(023) Neutropenia among patients with prostate cancer: Analysis of four US real world databases

Background: Occurrence of neutropenia in prostate cancer (PC) is associated with poor outcomes. The estimates of neutropenia occurrence in patients with PC are wide-ranging in literatures depending on patient characteristics and exposure to different therapies. It is important to understand the baseline risk of neutropenia for safety monitoring of therapies for PC.

Objectives: To determine the incidence of neutropenia and neutropenic fever among patients with PC and those exposed to antiandrogen therapies using real-world data (RWD).

Methods: Within each of 4 real-world databases, including IQVIA PharMetrics Plus, Optum’s de-identified Clinformatics® Data Mart Database, Optum® de-identified Electronic Health Record data set, and IQVIA Ambulatory Electronic Medical Record database, we generated cohorts of adult males with PC and identified incident events of neutropenia longitudinally. Outcomes of neutropenia included: 1) acquired neutropenia or unspecified leukopenia (AN/UL), 2) AN without codes for UL, and 3) neutropenic fever (NF) diagnosed during inpatient or emergency room (ER) visits. Incidence rates (IR) were calculated as the number of newly diagnosed neutropenia events observed during time-at-risk (TAR, 1 day after cohort entry to the end of observation) divided by total person-years at risk. Incidence proportions (IP) were calculated as the number of distinct people with neutropenia events divided by total number of people at risk. IR and IP were further estimated in patients who received treatment of recently approved androgen receptor inhibitors indicated for treatment of later stage PC (apalutamide or enzalutamide).

Results: The total number of patients with PC in each database ranged from 91,628 to 176,510. The IR of acquired AN/UL ranged from 0.70 to 2.05 per 100 person-years (100py) across databases, while the IP ranged from 1.08 to 3.50 per 100 persons (100p), with average TAR ranging from 19.6 – 21.7 months. Upon excluding codes for UL from the outcome, IR of AN ranged from 0.47 to 1.40 per 100py, and IP ranged from 0.74 to 2.41 per 100p. IRs for NF in inpatient/ER setting ranged from 0.36-0.68 per 100py and IP ranged from 0.58-1.16 per 100p. Among patients who received apalutamide or enzalutamide, IR ranged from 1.54 to 7.55 per 100py for AN/UL, 1.32 to 6.38 per 100py for AN, and 0.49 to 2.53 per 100py for NF, with the TAR ranging from 16.1 to 19.4 months.

Conclusions: This study of US RWD identified up to 3.5% patients with a new diagnosis of possible neutropenia following PC diagnosis. The occurrence is less frequent upon excluding codes for UL and restricting to NF in inpatient/ER setting. Patients in later stages of disease with exposure to antiandrogens were found to have higher incidence of neutropenia.