Concise Review: Emerging Principles from the Clinical Application of Chimeric Antigen Receptor T Cell Therapies for B Cell Malignancies

Impact of fludarabine and treosulfan on ovarian tumor cells and mesothelin chimeric antigen receptor T cells

In addition to their immunosuppressive effect, cytostatics conditioning prior to adoptive therapy such as chimeric antigen receptor (CAR) T cells may play a role in debulking and remodeling the tumor microenvironment. We investigated in vitro the killing efficacy and impact of treosulfan and fludarabine on ovarian cancer cells expressing mesothelin (MSLN) and effect on MSLN-targeting CAR T cells. Treosulfan and fludarabine had a synergetic effect on killing of SKOV3 and OVCAR4 cells. Sensitivity to the combination of treosulfan and fludarabine was increased when SKOV3 cells expressed MSLN and when OVCAR4 cells were tested in hypoxia, while MSLN cells surface expression by SKOV3 and OVCAR4 cells was not altered after treosulfan or fludarabine exposure. Exposure to treosulfan or fludarabine (10 µM) neither impacted MSLN-CAR T cells degranulation, cytokines production upon challenge with MSLN + OVCAR3 cells, nor induced mitochondrial defects. Combination of treosulfan and fludarabine decreased MSLN-CAR T cells anti-tumor killing in normoxia but not hypoxia. In conclusion, treosulfan and fludarabine killed MSLN + ovarian cancer cells without altering MSLN-CAR T cells functions (at low cytostatics concentration) even in hypoxic conditions, and our data support the use of treosulfan and fludarabine as conditioning drugs prior to MSLN-CAR T cell therapy.

Improving the safety of CAR-T-cell therapy: The risk and prevention of viral infection for patients with relapsed or refractory B-cell lymphoma undergoing CAR-T-cell therapy

Chimeric antigen receptor (CAR) T-cell therapy, an innovative immunotherapeutic against relapsed/refractory B-cell lymphoma, faces challenges due to frequent viral infections. Despite this, a comprehensive review addressing risk assessment, surveillance, and treatment management is notably absent. This review elucidates immune response compromises during viral infections in CAR-T recipients, collates susceptibility risk factors, and deliberates on preventive strategies. In the post-pandemic era, marked by the Omicron variant, new and severe threats to CAR-T therapy emerge, necessitating exploration of preventive and treatment measures for COVID-19. Overall, the review provides recommendations for viral infection prophylaxis and management, enhancing CAR-T product safety and recipient survival.

Persistent Cytopenia After CD19 CAR T Therapy in Relapsed/Refractory DLBCL Patients Could Be a Predictor of Efficacy and Side Effects

Hematological toxicity is a severe adverse event (AE) in anti-CD19 chimeric antigen receptor (CAR) T cell therapy for relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). However, the pathophysiological mechanism underlying prolonged cytopenia and the relationship between persistent cytopenia, efficacy, and AEs after anti-CD19 CAR T cell therapy are unknown. Therefore, this study explored whether persistent cytopenia after anti-CD19 CAR T cell therapy in patients with R/R DLBCL can predict therapeutic efficacy and AEs. Thirty-eight patients with R/R DLBCL were enrolled in an anti-CD19 CAR T cell therapy clinical trial. Patients received lymphodepleting chemotherapy with fludarabine and cyclophosphamide before CAR T cell therapy. The degree and duration of cytopenia, clinical response, proportion of CAR T cells, interleukin-6 (IL-6) levels, AEs, and follow-up were observed after therapy. Grades 3-4 persistent cytopenia occurred in 14 patients with R/R DLBCL, who recovered 8-18 weeks after CAR T cell infusion. These patients achieved an objective response rate (ORR) for anti-CD19 CAR T cell therapy. In patients who achieved ORR, the incidence of Grades 3-4 persistent cytopenia was higher in patients with a high tumor load than in those without a high tumor load. The mean peaks of IL-6 and anti-CD19 CAR T cells and the cytokine release syndrome grade in patients with Grades 3-4 persistent cytopenia were higher than those in patients without persistent cytopenia. Anti-CD19 CAR T cells were observed 21 and 28 days after infusion, and patients had Grades 3-4 persistent cytopenia. Progression-free and overall survival were higher in patients with Grades 3-4 persistent cytopenia than in those without cytopenia. Therefore, persistent cytopenia after anti-CD19 CAR T cell therapy in patients with R/R DLBCL can predict therapeutic efficacy and AEs, allowing clinicians to determine the efficiency of CD-19 CAR T cell therapy and the associated AEs.

Long-term analysis of cellular immunity in patients with RRMM treated with CAR-T cell therapy

Chimeric antigen receptor T (CAR-T) cell therapy exhibits remarkable efficacy against refractory or relapsed multiple myeloma (RRMM); however, the immune deficiency following CAR-Ts infusion has not been well studied. In this study, 126 patients who achieved remission post-CAR-Ts infusion were evaluated for cellular immunity. Following lymphodepletion (LD) chemotherapy, the absolute lymphocyte count (ALC) and absolute counts of lymphocyte subsets were significantly lower than baseline at D0. Grade ≥ 3 lymphopenia occurred in 99% of patients within the first 30 days, with most being resolved by 180 days. The median CD4+ T-cell count was consistently below baseline and the lower limit of normal (LLN) levels at follow-up. Conversely, the median CD8+ T-cell count returned to the baseline and LLN levels by D30. The median B-cell count remained lower than baseline level at D60 and returned to baseline and LLN levels at D180. In the first 30 days, 27 (21.4%) patients had 29 infections, with the majority being mild to moderate in severity (21/29; 72.4%). After day 30, 44 (34.9%) patients had 56 infections, including 20 severe infections. One patient died from bacteremia at 3.8 months post-CAR-Ts infusion. In conclusion, most patients with RRMM experienced cellular immune deficiency caused by LD chemotherapy and CAR-Ts infusion. The ALC and most lymphocyte subsets gradually recovered after day 30 of CAR-Ts infusion, except for CD4+ T cells. Some patients experience prolonged CD4+ T-cell immunosuppression without severe infection.

Regulatory T Cells in Atherosclerosis: Is Adoptive Cell Therapy Possible?

Atherosclerosis is an insidious vascular disease with an asymptomatic debut and development over decades. The aetiology and pathogenesis of atherosclerosis are not completely clear. However, chronic inflammation and autoimmune reactions play a significant role in the natural course of atherosclerosis. The pathogenesis of atherosclerosis involves damage to the intima, immune cell recruitment and infiltration of cells such as monocytes/macrophages, neutrophils, and lymphocytes into the inner layer of vessel walls, and the accumulation of lipids, leading to vascular inflammation. The recruited immune cells mainly have a pro-atherogenic effect, whereas CD4+ regulatory T (Treg) cells are another heterogeneous group of cells with opposite functions that suppress the pathogenic immune responses. Present in low numbers in atherosclerotic plaques, Tregs serve a protective role, maintaining immune homeostasis and tolerance by suppressing pro-inflammatory immune cell subsets. Compelling experimental data suggest that various Treg cell-based approaches may be important in the treatment of atherosclerosis. Here we highlight the most recent advances in our understanding of the roles of FOXP3-expressing CD4+ Treg cells in the atherogenic process and discuss potential translational strategies for the treatment of atherosclerosis by Treg manipulation.

