Haploidentical hematopoietic cell transplantation using in vitro T cell depleted grafts as salvage therapy in patients with disease relapse after prior allogeneic transplantation

Donor-derived CD19 CAR-T Cells versus Chemotherapy Plus Donor Lymphocyte Infusion for Treatment of Recurrent CD19-positive B-ALL After Allogeneic Hematopoietic Stem Cell Transplantation

OBJECTIVE

This study aimed to compare the efficacy of anti-CD19 chimeric antigen receptor T cells (CAR-T cells) versus chemotherapy plus donor lymphocyte infusion (chemo-DLI) for treating relapsed CD19-positive B-cell acute lymphoblastic leukemia (B-ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

Clinical data of 43 patients with B-ALL who relapsed after allo-HSCT were retrospectively analyzed. Twenty-two patients were treated with CAR-T cells (CAR-T group), and 21 with chemotherapy plus DLI (chemo-DLI group). The complete remission (CR) and minimal residual disease (MRD)-negative CR rates, leukemia-free survival (LFS) rate, overall survival (OS) rate, and incidence of acute graft-versus-host disease (aGVHD), cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were compared between the two groups.

RESULTS

The CR and MRD-negative CR rates in the CAR-T group (77.3% and 61.5%) were significantly higher than those in the chemo-DLI group (38.1% and 23.8%) (P=0.008 and P=0.003). The 1- and 2-year LFS rates in the CAR-T group were superior to those in the chemo-DLI group: 54.5% and 50.0% vs. 9.5% and 4.8% (P=0.0001 and P=0.00004). The 1- and 2-year OS rates in the CAR-T versus chemo-DLI group were 59.1% and 54.5% vs. 19% and 9.5% (P=0.011 and P=0.003). Six patients (28.6%) with grade 2-4 aGVHD were identified in the chemo-DLI group. Two patients (9.1%) in the CAR-T group developed grade 1-2 aGVHD. Nineteen patients (86.4%) developed CRS in the CAR-T group, comprising grade 1-2 CRS in 13 patients (59.1%) and grade 3 CRS in 6 patients (27.3%). Two patients (9.1%) developed grade 1-2 ICANS.

CONCLUSION

Donor-derived anti-CD19 CAR-T-cell therapy may be better, safer, and more effective than chemo-DLI for B-ALL patients who relapse after allo-HSCT.

Donor Hematopoietic Stem Cell/Lymphocyte Maintenance Treatment After CAR T-Cell Therapy in Patients With B-Cell Acute Lymphoblastic Leukemia Relapse Following Stem Cell Transplant

Maintaining the efficacy of anti-CD19 chimeric antigen receptor modified (CAR) T-cell therapy in patients with B-cell acute lymphoblastic leukemia (B-ALL) relapse after allogeneic hematopoietic stem cell transplant (allo-HSCT) is an urgent problem. In this study, we aimed to compare the efficacy of donor hematopoietic stem cell infusion (DSI) therapy and donor lymphocyte infusion (DLI) therapy as a maintenance therapy after R/R B-ALL patients achieved CR in anti-CD19-CAR T-cell therapy but relapsed after allo-HSCT. In total, 22 B-ALL patients who relapsed after allo-HSCT received anti-CD19-CAR T-cell therapy. Patients who responded to CAR T-cell therapy received DSI or DLI as maintenance therapy. We compared the clinical responses, acute graft versus host disease (aGVHD), expansion of CAR-T-cells, and adverse events between the two groups. In our study, 19 patients received DSI/DLI as maintenance therapy. After DSI/DLI therapy, progression-free survival and overall survival were higher in the DSI group than in the DLI group at 365 days. The grades I and II of aGVHD was observed in four patients (36.4%) in the DSI group. Only one patient developed grade II aGVHD in the DLI group. The peaks of CAR T-cells in the DSI group were higher than those in the DLI group. IL-6 and TNF-α levels increased again in nine of 11 patients after DSI but not in the DLI group. Our findings indicate that for B-ALL patients who relapse after allo-HSCT, DSI is a feasible maintenance therapy if CR is obtained with CAR-T-cell therapy.

