A Phase II Study of Sequential Administration of DLI and Cytokine Induced Killer (CIK) Cells in Patients with Hematologic Malignancies Relapsing After Allogeneic Hematopoietic Stem Cell Transplantation: Preliminary Results

Cytokine Induced Killer (CIK) cells have been previously shown by us and others to possess non restricted, NK-like anti-tumoral cytotoxicity in vitro and in vivo, with little graft-versus host disease (GVHD), in vitro and in several animal models. We have previously performed a phase I study with donor derived CIK cells in 11 adult hematologic patients and shown that the infusions of CIK cells (median 12.4 × 10⁶/kg, range 7.2 to 87.4) were well tolerated and no acute or late infusion related reactions were recorded. Acute GVHD (grade I and II) was observed in 4 patients and progressed into extensive chronic GVHD in two cases (Introna et al, Haematologica 92:952, 2007).

This study is an open-labeled, multicenter, exploratory phase IIA study to evaluate the safety (dose-finding) and efficacy of a sequential administration of donor derived unmanipulated lymphocytes (DLI) plus in vitro expanded CIK cells to patients with hematologic malignancies relapsing after related or unrelated allogeneic hematopoietic stem cells transplantation. The protocol was formally approved by the italian competent national authority (Agenzia Italiana del Farmaco, AIFA) on 14/04/2009. Two infusions of unmanipulated DLI (1×10⁶/kg each) were given with a minimum interval of 3 weeks. Three infusions of donor CIK cells were then administered according to a dose escalating program, starting 3 weeks after the second DLI. CIK administrations were separated by 3 weeks intervals. Up to 4 combinations of dose escalating levels were provided in sequential order until the maximal tolerated dose (MTD) was reached. Indeed the first triplet of patients was supposed to receive CIK cells at the doses of 1×10⁶/kg, 1×10⁶/kg and 5×10⁶/kg, the second 1×10⁶/kg, 5×10⁶/kg, 5×10⁶/kg, the third 1×10⁶/kg, 5×10⁶/kg,10×10⁶/kg, the last triplet 5×10⁶/kg, 5×10⁶/kg, 10×10⁶/kg. In case of grade II or more severe acute GVHD, the next scheduled infusion was planned to be suspended. Only grade IV acute GVHD was considered the dose limiting toxicity (DLT). Once identified the MTD, this same dose will be administered up to 24 patients in a two-stage Simon's design.

So far 16 patients have been enrolled and 12 are evaluable. No DLT (grade IV acute GVHD) was observed at any dose. One patient suffered from grade III skin and gut acute GVHD in the group which received the highest dose and the therapy was stopped after the first administration of CIK cells (5×10⁶/kg), while another patient showed grade I skin acute GVHD in this same group, but completed the 3 administrations program. So far, 7 patients have received the highest dose of CIK cells and they all completed the schedule without toxicity except one case. As per protocol, the best clinical response was evaluated 100 days after the end of the last CIK administration. We observed 3 CR (3 AML), 5 PR (3 AML, 1 MM and 1 HD) and 4 NR (2 AML, 1 NHL and 1 MM) in the 12 evaluable patients. Of the 12 evaluable patients, 5 required additional therapy at the end of the cell therapy program because of NR (3 patients) or to improve the PR (2 patients). Four patients died after a mean 63 days (3 due to relapse and 1 for infection), 6 patients are in PR and 2 patients remain in CR.

These preliminary observations suggest that the sequential infusion of DLI and CIK cells is feasible with relatively minor toxicity, the MTD has not been achieved and the triplet of three CIK administrations of 5×10⁶/kg, 5×10⁶/kg and 10×10⁶/kg will be further evaluated in 17 additional patients. This cell therapy program confirms the antineoplastic activity of this cell therapy schedule in some patients relapsing after allogeneic stem cell transplantation.

No relevant conflicts of interest to declare.