Bispecific antibodies for multiple myeloma: past, present and future

Despite the development of various therapeutic agents, multiple myeloma remains incurable. Recently, T-cell redirected immunotherapy has become a promising strategy for the treatment of refractory myeloma. Clinical trials using chimeric antigen receptor (CAR)-T cells and bispecific antibodies have demonstrated successful anti-myeloma responses in triple-class-refractory patients. However, unique and unwanted immune effects associated with on-target/off-target reactivity of activated immune cells need to be considered and properly managed. This review summarizes recent advances in bispecific antibodies for the treatment of refractory myeloma. It outlines the history of their development, along with a discussion of their mechanisms of action and their current and potential future role in myeloma therapy. As more evidence emerges to inform the timing of CAR-T-cell therapy, the results of clinical trials and off-the-shelf nature of bispecifics also suggest the timing of their treatment. These findings will promote further development and application of bispecifics for refractory myeloma in combination with other appropriate agents.

Lysyl oxidase-like 4 promotes the invasiveness of triple-negative breast cancer cells by orchestrating the invasive machinery formed by annexin A2 and S100A11 on the cell surface

Background

Our earlier research revealed that the secreted lysyl oxidase-like 4 (LOXL4) that is highly elevated in triple-negative breast cancer (TNBC) acts as a catalyst to lock annexin A2 on the cell membrane surface, which accelerates invasive outgrowth of the cancer through the binding of integrin-β1 on the cell surface. However, whether this machinery is subject to the LOXL4-mediated intrusive regulation remains uncertain.

Methods

Cell invasion was assessed using a transwell-based assay, protein-protein interactions by an immunoprecipitation-Western blotting technique and immunocytochemistry, and plasmin activity in the cell membrane by gelatin zymography.

Results

We revealed that cell surface annexin A2 acts as a receptor of plasminogen via interaction with S100A10, a key cell surface annexin A2-binding factor, and S100A11. We found that the cell surface annexin A2/S100A11 complex leads to mature active plasmin from bound plasminogen, which actively stimulates gelatin digestion, followed by increased invasion.

Conclusion

We have refined our understanding of the role of LOXL4 in TNBC cell invasion: namely, LOXL4 mediates the upregulation of annexin A2 at the cell surface, the upregulated annexin 2 binds S100A11 and S100A10, and the resulting annexin A2/S100A11 complex acts as a receptor of plasminogen, readily converting it into active-form plasmin and thereby enhancing invasion.

Phosphorylated SARM1 is involved in the pathological process of rotenone-induced neurodegeneration

Sterile alpha and Toll/interleukin receptor motif-containing protein 1 (SARM1) is a NAD+ hydrolase that plays a key role in axonal degeneration and neuronal cell death. We reported that c-Jun N-terminal kinase (JNK) activates SARM1 through phosphorylation at Ser-548. The importance of SARM1 phosphorylation in the pathological process of Parkinson's disease (PD) has not been determined. We thus conducted the present study by using rotenone (an inducer of PD-like pathology) and neurons derived from induced pluripotent stem cells (iPSCs) from healthy donors and a patient with familial PD PARK2 (FPD2). The results showed that compared to the healthy neurons, FPD2 neurons were more vulnerable to rotenone-induced stress and had higher levels of SARM1 phosphorylation. Similar cellular events were obtained when we used PARK2-knockdown neurons derived from healthy donor iPSCs. These events in both types of PD-model neurons were suppressed in neurons treated with JNK inhibitors, Ca2+-signal inhibitors, or by a SARM1-knockdown procedure. The degenerative events were enhanced in neurons overexpressing wild-type SARM1 and conversely suppressed in neurons overexpressing the SARM1-S548A mutant. We also detected elevated SARM1 phosphorylation in the midbrain of PD-model mice. The results indicate that phosphorylated SARM1 plays an important role in the pathological process of rotenone-induced neurodegeneration.

Reinforced antimyeloma therapy via dual-lymphoid activation mediated by a panel of antibodies armed with bridging-BiTE

Immunotherapy using bispecific antibodies including bispecific T-cell engager (BiTE) has the potential to enhance the efficacy of treatment for relapsed/refractory multiple myeloma. However, myeloma may still recur after treatment because of downregulation of a target antigen and/or myeloma cell heterogeneity. To strengthen immunotherapy for myeloma while overcoming its characteristics, we have newly developed a BiTE-based modality, referred to as bridging-BiTE (B-BiTE). B-BiTE was able to bind to both a human immunoglobulin G-Fc domain and the CD3 molecule. Clinically available monoclonal antibodies (mAbs) were bound with B-BiTE before administration, and the mAb/B-BiTE complex induced antitumor T-cell responses successfully while preserving and supporting natural killer cell reactivity, resulting in enhanced antimyeloma effects via dual-lymphoid activation. In contrast, any unwanted off-target immune-cell reactivity mediated by mAb/B-BiTE complexes or B-BiTE itself appeared not to be observed in vitro and in vivo. Importantly, sequential immunotherapy using 2 different mAb/B-BiTE complexes appeared to circumvent myeloma cell antigen escape, and further augmented immune responses to myeloma relative to those induced by mAb/B-BiTE monotherapy or sequential therapy with 2 mAbs in the absence of B-BiTE. Therefore, this modality facilitates easy and prompt generation of a broad panel of bispecific antibodies that can induce deep and durable antitumor responses in the presence of clinically available mAbs, supporting further advancement of reinforced immunotherapy for multiple myeloma and other refractory hematologic malignancies.

