Hematopoietic stem cells promote the expansion and function of adoptively transferred antitumor CD8 T cells

Prognostic differences between carmustine, etoposide, cytarabine and melphalan (BEAM) and carmustine, etoposide, cytarabine, melphalan and fludarabine (BEAMF) regimens before autologous stem cell transplantation plus chimeric antigen receptor T therapy in patients with refractory/relapsed B-cell non-Hodgkin-lymphoma

BACKGROUND AIMS

The combination therapy of autologous hematopoietic stem cell transplantation (ASCT) and chimeric antigen receptor T-cell (CART) therapy has been employed to improve outcomes for relapsed or refractory (R/R) B-cell non-Hodgkin-lymphoma (B-NHL). The widely used conditioning regimen before ASCT plus CART therapy reported in the literature was carmustine, etoposide, cytarabine and melphalan (BEAM). However, whether adding fludarabine to the BEAM regimen (BEAMF) can improve the survival of patients with R/R B-NHL remains unknown.

METHODS

In total, 39 and 19 patients with R/R B-NHL were enrolled to compare clinical outcomes in the BEAM and BEAMF regimens before ASCT plus CD19/22 CART therapy, respectively.

RESULTS

The objective response (OR) rates at 3 months to BEAM and BEAMF regimens before ASCT plus CD19/22 CART therapy were 71.8% and 94.7%, respectively (P = 0.093). The BEAMF regimen showed a trend towards a superior duration of response compared with the BEAM regimen (P = 0.09). After a median follow-up of 28 months (range: 0.93-51.9 months), the BEAMF regimen demonstrated superior 2-year progression-free survival (PFS) (89.5% versus 63.9%; P = 0.048) and 2-year overall survival (OS) (100% vs 77.3%; P = 0.035) compared with the BEAM regimen. In the multivariable Cox regression analysis, OR at month 3 (responders) was remarkably correlated with better OS (hazard ratio: 0.112, P = 0.005) compared with OR (non-responders).

CONCLUSIONS

For patients with R/R B-NHL, the BEAMF regimen before ASCT plus CD19/22 CART therapy was correlated with superior PFS and OS than the BEAM regimen, and the BEAMF regimen is a promising alternative conditioning regimen for ASCT plus CAR-T therapy.

Adverse Reactions in Relapsed/Refractory B-Cell Lymphoma Administered with Chimeric Antigen Receptor T Cell Alone or in Combination with Autologous Stem Cell Transplantation

(1) Background: The combination of CAR-T with ASCT has been observed to enhance the efficacy of CAR-T cell therapy. However, the impact of this combination on adverse reactions is still uncertain. (2) Methods: Between January 2019 and February 2023, 292 patients diagnosed with r/r B-cell lymphoma received either CAR-T therapy alone or in combination with ASCT at our institution. We evaluated the incidence of CRS and CRES and utilized a logistic regression model to identify factors contributing to severe CRS (grade 3-4) and CRES (grade 3-4). (3) Results: The overall incidence of CRS and CRES was 78.9% and 8.2% in 147 patients receiving CAR-T alone, and 95.9% and 15.2% in 145 patients receiving CAR-T combined with ASCT, respectively. The incidence of overall CRS (p < 0.0001) and mild CRS (grade 1-2) (p = 0.021) was elevated in the ASCT combined with CAR-T group. No significant difference was observed in severe CRS and CRES between the groups. Among the 26 cases of lymphoma involving the central nervous system (CNS), 96.2% (25/26) developed CRS (15.4% grade 3-4), and 34.6% (9/26) manifested CRES (7.7% grade 3-4). Female patients had a lower incidence of severe CRS but a higher incidence of severe CRES. Lymphomas with CNS involvement demonstrated a higher risk of CRES compared to those without central involvement. (4) Conclusions: The combination of ASCT with CAR-T demonstrated a preferable option in r/r B-cell lymphoma without an increased incidence of severe CRS and CRES.

Combinational therapy of CAR T-cell and HDT/ASCT demonstrates impressive clinical efficacy and improved CAR T-cell behavior in relapsed/refractory large B-cell lymphoma

BACKGROUND

Approximately two-thirds of patients with relapsed or refractory large B-cell lymphoma (R/R LBCL) do not respond to or relapse after anti-CD19 chimeric antigen receptor T (CAR T)-cell therapy, leading to poor outcomes. Previous studies have suggested that intensified lymphodepletion and hematological stem cell infusion can promote adoptively transferred T-cell expansion, enhancing antitumor effects. Therefore, we conducted a phase I/II clinical trial in which CNCT19 (an anti-CD19 CAR T-cell) was administered after myeloablative high-dose chemotherapy and autologous stem cell transplantation (HDT/ASCT) in patients with R/R LBCL.

METHODS

Transplant-eligible patients with LBCL who were refractory to first-line immunochemotherapy or experiencing R/R status after salvage chemotherapy were enrolled. The study aimed to evaluate the safety and efficacy of this combinational therapy. Additionally, frozen peripheral blood mononuclear cell samples from this trial and CNCT19 monotherapy studies for R/R LBCL were used to evaluate the impact of the combination therapy on the in vivo behavior of CNCT19 cells.

RESULTS

A total of 25 patients with R/R LBCL were enrolled in this study. The overall response and complete response rates were 92.0% and 72.0%, respectively. The 2-year progression-free survival rate was 62.3%, and the overall survival was 68.5% after a median follow-up of 27.0 months. No unexpected toxicities were observed. All cases of cytokine release syndrome were of low grade. Two cases (8%) experienced grade 3 or higher CAR T-cell-related encephalopathy syndrome. The comparison of CNCT19 in vivo behavior showed that patients in the combinational therapy group exhibited enhanced in vivo expansion of CNCT19 cells and reduced long-term exhaustion formation, as opposed to those receiving CNCT19 monotherapy.

CONCLUSIONS

The combinational therapy of HDT/ASCT and CNCT19 demonstrates impressive efficacy, improved CNCT19 behavior, and a favorable safety profile.

TRIAL REGISTRATION NUMBERS

ChiCTR1900025419 and NCT04690192.

Lymphodepletion - an essential but undervalued part of the chimeric antigen receptor T-cell therapy cycle

Lymphodepletion (LD) or conditioning is an essential step in the application of currently used autologous and allogeneic chimeric antigen receptor T-cell (CAR-T) therapies as it maximizes engraftment, efficacy and long-term survival of CAR-T. Its main modes of action are the depletion and modulation of endogenous lymphocytes, conditioning of the microenvironment for improved CAR-T expansion and persistence, and reduction of tumor load. However, most LD regimens provide a broad and fairly unspecific suppression of T-cells as well as other hematopoietic cells, which can also lead to severe side effects, particularly infections. We reviewed 1271 published studies (2011-2023) with regard to current LD strategies for approved anti-CD19 CAR-T products for large B cell lymphoma (LBCL). Fludarabine (Flu) and cyclophosphamide (Cy) (alone or in combination) were the most commonly used agents. A large number of different schemes and combinations have been reported. In the respective schemes, doses of Flu and Cy (range 75-120mg/m2 and 750-1.500mg/m2) and wash out times (range 2-5 days) differed substantially. Furthermore, combinations with other agents such as bendamustine (benda), busulfan or alemtuzumab (for allogeneic CAR-T) were described. This diversity creates a challenge but also an opportunity to investigate the impact of LD on cellular kinetics and clinical outcomes of CAR-T. Only 21 studies explicitly investigated in more detail the influence of LD on safety and efficacy. As Flu and Cy can potentially impact both the in vivo activity and toxicity of CAR-T, a more detailed analysis of LD outcomes will be needed before we are able to fully assess its impact on different T-cell subsets within the CAR-T product. The T2EVOLVE consortium propagates a strategic investigation of LD protocols for the development of optimized conditioning regimens.