Sub-myeloablative Second Transplantations with Haploidentical Donors and Post-Transplant Cyclophosphamide have limited Anti-Leukemic Effects in Pediatric Patients

Pediatric patients with high-risk hematologic malignancies who experience relapse after a prior allogeneic hematopoietic cell transplant (HCT) have an exceedingly poor prognosis. A second allogeneic HCT offers the potential for long-term cure but carries high risks of both subsequent relapse and HCT-related morbidity and mortality. Using haploidentical donors for HCT (haploHCT) can expand the donor pool and potentially enhance the graft-versus-leukemia effect but is accompanied by a risk of graft-versus-host disease (GVHD). The goal of this protocol was to intensify the antileukemia effect of haploHCT for pediatric patients with hematologic malignancies that relapsed after prior allogeneic HCT, while limiting regimen-associated toxicities. This phase II clinical trial evaluated a sub-myeloablative preparative regimen consisting of anti-thymocyte globulin, clofarabine, cytarabine, busulfan, and cyclophosphamide, in combination with plerixafor to sensitize leukemic blasts. Participants received a mobilized peripheral blood unmanipulated haploidentical donor graft with one dose of post-transplant cyclophosphamide as GVHD prophylaxis, followed by natural killer (NK) cell addback. Here we report the clinical outcomes and immune reconstitution of 17 participants treated on the study and 5 additional patients treated on similar single-patient treatment plans. Of the 22 participants analyzed, 12 (55%) had active disease at the time of HCT. The regimen provided robust immune reconstitution, with 21 participants (95%) experiencing neutrophil engraftment at a median of 14 days after HCT. In this high-risk population, the overall survival was 45% (95% confidence interval [CI], 24%-64%), with a 12-month event-free survival of 31% (95% CI, 14%-51%) and cumulative incidence of relapse at 12 months of 50% (95% CI, 27%-69%). Four participants (18%) remain in remission at >5 years follow-up. Expected HCT-related organ-specific toxicities were observed, and 13 participants (59%) experienced acute or chronic GVHD. This intensified but sub-myeloablative regimen, followed by a high-dose unmanipulated haploidentical graft, post-transplantation cyclophosphamide, and NK cell infusion, resulted in adequate immune reconstitution but failed to overcome the elevated risks of relapse and treatment-related morbidity in this high-risk population.

Effects of second transplantation with T-cell-replete haploidentical graft using low-dose anti-thymocyte globulin on long-term overall survival in pediatric patients with relapse of leukemia after first allogeneic transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the preferred treatment for children with high-risk hematologic malignancies, but post-allo-HSCT relapse has a poor prognosis and limited treatment options. We evaluated the feasibility, outcome, and risk factors influencing survival after T-cell-replete haploidentical HSCT with low-dose anti-thymocyte globulin (ATG) in 30 patients with post-allo-HSCT relapse of acute lymphoblastic leukemia and acute myeloid leukemia. Overall, 50% of the patients had complete remission (CR) before the second transplant and the overall survival (OS) rate was 52%. In surviving patients (median follow-up 614 days), Kaplan-Meier analysis revealed estimated 2-year leukemia-free survival and OS rates of 48.1% and 61.1%, respectively. Cumulative incidences of 2-year non-relapse mortality and relapse were 24.7% and 36.3%, respectively. Achieving CR before the second allo-HSCT was a predominant independent prognostic factor identified in the multivariate analysis, with a significantly improved 2-year OS rate of 86.7%. T-cell-replete haplo-HSCT with low-dose ATG for second allo-HSCT may benefit a selected patient population.

