Redirection of CD4+ and CD8+ T lymphocytes via an anti-CD3 × anti-CD19 bi-specific antibody combined with cytosine arabinoside and the efficient lysis of patient-derived B-ALL cells

Enhancement of Microglia Functions by Developed Nano-Immuno-Synergist to Ameliorate Immunodeficiency for Malignant Glioma Treatment

Resident microglia are key factors in mediating immunity against brain tumors, but the microglia in malignant glioma are functionally impaired. Little immunotherapy is explored to restore microglial function against glioma. Herein, oleanolic acid (OA) (microglia "restorer") and D PPA-1 peptide (immune checkpoint blockade) are integrated on a nano-immuno-synergist (D PAM@OA) to work coordinately. The self-assembled OA core is coated with macrophage membrane for efficient blood-brain barrier penetration and microglia targeting, on which D PPA-1 peptide is attached via acid-sensitive bonds for specific release in tumor microenvironment. With the enhanced accumulation of the dual drugs in their respective action sites, D PAM@OA effectively promotes the recruitment and activation of effector T cells by inhibiting aberrant activation of Signal transducer and activator of transcription (STAT-3) pathway in microglia, and assists activated effector T cells in killing tumor cells by blocking elevated immune checkpoint proteins in malignant glioma. Eventually, as adjuvant therapy, the rationally designed nano-immuno-synergist hinders malignant glioma progression and recurrence with or without temozolomide. The work demonstrates the feasibility of a nano-formulation for microglia-based immunotherapy, which may provide a new direction for the treatment of brain tumors.

A novel bivalent anti-c-MET/PD-1 bispecific antibody exhibits potent cytotoxicity against c-MET/PD-L1-positive colorectal cancer

Previously, we generated a novel bispecific antibody (BsAb) simultaneously targeting both c-MET and PD-1 (PDCD1), which can bridge T cells and c-MET positive tumor cells. However, the specific mechanisms and antitumor activities of the BsAb against c-MET/PD-L1 (CD274) positive colorectal cancer (CRC) is not completely understood. In this study, in addition to the tumor intrinsic mechanism investigation with molecular biology assay in vitro, a humanized mouse model was used to evaluate antitumor activity of the BsAb in vivo. The BsAb could inhibit c-MET/PD-L1+ CRC cell migration and show strong antitumor activity against HCT116 tumors in mice, potentially by inducing the degradation of c-MET protein in a dose and time-dependent manner. The BsAb could suppress the phosphorylation of c-MET downstream proteins GRB2-associated-binding protein 1 (Gab1) and focal adhesion kinase (FAK). Considering the tumor extrinsic mechanism, the BsAb may promote phagocytosis of macrophage. Furthermore, the level of plasma exosomal-c-MET/PD-L1 is able to distinguish CRC patients from healthy controls. In summary, the BsAb exhibited potent anti-tumor activities by two distinguished mechanisms: inhibition of c-MET signal transduction and promotion of macrophage-mediated phagocytosis. Our BsAb may provide a novel therapeutic agent for patients with c-MET/PD-L1+ CRC, and the status of exosomal-c-MET/PD-L1 can serve as a biomarker to predict responsiveness to treatment of our BsAb.

Binding domain on CD22 molecules contributing to the biological activity of T cell-engaging bispecific antibodies

CD22, as the B-cell malignancies antigen, has been targeted for immunotherapies through CAR-T cells, antibody-drug conjugates (ADCs) and immunotoxins via interaction of antibodies with binding domains on the receptor. We hypothesized that avidity and binding domain of antibody to target cells may have significant impact on the biological function in tumor immunotherapy, and T cell-engaging bispecific antibody (TCB) targeting CD22 could be used in the therapy of hematologic malignancies. So, to address the question, we utilized the information of six previously reported CD22 mAbs to generate CD22-TCBs with different avidity to different domains on CD22 protein. We found that the avidity of CD22-TCBs to protein was not consistent with the avidity to target cells, indicating that TCBs had different binding mode to the protein and cells. In vitro results indicated that CD22-TCBs mediated cytotoxicity depended on the avidity of antibodies to target cells rather than to protein. Moreover, distal binding domain of the antigen contributed to the avidity and biological activity of IgG-[L]-scfv-like CD22-TCBs. The T cells' proliferation, activation, cytotoxicity as well as cytokine release were compared, and G5/44 BsAb was selected for further in vivo assessment in anti-tumor activity. In vivo results demonstrated that CD22-TCB (G5/44 BsAb) significantly inhibited the tumors growth in mice. All these data suggested that CD22-TCBs could be developed as a promising candidate for B-cell malignancies therapy through optimizing the design with avidity and binding domain to CD22 target in consideration.

