PBMCs were isolated from random healthy donors, and NK cells were expanded. CD3+ T-cell–depleted PBMCs were expanded at a seeding concentration of 2×105 cells/mL in CellGro SCGM serum-free medium with 1% auto-plasma, 1×106 cells/mL irradiated (2,000 rad) autologous PBMCs, 10 ng/mL of monoclonal antibody to CD3 (OKT3 and 500 IU/mL of IL2 in an A-350N culture bag. NK cells were fed fresh medium with 500 IU/mL of IL2 every 2 days until they were harvested on day 14. K562 was obtained from the ATCC and cultured in RPMI-1640 medium supplemented with 10% FBS.
MG4101(allogenic NK cells) was administered intravenously one time (step 1) or repeatedly (step 2). Cohort 1 of step 1 was initiated with the infusion dose of 1×106 cells/kg of MG4101, and drug-related toxicities were assessed for 2 weeks. After safety assessment, cohort 3 (1×106 cells/kg, once weekly, triple infusion) and cohort 4 (3×106 cells/ kg, once weekly, triple infusion) were sequentially proceeded. Next, the escalated dose of 1×107 cells/kg was adoptively transferred to cohort 2 of step 1. When the single dose of 1×107 cells/kg was defined as safe, cohort 5 (1×107 cells/kg, once weekly, triple infusion) and cohort 6 (3×107 cells/kg, once weekly, triple infusion) of step 2 proceeded sequentially. In the case of body temperature above 38oC or toxicities greater than grade 2 in absolute neutrophil count, platelet count, hemoglobin, serum creatinine, total bilirubin, or liver aminotransferase, the administration of MG4101 was withheld.
In step 1 (cohort 1 and cohort 2), none of the subjects showed DLTs and all the toxicities were grade 1 or 2. Furthermore, a serial dose increase of MG4101 in step 1 did not seem to cause a proportionate increase in toxicity. The only grade 2 toxicity in our this was chills, which occurred in 1 patient from cohort 2. In step 2, repeated injection of a higher dose of MG4101 correlated with increased incidence of adverse events, but all remained between grades 1 and 2. MG4101-related GVHD was not observed in any of the subjects. As the maximum planned dose of this study was found to be tolerable, the MTD was not determined and 3×107 cells/kg was set as the MFD. Further, toxicity-related suspension of MG4101 injection did not occur during this study.
Responses to the MG4101 were evaluated in 17 patients, including 2 with lymphoma and 15 with advanced solid cancer. Three patients were not evaluable due to incomplete treatment or follow-up loss. As for the lymphoma patients, C1-01 exhibited stable disease (SD) and C4-01 had progressive disease (PD). Of the solid cancer patients, 7 (47%) had SD and 8 (53.0%) had PD. After MG4101 treatment, all of the lymphoma patients and 33% of solid cancer patients received further chemotherapies. The median progression-free survival (PFS) in patients with SD was 4 months (range, 2 to 18 months).
In contrast, administration of MG4101 reduced regulatory T cells and myeloid- derived suppressor cells and suppressed TGFþ production. In conclusion, administration of a large number of MG4101 cells was not only safe and feasible, but also exhibited efficacy in maintaining the effector arm of the host immune response.
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Scientific article publishing date :1/19/2016
Immucura identifier BSC21_223EN