Phase 2 study of PD-1 blockade following autologous transplantation for patients with AML ineligible for allogeneic transplant

Allogeneic transplant remains the best postremission therapy for patients with nonfavorable risk acute myeloid leukemia (AML). However, some patients are ineligible because of psychosocial barriers, such as lack of appropriate caregiver support. We hypothesized that immune checkpoint inhibition after autologous transplant might represent effective postremission therapy in such patients. We conducted a phase 2 study of autologous transplantation followed by administration of pembrolizumab (8 cycles starting day +1). Twenty patients with nonfavorable AML in complete remission were treated (median age, 64 years; CR1, 80%); 55% were non-White and adverse-risk AML was present in 40%. Treatment was well tolerated, with only 1 nonrelapse death. Immune-related adverse events occurred in 9 patients. After a median follow-up of 80 months, 14 patients remain alive, with 10 patients in continuous remission. The estimated 2-year LFS was 48.4%, which met the primary end point of 2-year LFS >25%; the 2-year overall survival (OS), nonrelapse mortality, and cumulative incidences of relapse were 68%, 5%, and 46%, respectively. In comparison with a propensity score-matched cohort group of patients with AML receiving allogeneic transplant, the 3-year OS was similar (73% vs 76%). Patients in the study had inferior LFS (51% vs 75%) but superior postrelapse survival (45% vs 14%). In conclusion, programmed cell death protein-1 blockade after autologous transplant is a safe and effective alternative postremission strategy in patients with nonfavorable risk AML who are ineligible for allogeneic transplant, a context in which there is significant unmet need. This trial was registered at www.clinicaltrials.gov as #NCT02771197.

Clinical Benefit of Autologous Stem Cell Transplantation for Patients with Multiple Myeloma Achieving Undetectable Minimal Residual Disease after Induction Treatment

Attaining undetectable minimal residual disease (MRD) is the current therapeutic goal for multiple myeloma. But there is a current lack of data regarding the clinical benefit of autologous stem cell transplantation (ASCT) for patients with myeloma achieving early MRD-negative status after induction treatment, in addition to the interaction of longitudinal MRD status with ASCT. The current study included 407 patients with transplant-eligible multiple myeloma with available MRD status from the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199), of whom 147 (34.4%) achieved early undetectable MRD and 182 (44.7%) received ASCT. Early MRD-negative status was associated with a lower risk of disease progression [HR = 0.447; 95% confidence interval (CI), 0.333-0.600; P < 0.001] and death (HR = 0.473; 95% CI, 0.320-0.700; P < 0.001). Of note, patients who achieved undetectable MRD early still benefitted from ASCT, with a remarkable improvement in the median MRD-negative duration (33.5-58.0 months, P < 0.001), progression-free survival (PFS; 46.0-88.3 months, P < 0.001), and overall survival (OS; 76.4 months to not reached, P = 0.003). These clinical benefits were more pronounced in patients with aggressive features (high-risk cytogenetic abnormalities or high tumor burden) compared with standard-risk patients. Similar results were observed in patients with detectable MRD after induction treatment. In addition, we identified four MRD-status transformation patterns following ASCT, which were strongly correlated with diverse survival outcomes (P < 0.001). Our study revealed the enhanced clinical significance of ASCT in patients with transplant-eligible myeloma, regardless of early MRD status, particularly for high-risk patients. Subsequent prospective trials are essential to validate these observations.

Significance

Achieving and maintaining undetectable MRD is the current treatment goal for multiple myeloma. Our results emphasized the remarkable clinical benefit of ASCT on MRD-negative duration, PFS, and OS in patients with multiple myeloma regardless of early MRD status. These favorable impacts were more evident in patients with aggressive features. Importantly, dynamic MRD monitoring among ASCT could facilitate personalized stratification of therapeutic approaches.

Immunotherapy for neuroblastoma by hematopoietic cell transplantation and post-transplant immunomodulation

Neuroblastoma represents a relatively common childhood tumor that imposes therapeutic difficulties. High risk neuroblastoma patients have poor prognosis, display limited response to radiochemotherapy and may be treated by hematopoietic cell transplantation. Allogeneic and haploidentical transplants have the distinct advantage of reinstitution of immune surveillance, reinforced by antigenic barriers. The key factors favorable to ignition of potent anti-tumor reactions are transition to adaptive immunity, recovery from lymphopenia and removal of inhibitory signals that inactivate immune cells at the local and systemic levels. Post-transplant immunomodulation may further foster anti-tumor reactivity, with positive but transient impact of infusions of lymphocytes and natural killer cells both from the donor, the recipient or third party. The most promising approaches include introduction of antigen-presenting cells in early post-transplant stages and neutralization of inhibitory signals. Further studies will likely shed light on the nature and actions of suppressor factors within tumor stroma and at the systemic level.

Cellular Cancer Immunotherapy Development and Manufacturing in the Clinic

The transfusion of naturally derived or modified cellular therapies, referred to as adoptive cell therapy (ACT), has demonstrated clinical efficacy in the treatment of hematologic malignancies and metastatic melanoma. In addition, cellular vaccination, such as dendritic cell-based cancer vaccines, continues to be actively explored. The manufacturing of these therapies presents a considerable challenge to expanding the use of ACT as a viable treatment modality, particularly at academic production facilities. Furthermore, the expanding commercial interest in ACT presents new opportunities as well as strategic challenges for the future vision of cellular manufacturing in academic centers. Current trends in the production of ACT at tertiary care centers and prospects for improved manufacturing practices that will foster further clinical benefit are reviewed herein.

Immunotherapy reverses glioma-driven dysfunction of immune system homeostasis

BACKGROUND

Glioma-induced immune dysregulation of the hematopoietic system has been described in a limited number of studies. In this study, our group further demonstrates that gliomas interrupt the cellular differentiation programming and outcomes of hematopoietic stem and progenitor cells (HSPCs) in the bone marrow. HSPCs from glioma-bearing mice are reprogrammed and driven towards expansion of myeloid lineage precursors and myeloid-derived suppressor cells (MDSCs) in secondary lymphoid organs. However, we found this expansion is reversed by immunotherapy. Adoptive cellular therapy (ACT) has been demonstrably efficacious in multiple preclinical models of central nervous system (CNS) malignancies, and here we describe how glioma-induced dysfunction is reversed by this immunotherapeutic platform.

METHODS

The impact of orthotopic KR158B-luc glioma on HSPCs was evaluated in an unbiased fashion using single cell RNAseq (scRNAseq) of lineage- cells and phenotypically using flow cytometry. Mature myeloid cell frequencies and function were also evaluated using flow cytometry. Finally, ACT containing total body irradiation, tumor RNA-pulsed dendritic cells, tumor-reactive T cells and HSPCs isolated from glioma-bearing or non-tumor-bearing mice were used to evaluate cell fate differentiation and survival.

RESULTS

Using scRNAseq, we observed an altered HSPC landscape in glioma-bearing versus non-tumor-bearing mice . In addition, an expansion of myeloid lineage subsets, including granulocyte macrophage precursors (GMPs) and MDSCs, were observed in glioma-bearing mice relative to non-tumor-bearing controls. Furthermore, MDSCs from glioma-bearing mice demonstrated increased suppressive capacity toward tumor-specific T cells as compared with MDSCs from non-tumor-bearing hosts. Interestingly, treatment with ACT overcame these suppressive properties. When HSPCs from glioma-bearing mice were transferred in the context of ACT, we observed significant survival benefit and long-term cures in orthotopic glioma models compared with mice treated with ACT using non-glioma-bearing HSPCs.

Gut microbiome in multiple myeloma: Mechanisms of progression and clinical applications

The gut commensal microbes modulate human immunity and metabolism through the production of a large number of metabolites, which act as signaling molecules and substrates of metabolic reactions in a diverse range of biological processes. There is a growing appreciation for the importance of immunometabolic mechanisms of the host-gut microbiota interactions in various malignant tumors. Emerging studies have suggested intestinal microbiota contributes to the progression of multiple myeloma. In this review, we summarized the current understanding of the gut microbiome in MM progression and treatment, and the influence of alterations in gut microbiota on treatment response and treatment-related toxicity and complications in MM patients undergoing hematopoietic stem cell transplantation (HSCT). Furthermore, we discussed the impact of gut microbiota-immune system interactions in tumor immunotherapy, focusing on tumor vaccine immunotherapy, which may be an effective approach to improve anti-myeloma efficacy.

