Durable engraftment after pharmacological pre-transplant immune suppression followed by reduced-toxicity myeloablative haploidentical stem cell transplantation in highly HLA-immunized adults with sickle cell disease.

Allogeneic stem cell transplantation (Allo-SCT) is the only rapidly available curative treatment modality in patients with severe sickle cell disease (SCD). The development of reduced-toxicity myeloablative conditioning (RT-MAC) regimen and the use of partially matched family donors with post-transplantation cyclophosphamide (PT-Cy) have widened the access to Allo-SCT. Antibodies against donor-specific HLA (DSA) increase the risk of engraftment failure in HLA mismatched Allo-SCT. We report the results of five patients with SCD, whereas three with DSA, who underwent an unmanipulated haploidentical stem cell transplantation (Haplo-SCT) after a busulfan-based RT-MAC regimen with PT-Cy. To reduce the risk of engraftment failure, a sequential two courses pharmacological pre-transplant immune suppression (PTIS) phase was added prior to the conditioning regimen. All patients engrafted successfully. The procedure was well tolerated. None of the patients developed acute GVHD, whereas one developed moderate chronic GVHD. After a median follow-up of 5 years (range, 2.2-9), all patients are free of pain with excellent quality of life. Our report shows that Haplo-SCT after a RT-MAC regimen is feasible and safe with stable long-term engraftment and excellent disease control. The risk of graft failure can be abrogated by adding a PTIS phase prior to initiating the conditioning regimen.

Peripheral blood haploidentical hematopoietic cell transplantation for patients aged 70 years and over with acute myeloid leukemia or high-risk myelodysplastic syndrome.

Haploidentical stem cell transplantation (Haplo-SCT) using non-myeloablative conditioning regimen (NMAC) has extended the feasibility of allogeneic transplantation, notably in older patients. However, there is few data specifically focusing on patients aged 70 years and over with AML and MDS. Thus the benefit of transplantation in this population is still debated. Here we report our single center experience of peripheral blood Haplo-SCT with NMAC and post-transplantation cyclophosphamide in AML and MDS patients aged 70 years and over. We analyzed 50 patients (27 AML, 23 MDS) with a median age of 72 years (70-77), 12/50 (24%) with active disease at Haplo-SCT. Cumulative incidence of grade 3-4 acute and moderate or severe chronic GVHD were 6% and 25%, respectively. Non-relapse mortality (NRM) at day +100 was 0%. NRM, relapse, PFS and OS at 3 years were 16%, 18%, 66%, and 69%, respectively. Among patients who were disease free at 2 years post Haplo-SCT, 88% are living without immunosuppressive treatment. Peripheral blood Haplo-SCT is feasible in selected AML/MDS patients over 70 years, without any early NRM. It produces long-term disease control and survival. Thus, age by itself should not be considered as a formal barrier to Haplo-SCT.

Endowing universal CAR T-cell with immune-evasive properties using TALEN-gene editing.

Universal CAR T-cell therapies are poised to revolutionize cancer treatment and to improve patient outcomes. However, realizing these advantages in an allogeneic setting requires universal CAR T-cells that can kill target tumor cells, avoid depletion by the host immune system, and proliferate without attacking host tissues. Here, we describe the development of a novel immune-evasive universal CAR T-cells scaffold using precise TALEN-mediated gene editing and DNA matrices vectorized by recombinant adeno-associated virus 6. We simultaneously disrupt and repurpose the endogenous TRAC and B2M loci to generate TCRαß- and HLA-ABC-deficient T-cells expressing the CAR construct and the NK-inhibitor named HLA-E. This highly efficient gene editing process enables the engineered T-cells to evade NK cell and alloresponsive T-cell attacks and extend their persistence and antitumor activity in the presence of cytotoxic levels of NK cell in vivo and in vitro, respectively. This scaffold could enable the broad use of universal CAR T-cells in allogeneic settings and holds great promise for clinical applications.

