LHRH sparing therapy in patients with chemotherapy-naïve, mCRPC treated with abiraterone acetate plus prednisone: results of the randomized phase II SPARE trial.

BACKGROUND: Although the benefit of androgen deprivation therapy (ADT) continuation in metastatic castration-resistant prostate cancer (mCRPC) remains controversial, clinical evidence is lacking. Recent results indicated that treatment with abiraterone acetate (AA) plus prednisone (P) further suppresses serum testosterone levels over ADT alone, suggesting that continuation of ADT in the treatment of mCRPC may not be necessary. METHODS: In this exploratory phase 2 study, mCRPC patients were randomized with a 1:1 ratio to receive either continued ADT plus AA + P (Arm A) or AA + P alone (Arm B). The primary endpoint was the rate of radiographic progression-free survival (rPFS) at month 12. Secondary endpoints included PSA-response rate, objective response, time to PSA progression and safety. RESULTS: A total of 68 patients were equally randomized between the two study arms. Median testosterone-levels remained below castrate-levels throughout treatment in all patients. According to the intention-to-treat analysis the rPFS rate was 0.84 in Arm A and 0.89 in Arm B. Moderate and severe treatment-emergent adverse events were reported for 72% of the patients in Arm A and for 85% of the patients in Arm B. CONCLUSIONS: AA + P treatment without ADT may be effective in mCRPC patients and ADT may not be necessary in patients receiving AA + P.

[Early- vs. late-onset treatment using abiraterone acetate plus prednisone in chemo-naïve, asymptomatic or mildly symptomatic patients with metastatic CRPC after androgen deprivation therapy]. / Frühe vs. spätere Therapie mit Abirateron plus Prednison bei chemotherapie-naiven, asymptomatischen bis mild symptomatischen Patienten mit metastasiertem CRPC nach Androgendeprivation.

BACKGROUND: Abiraterone acetate (AA) is a prodrug of abiraterone, which is an irreversible inhibitor of 17α-hydroxylase/C17, 20-lyase. Since 2011, abiraterone acetate has been available in combination with prednisone/prednisolone (AA + P) for the treatment of metastatic castration-resistant prostate cancer (mCRPC) after pre-treatment with docetaxel, and since 2012 for the treatment of chemotherapy-naïve asymptomatic or mildly symptomatic mCRPC patients. A revision of the guidelines of the European Association of Urology in 2014 redefining castration resistance gave rise to the question of when the treatment of mCRPC with abiraterone acetate plus prednisone should be initiated after prior hormone treatment and how successful it would be. This led us to observe an early-onset AA + P therapy cohort (EC) and a late-onset therapy cohort (LC) of patients. PATIENTS AND METHODS: We designed a combined retrospective and prospective, multicentre, non-interventional two-cohort study to obtain data on the effectiveness and safety of an early-onset AA + P therapy in mCRPC patients in the clinical routine compared to a late therapy onset. The EC comprised patients who received AA + P immediately after castration resistance without a prior first-generation antiandrogen such as bicalutamide or flutamide. The LC included patients who, after castration resistance had occurred, started treatment with AA + P only after unsuccessful treatment with a first-generation antiandrogen. Patients with mCRPC who received AA + P therapy according to the physician's routine clinical practice decision were considered. The patients were consecutively included in the study on the basis of their medical records, with the treatment decision having been made independently of and before patient enrolment. Patients were documented or followed from the beginning of AA + P therapy until the start of a carcinoma-specific systemic follow-up therapy (retrospectively if before and prospectively if after start of data collection). Effectiveness analyses were done for all patients with at least two AA + P administrations and safety analyses for all treated patients. RESULTS: Of the 159 patients included, 44 received early therapy and 105 received later therapy with AA + P. 10 patients could not be clearly assigned and were summarised in a third cohort (missed early-onset therapy assignment; MEC). 56/159 patients (35.2 %) were still alive at study start and 103/159 patients (64.8 %) had already deceased (31/44 [70.5 %] in EC, 64/105 [61.0 %] in LC, and 8/10 [80.0 %] in MEC). 24/159 patients (15.1 %) were documented both retrospectively and prospectively. The median duration of AA + P treatment was 11.3 months for EC, 12.0 months for LC, and 8.3 months for MEC patients. The median time to next systemic cancer therapy or death was 12.3 months for EC and 12.8 months for LC patients (p = 0.2820). The median time to the next systemic cancer therapy alone (i. e. without the event 'death') was 22.7 months for EC and 23.3 months for LC patients (p = 0.5995). Median overall survival (OS) was 22.3 months for EC and 39.2 months for LC patients (p = 0.0232). The incidence of serious adverse events (SAEs) was low. SAEs occurred in 3/44 EC (6.8 %), 4/105 LC (3.8 %), and 1/10 MEC patients (10.0 %). One SAE in EC and one in LC resulted in death. CONCLUSIONS: In contrast to the new definition of castration resistance, AA + P was still more frequently used in daily clinical practice during the study observation period in patients treated with antiandrogens of the first generation after occurrence of castration resistance. Nevertheless, AA + P therapy appears to be effective and well tolerated during clinical routine in mCRPC patients. A comparison of the study results with earlier 'real-world' studies, however, has to take limiting factors into account. The observed difference in median overall survival might be explained by the imbalance of baseline characteristics between both cohorts with regard to number of patients, patients already deceased at start of documentation, patients with visceral metastases and patients with opioids at start of AA + P. For these reasons, patients in the EC initially might have had a poorer prognosis. A prospective randomised and controlled clinical trial would therefore be necessary to assess a possible difference in overall survival and response of the AA + P treatment with respect to therapy onset.

