Background Adoptive transfer of ex vivo expanded cytotoxic immune cells has become a viable strategy for treatment of malignant disease. Natural killer (NK)-92, a highly cytotoxic, IL2-dependent human NK cell-line, is an excellent candidate as an immunotherapeutic agent, being active, irradiation and IL2 deprivation, non-fir prolonged periods following toxic and non-immunogenic, and easily expanded. A number of clinical trials using, NK-92 for different indications are currently underway. The aim of this study was to develop current good manufacturing practice (cGMP) -compliant expansion methodology for NK-92. Methods The ability to expand NK-92 ex vivo was evaluated. Serum-free culture media, as well as media supplements (IL2, serum/plasma/ albumin), culture containers and feeding regimens were compared for their ability to support expansion, viability and cytotoxicity if NK-92 cells. Results NK-92 cells can be expanded in X-Vivo, 10 serum-free media with 450 U/mL, of rhIL2 (Proleukin), and 2.5% human serum/plasma to achieve concentrations sufficient to treat patients with > 5 x 10(10) cells. 1 be protocol involves cultures initiated at 2.5 x 10(5) cells/mL in 25 mL in 1 L Vuelife culture bags, with addition of fresh media plus IL2 every 3 days to maintain an optimal density of NK-92 cells for expansion. Daily disruption if cell aggregates enhances NK-92 cells expansion and viability during the culture period. Final yields of approximately 1.1- 1.3 x 10(6) cells/mL in it 1.2 L volume (1.36-1.56 x 10(9) cells; 218-250 fold expansion) over 15-17 days is achievable tinder cGMP-compliant conditions with > 85% viability. The feasibility of this approach hay been shown in ongoing clinical trials with NK-92. Discussion We describe a protocol that allows for > 200-fold expansion of NK-92 cells within a 2-2.5 week, period under GMP standards, in qualify and quantity suitable for clinical adoptive immunotherapy.