High-dimensional mass cytometry analysis of NK cell alterations in AML identifies a subgroup with adverse clinical outcome.

Natural killer (NK) cells are major antileukemic immune effectors. Leukemic blasts have a negative impact on NK cell function and promote the emergence of phenotypically and functionally impaired NK cells. In the current work, we highlight an accumulation of CD56-CD16+ unconventional NK cells in acute myeloid leukemia (AML), an aberrant subset initially described as being elevated in patients chronically infected with HIV-1. Deep phenotyping of NK cells was performed using peripheral blood from patients with newly diagnosed AML (n = 48, HEMATOBIO cohort, NCT02320656) and healthy subjects (n = 18) by mass cytometry. We showed evidence of a moderate to drastic accumulation of CD56-CD16+ unconventional NK cells in 27% of patients. These NK cells displayed decreased expression of NKG2A as well as the triggering receptors NKp30 and NKp46, in line with previous observations in HIV-infected patients. High-dimensional characterization of these NK cells highlighted a decreased expression of three additional major triggering receptors required for NK cell activation, NKG2D, DNAM-1, and CD96. A high proportion of CD56-CD16+ NK cells at diagnosis was associated with an adverse clinical outcome and decreased overall survival (HR = 0.13; P = 0.0002) and event-free survival (HR = 0.33; P = 0.018) and retained statistical significance in multivariate analysis. Pseudotime analysis of the NK cell compartment highlighted a disruption of the maturation process, with a bifurcation from conventional NK cells toward CD56-CD16+ NK cells. Overall, our data suggest that the accumulation of CD56-CD16+ NK cells may be the consequence of immune escape from innate immunity during AML progression.

Mechanisms of NK cell dysfunction in the tumor microenvironment and current clinical approaches to harness NK cell potential for immunotherapy.

NK cells are innate immune cells with inherent capabilities in both recognizing and killing cancer cells. NK cell phenotypes and functional alterations are being described with increasing precision among patients harboring various cancer types, emphasizing the critical role that NK cells play in antitumor immune responses. In addition, advances in understanding NK cell biology have improved our knowledge of such alterations, thereby expanding the potential exploitation of NK cells' anticancer capabilities. In this review, we present an overview of (1) the various types of NK cell alterations that may contribute to immune evasion in cancer patients and (2) the various strategies to improve NK cell-based anticancer immunotherapies, including pharmacologic modulation and/or genetic modification.

Allogeneic stem cell transplantation in poor prognosis peripheral T-cell lymphoma: the impact of different donor type on outcome.

We report the outcome of 68 patients with advanced peripheral T-cell lymphoma receiving transplantation from haploidentical or from conventional donors. The 4-year OS, PFS, 2-year cumulative incidence of relapse and 2-year GRFS was 75%, 70%, 21%, and 51%, respectively. Survival was not affected by donor type. The 2-year NRM was 9%, lower after related or haploidentical donor (21% vs 0% vs 7%; p = 0.06). Grade 2-4 aGVHD cumulative incidence was significantly different after transplantation from haploidentical vs matched sibling vs unrelated donor, and (24% vs 35% vs 58%, p = 0.024). The familial donor cohort was compared to the unrelated cohort. Familial donor induced less grade 2-4 aGVHD, with a trend to less grade 3-4 aGVHD or moderate-severe cGVHD. The OS and PFS were not different, while the relapse risk and NRM were reduced. Allo-SCT is highly effective in T-cell lymphoma, with low NRM and low relapse rate. The incidence of aGVHD was lower after haploidentical transplantation. Related donor may challenge unrelated transplant reducing the risk of relapse and NRM.

