Generation of universal “off-the-shelf” chimeric antigen receptor (CAR)-engineered T-cells from induced pluripotent stem cells

The development of autologous chimeric antigen receptor (CAR) T-cells has resulted in a paradigm shift in the therapeutic treatment landscape of patients with hematological malignancies. However, the production of autologous CAR T-cell therapies has known disadvantages, including cost of the process, manufacture failure in some patients, and the lengthy manufacturing process which delays availability of treatment.1 The development of CAR-engineered T cell-derived induced pluripotent stem cells (TiPSCs) have the potential to serve as an abundant source of functional therapeutic CAR-T lymphocytes; however, the presence of an innate-like, allo-reactive phenotype associated with TiPSCs may give rise graft-versus-host disease (GvHD) in recipients.2

At the 3rd European CAR T-cell Meeting, organized by the European Society for Blood and Marrow Transplantation (EBMT), and the European Hematology Association (EHA), Alexandros Nianias, MSc, of Amsterdam University Medical Centers, Amsterdam, Netherlands, presented results of a proof-of-concept study aiming to generate CAR-engineered T cell-derived induced pluripotent stem cells (TiPSCs) with adaptive immune features that can be used as a universal, “off-the-shelf” CAR-T approach.

In order to diminish alloreactivity, immunogenicity and NK cell-mediated rejection mechanisms, the TiPSC-derived CAR T-cells were genetically modified and differentiated towards a T-cell lineage using homologous recombination and CRISPR/Cas9 gene editing of the loci in TiPSCs that gives rise to an allo-reactive phenotype.

 

Subsequently, the CAR-engineered TiPSC were found not to be immunogenic and demonstrated in vitro anti-tumor ability, supporting the use of TiPSC-derived CAR T-cells as a potential strategy for the development of “off-the-shelf” CAR-T products that can overcome limitations in manufacturing, efficacy, and applicability of cellular therapeutics.

CAR-Hematotox: a multivariate score to predict hematotoxicity after CAR T-cell therapy for relapsed/refractory B-cell lymphoma

CD19-targeted chimeric antigen receptor (CAR) T-cell immunotherapy has previously demonstrated impressive efficacy results in B-cell malignancies. However, immune-related toxicities such as cytokine release syndrome (CRS) and neurotoxicity can be life-threatening in a subset of patients receiving CAR T-cell therapy, and guidelines are in place for the management of these immune-related adverse events.3 Currently, the incidence of hematotoxicity in patients with B-cell malignancies receiving CD19-specific CAR T-cell therapy remains poorly understood.

Kai Rejeski, MD, of LMU Hospital Munich, Munich, Germany, presents the findings of a multicenter, retrospective study aiming to characterize the influence of patient clinical features of neutropenia and develop a clinical score predictive of hematotoxicity.

Peripheral blood counts of 128 patients who received axicabtagene ciloleucel (axi-cel, n=75) or tisagenlecleucel (tisa-cel, n=53) were longitudinally analyzed. The incidence of cytopenias was graded and the impact on baseline clinical and laboratory markers of hematotoxicity was analyzed.

The incidence of profound and prolonged neutropenia across all studied patients were 75.0% and 73.8%, respectively. There was a greater incidence of hematotoxicity and longer duration of neutropenia associated with patients treated with axi-cel (12 vs. 10 days, p=0.02). Using the findings from the analysis, the CAR-HEMATOTOX score was developed and was found to be highly predictive of severe neutropenia in the training cohort. A subsequent study in the independent validation cohort confirmed a higher incidence of cytopenia and longer duration of neutropenia for high-risk patients (12.5 vs. 7 days, p=0.0002).

In conclusion, hematotoxicity represents a frequent immune-related adverse event in patients treated with CD19-specific CAR T-cell therapy, and the CAR-HEMATOTOX score may be of use to clinicians to help risk-stratify for this toxicity and guide treatment strategies.

Safety and efficacy of ARI-0001 cells in adult and pediatric patients with R/R B-cell ALL with isolated extramedullary disease

The prognosis of patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) who have relapsed following allogeneic hematopoietic cell transplantation remains poor.4 However, the approval of tisagenlecleucel for patients with refractory disease has improved the outcomes of R/R B-ALL.5 Although outcomes have improved, patients with isolated extramedullary disease (IED), are not included in the label for tisagenlecleucel use, representing a patient population with an unmet clinical need.

