Infusion hemolysis after pediatric major ABO-mismatched bone marrow transplant: Comparison of two red blood cell depletion techniques.

BACKGROUND: During major ABO-mismatched bone marrow transplant (BMT), the infusion of incompatible red blood cells (RBCs) that are present in the bone marrow graft can cause adverse events from hemolysis. RBC depletion of the bone marrow graft can decrease this risk, but the optimal method to prevent hemolysis is unclear. PROCEDURE: We conducted a retrospective cohort study of patients who underwent major ABO-mismatched BMT at a pediatric center and had RBC depletion with either hydroxyethyl starch (HES) sedimentation or Ficoll density gradient separation. Postinfusion hemoglobinuria and creatinine values were compared. RESULTS: Between 2002 and 2016, 37 patients received HES-treated and 16 patients received Ficoll-treated major ABO-mismatched bone marrow grafts. The median residual volume of RBCs was significantly greater with HES-treated grafts (HES 21.0 ml vs. Ficoll 1.4 ml, P < 0.0001). Patients who received HES-treated grafts had a higher prevalence of postinfusion hemoglobinuria (HES 57% vs. Ficoll 6%, P = 0.0009), but renal impairment was rare. Considering only HES-treated grafts, the volume of RBCs was not associated with either postinfusion hemoglobinuria or a creatinine increase. CONCLUSIONS: Ficoll density gradient separation achieves smaller RBC volumes and less postinfusion hemoglobinuria than HES sedimentation, but both can prevent significant hemolysis. Further studies are needed to determine the residual incompatible RBC volume threshold in major ABO-mismatched BMT.

Relative defects in mucosal immunity predict acute graft-versus-host disease.

Impairment of gut mucosal immunity by the transplant process could facilitate translocation of commensal bacteria and thereby augment the graft-versus-host response. To begin to assess the influence of gut mucosal immunity on the development of acute graft-versus-host disease (GVHD), we conducted a prospective study in 24 pediatric allogeneic hematopoietic cell transplant recipients, assessing 4 fecal markers of mucosal immunity: calprotectin, soluble CD8 (sCD8), soluble intracellular adhesion molecule 1, and ß-defensin-2. Stool samples were collected prospectively on transplant days 0, +5, +10, and +15 and analyzed by ELISA. Lower levels on day +5 (calprotectin and ß-defensin-2) and day +10 (calprotectin, ß-defensin-2, and sCD8) were associated with subsequent acute GVHD. The most striking difference was with calprotectin on day +10. Patients with levels below 424 mg/kg had an incidence of 77.8%, whereas those with levels above this threshold had a cumulative incidence of 0% (P = .002). Relative defects in gut mucosal immunity may be important in the pathogenesis of acute GVHD.

BCMA CAR-T induces complete and durable remission in refractory plasmablastic lymphoma.

Plasmablastic lymphoma (PBL) is a rare subtype of aggressive large B-cell lymphoma, with a dismal prognosis despite aggressive therapies. New approaches are needed for those with refractory disease. PBL expresses antigens similar to multiple myeloma (MM), including B-cell maturation antigen (BCMA). Chimeric antigen receptor T-cell (CAR-T) therapy directed against BCMA has shown efficacy for the treatment of heavily pretreated MM with low rates of grades 3 and 4 cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) in a phase Ib/II trial (A Study of JNJ-68284528, a CAR-T Directed Against BCMA in Participants With Relapsed or Refractory Multiple Myeloma (CARTITUDE-1), NCT03548207). However, data for the use of BCMA CAR-T for treating PBL are lacking.We report a challenging case of multiple refractory PBL that emerged from B-cell acute lymphoblastic leukemia in an adolescent who failed to respond to an allogeneic hematopoietic cell transplant. The patient developed rapidly advancing disease despite withdrawal of immunosuppression, treatment with etoposide, ibrutinib, and daratumumab, prompting consideration of BCMA CAR-T (under emergency investigational new drug (eIND)). The patient achieved a complete remission (CR), without recurrent acute graft versus host disease (GVHD), CRS or ICANS after BCMA CAR-T therapy. BCMA CAR-T expansion was detected in vivo, peaking on day 15. The patient remains in CR for more than a year post CAR-T therapy, supporting consideration of immunotherapy for future patients with refractory PBL, a disease with few treatment options.

Clinical outcomes and graft characteristics in pediatric matched sibling donor transplants using granulocyte colony-stimulating factor-primed bone marrow and steady-state bone marrow.

Matched sibling donor (MSD) transplant is a life-saving procedure for children with various hematological malignancies and non-malignancies. Traditionally, steady-state bone marrow (S-BM) has been used as the source of stem cells. More recently, peripheral blood stem cell (PBSC) after granulocyte-colony stimulating factor (G-CSF) mobilization has gained popularity. Adult studies of G-CSF-primed BM (G-BM) have shown that it produces rapid white blood cell engraftment like PBSC, but with less chronic graft-vs.-host disease. No such study has been published in pediatric patients. We conducted a pilot clinical trial of G-BM for pediatric patients. Ten patients were enrolled and were compared to a contemporaneous group of 12 patients who received S-BM. Patients in the G-BM group received a higher dose of total nucleated cells/kg (7.01 vs. 3.76 x 10(8), p = 0.0009), higher granulocyte-macrophage colony-forming units (CFU-GM)/kg (7.19 vs. 3.53 x 10(5), p = 0.01) and had shorter inpatient length of stay (28 vs. 40 days, p = 0.04). The engraftment, transfusion requirement and disease-free survival between the two groups were similar. We concluded that G-BM should be considered as an alternative graft source to S-BM, with the benefits of larger graft cell dose, higher CFU-GM dose and shorter length of stay.