Rituximab and Cancer Chemotherapeutic Drugs: Implications for Post-COVID-19 Pulmonary Fibrosis Risk – A Nationwide Cohort Study


The COVID-19 pandemic has had a profound impact on global health, with millions of individuals affected by the virus and its complications. One of the emerging concerns is the long-term effects of COVID-19, particularly the development of pulmonary fibrosis, a condition characterized by the scarring of lung tissue.

In this nationwide cohort study, we investigated the association between commonly-used medications and the risk of post-COVID-19 pulmonary fibrosis, with a focus on rituximab, cancer chemotherapeutic drugs, corticosteroids, and amiodarone.

Pulmonary Fibrosis: A Growing Health Concern

Pulmonary fibrosis is a serious and potentially life-threatening condition where lung tissue becomes scarred and stiff, leading to impaired lung function and difficulty in breathing. While the annual incidence of idiopathic pulmonary fibrosis in the general US population was reported at 93.7 per 100,000 person-years in 2011, there has been a steady increase in overall pulmonary fibrosis cases. Recent studies suggest that up to eleven percent of patients who have been hospitalized with COVID-19 may develop pulmonary fibrosis, making it a growing health concern.

Medications and Pulmonary Fibrosis Risk

A multitude of evidence points to various medications’ potential involvement in the development of pulmonary fibrosis. Cancer chemotherapeutic drugs, such as bleomycin and gemcitabine, are known to have lung toxicity and fibrotic effects. Similarly, rituximab, a monoclonal antibody used to treat autoimmune and lymphoproliferative disorders, has been associated with lung toxicity and fibrosis. Immunomodulatory medications like corticosteroids, commonly used for inflammatory lung conditions, may also have implications in fibrosis development.

Rituximab and Pulmonary Fibrosis Risk

Rituximab, which targets CD20-positive B cells, has shown an increased risk of severe post-COVID-19 outcomes. Additionally, studies have linked the use of rituximab to lung toxicity and fibrosis. The mechanism by which rituximab increases the risk of post-COVID-19 fibrosis is not fully understood, but it may involve the drug’s immunosuppressive effects and disruption of viral clearance mechanisms. The risk of pulmonary fibrosis is further amplified when rituximab is used in COVID-positive patients, suggesting a possible synergistic effect between the medication and SARS-CoV-2 infection.

Cancer Chemotherapy and Pulmonary Fibrosis Risk

Patients with cancer are vulnerable to severe COVID-19 outcomes, and cancer chemotherapy, known for its immunosuppressive effects, may increase the risk of post-COVID-19 pulmonary fibrosis. Several mechanistic studies have demonstrated that chemotherapeutic agents can activate fibroblast proliferation and collagen synthesis, key processes in the development of pulmonary fibrosis.

Corticosteroids and Pulmonary Fibrosis Risk

Corticosteroids, widely used as immunomodulatory drugs, were associated with a marginally increased risk of post-COVID-19 pulmonary fibrosis when compared to matched controls. The risk was higher in COVID-positive individuals receiving corticosteroid therapy compared to the COVID-negative cohort, suggesting a potential role in propagating fibrosis following disruption of innate immunologic mechanisms responsible for viral clearance.

Amiodarone and Pulmonary Fibrosis Risk

Amiodarone, a drug used to treat heart rhythm disorders, has been linked to pulmonary fibrosis, but its use did not appear to increase the risk of post-COVID-19 fibrosis in our study. However, amiodarone did amplify the risk of pulmonary fibrosis in the absence of SARS-CoV-2 positivity, highlighting its known association with fibrotic lung disease.

Implications for Public Health and Clinical Practice

Our study provides valuable insights into the potential risks of commonly-used medications in the development of post-COVID-19 pulmonary fibrosis. The observed increased risk, independent of age, suggests that clinicians should be cautious when prescribing these medications to individuals with a history of COVID-19. Further research is needed to fully understand the mechanisms behind the association between these medications and pulmonary fibrosis to inform better treatment and management strategies for patients at risk.


Post-COVID-19 pulmonary fibrosis is a significant concern, with emerging evidence pointing to an association with several commonly-used medications. Rituximab and cancer chemotherapeutic drugs appear to increase the risk of pulmonary fibrosis in COVID-positive individuals, while corticosteroids may marginally increase the risk. Our findings emphasize the importance of vigilance and further research to inform clinical decision-making and public health policies regarding the use of these medications in individuals with a history of COVID-19. Understanding the mechanisms behind these associations is critical to develop targeted therapies and improve patient outcomes in the face of this ongoing global health challenge.



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