TCRαβ/CD19 cell-depleted HLA-haploidentical transplantation to treat pediatric acute leukemia: updated final analysis

ABSTRACT

TCRαβ/CD19 cell depletion is a promising graft manipulation technique frequently used in the context of human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (HSCT). We previously reported the results of a phase I-II clinical trial (NCT01810120) to assess the safety and the efficacy of this type of exvivo T-cell depletion in 80 children with acute leukemia, showing promising survival outcomes. We now report an updated analysis on a cohort of 213 children with a longer follow-up (median, 47.6 months for surviving patients). With a 5-year cumulative incidence of nonrelapse mortality of 5.2% (95% confidence interval [CI], 2.8%-8.8%) and a cumulative incidence of relapse of 22.7% (95% CI, 16.9%-29.2%), projected 10-year overall and disease-free survival (DFS) were 75.4% (95% CI, 68.6%-80.9%) and 71.6% (95% CI, 64.4%-77.6%), respectively. Cumulative incidence of both grade II-IV acute and chronic graft-versus-host disease were low (14.7% and 8.1%, respectively). In a multivariable analysis for DFS including type of disease, use of total body irradiation in the conditioning regimen (hazard ratio [HR], 0.5; 95% CI, 0.26-0.98; P = .04), disease status at HSCT (complete remission [CR] ≥3 vs CR 1/2; HR, 2.23; 95% CI, 1.20-4.16; P = .01), and high levels of pre-HSCT minimal residual disease (HR, 2.09; 95% CI, 1.01-4.33; P = .04) were independently associated with outcome. In summary, besides confirming the good outcome results already reported (which are almost superimposable on those of transplant from HLA-matched donors), this clinical update allows the identification of patients at higher risk of treatment failure for whom personalized approaches, aimed at reducing the risk of relapse, are warranted.

Utilization of volumetric absorptive microsampling and dried plasma spot for quantification of anti-fungal triazole agents in pediatric patients by using liquid chromatography-tandem mass spectrometry

BACKGROUND

Recently, increasing attention has been paid to the use of microsampling techniques for therapeutic drug monitoring (TDM) in neonatal and pediatric populations. Volumetric Absorptive Microsampling (VAMS) has been introduced in the market under the name Mitra® (Neoteryx). These devices consist of porous absorbent tips that allow collection of fixed blood volumes (10-30 µL) to overcome the DBS-related hematocrit effect. Here, the authors analyzed the concentrations of triazole agents (voriconazole, posaconazole, and isavuconazole) in VAMS and dried plasma spot (DPS) samples.

METHODS

Fifty whole blood samples were obtained from pediatric patients subjected to systemic anti-fungal therapy. VAMS were collected by dipping the tip into whole blood before centrifugation for plasma recovery. Then, 30 µL of plasma was carefully spotted on filter paper to obtain DPS. Anti-fungal concentrations were measured using a validated LC-MS/MS kit (MassTox® Antimycotic Drugs/EXTENDED) provided by Chromsystems (Chromsystems Instruments & Chemicals). Drug concentrations in VAMS and DPS samples were compared to those in fresh plasma using Passing-Bablok and Bland-Altman tests.

RESULTS

Plasma concentrations of voriconazole, posaconazole, and isavuconazole were positively and significantly correlated with those obtained in VAMS and DPS samples (Spearman r range, 0.82-0.94, p < 0.001). Data were further analyzed using the Bland-Altman test, which showed a % mean difference compared to fresh plasma of -15.06-10.98 (range). The stability of both VAMS and DPS was ensured for at least 14 d at room temperature.

CONCLUSIONS

These results demonstrate that VAMS and DPS can be used for the TDM of anti-fungal agents. Owing to their stability, both sampling devices can be easily stored and shipped, without the need for refrigeration, to TDM laboratories that facilitate remote TDM applications. Finally, VAMS could be particularly suitable for pediatric and neonatal patients because they allow the collection of a few microliters of blood, thus improving ethical and compliance limitations.

