Off-Label Use of Monoclonal Antibodies in Developing Countries

Rituximab is used in different hematologic, rheumatic, neurologic, and renal disorders. As the clinical applications of this agent continue to expand, its use, including off-label use, requires careful and consistent evaluation. Off-label use should not be considered inappropriate by default, as it may be supported by clinical evidence or current authoritative guidelines. To what extent does rituximab prescribing conform to established clinical guidelines and approved indications, and what deficiencies exist in the implementation of prescribing criteria and pretreatment safety assessments? A prospective observational evaluation of rituximab utilization was conducted at a tertiary academic hospital in Tehran, Iran, over a 6-month period from April to October, 2023. We collected data on patients who received rituximab, including demographic characteristics, clinical indications, classification of use as on-label, off-label, or outside the applicable protocol, adherence to relevant prescribing criteria, and documentation of pretreatment screening for hepatitis B virus, hepatitis C virus (human immunodeficiency virus (HIV)), HIV, and tuberculosis. Among the 171 patients who received rituximab, the mean age was 45.3 years, and 66.7% were female. Approximately 40 distinct indications were identified. The most common indications were granulomatosis with polyangiitis (22 patients, 12.9%), rheumatoid arthritis (21, 12.3%), multiple sclerosis (20, 11.7%), diffuse large B-cell lymphoma (19, 11.1%), and lupus nephritis (9, 5.3%). Overall, 37.4% of rituximab uses were classified as on-label, 58.5% as off-label, and 4.1% as outside the applicable protocol. Conclusions: Rituximab was widely used in clinical practice; however, its implementation protocols and safety-monitoring practices varied considerably. In light of these findings, it is important to distinguish between off-label use and inappropriate use, and to ensure that treatment decisions are evaluated against current evidence, clinical guidelines, and indication-specific criteria.