daily. AAP duration depended on stage and intent to give radical RT. The primary outcome measure was death from any cause. Analyses used Cox proportional hazards and flexible parametric models, adjusted for stratification factors. This was not a formally powered comparison. A hazard ratio (HR) <1 favours SOC+AAP, and HR>1 favours SOC+DocP. ResultsA total of 566 consenting patients were contemporaneously randomised: 189 SOC+DocP and 377 SOC+AAP. The patients, balanced by allocated treatment were: 342 (60%) M1; 429 (76%) Gleason 8–10; 449 (79%) WHO performance status 0; median age 66years and median PSA 56ng/ml. With median follow-up 4years, 149 deaths were reported. For overall survival, HR=1.16 (95% CI 0.82–1.65); failure-free survival HR=0.51 (95% CI 0.39–0.67); progression-free survival HR=0.65 (95% CI 0.48–0.88); metastasis-free survival HR=0.77 (95% CI 0.57–1.03); prostate cancer-specific survival HR=1.02 (0.70–1.49); and symptomatic skeletal events HR=0.83 (95% CI 0.55–1.25). In the safety population, the proportion reporting≥1 grade 3, 4 or 5 adverse events ever was 36%, 13% and 1% SOC+DocP, and 40%, 7% and 1% SOC+AAP; prevalence 11% at 1 and 2 years on both arms. Relapse treatment patterns varied by arm. ConclusionsThis direct, randomised comparative analysis of two new treatment standards for hormone-naïve prostate cancer showed no evidence of a difference in overall or prostate cancer-specific survival, nor in other important outcomes such as symptomatic skeletal events. Worst toxicity grade over entire time on trial was similar but comprised different toxicities in line with the known properties of the drugs. Trial registrationClinicaltrials.gov: NCT00268476.

A meta-analysis on individual data of bone-targeting radio-isotopes in men with bone metastases from castration-resistant prostate cancer.

352 Background: Among bone-targeted radio-isotopes (RI), Radium-223 (an α-emitter) is the only one with clearly demonstrated overall survival (OS) benefit in men with castration-resistant prostate cancer (CRPC). The aim of this meta-analysis is to estimate the OS impact of RI in men with CRPC. Methods: An individual patient data meta-analysis was carried out from randomized trials with inclusion period 1993-2013. Eligible trials included more than 50 patients, mandated bone metastases from CRPC and randomly evaluated RI. Endpoints were OS (primary), symptomatic skeletal events (SSE) and toxicity. A fixed-effect model was used. The log-rank test stratified by trial was used to estimate individual and overall hazard ratios (HR). Subset analyses were performed by the type of radiation (α vs. β emission) and by trial comparison: RI + Chemotherapy (CT) vs. CT, RI+ External beam radiotherapy (EBRT) vs. EBRT, RI vs. EBRT. Results: From 9 identified trials, data from 6 trials comprising 2081 patients (min: 64, max: 921) were collected with 2 trials representing 80% of data. The data from 3 trials (n = 341) were not available. The overall effect on OS favoured RI with HR = 0.86 [0.77-0.95] but high heterogeneity between trials (p &lt; 0.001, I2= 79.6%). The overall effect of α- emitters on OS (HR = 0.70 [0.58; 0.83], 2 trials, n = 985) significantly differed from that of β-emitters (HR = 0.96 [0.84; 1.10], n = 4 trials, n = 1096) (interaction p = 0.0041). The overall effect on SSE favoured RI with HR = 0.81 [0.69-0.93] (4 trials, n = 1806) with marked between trial heterogeneity (p = 0.08, I² = 55.3%) and a significant difference (p = 0.02) by the type of RI (α-emitters: HR = 0.65 [0.52-0.82]-2 trials, β-emitters: HR = 0.93 [0.77-1.13]-2 trials). Conclusions: In men with metastatic CRPC a significant improvement of OS and SSE was obtained with bone targeted α-emitter radio isotopes, but not with β-emitter. However, some between trial heterogeneity of effects on OS need further investigations.

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.

178 Background: Radium-223 (Ra-223) treatment (tx) is indicated for patients (pts) with castration-resistant prostate cancer (CRPC) and symptomatic bone metastases (mets) (6 × 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 progression 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.