Pro- and Anti-Tumoral Factors Involved in Total Body Irradiation and Interleukin-2 Conditioning in Adoptive T Cell Therapy of Melanoma-Bearing Rag1 Knock-Out Mice

In adoptive T cell therapy (ACT), the transfer of tumor-specific T cells is paralleled by the conditioning regimen to increase therapeutic efficacy. Pre-conditioning depletes immune-suppressive cells and post-conditioning increases homeostatic signals to improve the persistence of administered T cells. Identifying the favorable immunological factors involved in a conditioning regimen is important to design effective strategies in ACT. Here, by using an ACT model of murine melanoma, we evaluate the effect of the total body irradiation (TBI) and interleukin-2 (IL-2) treatment combination. The use of a Rag1 knock-out strain, which lacks endogenous T cells, enables the identification of factors in a way that focuses more on transferred T cells. We demonstrate that the TBI/IL-2 combination has no additive effect in ACT, although each conditioning improves the therapeutic outcome. While the combination increases the frequency of transferred T cells in lymphoid and tumor tissues, the activation intensity of the cells is reduced compared to that of the sole TBI treatment. Notably, we show that in the presence of TBI, the IL-2 treatment reduces the frequency of intra-tumoral dendritic cells, which are crucial for T cell activation. The current study provides insights into the immunological events involved in the TBI/IL-2 combination in ACT.

The Autologous Hematopoietic Stem Cells Transplantation Combination-Based Chimeric Antigen Receptor T-Cell Therapy Improves Outcomes of Relapsed/Refractory Central Nervous System B-Cell Lymphoma

OBJECTIVE

The objective is to explore the effectiveness and safety of CAR T-cell therapy in advanced relapsed/refractory central nervous system B-cell lymphoma and compare the impact of autologous stem cell transplantation (ASCT) plus CAR T-cell therapy versus sequential CART therapy on the survival of patients.

METHODS

The retrospective analysis was based on the data of 17 patients with advanced relapsed/refractory central nervous system B-cell lymphoma. Bridging chemotherapy was applied before CAR T-cell infusion to further reduce the tumor burden. For patients with autologous hematopoietic stem cell successful collection, CD19/20/22CAR T-cell immunotherapy following ASCT was performed with the thiotepa-containing conditioning regimen, while sequential CD19/CD20/CD22CAR T-cell therapy was applied. For lymphodepletion, patients received bendamustine or fludarabine monotherapy or fludarabine combined with cyclophosphamide pre-CART-cell infusion.

RESULTS

Out of the 17 patients, 8 completed ASCT plus CART cell therapy, while 9 patients completed CART cell alone therapy. In efficacy assessment at 3 months after infusion, the objective response rate (ORR) was 12/17 (71%) and the complete response rate (CRR) was 11/17 (65%). The CRR of the ASCT group and non-ASCT was 100% and 44.4%, respectively (P < 0.01). The median progression-free survival was 16.3 (2.6-24.5) months, and the median overall survival was 19.3 (6-24.5) months. Patients who underwent ASCT plus CART cell therapy had significantly longer PFS (P < 0.01) and OS (P < 0.01). Grade 3 or higher immune effector cell-associated neurologic toxicity syndrome (≥grade 3 ICANS) and cytokine release syndrome (≥grade 3 CRS) events occurred in 29% and 41% of the patients, respectively. No treatment-related death occurred.

CONCLUSION

The CAR T-cell therapy could augment its efficacy in the treatment of advanced relapsed/refractory CNS B-cell lymphoma, while ASCT in combination with CART can induce durable responses and OS with a manageable side effect.

Current State of Cell Therapies for Breast Cancer

Metastatic breast cancer (BC) is an aggressive form of cancer and is an absolute challenge to treat. This review discusses the standard treatments available for metastatic BC. It further highlights the rationale for targeting oncodrivers, tumor-associated antigens, and neoantigens in BC. Explaining the significance of immune response in successful immunotherapeutic studies, it draws attention towards how adoptive cell therapy can be a useful immunotherapeutic tool. We focus on adoptive cell therapy in BC covering tumor-infiltrating lymphocyte therapy, engineered T cell receptor therapy, chimeric antigen receptor therapy, dendritic cell therapy and natural killer cell therapy. In this work, we aim to provide an overview of clinical data regarding the use of cellular immunotherapies in BC. Eventually, we conclude by proposing future adoptive cell therapy approaches, which can be used to cure BC.

Sequential CAR T-Cell Therapy After Autologous Stem Cell Transplantation for the Treatment of Relapsed/Refractory Intravascular Large B-Cell Lymphoma With Central Nervous System Involvement: A Case Report

Background

Intravascular large B-cell lymphoma (IVLBCL) is a rare, aggressive, large B-cell non-Hodgkin’s lymphoma. The prognosis of IVLBCL in patients with central nervous system recurrence after first-line chemotherapy treatment is extremely poor. Among immunotherapies, chimeric antigen receptor (CAR) T-cell immunotherapy has been recently found to be a highly effective treatment for B-cell lymphoma, especially for relapsed or refractory diffuse large B-cell lymphoma. However, no guidelines are available that provide a clear consensus regarding the management of patients with relapsed/refractory IVLBCL. Here, we report, for the first time, the use of autologous hematopoietic stem cell transplantation (ASCT) and CAR T-cell therapy in a patient with relapsed/refractory IVLBCL.

Case Presentation

A 42‐year‐old woman was diagnosed with IVLBCL based on liver biopsy and developed central nervous system (CNS) progression. The patient received ASCT combined with murine monoclonal anti-CD19 and anti-CD22 CAR T-cell therapy. She achieved complete remission for 22 months so far with negative minimal residual disease and continues to be followed up.

Conclusion

ASCT combined with CAR T-cell therapy was the best choice for treatment of relapsed/refractory IVLBCL, as it allowed the achievement of a lasting complete remission.

Applications of Extracellular Vesicles in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive and refractory subtype of breast cancer, often occurring in younger patients with poor clinical prognosis. Given the current lack of specific targets for effective intervention, the development of better treatment strategies remains an unmet medical need. Over the last decade, the field of extracellular vesicles (EVs) has grown tremendously, offering immense potential for clinical diagnosis/prognosis and therapeutic applications. While TNBC-EVs have been shown to play an important role in tumorigenesis, chemoresistance and metastasis, they could be repurposed as potential biomarkers for TNBC diagnosis and prognosis. Furthermore, EVs from various cell types can be utilized as nanoscale drug delivery systems (NDDS) for TNBC treatment. Remarkably, EVs generated from specific immune cell subsets have been shown to delay solid tumour growth and reduce tumour burden, suggesting a new immunotherapy approach for TNBC. Intrinsically, EVs can cross the blood-brain barrier (BBB), which holds great potential to treat the brain metastases diagnosed in one third of TNBC patients that remains a substantial clinical challenge. In this review, we present the most recent applications of EVs in TNBC as diagnostic/prognostic biomarkers, nanoscale drug delivery systems and immunotherapeutic agents, as well as discuss the associated challenges and future directions of EVs in cancer immunotherapy.

