T cell receptor gene-modified allogeneic T cells with siRNA for endogenous T cell receptor induce efficient tumor regression without graft-versus-host disease

Adoptive immunotherapy using genetically engineered patient-derived lymphocytes to express tumor-reactive receptors is a promising treatment for malignancy. However, utilization of autologous T cells in this therapy limits the quality of gene-engineered T cells, thereby inhibiting the timely infusion of the cells into patients. In this study, we evaluated the anti-tumor efficacy and the potential to induce graft-versus-host disease (GVHD) in T cell receptor (TCR) gene-engineered allogeneic T cells that downregulate the endogenous TCR and HLA class I molecules with the aim of developing an "off-the-shelf" cell product with expanded application of genetically engineered T cells. We transduced human lymphocytes with a high-affinity TCR specific to the cancer/testis antigen NY-ESO-1 using a novel retrovirus vector with siRNAs specific to the endogenous TCR (siTCR vector). These T cells showed reduced expression of endogenous TCR and minimized reactivity to allogeneic cells in vitro. In non-obese diabetic/SCID/γcnull mice, TCR gene-transduced T cells induced tumor regression without development of GVHD. A lentivirus-based CRISPR/Cas9 system targeting β-2 microglobulin in TCR gene-modified T cells silenced the HLA class I expression and prevented allogeneic CD8+ T cell stimulation without disrupting their anti-tumor capacity. This report is the first demonstration that siTCR technology is effective in preventing GVHD. Adoptive cell therapy with allogeneic T cells engineered with siTCR vector may be useful in developing an "off-the-shelf" therapy for patients with malignancy.

Case Report: Unedited allogeneic chimeric antigen receptor T cell bridging to conditioning-free hematopoietic stem cell transplantation for a child with refractory Burkitt lymphoma

Purpose

Burkitt lymphoma (BL) is the most common tumor of non-Hodgkin's lymphoma (NHL) in children, accounting for about 40% of cases. Although different combined short-course chemotherapies have achieved a good effect, refractory/relapsed BL has a poor prognosis with cure rates less than 30%. Chimeric antigen receptor T cell (CAR-T) therapy has developed rapidly in recent years and achieved excellent results in acute lymphoblastic leukemia (ALL). However, in some cases, there is a failure to produce autologous CAR-T cells because of T-cell dysfunction. In such cases, allogeneic CAR-T therapy has to be considered.

Methods

A 17-year-old boy with stage II BL did not respond to extensive chemotherapy and sequential autologous CAR-T therapy. Lentiviral vectors containing anti-CD20-BB-ζ (20CAR) and anti-CD22-BB-ζ (22CAR) transgenes were used to modify the T cells from an HLA-identical matched unrelated donor. Flow cytometry was used to assess the cytokine analyses and CAR-T cell persistence in peripheral blood, enumerated by qPCR as copies per ug DNA. Informed consent for autologous/allogeneic CAR-T therapy was obtained from the patient and his legal guardian.

Results

Unedited HLA-matched allogeneic CD20 and CD22 CAR-T cells were infused after lymphodepletion chemotherapy with cyclophosphamide and fludarabine. The patient experienced Grade IV cytokine release syndrome (CRS) and went into complete remission (CR) after anti-inflammatory treatment including tocilizumab. Because of persistent pancytopenia and full donor chimerism, the same donor's conditioning-free peripheral blood stem cells were successfully transplanted 55 days post CAR-T. Neutrophils were engrafted at day +11 and platelets were rebuilt at day +47 without obvious acute graft-versus-host disease (GVHD), but there was mild chronic GVHD in the skin and eyes. Currently, active anti-rejection therapy is still underway.

Conclusion

Unedited HLA-matched allogeneic CAR-T cell therapy could be an innovative, effective, and safe treatment for children with refractory/relapse BL without obvious acute GVHD. Conditioning-free allogeneic hematopoietic stem cell transplantation (HSCT) from the same donor is feasible for a patient with full donor T-cell chimerism after allogeneic CAR-T. It cannot be ignored that close GVHD monitoring is needed post HSCT.

