[An exploratory clinical study of the efficacy and safety of tumor-infiltrating lymphocytes in the treatment of metastatic osteosarcoma]

Objective: To explore the safety and efficacy of tumor-infiltrating lymphocytes (TILs) extracted from tumor tissue in patients with pulmonary metastasis of osteosarcoma, the TILs were amplified in vitro to reach clinical dosage and reinfused to the patients combined with high-dose interleukin 2 (IL-2). Methods: Twelve subjects with pathologically diagnosed osteosarcoma were enrolled from December 2019 to June 20, 2021 in Shanghai General Hospital. All subjects progressed with metastasis after standard chemotherapy and failed multiple lines of treatments. Fresh tumor tissue was obtained from the metastatic site and extracted and amplified by Good Manufacturing Practice (GMP) workshop to produce TILs to clinical treatment dosage (10⁹-10¹¹). High-dose IL-2 (100 000-200 000 U/kg) was administered immediately after autogenous TILs infusion to promote the activation, proliferation and antitumor cytolytic activity in vivo. Adverse events (AE) were graded according to Common Terminology Criteria for Adverse Events (CTCAE) standard and tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Results: One patient did not receive treatment due to failure in isolating TILs, total of 11 patients received a single re-infusion of autologous TILs. There were 10 males and 1 female with a median age of 19.9 years (12-33 years). Six of these patients received higher dose levels of 1.0×10¹⁰ TILs. The 11 patients were followed-up for 1 to 13 months and tolerated well. The most common adverse events reported were fever (10/11), constipation (3/11) and elevated gamma-glutamyl transferase (GGT) (3/11). The high incidence of fever was due to the IL-2 infusion. All patients experienced a transient drop in lymphocyte count and leukopenia leading to non-myeloid ablative lymphocyte clearance. The AE included grade 4 hematologic toxicity, including 8 cases of lymphocytopenia, 2 cases of neutropenia and 1 case of thrombocytopenia. No AE of neurotoxicity occurred. Of all the 11 patients, 9 patients got stable disease (SD) and 2 patients had progressive disease (PD). The disease control rate was 9/11. The median duration of SD was more than 4 months, and the maximum tumor volume decreased by close to 20%. Patient number 9 had sustained SD status for more than 6 months. Conclusions: TILs with in vitro expansion ability could be isolated from tumor tissues of advanced osteosarcoma patients. TILs amplified and reinfused in vitro have anti-osteosarcoma activity.