STAT1/3 signaling suppresses axon degeneration and neuronal cell death through regulation of NAD+-biosynthetic and consuming enzymes

Nicotinamide adenine dinucleotide (NAD)⁺-biosynthetic and consuming enzymes are involved in various intracellular events through the regulation of NAD⁺ metabolism. Recently, it has become clear that alterations in the expression of NAD⁺-biosynthetic and consuming enzymes contribute to the axonal stability of neurons. We explored soluble bioactive factor(s) that alter the expression of NAD⁺-metabolizing enzymes and found that cytokine interferon (IFN)-γ increased the expression of nicotinamide nucleotide adenylyltransferase 2 (NMNAT2), an NAD⁺-biosynthetic enzyme. IFN-γ activated signal transducers and activators of transcription 1 and 3 (STAT1/3) followed by c-Jun N-terminal kinase (JNK) suppression. As a result, STAT1/3 increased the expression of NMNAT2 at both mRNA and protein levels in a dose- and time-dependent manner and, at the same time, suppressed activation of sterile alpha and Toll/interleukin receptor motif-containing 1 (SARM1), an NAD⁺-consuming enzyme, and increased intracellular NAD⁺ levels. We examined the protective effect of STAT1/3 signaling against vincristine-mediated cell injury as a model of chemotherapy-induced peripheral neuropathy (CIPN), in which axonal degeneration is involved in disease progression. We found that IFN-γ-mediated STAT1/3 activation inhibited vincristine-induced downregulation of NMNAT2 and upregulation of SARM1 phosphorylation, resulting in modest suppression of subsequent neurite degradation and cell death. These results indicate that STAT1/3 signaling induces NMNAT2 expression while simultaneously suppressing SARM1 phosphorylation, and that both these actions contribute to suppression of axonal degeneration and cell death.

CD21lo B Cells Could be a Potential Predictor of Immune-Related Adverse Events in Renal Cell Carcinoma

Immune checkpoint inhibitor (ICI) therapy increases the risk of immune-related adverse events (irAEs). In particular, combination checkpoint blockade (CCB) targeting inhibitory CTLA-4 and PD-1 receptors could lead to irAEs at a higher rate than ICI monotherapy. Management of irAEs is important while using ICIs. However, there are no reliable biomarkers for predicting irAEs. The aim of this study was to elucidate early B cell changes after CCB therapy in patients with renal cell carcinoma (RCC) and verify whether B cells can be a predictor of irAEs. This prospective cohort study was conducted with 23 Japanese patients with metastatic RCC. An increase in the proportion of CD21^lo B cells and CD21^lo memory B cells was confirmed following CCB therapy. Although there were no differences in clinical outcomes between irAE and no-irAE groups, the proportion of CD21^lo B cells at baseline was lower in the irAE group, with a significant increase after the first cycle of CCB therapy. Further analysis revealed a moderate correlation between irAEs and CD21^lo B cell levels at baseline (area under the curve: 0.83, cut-off: 3.13%, sensitivity: 92.3, specificity: 70.0). This finding indicates that patients with low baseline CD21^lo B cell levels warrant closer monitoring for irAEs. The clinical registration number by the Certified Review Board of Ehime University is No. 1902011.

[Recent progress of bispecific antibody-based therapy for hematological malignancies]

Based on the progress of gene-modification technologies, bispecific antibodies that possess antigen-binding sites with two different specificities have been developed. After the success of blinatumomab for treating refractory B-cell leukemia, series of clinical trials using bispecific antibodies for relapsed and refractory hematological malignancies are being conducted. Several bispecific antibodies target an antigen expressed by tumor cells and the CD3 molecule where binding of bispecific antibodies can generate artificial immunological synapses between tumor cells and human T cells. Therefore, fine tuning of binding affinity and/or structural conformation concomitant with bispecific antibodies may be required to induce antitumor effects and regulate immune-related adverse events, such as cytokine release syndrome. In the future, combination therapy of conventional chemotherapy and/or allogeneic stem-cell transplantation with bispecific antibody therapy will be necessary. Furthermore, molecular target therapy with bispecific antibody therapy is expected to pave the way for next-generation target therapy, resulting in the development of a further effective and safe treatment strategy for hematological malignancies.

A single-chain antibody generation system yielding CAR-T cells with superior antitumor function

Cancer immunotherapy using T cells redirected with chimeric antigen receptor (CAR) has shown a lot of promise. We have established a single-chain antibody (scFv) generation system in which scFv library-expressing CAR-T cells can be screened appropriately based on their antitumor functions. A variable region library containing the variable and J regions of the human immunoglobulin light or heavy chain was fused with the variable region of a heavy or light chain encoded by an existing tumor-specific antibody to generate a new scFv library. Then, scFv library-expressing CAR-T cells were generated and stimulated with target cells to concentrate the antigen-specific population. Using this system, target-specific recognition of CAR-T cells appeared to be finely tuned by selecting a new variable region. Importantly, we have demonstrated that the newly optimized scFv-expressing CAR-T cells had better proliferation capacity and durable phenotypes, enabling superior reactivity against advanced tumors in vivo in comparison with the original CAR-T cells. Therefore, the optimization of an scFv is needed to maximize the in vivo antitumor functions of CAR-T cells. This system may allow us to adjust an immunological synapse formed by an scFv expressed by CAR-T cells and a target antigen, representing an ideal form of CAR-T-cell immunotherapy.

[Development of innovative T-cell immunotherapy for hematological malignancies]

With the emergence of cancer immunotherapy, T cells have played important roles in inducing antitumor responses. Many types of antitumor receptors, which possess tumor-binding sites and T-cell activation sites, have been developed. For example, genetically engineered T-cell receptor, chimeric antigen receptor, and bispecific antibody can help us to educate and activate T cells specific for certain tumors. To generate optimal antitumor receptors, (1) selection/distribution of tumor antigens, (2) affinity/specificity and cross-reactivity of antitumor receptors, and (3) T-cell activation signals delivered from antitumor receptors should be considered. Accordingly, we explain how antitumor receptors recognize target antigens and summarize the mechanisms for on-target/off-target reactivity induced by T cells redirected with antitumor receptors. Furthermore, we discuss how antitumor receptors can be optimized for the development of next-generation cancer immunotherapy.

In prenatally diagnosed CPAM, does the affected lobe influence the timing of symptom onset?

PURPOSE

We investigated the relationship between the affected lobe and symptom onset in prenatally diagnosed congenital pulmonary airway malformation (CPAM).

METHODS

53 CPAM patients diagnosed prenatally were reviewed retrospectively by creating 2 groups according to symptom onset. Group Sneo: (symptomatic during the neonatal period; n = 13) and group S > neo: (symptomatic after the neonatal period; n = 40) were compared for type of CPAM, affected lobes, types of symptoms/infections, treatment, duration of follow-up, and histopathology. Requirement for surgery (Sx) was then used to create three subgroups: Sneo + Sx, S > neo + Sx, and Sx-.

