Infusion of Donor Derived Cytokine Induced Killer Cells May Induce Clinical Remission with Limited GVHD in Patients Relapsing after Allogeneic Stem Cell Transplantation.

Cytokine induced killer cells (CIK) are T/NK cells with demonstrated anti-tumoral activity but lack of GVHD reactivity. They are expanded in vitro after stimulation of PBMC with OKT3, IFN-γ and rhIL-2. This phase I study was designed to test the safety and feasibility of repeated infusions of in vitro expanded donor derived CIK cells given to patients relapsed after allogeneic HSCT. The mean number of starting total nucleated cells was 707 × 10⁶ (range 58–1500 × 10⁶). After a median 22 days of culture, a mean percentage of 51% CD3⁺CD56⁺ cells (range 40–71%) was obtained corresponding to an absolute mean number of 1421×10⁶ total CIK cells (range 422–2470 × 10⁶). Eleven patients with AML (n=4), HD (n=3), CMML (n=1), pre-B ALL (n=1) and MDS (n=2), all relapsed after sibling (6) or matched unrelated donor (5) HSCT, entered this study. Before CIK administration, 7 patients had received one or more additional salvage treatments including chemotherapy (5), radiotherapy (1) and unmanipulated DLI (6) without any significant tumor response. The median number of CIK infusions was 2 (range 1–7) and the median number of total CIK cells was 14.5 ×10⁶/kg (7.2–51). The infusions were well tolerated and no acute or late infusion-related reactions were registered. Acute GVHD (grade I and II) was observed in 4 patients 30 days after the last CIK infusion, which progressed into extensive chronic GVHD in 2 cases. In 6 patients, no significant clinical response could be registered so that disease progression and death occurred rapidly. In contrast, 5 patients achieved measurable responses: a patient with MDS, who had been treated with CIK cells alone, showed a hematologic improvement but subsequently progressed and died. One patient with HD received local radiotherapy and 7 CIK infusions (total of 51×10⁶/kg CIK cells) which allowed the achievement of a good PR. After almost 1 year (300 days), he progressed and chemotherapy was given with achievement of a very good PR. A second patient with HD received one DLI at day 516 and 1 CIK infusion (12.2×10⁶/kg) at day 537. At day 572, chemotherapy was initiated due to the persistence of disease. At the end of chemotherapy he received 3 additional CIK infusions for a total of 34×10⁶/kg from days 711–752, without signs of aGVHD and is presently in CR at more than 780 days. One patient with CMML had been treated with DLI on day 102 and with a total of 38×10⁶/kg CIK cells, given in four infusions from days 137–530, because of the appearance of mixed chimerism. Full chimerism was achieved 42 days after the first CIK infusion. The patient remains in CR at day 576. A second MDS patient, who had not achieved any significant response after five DLI (days 411–559), obtained a complete hematologic, cytogenetic and molecular remission after a single CIK infusion (7.6 ×10⁶/kg) given at day 603 and remains in CR at day 680. This study shows that the production of allogeneic CIK cells is feasible, their infusion is generally safe and may induce clinical remission in patients relapsing after HSCT.