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Feasibility of IL-15-activated cytokine-induced killer cell infusions after haploidentical stem cell transplantation

Haploidentical hematopoietic SCT is an established treatment for high-risk leukemia in patients lacking a HLA-identical donor, and is also being evaluated for refractory solid tumors. The therapeutic success of any SCT for malignant disease is limited by relapse. Impending relapse can be treated by DLI, but DLI is of limited value when initiated during overt relapse.1 Moreover, the high T-cell doses required for DLI pose a risk of severe GVHD, specifically in the haploidentical setting.

Cytokine-induced killer (CIK) cells represent a heterogeneous population of polyclonal CD3+CD56+ T cells with phenotypic and functional properties of natural killer (NK) cells, which arise from CD3+CD56 CIK cell progenitors. CIK cells mediate both specific MHC-restricted recognition and non-MHC-restricted cytotoxicity against target cells.2, 3, 4, 5, 6 The activating NK cell receptor, NKG2D, has a crucial role in binding and cytolytic activity of CIK cells against tumor cells expressing the corresponding ligands.2, 3 The best characterized ligands for NKG2D are relatively restricted to tumor cells. Because of their selective recognition and killing of target cells, CIK cells display negligible alloreactivity and cause minimal GVHD and, therefore, may represent an ideal treatment option for patients at risk of relapse of hematological or solid malignancies after haploidentical SCT.

Accordingly four patients (aged 2–16 years) with hematological or solid malignancies, who failed conventional DLI or NK cell therapy, and who were at high risk of relapse after haploidentical SCT, received CIK therapy on a compassionate use basis, after written informed consent, and case-by-case evaluation by the regional board (Regierungspräsidium Darmstadt, Germany). Cell doses were escalated by 10-fold up to a maximum dose of 1 × 108 CD3+CD56 cells/kg. The minimum interval between infusions was 3 weeks. AML-patients with overt relapse received cytoreductive chemotherapy before infusion.

For generation of CIK cells, 100–300 ml of whole-blood were taken from the original haploidentical stem cell donors after written informed consent. CIK cell generation described previously7 was performed under good manufacturing practice (GMP)-conditions. After 10 days of culture, cells were characterized by flow cytometry as previously described,7 harvested and infused immediately. After infusion, patients received immune monitoring as previously described.8 Furthermore, a semiquantitative PCR approach, based on the amplification of short-tandem-repeat markers, was used for chimerism analyses.9 Unless otherwise cited, obtained data are expressed as mean ± s.d.

Median-fold cell expansion was 4.7 (range: 3.8–8.0-fold) after 10 days of culture (Figure 1a). Cell products contained CD3+CD56 T cells (66.3±18.7%), CD3+CD56+ NK-like T cells (11.4±13.2%), CD3CD56+NK cells (6.9±6.0%), CD3+CD4+ T helper cells (39.3±20.0%), CD3+CD8+ cytotoxic T cells (41.1±18.6%), CD3+ T-cell receptor (TCR)α/β+ α/β-T cells (72.0±15.3%) and CD3+TCRγ/δ+γ/δ-T cells (4.0±2.9%, Figure 1b).

Figure 1

See figure caption next page.

One, five, seven and nine doses of cells were administered in four patients, for a total of 22 infusions. 1 × 105, 1 × 106, 1 × 107 and 1 × 107 CD3+CD56 cells/kg were administered with the initial dose. Thereafter, cell doses were escalated logarithmically at intervals of at least 3 weeks, to a maximum dose of 1 × 108 CD3+CD56 cells/kg (Table 1).

Table 1 Patient characteristics and treatments

Patients included one AML-patient after matched unrelated donor (MUD) SCT for first relapse, followed by DLIs for impending relapse, and first haploidentical SCT, radio-immunotherapy and NK cell therapy for second relapse, who experienced a third and fourth relapse before a second haploidentical SCT. He was in CR at the time of first CIK cell application, but relapsed later. The second AML-patient received MUD SCT in first CR, followed by chemotherapy and haploidentical SCT for first relapse, and received DLI for impending relapse, followed by CIK cell infusions for overt relapse. Both AML-patients achieved a clinical response within 14 days after infusions of escalating cell doses in terms of improvement of donor chimerism or clearance of leukemic blasts in the peripheral blood (Table 1 and Figures 1c and d).

Two patients with solid malignancies—one with alveolar rhabdomyosarcoma in remission after two haploidentical transplantations and one with advanced-stage Ewing sarcoma despite autologous and haploidentical transplantation—were also treated with haploidentical CIK cells. Although no clear therapeutic benefit was apparent especially in patients with solid malignancies, excellent tolerability during infusion and thereafter underscored the safety and feasibility of haploidentical CIK cell therapy (Table 1).

In summary, CIK cells were generated according to GMP-conditions in the presence of IL-15 to increase cytotoxic potential.7 Most of the expanded cells showed a CD3+CD56T-cell phenotype coexpressing TCRα/β. T cells with this phenotype have been associated with GVHD-induction, especially in the haploidentical transplantation setting. Interestingly, within a 2-to-11-month follow-up of sequential dose escalating infusions, we observed no GVHD. Thus far, CIK cell infusions had only been tested after matched-donor allogeneic transplantation.4, 5, 10 Our data demonstrate a similar safety and feasibility of CIK cell therapy from haploidentical donors.

Regarding the efficacy of CIK cell therapy, the situation is less clear. As often occurs in desperate clinical situations, also in our patients, additional salvage therapies were used concomitantly, and thus the cytotoxicity of CIK cells cannot exclusively account for the therapeutic responses observed. In some instances CIK cells controlled disease, but ultimately all four patients relapsed, and three succumbed to their illness. Also other groups have reported limited efficacy of CIK cell infusions.4, 10 In our patients, CIK cell therapy may not have reached its full potential, as it was initiated during advanced disease.1

In conclusion, these findings demonstrate the safety and feasibility of haploidentical CIK cell infusions, albeit in a small number of heterogeneous, pediatric patients, who in part had also received concomitant antitumor therapy. Those limitations notwithstanding, CIK cells provided palliation, and very likely life extension with an excellent quality of life even in patients with overt relapse.


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We thank the LOEWE Center for Cell and Gene Therapy Frankfurt/Main and the Hessian Ministry of Higher Education, Research and the Arts (HMWK); Funding Reference no.: III L 4–518/17.004 (2010). LOEWE Center for Cell and Gene Therapy Frankfurt/Main and the Hessian Ministry of Higher Education, Research and the Arts (HMWK); Funding Ref. no.: III L 4–518/17.004 (2010) and the Else Kröner-Fresenius-Stiftung (P65/09//A112/09) for the kind support of this work.

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Rettinger, E., Bonig, H., Wehner, S. et al. Feasibility of IL-15-activated cytokine-induced killer cell infusions after haploidentical stem cell transplantation. Bone Marrow Transplant 48, 1141–1143 (2013).

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