RESULTS

Some cases had multiple affected lobes. In Sneo, symptoms developed in 55.6%, 50.0%, 0%, 0%, and 36.8% of right upper lobes (RUL), right middle lobes (RML), right lower lobes (RLL), left upper lobes (LUL), and left lower lobes (LLL) diagnosed with CPAM, prenatally. In S > neo, symptoms developed in 0%, 0%, 6.3%, 55.6%, and 33.3% of RUL, RML, RLL, LUL, and LLL diagnosed with CPAM, prenatally.

CONCLUSION

In prenatally diagnosed CPAM, RUL and RML lesions are more likely to become symptomatic in neonates, and LUL lesions in infants. Surgery is recommended before the onset of respiratory infections after 1 year of age.

Abstract P2-08-31: Predictive and prognostic value of stromal tumor-infiltrating lymphocytes before and after neoadjuvant therapy in triple negative and HER2-positive breast cancer

Background: Lymphocyte predominant breast cancer subgroup, defined as ≥ 50% stromal tumor-infiltrating lymphocytes (sTILs), is associated with high pathological complete response (pCR) rate after neoadjuvant therapy (NAT) and favorable outcome. In a cohort of triple negative (TNBC) and HER2+ breast cancer (BC) patients treated with NAT, we aimed to assess the predictive and prognostic value of pre- and post-NAT sTILs and the information provided by the change in sTILs during NAT.

Materials and methods: Two-hundred and nine consecutive patients (n=80 TNBC; and n=129 HER2+) who received NAT between 2001 and 2009 in our institution were evaluated. Pre-NAT sTILs were assessed on biopsy sample (baseline) and post-NAT sTILs on surgical specimens just for non-pCR patients. sTILs level was categorized as low 0-9%, intermediate 10-49%, and high ≥50%. The change in sTILs during NAT was calculated as the absolute difference between pre- and post-NAT sTILs. We evaluated the association of pre-NAT sTILs and pCR, and the association between pre- and post-NAT sTILs, and their change with relapse-free survival (RFS).

Results: Overall pCR rate was 37.8% (31.3% for TNBC, 41.2% for ER+/HER2+BC, 42.3% for ER-/HER2+BC). In each subtype, pre-NAT low sTILs group was significantly associated with lower pCR rate. During the median follow-up period of 98 months, 44 recurrences (21.1%) were observed. For TNBC, low pre-NAT sTILs group was associated with higher recurrence risk compared with int/high sTILs (HR=4.675 [2.013-10.859], p<0.001). For only non-pCR patients, both pre- and post-NAT sTILs were significantly associated with RFS. The risk of recurrence was higher in the group with low pre-NAT sTILs (HR=5.333 [1.731-16.427], p=0.004), and the group of low post-NAT sTILs (HR=4.271 [1.498-12.173], p=0.007). Patients with the change of sTILs increase during NAT were not associated with RFS, compared with decrease or equal group (log-rank p=0.163). In multivariate analysis including both pre- and post-NAT sTILs, only pre-NAT sTILs retained significance (HR=3.844 [1.190-12.421], p=0.024). Low post-NAT sTILs group showed only a borderline significant association with shorter RFS (HR=2.836 [0.951-8.457], p=0.061), but it suggests that both pre- and post-NAT sTILs might provide independent prognostic information. In ER+/HER2+BC, low pre-NAT sTILs were associated with short RFS (p=0.036), but this association was not significant when only non-pCR patients were considered. In ER−/HER2+BC, sTILs were not significantly associated with RFS.

Conclusion: In TN and HER2+ BCs, tumors with low pre-NAT sTILs have a low likelihood to achieve a pCR (predictive marker). In TNBC, low pre-NAT sTILs were associated with higher recurrence risk. In non-pCR TNBC patients, both low pre- and post-NAT sTILs were associated with shorter RFS. These results suggest that sTILs information should be taken into account when additional post-surgery treatments are considered in non-pCR patients.

Citation Format: Ochi T, Giampaolo B, Murai M, Nozaki F, Kobayashi D, Iwamoto T, Niikura N, Suzuki K, Yamauchi H, Hayashi N. Predictive and prognostic value of stromal tumor-infiltrating lymphocytes before and after neoadjuvant therapy in triple negative and HER2-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-31.

Abstract OT2-02-01: A confirmation study of omitting axillary dissection in patients with breast cancer and positive sentinel nodes

Background

The omission of axillary dissection for positive sentinel-node breast cancer is considered the standard treatment for patients who undergo breast conserving surgery and radiation therapy, according to the results of ACOSOG-Z0011 and AMAROS trials. On the other hand, some surgeons still think that the surgical stress of axillary dissection is minimal, and dissection is permitted. Furthermore, Z0011 contains several problems, such as insufficient number of entry cases and lack of radiation field unity. Thus, we planned a prospective trial to confirm the safety of omitting axillary dissection in patients with breast cancer and positive sentinel nodes.

Trial design

This is a single arm, confirmation study of three medical centers. Prior to surgery, informed consent is obtained, and patients are registered primarily. After surgery, patients with 1 to 2 positive sentinel nodes, for whom axillary dissection was omitted, are finally included in this trial at final registration.

Eligibility criteria

Patients with histologically-diagnosed breast cancer, Tis–2, N0 based on a core needle biopsy, will be included in this trial. Eligible patients must be between 20 and 80 years of age, with a performance status of 0–2 and adequate organ function. They must not have undergone any prior operation, radiation therapy, chemotherapy, endocrine therapy, or immunotherapy.

Specific aims

The primary endpoint is 5-year (y) axillary recurrence rate. Secondary endpoints are 5-y overall survival, 5-y recurrence-free survival, 5-y local recurrence-free survival, the rate of upper-limb lymphedema, quality of life, and comparison of axillary recurrence rates between patients with two or more dissected nodes and those with only one positive node.

Statistical methods

The expected rate of axillary recurrence is 2.0%, and non-inferiority is defined as an axillary recurrence lesser than or equal to 5% in the axillary radiotherapy group. The sample size was calculated with a study power of 80% and type I error of 10% (two-sided). The required number of patients is estimated to be 189.

