The dataset reports the clinical and paraclinical characteristics of the 9 patients treated with T cell therapy included in the final article, including gender, age at diagnosis, underlying hematological conditions, neurological symptoms at diagnosis, JCV viral load in the cerebrospinal fluid, number of T cell infusions, and neurological outcome following treatment. Nuclear magnetic resonance data are not reported. The aim of this study was to analyze the safety and carry out preliminary evaluation of the efficacy of polyomavirus JC (JCPyV) -specific T cell therapy in a cohort of hematological patients with PML. 9 patients with a diagnosis of "definite PML" who were showing progressive clinical deterioration received JCPyV-specific T cells. Cell lines were expanded from autologous or allogenic peripheral blood mononuclear cells by stimulation with JCPyV antigen-derived peptides. In the evaluable patients, an increase in the frequency of circulating JCPyV-specific lymphocytes was observed, with a decrease or clearance of JCPyV viral load in cerebrospinal fluid. In responsive patients, transient appearance of punctate areas of contrast enhancement within, or close to, PML lesions was observed, which was interpreted as a sign of immune control and which regressed spontaneously without the need for steroid treatment. Six of 9 patients achieved PML control, with 5 alive and in good clinical condition at their last follow-up. None of the patients experienced treatment-related adverse events.

Funding: Ricerca Corrente 2019, Ministry of Health (Italy)