Convergence or divergence: next frontiers toward globalization of current- and next-generation cell and gene therapies

The last decades have seen a massive transformation in the field of advanced therapies, culminating in the marketing approval of different cutting-edge gene, cell- and tissue engineering-based therapies across different regions of the world. Although this success is promising, the global clinical development pathway of such therapies is often hindered by unique manufacturing, preclinical and clinical regulatory challenges; with different expectations, sometimes linked with divergence in opinions between international regulatory authorities. Such technologies call for a science-based approach and an early regulatory dialogue to set the key elements of quality, safety and efficacy for the next generation cell and gene therapies that can be harmonized across different regional jurisdictions, hence speeding up patient access to innovative therapies across the globe.

Intracoronary Administration of Allogeneic Cardiosphere-Derived Cells Immediately Prior to Reperfusion in Pigs With Acute Myocardial Infarction Reduces Infarct Size and Attenuates Adverse Cardiac Remodeling

BACKGROUND

Allogeneic cardiosphere-derived cells (CDCs) exert cardioprotective effects when administered intracoronarily after reperfusion in animal models of acute myocardial infarction (AMI). The "no-reflow" phenomenon develops rapidly post-reperfusion and may undermine the efficacy of cell therapy, due to poor cell delivery in areas of microvascular obstruction (MVO). We hypothesized that CDC-induced cardioprotection would be enhanced by cell administration prior to reperfusion, when microvasculature is still relatively intact, to facilitate widespread cell delivery within the ischemic area.

METHODS AND RESULTS

We studied 81 farm pigs; 55 completed the specified protocols. A dose-optimization study in infarcted pigs demonstrated that the doses of 5 million and 10 million CDCs are the maximum safe doses that can be administered intracoronarily at 5 minutes prior to and at 5 minutes post-reperfusion, respectively, without aggravating MVO. Quantification of acute cell retention by polymerase chain reaction demonstrated that cell delivery prior to reperfusion resulted in higher cardiac cell retention compared to delivery post-reperfusion. We then performed a randomized, placebo-controlled study to assess the long-term efficacy of intracoronary infusion of 5 million allogeneic CDCs, delivered at 5 minutes prior to reperfusion, in a porcine model of AMI. The CDC therapy resulted in decreased scar size, improved regional systolic function, and attenuation of adverse cardiac remodeling (manifested as preserved global systolic function, preserved end-systolic volume, and decreased interstitial fibrosis) compared to placebo at 30 days post-MI.

CONCLUSIONS

Dose-optimized intracoronary infusion of allogeneic CDCs prior to reperfusion in a porcine model of AMI is feasible, safe and confers long-term benefits.

Limiting glioma development by photodynamic therapy-generated macrophage vaccine and allo-stimulation: an in vivo histological study in rats

Immunotherapy of brain tumors involves the stimulation of an antitumor immune response. This type of therapy can be targeted specifically to tumor cells thus sparing surrounding normal brain. Due to the presence of the blood-brain barrier, the brain is relatively isolated from the systemic circulation and, as such, the initiation of significant immune responses is more limited than other types of cancers. The purpose of this study was to show that the efficacy of tumor primed antigen presenting macrophage (MaF98) vaccines can be increased by: (1) photodynamic therapy (PDT) of the priming tumor cells and (2) intracranial injection of allogeneic glioma cells directly into the tumor site. Experiments were conducted in an in vivo brain tumor development model using Fischer rats and F98 (syngeneic) and BT4C (allogeneic) glioma cells. The results showed that immunization with Ma (acting as antigen-presenting cells), primed with PDT-treated tumor cells (MaF98), significantly slowed but did not prevent the growth of F98-induced tumors in the brain. Complete suppression of tumor development was obtained via MaF98 inoculation combined with direct intracranial injection of allogeneic glioma cells. No deleterious effects were noted in any of the animals during the 14-day observation period.

