Disease relapse is a major cause of mortality following allogeneic hematopoietic stem cell transplantation (HSCT) for hematologic malignancies. When allogeneic transplant fails the most common therapeutic strategy is to increase the anti-tumor activity of donor immune system through infusion of donor lymphocytes (DLI). Use of DLI can effectively treat limited relapses, but can induce graft-versus-host disease (GvHD) in the range of 40-60% of the patients. With the advances in HSCT procedure, the use of HLA-mismatched (haplo) family donors became feasible and extended the opportunity for HSCT to almost all patients lacking an HLA-matched donor. Due to the promising results of the procedure and the easier access to the donor, the number of haplo-HSCT transplant is steeply increasing. However, strategies aiming at eliciting the immune control of the relapse after haplo-HSCT are hampered by absence of prospective data that guide treatment and the fear of inducing GvHD in this setting of profound HLA disparity between donor and recipient.

* Despite the use of DLI in haplo-HSCT is not a standard practice, DLI are occasionally empirically used, mainly due to the lack of alternative treatment.
* Cytokine Induced Killer (CIK) cells are T lymphocytes expressing the CD56 marker, i.e. CIK are CD3/CD56 double positive cells. CIK cells are produced in vitro by incubating blood leukocytes according to a specific expansion protocol which includes initial stimulation with Interferon-gamma and anti-CD3 antibody, followed by expansion with (Interleukin-2) IL-2. CIK cells are non MHC restricted, cytotoxic, anti-tumoral cells which share characteristics of both T and NK cells and show in vivo a very strong cytolytic activity against leukemia, graft versus leukemia, while being essentially devoid of graft versus host reactivity. They show a natural non-MHC restricted (T Cell Receptor)TCR independent cytotoxicity against malignant targets cells, involving perforin and granzyme release and NKG2D, as well as CD56 and other small target molecules. In the past 15 years the investigators have extensively studied the use of cytokine-induced killer (CIK) cells as alternative cellular therapy to treat disease relapse after HSCT. The key feature of CIK cell therapy in the context of haplo- HSCT is the lower risk of inducing GvHD compared to DLI, that could permit to avoid the devastating effect of acute and chronic GvHD in terms of decreased survival, quality of life, disability and need of additional care. Indeed, beyond the dramatic impact in the quality and quantity of life of patients, costs for the health system of the management of acute and chronic GvHD are exceedingly high. At this regard, CIK cells have been regarded as the cellular therapy that is associated with a more favourable therapeutic index compared to DLI.
* In an early Phase I study the investigators observed remissions in 3 of 11 patients who were treated with infusion of CIK cells at a time when malignant cells were detectable. In each of these 3 cases, the patient had been previously treated unsuccessfully with conventional DLI. Successful remission induction by infusion of CIK cells after unsuccessful DLI suggests that the (Graft Versus Leukemia) GVL activity of CIK cells was attributable to NK-T cells. In a subsequent phase I clinical trial was assessed the feasibility of using CIK cells from HLA-matched sibling donors. Using a dose escalation design, the investigators showed that CIK cells could be given at doses as high as 1x10\^8 per kg recipient body weight without causing acute infusion-related toxicity. The investigators recently reported the final results of a phase II multicenter pilot study, showing that CIK cell treatment for the relapse after HSCT is effective with a low toxicity in terms of GvHD compared to DLI. Importantly for the present proposal, in this study, 5 patients were treated in the context of haplo- HSCT. These did not show any different response or safety concern compared to other patients, suggesting the feasibility of this approach in a haploidentical context. Similarly, another study of CIK cellular therapy in HSCT including also patients with haploidentical donors confirmed the feasibility and safety of this approach. Considering that infused T cells are associated with risk of GvHD induction, especially in the haploidentical transplantation setting, novel cellular therapies manipulated to minimize GvHD while enhancing the graft-versus leukemia efficacy need to be tested in early phase clinical trials. Thus, the aim of the present proposal is to use CIK cells as a platform for a safe and effective cellular therapy in the context of haploidentical transplantation. As no dose limiting toxicity has been reached in phase I/II studies and no clear relationship among dose and both toxicity and response emerged so far, in the present study the investigators planned to use the final standard dose of our previous phase II study of 5x106 cells/kg, 5x10\^6 and 10x10\^6 cells/kg with no schedule modification . Three infusion of CIK cells will be administered every 3 weeks.