Nonmyeloablative Conditioning Regimen before T Cell Replete Haploidentical Transplantation with Post-Transplant Cyclophosphamide for Advanced Hodgkin and Non-Hodgkin Lymphomas.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a valid option in patients with refractory lymphomas. HLA haploidentical stem cell transplantation (haplo-SCT) expanded the accessibility to allogeneic hematopoietic cell transplantation. The aims of study were to retrospectively assess the toxicity and efficacy of haplo-SCT using nonmyeloablative conditioning in patients with advanced lymphoma. In total, 147 patients with advanced lymphoma at 2 partner institutions were included. Patients received a uniform nonmyeloablative conditioning regimen and graft-versus-host disease (GVHD) prophylaxis. The primary endpoints were progression-free survival (PFS), overall survival (OS), GVHD, nonrelapse mortality, and GVHD, relapse-free survival (GRFS). Median follow-up was 39 months (range, 6 to 114 months). The median age was 46 years (range, 19 to 71 years). Sixty-five percent of patients were in complete remission (CR) at transplantation. Cumulative incidence of grade II to IV acute GVHD was 30% (95% confidence interval [Cl], 23% to 38%). Two-year cumulative incidence of all grades of chronic GVHD was 13% (95% CI, 8% to 20%). Two-year cumulative incidence of disease relapse was 19% (95% CI, 14% to 27%), with a higher incidence in patients not being in CR at allo-HCT (CR versus not CR: 12% versus 33%, P = .006). Two-year PFS, OS, and GRFS were 66% (95% CI, 59-75), 73% (95% CI, 66-81), and 56% (95% CI, 48-65), respectively. Haplo-SCT with post-transplantation cyclophosphamide may be considered a valid option for patients with aggressive lymphoma and deserves further evaluation.

Impact of Adding Antithymocyte Globulin to Posttransplantation Cyclophosphamide in Haploidentical Stem-Cell Transplantation.

BACKGROUND: Graft-versus-host disease (GVHD) is a major cause of mortality after allogeneic stem-cell transplantation. Posttransplantation cyclophosphamide (PT/CY) has become standard prophylaxis of GVHD in T-replete haploidentical transplantation. The question is whether adding antithymocyte globulin (ATG) to PT/CY may further reduce the incidence of GVHD compared to PT/CY only. PATIENTS AND METHODS: We retrospectively studied 268 patients undergoing myeloablative haploidentical transplantation with thiotepa, busulfan, and fludarabine (TBF) conditioning. Sixty-nine patients (26%) received ATG. RESULTS: In the ATG group, 3% died due to GVHD versus 8% in the no ATG group. The 100-day and 1-year nonrelapse mortality (NRM) was 0% and 19%, respectively, in the whole cohort. On univariate analysis, the 1-year NRM was 8% versus 23% in patients receiving ATG and no ATG, respectively (P = .005). The no ATG group had a higher incidence of acute GVHD at 12 months compared to the ATG group (22% vs. 12%, respectively, P = .029). The ATG group had better overall survival at 12 months compared to the no ATG group (79% vs. 69%, P = .029). On multivariate analysis, adding ATG to PT/CY had no significant impact on any of the outcomes. A low disease risk index was associated with better overall survival and lower NRM, while Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) score ≥ 3 was associated with higher NRM. CONCLUSION: ATG can be safely used as part of the pretransplantation conditioning and does not increase the incidence of relapse or complications after transplantation.

Checkpoint inhibition before haploidentical transplantation with posttransplant cyclophosphamide in Hodgkin lymphoma.

We report on 59 Hodgkin lymphoma patients undergoing haploidentical stem cell transplantation (SCT; haplo-SCT) with posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis, comparing outcomes based on pretransplant exposure to checkpoint inhibitors (CPIs). Considering pretransplant characteristics, the 2 cohorts (CPI = 29 patients vs no-CPI = 30 patients) were similar, except for the number of prior lines of therapy (6 vs 4; P < .001). With a median follow-up of 26 months (range, 7.5-55 months), by univariate analysis, the 100-day cumulative incidence of grade 2-4 acute GVHD was 41% in the CPI group vs 33% in the no-CPI group (P = .456), whereas the 1-year cumulative incidence of moderate to severe chronic GVHD was 7% vs 8%, respectively (P = .673). In the CPI cohort, the 2-year cumulative incidence of relapse appeared lower compared with the no-CPI cohort (0 vs 20%; P = .054). No differences were observed in terms of overall survival (OS), progression-free survival (PFS), and nonrelapse mortality (NRM) (at 2 years, 77% vs 71% [P = .599], 78% vs 53% [P = .066], and 15% vs 21% [P = .578], respectively). By multivariable analysis, CPI before SCT was an independent protective factor for PFS (hazard ratio [HR], 0.32; P = .037). Stable disease (SD)/progressive disease (PD) was an independent negative prognostic factor for both OS and PFS (HR, 14.3; P < .001 and HR, 14.1; P < .001, respectively) . In conclusion, CPI as a bridge to haplo-SCT seems to improve PFS, with no impact on toxicity profile.