Cranial reconstruction using allogeneic mesenchymal stromal cells: A phase 1 first-in-human trial

Cranioplasty is necessary for patients that have undergone craniectomy following trauma, stroke or other causes of elevated intracranial pressure. This study assessed the effectiveness of treating cranial defects with allogeneic mesenchymal stromal cells (MSC) on a ceramic carrier and polymer scaffold, to produce viable bone and healing of a cranial void. Patients underwent a baseline computed tomography (CT) scan for construct design. Two sets of interlocking moulds were three-dimensional printed to enable shaping of two polymer meshes, which formed the boundaries of the construct corresponding to restoration of the skull interna and externa. In vitro expanded donor MSC were seeded onto ceramic granules in a good manufacturing practices facility. The inner mesh was placed in theatre, followed by the cell-loaded granules, and the outer mesh. Patients were followed-up at 3, 6 and 12 months and cosmesis assessed visually, while bone formation was assessed by CT scans at 1 day, 3 months and 12 months. Manufacture of the construct and surgery was uneventful for all three patients. Initial cosmesis was excellent with no complications. New bone formation was demonstrated by analysis of CT data; however, bone resorption was noted in all 3 cases on the 12-month CT scan. The lack of rigidity of the construct in an environment with continuous pulsatile movement may be preventing the formation of solid bone. It is possible to produce a customized allogeneic MSC construct for cranial reconstruction to replace cranial bone with good cosmesis, using a combination of medical computer modelling, rapid-prototyping and tissue engineering.

Allogeneic DCG promote lung NK cell activation and antitumor effect after invariant NKT cell activation

AIM

We aimed to investigate whether allogeneic dendritic cells pulsed with alpha-galactosylceramide (DCG) treatment induces activation of Natural Killer T (NKT) cells.

MATERIALS AND METHODS

C57BL/6 and BALB/c mice were injected with syngeneic and allogeneic DCG. We then examined NK and NKT cell activity in the lung and spleen and antitumor effect in various lung tumor metastatic models.

RESULTS

While splenic NKT activity was suppressed after allogeneic DCG treatment, allogeneic DCG treatment induced similar antitumor effect as well as lung NKT and NK cell activity compared to syngeneic DCG treatment. Furthermore, allogeneic DCG treatment prolonged survival in B16F10, LLC, Pan02, MethA, and CT26 tumor models in two strains of mice.

CONCLUSION

This allogeneic DCG treatment could be substituted for syngeneic DCG treatment. The results obtained in the present study suggest that allogeneic DCG treatment may provide a new approach in cancer immunotherapy with NKT cells.

Suppression of the immune system as a critical step for bone formation from allogeneic osteoprogenitors implanted in rats

The surface marker profile of mesenchymal stromal cells (MSCs) suggests that they can escape detection by the immune system of an allogeneic host. This could be an optimal strategy for bone regeneration applications, where off-the-shelf cells could be implanted to heal bone defects. However, it is unknown how pre-differentiation of MSCs to an osteogenic lineage, a means of improving bone formation, affects their immunogenicity. Using immunohistological techniques in a rat ectopic implantation model, we demonstrate that allogeneic osteoprogenitors mount a T cell- and B cell-mediated immune response resulting in an absence of in vivo bone formation. Suppression of the host immune response with daily administration of an immunosuppressant, FK506, is effective in preventing the immune attack on the allogeneic osteoprogenitors. In the immunosuppressed environment, the allogeneic osteoprogenitors are capable of generating bone in amounts similar to those of syngeneic cells. However, using osteoprogenitors from one of the allogeneic donors led to newly deposited bone that was attacked by the host immune system, despite the continued administration of the immunosuppressant. This suggests that, although using an immunosuppressant can potentially suppress the immune attack on the allogeneic cells, optimizing the dose of the immunosuppressant may be crucial to ensure bone formation within the allogeneic environment. Overall, allografts comprising osteoprogenitors derived from allogeneic MSCs have the potential to be used in bone regeneration applications.