Safeguarding Lungs: Evaluating Pneumocystis Pneumonia Prophylaxis in Lymphoma Patients Receiving Rituximab-Inclusive Therapies

Background: Pneumocystis pneumonia (PCP) is an opportunistic fungal infection, which is frequently observed in immunocompromised patients. Although T-cell immunity is classically related to Pneumocystis defense, recent data support roles for B lymphocytes in the development of PCP in animals, and we have observed several cases of PCP in patients receiving rituximab. These observations prompted a systematic review and meta-analysis of our experience to see the efficacy of PCP prophylaxis (TMP-SMX) in lymphoma patients receiving rituximab. The efficacy of PCP prophylaxis in this population remains a subject of clinical interest. Research Question: To evaluate the effect of PCP prophylaxis compared to no prophylaxis on the risk of developing PCP in lymphoma patients receiving rituximab. Methods: We conducted meta-analysis including six retrospective cohort studies that compared the incidence of PCP in lymphoma patients receiving rituximab with and without prophylaxis. The cohort studies with incept up to January 2023 were retrieved from databases including PubMed, Google Scholar, EMBASE, PLOS ONE, Cochrane, and ClinicalTrials.gov. Data extraction was done using a spreadsheet, and data analysis was done using RevMan 5.4.1 for meta-analysis. Results: The analysis included 2304 patients, with 571 receiving PCP prophylaxis and 1733 did not receive prophylaxis. Studies reporting results of PCP prophylaxis were included. Enrolled studies were quality assessed with Newcastle-Ottawa Scale. The incidence of PCP was significantly lower in the prophylaxis group (3 out of 571) compared to the no prophylaxis group (67 out of 1733). The pooled risk ratio (RR) was 0.23 [95% CI, 0.09 to 0.58], indicating a 77% reduction in the risk of PCP with prophylaxis. Conclusion: The clinical course of cases of PCP in patients treated with rituximab can be quite fulminant, with significant mortality. Primary prophylaxis should be considered in patients at risk. PCP prophylaxis significantly decrease the risk of PCP in lymphoma patients receiving rituximab-based therapies, with a pooled risk ratio of 0.23.