Present and target accrual

Patient accrual from the three medical centers was initiated in July 2016. We plan to enroll a total of 189 patients at final registration in this trial.

Citation Format: Jibiki N, Hirano A, Ochi T, Sakamoto A, Horiuchi K, Noguchi E, Omi Y, Ogura K, Inoue H, Kamio T, Naritaka Y, Fujibayashi M, Hiroshima K, Nagashima Y, Sakai S, Karasawa K, Okamoto T. A confirmation study of omitting axillary dissection in patients with breast cancer and positive sentinel nodes [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-02-01.

Abstract B031: Development of antimyeloma immunotherapy by exploiting modified antibodies specific for A2/NY-ESO-1

Background: T-cell therapy can be a promising treatment option even in patients with refractory malignancies including myeloma. NY-ESO-1 is a well-known cancer-testis antigen which is expressed by refractory myeloma cells, and a NY-ESO-1_157-165 peptide presented by an HLA-A*02:01 molecule (A2/NY-ESO-1_157) has been demonstrated. Adoptive transfer therapy using T-cells modified with T-cell receptor (TCR) specific for A2/NY-ESO-1_157 successfully induced clinical responses in patients with advanced myeloma. However, TCR-transduced T-cells are laborious to generate and possess the cross-reactivity induced by mispaired and/or introduced TCRs, resulting in increase of unwanted toxicities. T-cell therapy utilizing modified antibodies containing single chain fragment variables (scFvs), such as chimeric antigen receptor (CAR) and bispecific antibody (BiTE) would overcome the issues concerning TCR-T therapy and expand clinical versatility of T-cell therapy targeting NY-ESO-1 in the treatment of refractory myeloma. In this study, we have generated both CAR and BiTE which recognize A2/NY-ESO-1_157, and assessed their anti-myeloma reactivity and cross-reactivity in vitro and in vivo. Methods: Expression of NY-ESO-1 in a panel of myeloma cell lines was examined by real-time PCR and Western blotting. Based on the structure of previously reported monoclonal antibody specific for A2/NY-ESO-1_157 (clone: 3M4E5), we newly synthesized an A2/NY-ESO-1_157-specific scFv. Second generation CAR possessing an scFv linked with CD28 and CD3z was generated. A BiTE composed of an A2/NY-ESO-1_157-specific scFv and a CD3e-binding scFv was also generated. A2/NY-ESO-1_157-specific reactivity mediated by CAR and BiTE-redirected T-cells were assessed by A2/NY-ESO-1_157 tetramer and multiple cytokine assays. Specific lysis of targeT-cells by those T-cells was measured by standard Cr-release assay. Alanine scanning of NY-ESO-1_157 peptide was performed, and nine peptides homologous to NY-ESO-1_157 were synthesized. Cross-reactivity of CAR and BiTE-redirected T-cells for these peptides and NY-ESO-1_157 peptide presented by HLA-A2 alleles was evaluated. NOG mice engrafted with a luciferase-transduced A2+NY-ESO-1+ myeloma cell line (U266/SLR) were treated with CAR-T-cells or T-cells with BiTE, and tumor sizes were measured by bioluminescence imaging assays. Results: Three out of six myeloma cell lines we tested abundantly expressed NY-ESO-1 mRNA and protein. CAR-T-cells established from five out of five donors showed A2/NY-ESO-1_157-specific reactivity. These gene-modified T-cells recognized and killed targeT-cells which naturally process and present A2/NY-ESO-1_157, resulting in anti-myeloma reactivity to A2+NY-ESO-1+ U266 myeloma cells. Newly generated BiTE successfully engaged A2/NY-ESO-1_157 expressing targeT-cells with CD3+ T-cells, thereby peripheral T-cells produced multiple cytokines against A2+NY-ESO-1+ targeT-cells, and lysed them. CAR and BiTE-redirected T-cells can possess cross-reactivity for some of homologous peptides and NY-ESO-1_157 peptide presented by HLA-A2 alleles. Functional avidity of BiTE-redirected T-cells for A2/NY-ESO-1_157 was comparable with that of CAR-T-cells. Importantly, tumor growth was suppressed by intravenous injection of CAR-T-cells and T-cells in combination with BiTE, and their antitumor effects were similarly observed. Conclusions: T-cells redirected with CAR and BiTE both successfully showed anti-myeloma reactivity in an A2/NY-ESO-1_157-specific manner. An A2/NY-ESO-1_157-specific BiTE displayed a potential to induce sufficient antitumor T-cell responses against myeloma cells in vivo. These two scFv-based modalities also require to pay attention to unwanted cross-reactivity; however, they can provide efficacious and flexible options for the treatment of HLA-A2-positive patients with refractory myeloma.

Citation Format: Toshiki Ochi, Masaki Maruta, Kazushi Tanimoto, Hiroaki Asai, Takashi Saitou, Yoshihiro Yakushijin, Hiroshi Fujiwara, Takeshi Imamura, Katsuto Takenaka, Masaki Yasukawa. Development of antimyeloma immunotherapy by exploiting modified antibodies specific for A2/NY-ESO-1 [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B031.

Mechanisms underlying the lack of endogenous processing and CLIP-mediated binding of the invariant chain by HLA-DP84Gly

While the principles of classical antigen presentation via MHC class II are well-established, the mechanisms for the many routes of cross-presentation by which endogenous antigens become associated with class II molecules are not fully understood. We have recently demonstrated that the single amino acid polymorphism HLA-DPβ^84Gly (DP^84Gly) is critical to abrogate class II invariant chain associated peptide (CLIP) region-mediated binding of invariant chain (Ii) to DP, allowing endoplasmic reticulum (ER)-resident endogenous antigens to constitutively associate with DP^84Gly such as DP4. In this study, we demonstrate that both the CLIP and N-terminal non-CLIP Ii regions cooperatively generate an Ii conformation that cannot associate with DP^84Gly via the CLIP region. We also demonstrate the ability of DP4 to efficiently process and present antigens encoded in place of CLIP in a chimeric Ii, regardless of wild type Ii and HLA-DM expression. These data highlight the complex interplay between DP polymorphisms and the multiple Ii regions that cooperatively regulate this association, ultimately controlling the presentation of endogenous antigens on DP molecules. These results may also offer a mechanistic explanation for recent studies identifying the differential effects between DP^84Gly and DP^84Asp as clinically relevant in human disease.