Achievement of operational tolerance in a pediatric liver transplant recipient following successful hematopoietic stem cell transplantation from a different donor

Hematopoietic stem cell transplantation (HSCT)-based approaches are increasingly investigated strategies to induce tolerance in recipients of solid allografts. However, in the majority of cases, these approaches rely on the infusion of hematopoietic stem cells recovered from the same solid organ donor. In this report, we describe the case of a boy who received liver transplantation from a deceased donor, who had successfully underwent allogeneic HSCT from an unrelated donor for hepatitis-associated aplastic anemia. In this patient, it was possible to permanently withdraw post-HSCT immune suppression without causing any sign of liver graft dysfunction. To the best of our knowledge, this is the first case of operational tolerance documented in a patient who received combined liver transplantation and HSCT from different donors.

Allogeneic, donor-derived, second-generation, CD19-directed CAR-T cells for the treatment of pediatric relapsed/refractory BCP-ALL

Autologous CD19-directed chimeric antigen receptor (CAR)-T cells have shown unprecedented efficacy in children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, patients either relapsing after allogeneic hematopoietic stem cell transplantation (allo-HSCT) or displaying profound lymphopenia and/or rapidly progressing disease often cannot access autologous products. These hurdles may be overcome by allogeneic, donor-derived CAR-T cells. We tested donor-derived T cells transduced with a second-generation (4.1BB) CD19-directed CAR for treatment of patients with BCP-ALL in a hospital-exemption setting. Two constructs were tested: a retroviral construct incorporating the suicide gene inducible caspase-9 (CD19-CAR-Retro_ALLO) first and then a lentiviral construct and an automated, Prodigy-based manufacturing process (CD19-CAR-Lenti_ALLO). Thirteen children/young adults received ALLO-CAR-T cells between March 2021 and October 2022. Doses ranged between 1.0 × 106 and 3.0 × 106 CAR-T cells per kg. The toxicity profile was comparable with that of autologous CAR-T cells, characterized mainly by cytopenia, cytokine release syndrome (maximum grade 1), and grade 2 immune-effector cell-associated neurotoxicity syndrome. One case of acute graft-versus-host disease (GVHD) occurred and was rapidly controlled with steroids and ruxolitinib. None of the other patients, including 3 given ALLO-CAR-T cells from an HLA-haploidentical donor, experienced GVHD. Two patients received ALLO-CAR-T cells before HSCT and showed a significant expansion of CAR-T cells without any sign of GVHD. All patients obtained complete remission (CR) with absence of minimal residual disease in the bone marrow. With a median follow-up of 12 months (range, 5-21), 8 of 13 patients maintained CR. Allogeneic anti-CD19 CAR-T cells can effectively treat highly refractory BCP-ALL relapsing after allo-HSCT without showing increased toxicity as compared with autologous CAR-T cells.

First experience of combined enzyme replacement therapy and hematopoietic stem cell transplantation in alpha-mannosidosis

We describe the first case of bridge therapy in alpha-mannosidosis (AM) in an infant diagnosed at only 5 months of life who underwent enzyme replacement therapy (ERT) in the pre- and peri-transplant phases. Eight ERT infusions were administered before hematopoietic stem cell transplantation (HSCT) and continued for additional 90 days until complete engraftment. The clinical and laboratory data after 3 years post-HSCT show that the early combined intervention may reduce the disease progression and the urine and plasma content of mannosyl-oligosaccharides (OS) monitored by liquid chromatography tandem mass spectrometry (LC-MS/MS). This report highlights that early diagnosis and prompt initiation of such treatments in AM are the best chance to minimize the progression of symptoms.

