Natural Killer-cell Therapy for Acute Myeloid Leukemia

This study investigates an innovative treatment for relapsed or refractory acute myeloid leukemia exploiting administration of ex vivo-generated allogeneic natural killer (NK) cells with preceding non-myeloablative conditioning chemotherapy with or without subsequent in vivo IL-2 cytokine support.

This study investigates an innovative treatment for relapsed or refractory acute myeloid leukemia (AML) exploiting administration of ex vivo-generated allogeneic natural killer (NK) cells with preceding non-myeloablative conditioning chemotherapy with or without subsequent in vivo IL-2 cytokine support.

This is a prospective phase I/IIa study. The first phase is a IL-2 dose-escalating safety study in twelve patients. The second phase of the study is designed as a Simon's optimal two-stage single-arm phase IIa study, comprising seventeen patients. Prior to NK cell infusion, all patients will receive cyclophosphamide and fludarabine (Cy/Flu) based lymphodepleting chemotherapy. On day 0, all patients will receive a fixed dose of 1.0-3.0 x 10\^9 allogeneic umbilical cord blood-derived NK cells (UCB-NK cells). These cells are generated ex vivo from CD34+ hematopoietic progenitor cells obtained from an allogeneic UCB unit.

In phase I of the study patients will receive UCB-NK cells without subcutaneous (SC) IL-2, with lower dose SC IL-2 or with higher dose SC IL-2 (n=3 per treatment group, n=6 in the highest tolerable dose). After establishing the safety of UCB-NK cells combined with SC IL-2, we will continue with phase IIa of the study, with ten patients in the first stage (including the six patients from phase I with comparable IL-2 dose) and if clinical efficacy is achieved an additional seven patients in the second stage.

Eligibility Criteria:
Inclusion Criteria:

* AML patients (de novo and secondary) or patients with MDS excess blasts-2 according to WHO criteria 2016, who have stable disease or non-rapidly progressive disease with or without disease controlling medication who are (at time of inclusion) ineligible for allo-SCT.
* Patients may belong to any of the following categories:

  * Relapsed/refractory disease after treatment with intensive chemotherapy, hypomethylating agents, targeted agents, autologous or allo-SCT (at least 6 months ago) and DLI
  * Newly diagnosed, untreated patients ineligible for allo-SCT

Other inclusion criteria:

* Age ≥ 18 years
* WHO performance 0-2
* Life expectancy of \> 4 months
* Written informed consent
* Hydrea is allowed as pre-treatment to control blast count until day -3
* Other disease controlling medication is allowed until day -7

Exclusion Criteria:

* Progressive disease according to ELN criteria in case of previous therapy
* Patients on immunosuppressive drugs or active GvHD
* Patients with active infections (viral, bacterial or fungal); acute anti-infectious therapy must have been completed within 14 days prior to study treatment
* Severe cardiovascular disease (CTCAE III-IV)
* Severe pulmonary dysfunction (CTCAE III-IV)
* Severe renal dysfunction (CTCAE III-IV)
* Severe hepatic dysfunction (CTCAE III-IV)
* Severe neurological or psychiatric dysfunction (CTCAE III-IV)
* Patients on concurrent chemotherapy or interferon-alpha treatment
* Pregnancy or breastfeeding