HLA-DP84Gly constitutively presents endogenous peptides generated by the class I antigen processing pathway

Classical antigen processing leads to the presentation of antigenic peptides derived from endogenous and exogenous sources for MHC class I and class II molecules, respectively. Here we show that, unlike other class II molecules, prevalent HLA-DP molecules with β-chains encoding Gly84 (DP^84Gly) constitutively present endogenous peptides. DP^84Gly does not bind invariant chain (Ii) via the class II-associated invariant chain peptide (CLIP) region, nor does it present CLIP. However, Ii does facilitate the transport of DP^84Gly from the endoplasmic reticulum (ER) to the endosomal/lysosomal pathway by transiently binding DP^84Gly via a non-CLIP region(s) in a pH-sensitive manner. Accordingly, like class I, DP^84Gly constitutively presents endogenous peptides processed by the proteasome and transported to the ER by the transporter associated with antigen processing (TAP). Therefore, DP^84Gly, found only in common chimpanzees and humans, uniquely uses both class I and II antigen-processing pathways to present peptides derived from intracellular and extracellular sources.

Identification of Functional and Expression Polymorphisms Associated With Risk for Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis

Objective

To identify risk alleles relevant to the causal and biologic mechanisms of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV).

Methods

A genome‐wide association study and subsequent replication study were conducted in a total cohort of 1,986 cases of AAV (patients with granulomatosis with polyangiitis [Wegener's] [GPA] or microscopic polyangiitis [MPA]) and 4,723 healthy controls. Meta‐analysis of these data sets and functional annotation of identified risk loci were performed, and candidate disease variants with unknown functional effects were investigated for their impact on gene expression and/or protein function.

Results

Among the genome‐wide significant associations identified, the largest effect on risk of AAV came from the single‐nucleotide polymorphism variants rs141530233 and rs1042169 at the HLA–DPB1 locus (odds ratio [OR] 2.99 and OR 2.82, respectively) which, together with a third variant, rs386699872, constitute a triallelic risk haplotype associated with reduced expression of the HLA–DPB1 gene and HLA–DP protein in B cells and monocytes and with increased frequency of complementary proteinase 3 (PR3)–reactive T cells relative to that in carriers of the protective haplotype. Significant associations were also observed at the SERPINA1 and PTPN22 loci, the peak signals arising from functionally relevant missense variants, and at PRTN3, in which the top‐scoring variant correlated with increased PRTN3 expression in neutrophils. Effects of individual loci on AAV risk differed between patients with GPA and those with MPA or between patients with PR3‐ANCAs and those with myeloperoxidase‐ANCAs, but the collective population attributable fraction for these variants was substantive, at 77%.

Conclusion

This study reveals the association of susceptibility to GPA and MPA with functional gene variants that explain much of the genetic etiology of AAV, could influence and possibly be predictors of the clinical presentation, and appear to alter immune cell proteins and responses likely to be key factors in the pathogenesis of AAV.

Transient stimulation expands superior antitumor T cells for adoptive therapy

Adoptive cell therapy is a potentially curative therapeutic approach for patients with cancer. In this treatment modality, antitumor T cells are exponentially expanded in vitro prior to infusion. Importantly, the results of recent clinical trials suggest that the quality of expanded T cells critically affects their therapeutic efficacy. Although anti-CD3 mAb-based stimulation is widely used to expand T cells in vitro, a protocol to generate T cell grafts for optimal adoptive therapy has yet to be established. In this study, we investigated the differences between T cell stimulation mediated by anti-CD3/CD28 mAb-coated beads and cell-based artificial antigen-presenting cells (aAPCs) expressing CD3/CD28 counter-receptors. We found that transient stimulation with cell-based aAPCs, but not prolonged stimulation with beads, resulted in the superior expansion of CD8⁺ T cells. Transiently stimulated CD8⁺ T cells maintained a stem cell-like memory phenotype and were capable of secreting multiple cytokines significantly more efficiently than chronically stimulated T cells. Importantly, the chimeric antigen receptor-engineered antitumor CD8⁺ T cells expanded via transient stimulation demonstrated superior persistence and antitumor responses in adoptive immunotherapy mouse models. These results suggest that restrained stimulation is critical for generating T cell grafts for optimal adoptive immunotherapy for cancer.

Generating De Novo Antigen-specific Human T Cell Receptors by Retroviral Transduction of Centric Hemichain

T cell receptors (TCRs) are used clinically to direct the specificity of T cells to target tumors as a promising modality of immunotherapy. Therefore, cloning TCRs specific for various tumor-associated antigens has been the goal of many studies. To elicit an effective T cell response, the TCR must recognize the target antigen with optimal affinity. However, cloning such TCRs has been a challenge and many available TCRs possess sub-optimal affinity for the cognate antigen. In this protocol, we describe a method of cloning de novo high affinity antigen-specific TCRs using existing TCRs by exploiting hemichain centricity. It is known that for some TCRs, each TCRα or TCRβ hemichain do not contribute equally to antigen recognition, and the dominant hemichain is referred to as the centric hemichain. We have shown that by pairing the centric hemichain with counter-chains differing from the original counter-chain, we are able to maintain the antigen specificity, while modulating its interaction strength for the cognate antigen. Thus, the therapeutic potential of a given TCR can be improved by optimizing the pairing between the centric and counter hemichains.

Novel immunotherapy for adult T-cell leukemia/lymphoma: Targeting aurora kinase A

Adult T-cell leukemia/lymphoma is caused by infection with HTLV-1, following a long latent period. Immunotherapy targeting Aurora kinase A, a tumor-associated antigen over-expressed in adult T-cell leukemia/lymphoma, holds great therapeutic potential. We review the evidence in favor of a therapeutic strategy combining vaccination and TCR-gene transfer against this target.

