Real-world prevalence of adverse events with first-line systemic therapies among patients with metastatic castration-sensitive prostate cancer.

Background: The current guidelines for treating metastatic castration-sensitive prostate cancer (mCSPC) recommend treatment intensification of androgen deprivation therapy (ADT) with the addition of an androgen receptor pathway inhibitor (ARPI), with or without docetaxel. However, the adoption of these treatment options has been slow, leading to therapeutic inertia. This real-world study was conducted to investigate the occurrence of adverse events (AEs) among treated patients diagnosed with mCSPC in the United States.

Methods: This retrospective claim review estimated the occurrence of AEs among patients with mCSPC from January 2014 to June 2021 in the PharMetrics® Plus data set. The study focused on 10 common AEs (fatigue/asthenia, gastrointestinal [GI] AEs, skin/nail/hair AEs, immunodeficiency/thrombocytopenia, hot flash, sexual function AEs, anemia, hypertension, pain, and edema) known to occur in ≥10% of patients and ≥2% more prevalent than those treated with ADT alone as selected from the US Food and Drug Administration prescribing information and published results from clinical trials. Proportions of patients experiencing these AEs at Day 90, 180, and then every 180 days until month 30 during the follow-up period were estimated using cumulative hazard plots. Results were adjusted using inverse probability of treatment weighting (IPTW) across four treatment groups: ADT alone, ADT + nonsteroidal anti-androgen (NSAA) (bicalutamide, nilutamide, or flutamide), ADT + docetaxel, and ADT + ARPIs (abiraterone, apalutamide, or enzalutamide). ADT-alone cohort was the reference group for all comparisons.

Results: A total of 4145 patients were included (ADT alone: 2318, ADT + NSAA: 632, ADT + docetaxel: 471, ADT + ARPIs: 724). At baseline, median (interquartile range [IQR]) age was 64.3 (60.1-73.1) years; most common sites of metastasis were bone only (n = 1886, 45.5%) and node only (n = 1237, 29.8%); most used medications were pain medications (n = 2182, 52.6%) and corticosteroids (n = 1213, 29.3%). Median (IQR) duration of follow-up 10.2 (6.1-16.6) months in ADT alone, 6.7 (4.1-11.5) months in ADT + NSAA, 5.1 (4.3-5.9) months in ADT + docetaxel, and 11.0 (6.6-17.0) months in ADT + ARPI cohort. The reported AEs increased over time for all assessed AEs, across all treatment groups. Compared with ADT alone, no statistically significant difference in the proportion of patients with AEs was seen in the ADT + ARPI or ADT + NSAA cohorts at months 3 and 12; a significantly higher proportion of patients in the ADT + docetaxel cohort experienced 6 of the 10 assessed AEs at month 3 (fatigue/asthenia, GI AEs, skin/nail/hair AEs, immunodeficiency/thrombocytopenia, hot flash, anemia). During the follow-up period, on IPTW analysis, compared with ADT alone, a significantly higher proportion of patients experienced AEs with seven AEs in the ADT + docetaxel group (fatigue/asthenia, GI AEs, skin/nail/hair AEs, immunodeficiency/thrombocytopenia, hot flash, anemia, edema; p < 0.001 for all seven), three AEs in the ADT + ARPI group (hot flash, p = 0.05; anemia, p = 0.01; edema, p = 0.019), and one AE in the ADT + NSAA group (anemia, p = 0.029). The proportion of patients with sexual function AE did not significantly differ between the treatment groups and ADT alone.

Conclusion: Results of this large, real-world study demonstrated that all treatment groups experienced an increase in the rates of AEs over time, including ADT alone. Most AE rates with ADT + ARPIs were comparable with ADT + NSAA and not significantly different from ADT alone. ADT + docetaxel cohort was associated with significantly higher rates for all AEs over time except hypertension, sexual dysfunction, and pain. This study provides real-world evidence on AEs, beyond controlled clinical trials, and may assist healthcare providers to make better-informed decisions about disease management among patients with mCSPC.