Low-dose administration of prednisone has a good effect on the treatment of prolonged hematologic toxicity post-CD19 CAR-T cell therapy

Introduction

Hematologic toxicity (HT) is a joint adverse event after CAR-T cells infusion. Some patients experience prolonged hematologic toxicity (PHT), which is challenging to treat.

Methods

We collected clinical data from patients with relapsed refractory B-ALL treated with CD19 CAR-T cells. Patients with PHT who did not respond to erythropoietin, platelet receptor agonists, transfusion, or G-CSF and eventually received low-dose prednisone therapy were included in the analysis. We retrospectively analyzed the efficacy and safety of low-dose prednisone on PHT.

Results

Among 109 patients treated with CD19 CAR-T cells, 78.9% (86/109) of patients were evaluated as PHT. Of these, 15 patients had persistent hematological toxicity after infusion (12 were grade 3/4 cytopenia, 12 were trilineage cytopenia and 3 were bilineage cytopenia), 2 developed cytopenia without apparent cause after D28. The initial prednisone dose was 0.5 mg/kg/day, and the median response time was 21 days (7-40 days). The recovery rate of blood count was 100%, and the complete recovery rate ranged from 60% to 66.67%. Especially exciting was that HT recurred in 6 patients after stopping prednisone. They were relieved again after the administration of prednisone. The median follow-up time was 14.97 months (4.1-31.2 months). Twelve-month duration of PFS and OS rates were 58.8% (±11.9%) and 64.7% (±11.6%). We did not observe any other side effects of prednisone apart from drug-controllable hyperglycemia and hypertension.

Discussion

We suggest that low-dose prednisone is a beneficial and tolerable therapy for PHT after CAR-T cells. The trials have been registered at www.chictr.org.cn as ChiCTR-ONN-16009862 (November 14, 2016) and ChiCTR1800015164 (March 11, 2018).

Targeting immune checkpoints: how to use natural killer cells for fighting against solid tumors

Natural killer (NK) cells are unique innate immune cells that mediate anti-viral and anti-tumor responses. Thus, they might hold great potential for cancer immunotherapy. NK cell adoptive immunotherapy in humans has shown modest efficacy. In particular, it has failed to demonstrate therapeutic efficiency in the treatment of solid tumors, possibly due in part to the immunosuppressive tumor microenvironment (TME), which reduces NK cell immunotherapy's efficiencies. It is known that immune checkpoints play a prominent role in creating an immunosuppressive TME, leading to NK cell exhaustion and tumor immune escape. Therefore, NK cells must be reversed from their dysfunctional status and increased in their effector roles in order to improve the efficiency of cancer immunotherapy. Blockade of immune checkpoints can not only rescue NK cells from exhaustion but also augment their robust anti-tumor activity. In this review, we discussed immune checkpoint blockade strategies with a focus on chimeric antigen receptor (CAR)-NK cells to redirect NK cells to cancer cells in the treatment of solid tumors.

Efficacy and safety of CD22-specific and CD19/CD22-bispecific CAR-T cell therapy in patients with hematologic malignancies: A systematic review and meta-analysis

Background

CD22 single and CD19/CD22 bispecific targeted chimeric antigen receptor T (CAR-T) cell therapy are promising immunotherapy modalities for the treatment of hematologic malignancies. The aim of this study was to assess the efficacy and safety of CD22 and CD19/CD22 targeted CAR-T cell therapy by summarizing the existing evidence.

Methods

Electronic databases including PubMed, Embase, and Scopus were comprehensively searched from inception up to November 30, 2022. Pooled response rates and minimal residual disease (MRD) negative response rates, cytokine release syndrome (CRS) rates and neurotoxicity rates were calculated. Subgroup analysis was performed based on the type of immunotherapy.

Results

Ten clinical studies including 194 patients with hematologic malignancies were included after a systematical screening of literature. The pooled complete response (CR) rates of CD22 and CD19/CD22 CAR-T cell therapy for relapsed or refractory B-cell lymphoblastic leukemia (B-ALL) were 0.75 (95% CI: 0.60 - 0.88) and 0.87 (95% CI: 0.76 - 0.96). The overall MRD negative response rates of CD22 and CD19/CD22 CAR-T were 0.54 (95% CI: 0.42 - 0.66) and 0.91 (95% CI: 0.47 - 0.88). Pooled CRS rates of CD22 targeted and CD19/CD22 targeted immunotherapy were 0.92 (95% CI: 0.82 - 0.98) and 0.94 (95% CI: 0.82 - 1.00), respectively.

Conclusion

Both CD22 and CD19/CD22 CAR-T immunotherapy demonstrated favorable efficacy and acceptable adverse events in the treatment of hematologic malignancies. Well-designed and large sample-sized clinical trials are warranted.

Multiple CAR-T cell therapy for acute B-cell lymphoblastic leukemia after hematopoietic stem cell transplantation: A case report

B-cell acute lymphoblastic leukemia (B-ALL) is the most common childhood malignancy. The cure rate has reached 90% after conventional chemotherapy and hematopoietic stem cell transplantation (HSCT), but the prognosis of patients with relapsed and refractory (R/R) leukemia is still poor after conventional treatment. Since FDA approved CD19 CAR-T cell (Kymriah) for the treatment of R/R B-ALL, increasing studies have been conducted on CAR-T cells for R/R ALL. Herein, we report the treatment of a patient with ALL who relapsed after allogeneic HSCT, had a complete remission (CR) to murine scFv CD19 CAR-T but relapsed 15 months later. Partial response was achieved after humanized CD19 CAR-T treatment, and the patient finally achieved disease-free survival after sequential CD22 CAR-T treatment. By comparing the treatment results of different CAR-T cells in the same patient, this case suggests that multiple CAR-T therapies are effective and safe in intramedullary and extramedullary recurrence in the same patient, and the expansion of CAR-T cells and the release of inflammatory cytokines are positively correlated with their efficacy. However, further clinical studies with large sample sizes are still needed for further clarification.

Chimeric antigen receptor T-cells targeting IL-1RAP: a promising new cellular immunotherapy to treat acute myeloid leukemia

Background

Acute myeloid leukemia (AML) remains a very difficult disease to cure due to the persistence of leukemic stem cells (LSCs), which are resistant to different lines of chemotherapy and are the basis of refractory/relapsed (R/R) disease in 80% of patients with AML not receiving allogeneic transplantation.

