Simplified Method of the Growth of Human Tumor Infiltrating Lymphocytes in Gas-permeable Flasks to Numbers Needed for Patient Treatment

Adoptive cell therapy of metastatic melanoma with autologous tumor infiltrating lymphocytes (TIL) is clinically effective, but TIL production can be challenging. Here we describe a simplified method for initial TIL culture and rapid expansion in gas-permeable flasks. TIL were initially cultured from tumor digests and fragments in 40 mL capacity flasks with a 10 cm² gas-permeable silicone bottom, G-Rex10. A TIL rapid expansion protocol (REP) was developed using 500 mL capacity flasks with a 100 cm² gas-permeable silicone bottom, G-Rex100. TIL growth was successfully initiated in G-Rex10 flasks from tumor digests from 13 of 14 patients and from tumor fragments in all 11 tumor samples tested. TIL could then be expanded to 8-10×10⁹ cells in a 2-step REP that began by seeding 5×10⁶ TIL into a G-Rex100 flask, followed by expansion at day 7 into 3 G-Rex100 flasks. To obtain the 30-60×10⁹ cells used for patient treatment, we seeded 6 G-Rex100 flasks with 5×10⁶ cells and expanded into 18 G-Rex100 flasks. Large-scale TIL REP in gas-permeable flasks requires approximately 9-10 L of media, about 3-4 times less than other methods. In conclusion, TIL initiation and REP in gas-permeable G-Rex flasks require fewer total vessels, less media, less incubator space, and less labor than initiation and REP in 24-well plates, tissue culture flasks, and bags. TIL culture in G-Rex flasks will facilitate the production of TIL at the numbers required for patient treatment at most cell processing laboratories.