CD19/CD22 Chimeric Antigen Receptor T Cell Cocktail Therapy following Autologous Transplantation in Patients with Relapsed/Refractory Aggressive B Cell Lymphomas

High-dose chemotherapy followed by autologous stem cell transplantation (HDT-ASCT) is the standard of care for chemosensitive relapsed or refractory (R/R) aggressive B cell lymphoma. Patients with a positive positron emission tomography (PET) scan before ASCT have a poor prognosis, and those who fail to achieve a therapeutic response better than partial remission after salvage treatment are ineligible candidates for ASCT. We conducted this open-label single-arm prospective clinical study to evaluate the safety and efficacy of sequential infusion of CD19/22 chimeric antigen receptor (CAR) T cells following HDT-ASCT. Eligibility for this study included patients with R/R aggressive B cell non-Hodgkin lymphoma (B-NHL) with ¹⁸F-fluorodeoxyglucose-PET positivity and patients with stable or progressive disease after salvage chemotherapy. Between November 14, 2016, and August 15, 2019, 42 patients underwent HDT-ASCT followed by CD19/22 CAR T cell infusion. Grade 3 cytokine release syndrome (CRS) occurred in only 2 patients. Twenty-one percent of patients experienced any grade of neurotoxicity, 5% with severe grade 3. All cases of CRS and neurotoxicity were reversible. The overall response rate was 90.5% (95% confidence interval [CI], 77.4% to 97.3%). At a median follow-up of 24.3 months, the median progression-free survival (PFS) and overall survival were not reached. The 2-year PFS rate was 83.3 % (95% CI, 68.2% to 91.7%). No patients were found to be CD19- and CD22-negative at the time of progression; 97.1% and 68.6% of patients with ongoing complete remission (CR) had consistently detectable levels of CD19 and CD22 CAR transgene, respectively, at 3 months. The median time to onset of sustained B cell recovery was 8.2 months. The high durable CR rates and favorable safety profiles support the strong potential of the HDT-ASCT plus CD19/CD22 CAR T cell cocktail therapy for the suboptimal group of patients with R/R aggressive B-NHL who are less sensitive or fail salvage chemotherapy. These early data are encouraging and informative for future trials to further test the efficacy and safety of HDT-ASCT plus CAR T cell therapy in a larger population. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Sequential CD19/22 CAR T-cell immunotherapy following autologous stem cell transplantation for central nervous system lymphoma

Chimeric antigen receptor (CAR) T-cell immunotherapy following autologous stem cell transplantation (ASCT) is a promising method for refractory or relapsed multiple myeloma, but explicit data for central nervous system lymphoma (CNSL) are lacking. Here, we treated 13 CNSL patients with ASCT sequential CD19/22 CAR T-cell infusion and simultaneously evaluated the clinical efficacy and toxicity. The 13 CNSL patients analyzed included four primary CNSL and nine secondary CNSL patients. Patients 1 and 10, who had complete remission status before enrollment, maintained clinical efficacy without recurrence. Nine of the remaining 11 patients responded to our protocol with a median durable time of 14.03 months, and the overall response and complete remission rate were 81.81% and 54.55%, respectively. No patient suffered grades 3–4 cytokine-release syndrome (CRS), and only patient 10 experienced severe immune effector cell-associated neurotoxicity syndrome (ICANS). In addition, increases in serum ferritin and interleukin-6 levels were often accompanied by CRS and ICANS. After a median follow-up time of 14.20 months, the estimated 1-year progression-free survival and overall survival rates were 74.59% and 82.50%, respectively. Sequential CD19/22 CAR T-cell immunotherapy following ASCT as a novel method for CNSL appears to have encouraging long-term efficacy with relatively manageable side effects.

Myelopoiesis during Solid Cancers and Strategies for Immunotherapy

Our understanding of the relationship between the immune system and cancers has undergone significant discovery recently. Immunotherapy with T cell therapies and checkpoint blockade has meaningfully changed the oncology landscape. While remarkable clinical advances in adaptive immunity are occurring, modulation of innate immunity has proven more difficult. The myeloid compartment, including macrophages, neutrophils, and dendritic cells, has a significant impact on the persistence or elimination of tumors. Myeloid cells, specifically in the tumor microenvironment, have direct contact with tumor tissue and coordinate with tumor-reactive T cells to either stimulate or antagonize cancer immunity. However, the myeloid compartment comprises a broad array of cells in various stages of development. In addition, hematopoietic stem and progenitor cells at various stages of myelopoiesis in distant sites undergo significant modulation by tumors. Understanding how tumors exert their influence on myeloid progenitors is critical to making clinically meaningful improvements in these pathways. Therefore, this review will cover recent developments in our understanding of how solid tumors modulate myelopoiesis to promote the formation of pro-tumor immature myeloid cells. Then, it will cover some of the potential avenues for capitalizing on these mechanisms to generate antitumor immunity.

Reactive myelopoiesis and the onset of myeloid-mediated immune suppression: Implications for adoptive cell therapy

Adoptive T cell therapy (ACT) in combination with lymphodepleting chemotherapy is an effective strategy to induce the eradication of cancer, providing long-term regressions in patients. However, only a minority of patients that receive ACT with tumor-specific T cells exhibit durable benefit. Thus, there is an urgent need to characterize mechanisms of resistance and define strategies to alleviate immunosuppression in the context of ACT in cancer. This article reviews the importance of lymphodepleting regimens in promoting the optimal engraftment and expansion of T cells in hosts after adoptive transfer. In addition, we discuss the role of concomitant immunosuppression and the accumulation of myeloid derived suppressor cells (MDSCs) during immune recovery after lymphodepleting regimens and mobilization regimens.

To Remember or to Forget: The Role of Good and Bad Memories in Adoptive T Cell Therapy for Tumors

The generation of immunological memory is a hallmark of adaptive immunity by which the immune system “remembers” a previous encounter with an antigen expressed by pathogens, tumors, or normal tissues; and, upon secondary encounters, mounts faster and more effective recall responses. The establishment of T cell memory is influenced by both cell-intrinsic and cell-extrinsic factors, including genetic, epigenetic and environmental triggers. Our current knowledge of the mechanisms involved in memory T cell differentiation has instructed new opportunities to engineer T cells with enhanced anti-tumor activity. The development of adoptive T cell therapy has emerged as a powerful approach to cure a subset of patients with advanced cancers. Efficacy of this approach often requires long-term persistence of transferred T cell products, which can vary according to their origin and manufacturing conditions. Host preconditioning and post-transfer supporting strategies have shown to promote their engraftment and survival by limiting the competition with a hostile tumor microenvironment and between pre-existing immune cell subsets. Although in the general view pre-existing memory can confer a selective advantage to adoptive T cell therapy, here we propose that also “bad memories”—in the form of antigen-experienced T cell subsets—co-evolve with consequences on newly transferred lymphocytes. In this review, we will first provide an overview of selected features of memory T cell subsets and, then, discuss their putative implications for adoptive T cell therapy.

CAR T-Cell Therapy Is Effective but Not Long-Lasting in B-Cell Lymphoma of the Brain

Advanced central nervous system (CNS) lymphoma is an exclusion criterion for most chimeric antigen receptor (CAR) T-cell studies due to the associated levels of neurotoxicity. In this study, we described five patients with chemorefractory B-cell CNS lymphoma who received CAR19 and CAR22 T-cell “Cocktail” therapy and follow-up for 6–16 months. All patients experienced cytokine release syndrome (CRS). Two patients experienced CAR T-cell-related encephalopathy syndrome (CRES), which was controllable. The best response was observed in two patients, who successfully achieved complete remissions (CR), and the other three patients achieved partial remissions (PR). Four patients had progressive disease (PD) after remission. In addition, one CR patient and one PD patient accepted CAR T-cell infusion following hematopoietic stem cell transplantation therapy in the 3rd month and were in ongoing remission for 14 and 6 months of follow-up, respectively. The targeted antigens in two patients were still positive, and CAR T-cells were reboosted in the cerebrospinal fluid (CSF) after PD, but a small number of CD3-positive T-cells were observed to infiltrate into the tumor. Our study indicates the efficacy of CAR T-cell therapy for CNS lymphoma with an acceptable safety profile; however, the remission did not last long, perhaps due to the tumor immunosuppressive microenvironment (TME) of the CNS. CAR T-cell therapy should be combined with other treatments to help improve the TME of cerebral lymphoma.

