Switch from abiraterone plus prednisone to abiraterone plus dexamethasone at asymptomatic PSA progression in patients with metastatic castration-resistant prostate cancer.

OBJECTIVE: To evaluate the effects of switching from prednisone (P) to dexamethasone (D) at asymptomatic prostate-specific antigen (PSA) progression in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone acetate (AA). MATERIALS AND METHODS: Among 93 patients treated with AA between January 2013 and April 2016 in our institution, 48 consecutive asymptomatic patients with mCRPC, who experienced biochemical progression on treatment with AA+P 10 mg/day, were included. A corticosteroid switch to AA+D 0.5 mg/day at PSA increase was administered until radiological and/or clinical progression. The primary endpoint was progression-free-survival (PFS). A prognostic score based on independent prognostic factors was defined. RESULTS: The median time to PSA progression on AA+P was 8.94 months. The median PFS on AA+D and AA+corticosteroids (P then D) was 10.35 and 20.07 months, respectively. A total of 56.25% of patients showed a decrease or stabilization in PSA levels after the switch. In univariate analysis, three markers of switch efficiency were significantly associated with a longer PFS: long hormone-sensitivity duration (≥5 years; median PFS 16.62 vs 4.17 months, hazard ratio [HR] 0.30, 90% confidence interval [CI] 0.16-0.56); low PSA level at the time of switch (<50 ng/mL; median PFS 15.21 vs 3.86 months, HR 0.33, 90% CI 0.18-0.60); and short time to PSA progression on AA+P (<6 months; median PFS 28.02 vs 6.65 months, HR 0.41 (90% CI 0.21-0.81). In multivariate analysis, hormone sensitivity duration and PSA level were independent prognostic factors. CONCLUSION: A steroid switch from P to D appears to be a safe and non-expensive way of obtaining long-term responses to AA in selected patients with mCRPC. A longer PFS has been observed in patients with previous long hormone sensitivity duration, and/or low PSA level and/or short time to PSA progression on AA+P.

Adverse events reporting in phase 3 oncology clinical trials of checkpoint inhibitors: A systematic review.

INTRODUCTION: This study aimed at exploring adverse events (AEs) reporting in cancer trials involving immune checkpoint inhibitors (ICIs). METHOD: A systematic review on how ICIs phase 3 trials follow TRIO and 2004 CONSORT harms extension recommendations referring to toxicity was performed by two independent reviewers. RESULTS: Among 46 trials included, 74 % did not present separately grade 3 and grade 4 AEs. Timing of onset and duration were reported in 30 % and 28 %, respectively. AEs occurring in <10 % of patients were only reported in 35 % of studies. Patient-related outcomes (PROs) were analyzed in only 17 % of reports. Eight articles qualified the toxicity profile as "manageable", "tolerable", "well tolerated" or "favorable" despite reporting a rate of grade 3-4 greater than 33 %. CONCLUSION: Reporting toxicity results is crucial. However, toxicity reporting is highly incomplete in clinical trials. Guidelines, new metrics and incorporation of PROs are needed for a comprehensive knowledge of toxicity profile.

Pharmacokinetic/Pharmacodynamic Relationship of Enzalutamide and Its Active Metabolite N-Desmethyl Enzalutamide in Metastatic Castration-Resistant Prostate Cancer Patients.

INTRODUCTION: Enzalutamide (ENZA) is an oral androgen receptor inhibitor approved by the Food and Drug Administration and the European Medicines Agency for the treatment of metastatic and nonmetastatic castration-resistant prostate cancer (CRPC). ENZA is extensively metabolized by cytochrome P450 3A4 into N-desmethyl ENZA (NDE), an active metabolite. We aimed to explore the pharmacokinetic/pharmacodynamic relationship for ENZA and NDE in metastatic CRPC patients from a real-world setting. PATIENTS AND METHODS: Trough plasma concentration (Ctrough) of ENZA and NDE were assayed using liquid chromatography coupled with UV detection. The relationship between ENZA, NDE, and composite (ENZA with NDE) plasma concentration and requirement of ENZA dose reduction was investigated using the Mann-Whitney test. A survival univariate analysis was conducted to explore association between progression-free survival (PFS), overall survival (OS), and plasma Ctrough (ENZA, NDE, and composite). RESULTS: Twenty-two metastatic CRPC patients treated with ENZA (median age, 75.5 years; 13 patients (59%) with Eastern Cooperative Oncology Group status 0-1) were prospectively included. Mean plasma Ctrough of ENZA and NDE were 12.4 ± 3.0 µg/mL and 8.8 ± 2.1 µg/mL, respectively. Neither PFS nor OS were statistically associated with ENZA, NDE, or composite plasma Ctrough. In 4 patients (18%) who required ENZA dose reduction because of severe clinical toxicity, an increased ENZA plasma Ctrough was observed compared with 18 remaining patients (16.1 ± 2.4 µg/mL vs. 11.6 ± 2.6 µg/mL, respectively; P = .027). CONCLUSION: The low interindividual variability in ENZA and NDE Ctrough and the lack of relationship with survival do not support the need for plasma drug monitoring. Severe asthenia might be related to higher exposure and could be improved by decreasing ENZA dosing.