A randomised phase II trial of three dosing regimens of radium-223 in patients with bone metastatic castration-resistant prostate cancer.

BACKGROUND: Radium-223 prolongs overall survival and delays symptomatic skeletal events (SSEs) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. The approved radium-223 regimen is 55 kBq/kg every 4 weeks (q4w) for six cycles (standard dose). We investigated different radium-223 regimens in patients with mCRPC. PATIENTS AND METHODS: Patients were randomised 1 : 1 : 1 to radium-223 standard-dose, high-dose (88 kBq/kg q4w for six cycles) or extended-schedule arms (55 kBq/kg q4w for 12 cycles). The primary end point, SSE-free survival (SSE-FS), was compared in patients treated with a high- versus standard-dose regimen, or with a standard dose in an extended (>6 to 12 cycles) versus standard schedule (six cycles). RESULTS: A total of 391 patients were randomised; baseline characteristics were balanced between arms. On-treatment SSEs developed in 37/130 (28%), 42/130 (32%) and 48/131 (37%) patients in the standard-dose, high-dose and extended-schedule arms, respectively. There was no statistically significant difference in SSE-FS in the high- versus standard-dose arms [median 12.9 months versus 12.3 months; hazard ratio (HR) 1.06, 80% confidence interval (CI) 0.88-1.27, P = 0.70], and in the extended- versus standard-schedule arms (median 10.8 months versus 13.2 months; HR 1.26, 80% CI 0.94-1.69, P = 0.31). Overall survival in the three treatment arms was similar. As many as 370 (95%) patients received treatment (median of six cycles) in each arm. Grade ≥3 treatment-emergent adverse events (TEAEs) affected 34% of patients in the standard-dose, 48% in the high-dose and 53% in the extended-schedule arm, causing permanent discontinuation in 9%, 16% and 17% of patients, respectively. CONCLUSION: Radium-223 high-dose or extended-schedule regimens resulted in no change in SSE-FS or other efficacy end points and were associated with more grade ≥3 TEAEs. The extended-schedule regimen (beyond six doses) could not be implemented in a large proportion of patients due to disease progression. Therefore, the standard-dose schedule remains one of the standard therapies for patients with symptomatic mCRPC. TRIAL REGISTRATION: ClinicalTrials.govNCT02023697.

Apalutamide and overall survival in non-metastatic castration-resistant prostate cancer.

BACKGROUND: In the SPARTAN study, compared with placebo, apalutamide added to ongoing androgen deprivation therapy significantly prolonged metastasis-free survival (MFS) and time to symptomatic progression in patients with high-risk non-metastatic castration-resistant prostate cancer (nmCRPC). Overall survival (OS) results at the first interim analysis (IA1) were immature, with 104 of 427 (24%) events required for planned final OS analysis. Here, we report the results of a second pre-specified interim analysis (IA2). METHODS: One thousand two hundred and seven patients with nmCRPC were randomized 2 : 1 to apalutamide (240 mg daily) or placebo. The primary end point of the study was MFS. Subsequent therapy for metastatic CRPC was permitted. When the primary end point was met, the study was unblinded. Patients receiving placebo who had not yet developed metastases were offered open-label apalutamide. At IA2, pre-specified analysis of OS was undertaken, using a group-sequential testing procedure with O'Brien-Fleming-type alpha spending function. Safety and second progression-free survival (PFS2) were assessed. RESULTS: Median follow-up was 41 months. With 285 (67% of required) OS events, apalutamide was associated with an improved OS compared with placebo (HR 0.75; 95% CI 0.59-0.96; P = 0.0197), although the P-value did not cross the pre-specified O'Brien-Fleming boundary of 0.0121. Apalutamide improved PFS2 (HR 0.55; 95% CI 0.45-0.68). At IA2, 69% of placebo-treated and 40% of apalutamide-treated patients had received subsequent life-prolonging therapy for metastatic CRPC. No new safety signals were observed. CONCLUSION: In patients with nmCRPC, apalutamide was associated with a 25% reduction in risk of death compared with placebo. This OS benefit was observed despite crossover of placebo-treated patients and higher rates of subsequent life-prolonging therapy for the placebo group.

The evolution and understanding of skeletal complication endpoints in clinical trials of tumors with metastasis to the bone.

Bone metastases are a frequent complication of solid tumors, leading to significant skeletal sequelae that negatively impact quality of life and survival. Prevention and management of skeletal-related complications are critical treatment goals in oncology. Endpoints used in clinical trials to evaluate skeletal-related complications have evolved. In contrast to single measures of bone health, contemporary clinical trial endpoints reflect composite measures of skeletal-related complications, and increasingly also survival. In addition, key symptomatic components, which are more reflective of quality of life and the patient experience, are being incorporated. Given the evolution and resulting diversity of the endpoints being used in pivotal trials, it is becoming increasingly relevant to clarify the utility and the potential clinical impact of these measures not only within the context of trials but also in the real-world setting. Here, we describe the development and evolution of skeletal endpoints used in trials, and discuss their clinical relevance.

Efficacy and safety of enzalutamide in patients 75 years or older with chemotherapy-naive metastatic castration-resistant prostate cancer: results from PREVAIL.

BACKGROUND: Prostate cancer disproportionately affects older men. Because age affects treatment decisions, it is important to understand the efficacy and tolerability of therapies for advanced prostate cancer in elderly men. This analysis describes efficacy and safety outcomes in men aged ≥75 years who received enzalutamide, an androgen receptor inhibitor, in the phase III PREVAIL trial. PATIENTS AND METHODS: PREVAIL was a randomised, double-blind, multinational study of oral enzalutamide 160 mg/day (N = 872) versus placebo (N = 845) in chemotherapy-naive men with metastatic castration-resistant prostate cancer. Overall survival (OS) and radiographic progression-free survival (rPFS) were coprimary end points. Subgroup analysis of men aged ≥75 years (elderly) and men aged <75 years was pre-specified for the coprimary end points and adverse events (AEs). RESULTS: Among 609 elderly patients (35%) who participated in PREVAIL, median treatment duration was 16.6 and 5.0 months in the enzalutamide and placebo arms, respectively. In the elderly subgroup, OS was greater with enzalutamide than with placebo [32.4 months (95% confidence interval (CI) 27.7-not yet reached] versus 25.1 months (95% CI 22.6-28.0); hazard ratio (HR) = 0.61 (95% CI 0.47-0.79); P = 0.0001], as was rPFS [not yet reached (95% CI 12.3-not yet reached) versus 3.7 months (95% CI 3.6-5.3); HR = 0.17 (95% CI 0.12-0.24); P < 0.0001]. Irrespective of treatment assignment, incidence of AEs was similar between the two age groups, except for an overall higher incidence of falls among elderly patients than younger patients [84/609 (13.8%) versus 62/1106 (5.6%)] and among elderly patients receiving enzalutamide than those receiving placebo [61/317 (19.2%) versus 23/292 (7.9%)]. CONCLUSIONS: Elderly men benefited from treatment with enzalutamide in terms of OS and rPFS. Enzalutamide was well tolerated in the elderly subgroup and those aged <75 years. Age and enzalutamide treatment were associated with a higher incidence of falls. CLINICAL TRIAL IDENTIFIER: NCT01212991, ClinicalTrials.gov.