Abstract
BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) is a life-threatening infection occurring in patients receiving bendamustine. The poorly defined incidence, particularly when utilizing polymerase chain reaction (PCR)-based diagnostic techniques, precipitates unclear prophylaxis recommendations. Our objective was to determine the cumulative incidence of PJP diagnosed by single copy target, non-nested PCR in patients receiving bendamustine. METHODS: Patients were evaluated for PJP from initiation of bendamustine through 9 months after the last administration. The cumulative incidence of PJP was estimated using the Aalen-Johansen method. Cox proportional hazard models were used to demonstrate the strength of association between the independent variables and PJP risk. RESULTS: This single-center, retrospective cohort included 486 adult patients receiving bendamustine from 1 January 2006 through 1 August 2019. Most patients received bendamustine-based combination therapy (n = 461, 94.9%), and 225 (46.3%) patients completed six cycles. Rituximab was the most common concurrent agent (n = 431, 88.7%). The cumulative incidence of PJP was 1.7% (95% CI 0.8%-3.3%, at maximum follow-up of 2.5 years), after the start of bendamustine (n = 8 PJP events overall). Prior stem cell transplant, prior chemotherapy within 1 year of bendamustine, and lack of concurrent chemotherapy were associated with the development of PJP in univariate analyses. Anti-Pneumocystis prophylaxis was not significantly associated with a reduction in PJP compared to no prophylaxis (HR 0.37, 95% CI (0.05, 3.04), p = 0.36). CONCLUSIONS: Our incidence of PJP below 3.5%, the conventional threshold for prophylaxis implementation, indicates routine anti-Pneumocystis prophylaxis may not be necessary in this population. Factors indicating a high-risk population for targeted prophylaxis require further investigation.