“A.B.C.” of Immunotherapy in Hematological Malignancies…Promise and Perils

The treatment landscape of hematological malignancies has been evolving at an extremely fast pace. Hematological malignancies are diverse and distinct from solid tumors. These constitute challenges, which are also unique opportunities for immunotherapy. The five categories of immunotherapies that have found success in the management of hematological malignancies are allogeneic hematopoietic stem cell transplant, monoclonal antibodies and innovative designs, immune checkpoint inhibitors, chimeric antigen receptor (CAR) T cells, and B cell targeting small immunomodulatory molecules. Allogeneic stem cell transplant rightly called our bluntest weapon is the oldest form of successful immunotherapy. Alternate donor transplants and improvement in supportive care have improved the scope of this immunotherapy option. Among monoclonal antibodies, rituximab forms the prototype on which over a dozen other antibodies have been developed. The bispecific T-cell engager (BiTE) blinatumomab engages cytotoxic CD3 T cells with CD19 acute lymphoblastic leukemia (ALL) cells, which is an effective treatment method for relapsed refractory ALL. Immune checkpoint inhibitors have established their role in hematological malignancies with high PD-L1 expression, including relapsed refractory Hodgkin's lymphoma and primary mediastinal B cell lymphoma (BCL). Small immunomodulatory drugs targeting the B cell receptor downstream signaling through BTK inhibitors, SYK inhibitors, PI3K inhibitors (idelalisib), and BCL-2 inhibitors (venetoclax), and immunomodulatory imide drugs (lenalidomide) have also emerged as exciting therapeutic avenues in immunotherapy. CAR T cells are one of the most exciting and promising forms of adoptive immunotherapy. CAR T cells are rightly called living drugs or serial killers to keep patients alive. CAR T cells are genetically engineered, autologous T cells that combine the cytotoxicity of T cells with the antigen-binding specificity of CARs. CARs are antigen-specific but major histocompatibility complex/human leukocyte antigen-independent. There are five approved CAR T cell products for the management of relapsed refractory leukemias, lymphoma, and multiple myeloma. The past and present of immunotherapy have been really exciting and the future looks incredibly promising. The challenges include widening the availability and affordability beyond specialized centers, identification of potentially predictive biomarkers of response, and experience in the management of complications of these novel agents. The combinational approach of multiple immunotherapies might be the way forward to complement the treatment strategies to harness the immune system and to improve survival with good quality of life.

Efficacy of Flotetuzumab in Combination with Cytarabine in Patient-Derived Xenograft Models of Pediatric Acute Myeloid Leukemia

Children with acute myeloid leukemia (AML) have a poor prognosis despite the intensification of chemotherapy. Future efforts to improve outcomes should focus on more precise targeting of leukemia cells. CD123, or IL3RA, is expressed on the surface of nearly all pediatric AML samples and is a high-priority target for immunotherapy. The efficacy of an investigational dual-affinity retargeting antibody (DART) molecule (CD123 × CD3; MGD006 or flotetuzumab) was assessed in two distinct patient-derived xenograft (PDX) models of pediatric AML. MGD006 simultaneously binds to CD123 on target cells and CD3 on effector T cells, thereby activating T cells and redirecting them to induce cytotoxicity in target cells. The concurrent treatment of cytarabine and MGD006 was performed to determine the effect of cytarabine on T-cell counts and MGD006 activity. Treatment with MGD006 along with an allogeneic human T-cell infusion to act as effector cells induced durable responses in both PDX models, with CD123 positivity. This effect was sustained in mice treated with a combination of MGD006 and cytarabine in the presence of T cells. MGD006 enhanced T-cell proliferation and decreased the burden of AML blasts in the peripheral blood with or without cytarabine treatment. These data demonstrate the efficacy of MGD006 in prolonging survival in pediatric AML PDX models in the presence of effector T cells and show that the inclusion of cytarabine in the treatment regimen does not interfere with MGD006 activity.

