Sandrine Meyer-Monard

Purified donor NK-lymphocyte infusion to consolidate engraftment after haploidentical stem cell transplantation.

This pilot study tested feasibility of natural killer cell purification and infusion (NK-DLI) in patients after haploidentical hematopoietic stem cell transplantation (HSCT). The aim was to obtain ⩾1.0 × 107/kg CD56+/CD3− NK cells and <1.0 × 105/kg CD3+ T cells. Mononuclear cells were collected by 10 l leukapheresis. A two-step ex vivo procedure was used to purify NK cells, using an immunomagnetic T-cell depletion, followed by NK-cell enrichment. Five patients with high-risk myeloid malignancies were included, presenting 3–12 months after a haploidentical HSCT with mixed chimerism (3), impending graft failure (1) or early relapse (1). The purified product contained a median of 1.61 × 107/kg (range 0.21–2.2) NK cells and 0.29 × 105/kg (0.11–1.1) T cells. A purity of NK cells of 97% (78–99), a recovery of 35.5% (13–75), and a T-cell depletion of 3.55 log (2.9–4.5) was achieved. Infusions were well tolerated and none of the patients developed graft-versus-host disease. We observed an increase in donor chimerism in 2/5, stable mixed chimerism, decreasing chimerism and relapse of AML in one patient each. Selection of NK-DLI is technically feasible. NK cells are well tolerated when used as adoptive immunotherapy in recipients of haploidentical HSCT.

Very long-term outcome of acute promyelocytic leukemia after treatment with all-trans retinoic acid and chemotherapy: the European APL Group experience

Acute promyelocytic leukemia (APL) is highly curable with the combination of all-trans retinoic acid (ATRA) and anthracycline-based chemotherapy (CT), but very long-term results of this treatment, when CT should be added to ATRA and the role of maintenance treatment, remain uncertain. In our APL93 trial that included 576 newly diagnosed APL patients, with a median follow-up of 10 years, 10-year survival was 77%. Maintenance treatment significantly reduced 10-year cumulative incidence of relapses, from 43.2% to 33%, 23.4%, and 13.4% with no maintenance, maintenance using intermittent ATRA, continuous 6 mercaptopurine plus methotrexate, and both treatments, respectively (P < .001). Maintenance particularly benefited patients with white blood cell (WBC) count higher than 5 x 10(9)/L (5000/microL). Early addition of CT to ATRA significantly improved 10-year event-free survival (EFS), but without significant effect on overall survival (OS). The 10-year cumulative incidence of deaths in complete response (CR), resulting mainly from myelosuppression, was 5.7%, 15.4%, and 21.7% in patients younger than 55, 55 to 65, and older than 65 years, respectively, supporting the need for less myelosuppressive treatments, particularly for consolidation therapy. This study is registered at http://clinicaltrials.gov as NCT00599937.

Is Cytarabine Useful in the Treatment of Acute Promyelocytic Leukemia? Results of a Randomized Trial From the European Acute Promyelocytic Leukemia Group

PURPOSE Several phase II studies have suggested that cytarabine (AraC) was not required in the treatment of newly diagnosed acute promyelocytic leukemia (APL) patients receiving all-trans-retinoic acid (ATRA), an anthracycline, and maintenance therapy, and we aimed at confirming this finding in a randomized trial. PATIENTS AND METHODS Newly diagnosed APL patients younger than age 60 years with a WBC count of less than 10,000/microL were randomly assigned to receive either ATRA combined with and followed by three daunorubicin (DNR) plus AraC courses and a 2-year maintenance regimen (AraC group) or the same treatment but without AraC (no AraC group). Patients older than age 60 years and patients with initial WBC count of more than 10,000/microL were not randomly assigned but received risk-adapted treatment, with higher dose of AraC and CNS prophylaxis in patients with WBC counts more than 10,000/microL. RESULTS Overall, 328 (96.5%) of 340 patients achieved complete remission (CR). In the AraC and the no AraC groups, the CR rates were 99% and 94% (P = .12), the 2-year cumulative incidence of relapse (CIR) rates were 4.7% and 15.9% (P = .011), the event-free survival (EFS) rates were 93.3% and 77.2% (P = .0021), and survival rates were 97.9% and 89.6% (P = .0066), respectively. In patients younger than age 60 years with WBC counts more than 10,000/microL, the CR, 2-year CIR, EFS, and survival rates were 97.3%, 2.9%, 89%, and 91.9%, respectively. CONCLUSION These results support a role for AraC in addition to ATRA and anthracyclines in the treatment of newly diagnosed APL, at least using DNR at the cumulative dose we used and with the consolidation and maintenance regimens we used.