New-Onset Severe Cytopenia After CAR-T Cell Therapy: Analysis of 76 Patients With Relapsed or Refractory Acute Lymphoblastic Leukemia

Although chimeric antigen receptor T (CAR-T) cell therapy has proven to be effective in treating relapsed or refractory B-cell hematological malignancies, severe hematological toxicities remain an intractable issue. This retrospective study assessed the characteristics and risk factors of new-onset severe cytopenia following CAR-T cell infusion in 76 patients with r/r acute lymphoblastic leukemia. The rates of new-onset severe cytopenia were high, including severe neutropenia (SN) (39/56, 70%), severe anemia (SA) (35/66, 53%), and severe thrombocytopenia (ST) (31/64, 48%). Comparatively, cohorts with higher cytokine release syndrome (CRS) grades had higher incidence of severe cytopenia with prolonged duration. Multivariable analyses showed that elevated maximum (max) lg D-dimer and delayed peak time of CRS are independent risk factors for SN recovery; increased max lg IL-10 and delayed CRS recovery are risk factors for SA; high max lg ferritin is a risk factor for ST; and longer period to CRS onset or CRS recovery and higher grade of CRS are risk factors for prolonged hematological toxicities. These observations led to the conclusion that profiles of CRS, including its duration, severity and serum markers are correlated to the incidence and recovery of new-onset severe cytopenia, prompting clinical intervention for post-CAR-T severe cytopenia.

Donor-derived anti-CD19 CAR T cells compared with donor lymphocyte infusion for recurrent B-ALL after allogeneic hematopoietic stem cell transplantation

The efficacy and safety of donor-derived anti-CD19 CAR T cells vs DLI for the management of relapsed B-cell acute lymphoblastic leukemia (B-ALL) after allo-hematopoietic stem cell transplantation (HSCT) remain unclear. Thirteen B-ALL patients with relapsed after allo-HSCT and thus were treated with donor-derived anti-CD19 CAR T-cell (study group). Fifteen B-ALL patients relapsed after allo-HSCT and thus were treated with DLI (DLI group). The rates of MRD-negative complete remission (61.5%) in the study group were significantly higher than those in the DLI group (13.3%) (p = 0.02). The complete remission duration in study group and DLI group were median 8.0 months (range, 3-25 months) and 4.4 months (range, 1-25 months; p = 0.026), respectively. The overall survival of patients in the study group was superior to that of the DLI group: 9.5 months (range,3-25 months) versus 5.5 months (range, 1-25 months; p = 0.030). One patient with grade 1 acute graft-versus-host disease (aGVHD) was identified in the study group. While five (33.3%) patients in the DLI group developed grades III-IV aGVHD. Three patients (23.07%) developed grade 3 or 4 cytokine release syndrome in the study group. This study suggested that donor-derived anti-CD19 CAR T-cell therapy is promising, safe, and potentially effective for relapsed B-ALL after allo-HSCT and may be superior to DLI.

Haploidentical transplants for patients with relapse after the first allograft

Relapse after allogeneic hematopoietic stem-cell transplantation (AHSCT) is associated with very poor outcomes. A second transplant offers the possibility of long-term disease control. We analyzed outcomes with haploidentical donors for second allograft at our institution. All consecutive patients with hematological malignancies (N = 29) who relapsed after AHSCT and underwent a haploidentical transplant (haploSCT) as second transplant between February 2009 and October 2018 were included. Median age was 36 years (interquartile range (IQR) 24-60); 83% of patients had high/very high disease risk index; 61% of AML/MDS patients had high-risk cytogenetics; and only 24% were in complete remission at transplant. With a median follow-up of 46.9 months, the 3-year relapse, non-relapse mortality (NRM), progression-free survival (PFS) and overall survival (OS) were 30%, 39%, 31% and 40%, respectively. In multivariable analysis (MVA), comorbidity index (HCT-CI) and detectable donor-specific anti-HLA antibodies (DSA) prior to second transplant were significantly associated with worse outcomes. Patients with HCT-CI <3 and without DSA had 3-year PFS and OS of 53% and 60.3%, respectively. Our findings suggest that haploSCT as second AHSCT is feasible and potentially curative. Lower HCT-CI and no DSA were associated with lower NRM and improved survival. Haploidentical grafts might be a preferred donor source for second AHSCT as these are high-risk patients who frequently need to proceed urgently to transplant.