Methods

In this study, we showed that the interleukin-1 receptor accessory protein (IL-1RAP) protein is overexpressed on the cell surface of LSCs in all subtypes of AML and confirmed it as an interesting and promising target in AML compared with the most common potential AML targets, since it is not expressed by the normal hematopoietic stem cell. After establishing the proof of concept for the efficacy of chimeric antigen receptor (CAR) T-cells targeting IL-1RAP in chronic myeloid leukemia, we hypothesized that third-generation IL-1RAP CAR T-cells could eliminate AML LSCs, where the medical need is not covered.

Results

We first demonstrated that IL-1RAP CAR T-cells can be produced from AML T-cells at the time of diagnosis and at relapse. In vitro and in vivo, we showed the effectiveness of IL-1RAP CAR T-cells against AML cell lines expressing different levels of IL-1RAP and the cytotoxicity of autologous IL-1RAP CAR T-cells against primary cells from patients with AML at diagnosis or at relapse. In patient-derived relapsed AML xenograft models, we confirmed that IL-1RAP CAR T-cells are able to circulate in peripheral blood and to migrate in the bone marrow and spleen, are cytotoxic against primary AML cells and increased overall survival.

Conclusion

In conclusion, our preclinical results suggest that IL-1RAP CAR T-based adoptive therapy could be a promising strategy in AML treatment and it warrants the clinical investigation of this CAR T-cell therapy.

CAR-T Cell Therapy in Hematological Malignancies: Current Opportunities and Challenges

Chimeric antigen receptor T (CAR-T) cell therapy represents a major breakthrough in cancer treatment, and it has achieved unprecedented success in hematological malignancies, especially in relapsed/refractory (R/R) B cell malignancies. At present, CD19 and BCMA are the most common targets in CAR-T cell therapy, and numerous novel therapeutic targets are being explored. However, the adverse events related to CAR-T cell therapy might be serious or even life-threatening, such as cytokine release syndrome (CRS), CAR-T-cell-related encephalopathy syndrome (CRES), infections, cytopenia, and CRS-related coagulopathy. In addition, due to antigen escape, the limited CAR-T cell persistence, and immunosuppressive tumor microenvironment, a considerable proportion of patients relapse after CAR-T cell therapy. Thus, in this review, we focus on the progress and challenges of CAR-T cell therapy in hematological malignancies, such as attractive therapeutic targets, CAR-T related toxicities, and resistance to CAR-T cell therapy, and provide some practical recommendations.

The Direct to Consumer Stem Cell Market and the Role of Primary Care Providers in Correcting Misinformation

INTRODUCTION

Direct to consumer stem cell and regenerative interventions (SCRIs) for various medical conditions have increased in popularity due to unmet medical needs and the promise of SCRIs to meet those needs. These interventions may have varying levels of safety and efficacy data and many lack sufficient scientific data to be marketed. The direct to consumer SCRI industry has received significant attention due to potential physical, economic, and emotional harms to patients. Patients may seek the counsel of their primary care providers when considering stem cell therapy for their condition.

METHODS

Here we describe strategies primary care providers can utilize when counseling patients.

RESULTS

Although we recommend constructing these discussions around individual patients' needs, one can utilize a general approach consisting of 4 parts. First, providers should recognize what information the patient is seeking and what is their understanding of stem cell and regenerative medicine. Next, providers should convey evidence-based information at the level of patients understanding so that they are aware of the risks, benefits, and descriptions of possible procedures. Throughout the conversations, attempts should be made to guide patients to a trusted resource that can provide additional information. Finally, providers should make an effort to address misinformation in a way that is nonjudgmental and patient-centered to make the patient feel safe and comfortable.

CONCLUSION

Effectively communicating risk information by primary care providers to patients is important given the harms reported from direct-to-consumer SCRIs. Correcting misinformation remains a priority when discussing SCRI's. Providers should strive to offer patients with additional resources such as the opportunity for consultation with a specialist or a consultation service dedicated to informing patients about regenerative medicine.

CAR Treg: A new approach in the treatment of autoimmune diseases

Regulatory T cells (Tregs) have the role of regulating self-tolerance, and suppressing immune responses. Defects in Treg function and number can lead to in loss of tolerance or autoimmune disease. To treat or control autoimmune diseases, one of the options is to develop immune tolerance for Tregs cell therapy, which includes promotion and activation. Recently, cell-based treatment as a promising approach to increase cells function and number has been developed. Cell therapy by chimeric T antigen receptor (CAR-T) cells has shown significant efficacy in the treatment of leukemia, which has led researchers to use CAR-T cells in other diseases like autoimmune diseases. Here, we describe the existing treatments for autoimmune diseases and the available treatments based on Treg, their benefits and restrictions for implementation in clinical trials. We also discussed potential solutions to overcome these limitations. It seems novel designs of CARs to be new hope for autoimmune diseases and expected to be a potential cure option in a wide array of disease in the future. Therefore, it is very important to address this issue and increase information about it.

Manufacturing T cells in hollow fiber membrane bioreactors changes their programming and enhances their potency

Engineered T cell therapies have revolutionized modern oncology, however processes for manufacturing T cell therapies vary and the impact of manufacturing processes On the cell product is poorly understood. Herein, we have used a commercially available hollow fiber membrane bioreactor (HFMBR) operated in a novel mode to demonstrate that T cells can be engineered with lentiviruses, grown to very high densities, and washed and harvested in a single, small volume bioreactor that is readily amenable to automation. Manufacturing within the HFMBR dramatically changed the programming of the T cells and yielded a product with greater therapeutic potency than T cells produced using the standard manual method. This change in programming was associated with increased resistance to cryopreservation, which is beneficial as T cell products are typically cryopreserved prior to administration to the patient. Transcriptional profiling of the T cells revealed a shift toward a glycolytic metabolism, which may protect cells from oxidative stress offering an explanation for the improved resistance to cryopreservation. This study reveals that the choice of bioreactor fundamentally impacts the engineered T cell product and must be carefully considered. Furthermore, these data challenge the premise that glycolytic metabolism is detrimental to T cell therapies.

Antigen-Specific Regulatory T Cell Therapy in Autoimmune Diseases and Transplantation

Regulatory T (Treg) cells are a heterogenous population of immunosuppressive T cells whose therapeutic potential for the treatment of autoimmune diseases and graft rejection is currently being explored. While clinical trial results thus far support the safety and efficacy of adoptive therapies using polyclonal Treg cells, some studies suggest that antigen-specific Treg cells are more potent in regulating and improving immune tolerance in a disease-specific manner. Hence, several approaches to generate and/or expand antigen-specific Treg cells in vitro or in vivo are currently under investigation. However, antigen-specific Treg cell therapies face additional challenges that require further consideration, including the identification of disease-relevant antigens as well as the in vivo stability and migratory behavior of Treg cells following transfer. In this review, we discuss these approaches and the potential limitations and describe prospective strategies to enhance the efficacy of antigen-specific Treg cell treatments in autoimmunity and transplantation.