BET bromodomain inhibition enhances T cell persistence and function in adoptive immunotherapy models

Adoptive immunotherapy is a potentially curative therapeutic approach for patients with advanced cancer. However, the in vitro expansion of antitumor T cells prior to infusion inevitably incurs differentiation towards effector T cells and impairs persistence following adoptive transfer. Epigenetic profiles regulate gene expression of key transcription factors over the course of immune cell differentiation, proliferation, and function. Using comprehensive screening of chemical probes with defined epigenetic targets, we found that JQ1, an inhibitor of bromodomain and extra-terminal motif (BET) proteins, maintained CD8+ T cells with functional properties of stem cell-like and central memory T cells. Mechanistically, the BET protein BRD4 directly regulated expression of the transcription factor BATF in CD8+ T cells, which was associated with differentiation of T cells into an effector memory phenotype. JQ1-treated T cells showed enhanced persistence and antitumor effects in murine T cell receptor and chimeric antigen receptor gene therapy models. Furthermore, we found that histone acetyltransferase p300 supported the recruitment of BRD4 to the BATF promoter region, and p300 inhibition similarly augmented antitumor effects of the adoptively transferred T cells. These results demonstrate that targeting the BRD4-p300 signaling cascade supports the generation of superior antitumor T cell grafts for adoptive immunotherapy.

Mouse and Human CD1d-Self-Lipid Complexes Are Recognized Differently by Murine Invariant Natural Killer T Cell Receptors

Invariant natural killer T (iNKT) cells recognize self-lipids presented by CD1d through characteristic TCRs, which mainly consist of the invariant Vα14-Jα18 TCRα chain and Vβ8.2, 7 or 2 TCRβ chains with hypervariable CDR3β sequences in mice. The iNKT cell-CD1d axis is conserved between humans and mice, and human CD1d reactivity of murine iNKT cells have been described. However, the detailed differences between the recognition of human and mouse CD1d bound to various self-lipids by mouse iNKT TCRs are largely unknown. In this study, we generated a de novo murine iNKT TCR repertoire with a wider range of autoreactivity compared with that of naturally occurring peripheral iNKT TCRs. Vβ8.2 mouse iNKT TCRs capable of recognizing the human CD1d-self-lipid tetramer were identified, although such clones were not detectable in the Vβ7 or Vβ2 iNKT TCR repertoire. In line with previously reports, clonotypic Vβ8.2 iNKT TCRs with unique CDR3β loops did not discriminate among lipids presented by mouse CD1d. Unexpectedly, however, these iNKT TCRs showed greater ligand selectivity toward human CD1d presenting the same lipids. Our findings demonstrated that the recognition of mouse and human CD1d-self-lipid complexes by murine iNKT TCRs is not conserved, thereby further elucidating the differences between cognate and cross-species reactivity of self-antigens by mouse iNKT TCRs.

CD4(+) and CD8(+) TCRβ repertoires possess different potentials to generate extraordinarily high-avidity T cells

Recent high throughput sequencing analysis has revealed that the TCRβ repertoire is largely different between CD8(+) and CD4(+) T cells. Here, we show that the transduction of SIG35α, the public chain-centric HLA-A*02:01(A2)/MART127-35 TCRα hemichain, conferred A2/MART127-35 reactivity to a substantial subset of both CD8(+) and CD4(+) T cells regardless of their HLA-A2 positivity. T cells individually reconstituted with SIG35α and different A2/MART127-35 TCRβ genes isolated from CD4(+) or CD8(+) T cells exhibited a wide range of avidity. Surprisingly, approximately half of the A2/MART127-35 TCRs derived from CD4(+) T cells, but none from CD8(+) T cells, were stained by A2/MART127-35 monomer and possessed broader cross-reactivity. Our results suggest that the differences in the primary structure of peripheral CD4(+) and CD8(+) TCRβ repertoire indeed result in the differences in their ability to form extraordinarily high avidity T cells which would otherwise have been deleted by central tolerance.

Antileukemia multifunctionality of CD4(+) T cells genetically engineered by HLA class I-restricted and WT1-specific T-cell receptor gene transfer

To develop gene-modified T-cell-based antileukemia adoptive immunotherapy, concomitant administration of CD4(+) and CD8(+) T cells that have been gene modified using identical HLA class I-restricted leukemia antigen-specific T-cell receptor (TCR) gene transfer has not yet been fully investigated. Here, using CD4(+) and CD8(+) T cells that had been gene modified with a retroviral vector expressing HLA-A*24:02-restricted and Wilms' tumor 1 (WT1)-specific TCR-α/β genes and siRNAs for endogenous TCRs (WT1-siTCR/CD4(+) T cells and WT1-siTCR/CD8(+) T cells), we examined the utility of this strategy. WT1-siTCR/CD4(+) T cells sufficiently recognized leukemia cells in an HLA class I-restricted manner and provided target-specific Th1 help for WT1-siTCR/CD8(+) T cells. By using a xenografted mouse model, we found that WT1-siTCR/CD4(+) T cells migrated to leukemia sites and subsequently attracted WT1-siTCR/CD8(+) T cells via chemotaxis. Therapy-oriented experiments revealed effective enhancement of leukemia suppression mediated by concomitant administration of WT1-siTCR/CD4(+) T cells and WT1-siTCR/CD8(+) T cells. Importantly, this augmented efficacy in the presence of WT1-siTCR/CD4(+) T cells was correlated with longer survival and enhanced formation of memory T cells by WT1-siTCR/CD8(+) T cells. Collectively, our experimental findings strongly suggest that this strategy would be clinically advantageous for the treatment of human leukemia.

Optimization of T-cell Reactivity by Exploiting TCR Chain Centricity for the Purpose of Safe and Effective Antitumor TCR Gene Therapy

Adoptive transfer of T cells redirected by a high-affinity antitumor T-cell receptor (TCR) is a promising treatment modality for cancer patients. Safety and efficacy depend on the selection of a TCR that induces minimal toxicity and elicits sufficient antitumor reactivity. Many, if not all, TCRs possess cross-reactivity to unrelated MHC molecules in addition to reactivity to target self-MHC/peptide complexes. Some TCRs display chain centricity, in which recognition of MHC/peptide complexes is dominated by one of the TCR hemi-chains. In this study, we comprehensively studied how TCR chain centricity affects reactivity to target self-MHC/peptide complexes and alloreactivity using the TCR, clone TAK1, which is specific for human leukocyte antigen-A*24:02/Wilms tumor 1(235-243) (A24/WT1(235)) and cross-reactive with B*57:01 (B57). The TAK1β, but not the TAK1α, hemi-chain possessed chain centricity. When paired with multiple clonotypic TCRα counter-chains encoding TRAV12-2, 20, 36, or 38-2, the de novo TAK1β-containing TCRs showed enhanced, weakened, or absent reactivity to A24/WT1(235) and/or to B57. T cells reconstituted with these TCRα genes along with TAK1β possessed a very broad range (>3 log orders) of functional and structural avidities. These results suggest that TCR chain centricity can be exploited to enhance desired antitumor TCR reactivity and eliminate unwanted TCR cross-reactivity. TCR reactivity to target MHC/peptide complexes and cross-reactivity to unrelated MHC molecules are not inextricably linked and are separable at the TCR sequence level. However, it is still mandatory to carefully monitor for possible harmful toxicities caused by adoptive transfer of T cells redirected by thymically unselected TCRs.