Posttransplantation cyclophosphamide vs. antithymocyte globulin as GVHD prophylaxis for mismatched unrelated hematopoietic stem cell transplantation.

Posttransplant cyclophosphamide (PT-Cy) is an efficient GVHD prophylaxis but has not been extensively evaluated in mismatched unrelated donor (MMUD) allo-HSCT, for which antithymocyte globulin (ATG) is still considered as a standard. Thus, we evaluated the outcome of MMUD allo-HSCT with PT-Cy (n = 22) and performed a historical comparison with a control group receiving ATG (n = 40) in a single center experience. Compared with the ATG group, the risk of grade 2-4 acute GVHD was significantly lower in the PT-Cy group (HR = 0.12, 95% CI = [0.03-0.48], p = 0.002). No difference was observed in the cumulative incidence of chronic GVHD. The risk of both NRM and relapse was significantly lower in the PT-Cy group (NRM: HR = 0.05, 95% CI = [0.00-0.63], p = 0.021; relapse: HR = 0.31; 95% CI = [0.09-1.10], p = 0.07). Thus, we observed significantly better PFS (HR = 0.22, 95% CI = (0.07-0.65); p = 0.006), OS (HR = 0.24, 95% CI = (0.07-0.84); p = 0.026), and GRFS (HR = 0.37, 95% CI = (0.17-0.80); p = 0.011) in the PT-Cy group. We conclude that PT-Cy is an effective GVHD prophylaxis in the setting of MMUD allo-HSCT, resulting in a better outcome compared with standard prophylaxis using ATG. This suggests that as it was shown in the setting of haploidentical allo-HSCT, the use of PT-Cy can overcome the impact of HLA disparity, leading to promising survivals that approach those observed after HLA matched allo-HSCT.

Thiotepa, Fludarabine, and Busulfan Conditioning Regimen before T Cell-Replete Haploidentical Transplantation with Post-Transplant Cyclophosphamide for Acute Myeloid Leukemia: A Bicentric Experience of 100 Patients.

Haploidentical stem cell transplantation (haplo-SCT) with post-transplant cyclophosphamide (PT-Cy) is an alternative treatment for acute myeloid leukemia (AML) patients who lack HLA-matched donors. Relapse after haplo-SCT remains a major concern, especially after nonmyeloablative conditioning regimens. Promising results were reported for TBF-based conditioning regimens (thiotepa, busulfan, and fludarabine) in patients transplanted from different categories of donors and for various disease types but not specifically in PT-Cy haplo-SCT for AML. Here we evaluate the outcome of 100 AML patients who received haplo-SCT with PT-Cy after TBF conditioning regimens (reduced-intensity conditioning, n = 77; myeloablative conditioning, n = 23) in 2 transplant programs. Cumulative incidences of grades III to IV acute and moderate or severe chronic graft-versus-host disease (GVHD) were 7% and 14%, respectively. NRM at 2 years was 28%, significantly influenced by disease status at haplo-SCT (first complete response [CR1] versus advanced AML: 16% versus 38%, P = .016) but not by conditioning intensity or age. The cumulative incidences of relapse at 2 years were 17% and 24% in CR1 and advanced AML, respectively (not significant). Progression-free survival, overall survival, and GVHD and relapse-free survival at 2 years were 67%, 71%, and 49% in CR1 patients, respectively, whereas comparative values in patients with advanced disease were 37%, 41%, and 32%. Our study suggests that TBF conditioning for PT-Cy haplo-SCT is safe and effective for AML patients in CR1. In patients with more advanced disease, the relatively low incidence of relapse seems counterbalanced by a high nonrelapse mortality, underlining the need for alternative strategies to decrease relapse risk, without increasing the intensity of conditioning regimen.