Chimeric antigen receptor-engineered natural killer cells for cancer immunotherapy

Natural killer (NK) cells are a critical component of the innate immune system. Chimeric antigen receptors (CARs) re-direct NK cells toward tumor cells carrying corresponding antigens, creating major opportunities in the fight against cancer. CAR NK cells have the potential for use as universal CAR cells without the need for human leukocyte antigen matching or prior exposure to tumor-associated antigens. Exciting data from recent clinical trials have renewed interest in the field of cancer immunotherapy due to the potential of CAR NK cells in the production of "off-the-shelf" anti-cancer immunotherapeutic products. Here, we provide an up-to-date comprehensive overview of the recent advancements in key areas of CAR NK cell research and identify under-investigated research areas. We summarize improvements in CAR design and structure, advantages and disadvantages of using CAR NK cells as an alternative to CAR T cell therapy, and list sources to obtain NK cells. In addition, we provide a list of tumor-associated antigens targeted by CAR NK cells and detail challenges in expanding and transducing NK cells for CAR production. We additionally discuss barriers to effective treatment and suggest solutions to improve CAR NK cell function, proliferation, persistence, therapeutic effectiveness, and safety in solid and liquid tumors.

Function and evolution of the prototypic CD28ζ and 4-1BBζ chimeric antigen receptors

T cells engineered to express chimeric antigen receptors (CARs) specific for CD19 have yielded remarkable clinical outcomes in patients with refractory B-cell malignancies. The first CARs to be approved by the US Food and Drug Administration and the European Medicines Agency are CD19 CARs that comprise either CD28/CD3ζ or 4-1BB/CD3ζ dual-signalling domains. While their efficacy and safety profiles in patients with B-cell malignancies are comparable overall, the functional properties these two CAR designs impart upon engineered T cells differ significantly. Remarkably, alternative costimulatory domains have not, to date, superseded these foundational designs. Rather, recent CAR advances have focused on perfecting the original CD28- and 4-1BB-based CD19 CARs by calibrating strength of activation, pre-empting T-cell exhaustion and increasing the functional persistence of CAR T cells. This article reviews the essential biological properties of these first-in-class prototypes and their recent evolution.

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CD19 chimeric antigen receptor (CAR) therapy has shown remarkable success against B-cell malignancies.

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The prototypic CD19 CARs comprise either CD28/CD3ζ or 4-1BB/CD3ζ signalling domains.

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Both CD19 CARs yield similar efficacy but impart distinct T-cell functionalities.

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Novel CAR designs aim to enhance the persistence or effector potency of T cells.

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Genome editing averts variegated CAR expression and sustains T-cell function.

Side-effect management of chimeric antigen receptor (CAR) T-cell therapy

Chimeric antigen receptor (CAR) T cells directed against the B-cell marker CD19 are currently changing the landscape for treatment of patients with refractory and/or relapsed B-cell malignancies. Due to the nature of CAR T cells as living drugs, they display a unique toxicity profile. As CAR T-cell therapy is extending towards other diseases and being more broadly employed in hematology and oncology, optimal management strategies of side-effects associated with CAR T-cell therapy are of high relevance. Cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and cytopenias constitute challenges in the treatment of patients with CAR T cells. This review summarizes the current understanding of CAR T-cell toxicity and its management.

Tailoring precision immunotherapy: coming to a clinic soon?

Cell-based and antibody-based cancer immunotherapies have been widely tested across increasing numbers of cancers with an unprecedented number of successful practice-changing immunotherapy clinical trials, achieving significant survival outcomes and, characteristically, some very long-term survivors. Still, a sizeable proportion of patients, especially with solid tumours, do not benefit from immunotherapy. Here, we summarise key literature on immunotherapy biomarkers and resistance mechanisms and discuss potential strategies to overcome such resistance to improve patient outcomes. The ever-expanding understanding of the tumour-immune interaction and the tumour microenvironment allows a real opportunity to identify predictive biomarkers and tailor immune-based therapies, including designing rational combination drugs to enhance clinical outcomes, and to identify patients most likely to benefit from immunotherapy. Where there has never been a precision chemotherapy clinic in the last 70 years since its inception, even with no shortage of trying, the hope and evolution of a functional precision immunotherapy cancer clinic is a much more likely reality.

The Immunological Basis of Liver Allograft Rejection

Liver allograft rejection remains a significant cause of morbidity and graft failure in liver transplant recipients. Rejection is caused by the recognition of non-self donor alloantigens by recipient T-cells. Antigen recognition results in proliferation and activation of T-cells in lymphoid tissue before migration to the allograft. Activated T-cells have a variety of effector mechanisms including direct T-cell mediated damage to bile ducts, endothelium and hepatocytes and indirect effects through cytokine production and recruitment of tissue-destructive inflammatory cells. These effects explain the histological appearances of typical acute T-cell mediated rejection. In addition, donor specific antibodies, most typically against HLA antigens, may give rise to antibody-mediated rejection causing damage to the allograft primarily through endothelial injury. However, as an immune-privileged site there are several mechanisms in the liver capable of overcoming rejection and promoting tolerance to the graft, particularly in the context of recruitment of regulatory T-cells and promotors of an immunosuppressive environment. Indeed, around 20% of transplant recipients can be successfully weaned from immunosuppression. Hence, the host immunological response to the liver allograft is best regarded as a balance between rejection-promoting and tolerance-promoting factors. Understanding this balance provides insight into potential mechanisms for novel anti-rejection therapies.

Immune reconstitution and associated infections following axicabtagene ciloleucel in relapsed or refractory large B-cell lymphoma

CD19 CAR T-cell therapy with axicabtagene ciloleucel (axi-cel) for relapsed or refractory (R/R) large B cell lymphoma (LBCL) may lead to durable remissions, however, prolonged cytopenias and infections may occur. In this single center retrospective study of 85 patients, we characterized immune reconstitution and infections for patients remaining in remission after axi-cel for LBCL. Prolonged cytopenias (those occurring at or after day 30 following infusion) were common with >= grade 3 neutropenia seen in 21/70 (30-0%) patients at day 30 and persisting in 3/31 (9-7%) patients at 1 year. B cells were undetectable in 30/34 (88-2%) patients at day 30, but were detected in 11/19 (57-9%) at 1 year. Median IgG levels reached a nadir at day 180. By contrast, CD4 T cells decreased from baseline and were persistently low with a median CD4 count of 155 cells/μl at 1 year after axi-cel (n=19, range 33 - 269). In total, 23/85 (27-1%) patients received IVIG after axi-cel, and 34/85 (40-0%) received G-CSF. Infections in the first 30 days occurred in 31/85 (36-5%) patients, of which 11/85 (12-9%) required intravenous antibiotics or hospitalization ("severe") and were associated with cytokine release syndrome (CRS), neurotoxicity, tocilizumab use, corticosteroid use, and bridging therapy on univariate analyses. After day 30, 7 severe infections occurred, with no late deaths due to infection. Prolonged cytopenias are common following axi-cel therapy for LBCL and typically recover with time. Most patients experience profound and prolonged CD4 T cell immunosuppression without severe infection.