Prognostic implication of FLT3 and Ras gene mutations in patients with acute promyelocytic leukemia (APL): a retrospective study from the European APL Group

Internal tandem duplications (ITDs) of the FLT3 gene have been observed in about 35% of APL cases. If FLT3-ITD is associated with a worse outcome in patients with acute myeloid leukemia (AML) in general, its prognostic value in acute promyelocytic leukemia (APL) is still a matter of debate. We investigated incidence, associated clinical features, and prognostic implication of FLT3-ITD, but also FLT3-D835 point mutation and N-Ras or K-Ras mutations in 119 APL patients, all prospectively enrolled in the two consecutive APL-93 and APL-2000 trials. Mutation incidences were 38, 20, and 4%, for FLT3-ITD, FLT3-D835, and Ras, respectively. The presence of FLT3-ITD was associated with high white blood cell count, high Sanz index, M3-variant subtype, and V/S PML-RARα isoforms. Complete remission (CR), induction death, and death in CR rates were not affected by FLT3 or Ras mutations, as well as cumulative incidence of relapse. However, a trend for a shorter overall survival (P=0.09) was observed in FLT3-ITD patients, because of a very poor postrelapse survival (P=0.02). This feature, which has been also reported in patients with AML in general, is suggestive of an underlying genetic instability in FLT3-ITD patients, leading to the acquisition of additional unknown bad-prognosis gene mutations at relapse.

Pre-emptive immunotherapy with purified natural killer cells after haploidentical SCT: a prospective phase II study in two centers

Adoptive immunotherapy with allogeneic purified natural killer (NK) cell products might exert graft-versus-tumor alloreactivity with little risk of GVHD. In a prospective phase II study in two centers, we administered purified NK cell products to high-risk patients treated with haploidentical T-cell-depleted SCT. Sixteen patients received a total of 29 NK cell infusions on days +3, +40 and +100 after transplantation. Median doses (and ranges) of infused NK- and T-cells per product were 1.21 (0.3–3.8) × 107/kg and 0.03 (0.004–0.72) × 105/kg, respectively. With a median follow-up of 5.8 years 4/16 patients are alive. Cause of death was relapse in five, GVHD in three, graft failure in three, and transplant related neurotoxicity in one patient. Four patients developed acute GVHD⩾grade II, all receiving a total of ⩾0.5 × 105 T cells/kg. Compared with historical controls, NK cell infusions had no apparent effect on the rates of graft failure or relapse. Adoptive transfer of allogeneic NK cells is safe and feasible, but further studies are needed to determine the optimal dose and timing of NK cell therapy. Moreover, NK cell activation/expansion may be required to attain clinical benefit, while careful consideration must be given to the number of T cells infused.

Improved Outcome of Acute Promyelocytic Leukemia With High WBC Counts Over the Last 15 Years: The European APL Group Experience

PURPOSE Acute promyelocytic leukemia (APL) with pretreatment WBC counts greater than 10,000/microL is still considered to carry a poorer prognosis than APL with WBC lower than 10,000/mL. We evaluated outcome improvement in such patients in recent years. PATIENTS AND METHODS Nine hundred two patients with APL, including 204 patients and 68 patients with WBC counts more than 10,000/microL and more than 50,000/microL, respectively, were enrolled between 1993 and 2005 in two successive randomized trials of the European APL group (APL 93 and APL 2000) that tested, in particular, the modalities of combination of all-trans retinoic acid (ATRA) and chemotherapy, maintenance treatment, escalating doses of cytarabine, early administration of dexamethasone, and CNS prophylaxis. RESULTS Between the APL 93 and 2000 trials, the complete response (CR) rate increased from 89.6% to 93%, and the 5-year cumulative incidence of relapse (CIR) decreased from 40% to 9.5% in patients with WBC counts of 10,000 to 50,000/microL. In patients with WBC counts more than 50,000/microL, the CR rate increased from 82% to 91%, and 5-year CIR decreased from 59% to 24%. Whereas in the APL 93 trial, increased WBC counts were significantly associated with higher CIR and shorter survival, this was not the case in the APL 2000 trial. In patients with increased WBC counts, enrollment onto the APL 2000 trial (v APL 93) and combined maintenance with ATRA and chemotherapy were associated with significantly lower CIR and better survival. CONCLUSION Outcome of APL with high WBC count has markedly improved over the years as a result of fewer early deaths and fewer relapses. Better initial supportive care and combined maintenance treatment have contributed to this improvement.

Activated natural killer cells from patients with acute myeloid leukemia are cytotoxic against autologous leukemic blasts in NOD/SCID mice.