For whom the T cells troll? Bispecific T-cell engagers in glioblastoma

Glioblastoma is the the most common primary brain tumor in adults. Onset of disease is followed by a uniformly lethal prognosis and dismal overall survival. While immunotherapies have revolutionized treatment in other difficult-to-treat cancers, these have failed to demonstrate significant clinical benefit in patients with glioblastoma. Obstacles to success include the heterogeneous tumor microenvironment (TME), the immune-privileged intracranial space, the blood-brain barrier (BBB) and local and systemic immunosuppressions. Monoclonal antibody-based therapies have failed at least in part due to their inability to access the intracranial compartment. Bispecific T-cell engagers are promising antibody fragment-based therapies which can bring T cells close to their target and capture them with a high binding affinity. They can redirect the entire repertoire of T cells against tumor, independent of T-cell receptor specificity. However, the multiple challenges posed by the TME, immune privilege and the BBB suggest that a single agent approach may be insufficient to yield durable, long-lasting antitumor efficacy. In this review, we discuss the mechanism of action of T-cell engagers, their preclinical and clinical developments to date. We also draw comparisons with other classes of multispecific antibodies and potential combinations using these antibody fragment therapies.

A Novel Bispecific Antibody Targeting CD3 and Lewis Y with Potent Therapeutic Efficacy against Gastric Cancer

Lewis Y antigen, a glycan highly expressed on most epithelial cancers, was targeted for cancer treatment but lacked satisfactory results in some intractable and refractory cancers. Thus, it is highly desirable to develop an effective therapy against these cancers, hopefully based on this target. In this work, we constructed a novel T cell-engaging bispecific antibody targeting Lewis Y and CD3 (m3s193 BsAb) with the IgG-[L]-scfv format. In vitro activity of m3s193 BsAb was evaluated by affinity assay to target cells, cytotoxicity assay, cytokines releasing assay, and T cells proliferation and recruiting assays. Anti-tumor activity against gastric cancer was evaluated in vivo by subcutaneous huPBMCs/tumor cells co-grafting model and huPBMCs intravenous injecting model. In vitro, m3s193 BsAb appeared to have a high binding affinity to Lewis Y positive cells and Jurkat cells. The BsAb showed stronger activity than its parent mAb in T cell recruiting, activation, proliferation, cytokine release, and cytotoxicity. In vivo, m3s193 BsAb not only demonstrated higher therapeutic efficacy in the huPBMCs/tumor co-grafting gastric carcinoma model than the parent mAb but also eliminated tumors in the model of intravenous injection with huPBMCs. Strong anti-tumor activity of m3s193 BsAb revealed that Lewis Y could be targeted in T cell-engaging BsAb for gastric cancer therapy.

Strategic enhancement of immune checkpoint inhibition in refractory Colorectal Cancer: Trends and future prospective

Colorectal cancer (CRC), known as a frequently fatal disease, ranking as the third most common malignancy, is the second leading cause of cancer related mortality worldwide. Metastases are common in CRC patients which account for approximately 25% of the patients at diagnosis, 50% of patients during treatment which is associated closely with CRC mortality. Conventional therapies such as surgery, chemotherapy, and radiotherapy are standards of care for the treatment of CRC patients. However, primary tumor recurrence and secondary disease in patients receiving standard of care treatment modalities occur in 50% of patients so that new treatment modalities are needed. Immune checkpoint inhibition (ICI) has transformed the management of patients suffered from metastatic CRC (mCRC) with mismatch repair deficiency (dMMR) and microsatellite instability (MSI) -high (MSI-H) while manifests ineffectiveness in preserved mismatch repair (pMMR) or microsatellite stable (MSS) "cold" tumors which makes up the majority (95%) of mCRC. In this review, we mainly lay emphasis on the development of combinations in therapy strategies with ICIs with other immune based treatment approaches to increase the intra-tumoral immune response and render tumors 'immune-reactive', thereby increasing the efficacy of tumor immunotherapy.

