50-60 ml of heparinized peripheral blood was collected from each patient who completed the radiotherapy or CCRT treatment. Peripheral blood mononuclear cells (PBMCs) were isolated using Ficoll-Hypaque gradient centrifugation and cultured in X-VIVO 15 serum-free medium. CIK cells were generated using 1000 U/ml rhIFN-γ for the first day followed by stimulation with 100 ng/ml OKT-3, 1000 U/ml rhIL-2 and 100 U/ml IL-1a. Fresh medium containing 1,000 U/mL rhIL-2 was supplemented periodically during the culture. At 14 days, the CIK cells were harvested.
All NPC patients were treated with the either radical radiotherapy or with chemoradiotherapy. The overall median radiotherapy dose was 69.7 Gy (range, 68-70), the overall median dose per fraction was 2.19 Gy (range, 2.12-2.26) and the overall median duration of radiotherapy was 45 days (range, 42-49).
Induction chemotherapy (IC) was administered to the patients as follows: PF regimen (cisplatin and 5-Fu), TPF (docetaxel, cisplatin, and 5-Fu). Cisplatin regimen was used for concurrent chemoradiotherapy (CCRT). One month after completion of radiotherapy or CCRT, CIK group patients received immune cell infusion.
The fresh CIK cells were administered via intravenous infusion within 30 minutes. Before infusion, 50 to 60 mL heparinized peripheral blood was collected for the next cycle of CIK generation. Patients received at least four cycles of CIK cell treatment at two-week intervals.
Treatment-related AEs of CIK cell immunotherapy
The treatment-related AEs of CIK cells treatment include fever, fatigue, chills, vomiting, anemia, leucopenia and autoimmune disorder. Among the CIK group, AEs occurred in 14 cases (16.5%) during they received CIK cells infusion, 10 of which were fever, chills, and fatigue, at grade 1 or 2, and spontaneously resolved within 12 hours. Another four patients appeared leucopenia and recovered by symptomatic treatment. No infections, vomiting, allergic reactions or autoimmune disorder were observedfollowing infusion with CIK cells. No treatment-related serious AEs such as pneumonitis and treatment- related deaths appeared in any of the patients.
Prognosis of patients in the two groups
The median follow-up period for all patients was 78.3 months (range, 7.4-132.5 months). DFS and OS rates at 1, 3, and 5 years after curative radiotherapy or chemoradiotherapy were 94.1% (99.4%), 74.3% (89.0%), and 64.0 % (78.2%) for the whole study population.
Patients in the CIK group had a significantly enhanced DFS and OS compared to those in the control group. The median DFS and OS time were 76.6 and 81.2 months for patients in the CIK group compared to 61.3 and 68.6 months for patients in the control group, respectively.
The 1-, 3-, and 5-year DFS rates were 95.3%, 81.1%, and 72.3%, respectively, for the CIK group compared with 92.9%, 67.4%, and 55.6%, respectively, for the control group. The 1-, 3-, and 5-year OS rates were100%, 95.2%, and 88.9%, respectively, for the CIK group compared with 98.8%, 82.8%, and 67.4%, respectively, for the control group.
In conclusion, this retrospective study showed that adjuvant CIK cells treatment after curative radiotherapy or chemoradiotherapy exhibit a better survival improvement for stage II-IVB NPC patients than control group. Furthermore, this result showed that patients with advanced clinical stages might benefit more from adjuvant CIK immunotherapy.