Peripheral Blood Stem Cells versus Bone Marrow for T Cell-Replete Haploidentical Transplantation with Post-Transplant Cyclophosphamide in Hodgkin Lymphoma.

Haploidentical stem cell transplantation (haplo-SCT) with post-transplant cyclophosphamide (PT-Cy) represents a potential curative strategy for patients with Hodgkin lymphoma (HL) when a matched related or unrelated donor is not available. The role of graft source, either bone marrow (BM) or peripheral blood stem cells (PBSCs), in this setting has not been fully elucidated. We performed a retrospective study on 91 patients with HL to compare the outcome after BM (n = 53) or PBSC (n = 38) transplant. Eighty-nine patients engrafted with no difference between BM and PBSCs in terms of median time for neutrophil (20 versus 20 days, P = .405) and platelet (26 versus 26.5 days, P = .994) engraftment. With a median follow-up of 40.2 months, 100-day cumulative incidences of grades II to IV acute graft-versus host disease (GVHD) and grades II to IV acute GVHD were 24% and 4%, respectively. Graft source was not associated with a different risk of acute GVHD both by univariate and multivariate analyses. Consistently, 1-year cumulative incidence of chronic GVHD was 7% with no differences between the 2 graft types (P = .761). Two-year rates of overall survival (OS), progression-free survival (PFS), nonrelapse mortality, and GVHD/relapse-free survival (GRFS) were 67%, 58%, 20%, and 52%, respectively. By univariate analysis, pretransplant disease status was the main variable affecting all outcomes. By multivariate analysis, PBSCs resulted in a protective factor for OS (hazard ratio [HR], .29; P = .006), PFS (HR, .38; P = .001), and GRFS (HR, .44; P = .020). The other independent variables affecting the final outcome were pretransplant disease status and hematopoietic cell transplant-specific comorbidity index. In conclusion, when planning a haplo-SCT with PT-Cy for patients with poor-risk HL, graft type is an important variable to take into account when selecting the best available donor.

Post-transplantation cyclophosphamide-based haploidentical versus Atg-based unrelated donor allogeneic stem cell transplantation for patients younger than 60 years with hematological malignancies: a single-center experience of 209 patients.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is limited by availability of HLA-matched sibling donors (MSDs). The alternative use of unrelated donors (UDs) is currently challenged by haploidentical-related donors (HRDs). We retrospectively analyzed 209 consecutive patients younger than 60 years undergoing allo-HSCT from UDs (n = 128) or HRDs (n = 81). Cumulative incidences of grade 3-4 acute (17 vs. 2%, p = 0.003) and 2-year moderate and severe chronic (20 vs. 2%, p < 0.001) GVHD were significantly higher with UD. Progression-free survival (PFS) was significantly better with HRD (51 vs. 69%, p = 0.019), without significant difference in the cumulative incidence of relapse (CIR), non-relapse mortality (NRM), and overall survival (OS). Multivariate analyses confirmed the lower risk of acute and chronic GVHD (grade 2-4, HR = 0.43, p = 0.005; grade 3-4, HR = 0.20, p = 0.017; all grades, HR = 0.43, p = 0.012; moderate or severe, HR = 0.12, p = 0.004), better PFS (HR = 0.61, p = 0.046), and GRFS (HR = 0.47, p = 0.001) with HRD. This was confirmed in match-paired analysis. In the absence of MSDs, HRD could be considered as a suitable alternative for patients younger than 60 years.