Specific roles of each TCR hemichain in generating functional chain-centric TCR

TCRα- and β-chains cooperatively recognize peptide-MHC complexes. It has been shown that a "chain-centric" TCR hemichain can, by itself, dictate MHC-restricted Ag specificity without requiring major contributions from the paired TCR counterchain. Little is known, however, regarding the relative contributions and roles of chain-centric and its counter, non-chain-centric, hemichains in determining T cell avidity. We comprehensively analyzed a thymically unselected T cell repertoire generated by transducing the α-chain-centric HLA-A*02:01(A2)/MART127-35 TCRα, clone SIG35α, into A2-matched and unmatched postthymic T cells. Regardless of their HLA-A2 positivity, a substantial subset of peripheral T cells transduced with SIG35α gained reactivity for A2/MART127-35. Although the generated A2/MART127-35-specific T cells used various TRBV genes, TRBV27 predominated with >10(2) highly diverse and unique clonotypic CDR3β sequences. T cells individually reconstituted with various A2/MART127-35 TRBV27 TCRβ genes along with SIG35α possessed a wide range (>2 log orders) of avidity. Approximately half possessed avidity higher than T cells expressing clone DMF5, a naturally occurring A2/MART127-35 TCR with one of the highest affinities. Importantly, similar findings were recapitulated with other self-Ags. Our results indicate that, although a chain-centric TCR hemichain determines Ag specificity, the paired counterchain can regulate avidity over a broad range (>2 log orders) without compromising Ag specificity. TCR chain centricity can be exploited to generate a thymically unselected Ag-specific T cell repertoire, which can be used to isolate high-avidity antitumor T cells and their uniquely encoded TCRs rarely found in the periphery because of tolerance.

Time course of axial and radial diffusion kurtosis of white matter infarctions: period of pseudonormalization

BACKGROUND AND PURPOSE

Diffusion kurtosis is a statistical measure for quantifying the deviation of the water diffusion profile from a Gaussian distribution. The current study evaluated the time course of diffusion kurtosis in patients with cerebral infarctions, including perforator, white matter, cortical, and watershed infarctions.

MATERIALS AND METHODS

Subjects were 31 patients, representing 52 observations of lesions. The duration between the onset and imaging ranged from 3 hours to 122 days. Lesions were categorized into 4 groups listed above. Diffusion kurtosis images were acquired with b-values of 0, 1000, and 2000 s/mm(2) applied in 30 directions; variables including DWI signal, ADC, fractional anisotropy, radial diffusivity, axial diffusivity, radial kurtosis, and axial kurtosis, were obtained. The time courses of the relative values (lesion versus contralateral) for these variables were evaluated, and the pseudonormalization period was calculated.

RESULTS

Diffusion kurtosis was highest immediately after the onset of infarction. Trend curves showed that kurtosis decreased with time after onset. Pseudonormalization for radial/axial kurtosis occurred at 13.2/59.9 days for perforator infarctions, 33.1/40.6 days for white matter infarctions, 34.8/35.9 days for cortical infarctions, and 34.1/28.2 days after watershed infarctions. For perforator infarctions, pseudonormalization occurred in the following order: radial kurtosis, ADC, axial kurtosis, and DWI.

CONCLUSIONS

Diffusion kurtosis variables in lesions increased early after infarction and decreased with time. Information provided by diffusion kurtosis imaging, including axial and radial kurtosis, seems helpful in conducting a detailed evaluation of the age of infarction, in combination with T2WI, DWI, and ADC.

Adoptive transfer of genetically engineered WT1-specific cytotoxic T lymphocytes does not induce renal injury

Because WT1 is expressed in leukemia cells, the development of cancer immunotherapy targeting WT1 has been an attractive translational research topic. However, concern of this therapy still remains, since WT1 is abundantly expressed in renal glomerular podocytes. In the present study, we clearly showed that WT1-specific cytotoxic T lymphocytes (CTLs) certainly exerted cytotoxicity against podocytes in vitro; however, they did not damage podocytes in vivo. This might be due to the anatomical localization of podocytes, being structurally separated from circulating CTLs in glomerular capillaries by an exceptionally thick basement membrane.

Hepatocyte destruction with enhanced collagen synthesis: characteristic feature of chronic hepatitis C patients on haemodialysis

Hepatitis C virus (HCV) infection is frequent among patients with end-stage renal disease on haemodialysis and is considered to be an independent risk factor for mortality in this setting. However, only a few of these patients are treated with anti-hepatitis virus treatment before the development of end-stage renal disease. Recent guidelines recommend identification of patients with good prognoses who are in need of interferon treatment, but we know little of patients who must be treated urgently. Ninety-eight patients on haemodialysis (48 anti-HCV-positive and 50 anti-HCV-negative patients) were enrolled in this study; HCV RNA was detected in 43 anti-HCV-positive patients. Univariate analysis and multivariate regression analysis were applied to identify variables independently associated with persistent HCV infection. Seven variables were proven to be associated with persistent HCV infection. Among them, type IV collagen 7S and N-terminal propeptide of type III procollagen (P-III-P) were defined as independent variables useful in distinguishing HCV RNA-positive patients from HCV RNA-negative patients with 0.91 sensitivity, 0.91 specificity, 0.89 positive predictive value and 0.93 negative predictive value. Our observations suggest that hepatocyte destruction with enhanced liver fibrosis is a characteristic clinical feature of persistent HCV infection. Type IV collagen 7S of ≥ 5 ng/mL and/or P-III-P of ≥ 5 U/mL would be useful markers to identify patients in need of interferon treatment, which supports the idea of the Kidney Disease: Improving Global Outcomes guidelines that a good prognosis in patients with HCV infection on haemodialysis should prompt consideration for IFN treatment when applicable.