Human leukocyte antigen evolutionary divergence influences outcomes of paediatric patients and young adults affected by malignant disorders given allogeneic haematopoietic stem cell transplantation from unrelated donors

High genetic heterogeneity in the human leukocyte antigen (HLA) increases the likelihood of efficient immune response to pathogens and tumours. As measure of HLA diversity, HLA evolutionary divergence (HED) has been shown to predict the response of tumours to immunotherapy and haematopoietic stem cell transplantation (HSCT) in adults. We retrospectively investigated the association of HED with outcomes of 153 paediatric/young adults patients, treated for malignant disorders with HSCT from 9-10/10 HLA-matched unrelated donors. HED was calculated as pairwise genetic distance between alleles in patient HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1, using the locus median to stratify patients with 'high' or 'low' HED. Patients with high HED-B and -DRB1 showed significantly improved disease-free survival (DFS), especially when combined (70.8% vs 53.7% p = 0.008). High HED-B + -DRB1 was also associated with improved overall survival (OS) (82.1 vs 66.4% p = 0.014), and concomitant reduction of non-relapse-mortality (5.1% vs 21.1% p = 0.006). The impact on OS and DFS of combined HED-B + -DRB1 was confirmed in multivariate analysis [hazard ratio (HR) 0.39, p = 0.009; and HR 0.45, p = 0.007 respectively]. Only high HED scores for HLA-DPB1 were associated, in univariate analysis, with reduced incidence of relapse (15.9% vs 31.1%, p = 0.03). These results support HED as prognostic marker in allogeneic HSCT and, if confirmed in larger cohorts, would allow its use to inform clinical risk and potentially influence clinical practice.

Immune Modulation Properties of Zoledronic Acid on TcRγδ T-Lymphocytes After TcRαβ/CD19-Depleted Haploidentical Stem Cell Transplantation: An analysis on 46 Pediatric Patients Affected by Acute Leukemia

TcRαβ/CD19-cell depleted HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents a promising new platform for children affected by acute leukemia in need of an allograft and lacking a matched donor, disease recurrence being the main cause of treatment failure. The use of zoledronic acid to enhance TcRγδ+ lymphocyte function after TcRαβ/CD19-cell depleted haplo-HSCT was tested in an open-label, feasibility, proof-of-principle study. Forty-six children affected by high-risk acute leukemia underwent haplo-HSCT after removal of TcRαβ+ and CD19+ B lymphocytes. No post-transplant pharmacological graft-versus-host disease (GvHD) prophylaxis was given. Zoledronic acid was administered monthly at a dose of 0.05 mg/kg/dose (maximum dose 4 mg), starting from day +20 after transplantation. A total of 139 infusions were administered, with a mean of 3 infusions per patient. No severe adverse event was observed. Common side effects were represented by asymptomatic hypocalcemia and acute phase reactions (including fever, chills, malaise, and/or arthralgia) within 24–48 h from zoledronic acid infusion. The cumulative incidence of acute and chronic GvHD was 17.3% (all grade I-II) and 4.8% (all limited), respectively. Patients given 3 or more infusions of zoledronic acid had a lower incidence of both acute GvHD (8.8 vs. 41.6%, p = 0.015) and chronic GvHD (0 vs. 22.2%, p = 0.006). Transplant-related mortality (TRM) and relapse incidence at 3 years were 4.3 and 30.4%, respectively. Patients receiving repeated infusions of zoledronic acid had a lower TRM as compared to those receiving 1 or 2 administration of the drug (0 vs. 16.7%, p = 0.01). Five-year overall survival (OS) and disease-free survival (DFS) for the whole cohort were 67.2 and 65.2%, respectively, with a trend toward a better OS for patients receiving 3 or more infusions (73.1 vs. 50.0%, p = 0.05). The probability of GvHD/relapse-free survival was significantly worse in patients receiving 1–2 infusions of zoledonic acid than in those given ≥3 infusions (33.3 vs. 70.6%, respectively, p = 0.006). Multivariable analysis showed an independent positive effect on outcome given by repeated infusions of zoledronic acid (HR 0.27, p = 0.03). These data indicate that the use of zoledronic acid after TcRαβ/CD19-cell depleted haploHSCT is safe and may result in a lower incidence of acute GvHD, chronic GvHD, and TRM.