Breast cancer immunotherapy: Current and novel approaches

The crucial role of the immune system in the progression/regression of breast cancer (BC) should always be taken into account. Various immunotherapy approaches have been investigated for BC, including tumor-targeting antibodies (bispecific antibodies), adoptive T cell therapy, vaccines, and immune checkpoint blockade such as anti-PD-1. In addition, a combination of conventional chemotherapy and immunotherapy approaches contributes to improving patients' overall survival rates. Although encouraging outcomes have been reported in most clinical trials of immunotherapy, some obstacles should still be resolved in this regard. Recently, personalized immunotherapy has been proposed as a potential complementary medicine with immunotherapy and chemotherapy for overcoming BC. Accordingly, this review discusses the brief association of these methods and future directions in BC immunotherapy.

Woodchuck Hepatitis Virus Post-Transcriptional Regulation Element (WPRE) Promotes Anti-CD19 BiTE Expression in Expi293 Cells

Background:

Bispecific antibodies represent an important class of mAbs, with great therapeutic potentials due to their ability to target simultaneously two distinct epitopes. The generation of functional bispecific antibodies with the highest possible yields is particularly critical for the production of these compounds on industrial scales. Anti- CD3 × CD19 bsAb is a bispecific T-cell engager (BiTE) currently used for treating ALL. Herein, we have tried to optimize the expression level of this antibody in mammalian hosts.

Methods:

WPRE sequence was incorporated at the 3’ end of the expression cassette. This modification resulted in a notable about two-fold increase in the expression of the bsAb in the Expi293 cell line.

Results & Conclusion:

Follow-up flow cytometry analysis demonstrated the binding properties of the produced antibody at acceptable levels, and in vitro bioactivity assays showed that this product is potent enough for targeting and destroying CD19-positive cells. Our findings show that WPRE enhances the expression of this type of bispecific mAbs in HEK-293 family cell lines. This approach can be used in biopharma industry for the mass production of anti-CD3 × CD19 bispecific antibody.

In Situ Programming of CAR T Cells

Gene therapy makes it possible to engineer chimeric antigen receptors (CARs) to create T cells that target specific diseases. However, current approaches require elaborate and expensive protocols to manufacture engineered T cells ex vivo, putting this therapy beyond the reach of many patients who might benefit. A solution could be to program T cells in vivo. Here, we evaluate the clinical need for in situ CAR T cell programming, compare competing technologies, review current progress, and provide a perspective on the long-term impact of this emerging and rapidly flourishing biotechnology field.

A Cross-Protective Vaccine Against 4b and 1/2b Listeria monocytogenes

Listeria monocytogenes (Lm) is a foodborne zoonotic pathogen that causes listeriosis with a mortality rate of 20-30%. Serovar 4b and 1/2b isolates account for most of listeriosis outbreaks, however, no listeriosis vaccine is available for either prophylactic or therapeutic use. Here, we developed a triple-virulence-genes deletion vaccine strain, and evaluated its safety, immunogenicity, and cross-protective efficiency. The virulence of NTSNΔactA/plcB/orfX was reduced 794-folds compared with the parental strain. Additionally, it was completely eliminated in mice at day 7 post infection and no obvious pathological changes were observed in the organs of mice after prime-boost immunization for 23 days. These results proved that the safety of the Lm vaccine strain remarkably increased. More importantly, the NTSNΔactA/plcB/orfX strain stimulated higher anti-Listeriolysin O (LLO) antibodies, induced significantly higher expression of IFN-γ, TNF-α, IL-17, and IL-6 than the control group, and afforded 100% protection against serovar 4b and 1/2b challenges. Taken together, our research demonstrates that the triple-genes-deletion vaccine has high safety, can elicit strong Th1 type immune response, and affords efficient cross-protection against two serovar Lm strains. It is a promising vaccine for prevention of listeriosis.

