A phase I trial of NK-92 cells for refractory hematological malignancies relapsing after autologous hematopoietic cell transplantation shows safety and evidence of efficacy A phase I trial of NK-92 cells for refractory hematological malignancies relapsing after autologous hematopoietic cell transplantation shows safety and evidence of efficacy

Haploidentical hematopoietic stem cell transplantation (haploHSCT) with conditioning regimens using post-transplant cyclophosphamide (PTCy) for peripheral blood stem cell (PBSC) grafts is limited by comparably higher rates of acute and chronic graft-versus-host disease (GVHD). Antithymocyte globulin (ATG) may mitigate this risk. We evaluated haploHSCT after reduced-intensity conditioning (RIC) with ATG, PTCy, and cyclosporine to prevent rejection and GVHD. Fifty adults underwent haploHSCT from August 2016 to February 2018. RIC included fludarabine (30 mg/m2/day on days -5 to -2), busulfan (3.2 mg/m2/day on days -3 and -2), and total body irradiation (200 cGy) on day -1. Unmanipulated PBSCs were infused on day 0. GVHD prophylaxis included ATG (4.5 mg/kg over days -3 to -1), PTCy (50 mg/kg/day on days +3 and +4), and cyclosporine from day +5. Median age was 56 years (range, 22 to 70 years); 25 (73.5%) patients were in first complete remission (CR1), 5 (14.7%) were in second complete remission (CR2), and 8 (23.5%) had active disease. Median time to neutrophil engraftment was 16 days (range, 8 to 43 days). At day +100, the cumulative incidence of acute GVHD of any grade, and grades III to IV was 38.3% and 5.2%, respectively. Mild chronic GVHD was seen in 15.5%. Cytomegalovirus (CMV) reactivation occurred in 37 (74%) cases and CMV disease occurred in 4 (11.5%) cases. Epstein-Barr virus (EBV) reactivation occurred in 21 (61.8%) patients. The incidence of histologically confirmed post-transplantation lymphoproliferative disorder (PTLD) was 5.8%. Four patients received rituximab. There were no CMV, EBV, or PTLD-related deaths. Six-month and 1-year overall survival (OS), cumulative incidence of relapse (CIR), and nonrelapse mortality (NRM) were 73.9%, 10.2%, and 19.4%, respectively, and 48.1%, 16% and 38.2%, respectively. Infection was the most common cause of death (18%). Unmanipulated haploidentical PBSC transplantation following RIC with ATG, PTCy, and cyclosporine as a GVHD prevention strategy results in low rates of acute and chronic GVHD.

In recent decades, therapy for acute myeloid leukemia (AML) has remained relatively unchanged, with chemotherapy regimens primarily consisting of an induction regimen based on a daunorubicin and cytarabine backbone, followed by consolidation chemotherapy. Patients who are relapsed or refractory can be treated with allogeneic hematopoietic stem-cell transplantation with modest benefits to event-free and overall survival. Other modalities of immunotherapy include antibody therapies, which hold considerable promise and can be categorized into unconjugated classical antibodies, multivalent recombinant antibodies (bi-, tri- and quad-specific), toxin-conjugated antibodies and radio-conjugated antibodies. While unconjugated antibodies can facilitate Natural Killer (NK) cell antibody-dependent cell-mediated cytotoxicity (ADCC), bi- and tri-specific antibodies can engage either NK cells or T-cells to redirect cytotoxicity against AML targets in a highly efficient manner, similarly to classic ADCC. Finally, toxin-conjugated and radio-conjugated antibodies can increase the potency of antibody therapies. Several AML tumour-associated antigens are at the forefront of targeted therapy development, which include CD33, CD123, CD13, CLL-1 and CD38 and which may be present on both AML blasts and leukemic stem cells. This review focused on antibody therapies for AML, including pre-clinical studies of these agents and those that are either entering or have been tested in early phase clinical trials. Antibodies for checkpoint inhibition and microenvironment targeting in AML were excluded from this review.

Posttransplant cyclophosphamide (PTCy) is a promising graft-versus-host disease (GVHD) prophylaxis in haploidentical and matched unrelated donor hematopoietic stem cell transplantation (HSCT), but its role in matched sibling donor (MSD) transplants remains unclear. We conducted a retrospective study of 413 MSD-HSCT patients receiving peripheral blood stem cell (PBSC) grafts from January 2010 to January 2023. Patients were categorized into 4 groups: group I (calcineurin inhibitor [CNI] + methotrexate [MTX] or mycophenolate mofetil [MMF]), group II (CNI + MTX or MMF + antithymocyte globulin [ATG]), group III (PTCy + ATG + CNI), and group IV (PTCy + CNI + MMF). PTCy was associated with a significant reduction in grade 2- 4 and grade 3-4 acute GVHD and moderate-to-severe chronic GVHD compared with CNI + MTX (or MMF)–containing regimens. PTCy did not increase relapse risk; PTCy reduced nonrelapse mortality, leading to improved GVHD-free/relapse-free survival (GRFS; Hazard Ratio, 0.4; P < .001). PTCy was also associated with improved overall survival. Bloodstream infections were increased with PTCy. The addition of ATG to PTCy did not further improve GRFS and was associated with a higher incidence of clinically significant cytomegalovirus (csCMV) and Epstein-Barr virus (csEBV) reactivation and a numerical increase in NRM. PTCy significantly appeared to improve GRFS in the MSD setting using PBSC grafts. The addition of ATG to PTCy increases csCMV and csEBV reactivation without further improving GRFS. Prospective trials and PTCy dose optimization are warranted.