Tumor response and endogenous immune reactivity after administration of HER2 CAR T cells in a child with metastatic rhabdomyosarcoma

Refractory metastatic rhabdomyosarcoma is largely incurable. Here we analyze the response of a child with refractory bone marrow metastatic rhabdomyosarcoma to autologous HER2 CAR T cells. Three cycles of HER2 CAR T cells given after lymphodepleting chemotherapy induces remission which is consolidated with four more CAR T-cell infusions without lymphodepletion. Longitudinal immune-monitoring reveals remodeling of the T-cell receptor repertoire with immunodominant clones and serum autoantibodies reactive to oncogenic signaling pathway proteins. The disease relapses in the bone marrow at six months off-therapy. A second remission is achieved after one cycle of lymphodepletion and HER2 CAR T cells. Response consolidation with additional CAR T-cell infusions includes pembrolizumab to improve their efficacy. The patient described here is a participant in an ongoing phase I trial (NCT00902044; active, not recruiting), and is 20 months off T-cell infusions with no detectable disease at the time of this report.

Generation of Myeloid Cells in Cancer: The Spleen Matters

Myeloid cells are key components of the tumor microenvironment and critical regulators of disease progression. These innate immune cells are usually short-lived and require constant replenishment. Emerging evidence indicates that tumors alter the host hematopoietic system and induce the biased differentiation of myeloid cells to tip the balance of the systemic immune activities toward tumor-promoting functions. Altered myelopoiesis is not restricted to the bone marrow and also occurs in extramedullary organs. In this review, we outline the recent advances in the field of cancer-associated myelopoiesis, with a focus on the spleen, the major site of extramedullary hematopoiesis in the cancer setting. We discuss the functional specialization, distinct mechanisms, and clinical relevance of cancer-associated myeloid cell generation from early progenitors in the spleen and its potential as a novel therapeutic target.

Key Factors in Clinical Protocols for Adoptive Cell Therapy in Melanoma

Adoptive cell therapy (ACT) with autologous tumor infiltrating lymphocytes (TIL) has been studied for patients with advanced metastatic cancers (primarily melanoma) for decades and has changed significantly during that period. Treatment with TIL includes ex vivo cell activation and expansion followed by re-infusion of these cells into the patient. After cell infusion, patients receive Interleukin-2 (IL-2). Objective response rates up to 52% have been seen in patients with metastatic melanoma. Efforts to improve TIL therapy include better selection and expansion of tumor-reactive lymphocytes, optimization of IL-2 or other T cell activating cytokine dosing, and, potentially, genetic manipulation of the immune cell product. Here we describe methods involved in the collection, expansion, and treatment with TIL for patients with metastatic melanoma.

CD19 CAR T cells following autologous transplantation in poor-risk relapsed and refractory B-cell non-Hodgkin lymphoma

High-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT) is the standard of care for relapsed or primary refractory (rel/ref) chemorefractory diffuse large B-cell lymphoma. Only 50% of patients are cured with this approach. We investigated safety and efficacy of CD19-specific chimeric antigen receptor (CAR) T cells administered following HDT-ASCT. Eligibility for this study includes poor-risk rel/ref aggressive B-cell non-Hodgkin lymphoma chemosensitive to salvage therapy with: (1) positron emission tomography-positive disease or (2) bone marrow involvement. Patients underwent standard HDT-ASCT followed by 19-28z CAR T cells on days +2 and +3. Of 15 subjects treated on study, dose-limiting toxicity was observed at both dose levels (5 × 10⁶ and 1 × 10⁷ 19-28z CAR T per kilogram). Ten of 15 subjects experienced CAR T-cell-induced neurotoxicity and/or cytokine release syndrome (CRS), which were associated with greater CAR T-cell persistence (P = .05) but not peak CAR T-cell expansion. Serum interferon-γ elevation (P < .001) and possibly interleukin-10 (P = .07) were associated with toxicity. The 2-year progression-free survival (PFS) is 30% (95% confidence interval, 20% to 70%).  Subjects given decreased naive-like (CD45RA⁺CCR7⁺) CD4⁺ and CD8⁺ CAR T cells experienced superior PFS (P = .02 and .04, respectively). There was no association between CAR T-cell peak expansion, persistence, or cytokine changes and PFS. 19-28z CAR T cells following HDT-ASCT were associated with a high incidence of reversible neurotoxicity and CRS. Following HDT-ASCT, effector CD4⁺ and CD8⁺ immunophenotypes may improve disease control. This trial was registered at www.clinicaltrials.gov as #NCT01840566.

miR-155 expression in antitumor immunity: The higher the better?

MicroRNAs are small noncoding RNAs that modulate gene expression either directly, by impairing the stability and/or translation of transcripts that contain their specific target sequence, or indirectly through the targeting of transcripts that encode transcription factors, factors implicated in signal transduction pathways, or epigenetic regulators. Abnormal expression of micro-RNAs has been found in nearly all types of pathologies, including cancers. MiR-155 has been the first microRNA to be implicated in the regulation of the innate and adaptative immune responses, and its expression is either increased or decreased in a variety of liquid and solid malignancies. In this review, we examine the oncogenic and antitumor potentials of miR-155, with special emphasize on its dose-dependent effects. We describe the impact of miR-155 levels on antitumor activity of lymphocytes and myeloid cells. We discuss miR-155 dose-dependent effects in leukemias and analyze results showing that miR-155 intermediate levels tend to be detrimental, whereas high levels of miR-155 expression usually prove beneficial. We also examine the beneficial effects of high levels of miR-155 expression in solid tumors. We discuss the possible causal involvement of miR-155 in leukemias and dementia in individuals with Down's syndrome. We finally propose that increasing miR-155 levels in immune cells might increase the efficiency of newly developed cancer immunotherapies, due to miR-155 ability to target transcripts encoding immune checkpoints such as cytotoxic T lymphocyte antigen-4 or programmed death-ligand 1.

Current Status and Future Directions of Immunotherapy in Renal Cell Carcinoma

PURPOSE OF REVIEW

Renal cell carcinoma (RCC) was recognized as an immunologically sensitive cancer over 30 years ago. The first therapies to affect the course of RCC were cytokines (interferon alfa-2B and interleukin-2). Subsequently, drugs that inhibit HIF (hypoxia-inducible factor)/VEGF (vascular endothelial growth factor) signaling demonstrated overall survival advantages (tyrosine kinase inhibitors and mTor inhibitors).

RECENT FINDINGS

In the last 3 years, the immune checkpoint inhibitors (ICIs) have become the standard of care treatments in the first and second lines for RCC. Emerging data show that combinations of ICI, HIF signaling inhibitors, and cytokines are potentially powerful regimens. How to combine and sequence these types of therapies and how to integrate new approaches into the management of RCC are now the key questions for the field. Treatment of RCC is likely to change dramatically in the next few years.

Autologous Lymphocyte Infusion Supports Tumor Antigen Vaccine-Induced Immunity in Autologous Stem Cell Transplant for Multiple Myeloma

Autologous stem cell transplant (autoSCT), the standard consolidation therapy for multiple myeloma, improves disease-free survival, but is not curative. This could be an ideal setting for immunologic therapy. However, the immune milieu is impaired after autoSCT. We hypothesized that autologous lymphocyte infusion would restore immune competence, allowing immunotherapies such as cancer vaccines to elicit tumor antigen-specific immunity in the setting of autoSCT. In this pilot study (NCT01380145), we investigated safety, immunologic, and clinical outcomes of autologous lymphocyte infusion combined with peri-autoSCT immunotherapy with recombinant MAGE-A3 (a multiple myeloma-associated antigen) and adjuvant. Thirteen patients with multiple myeloma undergoing autoSCT were enrolled. Autologous lymphocyte infusion and MAGE vaccination were well tolerated. Combination immunotherapy resulted in high-titer humoral immunity and robust, antigen-specific CD4⁺ T-cell responses in all subjects, and the responses persisted at least one year post-autoSCT. CD4⁺ T cells were polyfunctional and Th1-biased. CD8⁺ T-cell responses were elicited in 3 of 13 subjects. These cells recognized naturally processed MAGE-A3 antigen. Median progression-free survival was 27 months, and median overall survival was not reached, suggesting no differences from standard-of-care. In 4 of 8 subjects tested, MAGE-A protein expression was not detected by IHC in multiple myeloma cells at relapse, suggesting therapy-induced immunologic selection against antigen-expressing clones. These results demonstrated that autologous lymphocyte infusion augmentation of autoSCT confers a favorable milieu for immunotherapies such as tumor vaccines. This strategy does not require ex vivo manipulation of autologous lymphocyte products and is an applicable platform for further investigation into combination immunotherapies to treat multiple myeloma.