At the 3rd European CAR T-cell Meeting, Valentín Ortiz-Maldonado, MD, of the Hospital Clínic de Barcelona, Barcelona, Spain, outlined safety and efficacy outcomes of ARI-0001 CART-19 cell therapy in patients with R/R B-ALL with IED.

In this Phase I study (NCT03144583), 15 patients with IED R/R ALL received ARI-0001 cells, and the incidence of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) was analyzed using the ASTCT 2019 consensus grading guidelines.

Any grade CRS occurred in 40% (6/15) of patients, of which 1 patient with grade 2 CRS was treated with tocilizumab; there was no reported incidence of ICANS. Best overall response was seen in 93.3% (14/15) of patients, with complete responses seen in 73% (11/15) of patients.

Progression-free survival was 57% (95% CI: 37–90%) at 2 years. Duration of response at 2 years was 62% (95% CI: 40– 95%) for all responders and 73% (95% CI: 51–100%) for patients who achieved a complete response.

ARI-0001 cells in R/R ALL with IED demonstrated a similar safety profile to other CD-19-targeting CAR-T products and were able to achieve longer-term remission in patients with R/R IED B-ALL.

COVID-19 in Hematopoietic Cell Transplant Recipients: A CIBMTR Study

Patients who have recently undergone hematopoietic stem cell transplantation (HSCT) are at high risk from SARS-Cov-2 infection on the basis of their immunosuppressed status.6 Organizations such as the Center for International Blood and Marrow Transplant Research (CIBMTR) have been working to collect data to establish the impact and risk factors of COVID-19 on patients who have undergone HSCT.

At the Transplantation & Cellular Therapy Meetings of the American Society for Transplantation and Cellular Therapy (ASTCT) and the CIBMTR, Akshay Sharma, MBBS, St. Jude Children’s Research Hospital, Memphis, TN, presented the findings of an analysis of 318 HSCT recipients (184 allogeneic HSCT and 134 autologous HSCT) who were diagnosed with COVID-19 and reported to the CIBMTR.7

In this analysis, COVID-19 disease severity was mild in 49% of patients and severe in 14% of HSCT patients. The overall probability of survival was 68% at 30 days after a COVID-19 diagnosis. In this patient population, age over 50 years, male sex, and development of COVID-19 within 12 months of transplantation were associated with a higher risk of mortality.

In conclusion, this analysis identified risk factors for increased mortality among transplant recipients including age, sex, and time from transplant. Identifying at-risk patients may help provide a rationale for the vaccination of HSCT recipients against COVID-19 infection.

Immunotherapy with Ex Vivo-Expanded Cord Blood (CB)-Derived NK Cells Combined with High-Dose Chemotherapy (HDC) and Autologous Stem Cell Transplant (ASCT) for B-Cell Non-Hodgkin’s Lymphoma (NHL)

High-dose chemotherapy (HDC) and autologous stem cell transplant (ASCT) is an established treatment approach for patients with relapsed B-cell non-Hodgkin’s lymphoma (NHL).8 Following relapse, outcomes remain poor and, accordingly, novel approaches combining HDC with immunotherapy are being evaluated in this setting, including natural killer cell (NK) approaches.

At the TCT 2021 meeting, Yago Nieto, MD, PhD, University of Texas MD Anderson Cancer Center, Houston, TX, presented the results of a Phase I study evaluating the use of “off-the-shelf” cord blood-derived NK cells in patients with B-cell NHL receiving HDC/ASCT.

In this study, cord blood-derived NK cells were expanded and infused in 20 patients with B-NHL, without consideration of HLA matching in the recipient. The primary endpoint of this study was safety, and secondary endpoints included relapse-free survival (RFS) and overall survival (OS).

Infusion with cord blood-derived NK cells was detected for a mean of 2 weeks in peripheral blood and NK persistence was not affected by the degree of HLA mismatch by the recipient. Cord blood-derived NK cells did not result in any adverse events among patients, including no incidence of cytokine release syndrome, neurotoxicity or graft-versus-host disease.

