Risk factors for treatment (tx) toxicity and discontinuation among patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) on androgen receptor targeted therapy (ART).

Abstract

135 Background: mCRPC is associated with (a/w) increased mortality among prostate cancer pts and new and safe txs are needed. In recent clinical trials, ARTs improved survival outcomes within this population, however, a significant portion will go on to discontinue tx. We aim to describe reasons for ART tx discontinuation and to identify predictors a/w increased risk of tx discontinuation due to tx toxicity or death. Methods: We performed a single-institution retrospective review of mCRPC pts on ART between 2010 and 2021. We screened for demographics, medical history, ART course, and tx side-effects. Our primary aim was to identify risk factors for tx discontinuation due to toxicity or death. Our secondary aim was to describe ART discontinuation among mCRPC. Fisher’s Exact was used to identify significant predictors of tx discontinuation due to toxicity or death. Significant outcomes were included in a multivariate logistic regression to determine odds ratios. Results: 133 pts with mCRPC started and discontinued ARTs. Among this cohort, 27 pts (20.3%) discontinued tx due to death or toxicity. Reasons for tx discontinuation are described in the table below. Significant predictors of tx discontinuation due to toxicity or death on bivariate analysis included pt-reported sepsis, hypertension (htn), weakness, falls, ECOG ≥2, and hospitalization during tx. Adjusting for confounders, pt-reported falls (OR 2.35; [0.91-2.59]; p=0.009), htn (OR 2.06; [0.94-2.21]; p=0.027), and weakness (OR 1.63; [0.59-2.72]; p=0.007) were a/w an increased risk of pt tx discontinuation from toxicity or death. Conclusions: Our results illustrate that the majority of mCRPC pts discontinued tx due to progression of disease. The data also indicates that mCRPC pts reporting new onset htn, falls, or weakness were more likely to discontinue tx due to toxicity or death. Early monitoring of this population is warranted to prolong duration of tx and prevent unnecessary txs. [Table: see text]