ARASENS: A phase 3 trial of darolutamide in combination with docetaxel for men with metastatic hormone-sensitive prostate cancer (mHSPC).

TPS383 Background: The addition of either docetaxel or abiraterone acetate plus prednisone to androgen deprivation therapy (ADT) improves overall survival (OS) compared with ADT alone in men with mHSPC. It is hypothesized that other androgen receptor (AR)-targeted therapies could be combined with docetaxel for mHSPC. Darolutamide (ODM-201) is an investigational oral AR antagonist with a unique chemical structure and negligible blood-brain barrier penetration that inhibits tumor growth by binding to AR and AR mutants (eg, W742L and F877L) with high affinity and specificity. In phase 1/2 ARADES and phase 1 ARAFOR trials, darolutamide demonstrated antitumor activity and was well tolerated in men with metastatic castration-resistant prostate cancer (mCRPC). ARASENS will evaluate the addition of darolutamide to standard ADT and docetaxel in men with mHSPC. Methods: This international, randomized, double-blind, placebo-controlled phase 3 trial (NCT02799602) is being conducted at &gt; 300 sites in 23 countries. ~1300 men with newly diagnosed mHSPC will be randomized 1:1 to darolutamide (600 mg orally twice daily) or matching placebo. All patients will receive standard ADT + docetaxel (6 cycles). Patients will be stratified by disease extent and alkaline phosphatase level. Key inclusion criteria: histologically or cytologically confirmed PC with documented metastases, started ADT ± first-generation antiandrogen therapy ≤12 weeks before randomization, and ECOG performance status 0-1. The primary end point is OS. Secondary end points include time to mCRPC, initiation of subsequent anticancer therapy, symptomatic skeletal event (SSE)-free survival, time to first SSE, first opioid use, pain progression, and worsening of physical symptoms. Safety will be assessed. ARASENS is actively enrolling at &gt; 280 sites across 23 countries. Clinical trial information: NCT02799602.

Intergroup study EORTC-1333-GUCG: A randomized multicenter phase III trial comparing enzalutamide vs. a combination of Ra223 and enzalutamide in asymptomatic or mildly symptomatic castration resistant prostate cancer (CRPC) patients metastatic to bone (PEACE III).

TPS390 Background: α-emitting radiopharmaceutical Ra-223 reduces the risk of death by 30% vs placebo in phase 3 ALSYMPCA (Parker et al. NEJM 2013). Ra-223’s favourable safety profile and lack of significant toxicity support combining it with other agents. The ALSYMPCA trial was developed to add Ra-223 on the contemporary standard of care that did not include last generation AR pathway inhibitors enzalutamide, one of the modern reference treatments for asymptomatic or moderately symptomatic metastatic CRPC (Gillessen et al. Eur Urol. 2017). In addition Ra-223 is registered in symptomatic prostate cancer (PCa), a very late stage of modern patient disease. There is thus a good rationale to combine Ra-223 to modern AR pathway inhibitors and to initiate the treatment in asymptomatic or moderately symptomatic patients. Methods: The EORTC 1333-GUCG study will run in 51 sites (21 activated) across 7 European countries, 4 sites in US and 12 sites in Canada. The study is an intergroup initiative between EORTC (Coordinating Group), UNICANCER; Cancer Trials Ireland (Ireland), ACCRU (The United States), and CUOG (Canada). A total of 560 patients will be randomized in a 1:1 ratio to receive enzalutamide 160 mg q.d. p.o. or enzalutamide at the same dose and Ra223 at 55 kBq/kg i.v. monthly for 6 months. Patients will be stratified by country, pain (BPI 0-1 vs BPI 2-3), prior docetaxel use (no vs yes) and use of bone targeting agents (no vs yes). The main inclusion criteria require asymptomatic or mildly symptomatic (defined as no opioids and BPI-SF question 3 &lt; 4), metastatic to bone with ≥ 2 bone metastases with or without additional lymph node metastases. Visceral metastases are not allowed. The primary endpoint is radiological progression-free survival (rPFS1), according to PCWG3. Secondary endpoints include: overall survival, PCa specific survival, 1st symptomatic skeletal event (SSE), time to initiation of next systemic anti-neoplastic therapy, time to pain progression, health-related quality of life (EQ-5D-5L and BPI). Clinical trial information: NCT02194842.