Intermittent hormonal therapy in the treatment of metastatic prostate cancer: a randomized trial.

UNLABELLED: Study Type - Therapy (RCT) Level of Evidence 1b. What's known on the subject? and What does the study add? Intermittent androgen deprivation therapy (ADT) involves cycling ADT, allowing hormonal recovery during off-treatment periods. This could lead to a better quality of life during off-treatment periods and could delay progression to castration resistance. Safety and feasibility of intermittent ADT have been shown but tolerability and health-related quality of life improvement have been suggested but questioned by others. Results from randomized trials, including relapsing or mixed populations, have suggested intermittent ADT to be as effective as continuous ADT. In this study of only metastatic patients, no statistical difference in either overall survival or progression-free survival was shown between intermittent and continuous ADT and suggests that intermittent might be as safe as continuous castration. It could be an option in highly responding and well-informed metastatic patients even if no clear benefit in health-related quality of life was shown. This intermittent modality could be of interest in metastatic patients with significant treatment-induced side-effects. OBJECTIVE: • To compare intermittent androgen deprivation therapy (ADT) and continuous ADT after 6 months of induction of ADT in patients with metastatic prostate cancer (PCa). PATIENTS AND METHODS: • This is an open-label randomized multi-centre study conducted in 58 centres in Europe. • Patients with metastatic PCa and prostate-specific antigen (PSA) level >20 ng/mL at selection were randomized after 6 months of induction of ADT (leuprorelin and flutamide) if PSA level had decreased below 4 ng/mL. • Patients received either continuous or intermittent ADT. All patients were treated until signs of disease progression under treatment or until study end with a monthly central PSA determination and follow-up visits were performed every 3 months. • The primary endpoint was overall survival. Secondary endpoints included progression-free survival, health-related quality of life (QLQ C30 questionnaire) and safety criteria. RESULTS: • Of 383 selected patients, 173 had a PSA level below 4 ng/mL after 6 months of induction of ADT and were randomized. Median overall survival (52 vs 42 months, P= 0.75) and median progression-free survival (15.1 vs 20.7 months, P= 0.74) were not significantly different between continuous and intermittent ADT. • Although some differences in quality of life were observed, most of the functional and symptom scales showed no significant difference between the two groups. • Significantly fewer treatment-emergent adverse events occurred in the intermittent group (P= 0.042), with the incidence of headache and hot flushes also lower. CONCLUSIONS: • This first randomized trial comparing continuous with intermittent ADT in metastatic PCa suggests that intermittent ADT might be as safe as continuous ADT. • It could be an option in highly responding and well-informed patients even if no clear benefit in health-related quality of life was shown.