Concise Review: Modulating Cancer Immunity with Hematopoietic Stem and Progenitor Cells

Hematopoietic stem and progenitor cells (HSPCs) are the progenitor cells that can regenerate the entire blood compartment, including the immune system. Recent studies have unearthed considerable immune-modulating potential of these cells. They can migrate through chemotactic gradients, differentiate into functional immune cells, and crosstalk with immune cells during infections, autoimmune diseases, and cancers. Although the primary role of HSPCs during solid malignancies is considered immunosuppressive, recent studies have discovered immune-activating HSPCs and progeny. In this review, we will discuss the recent evidence that HSPCs act as immunomodulators during solid cancers and highlight the future directions of discovery. Stem Cells 2019;37:166-175.

Cross-talk between T Cells and Hematopoietic Stem Cells during Adoptive Cellular Therapy for Malignant Glioma

Purpose: Adoptive T-cell immunotherapy (ACT) has emerged as a viable therapeutic for peripheral and central nervous system (CNS) tumors. In peripheral cancers, optimal efficacy of ACT is reliant on dendritic cells (DCs) in the tumor microenvironment. However, the CNS is largely devoid of resident migratory DCs to function as antigen-presenting cells during immunotherapy. Herein, we demonstrate that cellular interactions between adoptively transferred tumor-reactive T cells and bone marrow-derived hematopoietic stem and progenitor cells (HSPCs) lead to the generation of potent intratumoral DCs within the CNS compartment.Experimental Design: We evaluated HSPC differentiation during ACT in vivo in glioma-bearing hosts and HSPC proliferation and differentiation in vitro using a T-cell coculture system. We utilized FACS, ELISAs, and gene expression profiling to study the phenotype and function of HSPC-derived cells ex vivo and in vivo To demonstrate the impact of HSPC differentiation and function on antitumor efficacy, we performed survival experiments.Results: Transfer of HSPCs with concomitant ACT led to the production of activated CD86+CD11c+MHCII+ cells consistent with DC phenotype and function within the brain tumor microenvironment. These intratumoral DCs largely supplanted abundant host myeloid-derived suppressor cells. We determined that during ACT, HSPC-derived cells in gliomas rely on T-cell-released IFNγ to differentiate into DCs, activate T cells, and reject intracranial tumors.Conclusions: Our data support the use of HSPCs as a novel cellular therapy. Although DC vaccines induce robust immune responses in the periphery, our data demonstrate that HSPC transfer uniquely generates intratumoral DCs that potentiate T-cell responses and promote glioma rejection in situClin Cancer Res; 24(16); 3955-66. ©2018 AACR.

Intraperitoneal oxaliplatin administration inhibits the tumor immunosuppressive microenvironment in an abdominal implantation model of colon cancer

Recent studies have demonstrated that some chemotherapeutic drugs can enhance antitumor immunity by eliminating and inactivating immunosuppressive cells. Oxaliplatin (OXP) induces immunogenic cell death by increasing the immunogenicity of cancer cells. However, the effects of OXP on the tumor immunosuppressive microenvironment remain unclear. The aim of the present study was to evaluate the antitumor activity of OXP by intraperitoneal (i.p.) administration in an abdominal implantation model of colon cancer and tested the tumor immune microenvironment to observe whether OXP affects the local immune inhibitory cell populations. Abdominal metastasis models were established by inoculation of CT26 cells. The antitumor efficacy of OXP and the tumor immune microenvironment were evaluated. The tumors and spleens of mice were harvested for flow cytometric analysis. Cluster of differentiation (CD)‑8+CD69+ T cells, regulatory T cells (Tregs), CD11b+F4/80high macrophages and myeloid‑derived suppressor cells (MDSCs) were evaluated by flow cytometric analysis. In vivo i.p. administration of OXP inhibited tumor growth in the abdominal metastasis model. Furthermore, OXP was observed to increase tumor‑infiltrating activated CD8+ T cells in tumors, decrease CD11b+F4/80high macrophages in tumors and decrease MDSCs in the spleen. These results suggested that i.p. administration of OXP alone may inhibit tumor cell growth and induce the antitumor immunostimulatory microenvironment by eliminating immunosuppressive cells.

Enhanced Lymphodepletion Is Insufficient to Replace Exogenous IL2 or IL15 Therapy in Augmenting the Efficacy of Adoptively Transferred Effector CD8+ T Cells

Effector CD8⁺ T cells conditioned with IL12 during activation mediate enhanced antitumor efficacy after adoptive transfer into lymphodepleted hosts; this is due in part to improved IL7 responsiveness. Therefore, we hypothesized that increasing the intensity or type of lymphodepletion would deplete more IL7-consuming host cells and improve the persistence and antitumor activity of IL12-conditioned CD8⁺ T cells. Using cyclophosphamide, fludarabine, and total body irradiation (TBI, 6 Gy) either individually or in combination, we found that combined lymphodepletion best enhanced T-cell engraftment in mice. This improvement was strongly related to the extent of leukopenia, as posttransfer levels of donor T cells inversely correlated to host cell counts after lymphodepletion. Despite the improvement in engraftment seen with combination lymphodepletion, dual-agent lymphodepletion did not augment the antitumor efficacy of donor T cells compared with TBI alone. Similarly, IL7 supplementation after TBI and transfer of tumor-reactive T cells failed to improve persistence or antitumor immunity. However, IL15 or IL2 supplementation greatly augmented the persistence and antitumor efficacy of donor tumor-reactive T cells. Our results indicate that the amount of host IL7 induced after single agent lymphodepletion is sufficient to potentiate the expansion and antitumor activity of donor T cells, and that the efficacy of future regimens may be improved by providing posttransfer support with IL2 or IL15.Significance: The relationship between lymphodepletion and cytokine support plays a critical role in determining donor T-cell engraftment and antitumor efficacy. Cancer Res; 78(11); 3067-74. ©2018 AACR.

Tumor-Resident Dendritic Cells and Macrophages Modulate the Accumulation of TCR-Engineered T Cells in Melanoma

Ongoing clinical trials explore T cell receptor (TCR) gene therapy as a treatment option for cancer, but responses in solid tumors are hampered by the immunosuppressive microenvironment. The production of TCR gene-engineered T cells requires full T cell activation in vitro, and it is currently unknown whether in vivo interactions with conventional dendritic cells (cDCs) regulate the accumulation and function of engineered T cells in tumors. Using the B16 melanoma model and the inducible depletion of CD11c⁺ cells in CD11c.diphtheria toxin receptor (DTR) mice, we analyzed the interaction between tumor-resident cDCs and engineered T cells expressing the melanoma-specific TRP-2 TCR. We found that depletion of CD11c⁺ cells triggered the recruitment of cross-presenting cDC1 into the tumor and enhanced the accumulation of TCR-engineered T cells. We show that the recruited tumor cDCs present melanoma tumor antigen, leading to enhanced activation of TCR-engineered T cells. In addition, detailed analysis of the tumor myeloid compartment revealed that the depletion of a population of DT-sensitive macrophages can contribute to the accumulation of tumor-infiltrating T cells. Together, these data suggest that the relative frequency of tumor-resident cDCs and macrophages may impact the therapeutic efficacy of TCR gene therapy in solid tumors.