Allogeneic hematopoietic stem cell transplantation from a 2-HLA-haplotype-mismatched family donor for posttransplant relapse: a prospective phase I/II study

HLA haploidentical hematopoietic stem cell transplantation (HSCT), i.e., HSCT from a 1-HLA-haplotype-mismatched family donor, has been successfully performed even as a second transplantation for posttransplant relapse. Is the haploidentical the limit of HLA mismatches in HSCT? In order to explore the possibility of HLA-mismatched HSCT from family donors beyond haploidentical relatives, we conducted a prospective phase I/II study of 2-HLA-haplotype-mismatched HSCT (2-haplo-mismatch HSCT). We enrolled 30 patients with posttransplant relapse (acute myeloid leukemia: 18, acute lymphoblastic leukemia: 11, non-Hodgkin lymphoma: 1). 2-haplo-mismatch HSCT was performed as the second to sixth transplantations. The donors were siblings (n = 12), cousins (n = 16), and second cousins (n = 2). The conditioning regimen consisted of fludarabine, cytarabine, melphalan, low-dose anti-thymocyte globulin, and 3 Gy of total body irradiation. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus, methylprednisolone, and mycophenolate mofetil. All patients achieved neutrophil engraftment, except for a case of early death. The cumulative incidences of grades II-IV and III-IV acute GVHD were 36.7% and 16.7%, respectively. The overall survival at 1 year, relapse, and non-relapse mortality rates was 30.1%, 38.9%, and 44.3%, respectively. Considering the poor prognosis of posttransplant relapse, 2-haplo-mismatch HSCT can be an alternative option in a second or third transplantation.

Allogeneic Donor-Derived Anti-CD19 CAR T Cell Is a Promising Therapy for Relapsed/Refractory B-ALL After Allogeneic Hematopoietic Stem-Cell Transplantation

INTRODUCTION

Currently, effective and safe salvage therapies are limited among patients with relapsed acute lymphoblastic leukemia after allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Anti-CD19 chimeric antigen receptor T (CAR T) cell is a promising treatment.

PATIENTS AND METHODS

We studied 11 patients with B-cell acute lymphoblastic leukemia that relapsed after allo-HSCT between September 2017 and October 2019. Patients were treated with a dose of single-infusion donor-derived anti-CD19 CAR T cells.

RESULTS

Eight patients (72.7%) experienced morphologic remissions. Seven (63.6%) experienced minimal residual disease-negative remission. The ongoing complete remission (CR) duration of 2 patients reached 22 months. The median overall survival was 9 months (range, 2-22 months). Only one patient with grade 1 acute graft-versus-host disease was observed. Two patients (18.2%) developed grade 3/4 cytokine release syndrome.

CONCLUSION

This prospective study showed allogeneic donor-derived anti-CD19 CAR T-cell therapy is an effective and safe salvage regimen for patients with relapsed/refractory B-cell acute lymphoblastic leukemia after allo-HSCT. Further randomized and multicenter investigations are needed to evaluate their potential role in relapsed acute lymphoblastic leukemia therapies after allo-HSCT.

Retrospective single center analysis of outcome, risk factors and therapy in steroid refractory graft-versus-host disease after allogeneic hematopoietic cell transplantation