In vitro-transcribed antigen receptor mRNA nanocarriers for transient expression in circulating T cells in vivo

Engineering chimeric antigen receptors (CAR) or T cell receptors (TCR) helps create disease-specific T cells for targeted therapy, but the cost and rigor associated with manufacturing engineered T cells ex vivo can be prohibitive, so programing T cells in vivo may be a viable alternative. Here we report an injectable nanocarrier that delivers in vitro-transcribed (IVT) CAR or TCR mRNA for transiently reprograming of circulating T cells to recognize disease-relevant antigens. In mouse models of human leukemia, prostate cancer and hepatitis B-induced hepatocellular carcinoma, repeated infusions of these polymer nanocarriers induce sufficient host T cells expressing tumor-specific CARs or virus-specific TCRs to cause disease regression at levels similar to bolus infusions of ex vivo engineered lymphocytes. Given their ease of manufacturing, distribution and administration, these nanocarriers, and the associated platforms, could become a therapeutic for a wide range of diseases.

Ex vivo engineering of antigen-specific T cells has shown therapeutic efficacy but can be costly and scarce. Here the authors show that in vitro-transcribed antigen receptor mRNA packaged in nanocarriers can directly induce, in vivo, transient their expression in circulating T cells to provide therapeutic effects in mouse models of cancer or viral infection.

Development and clinical application of bispecific antibody in the treatment of colorectal cancer

INTRODUCTION

Treatment of colorectal cancer as one of the most commonly diagnosed and a frequent cause of cancer-related deaths is of great challenges in health-related issues.

AREAS COVERED

Immunotherapy is the fourth pillar of cancer treatment which provides more novel therapeutic options with expanding investigational potentials. One of the modalities in immunotherapy is the use of bispecific antibodies. Despite demonstrating many promising roles, it still needs more advanced studies to identify the actual pros and cons. In this review, the application of bispecific antibody in the treatment of colorectal cancer has been explained, based on preclinical and clinical studies. The literature search was conducted mainly through PubMed in June and September 2019.

EXPERT OPINION

Bispecific antibody is in its early stages in colorectal cancer treatment, requiring modern technologies in manufacturing, better biomarkers and more specific target antigens, more studies on individual genetic variations, and conducting later phase clinical trials and systematic reviews to achieve better survival benefits.

Bispecific T-cell engagers: Towards understanding variables influencing the in vitro potency and tumor selectivity and their modulation to enhance their efficacy and safety

Bispecific molecules redirecting the cytotoxicity of T-cells are a growing class of therapeutics with numerous molecules being tested in clinical trials. However, it has been a long way since the proof of concept studies in the mid 1980's. In the process we have learnt about the impact of different variables related to the bispecific molecule and the target antigen on the potency of this type of drugs. This work reviews the insights gained and how that knowledge has been used to design more potent bispecific T-cell engagers. The more recent advancement of antibodies with this modality into safety studies in non-human primates and as well as in clinical studies has revealed potential toxicity liabilities for the mode of action. Modifications in existing antibody formats and new experimental molecules designed to mitigate these problems are discussed.

T cell engaging bispecific antibody (T-BsAb): From technology to therapeutics

Harnessing the power of the human immune system to treat cancer is the essence of immunotherapy. Monoclonal antibodies engage the innate immune system to destroy targeted cells. For the last 30years, antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity have been the main mechanisms of anti-tumor action of unconjugated antibody drugs. Efforts to exploit the potentials of other immune cells, in particular T cells, culminated in the recent approval of two T cell engaging bispecific antibody (T-BsAb) drugs, thereby stimulating new efforts to accelerate similar platforms through preclinical and clinical trials. In this review, we have compiled the worldwide effort in exploring T cell engaging bispecific antibodies. Our special emphasis is on the lessons learned, with the hope to derive insights in this fast evolving field with tremendous clinical potential.