Informatics for cancer immunotherapy

The rapid development of immunomodulatory cancer therapies has led to a concurrent increase in the application of informatics techniques to the analysis of tumors, the tumor microenvironment, and measures of systemic immunity. In this review, the use of tumors to gather genetic and expression data will first be explored. Next, techniques to assess tumor immunity are reviewed, including HLA status, predicted neoantigens, immune microenvironment deconvolution, and T-cell receptor sequencing. Attempts to integrate these data are in early stages of development and are discussed in this review. Finally, we review the application of these informatics strategies to therapy development, with a focus on vaccines, adoptive cell transfer, and checkpoint blockade therapies.

In Vivo Murine-Matured Human CD3+ Cells as a Preclinical Model for T Cell-Based Immunotherapies

Adoptive cellular immunotherapy is a promising and powerful method for the treatment of a broad range of malignant and infectious diseases. Although the concept of cellular immunotherapy was originally proposed in the 1990s, it has not seen successful clinical application until recent years. Despite significant progress in creating engineered receptors against both malignant and viral epitopes, no efficient preclinical animal models exist for rapidly testing and directly comparing these engineered receptors. The use of matured human T cells in mice usually leads to graft-versus-host disease (GvHD), which severely limits the effectiveness of such studies. Alternatively, adult apheresis CD34⁺ cells engraft in neonatal non-obese diabetic (NOD)-severe combined immunodeficiency (SCID)-common γ chain^–/– (NSG) mice and lead to the development of CD3⁺ T cells in peripheral circulation. We demonstrate that these in vivo murine-matured autologous CD3⁺ T cells from humans (MATCH) can be collected from the mice, engineered with lentiviral vectors, reinfused into the mice, and detected in multiple lymphoid compartments at stable levels over 50 days after injection. Unlike autologous CD3⁺ cells collected from human donors, these MATCH mice did not exhibit GvHD after T cell administration. This novel mouse model offers the opportunity to screen different immunotherapy-based treatments in a preclinical setting.

Effect of administration timing of postchemotherapy granulocyte colony-stimulating factor on host-immune cell recovery and CD8+ T-cell response

Granulocyte colony-stimulating factor (G-CSF), a hematopoietic growth factor, is a standard supportive therapy given during cancer treatment. It induces acceleration in neutrophil recovery through stimulation of mobilization of hematopoietic progenitors. Given that the latter is also induced by chemotherapy itself, the timing of administration of G-CSF postchemotherapy might impact the resultant overall effects. The present study aimed to determine the optimal timing of G-CSF postchemotherapy to exert its optimal effects on the immune cell recovery and its impact on antigen-specific CD8⁺ T-cell response. B6 mice were treated once with cyclophosphamide (4 mg/mouse; CTX) and then daily with G-CSF (5 g/mouse) from Days 1-5, 2-5 or 5-9 post-CTX treatment. The total numbers of various immune cell types were analyzed on Days 7, 9 and 12 post-CTX treatment. To evaluate effects on CD8⁺ T-cell response, a pmel-1 transgenic mouse model was used in combination with prime boost peptide vaccination therapy. The total number of white blood cells (WBC), neutrophils, monocytes, lymphocytes, granulocytes and dendritic cells (DC) were significantly increased after G-CSF treatment in particular when G-CSF was administered from Days 2-5 post-CTX treatment. Application of this timing of G-CSF and CTX treatment after adoptive transfer of T-cells followed by prime-boost vaccination with antigenic peptide did not block the expansion of the donor pmel-1 CD8⁺ T-cells. In conclusion, adjusting the timing of treatment with G-CSF postchemotherapy can optimize its promoting effects on recovery of myeloid cells without altering the associated antigen-specific immunity.

Concepts and mechanisms underlying chemotherapy induced immunogenic cell death: impact on clinical studies and considerations for combined therapies

Chemotherapy has historically been thought to induce cancer cell death in an immunogenically silent manner. However, recent studies have demonstrated that therapeutic outcomes with specific chemotherapeutic agents (e.g. anthracyclines) correlate strongly with their ability to induce a process of immunogenic cell death (ICD) in cancer cells. This process generates a series of signals that stimulate the immune system to recognize and clear tumor cells. Extensive studies have revealed that chemotherapy-induced ICD occurs via the exposure/release of calreticulin (CALR), ATP, chemokine (C–X–C motif) ligand 10 (CXCL10) and high mobility group box 1 (HMGB1). This review provides an in-depth look into the concepts and mechanisms underlying CALR exposure, activation of the Toll-like receptor 3/IFN/CXCL10 axis, and the release of ATP and HMGB1 from dying cancer cells. Factors that influence the impact of ICD in clinical studies and the design of therapies combining chemotherapy with immunotherapy are also discussed.

Phase 1 studies of central memory-derived CD19 CAR T-cell therapy following autologous HSCT in patients with B-cell NHL

Myeloablative autologous hematopoietic stem cell transplantation (HSCT) is a mainstay of therapy for relapsed intermediate-grade B-cell non-Hodgkin lymphoma (NHL); however, relapse rates are high. In phase 1 studies designed to improve long-term remission rates, we administered adoptive T-cell immunotherapy after HSCT, using ex vivo-expanded autologous central memory-enriched T cells (TCM) transduced with lentivirus expressing CD19-specific chimeric antigen receptors (CARs). We present results from 2 safety/feasibility studies, NHL1 and NHL2, investigating different T-cell populations and CAR constructs. Engineered TCM-derived CD19 CAR T cells were infused 2 days after HSCT at doses of 25 to 200 × 10(6) in a single infusion. In NHL1, 8 patients safely received T-cell products engineered from enriched CD8(+) TCM subsets, expressing a first-generation CD19 CAR containing only the CD3ζ endodomain (CD19R:ζ). Four of 8 patients (50%; 95% confidence interval [CI]: 16-84%) were progression free at both 1 and 2 years. In NHL2, 8 patients safely received T-cell products engineered from enriched CD4(+) and CD8(+) TCM subsets and expressing a second-generation CD19 CAR containing the CD28 and CD3ζ endodomains (CD19R:28ζ). Six of 8 patients (75%; 95% CI: 35-97%) were progression free at 1 year. The CD4(+)/CD8(+) TCM-derived CD19 CAR T cells (NHL2) exhibited improvement in expansion; however, persistence was ≤28 days, similar to that seen by others using CD28 CARs. Neither cytokine release syndrome nor delayed hematopoietic engraftment was observed in either trial. These data demonstrate the safety and feasibility of CD19 CAR TCM therapy after HSCT. Trials were registered at www.clinicaltrials.gov as #NCT01318317 and #NCT01815749.

Requirement of interleukin 7 signaling for anti-tumor immune response under lymphopenic conditions in a murine lung carcinoma model

Induction of lymphopenia before adoptive transfer of T cells was followed by lymphopenia-induced proliferation (LIP) and generated a potent anti-tumor immune response in rodents and in a clinical setting. Previously, we reported that CD28 signaling is essential for the differentiation of functional effector cytotoxic T lymphocytes (CTLs) under lymphopenic conditions and sequential LIP of T cells. In this study, to clarify the correlation between LIP and the anti-tumor effect, LIP was inhibited with interleukin 7 (IL7) receptor blockade at various stages, and the anti-tumor effect then assessed. We confirmed that IL7 signaling at the start of LIP is crucial for the anti-tumor immune response. In contrast, continuous IL7 signaling was not required for tumor regression, although LIP of naïve CD8+ T cells is usually regulated by IL7. The expansion and migration of CTLs in lymphopenic hosts depend on IL7 signaling during the induction phase. Here, we propose that IL7 signaling and subsequent LIP of T cells have distinct roles in the induction of T cell immunity during lymphopenia.