Acute and chronic graft-vs.-host disease (aGvHD and cGvHD) are major complications after allogeneic hematopoietic cell transplantation (HCT) leading to substantial morbidity and mortality. This retrospective single-center study analyzes incidence, therapy, and outcome of GvHD in n = 721 patients ≥18 years having received allogeneic HCT 2004-2013 with a special focus on steroid refractory GvHD. Acute (n = 355/49.2%) and chronic (n = 269/37.3%) GvHD were mainly treated by steroids in first-line therapy. The proportion of steroid refractory aGvHD and cGvHD was 35.7% and 31.4%, respectively. As there is no standard therapy for steroid refractory GvHD, a range of different agents was used. In aGvHD, the overall response rate (ORR) of steroid refractory GvHD to second-line treatment was 27.4%. Mycophenolate mofetil (MMF) and mTOR inhibitors led to superior response rates (ORR 50.0% and 53.3%, respectively). In steroid refractory cGvHD therapy, ORR was 44.4%. Use of calcineurin inhibitors (CNI; n = 11/45.5%), MMF (n = 18/50.0%), mTOR inhibitors (n = 10/60.0%), and extracorporeal photophoresis (ECP; n = 16/56.3%) showed ORR above average. Targeted therapies lead to responses in 7.7% (n = 13). This data may help to improve the design of future prospective clinical studies in GvHD.

Depletion of αβ+ T and B Cells Using the CliniMACS Prodigy: Results of 10 Graft-Processing Procedures from Haploidentical Donors

Background

Depletion of TCRαβ+ T cells and B cells with the CliniMACS Plus® has been used for haploidentical hematopoietic stem cell transplantation for a decade. The depletion procedure is time and labour demanding and with variable reported efficiencies. Recently, an automated procedure was launched for the CliniMACS Prodigy® (Miltenyi Biotec) but reported data are scarce. Here, we report the results of the first ten TCRαβ+ and B cell depletion procedures for clinical use performed at our centre.

Materials and Methods

All transplants were from a parent to a child. Collection of peripheral blood stem cells was performed after filgrastim mobilisation by use of the Spectra Optia® (TerumoBCT) set on the MNC program. Because of insufficient hematopoietic stem cell mobilisation, 1 donor received additional plerixafor.

Results

We performed ten uncomplicated processes with the CliniMACS Prodigy. We found the results of the depletion procedures satisfactory with a median log reduction of TCRαβ+ cells of -4.21 (range -3.98 to -4.74), resulting in a median number of TCRαβ+ cells in the depleted product of 28.6 × 10³/kg recipient weight (range 14.9-69.7 × 10³/kg). The median CD34 recovery was 83% (range 70-100). To achieve a sufficient number of CD34+ cells, we performed an additional CD34+ enrichment procedure using the CliniMACS Plus for 3 patients. The B cell depletion was slightly less efficient with a median log reduction of -3.72 (range -2.83 to -4.20).

Conclusion

Overall, we found the TCRαβ and CD19 depletion procedure on the CliniMACS Prodigy easy to handle and reliable, providing reproducible good results.

Second allogeneic hematopoietic cell transplantation enables long-term disease-free survival in relapsed acute leukemia

Allogeneic hematopoietic cell transplantation (HCT) is the treatment of choice for high-risk myeloid and lymphoid leukemias. Relapse after allogeneic HCT is associated with a dismal prognosis and further therapeutic options are limited. One potential curative approach is a second allogeneic HCT. However, there is no consensus about optimal transplant modalities, suitable patients, and entities. We performed a retrospective analysis of our institutional database to evaluate risk factors that influence survival after a second allogeneic HCT for the treatment of relapsed acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). We identified 40 patients (AML, n = 29; ALL, n = 11) that received a second allogeneic HCT at our institution. At time of second HCT, 48% of patients were in complete remission (CR). Current overall survival (OS) was 14/40 patients with a median follow-up of 64 months (range 4-140) of patients alive resulting in a Kaplan-Meier estimated 2-year event-free survival (EFS) and OS of 32%, respectively. Cumulative incidence of non-relapse mortality (NRM) and relapse at 2 years was 31 and 37%, respectively. We identified several independent risk factors influencing OS: > 6 months from first to second transplant (p = 0.02), complete remission prior to transplant (p = 0.003), and the subsequent occurrence of chronic graft-versus-host disease (p = 0.003) were associated with a significantly improved OS. In conclusion, our data suggest that a second allogeneic HCT is a curative treatment option for relapsed acute leukemias in selected patients.