Recent advances in cancer immunology and immunology-based anticancer therapies

Cancer immunotherapies offer promise for cure of cancer with specificity and minimal toxicity. Recent developments in cancer immunology have led to the better understanding of role of immune regulatory mechanisms in cancer. There is rapid progress in this field in the last few years. Several clinical studies report the efficacy of immunotherapies for treating cancer. The immunology-based anticancer therapies have shown better safety profiles in clinic as compared to other chemotherapeutic agents, thus increasing interest in this area. This review summarizes recent advances in cancer immunology and discusses tumor microenvironment and immunology-based anticancer therapies, including vaccines and therapies targeting immune checkpoints.

Recent advances of bispecific antibodies in solid tumors

Cancer immunotherapy is the most exciting advancement in cancer therapy. Similar to immune checkpoint blockade and chimeric antigen receptor T cell (CAR-T), bispecific antibody (BsAb) is attracting more and more attention as a novel strategy of antitumor immunotherapy. BsAb not only offers an effective linkage between therapeutics (e.g., immune effector cells, radionuclides) and targets (e.g., tumor cells) but also simultaneously blocks two different oncogenic mediators. In recent decades, a variety of BsAb formats have been generated. According to the structure of Fc domain, BsAb can be classified into two types: IgG-like format and Fc-free format. Among these formats, bispecific T cell engagers (BiTEs) and triomabs are commonly investigated. BsAb has achieved an exciting breakthrough in hematological malignancies and promising outcome in solid tumor as showed in various clinical trials. In this review, we focus on the preclinical experiments and clinical studies of epithelial cell adhesion molecule (EpCAM), human epidermal growth factor receptor (HER) family, carcinoembryonic antigen (CEA), and prostate-specific membrane antigen (PSMA) related BsAbs in solid tumors, as well as discuss the challenges and corresponding approaches in clinical application.

Novel immunotherapies for adult patients with B-lineage acute lymphoblastic leukemia

The past decade witnessed the rapid development of adult B-lineage acute lymphoblastic leukemia (ALL) treatment. Beyond the development of chemotherapy regimens, immunotherapy is starting a new era with unprecedented complete remission (CR) rate. Targeting B-lineage-specific surface markers such as CD19, CD20, CD22, or CD52, immunotherapy has been demonstrating promising clinical results. Among the immunotherapeutic methods, naked monoclonal antibodies (mAbs), antibody-drug conjugate (ADC), bispecific T cell engager (BiTE), and chimeric antigen receptor (CAR) T cells are the main types. In this review, we will examine the emerging preclinical and clinical development on (1) anti-CD20 naked mAbs rituximab, ofatumumab, and obinutuzumab; (2) anti-CD19 ADCs SAR3419 and SGN-CD19A and anti-CD19 BiTE blinatumomab; (3) anti-CD22 naked mAb epratuzumab and anti-CD22 ADC inotuzumab ozogamicin; (4) anti-CD52 naked mAb alemtuzumab; and (5) anti-CD19 CAR T cells. We will discuss their efficacy, adverse effects, as well as future development.

Syk inhibitors in clinical development for hematological malignancies

Spleen tyrosine kinase (Syk) is a cytosolic non-receptor protein tyrosine kinase (PTK) and is mainly expressed in hematopoietic cells. Syk was recognized as a critical element in the B-cell receptor signaling pathway. Syk is also a key component in signal transduction from other immune receptors like Fc receptors and adhesion receptors. Several oral Syk inhibitors including fostamatinib (R788), entospletinib (GS-9973), cerdulatinib (PRT062070), and TAK-659 are being assessed in clinical trials. The second generation compound, entospletinib, showed promising results in clinical trials against B-cell malignancies, mainly chronic lymphoid leukemia. Syk inhibitors are being evaluated in combination regimens in multiple malignancies.