At a median follow-up of 18 months, 13 patients were alive and in remission (68% RFS), 16 patients were alive (84% OS) and of note, 11 of the 16 diffuse large B-cell lymphoma patients (69%) remained in remission.

The results of this investigation suggest that cord blood-derived NK cells in combination with HDC and ASCT is a safe approach for patients with B-NHL and demonstrates promising improvements in patient survival.

Inferior Clinical Outcomes in Recipients of Cryopreserved Grafts Following Reduced Intensity Conditioning Allogeneic Hematopoietic Cell Transplantation: A Single Center Report

The COVID-19 pandemic has created barriers to timely donor evaluation, cell collection, and graft transplant for allogeneic hematopoietic stem cell transplantation (allo-HCT).9 As a result of the pandemic, the cryopreservation of allogeneic donor apheresis products has been implemented in many sites to overcome these challenges.

In this abstract from the Transplantation & Cellular Therapies (TCT) 2021 virtual meeting, Andriyana K. Bankova, MD, of Stanford University School of Medicine, Stanford, CA, discusses the results of an institutional study evaluating clinical post-HCT outcomes in patients who received cryopreserved grafts.

In addition, differences in graft composition of cryogenically preserved and fresh products were investigated by assessing immunophenotypes of stem cells and lymphocyte subsets.

Data from 29 patients who underwent allo-HCT with cryogenically preserved products were compared to a control cohort of 60 patients who received fresh peripheral blood stem cell (PBSC) allo-HCT. The primary endpoints of this evaluation were overall survival (OS) and graft failure; secondary endpoints included hematopoietic recovery and incidence of graft-versus-host disease (GvHD).

In total, 13.8% (4/29) of patients in the cryopreserved group developed primary graft failure in comparison to 1.7% (1/60) in the fresh group. Patients in the cryopreserved group also showed inferior OS (p=0.023), and slower recovery of neutrophils (p=0.006) and platelets (p=0.058). The incidence of acute GvHD was similar between the two groups; however, flow cytometry revealed significantly lower counts of NK cells in the cryopreseved group compared with fresh PBSC allo-HCT (p=0.0159).

The findings from this study suggest that the use of cryopreserved allogeneic donor apheresis products results in inferior OS and a difference in graft composition between the two approaches.

References

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  2. Amir A, van der Steen D, Hagedoorn R, et al. Allo-HLA–reactive T cells inducing graft-versus-host disease are single peptide specific. Blood. 2011;118(26):6733–6742.
  3. Hirayama A, Turtle C. Toxicities of CD19 CAR‐T cell immunotherapy. American Journal of Hematology. 2019;94(S1):S42–S49.
  4. Gökbuget N, Stanze D, Beck J, et al. Outcome of relapsed adult lymphoblastic leukemia depends on response to salvage chemotherapy, prognostic factors, and performance of stem cell transplantation. Blood. 2012;120(10):2032–2041.
  5. Halford Z, Anderson M, Bennett L, et al. Tisagenlecleucel in Acute Lymphoblastic Leukemia: A Review of the Literature and Practical Considerations. Annals of Pharmacotherapy. 2020;55(4):466–479.
  6. Ardura M, Hartley D, Dandoy C et al. Addressing the Impact of the Coronavirus Disease 2019 (COVID-19) Pandemic on Hematopoietic Cell Transplantation: Learning Networks as a Means for Sharing Best Practices. Biology of Blood and Marrow Transplantation. 2020;26(7):e147–e160.
  7. Sharma A, Bhatt N, St Martin A, et al. Clinical characteristics and outcomes of COVID-19 in haematopoietic stem-cell transplantation recipients: an observational cohort study. The Lancet Haematology. 2021;8(3):e185–e193.
  8. Thuresson P, Vander Velde N, Gupta P, Talbot J. A Systematic Review of the Clinical Efficacy of Treatments in Relapsed or Refractory Diffuse Large B Cell Lymphoma. Advances in Therapy. 2020;37(12):4877–4893.
  9. Hamadani M, Zhang M, Tang X, et al. Graft Cryopreservation Does Not Impact Overall Survival after Allogeneic Hematopoietic Cell Transplantation Using Post-Transplantation Cyclophosphamide for Graft-versus-Host Disease Prophylaxis. Biology of Blood and Marrow Transplantation. 2020;26(7):1312–1317.

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