Radiographic Progression Without Corresponding Prostate-specific Antigen Progression in Patients with Metastatic Castration-sensitive Prostate Cancer Receiving Apalutamide: Secondary Analysis of the TITAN Trial

Wataru Fukuokaya ¹, Takafumi Yanagisawa ¹, Keiichiro Mori ¹

⁰Department of Urology, The Jikei University School of Medicine, Tokyo, Japan.

European Urology Oncology +

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April 30, 2024

View abstract on PubMed

Summary

In metastatic castration-sensitive prostate cancer (mCSPC) treated with apalutamide, radiographic progression can occur without prostate-specific antigen (PSA) progression. This suggests imaging is crucial for monitoring treatment response in mCSPC patients.

Area Of Science

Oncology
Medical Imaging
Prostate Cancer Research

Background

Androgen deprivation therapy (ADT) is a standard treatment for prostate cancer.
Treatment resistance in prostate cancer is often indicated by prostate-specific antigen (PSA) progression, followed by radiographic progression.
The relationship between PSA and radiographic progression is not fully understood in metastatic castration-sensitive prostate cancer (mCSPC) treated with androgen receptor pathway inhibitors.

Purpose Of The Study

To evaluate the association between radiographic progression, PSA progression, and outcomes in mCSPC patients treated with apalutamide.
To investigate discordant progression (radiographic progression without concurrent PSA progression) in the context of apalutamide therapy.

Main Methods

Analysis of individual participant data from the TITAN trial (N=326) focusing on patients with radiographic progression.
Definition of discordant progression based on Prostate Cancer Working Group 2 criteria.
Exploration of the association between discordant progression and radiographic progression-free survival using multivariable logistic regression.

Main Results

Discordant progression occurred in 52.2% of patients treated with apalutamide plus ADT, compared to 27.5% in the placebo plus ADT group (p < 0.001).
Multivariable analysis indicated that discordant progression was associated with apalutamide treatment.
Evidence suggests an association between discordant progression and shorter radiographic progression-free survival.

Conclusions

Nearly half of mCSPC patients on apalutamide experiencing radiographic progression did so without concurrent PSA progression.
Relying solely on PSA monitoring may be insufficient for assessing disease activity in mCSPC patients treated with apalutamide.
Regular radiographic imaging is important for monitoring mCSPC patients on apalutamide therapy.

Keywords:

Apalutamide Metastatic castration-sensitive prostate cancer Prostate-specific antigen Radiographic progression

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