HLA-Matched Sibling versus Unrelated versus Haploidentical Related Donor Allogeneic Hematopoietic Stem Cell Transplantation for Patients Aged Over 60 Years with Acute Myeloid Leukemia: A Single-Center Donor Comparison.

Haploidentical related donor (HRD) allogeneic hematopoietic stem cell transplantation (allo-HSCT) was developed as a valid option for the treatment of acute myeloid leukemia (AML) in the absence of a matched donor. However, many investigators are reluctant to consider the use of this alternative in elderly patients, anticipating high morbidity. Here, we report a single-center comparison of HRD versus matched sibling donor (MSD) and unrelated donor (UD) allo-HSCT for patients with AML aged ≥60 years. Ninety-four patients (MSD: n = 31; UD: n = 30; HRD: n = 33) were analyzed. The median age was 65 (range, 60 to 73) years. We observed a higher cumulative incidence of grade 3 to 4 acute graft-versus-host disease (GVHD) after UD allo-HSCT (MSD versus UD versus HRD: 3% versus 33% versus 6%, respectively; P = .006). Two-year cumulative incidence of moderate or severe chronic GVHD was 17%, 27%, and 16% in the MSD, UD, and HRD groups, respectively (P = .487). No difference was observed in the 2-year cumulative incidence of relapse or nonrelapse mortality (NRM) (relapse: MSD versus UD versus HRD: 32% versus 25% versus 25%, respectively; P = .411; NRM: MSD versus UD versus HRD: 19% versus 27% versus 24%, respectively; P = .709). At 2 years, progression-free survival, overall survival, and GVHD- and relapse-free survival were 48%, 50%, and 39%, respectively, in the MSD group; 48%, 51%, and 23%, respectively, in the UD group; and 50%, 52%, and 32%, respectively, in the HRD group, without statistically significant differences between the groups. We conclude that HRD allo-HSCT is highly feasible and no less efficient than MSD or UD allo-HSCT in patients with AML aged ≥60 years. Thus, the absence of a HLA-identical donor should not limit the consideration of allo-HSCT for the treatment of AML.

Second tyrosine kinase inhibitor discontinuation attempt in patients with chronic myeloid leukemia.

BACKGROUND: Several studies have demonstrated that approximately one-half of patients with chronic myeloid leukemia (CML) who receive treatment with tyrosine kinase inhibitors (TKIs) and achieve and maintain a deep molecular response (DMR) are able to successfully discontinue therapy. In patients who have a molecular relapse, a DMR is rapidly regained upon treatment re-initiation. METHODS: The authors report the results from RE-STIM, a French observational, multicenter study that evaluated treatment-free remission (TFR) in 70 patients who re-attempted TKI discontinuation after a first unsuccessful attempt. After the second TKI discontinuation attempt, the trigger for treatment re-introduction was the loss of a major molecular response in all patients. RESULTS: The median follow-up was 38.3 months (range, 4.7-117 months), and 45 patients (64.3%) lost a major molecular response after a median time off therapy of 5.3 months (range, 2-42 months). TFR rates at 12, 24, and 36 months were 48% (95% confidence interval [CI], 37.6%-61.5%), 42% (95% CI, 31.5%-55.4%), and 35% (95% CI, 24.4%-49.4%), respectively. No progression toward advanced-phase CML occurred, and no efficacy issue was observed upon TKI re-introduction. In univariate analysis, the speed of molecular relapse after the first TKI discontinuation attempt was the only factor significantly associated with outcome. The TFR rate at 24 months was 72% (95% CI, 48.8%-100%) in patients who remained in DMR within the first 3 months after the first TKI discontinuation and 36% (95% CI, 25.8%-51.3%) for others. CONCLUSIONS: This study is the first to demonstrate that a second TKI discontinuation attempt is safe and that a first failed attempt at discontinuing TKI does not preclude a second successful attempt. Cancer 2017;123:4403-10. © 2017 American Cancer Society.