QTY Code-designed Water-soluble Fc-fusion Cytokine Receptors Bind to their Respective Ligands

Cytokine release syndrome (CRS), or ‘cytokine storm’, is the leading side effect during chimeric antigen receptor (CAR)-T therapy that is potentially life-threatening. It also plays a critical role in viral infections such as Coronavirus Disease 2019 (COVID-19). Therefore, efficient removal of excessive cytokines is essential for treatment. We previously reported a novel protein modification tool called the QTY code, through which hydrophobic amino acids Leu, Ile, Val and Phe are replaced by Gln (Q), Thr (T) and Tyr (Y). Thus, the functional detergent-free equivalents of membrane proteins can be designed. Here, we report the application of the QTY code on six variants of cytokine receptors, including interleukin receptors IL4Rα and IL10Rα, chemokine receptors CCR9 and CXCR2, as well as interferon receptors IFNγR1 and IFNλR1. QTY-variant cytokine receptors exhibit physiological properties similar to those of native receptors without the presence of hydrophobic segments. The receptors were fused to the Fc region of immunoglobulin G (IgG) protein to form an antibody-like structure. These QTY code-designed Fc-fusion receptors were expressed in Escherichia coli and purified. The resulting water-soluble fusion receptors bind to their respective ligands with K_d values affinity similar to isolated native receptors. Our cytokine receptor–Fc-fusion proteins potentially serve as an antibody-like decoy to dampen the excessive cytokine levels associated with CRS and COVID-19 infection.

Immunotherapy Deriving from CAR-T Cell Treatment in Autoimmune Diseases

Chimeric antigen receptor T (CAR-T) cells are T cells engineered to express specific synthetic antigen receptors that can recognize antigens expressed by tumor cells, which after the binding of these antigens to the receptors are eliminated, and have been adopted to treat several kinds of malignancies. Autoimmune diseases (AIDs), a class of chronic disease conditions, can be broadly separated into autoantibody-mediated and T cell-mediated diseases. Treatments for AIDs are focused on restoring immune tolerance. However, current treatments have little effect on immune tolerance inverse; even the molecular target biologics like anti-TNFα inhibitors can only mildly restore immune balance. By using the idea of CAR-T cell treatment in tumors, CAR-T cell-derived immunotherapies, chimeric autoantibody receptor T (CAAR-T) cells, and CAR regulatory T (CAR-T) cells bring new hope of treatment choice for AIDs.

Antitumor effects of immunity-enhancing traditional Chinese medicine

Traditional Chinese Medicine (TCM) has been traditionally used to treat patients with cancers in China. It not only alleviates the symptoms of tumor patients and improves their quality of life, but also controls the size of tumors and prolongs the survival of tumor patients. While some herbs of TCM may exert therapeutic effects by directly targeting cancer cells or reducing side effects caused by antitumor drugs, others can control tumor growth and metastasis via enhancing antitumor immunity. In particular, TCM can exert antitumor effects by upregulating immune responses even in immunosuppressive tumor microenvironment. For instance, it reduces the number of M2-type macrophages and Treg cells in the tumor tissue. Although extensive reviews on directly killing cancer cells by TCM have been conducted, a review of anticancer activity of TCM solely based on its immunity-enhancing capacity is unusual. This review will summarize research progress of antitumor TCM that regulates the immune system, including both innate immunity, such as macrophages, dendritic cells, natural killer cells and MDSCs, and adaptive immunity, including CD4⁺/CD8⁺ T lymphocytes, regulatory T cells (Tregs) and B cells. As cancer immunotherapy has recently achieved certain success, it is expected that the clinical applications of immunity-enhancing TCM or traditional medicine for treating various cancer patients will be expanded. Further studies on the mechanisms by which TCM regulates immunity will provide new insights into how TCM controls tumor growth and metastasis, and may help improve its therapeutic effects on various cancers in clinic.

Chimeric Antigen Receptor-Engineered T-Cells - A New Way and Era for Lymphoma Treatment

BACKGROUND

Patients with refractory or relapsed diffuse large B-cell lymphoma have a poor prognosis with the current standard of care.

OBJECTIVE

Chimeric Antigen Receptor T-cells (CAR T-cells) are functionally reprogrammed lymphocytes, which are able to recognize and kill tumor cells. The aim of this study is to make progress in this area.

METHODS

A mini-review was achieved using the articles published in Web of Science and PubMed in the last year and the new patents were made in this field.

RESULTS

The responses to CAR T-cell products axicabtagene ciloleucel and tisagenlecleucel are promising; the objective response rate can reach up to 83%, and the complete response rate ranges between 40 and 58%. About half of the patients may have serious side effects, such as cytokine release syndrome and neurotoxicity. Current and future developments include the improvement of CAR T-cell expansion and polyfunctionality, the combined use of CAR T-cells with a fusion protein between interferon and an anti-CD20 monoclonal antibody, with checkpoint inhibitors or small molecule sensitizers that have apoptotic-regulatory effects. Furthermore, the use of IL-12-expressing CAR T-cells, an improved technology for the production of CAR T-cells based on targeted nucleases, the widespread use of allogeneic CAR T-cells or universal CAR T-cells obtained from genetically engineered healthy donor T-cells are future developments actively considered.

CONCLUSION

CAR T-cell therapy significantly improved the outcome of patients with relapsed or refractory diffuse large B-cell lymphoma. The advances in CAR T-cells production technology will improve the results and enable the expansion of this new immunotherapy.

Future prospects for CD8+ regulatory T cells in immune tolerance

CD8⁺ Tregs have been long described and significant progresses have been made about their phenotype, their functional mechanisms, and their suppressive ability compared to conventional CD4⁺ Tregs. They are now at the dawn of their clinical use. In this review, we will summarize their phenotypic characteristics, their mechanisms of action, the similarities, differences and synergies between CD8⁺ and CD4⁺ Tregs, and we will discuss the biology, development and induction of CD8⁺ Tregs, their manufacturing for clinical use, considering open questions/uncertainties and future technically accessible improvements notably through genetic modifications.