Gemcitabine enhances Wilms' tumor gene WT1 expression and sensitizes human pancreatic cancer cells with WT1-specific T-cell-mediated antitumor immune response

Wilms' tumor gene (WT1), which is expressed in human pancreatic cancer (PC), is a unique tumor antigen recognized by T-cell-mediated antitumor immune response. Gemcitabine (GEM), a standard therapeutic drug for PC, was examined for the regulation of WT1 expression and the sensitizing effect on PC cells with WT1-specific antitumor immune response. Expression of WT1 was examined by quantitative PCR, immunoblot analysis, and confocal microscopy. Antigenic peptide of WT1 presented on HLA class I molecules was detected by mass spectrometry. WT1-specific T-cell receptor gene-transduced human T cells were used as effecter T cells for the analysis of cytotoxic activity. GEM treatment of human MIAPaCa2 PC cells enhanced WT1 mRNA levels, and this increase is associated with nuclear factor kappa B activation. Tumor tissue from GEM-treated MIAPaCa2-bearing SCID mice also showed an increase in WT1 mRNA. Some human PC cell lines other than MIAPaCa2 showed up-regulation of WT1 mRNA levels following GEM treatment. GEM treatment shifted WT1 protein from the nucleus to the cytoplasm, which may promote proteasomal processing of WT1 protein and generation of antigenic peptide. In fact, presentation of HLA-A*2402-restricted antigenic peptide of WT1 (CMTWNQMNL) increased in GEM-treated MIAPaCa2 cells relative to untreated cells. WT1-specific cytotoxic T cells killed MIAPaCa2 cells treated with an optimal dose of GEM more efficiently than untreated MIAPaCa2 cells. GEM enhanced WT1 expression in human PC cells and sensitized PC cells with WT1-specific T-cell-mediated antitumor immune response.

Surgical treatment for skeletal metastases from soft tissue sarcomas: experience with 23 lesions in 20 patients

Purpose. This paper reports the procedures and the clinical results of a series of surgical treatments for skeletal metastases from soft tissue sarcomas.Subjects and methods. Surgical treatment of metastatic bony lesions from soft tissue sarcomas has been carried out over a 20 year period (1975-1996). Thirty-two patients developed skeletal metastases from soft tissue sarcomas, and 20 of these cases received surgical treatment. The 23 metastatic bony lesions in these 20 patients were treated using the following surgical approaches: wide resection with prosthetic replacement in five lesions, wide or marginal resection without reconstruction in four lesions, intramedullarly nailing with curettage and methylmethacrylate cementation in four lesions, marginal resection of vertebral body with replacement by a ceramic prosthesis in three lesions, laminectomy in three lesions, intramedullarly nailing in two lesions, and curettage in two lesions.Results. Relief of pain was achieved in 17 of the 20 patients. The ambulatory status of the patients with metastasis in the lower extremity or periacetabular region was significantly improved in nine of 10 cases. Seventeen patients died of disease, with a mean survival period of 17.9 months after surgery for metastasis.Discussion. Although surgical treatment for skeletal metastases from soft tissue sarcomas cannot save the life of the patient, it can be of value in improving their well-being and overall quality of life. In these cases, surgical intervention may be more frequently indicated than in tumors with an osteoblastic or mixed pattern.

Transient hyperintensity in the subthalamic nucleus and globus pallidus of newborns on T1-weighted images

BACKGROUND AND PURPOSE

In the brains of newborns, changes in signal intensity in most structures can be explained by the development of myelination. However, there are some structures for which signal intensity changes cannot be accounted for by myelination alone. We examined the STN and globus pallidus signal intensities and tried to determine whether a relationship exists between the signal intensity and the postnatal age or the gestational age at the examination.

MATERIALS AND METHODS

We examined T1WI and T2WI obtained from 79 neonates who showed normal development at their 2-year follow-up examinations. We performed both qualitative and quantitative (signal intensity ratio to the thalamus) evaluation of the STN and globus pallidus signals, and we examined the correlation between signal intensity changes and the age of neonates.

RESULTS

With increasing postnatal age at examination, the high signal intensity on the T1WI for both STN and globus pallidus diminished. Although the disappearance of this hyperintensity was well correlated with the postnatal age at examination for both the qualitative and quantitative studies, there was no correlation with gestational age at examination. For the T2WI, there was no correlation with either the postnatal age or the gestational age at examination.

CONCLUSIONS

Signal intensity on T1WI in the STN and globus pallidus is not related to the gestational age at examination; instead, signal intensities on T1WI seem to be more dependent upon the postnatal age at examination.

Requisite considerations for successful adoptive immunotherapy with engineered T-lymphocytes using tumor antigen-specific T-cell receptor gene transfer

INTRODUCTION

Although engineered T-cell-based antitumor immunotherapy using tumor-antigen-specific T-cell receptor (TCR) gene transfer is undoubtedly a promising strategy, a number of studies have revealed that it has several drawbacks.

AREAS COVERED

This review covers selected articles detailing recent progress in this field, not only for solid tumors, but also for leukemias. In terms of achieving uniform therapeutic quality of TCR gene-modified T cells as an 'off-the-shelf' product, the authors abstract and discuss the requisite conditions for successful outcome, including: i) the optimal target choice reflecting the specificity of the introduced TCR, ii) the quality and quantity of expressed TCRs in gene-modified T cells, and additional genetic modification reflecting enhanced antitumor functionality, and iii) 'on-' and 'off-target' adverse events caused by the quality of the introduced TCRs and other adverse events related to genetic modification itself. Readers will be able to readily abstract recent advances in TCR gene-transferred T-cell therapy, centering notably on efforts to obtain uniformity in the therapeutic functionality of engineered T cells.

EXPERT OPINION

Harmonizing the functionality and target specificity of TCR will allow the establishment of clinically useful adoptive immunotherapy in the near future.