Natural killer (NK) cells are implicated in the surveillance of hematological malignancies. They participate in the immune response against residual acute myeloid leukemia (AML) after hematopoietic stem cell transplantation with partial HLA class I disparity. However, the role of NK cells in autologous leukemia-specific immunity remains poorly understood. We studied the function of NK cells in AML patients at diagnosis. Following isolation, CD56+CD3− cells exhibited a high proliferative potential in vitro in response to interleukin (IL)-2. The polyclonal population of activated AML-NK cells expressed normal levels of the activating receptor NKG2D and the major natural cytotoxicity receptor NKp46. AML-NK cells were highly effective with respect to interferon-γ production, cytotoxicity against HLA class I-deficient K562 erythroleukemia cells in vitro and retardation of tumor growth in vivo in K562-bearing NOD/SCID mice. Importantly, when AML blasts were injected into NOD/SCID mice, a single dose of adoptively transfered autologous AML-NK cells significantly reduced the AML load by 8–77%. Recognition of AML blasts may be related to the observed upregulation of ligands for NKG2D and natural cytotoxicity receptors in vivo. We conclude that AML patient-derived NK cells are fully functional, in support of exploring the benefit of AML immunotherapy with IL-2-stimulated autologous NK cells.

Clinical Grade Purification and Expansion of NK Cell Products for an Optimized Manufacturing Protocol

Allogeneic natural killer (NK) cells are used for adoptive immunotherapy after stem cell transplantation. In order to overcome technical limitations in NK cell purification and activation, the following study investigates the impact of different variables on NK cell recovery, cytotoxicity, and T-cell depletion during good manufacturing practice (GMP)-grade NK cell selection. Forty NK cell products were derived from 54 unstimulated donor leukaphereses using immunomagnetic CD3 T-cell depletion, followed by a CD56 cell enrichment step. For T-cell depletion, either the depletion 2.1 program in single or double procedure (D2.11depl, n = 18; D2.12depl, n = 13) or the faster depletion 3.1 (D3.1, n = 9) was used on the CliniMACS instrument. Seventeen purified NK cell products were activated in vitro by IL-2 for 12 days. The whole process resulted in a median number of 7.59 × 108 CD56+CD3− cells with both purity and viability of 94%, respectively. The T-cell depletion was significantly better using D2.11depl/2depl compared to D3.1 (log 4.6/log 4.9 vs. log 3.7; p < 0.01) and double procedure in two stages led always to residual T cells below 0.1%. In contrast D3.1 was superior to D2.11depl/2depl with regard to recovery of CD56+CD3− NK cells (68% vs. 41%/38%). Concomitant monocytes and especially IL-2 activation led to increased NK cell activity against malignant target cells compared to unstimulated NK cells, which correlated with both up-regulation of natural cytotoxicity receptors and intracellular signaling. Overall, wide variations in the NK cell expansion rate and the distribution of NK cell subpopulations were found. In conclusion, our results indicate that GMP-grade purification of NK cells might be improved by a sequential processing of T-cell depletion program D2.1 and D3.1. In addition NK cell expansion protocols need to be further optimized.

Good manufacturing practice-compliant cell sorting and large-scale expansion of single KIR-positive alloreactive human natural killer cells for multiple infusions to leukemia patients.

BACKGROUND AIMS Alloreactive natural killer (NK) cells are potent effectors of innate anti-tumor defense. The introduction of NK cell-based immunotherapy to current treatment options in acute myeloid leukemia (AML) requires NK cell products with high anti-leukemic efficacy optimized for clinical use. METHODS We describe a good manufacturing practice (GMP)-compliant protocol of large-scale ex vivo expansion of alloreactive NK cells suitable for multiple donor lymphocyte infusions (NK-DLI) in AML. CliniMACS-purified NK cells were cultured in closed air-permeable culture bags with certified culture medium and components approved for human use [human serum, interleukin (IL)-2, IL-15 and anti-CD3 antibody] and with autologous irradiated feeder cells. RESULTS NK cells (6.0 ± 1.2 x 10(8)) were purified from leukaphereses (8.1 ± 0.8 L) of six healthy donors and cultured under GMP conditions. NK cell numbers increased 117.0 ± 20.0-fold in 19 days. To reduce the culture volume associated with expansion of bulk NK cells and to expand selectively the alloreactive NK cell subsets, GMP-certified cell sorting was introduced to obtain cells with single killer immunoglobulin-like receptor (KIR) specificities. The subsequent GMP-compliant expansion of single KIR+ cells was 268.3 ± 66.8-fold, with a contaminating T-cell content of only 0.006 ± 0.002%. The single KIR-expressing NK cells were cytotoxic against HLA-mismatched primary AML blasts in vitro and effectively reduced tumor cell load in vivo in NOD/SCID mice transplanted with human AML. CONCLUSIONS The approach to generating large numbers of GMP-grade alloreactive NK cells described here provides the basis for clinical efficacy trials of NK-DLI to complement and advance therapeutic strategies against human AML.

Clinical‐grade purification of natural killer cells in haploidentical hematopoietic stem cell transplantation

BACKGROUND: Because of a high risk of graft‐versus‐host disease (GVHD), donor lymphocyte infusions with unmodified lymphapheresis products are not used after haploidentical hematopoietic stem cell transplantation. Natural killer (NK) cells have antitumor activity and may consolidate engraftment without inducing GVHD. Production of NK cells under good manufacturing practice (GMP) conditions in a sufficient number is difficult.