Advances in combination therapy of lung cancer: Rationales, delivery technologies and dosage regimens

Lung cancer is a complex disease caused by a multitude of genetic and environmental factors. The progression of lung cancer involves dynamic changes in the genome and a complex network of interactions between cancer cells with multiple, distinct cell types that form tumors. Combination therapy using different pharmaceuticals has been proven highly effective due to the ability to affect multiple cellular pathways involved in the disease progression. However, the currently used drug combination designs are primarily based on empirical clinical studies, and little attention has been given to dosage regimens, i.e. how administration routes, onsets, and durations of the combinations influence the therapeutic outcome. This is partly because combination therapy is challenged by distinct physicochemical properties and in vivo pharmacokinetics/pharmacodynamics of the individual pharmaceuticals, including small molecule drugs and biopharmaceuticals, which make the optimization of dosing and administration schedule challenging. This article reviews the recent advances in the design and development of combinations of pharmaceuticals for the treatment of lung cancer. Focus is primarily on rationales for the selection of specific combination therapies for lung cancer treatment, and state of the art of delivery technologies and dosage regimens for the combinations, tested in preclinical and clinical trials.

Immunotherapy in hematologic malignancies: past, present, and future

The field of immunotherapy in cancer treatments has been accelerating over recent years and has entered the forefront as a leading area of ongoing research and promising therapies that have changed the treatment landscape for a variety of solid malignancies. Prior to its designation as the Science Breakthrough of the Year in 2013, cancer immunotherapy was active in the treatment of hematologic malignancies. This review provides a broad overview of the past, present, and potential future of immunotherapy in hematologic malignancies.

Mesenchymal stromal cells as vehicles of tetravalent bispecific Tandab (CD3/CD19) for the treatment of B cell lymphoma combined with IDO pathway inhibitor D-1-methyl-tryptophan

Background

Although blinatumomab, a bispecific T cell engaging antibody, exhibits high clinical response rates in patients with relapsed or refractory B-precursor acute lymphoblastic leukemia (B-ALL) and B cell non-Hodgkin’s lymphoma (B-NHL), it still has some limitations because of its short half-life. Mesenchymal stromal cells (MSCs) represent an attractive approach for delivery of therapeutic agents to cancer sites owing to their tropism towards tumors, but their immunosuppression capabilities, especially induced by indoleamine 2,3-dioxygenase (IDO), should also be taken into consideration.

Methods

Human umbilical cord-derived MSCs (UC-MSCs) were genetically modified to secrete Tandab (CD3/CD19), a tetravalent bispecific tandem diabody with two binding sites for CD3 and two for CD19. The tropism of MSCs towards Raji cells in vitro was determined by migration assays, and the homing property of MSCs in vivo was analyzed with firefly luciferase-labeled MSCs (MSC-Luc) by bioluminescent imaging (BLI). The cytotoxicity of T cells induced by MSC-secreting Tandab (CD3/CD19) was detected in vitro and in vivo in combination with d-1-methyl-tryptophan (D-1MT), an IDO pathway inhibitor.

Results

The purified Tandab (CD3/CD19) was functional with high-binding capability both for CD3-positive cells and CD19-positive cells and was able to induce specific lysis of CD19-positive cell lines (Raji, Daudi, and BJAB) in the presence of T cells. Additionally, results from co-culture killing experiments demonstrated that Tandab (CD3/CD19) secreted from MSCs was also effective. Then, we confirmed that D-1MT could enhance the cytotoxicity of T cells triggered by MSC-Tandab through reversing T cell anergy with down-regulation of CD98 and Jumonji and restoring the proliferation capacity of T cells. Furthermore, MSC-Luc could selectively migrate to tumor site in a BALB/c nude mouse model with Raji cells. And mice injected with MSC-Tandab in combination with D-1MT significantly inhibited the tumor growth.

Conclusions

These results suggest that UC-MSCs releasing Tandab (CD3/CD19) is an efficient therapeutic tool for the treatment of B cell lymphoma when combined with D-1MT.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0397-z) contains supplementary material, which is available to authorized users.