CD22 CAR T-cell therapy in refractory or relapsed B acute lymphoblastic leukemia

Despite worldwide promising clinical outcome of CD19 CAR-T therapy, relapse after this therapy is associated with poor prognosis and has become an urgent problem to be solved. We conducted a CD22 CAR T-cell therapy in 34 relapsed or refractory (r/r) B-ALL pediatric and adult patients who failed from previous CD19 CAR T-cell therapy. Complete remission (CR) or CR with incomplete count recovery (CRi) was achieved in 24 of 30 patients (80%) that could be evaluated on day 30 after infusion, which accounted for 70.5% of all 34 enrolled patients. Most patients only experienced mild cytokine-release syndrome and neurotoxicity. Seven CR patients received no further treatment, and 3 of them remained in remission at 6, 6.6, and 14 months after infusion. Eleven CR patients were promptly bridged to transplantation, and 8 of them remained in remission at 4.6 to 13.3 months after transplantation, resulted in 1-year leukemia-free survival rate of 71.6% (95% CI, 44.2-99.0). CD22 antigen loss or mutation was not observed to be associated with relapsed patients. Our study demonstrated that our CD22 CAR T-cells was highly effective in inducing remission in r/r B-ALL patients, and also provided a precious window for subsequent transplantation to achieve durable remission.

Engineering antigen-specific NK cell lines against the melanoma-associated antigen tyrosinase via TCR gene transfer

Introduction of Chimeric Antigen Receptors to NK cells has so far been the main practical method for targeting NK cells to specific surface antigens. In contrast, T cell receptor (TCR) gene delivery can supply large populations of cytotoxic T-lymphocytes (CTL) targeted against intracellular antigens. However, a major barrier in the development of safe CTL-TCR therapies exists, wherein the mispairing of endogenous and genetically transferred TCR subunits leads to formation of TCRs with off-target specificity. To overcome this and enable specific intracellular antigen targeting, we have tested the use of NK cells for TCR gene transfer to human cells. Our results show that ectopic expression of TCR α/β chains, along with CD3 subunits, enables the functional expression of an antigen-specific TCR complex on NK cell lines NK-92 and YTS, demonstrated by using a TCR against the HLA-A2-restricted tyrosinase-derived melanoma epitope, Tyr_368-377 . Most importantly, the introduction of a TCR complex to NK cell lines enables MHC-restricted, antigen-specific killing of tumor cells both in vitro and in vivo. Targeting of NK cells via TCR gene delivery stands out as a novel tool in the field of adoptive immunotherapy which can also overcome the major hurdle of "mispairing" in TCR gene therapy.

Effective Targeting of TAG72+ Peritoneal Ovarian Tumors via Regional Delivery of CAR-Engineered T Cells

Impressive clinical efficacy of chimeric antigen receptor (CAR)-engineered T cell therapy for hematological malignancies have prompted significant efforts in achieving similar responses in solid tumors. The lack of truly restricted and uniform expression of tumor-associated antigens, as well as limited T cell persistence and/or tumor trafficking pose major challenges for successful translation of CAR T cell therapy in solid tumors. Recent studies have demonstrated that aberrantly glycosylated cell surface proteins on tumor cells are amenable CAR targets. Tumor-associated glycoprotein 72 (TAG72) antigen is the sialyl-Tn found on multiple O-glycoproteins expressed at high levels on the surface of several cancer types, including ovarian cancer. Here, we developed a humanized TAG72-specific CAR containing a 4-1BB intracellular co-stimulatory signaling domain (TAG72-BBζ). TAG72-BBζ CAR T cells showed potent antigen-dependent cytotoxicity and cytokine production against multiple TAG72⁺ ovarian cancer cell lines and patient-derived ovarian cancer ascites. Using in vivo xenograft models of peritoneal ovarian tumors, regional intraperitoneal delivery of TAG72-BBζ CAR T cells significantly reduced tumor growth, extended overall survival of mice, and was further improved with repeat infusions of CAR T cells. However, reduced TAG72 expression was observed in early recurring tumors, which coincided with a lack of T cell persistence. Taken together, we demonstrate efficacy with TAG72-CAR T cells in ovarian cancer, warranting further investigations as a CAR T cell therapeutic strategy for this disease.

New therapeutic opportunities from dissecting the pre-B leukemia bone marrow microenvironment

The microenvironments of leukemia and cancer are critical for multiple stages of malignancies, and they are an attractive therapeutic target. While skeletal abnormalities are commonly seen in children with acute lymphoblastic leukemia (ALL) prior to initiating osteotoxic therapy, little is known about the alterations to the bone marrow microenvironment during leukemogenesis. Therefore, in this study, we focused on the development of precursor-B cell ALL (pre-B ALL) in an immunocompetent BCR-ABL1+ model. Here we show that hematopoiesis was perturbed, B lymphopoiesis was impaired, collagen production was reduced, and the number of osteoblastic cells was decreased in the bone marrow microenvironment. As previously found in children with ALL, the leukemia-bearing mice exhibited severe bone loss during leukemogenesis. Leukemia cells produced high levels of receptor activator of nuclear factor κB ligand (RANKL), sufficient to cause osteoclast-mediated bone resorption. In vivo administration of zoledronic acid rescued leukemia-induced bone loss, reduced disease burden and prolonged survival in leukemia-bearing mice. Taken together, we provide evidence that targeting leukemia-induced bone loss is a therapeutic strategy for pre-B ALL.

Chimeric Antigen Receptor (CAR) Treg: A Promising Approach to Inducing Immunological Tolerance

Cellular therapies with polyclonal regulatory T-cells (Tregs) in transplantation and autoimmune diseases have been carried out in both animal models and clinical trials. However, The use of large numbers of polyclonal Tregs with unknown antigen specificities has led to unwanted effects, such as systemic immunosuppression, which can be avoided via utilization of antigen-specific Tregs. Antigen-specific Tregs are also more potent in suppression than polyclonal ones. Although antigen-specific Tregs can be induced in vitro, these iTregs are usually contaminated with effector T cells during in vitro expansion. Fortunately, Tregs can be efficiently engineered with a predetermined antigen-specificity via transfection of viral vectors encoding specific T cell receptors (TCRs) or chimeric antigen receptors (CARs). Compared to Tregs engineered with TCRs (TCR-Tregs), CAR-modified Tregs (CAR-Tregs) engineered in a non-MHC restricted manner have the advantage of widespread applications, especially in transplantation and autoimmunity. CAR-Tregs also are less dependent on IL-2 than are TCR-Tregs. CAR-Tregs are promising given that they maintain stable phenotypes and functions, preferentially migrate to target sites, and exert more potent and specific immunosuppression than do polyclonal Tregs. However, there are some major hurdles that must be overcome before CAR-Tregs can be used in clinic. It is known that treatments with anti-tumor CAR-T cells cause side effects due to cytokine “storm” and neuronal cytotoxicity. It is unclear whether CAR-Tregs would also induce these adverse reactions. Moreover, antibodies specific for self- or allo-antigens must be characterized to construct antigen-specific CAR-Tregs. Selection of antigens targeted by CARs and development of specific antibodies are difficult in some disease models. Finally, CAR-Treg exhaustion may limit their efficacy in immunosuppression. Recently, innovative CAR-Treg therapies in animal models of transplantation and autoimmune diseases have been reported. In this mini-review, we have summarized recent progress of CAR-Tregs and discussed their potential applications for induction of immunological tolerance.