Toll-like receptor agonist therapy can profoundly augment the antitumor activity of adoptively transferred CD8(+) T cells without host preconditioning

Background

Lymphodepletion enhances adoptive T cell transfer (ACT) therapy by activating the innate immune system via microbes released from the radiation-injured gut. Microbial components, such as LPS, are key mediators of total body irradiation (TBI) enhancement, but our ability to strategically use these toll-like receptor (TLR) agonists to bolster the potency of T cell-based therapies for cancer remains elusive. Herein, we used TLR4 agonist LPS as a tool to address how and when to use TLR agonists to effectively improve cancer immunotherapy.

Methods

To determine the mechanisms of how innate immune activation via lymphodepletion potentiated antitumor T cell immunity, we utilized the pmel-1 melanoma mouse model. B16F10-bearing mice were preconditioned with 5Gy TBI and given a tripartite ACT therapy (consisting of transferred pmel-1 CD8⁺ T cells, vaccination with fowlpox encoding gp100, and IL-2) along with TLR4 agonist LPS. The timing of LPS administration and the requirement of individual components of the tripartite therapy were evaluated based on tumor growth and the phenotype of recovered splenocytes by flow cytometry. We also evaluated the role of non-toxic and clinically used TLR4 and TLR9 agonists—monophosphoryl lipid A (MPL) and CpG Oligodeoxynucleotide (CpG ODN), respectively— for ACT therapy.

Results

Here we report that while exogenous administration of LPS was able to enhance adoptively transferred CD8⁺ T cells’ tumor destruction, LPS treatment alone did not replace individual components of the tripartite ACT regimen, or obviate TBI. Moreover, we found that sequentially administering LPS during or one day prior to ACT therapy compromised tumor regression. In contrast, administering LPS after ACT potentiated the antitumor effectiveness of the regimen, thereby supporting the expansion of transferred tumor-specific CD8⁺ T cells over host CD4⁺ T cells. We also found that non-toxic TLR agonists MPL and CpG potentiated the antitumor activity of infused CD8⁺ T cells. Finally, TBI was no longer needed to regress tumors in mice who were depleted of host CD4⁺ T cells, given a tripartite ACT regimen and then treated with low dose LPS.

Conclusions

Collectively, our results identify how and when to administer TLR agonists to augment T cell-based immunotherapy in the absence or presence of host preconditioning for treatment of advanced malignancies. Our findings have clinical implications for the design of next generation immune-based therapies for patients with cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-016-0110-8) contains supplementary material, which is available to authorized users.

Synthetic biology in cell-based cancer immunotherapy

The adoptive transfer of genetically engineered T cells with cancer-targeting receptors has shown tremendous promise for eradicating tumors in clinical trials. This form of cellular immunotherapy presents a unique opportunity to incorporate advanced systems and synthetic biology approaches to create cancer therapeutics with novel functions. We first review the development of synthetic receptors, switches, and circuits to control the location, duration, and strength of T cell activity against tumors. In addition, we discuss the cellular engineering and genome editing of host cells (or the chassis) to improve the efficacy of cell-based cancer therapeutics, and to reduce the time and cost of manufacturing.

Harnessing the Microbiome to Enhance Cancer Immunotherapy

The microbiota plays a key role in regulating the innate and adaptive immune system. Herein, we review the immunological aspects of the microbiota in tumor immunity in mice and man, with a focus on toll-like receptor (TLR) agonists, vaccines, checkpoint modulators, chemotherapy, and adoptive T cell transfer (ACT) therapies. We propose innovative treatments that may safely harness the microbiota to enhance T cell-based therapies in cancer patients. Finally, we highlight recent developments in tumor immunotherapy, particularly novel ways to modulate the microbiome and memory T cell responses to human malignancies.

Dendritic Cells in Irradiated Mice Trigger the Functional Plasticity and Antitumor Activity of Adoptively Transferred Tc17 Cells via IL12 Signaling

PURPOSE

The adoptive cell transfer (ACT) of CD8(+) T cells is a promising treatment for advanced malignancies. Lymphodepletion before ACT enhances IFNγ(+)CD8(+) T cell (Tc0)-mediated tumor regression. Yet, how lymphodepletion regulates the function and antitumor activity of IL17A(+)CD8(+) T cells (Tc17) is unknown.

EXPERIMENTAL DESIGN

To address this question, pmel-1 CD8(+) T cells were polarized to secrete either IL17A or IFNγ. These subsets were then infused into mice with B16F10 melanoma that were lymphoreplete [no total body irradiation (TBI)], or lymphodepleted with nonmyeloablative (5 Gy) or myeloablative (9 Gy with hematopoietic stem cell transplantation) TBI. The activation of innate immune cells and function of donor T-cell subsets were monitored in recipient mice.

RESULTS

Tc17 cells regress melanoma in myeloablated mice to a greater extent than in lymphoreplete or nonmyeloablated mice. TBI induced functional plasticity in Tc17 cells, causing conversion from IL17A to IFNγ producers. Additional investigation revealed that Tc17 plasticity and antitumor activity were mediated by IL12 secreted by irradiated host dendritic cells (DC). Neutralization of endogenous IL12 reduced the antitumor activity of Tc17 cells in myeloablated mice, whereas ex vivo priming with IL12 enhanced their capacity to regress melanoma in nonmyeloablated animals. This, coupled with exogenous administration of low-dose IL12, obviated the need for host preconditioning, creating curative responses in nonirradiated mice.

CONCLUSIONS

Our findings indicate that TBI-induced IL12 augments Tc17 cell-mediated tumor immunity and underline the substantial implications of in vitro preparation of antitumor Tc17 cells with IL12 in the design of T-cell immunotherapies.

Beyond consolidation: auto-SCT and immunotherapy for plasma cell myeloma

Autologous hematopoietic cell transplantation (auto-HCT) is the standard consolidation therapy for plasma cell myeloma patients following induction therapy. Auto-HCT improves disease-free survival (DFS), but is generally not curative. The allogeneic HCT experience demonstrated that T-cell immunotherapy can confer long-term DFS. Preclinical and clinical data indicate that myeloma-associated Ags elicit humoral and cellular immune responses (IRs) in myeloma patients. These findings strongly suggest that the immunotherapeutic strategies, including immune checkpoint inhibitors, therapeutic cancer vaccines and adoptive cellular therapies, are promising avenues of clinical research that may be most applicable in the minimal residual disease state following auto-HCT. These strategies are designed to prime or augment antimyeloma IRs and promote a 'host-vs-myeloma' effect that may result in durable DFS. Innovative clinical trials investigating immune checkpoint inhibitors and cancer vaccines have demonstrated that robust immunity against myeloma-associated Ags can be elicited in the setting of auto-HCT. A diverse array of immunotherapeutic strategies have entered clinical trials in myeloma, including PD-1/PD-L1 inhibitors, DC/myeloma cell fusion vaccines and adoptive chimeric Ag receptor T-cell therapy, and further investigation of combinations of immunologic and pharmaceutical agents are expected in the near future. In this review, we will discuss the preclinical data supporting immunotherapy in auto-HCT for myeloma, clinical investigation of these strategies and the future prospects of immunotherapy in pursuit of the goal of curative therapy.

Mouse model for pre-clinical study of human cancer immunotherapy

This unit describes protocols for developing tumors in mice, including subcutaneous growth, pulmonary metastases of B16 melanoma, and spontaneous melanoma in B-Raf V600E/PTEN deletion transgenic mouse models. Two immunization methods to prevent B16 tumor growth are described using B16.GM-CSF and recombinant vaccinia virus. A therapeutic approach is also included that uses adoptive transfer of tumor antigen-specific T cells. Methods including CTL induction, isolation, testing, and genetic modification of mouse T cells for adoptive transfer by using retrovirus-expressing genes of interest are provided. Additional sections, including growing B16 melanoma, enumerating pulmonary metastases, tumor imaging technique, and use of recombinant viruses for vaccination, are discussed together with safety concerns.