Deep and Durable Prostate-specific Antigen Response to Darolutamide with Androgen Deprivation Therapy and Docetaxel, and Association with Clinical Outcomes for Patients with High- or Low-volume Metastatic Hormone-sensitive Prostate Cancer: Analyses of the Randomized Phase 3 ARASENS Study

BACKGROUND AND OBJECTIVE

Addition of darolutamide to androgen deprivation therapy (ADT) and docetaxel significantly improved overall survival (OS) in ARASENS (NCT02799602). Here we report on prostate-specific antigen (PSA) responses and their association with outcomes.

METHODS

ARASENS is an international, double-blind, phase 3 study in patients with metastatic hormone-sensitive prostate cancer (mHSPC) randomized to darolutamide 600 mg orally twice daily (n = 651) or placebo (n = 654), both with ADT + docetaxel. The proportion of patients with undetectable PSA (<0.2 ng/ml) and time to PSA progression (≥25% relative and ≥2 ng/ml absolute increase from nadir) were compared between groups in prespecified exploratory analyses. PSA outcomes by disease volume and the association of undetectable PSA with OS and times to castration-resistant prostate cancer (CRPC) and PSA progression were assessed in post hoc analyses.

KEY FINDINGS AND LIMITATIONS

The proportion of patients with undetectable PSA at any time was more than doubled with darolutamide versus placebo, at 67% versus 29% in the overall population, 62% versus 26% in the high-volume subgroup, and 84% versus 38% in the low-volume subgroup. Darolutamide delayed time to PSA progression versus placebo, with hazard ratios of 0.26 (95% confidence interval [CI] 0.21-0.31) in the overall population, 0.30 (95% CI 0.24-0.37) in the high-volume subgroup, and 0.093 (95% CI 0.047-0.18) in the low-volume subgroup. Undetectable PSA at 24 wk was associated with longer OS, with a hazard ratio of 0.49 (95% CI 0.37-0.65) in the darolutamide group, as well as longer times to CRPC and PSA progression, with similar findings in the disease volume subgroups.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Darolutamide + ADT + docetaxel led to deep and durable PSA responses in patients with high- or low-volume mHSPC. Achievement of undetectable PSA (<0.2 ng/ml) was correlated with better clinical outcomes.

PATIENT SUMMARY

For patients with metastatic hormone-sensitive prostate cancer being treated with androgen deprivation therapy and docetaxel, PSA (prostate-specific antigen) became undetectable (below 0.2 ng/ml) in 67% of those also receiving darolutamide versus 29% of patients also receiving placebo. On average, patients achieving undetectable PSA lived longer than patients with detectable PSA.

Safety and tolerability of long-term treatment with darolutamide in patients with metastatic castration-resistant prostate cancer

BACKGROUND

In patients with metastatic castration-resistant prostate cancer, darolutamide was well tolerated for 25 months, but minimal long-term safety data are available.

METHODS

Treatment-emergent adverse events (TEAEs) for patients receiving darolutamide for a median of 38 months (n = 13) are described in this pooled analysis of individual patient data from phase 1/2 studies.

RESULTS

All patients reported TEAEs (mostly grade 1/2). The most common TEAEs were diarrhea, abdominal pain, and nausea. Serious TEAEs were reported in six patients (none related to darolutamide). All treatment-related TEAEs (n = 5) were grade 1.

CONCLUSIONS

Long-term darolutamide treatment was well tolerated; no new safety signals observed. In patients with mCRPC, long-term darolutamide treatment was well tolerated and no new safety signals were observed. These findings are consistent with previous reports, demonstrating a favorable safety and tolerability profile of darolutamide.

Early prostate-specific antigen response among Black and non-Black patients with advanced prostate cancer treated with apalutamide

Aim: To assess reduction in prostate-specific antigen (PSA) levels among Black and non-Black patients treated with apalutamide for non-metastatic castration-resistant prostate cancer (nmCRPC) or metastatic castration-sensitive prostate cancer (mCSPC). Patients & methods: Patients were identified from electronic medical data. PSA reduction (≥50%, ≥90% or below 0.2 ng/ml) after apalutamide initiation was assessed. Results: A total of 313 patients with nmCRPC and 260 patients with mCSPC were identified. The majority of patients treated with apalutamide achieved a 90% reduction in PSA regardless of indication or race. The proportion of patients achieving a PSA reduction at any level was similar among Black and non-Black patients and was consistent with apalutamide phase III trials. Conclusion: In routine clinical practice, apalutamide consistently produced reduction in PSA levels in Black and non-Black men with nmCRPC or mCSPC.

Apalutamide, Darolutamide and Enzalutamide for Nonmetastatic Castration-Resistant Prostate Cancer (nmCRPC): A Critical Review

Nonmetastatic castration-resistant prostate cancer (nmCRPC) represents a condition in which patients with prostate cancer show biochemical progression during treatment with androgen-deprivation therapy (ADT) without signs of radiographic progression according to conventional imaging. The SPARTAN, ARAMIS and PROSPER trials showed that apalutamide, darolutamide and enzalutamide, respectively, prolong metastasis-free survival (MFS) and overall survival (OS) of nmCRPC patients with a short PSA doubling time, and these antiandrogens have been recently introduced in clinical practice as a new standard of care. No direct comparison of these three agents has been conducted to support treatment choice. In addition, a significant proportion of nmCRPC on conventional imaging is classified as metastatic with new imaging modalities such as the prostate-specific membrane antigen positron emission tomography (PSMA-PET). Some experts posit that these “new metastatic” patients should be treated as mCRPC, resizing the impact of nmCRPC trials, whereas other authors suggest that they should be treated as nmCRPC patients, based on the design of pivotal trials. This review discusses the most convincing evidence regarding the use of novel antiandrogens in patients with nmCRPC and the implications of novel imaging techniques for treatment selection.