Toxoplasmosis in the Era of Targeted Immunotherapy: A Systematic Review of Emerging Cases Linked to Biologics and Small Molecules in Autoimmune Diseases, Oncology and Transplantation.

A systematic review of toxoplasmosis cases in patients receiving targeted immunotherapy with biologics or small molecules was performed. This systematic review searched for case reports, case series and observational studies in PubMed; last search was on 19 July 2025. The review identified 46 toxoplasmosis cases among patients receiving biologics (including CAR T-Cell Therapies) or small molecules for diverse autoimmune, oncologic and transplant conditions. These cases were reported from 18 countries, including the United States and several European countries. Most patients developed severe disease. Fifty percent (23/46) presented with cerebral toxoplasmosis, 33% (15/46) with ocular toxoplasmosis, 7% (3/46) with lymphadenopathy, 4% (2/46) with disseminated disease, 2% (1/46) with both cerebral and ocular disease, 2% (1/46) with pneumonic toxoplasmosis, and 2% (1/46) with severe fetal congenital toxoplasmosis. Among those were also four cases with fatal outcomes due to toxoplasmosis and eight cases with permanent ocular or neurological deficits. In addition, there was a case of fetal congenital toxoplasmosis that occurred despite maternal discontinuation of adalimumab five months before conception, resulting in elective pregnancy termination due to severe fetal cerebral disease. Overall, 44% (20/46) of cases were due to reactivation of chronic latent Toxoplasma infections and 39% (18/46) due to acute primary infections; 17% did not report this information. One case of disseminated acute toxoplasmosis was also identified after eating wild boar sausages, and two cases of severe acute ocular toxoplasmosis after eating undercooked venison meat, and undercooked unspecified type of meat respectively, while on small molecules or biologics. Details on the clinical presentations, management and clinical outcomes of these cases were reported. Recommendations for the management of toxoplasmosis in patients with targeted immunotherapies were also provided. Health care providers should consider toxoplasmosis in patients on biologics or small molecules who present with compatible clinical syndromes. Prompt diagnosis and treatment can be lifesaving.