Cancer Immunotherapy – The Target is Precisely on The Cancer and Also Not

In recent years, the impressive number of cancer immunotherapy drugs approved has been unprecedented—building on over a century of understanding on how the immune system combats cancer, and how cancer evades it. Leading the charge are the immune checkpoint inhibitor monoclonal antibodies, and adoptive cell therapy with chimeric-antigen-receptor (CAR)-T cell therapy. These breakthrough therapies have led to improved survival in patients with many advanced cancers. Some of  the clinical outcomes have been striking, and may even be potentially curative in some terminal cancer patients. While immune checkpoint inhibitors work by blocking regulatory immune checkpoint signals between cancer and the immune cells to awaken an effective anticancer immunity, CAR-T cell therapy targets specific molecules on cancer cells. Tumour antigens as cancer targets take many forms and may not necessarily be proteins related to known functional cellular mechanisms. The convergence of cutting edge omics, bioinformatics, protein synthesis, immunobiology and immunotherapy have led to novel, potentially highly effective cancer targeting against neoantigens, hence reviving the quest for anticancer vaccines. Early clinical trials of  neoantigen vaccines have provided proof-of-principle efficacy, especially in melanoma patients. Combinations of immunotherapies through rational design are underway aiming to further improve clinical outcomes. Moving forward, cancer immunotherapy will gain even more momentum from the discovery of more cancer targets—both on the cancer itself and in the tumour microenvironment as well as the identification of biomarkers of treatment resistance and efficacy. Key words: Checkpoint inhibitor, Microenvironment, Neoantigens, Vaccine

The Impact of Advanced Patient Age on Mortality after Allogeneic Hematopoietic Cell Transplantation for Non-Hodgkin Lymphoma: A Retrospective Study by the European Society for Blood and Marrow Transplantation Lymphoma Working Party

More than 60% of patients with non-Hodgkin lymphoma (NHL) are age >60 years at presentation. The purpose of this study was to compare the potential risks and benefits of allogeneic hematopoietic cell transplantation (alloHCT) in elderly patients with NHL with younger patients in a large sample, also taking into account comorbidity information. All patients age ≥18 years who had undergone alloHCT from a matched sibling or unrelated donor for NHL between 2003 and 2013 and were registered with the European Society for Blood and Marrow Transplantation were eligible for the study. The primary study endpoint was 1-year nonrelapse mortality (NRM). A total of 3919 patients were eligible and were categorized by age: young (Y), 18 to 50 y (n = 1772); middle age (MA), 51 to 65 y (n = 1967); or old (O), 66 to 77 y (n = 180). Follicular lymphoma was present in 37% of the patients; diffuse large B cell lymphoma, in 30%; mantle cell lymphoma, in 21%, and peripheral T cell lymphoma, in 11%. At the time of alloHCT, 85% of the patients were chemosensitive and 15% were chemorefractory. With a median follow-up of 4.5 years in survivors, NRM at 1 year was 13% for the Y group. 20% for the MA group, and 33% for the O group (P <.001), whereas relapse incidence and overall survival (OS) at 3 years in the 3 groups were 30%, 31%, and 28% (P = .355) and 60%, 54%, and 38% (P <.001), respectively. Multivariable adjustment for confounders, including sex, NHL subset, time from diagnosis, chemosensitivity, donor, and conditioning, confirmed older age as a significant predictor for NRM and OS, but not for relapse risk. Although comorbidity was a significant predictor of NRM in a subset analysis restricted to the 979 patients with comorbidity information available, age retained its significant impact on NRM. In conclusion, our data show that alloHCT in patients age >65 y provides similar NHL control as seen in younger patients but is associated with a higher NRM that is not fully explained by comorbidity. Thus, although alloHCT is feasible and effective in very old patients, the increased NRM risk must be taken into account when assessing the indication for alloHCT for NHL in this age group.

Axicabtagene ciloleucel (KTE-C19), an anti-CD19 CAR T therapy for the treatment of relapsed/refractory aggressive B-cell non-Hodgkin's lymphoma

Adoptive T-cell immunotherapy is a rapidly growing field and is shifting the paradigm of clinical cancer treatment. Axicabtagene ciloleucel (axi-cel) is an anti-CD19 chimeric antigen receptor T-cell therapy that was initially developed at the National Cancer Institute and has recently been commercially approved by the US Food and Drug Administration for relapsed or refractory aggressive non-Hodgkin’s lymphomas including diffuse large B-cell lymphoma and its variants. The ZUMA-1 Phase I and II clinical trials formed the basis of the US Food and Drug Administration approval of this product, and we discuss the particulars of the clinical trials and the pharmacology of axi-cel. In addition, we review the CD19 chimeric antigen receptor T-specific toxicities of cytokine release syndrome and neurotoxicity, which remain the challenges to the safe delivery of this important therapy for aggressive B-cell lymphomas with poor prognosis.

Acute myeloid leukemia chimeric antigen receptor T-cell immunotherapy: how far up the road have we traveled?

Chemotherapy resistance and relapse remain significant sources of mortality for children and adults with acute myeloid leukemia (AML). Further intensification of conventional cytotoxic chemotherapy is likely not feasible due to the severity of acute and long-term side effects upon normal tissues commonly induced by these drugs. Successful development and implementation of new precision medicine treatment approaches for patients with AML, which may improve leukemia remission and diminish toxicity, is thus a major priority. Tumor antigen-redirected chimeric antigen receptor (CAR) T-cell immunotherapies have induced remarkable responses in patients with relapsed or chemorefractory B-lymphoblastic leukemia, and similar strategies are now under early clinical study in adults with relapsed/refractory AML. However, potential on target/off tumor toxicity of AML CAR T-cell immunotherapies, notably aplasia of normal myeloid cells, may limit broader implementation of such approaches. Careful selection of optimal target antigens, consideration of toxicity mitigation strategies, and development of methodologies to circumvent potential CAR T-cell resistance are essential for successful implementation of cellular immunotherapies for patients with high-risk AML.