New development in CAR-T cell therapy

Chimeric antigen receptor (CAR)-engineered T cells (CAR-T cells) have yielded unprecedented efficacy in B cell malignancies, most remarkably in anti-CD19 CAR-T cells for B cell acute lymphoblastic leukemia (B-ALL) with up to a 90% complete remission rate. However, tumor antigen escape has emerged as a main challenge for the long-term disease control of this promising immunotherapy in B cell malignancies. In addition, this success has encountered significant hurdles in translation to solid tumors, and the safety of the on-target/off-tumor recognition of normal tissues is one of the main reasons. In this mini-review, we characterize some of the mechanisms for antigen loss relapse and new strategies to address this issue. In addition, we discuss some novel CAR designs that are being considered to enhance the safety of CAR-T cell therapy in solid tumors.

Synergism between the mTOR inhibitor rapamycin and FAK down-regulation in the treatment of acute lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is an aggressive malignant disorder of lymphoid progenitor cells in both children and adults. Although improvements in contemporary therapy and development of new treatment strategies have led to dramatic increases in the cure rate in children with ALL, the relapse rate remains high and the prognosis of relapsed childhood ALL is poor. Molecularly targeted therapies have emerged as the leading treatments in cancer therapy. Multi-cytotoxic drug regimens have achieved success, yet many studies addressing targeted therapies have focused on only one single agent. In this study, we attempted to investigate whether the effect of the mammalian target of rapamycin (mTOR) inhibitor rapamycin is synergistic with the effect of focal adhesion kinase (FAK) down-regulation in the treatment of ALL.

Methods

The effect of rapamycin combined with FAK down-regulation on cell proliferation, the cell cycle, and apoptosis was investigated in the human precursor B acute lymphoblastic leukemia cells REH and on survival time and leukemia progression in a non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse model.

Results

When combined with FAK down-regulation, rapamycin-induced suppression of cell proliferation, G₀/G₁ cell cycle arrest, and apoptosis were significantly enhanced. In addition, REH cell-injected NOD/SCID mice treated with rapamycin and a short-hairpin RNA (shRNA) to down-regulate FAK had significantly longer survival times and slower leukemia progression compared with mice injected with REH-empty vector cells and treated with rapamycin. Moreover, the B-cell CLL/lymphoma-2 (BCL-2) gene family was shown to be involved in the enhancement, by combined treatment, of REH cell apoptosis.

Conclusions

FAK down-regulation enhanced the in vitro and in vivo inhibitory effects of rapamycin on REH cell growth, indicating that the simultaneous targeting of mTOR- and FAK-related pathways might offer a novel and powerful strategy for treating ALL.

CCR9 in cancer: oncogenic role and therapeutic targeting

Cancer is currently one of the leading causes of death worldwide and is one of the most challenging major public health problems. The main challenges faced by clinicians in the management and treatment of cancer mainly arise from difficulties in early diagnosis and the emergence of tumor chemoresistance and metastasis. The structures of chemokine receptor 9 (CCR9) and its specific ligand chemokine ligand 25 (CCL25) have been elucidated, and, interestingly, a number of studies have demonstrated that CCR9 is a potential tumor biomarker in diagnosis and therapy, as it has been found to be highly expressed in a wide range of cancers. This expression pattern suggests that CCR9 may participate in many important biological activities involved in cancer progression. Researchers have shown that CCR9 that has been activated by its specific ligand CCL25 can interact with many signaling pathways, especially those involved in tumor chemoresistance and metastasis. This review, therefore, focuses on CCR9 induction activity and summarizes what is currently known regarding its role in cancers and its potential application in tumor-targeted therapy.

Bispecific antibodies and their applications

Bispecific antibodies (BsAbs) recognize two different epitopes. This dual specificity opens up a wide range of applications, including redirecting T cells to tumor cells, blocking two different signaling pathways simultaneously, dual targeting of different disease mediators, and delivering payloads to targeted sites. The approval of catumaxomab (anti-EpCAM and anti-CD3) and blinatumomab (anti-CD19 and anti-CD3) has become a major milestone in the development of bsAbs. Currently, more than 60 different bsAb formats exist, some of them making their way into the clinical pipeline. This review summarizes diverse formats of bsAbs and their clinical applications and sheds light on strategies to optimize the design of bsAbs.