Stromal cells in breast cancer as a potential therapeutic target

Breast cancer in the United States is the second most commonly diagnosed cancer in women. About 1 in 8 women will develop invasive breast cancer over the course of her lifetime and breast cancer remains the second leading cause of cancer-related death. In pursuit of novel therapeutic strategies, researchers have examined the tumor microenvironment as a potential anti-cancer target. In addition to neoplastic cells, the tumor microenvironment is composed of several critical normal cell types, including fibroblasts, vascular and lymph endothelial cells, osteoclasts, adipocytes, and immune cells. These cells have important roles in healthy tissue stasis, which frequently are altered in tumors. Indeed, tumor-associated stromal cells often contribute to tumorigenesis, tumor progression, and metastasis. Consequently, these host cells may serve as a possible target in anti-tumor and anti-metastatic therapeutic strategies. Targeting the tumor associated host cells offers the benefit that such cells do not mutate and develop resistance in response to treatment, a major cause of failure in cancer therapeutics targeting neoplastic cells. This review discusses the role of host cells in the tumor microenvironment during tumorigenesis, progression, and metastasis, and provides an overview of recent developments in targeting these cell populations to enhance cancer therapy efficacy.

Arthritis of large joints shown as a rare clinical feature of cytokine release syndrome after chimeric antigen receptor T cell therapy: A case report

RATIONALE

Chimeric antigen receptor (CAR)-T cell therapy is a novel type of therapy that is being used in an increasing number of patients with acute lymphoblastic leukemia (ALL). Cytokine release syndrome (CRS) is the most common complication following CAR-T treatment, but the current understanding of the clinical manifestations and pathogenesis of CRS is still limited.

PATIENT CONCERNS

A 34-year-old male patient was diagnosed with ALL in June 2015. Complete remission (CR) was achieved after induction chemotherapy. The patient received 8 cycles of consolidation chemotherapy to maintain CR. In May 2017, the patient had recurrent ALL. Induction chemotherapy was given again, but without remission. In October 2017, CAR-T cell therapy was given. On October 14, the patient was pretreated with an FC regimen (fludarabine phosphate 50 mg qd on days 1-3; cyclophosphamide 0.4 g qd on days 1-3). CAR-T cells were infused on October 19 and October 20, with the number of infused cells at 2 × 10/kg and 1 × 10/kg, respectively. On October 25, the patient had a high fever, swelling, and pain in the large joints of the limbs, and joint effusion.

DIAGNOSIS

This patient was diagnosed with relapsed ALL, and he developed CRS after CAR-T therapy.

INTERVENTIONS

Tacilizumab (400 mg) was infused after CRS was diagnosed, and another dose of tacilizumab (240 mg) was given 6 days later. The pain was also treated with an analgesic drug. Methylprednisolone (1 mg/kg) was given to treat arthritis of the large joints.

OUTCOMES

The patient's temperature was back to normal within 1 hour following the treatment of tacilizumab, but the pain in the large joints was progressively aggravated. The joint swelling and pain were obviously alleviated after the treatment of methylprednisolone, and the joint mobility was gradually recovered.

LESSONS

CRS after CAR-T therapy can manifest as a high fever with swelling and pain in the large joints of the limbs, similar to rheumatoid arthritis. Tocilizumab can lower the body temperature, but it has no significant effect on arthritis. Glucocorticoids can rapidly alleviate joint swelling and pain.

Naturally Occurring Canine Melanoma as a Predictive Comparative Oncology Model for Human Mucosal and Other Triple Wild-Type Melanomas

Melanoma remains mostly an untreatable fatal disease despite advances in decoding cancer genomics and developing new therapeutic modalities. Progress in patient care would benefit from additional predictive models germane for human disease mechanisms, tumor heterogeneity, and therapeutic responses. Toward this aim, this review documents comparative aspects of human and naturally occurring canine melanomas. Clinical presentation, pathology, therapies, and genetic alterations are highlighted in the context of current basic and translational research in comparative oncology. Somewhat distinct from sun exposure-related human cutaneous melanomas, there is growing evidence that a variety of gene copy number alterations and protein structure/function mutations play roles in canine melanomas, in circumstances more analogous to human mucosal melanomas and to some extent other melanomas with murine sarcoma viral oncogene homolog B (BRAF), Neuroblastoma RAS Viral (V-Ras) Oncogene Homolog (NRAS), and neurofibromin 1 tumor suppressor NF1 triple wild-type genotype. Gaps in canine genome annotation, as well as an insufficient number and depth of sequences covered, remain considerable barriers to progress and should be collectively addressed. Preclinical approaches can be designed to include canine clinical trials addressing immune modulation as well as combined-targeted inhibition of Rat Sarcoma Superfamily/Mitogen-activated protein kinase (RAS/MAPK) and/or Phosphatidylinositol-3-Kinase/Protein Kinase B/Mammalian target of rapamycin (PI3K/AKT/mTOR) signal transduction, pathways frequently activated in both human and canine melanomas. Future investment should be aimed towards improving understanding of canine melanoma as a predictive preclinical surrogate for human melanoma and for mutually benefiting these uniquely co-dependent species.

New developments in immunotherapy for lymphoma

The development of immunotherapies for lymphoma has undergone a revolutionary evolution over the past decades. Since the advent of rituximab as the first successful immunotherapy for B-cell non-Hodgkin lymphoma over two decades ago, a plethora of new immunotherapeutic approaches to treat lymphoma has ensued. Four of the most exciting classes of immunotherapies include: chimeric antigen receptor T-cells, bispecific antibodies, immune checkpoint inhibitors, and vaccines. However, with addition of these novel therapies the appropriate timing of treatment, optimal patient population, duration of therapy, toxicity, and cost must be considered. In this review, we describe the most-promising immunotherapeutic approaches for the treatment of lymphoma in clinical development, specifically focusing on clinical trials performed to date and strategies for improvement.

Bringing Induced Pluripotent Stem Cell Technology to the Bedside

Induced pluripotent stem cells (iPSCs) describe somatic cells that have been reprogrammed to the pluripotent state. From a scientific perspective, their discovery has provided a molecular roadmap for turning on and off cell identities, effectively allowing any cell type to have its identity changed into any other cell type. They also act as a human model for understanding the development of every cell and organ in the body. In addition, because they can be prepared from patients, iPSCs offer a unique human model for studying disease development, including many diseases that are generally diagnosed at a late stage of their development. These models have provided new insights on the pathogenesis and new targets to prevent or reverse the disease development process. Indeed, clinical studies on compounds based on drug screening hits in human iPSC disease models have begun. Because of their proliferation and differentiation capacity, iPSCs can also be used to prepare cells for transplantations, and related clinical studies using iPSC-based cell therapies are ongoing. The combination of iPSCs with other technologies or therapeutic strategies is expected to expand their medical benefits. In this review, we consider medical accomplishments based on iPSC research and future ones that can be anticipated.